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http://www.mf.unze.ba/index.php?option=com_content&view=article&id=118&Itemid=107

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ISSN 1512-5173 http://www.mf.unze.ba/index.php?option=com_content&view=article&id=118&Itemid=107

MAŠINSTVO ČASOPIS ZA MAŠINSKO INŽENJERSTVO

JOURNAL OF MECHANICAL ENGINEERING Godina (Volume) 13, Broj (Number) 1, Zenica, Januar – Mart (January – March) 2016.

Uredništvo (Editorial): Fakultetska 1, 72000 Zenica Bosnia and Herzegovina Tel: +387 32 449 143; 449 145 Fax: +387 32 246 612 e-mail: [email protected] [email protected] [email protected]

Osnivač i izvršni izdavač (Founders and Executive Publisher): University of Zenica Faculty of Mechanical Engineering Fakultetska 1, 72000 Zenica Bosnia and Herzegovina Recenzioni odbor (Review committe): Dr. Aleksandar Karač, Dr. Izet Smajević, Dr. Nevzet Merdić, Dr. Jusuf Duraković, Dr. Safet Brdarević, Dr. Sabahudin Jašarević

Glavni i odgovorni urednik (Editor and Chief): Prof. Dr. Sc. Safet Brdarević

Časopis izlazi tromjesečno (Journal tree monthly Urednički odbor (Editorial Board): Dr. Safet Brdarević (B&H), Dr. Jože Duhovnik (Slovenia), Dr. Vidosav Majstorović (Serbia), Dr. Milan Jurković (Croatia), Dr. Sabahudin Ekinović (B&H), Dr. Gheorge I. Gheorge (Romania), Dr. Alojz Ivanković (Ireland), Dr. Joan Vivancos (Spain), Dr. Ivo Čala (Croatia), Dr. Slavko Arsovski (Serbia), Dr. Albert Weckenman (Germany), Dr. Ibrahim Pašić (France), Dr. Zdravko Krivokapić (Montenegro), Dr. Rainer Lotzien (Germany)

Tehnički urednik (Technical Editor): Prof. Dr. Sabahudin Jašarević Štampa (Print): Štamparija Fojnica d.o.o., Fojnica Uređenje zaključeno (Preparation ended): 31.03.2016.

Časopis je evidentiran u evidenciji javnih glasila pri Ministarstvu nauke, obrazovanja, kulture i sport Federacije Bosne i Hercegovine pod brojem 651. Časopis u pretežnom iznosu finansira osnivač i izdavač. Časopis MAŠINSTVO u pravilu izlazi u četiri broja godišnje. Rukopisi se ne vraćaju

The Journal is listed under No 651 in the list of public journals in the Ministry of science, education, culture and sport of the Federation of Bosnia and Herzegovina. The Journals is mostly financed by founder and publisher. Frequency of Journal MAŠINSTVO is 4 issues a year. Manuscripts are not returned

Časopis objavljuje naučne i stručne radove i informacije od interesa za stručnu i privrednu javnost iz oblasti mašinstva i srodnih grana vezanih za područje primjene i izučavanja mašinstva. Posebno se obrađuju slijedeće tematike: - tehnologija prerade metala, plastike i gume, - projektovanje i konstruisanje mašina i postrojenja, - projektovanje proizvodnih sistema, - energija, - održavanje sredstava za rad, - kvalitet, efikasnost sistema i upravljanje proizvodnim i poslovnim sistemima, - informacije o novim knjigama, - informacije o naučnim skupovima - informacije sa Univerziteta,

The journal publishes scientific and professional papers and information of interest to professional and economic releases in mechanical engineering and related fields. In particular, the following topics are treated: - Technology for processing metal, plastic and rubber, - Design and construction of machines and plants, - The design of production systems, - Energy, - Maintenance funds for the work, - Quality and efficiency of the system and the management of production and business systems, - Information about new books, - Information about scientific meetings - Information from the University,

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RIJEČ UREDNIKA Poštovane kolegice i kolege U prvom broju druge godine nastavka izlaženja časopisa predstavljamo Vam pet različitih radova iz šire oblasti mašinstva i grane vezanih za mašinstvo. Radovi su nastali u postupku posebnih istraživanja za rješavanje problema iz privrede. Tu si i obavijesti- pozivi za dva naučno-stručna skupa u organizaciji Univerziteta u Zenici (Mašinski fakultet):

- IV konferencija ODRŽAVANJE (2016), Zenica, 02-04 juna 2016. i

- 19th Intrenational Scientific/Expert Conference " Trends in the Development of Machinery nad Associated technology" septembar 2016.

- Nastavljamo predstavljanje laboratorijskih kapaciteta u Bosni i Hercegovini. U ovom broju je to laboratorija za hemijska istraživanja Fakulteta za metalurgiju i materijale Univerziteta u Zenici. Takođe smo prikazali osnovne tehničko-komercijalne informacije o uspješnoj firmi ITC. Očekujemo da će Vam predstavljeni sadržaj bit od koristi kao i Vaš doprinos navedenih brojeva časopisa.

Vaš glavni i odgovorni urednikProf. emeritus dr. Safet Brdarević

EDITORIAL Dear Colleagues In the first issue of the second year continuation of the journal present you five different papers in the wider field of mechanical engineering and related branches of engineering. The papers were created in the special research for solving problems in the economy. There are also Inform calls for two scientific conference organized by the University of Zenica (Mechanical Engineering): - MAINTENANCE IV Conference (2016), Zenica, 02-04 June 2016, - 19th Intrenational Scientific/Expert Conference "Trends in the Development of Machinery of Associated Technology" September 2016. We continue the presentation of laboratory capacity in Bosnia and Herzegovina. In this issue has to laboratory for chemical analysis Faculty of Metallurgy and Materials Science, University of Zenica. We also show the basic technical and commercial information on successful companies ITC. We expect that you will present the content of benefits as well as your contribution to the above issues of the journal.

Your editor in chiefProf. emeritus dr. Safet Brdarević

SADRŽAJ

1. Testing of new Type of Split Sleeve for Pipeline Repairs by Internal Pressure M. Patek, A. Sládek, M. Mičian 3

2. Rekonstrukcija kanala za odvođenje dimnih plinova u Termoelektrani “Kakanj” E. Ekinović, N. Hodžić, A. Kahriman 9

3. Projektovanje sastava samozbijajućeg betona sa visokim udjelom kalcijskog elektro-filterskog pepela za prefabrikovane elemente A. Mujkanović, I.Bušatlić, M. Jovanović, Dž. Bečirhodžić, V. Redžić 23

4. Primjenjivost tehnika za izradu vremenskih planova održavanja tehničkih sustava D. Vidaković, Z. Kraus, H. Glavaš 41

5. Energetski potencijal i postupci termičke obrade otpadnih auto guma J. Sredojević, M. Krajšnik 57

Uputstvo za autore ............................... ......69

CONTENTS

1. Testing of new Type of Split Sleeve for Pipeline Repairs by Internal Pressure M. Patek, A. Sládek, M. Mičian 3

2. Reconstruction of Channels for Flue Gases Discharge in Thermal Power Plant „Kakanj“ E. Ekinović, N. Hodžić, A. Kahriman 9

3. Mix Design of Self-Compacting Concrete Containing High Volume Calcareous Fly Ash for Precast Elements A. Mujkanović, I.Bušatlić, M. Jovanović, Dž. Bečirhodžić, V. Redžić 23

4. The Applicability Technique for Making Time Plans for Maintenance of Tehnical Systems N D. Vidaković, Z. Kraus, H. Glavaš 41

5. Energy Potential and Thermal Treatment of Waste Tyres J. Sredojević, M. Krajšnik 57

Instruction for authors .......... .....................69

Mašinstvo 1(13), 3 – 8, (2016) M. Patek, ….: TESTING OF NEW TYPE OF SPLIT...

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TESTING OF NEW TYPE OF SPLIT SLEEVE FOR PIPELINE REPAIRS BY INTERNAL PRESSURE

Marek Patek, Augustín Sládek, Miloš Mičian University of Žilina, Faculty of Mechanical Engineering, Department of Technological Engineering, Univerzitná 8215/1, 010 26 Žilina, Slovak Republic Keywords: Branch connection, Defects repair, Split sleeve, Pressure test Paper received: 22.10.2015. Paper accepted: 08.03.2016.

Conference paper SUMMARY Repairing technologies for pipelines still require attention due to large extent of distribution network containing different construction parts including elbows, branch connections and others. Repairing of the defects in the branch connection area without interruption of the gas supply is very difficult. Such defects mostly require replacing of the damaged part with interruption of media supply or construction of the bypass around the branch connection. The first method is sometimes difficult to realize and the second is relatively expensive due of necessity of hot-tapping (creating of the hole into the pipeline and welding without the interruption of media supply). In this article, new repairing technology with application of special split sleeve is presented. Computation of required wall thickness is described together with testing based on internal pressure.

1. INTRODUCTION The various types of integrity break can be discovered on pipelines during the service time of high-pressure gas distribution network. Statistically, the most common cause of pipeline failure until the 2013 was external interference (28 %), followed by corrosion (26 %), construction defects/material failure (16 %), ground movement (16 %), hot-tap made by error (6 %) and the rest were other and unknown causes (8 %) [1]. Very dangerous are defects that have sharp geometrical shape and which act like local stress concentrators [2]. Numerous kinds of repair techniques of the gas pipelines are now available including the cut out and replacement of the pipeline, construction of the bypass along the damaged area, grinding, weld deposition, metallic or composite sleeves, etc. [3]. Although the repairing techniques for straight parts of pipelines are quite well established, only a few of them are applicable for branch connections defects (for ex. defects in the area of fillet weld between header and branch pipe (Fig. 1)). Defects of the branch connections can be mostly repaired only by the replacing of damaged area of the pipeline, which requires interruption of media supply or bypass

construction. Both technologies are expensive and there is still a necessity of designing new (or improved) repairing technologies. Some of the possible technology of repairs is application of the split sleeves that may be in some cases and with appropriate construction used to various defects, even with gas (or another media) leakage.

Figure 1. Split sleeve for branch connection

repairs Recently a new type of split sleeve for such defects repairs has been designed [4,5]. Split sleeve (Fig. 2) consist of the cylinder part and


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sphere-like part (split into two segments), which has to ensure safely installation of the sleeve to the repaired branch connection. Parts of the prepared split sleeve are during the repairing process placed to the area with defect and welded together by butt welds (Fig. 3). To the header and branch pipe is sleeve welded by full encirclement fillet welds after the completion of the butt welds. Whereas internal space of sleeve

will be exposed to leaking gas during the assembling process, it is necessary to ensure sealing up of the internal space and places of welding. Sealing up of the internal space of split sleeve is designed with using sealants fixed to so-called “sealant carriers”. Sealant carriers copy every separation surface of sleeve, as well as the holes in the places of connection of the sleeve and pipeline.

Figure 2. Split sleeve for branch connection repairs

Figure 3. Branch connection with split sleeve

One of the most important requirements for the application of the sleeve as a permanent repair is the maximum allowable operating pressure (MAOP) of the sleeve. In this article, determination of the required sleeve wall thickness and pressure testing of the manufactured split sleeve are presented. 2. FINITE ELEMENT COMPUTATION

OF SPLIT SLEEVE WALL THICKNESS

Split sleeves for pipelines repairing can be in general considered as thin-walled pressure vessels. Since walls of the sleeve offer little resistance to bending, it can be assumed that the internal forces exerted on a given portion of the wall are tangent to the surface of the sleeve (vessel). The resulting stresses on an element of the wall will thus be contained in a plane tangent to the surface of the vessel [6]. Computation of

the stresses in the cylindrical and/or spherical pressure vessel is simple, but determination of stresses in the complicated geometry of the split sleeve for branch connection repairs is more difficult. In such cases, it is possible to use finite element (FE) analysis [7,8]. Simulation software ANSYS was applied to computation of the stresses in the wall of the sleeve, and according to results, wall thickness was determined. Numerical simulation was performed on the model representing a half of the sleeve with the symmetry plane crossing the axis of the branch connection. Prototype of the sleeve was designed for branch connection with outer diameter of Ø159 mm for header pipe and Ø60,3 mm for branch pipe. Angle between the pipes was 60°. As a material of the sleeve, S355 grade steel was applied. Nonlinear material elastic-plastic model for S355 grade steel was used to obtain more realistic results of FE analysis (Fig. 4). Several values of thickness and dimensions of sealant carriers were applied during thickness determination. Initial thickness was chosen according to wall thickness of practically used cylindrical split sleeves to 10 mm. Such thickness resulted in very high stresses in FE analysis (over 1000 MPa) and thickness had to be increased up to 16 mm. Initial models also did not contain sealant carriers. It was also consider that usage of the sealant carriers might be useful and next models also contained sealant carriers with thickness of 5 mm and length of 50 mm.


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Such thickness was also insufficient but length was not have very important role and could be reduced. Final dimensions of the sealant carriers was 8x35 mm.

Figure 4. Stress-strain diagram of S355 grade

steel used in FE analysis The 3D models prepared in Autodesk Inventor software was meshed in ANSYS by automatic

meshing function. Triangular and quadrilateral elements for 3D analysis was used to prepare the mesh due to increasing of the wall thickness up to 16 mm, and to consider presence of the stresses in the wall thickness. Boundary conditions of the computation are shown in Fig. 5. Connection B, C and D was fixed and plane A is symmetry plane of the model. Pressure with value of the 6,3 MPa was applied to each internal face of sleeve. Distribution of the equivalent stresses for the final dimensions of the sleeve and internal pressure 6,3 MPa are shown in the Fig. 6 and Fig. 7. Computation results showed that thickness of split sleeve 16 mm is sufficient. It was also demonstrated that sealant carriers serve not only to isolate internal space of sleeve during welding but also as the reinforcement of the sleeve against pressure.

Figure 5. Boundary conditions in FEM analysis

Figure 6. Equivalent stresses in the split sleeve – inner surface


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Figure 7. Equivalent stresses in the split sleeve – outer surface

3. MANUFACTURING OF THE SPLIT

SLEEVE Branch connection for application of split sleeve was made as a weldment of the pipes with dimensions of 159,0x4,5 mm and 60,3x4,0 mm for header pipe and branch pipe, respectively. Place of connection branch pipe with header is consider as an isolated hole and reinforcement of the hole needs to be assessed. According to EN 13480-3 standard [9], reinforcement with thickness of 4,5 mm and length of 35 mm should be used. For this purpose, steel plate with shape of ellipse (reinforcement pad) was used and welded to the header and branch pipe (Fig. 8a). Different manufacture processes and also semi- products were applied to parts of the sleeve. Cylindrical part was prepared by welding of end

plates to thick-walled pipe (thickness of 16 mm for each part). Both end plates are made of S355J2+N steel and material of the thick-walled pipe was S355J2H steel. Sphere-like part was made by milling of S355JR steel block to required shape and size. Machined part was after that split into two segments. Materials used in this type of construction have ensured weldability without additional conditioning. Manufactured parts of split sleeve are shown in Fig. 8b. After the parts were manufactured, parts of the split sleeve were welded by butt welds by manual metal arc technology (MMA). Whole sleeve was then welded by fillet girth welds to the branch connection.

a) b)

Figure 8. Manufactured branch connection (a) and split sleeve (b) before assembling 4. PRESSURE TESTS OF SPLIT SLEEVE Standardized pressure test can be performed according to several standards. For designed sleeve, hydrostatic pressure test was used in terms of EN 12 327 [10] and Slovak technical rule TPP 702 02 [11]. Testing procedure was

based on the filling the test section of pipe equipped with the repairing sleeve (Fig. 9a) with water and pumping the pressure up to a value that is higher than maximum allowable operating pressure (MAOP) and holding the pressure for a period of one and a half hours. According to the


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standards, value of the pressure should be higher than 1,5xMAOP. During the testing period, pressure decrease was measured by pressure gauge (Fig. 9b). Dimensions of the sleeve was designed to MAOP with value of 6,3 MPa and minimal testing pressure was proposed to 10 MPa. During the testing period, no significant decrease of the pressure was detected.

Pressure test to destruction was used to determine weak area of the branch connection with applied split sleeve. During the test, internal pressure was constantly increased to the destruction of the analysed sample. Destruction occurred at the internal gauge pressure 27,3 MPa (273 bar). The crack was situated on the flat surface of the sleeve (Fig. 10).

a) b)

Figure 9. Pressure test of the split sleeve for branch connection repairs: a) experimental setup; b) detail of pressure gauge with value of the pressure during standardised test

a) b)

Figure 10. Position (a) and detail (b) of the crack after pressure test to destruction 5. DISCUSSION Numerical computation of the split sleeve for branch connection repair shows importance of the designing phase during the manufacturing process mainly in case of the new repairing solutions and prototypes. Results of equivalent stresses leads to increasing of the wall thickness of the sleeve up to 16 mm (initial value was 10 mm). The reason is relatively complicated shape that was designed to ensure the possibility of sleeve installation and without unwanted increase in the sleeve volume (causing increase in the weight). Higher equivalent stresses than material Yield stress (355 MPa) might be observed in some areas after FE analysis. Such values was present on the sharp edges or in the

areas of the sealant carrier connection to the wall of sleeve. This increasing might be influenced by computational method. Equation describing static equilibrium are solved in the nodes of the mesh. After solving process, a post-processing follows, which is strongly dependent on the shape of the elements. Sharp edges might cause that created mesh contains elements, which can during post-processing lead to rapidly increased values of the stress. The main body of the sleeve (Fig. 7) shows presence of the stresses with values below material Yield stress initiated by MAOP. Thickness with value of 16 mm and sealant carriers with dimension of 8x35 mm are thus sufficient to withstand MAOP of the pipeline with value of 6,3 MPa.


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Two pressure tests were proposed to the manufactured prototype construction. First test was designed to verify the proposed dimensions. Standardized testing procedure selected to this purpose shows sufficient resistance during the loading of the sample by internal gauge pressure with value of 10 MPa. In addition, correctness of the manufacturing technique of the pipes and split sleeve was also verified as there was not detected leakage of the water. Second testing procedure was selected in order to obtain information about the weak places of the construction. Constantly increased internal gauge pressure leads to destruction and formation of the crack on the flat surface of the sleeve. This place (Fig. 10) is in good agreement with the maximum equivalent stresses of the sleeve main body in finite element computation (Fig. 7). Maximum measured gauge pressure (27,3 MPa) also pointed out a possibility of application of the sleeve with lower wall thickness in practical applications. 6. CONCLUSIONS New type of the split sleeve for branch connection repairing can bring decrease in the repairing costs compared to repairs by replacing of the damaged area with interruption of the gas supply or with bypass construction. Several conclusions can be stated from the computation of the wall thickness and pressure tests of the designed sleeve as follows: 1) Minimum required thickness and sealant

carriers’ dimensions for selected pipe dimensions are according to finite element computation 16 mm and 8x35 mm, respectively.

2) Designed construction and welding process satisfies conditions required by the standard EN 12 327 and Slovak technical rule TPP 702 02.

3) The weakest place of the construction is flat surface of the sleeve where the maximum stresses of the main sleeve body were computed and also crack after destruction pressure test was present.

Acknowledgement Research has been supported by Scientific Grant Agency of Ministry of Education of the Slovak Republic, grant KEGA 034ŽU-4/2015. Authors acknowledge the grant agency for support.

7. REFERENCES [1] EGIG: Gas Pipeline Incidents. 9th Report

of the European Gas Pipeline Incident Data Group (period 1970 – 2013), 2015.

[2] Gajdoš, Ľ.: Reliability of gas pipelines. ČVUT, Praha, Czech Republic, 2000. (in Czech)

[3] Batisse R.: Review of gas transmission pipeline repair methods, Safety, Reliability and Risks Associated with Water, Oil and Gas Pipelines. Springer, Dordrecht, 2007.

[4] Mičian M., Patek M., Sládek, A.: Concept of repairing branch pipes on high-pressure pipelines by using split sleeve, Manufacturing Technology, 14(1):60-66, 2014.

[5] Meško J., Fabian P., Hopko A., Koňár R.: Shape of heat source in simulation program SYSWELD using different types of gases and welding methods, Strojírenská technologie, 16(5):6-11, 2011.

[6] Beer F.P. et al.: Statics and Mechanics of Materials, McGraw-Hill, New York, 2011.

[7] Cep R., Janasek A., Cepova L., Hlavaty I.: Effect of post-welding heat treatment on secondary hardening of welded joints of Cr-Mo-V steel, Metal Science and Heat Treatment, 53(7-8):374-378, 2011.

[8] Zmindak M., Radziszewski L., Pelagic Z., Falat M., FEM/BEM Techniques for Modelling of Local Fields in Contact Mechanics, Communications 17(3):37-46, 2015.

[9] EN 13480-3 Metallic industrial piping. Part 3: Design and calculations, 2012.

[10] EN 12 327 Gas infrastructure. Pressure testing, commissioning and decommissioning procedures. Functional requirements, 2012.

[11] TPP 702 11 Repairs of high-pressure steel pipelines with maximal allowable operational pressure 40 bar including, 2011. (in Slovak)

Coresponding author: Marek Patek University of Žilina, Faculty of Mechanical Engineering, Department of Technological Engineering, Žilina, Slovak Republic Email: [email protected] Phone: +421 41 513 2771

Mašinstvo 1(13), 9 – 22, (2016) E. Ekinović, ….: RECONSTRUCTION OF CHANNELS…

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REKONSTRUKCIJA KANALA ZA ODVOĐENJE DIMNIH PLINOVA U TERMOELEKTRANI “KAKANJ”

RECONSTRUCTION OF CHANNELS FOR FLUE GASES DISCHARGE

IN THERMAL POWER PLANT „KAKANJ“ Elma Ekinovic, Nedim Hodžić, Almir Kahriman

University in Zenica, Zenica Bosnia and Hercegovina Ključne riječi: dimnjak, dimni kanali, dimni plinovi, termoelektrana Key words: chimney, flue channels, flue gases, thermal power plant Paper received: 15.02.2016 Paper accepted: 10.03.2016.

Stručni rad REZIME Pri sagorijevanju goriva u kotlovima Termoelektrane „Kakanj“ nastaju plinovi koji su nepoželjni za okolinu, ljude koji žive u okolini termoelektrane, kao i za floru i faunu. Da bi se zaštitila životna sredina treba uložiti mnogo napora i organizacionih aktivnosti i imati na raspolaganju značajna materijalna sredstva. Dimni plinovi koji nastaju procesom sagorijevanja goriva u kotlu se filtriraju, a zatim se pomoću plinovodnih kanala i dimnjaka ispuštaju u okoliš. Za ispuštanje prečišćenih plinova, u Termoelektrani „Kakanj“se već dugi niz godina koristi isključivo 300-metarski dimnjak. U toku remonta na postrojenju bloka 7 i rekonstrukcije 300-metarskog dimnjaka, koji su izvršeni u periodu septembar-decembar 2014. godine, bilo je potrebno preusmjeriti odvođenje dimnih plinova sa blokova 5 i 6 prema 100-metarskom dimnjaku. U ovom radu opisan je proces rekonstrukcije dimnih kanala i proračun radnih parametara 100-metarskog dimnjaka radi preusmjeravanja dimnih plinova ka istom.

Professional paper SUMMARY As the result of combustion process in boilers of the Thermal Power Plant „Kakanj“, flue gases develop, which are undesirable for the environment, for people living in the plant neighborhood and for flora and fauna. In order to perform environmental protection a lot of efforts and organizational activities should be put in action and significant resources should be made available. Flue gases from the plant boilers are filtered and discharged in the environment after passing flue channels and the chimney. The Thermal Power Plant „Kakanj“ has used 300-meter chimney for flue gases discharge for a long time. During the overhaul of block 7 and reconstruction of 300-meter chimney in period September-December 2014, it was necessary to redirect the flue gases from blocks 5&6 to the 100-meter chimney. This task required certain reconstruction of existing installation and calculation of 100-meter chimney capability. The performed flue channels reconstruction and calculation of operating parameters of 100-meter chimney are presented in this paper.

1. UVOD Tokom sagorijevanja goriva u kotlovima termoenergetskih postrojenja, kao nus-produkt nastaju plinovi koji su štetni za okoliš, ljude, kao i floru i faunu. Nakon filtriranja, ovi dimni plinovi se pomoću dimnjaka ispuštaju u okoliš. Dimnjaci su vertikalne građevinske konstrukcije cjevastog oblika koji se koriste za ispuštanje filtriranih dimnih plinova u atmosferu. Oni se razlikuju po svojim geometrijskim osobinama (širina, visina, debljina stijenke, itd.), vrsti materijala od kojih su napravljeni (kamen, cigla, čelik, armirani beton) i tako dalje, a sve to zavisi od njihove namjene.

1. INTRODUCTION During fuel combustion in boilers of thermal power plants, flue gases develop, which are harmful for the environment, for people around and for flora and fauna. After filtering, the flue gases are discharged through chimney. Chimneys are vertical pipe-like constructions that are used to release filtered flue gases into the atmosphere. There are great variation in the design of chimneys referring to their geometric characteristics (depth, height, wall thickness and so on), building material (stone, brick, steel, reinforced concrete) and so on, which depends on their purpose.


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Za potrebe odvođenja plinova nastalih u procesu sagorijevanja goriva u blokovima 5, 6 i 7 Termoelektrane „Kakanj“ koristi se dimnjak visine 300 m, slika 1. U neposrednoj blizini bloka 6 nalazi se dimnjak visine 100 metara. Tokom remonta na postrojenju bloka 7 i sanacije 300-metarskog dimnjaka, koji je obavljen u period septembar-decembar 2014. godine, bilo je neophodno da se koristi dimnjak visine 100 m. Zbog toga je bilo potrebno izvršiti njegovu djelomičnu rekonstrukciju, kao i rekonstrukciju plinovodnih kanala [1].

To discharge flue gases from blocks 5, 6 & 7, the Thermal Power Plant „Kakanj“ uses the 300-meter chimney, Fig. 1. In the vicinity of the block 6, there is an alternative 100-meter chimney. During the overhaul of block 7 and reparation of 300-meter chimney in period September-December 2014, it showed necessary to use the 100-meter chimney. For that purpose, it was required to reconstruct the 100-meter chimney and the flue gases channels, [1].

Slika 1. Termoelektrana „Kakanj“ Figure 1. Power Plant “Kakanj”

2. REKONSTRUKCIJA PLINOVODNIH KANALA Pri revitalizaciji elektrofiltera bloka 6, snage 110 MW, tokom 2012. godine, uklonjeni su tada korišteni dimni ventilatori zajedno sa pripadajućim plinovodnim kanalima na dionici od elektrofiltera do mjesta njihovog spajanja na zajednički kolektorski kanal. Isti su bili dotrajali i predstavljali su smetnju pri rekonstrukciji filtera bloka 6. Pri ugradnji novih kanala iza ventilatora bloka 6 nisu predviđena priključna mjesta, niti kanalski ogranci za korištenje 100-metarskog dimnjaka, koji se koristio prije izgradnje 300-metarskog dimnjaka 1988. godine. Također, nakon rekonstrukcije filtera na ovom bloku 2010. godine, ostali su nepromijenjeni neki dijelovi priključnih kanala bloka 5 na zajedničkom glavnom kanalu. Sistem odvođenja dimnih plinova prije rekonstrukcije 300-metarskog dimnjaka i remonta na postrojenju bloka 7 prikazan je na slici 2. Za sanaciju i održavanje 300-metarskog dimnjaka potrebno je isključenje iz procesa proizvodnje električne energije (totalni zastoj) sva tri bloka (5, 6 i 7).

2. RECONSTRUCTION OF THE FLUE GASES CHANNELS During 2012, when the revitalization of electro filter with power 110 MW in block 6 was done, the smoke fans and the associated pipeline on the section from the electro filters to the place of their connection to the common collector channel were removed. These fans were worn out and made obstruction to the reconstruction of filters of block 6. During installation of new channels behind the fans of block 6, the connection points or channel branches were not provided for the need to use the 100-meter high chimney, which was used before the construction of 300-meter chimney in 1988. Also, some parts of the block 5 channels connected to the common main channel remained unchanged after the reconstruction of filter of block 6 in 2010. The system for discharge of flue gases before the reconstruction of 300-meter chimney and reparation of the block 7 is shown in Fig. 2. During the repair and maintenance of 300-meter chimney, all three blocks (5, 6 and 7) should be stopped and excluded from the production of electricity (deadlock).


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Pošto prekid proizvodnje nije bio ekonomski dopustiv, nametnuo se zahtjev da se izvrši priključenje izlaznih plinovodnih kanala blokova 5 i 6 na ranije korišteni 100-metarski dimnjak bloka 6 i time omogući rad postrojenja, a što je zahtijevalo i rekonstrukciju postojećih plinovodnih kanala [1]. Proces rekonstrukcije plinovodnih kanala termoenergetskih postrojenja predstavlja veoma zahtjevan poduhvat. Zbog toga su izvršene detaljne pripreme koje su obuhvatale analizu potrebnog stručnog kadra, analizu potrebne dokumentacije prethodnog i stanja nakon rekonstrukcije, analizu mjesta rekonstrukcije sistema, analizu raspoloživog prostora, analizu potrebne opreme i tako dalje. Pri tome se trebalo težiti tome da rekonstrukcija bude optimalna i da se što manje naruši postojeće stanje. Izgradnja novih kanala trebala bi da doprinese efikasnijem radu blokova 5 i 6.

As this is not an economical solution, the task have been given to specialists to make possible the work and production of electricity in blocks 5 and 6 by using the available 100-meter chimney and flue gases pipeline reconstruction, [1]. The reconstruction of flue gases channels in thermal power plants is a very complex task. Therefore, very detailed preparations were made, which included the analysis of qualified specialists, analysis of the necessary documentation, analysis of the system reconstruction location, analysis of the available space and necessary equipment, and so on. Also, the task was to make an optimal reconstruction and to disturb the status quo the least possible. Construction of new channels should also contribute to more efficient work of the blocks 5 and 6.

Slika 2. Odvođenje dimnih plinova kroz 300-metarski dimnjak – shema (normalni rad) Figure 2. Discharge of flue gases through 300-meter chimney – scheme (normal operating regime)

Da bi se spriječio protok plinova prema 300-metarskom dimnjaku, ugrađena je klapna dimenzija 3800x5400 mm kod kompenzatora sa oznakom KO31, slika 3. Kod stuba K8 na postojećem kanalu bilo je potrebno ugraditi klapnu dimenzija 2790x3800 mm, da bi se spriječio protok dimnih plinova bloka 5 postojećim kanalom prema 100-metarskom dimnjaku. Spojevi novog kanala bloka 5 u postojeće kanale istog izvedeni su između stubova K8-K10 na postojećem kanalu Φ 3800x5400 mm. Novi spojevi su usmjereni vertikalno naviše. Na zahtjev investitora, a i zbog troškova, trasa novih kanala bloka 5 definirana je iznad postojećih kanala. Novi zbirni kanal bloka 5 nalazi se iznad postojećeg kanala i kod stubova K3-K4 skreće u pravcu bližeg otvora na 100-metarskom dimnjaku.

To prevent the gas flow to the 300-meter chimney, the flap of dimensions 3800x5400 mm was built-in near the KO31 compensator, Fig.3. Also, a flap of dimensions 2790x3800 mm needed to be installed in the existing channel near the column K8 to prevent the flue gas flow of block 5 through the existing channel to 100-meter chimney. The new channels of the block 5 join the existing channels between the columns K8-K10 of the existing channel Φ 3800x5400 mm. The new joints are directed vertically upward. At the request of the investor, and because of the costs, the route of the new channels of the block 5 was set above the existing channels. The new collection channel of the block 5 is located above the existing channels and at the location of columns K3-K4 turns in the

BLOCK 7

FLUE GASES CHANNEL

BLOCK 5 BLOCK 6

CHIMNEY 100-METER

V V V V


12

Jednim dijelom trasiran je iznad postojećeg kanala bloka 6, a zatim se spušta i spaja u dimnjak. Ovo rješenje ekonomski je prihvatljivije od rješenja da se kanal bloka 5 spaja u dalji otvor na dimnjaku. Osim toga, postojeći kanal bloka 6 je bilo nemoguće spojiti u bliži otvor na dimnjaku zbog veoma malog raspoloživog prostora. Opisanim rješenjem je smanjena dužina kanala bloka 5, a povećana dužina kanala bloka 6, tako da je ukupna razlika u otporima proticanju dimnih plinova novim kanalima smanjena, slika 3.

direction to the nearest opening of the 100-meter chimney. It is partly traced over the existing channel of block 6, then descends and joins the chimney. This solution is more economical than to connect the channel of block 5 to the farther chimney opening. In addition, the existing channel of the block 6 was impossible to connect to the closer hole because of the small space available. This solution shortened the length of the channel of block 5 and increased the length of the block 6 channel. This resulted in reduced flow resistance of the flue gas channels, Fig. 3.

Slika 3. Odvođenje dimnih plinova kroz 100-metarski dimnjak – shema (tokom zastoja 300-metarskog dimnjaka)

Figure 3. Discharge of flue gases through 100-meter chimney – scheme (during deadlock of 300-meter chimney)

Strujanje dimnih plinova iz bloka 6 prema 300-metarskom dimnjaku u postojeći kanal kod stubova K3-K4 blokirano je ugradnjom klapne dimenzija 2790x3800 mm. Novi kanal dimnih plinova bloka 6 je spojen na postojeći kanal između stubova K1-K2 i K3-K4 na mjestu gdje on mijenja pravac za ugao 90°. Od mjesta spoja, kanal ide novom trasom tako da se mora napraviti čelična konstrukcija do spoja kanala u 100-metarski dimnjak. Visina otvora na dimnjaku IV etape se povećala sa 2800 mm na 4335 mm. Plinovodni kanali su napravljeni od konstrukcionog čelika sa izvedenom AKZ zaštitom i izolirani tervolom debljine 150 mm uz zaštitu Al-limom debljine 1 mm. Ispred svih klapni na kanalima su ugrađeni revizioni otvori. Sa strane kanala, gdje je pogon klapni,

The flow of flue gases from block 6 to the 300-meter chimney is blocked by installing a flap of dimensions 2790x3800 mm at the location of columns K3-K4. The new flue gas channel of block 6 is connected to the existing channel between the columns K1-K2 and K3-K4 at point where it changes direction for 90o angle. Behind the joining point, the channel goes a new route and a steel construction must be made till the opening of the 100-meter chimney. The height of the chimney openings at the IV stage is extended from 2800 mm to 4335 mm. Flue gas channels are made of structural steel with a built-in AKZ protection and insulated with tervol of 150 mm thickness and with Al-sheet protection of 1 mm thickness. The inspection holes are made in channels in front of all flaps. The installation of ladders and

CHIMNEY 300-METER

BLOCK 7

NEW CHANNEL OF

BLOCK 6

OPEN CHANNEL CLOSED CHANNEL

BLOCK 5 BLOCK 6

CHIMNEY 100-METER

NEW CHANNEL OF

BLOCK 5

FLAP 3800 x 5400 mm

V V V V

FLAP 2790 x 3800 mm

K8 K4 K3

K1 K2

K10

OLD CHANNEL

KO31


13

predviđena je ugradnja penjalica i podesta sa ogradom, kako bi se moglo prići klapnama i revizionim otvorima. Zavareni i prirubnički spojevi na kanalima moraju biti nepropusni, tako da je presisavanje zraka u dimnim plinovima manje od 0,5% što se utvrđuje mjerenjem količine CO2. Novoprojektirani kanali su odvojeni od postojećih kanala 700 mm po visini, tako da se nesmetano mogu ugraditi noseća čelična konstrukcija, kompenzatori, klapne, termoizolacija i prirubnički spojevi kanala. Kanali su dimenzionirani prema projektiranim pogonskim parametrima sa ugrađenim pokretnim osloncima i kompenzatorima [1]. 3. PRORAČUN RADNIH PARAMETARA

100-METARSKOG DIMNJAKA 3.1. Polazni podaci Na osnovu tehničkih podataka i crteža dostavljenih od strane JP Elektroprivreda BiH d.d. Sarajevo - Podružnica Termoelektrana „Kakanj“, bilo je potrebno povezati dimne kanale bloka 5 i bloka 6 na dimnjak prečnika 6,5 m i visine 100 m, radi nesmetanog rada ova dva bloka u toku rekonstrukcije na bloku 7 i 300-metarskom dimnjaku. Za rad kotlova blokova 5 i 6 koristi se ugalj iz rudnika „Srednja Bosna“, donje toplotne moći 9,8÷16,7 MJ/kg i ukupne vlažnosti 8÷26 %. Sastav produkata sagorijevanja je sveden na suhe produkte i dat je u tabeli 1 (čvrsta faza do 10 mg/m3). Temperatura dimnih plinova na izlazu iz kotlova je tp=200°C, pri spoljnoj projektnoj temperaturi tamb=-18°C. Osnovni geometrijski parametri dimnjaka su: prečnik Dc=6,5 m, visina Hc=100 m, geodezijska visina dimnjaka Hg=235 m. Osnovni zadatak u okviru rekonstrukcije i proračuna 100-metarskog dimnjaka bio je da se odredi pad pritiska na putanji dimnih plinova pri radu blokova 5 i 6 i pri radu oba bloka zajedno.

landings with a fence should be provided at the flaps drive location, in order to approach and control the flaps and the inspection openings. Welded and flanged joints of the channels must be hermetically sealed so that the flue gases leakage is less than 0,5%, which will be determined by measuring the CO2 quantity. The newly designed channels are separated from the existing channels by 700 mm in height, so that all steel structures, expansion joints, valves, insulation and flanged channels can be freely installed. The channels are designed according to the projected operating parameters with embedded mobile supports and joints [1].

3. THE CALCULATION OF 100-METER CHIMNEY OPERATING PARAMETERS 3.1. Input data Based on the technical data and drawings submitted by JP Elektroprivreda BiH dd Sarajevo – Thermal Power Plant "Kakanj", the task was to connect the flue gases channels from blocks 5 and 6 to the 100-meter chimney of diameter of 6.5 m, for undisturbed operation of the two blocks during the reconstruction of the block 7 and 300-meter chimney. For the operation of boilers in blocks 5 and 6, the coal from the mine "Srednja Bosna" is used with lower heating value of 9,8÷16,7 MJ/kg and total humidity 8÷26%. The composition of the combustion products reduced to a dry product (solids to 10 mg/m3) is given in Tab. 1. The temperature of flue gases leaving the boilers is tp=200°C, under the design ambient temperature of tamb = -18°C. The basic geometric parameters of the chimney are: diameter Dc=6,5 m, height Hc=100 m, geodesic height of the chimney Hg=235 m. The main task in the reconstruction and calculation of 100-meter chimney was to determine the pressure drop in the path of the flue gases during the operation of blocks 5 and 6 separately and both blocks together.

Tabela 1. Sastav produkata sagorijevanja Table 1. The composition of the combustion products Komponenta / Component CO2 O2 N2 SO2

Molski udio / Molar proportion y, % 13÷15 4÷8 81 0.28 Volumenski protok produkata sagorijevanja pri normalnim uvjetima je:

Volume flow of the combustion products under normal conditions is:


14

NpV ,5,& = 136 m3/s = 489 600 m3/h – za blok 5,

NpV ,6,& = 151 m3/s = 543 600 m3/h – za blok 6,

odnosno, zbirno NpV ,& = 287 m3/s = 1 033 200 m3/h.

3.2. Proračun svojstava produkata

sagorijevanja Molarna masa produkata sagorijevanja iznosi Mp=29,7 kg/kmol, a specifična masa (gustina) produkata sagorijevanja pri normalnim uvjetima (p=101 325 Pa, t=0°C) je ρp,N = 1,326 kg/m3, [2]. Ostala termofizička svojstva produkata sagorijevanja u funkciji od temperature su data u tabeli 2, prema [2]. Maseni protok produkata sagorijevanja se izračunava prema izrazu

ppp Vm && ρ= , (1)

što daje vrijednosti: 5,pm& = 180 kg/s za blok 5,

6,pm& = 200 kg/s za blok 6, odnosno, zbirno pm& = 380 kg/s. Volumenski protok produkata sagorijevanja pri radnim uvjetima (ρp=0,756 kg/m3 i tp=200°C) se također analogno izračunava prema jednačini (1) i iznosi:

5,pV& =239 m3/s=860 400 m3/h za blok 5,

6,pV& =265 m3/s=954 000 m3/h za blok 6, odnosno, zbirno

pV& =504 m3/s=1 814 400 m3/h.

NpV ,5,& = 136 m3/s = 489 600 m3/h for block 5,

NpV ,6,& = 151 m3/s = 543 600 m3/h for blok 6,

which gives the total sum of NpV ,

& = 287 m3/s = 1 033 200 m3/h.

3.2. Calculation of combustion products

properties Molar mass of the combustion products is Mp=29,7 kg/kmol, and the density of combustion products under normal conditions (p=101 325 Pa, t=0°C) is ρp,N = 1,326 kg/m3, [2]. The other thermo-physical properties of combustion products as a function of temperature are given in Tab. 2 according to [2]. The mass flow of combustion products is calculated according to the formula

ppp Vm && ρ= , (1)

which gives the values: 5,pm& = 180 kg/s for block 5,

6,pm& = 200 kg/s for block 6, i.e. the total sum is pm& = 380 kg/s. The volume flow of combustion products under operating conditions (ρp=0,756 kg/m3 and tp=200°C) was also calculated by the equation similar to the Eq.(1) and this gives:

5,pV& =239 m3/s=860 400 m3/h for block 5,

6,pV& =265 m3/s=954 000 m3/h for block 6, i.e. the sum is

pV& =504 m3/s=1 814 400 m3/h. Tabela 2. Osobine produkata sagorijevanja u funkciji od temperature Table 2. Properties of combustion products as a function of temperature

Temperatura/ Temperature

Gustina/ Density

Specifični toplotni kapacitet/

Specific heat capacity

Toplotna provodnost/

Thermal conductivity

Dinamički viskozitet/ Dynamic viscosity

Prandtlov broj/

Prandtl number

t / oC ρp / kg/m3 cp / J/kgK λp / mW/mK μp / μPas Prp 100 0,958 1041 29,7 19,9 0,699 200 0,756 1057 37,1 24,1 0,684 300 0,624 1072 44,2 27,8 0,673

3.3. Proračun toplotnih gubitaka i pada

pritiska kroz dimnjak Proračun toplotnih gubitaka i pada pritiska kroz dimnjak izvršen je prema literaturi [3].

3.3. Calculation of heat loss and pressure drop through the chimney

The calculation of heat loss and pressure drop through the chimney was made according to the reference [3].


15

Srednja površina dimnjaka iznosi ccc HDS π= =2042 m2. (2) Srednja brzina strujanja produkata sagorijevanja kroz dimnjak je definirana izrazom

4

2c

p

pp D

mw

πρ

&= . (3)

Rejnoldsov broj izračunava se na osnovu izraza

p

pcpp

DwRe

μρ

= . (4)

gdje je pμ dinamički viskozitet produkata sagorijevanja. Koeficijent prelaza toplote između produkata sagorijevanja i unutrašnje površine donjeg dijela dimnjaka određen je izrazom

The mean cross-sectional area of the chimney is

ccc HDS π= =2042 m2. (2)

The mean velocity of the combustion products flow through the chimney is defined by the expression

4

2c

p

pp D

mw

πρ

&= . (3)

The Reynolds number is calculated on the basis of the expression

p

pcpp

DwRe

μρ

= . (4)

where pμ is the dynamic viscosity of the combustion products. The coefficient of heat convection between the combustion products and the inner surface of the lower part of the chimney is defined as

( )670670

420750 11800370,

s

r

,

ef,c

c,p

,p

c

pin H

DPrRe,D ⎟⎟

⎠

⎞⎜⎜⎝

⎛⋅

⎥⎥

⎦

⎤

⎢⎢

⎣

⎡

⎟⎟⎠

⎞⎜⎜⎝

⎛+⋅⋅−⋅⋅=

ξξλ

α , (5)

gdje su, prema [4], koeficijent otpora trenja za glatku hidrauličku cijev ξs = 0.015, a ξr = 0,020 za hrapavu hidrauličku cijev (za usvojenu apsolutnu hrapavost od 5 mm). Koeficijent prelaza toplote između okolnog zraka i spoljašnje strane izolacije iznosi αout=23W/m2K, pri čemu je usvojena brzina vjetra od 4 m/s, [3]. Koeficijent prolaza toplote izračunava se prema izrazu

inz

z

out

ck

αλδ

α11

1

++= . (6)

gdje je: δz – debljina stijenke zida, λz – koeficijent provođenja toplote (kondukcije) kroz zid. Broj jedinica prijenosa definiran je izrazom

pp

cc

cmSkNTU⋅⋅

=&

. (7)

where, according to [4], the coefficient of friction for smooth hydraulic pipe is ξs = 0,015, and for rough hydraulic pipe ξr = 0,020 (for the adopted absolute roughness of 5 mm). The coefficient of heat convection between the ambient air and the outside of the insulation is αout=23W/m2K, where the adopted wind speed is 4 m/s, [3]. The heat transfer coefficient is calculated according to the formula

inz

z

out

ck

αλδ

α11

1

++= . (6)

where: δz – wall thickness, λz – coefficient of heat conduction through the wall. The number of transmission units is defined by

pp

cc

cmSkNTU⋅⋅

=&

. (7)


16

Temperatura produkata na izlazu iz dimnjaka se izračunava prema izrazu

( ) ( )NTUexptttt ambpambout,p −⋅−+= . (8)

Temperatura unutrašnje strane zida dimnjaka na vrhu dimnjaka definirana je izrazom

( )ambout,pin

cout,pout,w ttktt −⋅−=

α . (9)

Pad pritiska usljed trenja u dimnjaku, za koeficijent otpora trenja koji prema [3] iznosi ξr=0,033, izračunava na osnovu izraza

2

2pp

c

crfr

wDHp

⋅⋅⋅=Δρ

ξ . (10)

The flue gasses temperature at the chimney outlet is calculated by

( ) ( )NTUexptttt ambpambout,p −⋅−+= . (8)

The temperature of the inner side of the chimney wall at the top is given by

( )ambout,pin

cout,pout,w ttktt −⋅−=

α . (9)

The pressure drop due to friction in the chimney with the coefficient of friction ξr=0,033 (according to [3]) can be calculated by

2

2pp

c

crfr

wDHp

⋅⋅⋅=Δρ

ξ . (10)

Tabela 3. Rezultati proračuna 100-metarskog dimnjaka Table 3. The results of calculation of 100-meter chimney

Veličina/ Quantity

Mjerna jedinica/ Units

Blok 5 / Block 5

Blok 6 / Block 6

Blokovi 5 i 6 / Block 5 & Block 6

NpV ,& m3/h 489 600 543 600 1 033 200

pm& kg/s 180 200 380

pV& m3/h 239 265 504 wp m/s 7,20 7,98 15,2 Rep - 1 470 000 1 630 000 3 100 000 αin W/m2K 14,2 15,6 28,1 kc W/m2K 0,526 0,528 0,536

NTU - 0,00564 0,00510 0,00272 tp,out oC 198,8 198,9 199,4 tw,out oC 190,8 191,6 195,3 Δpfr Pa 10 12 44 Δpcd Pa 599 599 599 Δpdin Pa 20 24 87 pef Pa 569 563 468

Pri gustini okolnog zraka ρamb = 1,365 kg/m3, vuča dimnjaka (razlika ulaznog i izlaznog pritiska) je

( ) ( )pambgccd HHgp ρρ −⋅+⋅=Δ . (11) Pad dinamičkog pritiska na izlazu iz dimnjaka definiran je izrazom

2

2pp

dinw

p⋅

=Δρ

. (12)

Efektivni podpritisak u podnožju (korijenu)

With the ambient air density ρamb=1,365 kg/m3, the chimney draft (input and output pressure difference) is

( ) ( )pambgccd HHgp ρρ −⋅+⋅=Δ . (11)

The dynamic pressure drop at the chimney outlet is given by

2

2pp

dinw

p⋅

=Δρ

. (12)

The effective pressure at the bottom of the


17

dimnjaka je

dinfrcdef pppp ΔΔΔ −−= . (13) Rezultati proračuna 100 metarskog dimnjaka pojedinačno za blok 5 i 6, i ukupni rezultati za oba bloka, dati su u tabeli 3. 3.4. Proračun pada pritiska u kanalu od tlačne klapne do dimnjaka Pad pritiska u kanalu se izračunava prema izrazu

∑∑==

⋅=Δ=Δ

n

i

i,ppi

n

ii

wpp

1

2

1 2ρ

ζ , (14)

gdje su:

pρ - gustina produkata sagorijevanja,

i,pw [m/s] - brzina toka produkata sagorijevanja u i-toj dionici,

iζ - ukupni koeficijent otpora toku u i-toj dionici računat prema formuli

∑=

+=m

kk

ie

iii D

L

1,ξλζ , (15)

gdje su: λi =0,033 –koeficijent linijskog otpora trenja, prema [4], Li [m] -dužina i-te dionice cjevovoda, De,i [m] - ekvivalentni dijametar i-te dionice,

∑=

m

kk

1

ξ - suma lokalnih otpora duž i-te dionice

plinovoda. Prvi dio ukupnog otpora u jednačini (15) predstavlja linijski otpor usljed trenja, to jest

ie

iiifr D

L,

, λζ = . (16)

Ekvivalentni prečnik dionice je u slučaju kružnog poprečnog presjeka jednak unutrašnjem prečniku, a u slučaju pravougaonog poprečnog presjeka dimenzija AxB ekvivalentni prečnik je

250

6250

31 ,

,

i,e )BA()BA(,D

+⋅

= . (17)

chimney is

dinfrcdef pppp ΔΔΔ −−= . (13)

The results of calculation of 100-meter chimney, for blocks 5 and 6 partially and summary, are given in Tab. 3.

3.4. Calculation of the pressure drop in the channel from the pressure flap to the chimney The pressure drop in the channel is calculated according to the formula

∑∑==

⋅=Δ=Δ

n

i

i,ppi

n

ii

wpp

1

2

1 2ρ

ζ , (14)

where is: pρ - density of combustion products,

i,pw [m/s] - flow velocity of the combustion products in the ith pipeline section,

iζ - total coefficient of flow resistance in the ith pipeline section calculated by

∑=

+=m

kk

ie

iii D

L

1,ξλζ , (15)

in which: λi =0,033 - coefficient of line resistance friction, according to [4], Li [m] - the length of the ith pipeline section, De,i [m] - equivalent diameter of the ith section,

∑=

m

kk

1

ξ - sum of local resistances along the ith

pipeline section. The first part of the total resistance in Eq.(15) represents the line resistance due to friction, i.e.

ie

iiifr D

L,

, λζ = . (16)

The equivalent diameter of the pipeline section in the case of circular cross-section is equal to the internal pipe diameter, and in the case of the rectangular cross-section AxB the equivalent diameter is

250

6250

31 ,

,

i,e )BA()BA(,D

+⋅

= . (17)


18

3.4.1. Proračun pada pritiska za blok 5 do dimnjaka Proračun pada pritiska za blok 5 do dimnjaka je dat za lijevi kanal u tabeli 4. Ukupan pad pritiska u kanalima prirubnice iza tlačne klapne do dimnjaka iznosi ∆pblock 5=3038 Pa. 3.4.2. Proračun pada pritiska za blok 6 do dimnjaka Vrijednosti protoka, brzine strujanja i pada pritiska produkata sagorijevanja za blok 6 do dimnjaka dobijene proračunom po dionicama su date u tabeli 5. Ukupan pad pritiska u kanalima prirubnice iza tlačne klapne do dimnjaka iznosi ∆pblock 6=3524 Pa. 3.4.3. Analiza rezultata proračuna Zbirni rezultati proračuna dati u tabeli 6 pokazuju da je veći pad pritiska od tlačne klapne do dimnjaka na bloku 6 nego na bloku 5. Ovo je logično, jer su dimovodni kanali bloka 6 veće dužine u odnosu na kanale bloka 5. Zbog toga će na bloku 6 biti potreban veći dio napora ventilatora za savladavanje gubitka pritiska od tlačne klapne do izlaza iz dimnjaka. Brzine strujanja produkata sagorijevanja u dimnjaku i dimnim kanalima dati su u tabeli 7.

3.4.1. Calculation of pressure drop for block 5 to the chimney The pressure drop for block 5 to the chimney for the left channel is given in Tab.4. The total pressure drop from the flange behind the pressure flap to the chimney is ∆pblock 5=3038 Pa. 3.4.2. Calculation of pressure drop for block 6 to the chimney The values of flow, flow velocity and pressure drop for block 6 to the chimney calculated by pipeline sections are given in Tab. 5. The total pressure drop from the flange behind the pressure flap to the chimney is ∆pblock 6=3524 Pa. 3.4.3. The analysis of calculation results Results in Tab. 6 show that the pressure drop from the pressure flap to the chimney is higher in block 6 than in block 5. It is logical, because the flue gas channels of block 6 are longer than those of block 5. Therefore, a higher part of the fan effort will be required on the block 6 to overcome the pressure loss from pressure flap to the chimney outlet. The velocity of combustion products flows in the chimney and the flue channels is given in Tab. 7.

Tabela 4. Protok, brzina toka i pad pritiska produkata sagorijevanja po sekcijama (blok 5) Table 4. Flow, flow velocity and pressure drop of the combustion products per sections (block 5)

Br. / No.

Sekcija plinovoda / Pipeline section Otpori / Resistances wprod,i

[m/s] ∆pi

[Pa]

1

Od prirubnice iza tlačne klapne do skretanja naviše / From the flange behind the pressure flap to upturns 1) Protok /Flow: 245 000 m3/h, 2) L1=13 m, 3) De,1=2,13 m, 4) Poprečni presjek / Cross-section: 2700 x 1350 mm

Trenje / Friction: ζfr,1=0,20

30,5 1674

Klapna / Flap: ξ1=0,10

Oštro skretanje prema gore / Sharp turning upward: ξ2=4,47

UKUPAN OTPOR U SEKCIJI BR. 1 / TOTAL RESISTANCE IN SECTION NO. 1:

1ζ =4,77

2

Od skretanja naviše do uključenja desnog kanala / From upturns to the right channel connecting 1) Protok /Flow: 245 000 m3/h, 2) L2=16 m, 3) De,2=2,13 m, 4) Poprečni presjek / Cross-section: 2700 x 1350 mm


30,5 87 Bez lokalnih otpora / No local resistances


2ζ =0,25


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3

Od uključenja desnog kanala do dimnjaka / From the right channel connecting to the chimney 1) Protok /Flow: 490 000 m3/h, 2) L3=50 m, 3) De,3=3,06 m, 4) Poprečni presjek / Cross-section: 2700 x 2700 mm


30,5 1277

Spoj lijevih i desnih kanala / Connection of the left and right channels: ξ1=1

Spuštanje / Lowering 2 x 30°: ξ2=0,12+0,12

Skretanje / Turning 90°: Luk / Arch r/D=1: ξ3=0,25+0,25 Skretanje / Turning 30°: ξ4=0,16

Ulaz u dimnjak / Chimney entrance: ξ5=1,2 UKUPAN OTPOR U SEKCIJI BR. 3 /

TOTAL RESISTANCE IN SECTION NO. 3: 3ζ =3,64

Tabela 5. Protok, brzina toka i pad pritiska produkata sagorijevanja po sekcijama (blok 6) Table 5. Flow, flow velocity and pressure drop of the combustion products per sections (block 6)

Br. / No.

Sekcija plinovoda / Pipeline section Otpori / Resistances wprod,i

[m/s] ∆pi

[Pa]

1

Od prirubnice iza tlačne klapne do spajanja lijevih i desnih kanala / From the flange behind the pressure flap to the left and right channels connection 1) Protok /Flow: 271 500 m3/h, 2) L1=13 m, 3) De,1=2,13 m, 4) Poprečni presjek / Cross-section: 2700 x 1350 mm


33,8 288

Klapna / Flap: ξ1=0,10

Spoj kanala / Connection: ξ2=0,37


1ζ =0,67

2

Od spoja kanala do dimnjaka / From the connection of channels to the chimney 1) Protok /Flow: 543 000 m3/h, 2) L2=40 m, 3) De,2=3,06 m, 4) Poprečni presjek / Cross-section: 2700 x 2700 mm


33,8 3236

Skretanje / Turning 90°, Luk / Arch r/D=1: ξ1=0,25

Skretanje / Turning 30°: ξ2=0,16

Skretanje / Turning 90°, Luk / Arch r/D=0,678: ξ3=1

Oštro skretanje prema gore / Sharp turning upward:

ξ4=4,47 Ulaz u dimnjak / Chimney entrance:

ξ5=1,2 UKUPAN OTPOR U SEKCIJI BR. 2 /

TOTAL RESISTANCE IN SECTION NO. 2: 2ζ =7,51


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Tabela 6. Zbirni rezultati proračuna pada pritiska Table 6. Summary of pressure drop calculations

Veličina / Quantity Radni režim / Operating regime

Blok 5 / Block 5

Blok 6 / Block 6

Blokovi 5 i 6 / Block 5 and 6

Pad pritiska od tlačne klapne do dimnjaka [Pa] / Drop of pressure from the pressure flap to the chimney [Pa] 3038 3524 3524

Efektivni pritisak na dnu dimnjaka [Pa]/ Effective pressure at the chimney bottom [Pa] 569 563 468

Potrebni napor ventilatora za savladavanje gubitka pritiska od tlačne klapne do izlaza iz dimnjaka [Pa]/ Necessary fan exertion to overpower the pressure loss from the pressure flap to the chimney outlet [Pa]

2469 2961 3056

Preporučena brzina strujanja produkata sagorijevanja u dimnjacima je 10 m/s. Kada rade oba bloka (5 i 6), brzina strujanja u dimnjaku se povećava na 15,2 m/s. To je logično jer se količina produkata sagorijevanja povećava skoro dvostruko. Brzina produkata sagorijevanja u kanalima ostaje približno ista i nakon rekonstrukcije, jer se oni u kanalima nezavisno kreću.

The recommended velocity of combustion products in chimneys is 10 m/s. The velocity of the flow in chimney increases to 15.2 m/s when both blocks 5 and 6 work. It is logical because the amount of combustion products increase approximately to double. The speed of the combustion products in the channels remains almost the same after the reconstruction, because they move independently through the channels.

Tabela 7. Brzina toka produkata sagorijevanja u dimnjaku i u dimnim kanalima Table 7. The velocity of combustion products flows in the chimney and the flue channels

Brzina toka / Velocity of flow

Radni režim / Operating regime Blok 5 / Block 5

Blok 6 / Block 6

Blokovi 5 i 6 / Block 5 and 6

U dimnjaku / In chimney [m/s] 7,20 7,98 15,2 U kanalima / In channels [m/s] 30,5 33,8 30,5 ÷ 33,8

4. ZAKLJUČAK Proces rekonstrukcije plinovodnih kanala blokova 5 i 6 Termoelektrane „Kakanj“ predstavljao je veoma zahtjevan poduhvat. Zbog toga je bilo potrebno izvršiti detaljne pripreme koje su obuhvatale analizu potreba za stručnim kadrom, dokumentacijom i neophodnom opremom, kao i analizu mjesta rekonstrukcije, raspoloživog prostora i drugo. Pri tome se morala obratiti pažnja na to da rekonstrukcija bude optimalna u smislu što manjeg narušavanja postojećeg stanja. Izgradnja novih kanala trebala je također da doprinese efikasnijem radu blokova 5 i 6. Rekonstrukcija prezentirana u ovom radu ostvarila je navedene ciljeve. Proračunom parametara toka kroz 100-metarski dimnjak bloka 6 pokazano je da se on može koristiti kao alternativa u slučaju remonta na postrojenju bloka 7 i rekonstrukcije 300-metarskog dimnjaka. Izračunati gubici pritiska od tlačne

4. CONCLUSION The process of reconstruction of the gas channels of blocks 5 and 6 of the Thermal Power Plant "Kakanj" was a very challenging undertaking. Therefore, it was necessary to make detailed preparations, which included the analysis of needs for qualified specialists, technical documentation and necessary equipment, as well as the analysis of location, available space and so on. Special attention had to be put on to achieve an optimal reconstruction in a sense to make the least possible perturbation of the present state. Also, the construction of new channels was aimed to contribute to the efficient work of blocks 5 and 6. The reconstruction presented in this paper fulfilled all these objectives. Calculation of flow parameters through the 100-meter chimney proved that it could be used as an alternative chimney in case of the block 7


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klapne do izlaza iz dimnjaka, koji iznose približno 2500 Pa za blok 5 i 2960 Pa za blok 6, ukazuju na to da postojeći ventilatori imaju potrebnu snagu i kapacitet da se bez problema transportuje cjelokupna količina produkata sagorijevanja kada rade blokovi 5 i 6 i nije potrebna ugradnja novih ventilatora. Dakle, može se zaključiti da blokovi 5 i 6 mogu bez problema raditi kada su priključeni na dimnjak bloka 6 visine 100 metara.

repair and the 300-meter chimney reconstruction. The calculated pressure loss from the pressure flap to the chimney outlet, in amount of approximately 2500 Pa for block 5 and 2960 Pa for block 6, indicated that the existing fans had the necessary power and capacity to easily transport the entire quantity of combustion products from blocks 5 and 6 and that installation of new fans was not necessary. Thus, we can conclude that blocks 5 and 6 can easily work when connected to the 100-meter chimney of block 6.

5. LITERATURA - REFERENCES [1] Kahriman, A.: Proces odstranjivanja

čvrstih čestica iz dimnih plinova pomoću vrećastih filtera na blokovima 5 i 6 u TE „Kakanj“, Diploma paper, Mašinski fakultet, Zenica, 2015.

[2] Grupa autora: Osnovne tablice termofizičkih osobina produkata sagorijevanja, TE„Kakanj“, Kakanj, 2011.

[3] Grupa autora: Pogonska uputstva za proračun dimnjaka u termoelektranama, TE„Kakanj“, Kakanj, 2012.

[4] Grupa autora: Tablice koeficijenata trenja za pojedine oblike tijela, TE „Kakanj“, Kakanj, 2011.

Corresponding author: Elma Ekinović, University of Zenica Faculty of Mechanical Engineering E-mail: [email protected], Phone:+387 32 449136

MAIN TOPICS 1. MANUFACTURING TECHNOLOGIES AND MATERIALS Assembly and Disassembly; Machining, Nonconventional Machining, Tools, High Speed Machining; Dry Cutting, MQL Machining, High Performance Machining, Rapid Prototyping, Micromachining, Manufacturing Processes, Welding Processes; Plastic Forming Processes; Materials; Engineering of Polymers; Powder Metallurgy; Measuring; Thin & Thick Coatings; Surface Engineering; Molding Processes; CAM technologies; ...other subtopics 2. INDUSTRIAL ENGINEERING Diagnostic; Expert Systems; Autonomous Systems; Environmental Design; Reengineering; Knowledge Based Systems; Robot Applications; Mobile Robots; Optimizations, Reliability, Safety, Production Systems, Agile Manufacturing, Concurrent Manufacturing; Control, Flexible Manufacturing Systems; Hybrid Manufacturing Systems; CAP technologies; CIM technologies; Knowledge Management, Project Management, Production Management Systems, Quality Management, TQM, Maintenance, Nondestructive Testing, Operational Research Applications in Production, Scheduling, Supply Chain Management, Logistics, Electrical Engineering, Power Systems, Energetic; Ecology, Environmental Engineering ...other subtopics 3. APPLIED TECHNOLOGIES AND SOFTWARE ENGINEERING Software Engineering Applications, Sensors; Industrial Robots; Microrobotics; Programming; Simulations, Virtual Manufacturing; Industrial Automation; Hardware & Software; Signal Processing, Networking; Neural Network; Artificial Intelligence, Engineering Education Systems ...other subtopics 4. MECHANICAL CONSTRUCTIONS & DESIGN Design and Construction; Design Automation; Robots- Kinematics, Dynamics; Mechanism; Numerical Methods; Optimal Design, Tolerance Analysis; CAD technologies; Environmental Design, Fluid Mechanics, Mechatronics ...other subtopics IMPORTANT DATES Submission of abstracts - March 15th 2016 Submission of the full paper - May 15th 2016 Registration fee payment - June 15th 2016 Final Program - July 15th 2016 TMT 2016 - September 24th to October 1st 2016 ANNOUNCEMENT: TMT proceedings is part of EBSCO database. EBSCO database is among wide recognized online academic database that offers a large number of protected database with full text and databases to the general public in the widest range

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Mašinstvo 1(13), 23 – 40, (2016) A.Mujkanović et al.: MIX DESIGN OF SELF-COMPACTING…

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PROJEKTOVANJE SASTAVA SAMOZBIJAJUĆEG BETONA SA VISOKIM UDJELOM KALCIJSKOG ELEKTROFILTERSKOG

PEPELA ZA PREFABRIKOVANE ELEMENTE

MIX DESIGN OF SELF-COMPACTING CONCRETE CONTAINING HIGH VOLUME CALCAREOUS FLY ASH FOR PRECAST ELEMENTS

Adnan Mujkanović, Ilhan Bušatlić, Marina Jovanović, Dženana Bečirhodžić, Vahid Redžić University of Zenica, Bosnia & Herzegovina Ključne riječi: projektovanje sastava, samozbijajući beton, UCL metoda, visoki udio elektrofilterskog pepela, prefabrikovani elementi Keywords: mix design, self-compacting concrete, UCL method, high volume fly ash, precast elements Paper received: 10.02.2016. Paper accepted: 20.03.2016.

Originalni naučni rad REZIME U ovom radu proučavana je mogućnost projektovanja samozbijajućeg betona sa visokim udjelom kalcijskog elektrofilterskog pepela (W) za prefabrikovane elemente. Do sada su razvijene mnoge metode projektovanja sastava samozbijajućeg betona, a kao najpogodnija metoda u ovom istraživanju odabrana je UCL metoda projektovanja sastava samozbijajućeg betona. U prvoj fazi izvršena su preliminarna ispitivanja na malterskoj mješavini pomoću mini konusa i mini V-lijevka, nakon čega je definisan optimalan sastav mješavine. U drugoj fazi pripremljena je i ispitana mješavina samozbijajućeg betona. Na kraju, na osnovu definisane recepture izrađeni su prefabrikovani elementi i ispitana su njihova svojstva. Na osnovu provedenih ispitivanja utvrđeno je da je koristeći UCL metodu moguće u relativno jednostavnom postupku dobiti kvalitetan samozbijajući beton.

Original scientific paper

SUMMARY In this paper, the possibility of proportioning self-compacting concrete with high volume calcareous fly ash (W) for precast elements has been investigated. So far, numerous mix design methods for self-compacting concrete have been developed, so as the most appropriate method in this investigation, the UCL method was chosen. In the first phase, the preliminary tests were conducted on the mortar mixtures using mini slump cone and mini V-funnel, and thereafter the optimal mixture composition was defined. In the second phase, self-compacting concrete mixture was prepared and tested. In the end, based on the defined recipe, the precast elements were made and their properties were tested. On the basis of the examinations, it was found that it is possible to obtain high quality self-compacting concrete by using the relatively simple procedure according to the UCL method.

1. UVOD Samozbijajući beton je nova vrsta cementnog kompozita čijom se primjenom smanjuje vrijeme građenja, obim poslova, oprema na gradilištu i buka. Samozbijajući beton teče pod utjecajem vlastite težine bez pojave segregacije, te u potpunosti popunjava oplatu bez potrebe za zbijanjem upotrebom vibracijskih uređaja. Od konvencionalnog betona razlikuje se po poboljšanoj tečljivosti i otpornosti na segregaciju, lakšoj ugradnji, osiguranoj kompaktnosti strukture, visokoj čvrstoći i povećanoj trajnosti, a samim tim i povećanoj ekonomičnosti. Zahvaljujući svojim izvanrednim svojstvima, samozbijajući beton se svrstava u betone visoke kvalitete [1].

1. INTRODUCTION Self-compacting concrete is a new type of cement composite whose application reduces the construction time, workload, construction site equipment and noise. Self-compacting concrete flows under its own weight without segregation, and fills all voids without the need for compaction using vibrating devices. It differs from conventional concrete in improved flowability properties and resistance to segregation, easier placement, insured structure compactness, higher strength and increased durability and hence increased cost effectiveness. Due to its extraordinary properties, self-compacting concrete is classified as high-quality concrete [1].


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2. PROJEKTOVANJE SASTAVA SAMOZBIJAJUĆEG BETONA Projektovanje sastava betona je kombinovanje sastavnih materijala u optimalnim omjerima kako bi se dobio beton željenih svojstava u svježem i očvrslom stanju [1]. Samozbijajući beton zahtijeva kombinaciju tri ključna svojstva: sposobnosti popunjavanja, sposobnosti prolaženja, i otpornosti na segregaciju [2]. Projektovanje sastava samozbijajućeg betona počinje definisanjem potrebnih svojstava. Kod samozbijajućeg betona suštinski važno je dobiti zadovoljavajuća svojstva samozbijanja, dok se u početku manje pažnje posvećuje svojstvima očvrslog betona. Kriteriji samozbijanja upravljaju sadržajem grubog agregata, sadržajem paste, vodopraškastim omjerom, i doziranjem aditiva [3]. Za projektovanje sastava samozbijajućeg betona razvijene su brojne metode, koje su zasnovane na različitim principima. Jedna od metoda projektovanja samozbijajućeg betona je UCL metoda [1,3]. 2.1. UCL metoda UCL metoda je metoda projektovanja sastava samozbijajućeg betona i razvijena je na University College London [3]. Metoda je vrlo pogodna za one koji se prvi put susreću sa ovom vrstom betona. UCL metoda uključuje određivanje omjera komponenata mješavine za dati skup potrebnih svojstava, a nakon toga ispitivanje svojstava mješavine, i, ukoliko je potrebno, prilagođavanje i poboljšavanje sastava mješavine. Važna karakteristika prvog dijela procesa je ispitivanje konzistencije na uzorcima maltera pomoću mini konusa i mini V-lijevka. Na ovaj način se utvrđuje vodopraškasti omjer, kao i sadržaj aditiva sa kojima se postižu optimalna svojstva. Ispitivanje maltera je daleko brže i jednostavnije nego ispitivanje betona, a time se i veći broj parametara može relativno brzo istražiti. Ovo je vrlo efikasan postupak u procesu projektovanja sastava, a postoji vrlo dobra korelacija svojstava malterskih i betonskih mješavina samozbijajućeg betona [1,3]. Na slici 1. data je procedura UCL metode projektovanja sastava. 2.1.1. Specificirana svojstva betona U tabeli 1 date su preporučene vrijednosti svojstava samozbijajućeg betona za različite vrste betonskih konstrukcija.

2. MIX DESIGN FOR SELF-COMPACTING CONCRETE Proportioning of concrete is combining the constituent materials in optimum proportions in order to obtain desired concrete properties in fresh and hardened state [1]. Self-compacting concrete requires the combination of three key properties: filling ability, passing ability and segregation resistance [2]. Designing the composition of self-compacting concrete starts with defining the required properties. For self-compacting concrete it is essential to obtain the satisfactory self-compacting properties, while initially less attention is paid to the properties of hardened concrete. Self-compacting criteria govern the coarse aggregate content, the paste content, water/powder ratio and additive dosage [3]. Numerous methods for proportioning self-compacting concrete are developed, and they are based on different principles. One of those mix design methods for self-compacting concrete is UCL method [1,3]. 2.1. UCL method UCL method is mix design method for self-compacting concrete and it is developed at University College London [3]. The method is very suitable for those new to this type of concrete. UCL method involves proportioning of the mixture components for a given set of required properties, and then testing the properties of the mixture, and, if necessary, adjusting and improving the composition of the mixture. An important characteristic of the first part of the process is to examine the consistency of the mortar samples using mini cone and mini V-funnel. In this way the water/powder ratio is determined, as well as the additive dosage for achieving optimum properties. Testing mortar is much easier and more convenient than testing concrete, and thus a greater number of parameters can be readily examined. This is a very effective step in mix design process and there is a very good correlation between the mortar and concrete properties of self-compacting concrete [1,3]. Figure 1 shows the procedure of UCL mix design method. 2.1.1. Specified concrete properties Table 1 shows the recommended properties of self-compacting concrete for various applications.


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Tabela 1. Preporučena svojstva samozbijajućeg betona za različite vrste betonskih konstrukcija [3] Table 1. Recommended properties of self-compacting concrete for various applications [3]

V-lijevak/

V-funnel

Klasa/

Class

9 – 25 s VF2

5 – 9 s VF1

3 – 5 s VF1

Rasprostiranje slijeganjem (SF)/

Slump-flow 470-570 mm 540-660 mm 630-800 mm

Klasa/

Class - SF1 SF2/SF3

Zahtijevana svojstva treba uvijek da uključuju: rasprostiranje slijeganjem, viskozitet ili sposobnost prolaženja ovisno o primjeni ili oboje može biti potrebno, a takođe je neophodna adekvatna otpornost na segregaciju, iako vizuelna procjena za vrijeme ispitivanja rasprostiranja slijeganjem može biti dovoljna. 2.1.2. Podaci o materijalima Svi materijali trebaju biti u skladu sa standardima za beton. Agregati, cement i dodaci bi trebali biti lokalno dostupni materijali. Tipovi i relativni odnosi cementa i dodataka utječu na čvrstoću i druga svojstva, stoga njihov izbor treba vršiti na osnovu prethodnog znanja o materijalima, njihovom ponašanju i svojstvima, kako onim u ranoj fazi, tako i o dugoročnim svojstvima [1,3]. Sadržaj krupnog agregata (Vca) utječe na sva ključna svojstva samozbijajućeg betona. Početni sadržaj krupnog agregata zavisi od specificiranih svojstava betona. U tabeli 2 date su preporučene vrijednosti. Volumen finog agregata ( ) se računa po izrazu: = 0,45 · 100 − (1) Volumen paste ( ) se jednostavno izračuna prema izrazu: = 100 − − (2) Sastav paste, vodopraškasti omjer i sadržaj aditiva se dobiju na osnovu ispitivanja rasprostiranja i tečenja maltera.

Required properties should always include: slump-flow, viscosity or passing ability depending on the application, or both may be required, and also, adequate segregation resistance is necessary, although visual assessment during the slump-flow test may be sufficient. 2.1.2. Materials data All materials should be in accordance with the standards for concrete. Aggregates, cement and additives should be locally available materials. Types and relative proportions of cement and additives influence the strength and other properties, so their choice should be based on prior knowledge of the materials, their behavior and properties, as those in the early ages, and also the long-term properties [1,3]. The content of coarse aggregate (Vca) affects all the key properties of self-compacting concrete. The initial content of the coarse aggregate depends on the specified properties of concrete. Table 2 shows the recommended values. The volume of fine aggregate ( ) is calculated as : = 0,45 · 100 − (1) The paste volume ( ) is then simply calculated as: = 100 − − (2) The paste composition, water/ powder ratio and additive dosage are obtained on the basis of tests on mortar using spread and V-funnel.

Rampe/ Ramps

Visoki i tanki elementi/ Tall and slenderZidovi/

Walls

Podovi/ Floors


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Ciljana svojstva maltera se određuju iz dijagrama na slikama 2. i 3. na osnovu zahtijevanih svojstava betona, te procijenjenog sadržaja krupnog agregata. Malteri se ispituju sve dok se ne postigne mješavina koja zadovoljava potrebne kombinacije rasprostiranja i vremena tečenja [3].

The target mortar properties are obtained from required concrete properties and the estimated coarse aggregate content using Figures 2 and 3. Mortars are tested until a mix that meets the required combinations of spread and flow time is obtained [3].

Slika 1. Procedura UCL metode projektovanja sastava [4] Figure 1. Procedure of the UCL mix design method [4]

Specificirana svojstva betonaSpecified concrete properties

Podaci o materijalimaMaterials information

Sadržaj krupnog agregata Vca

Coarse aggregate content Vca

Sadržaj finog agregata Vfa

Fine aggregate content Vfa:Vf a (%)= 0,45 · (100-Vca)

Volumen paste Vpa /Paste volume Vpa:Vp a (%)= 100-Vca -Vf a

V/P omjer i sadržaj superplastifikatora:mini konus i V-lijevakW/P and SP dosage:

the spread and V-funnel tests

Probne betonske mješavineTrial concrete mixtures

Preporučene vrijednosti

Recommended values


27

Tabela 2. Preporučene vrijednosti sadržaja krupnog agregata za početne mješavine [1,3] Table 2. Recommended values of coarse aggregate content for initial mixes [1,3]

Specificirana svojstva/Specified properties (EFNARC) Početni volumen

grubog agregata/Initial coarse aggregate volume, Vca

(%)

Rasprostiranje slijeganjem/ Slump-flow

Viskozitet/ Viscosity V-lijevak/ V-funnel

Sposobnost prolaženja/ Passing ability

J-prsten (razlika visina)/J-ring (step-height)

59 mm 41 mm

SF1, SF2,SF3 Nije specificirano/ Not speficied

Nije specificirano/ Not speficied 38

SF1, SF2,SF3 ≤ 8 s (VF1)

Nije specificirano/ Not speficied

30 > 8 i ≤ 15(VF2) 35

> 15 s (VF2) 38 < 700 (SF1/SF2)

≤ 8 s (VF2) < 15 mm

(PA1)

Nije moguće/ No mix possible

700 – 750 (SF2)

34

> 750 (SF3) 38 < 700 (SF1/SF2)

≤ 4 s (VF1) < 15 mm

(PA2)

Nije moguće/ No mix possible

700 – 800 (SF2/SF3)

32

> 800 (SF3) 35

Slika 2. Zavisnost rasprostiranja betona od rasprostiranja maltera [3] Figure 2. Correlation between the concrete slump-flow and spread of mortar [3]


28

Slika 3. Zavisnost vremena tečenja betona od vremena tečenja maltera [3] Figure 3. Correlation between the V-funnel flow time and mini V-funnel flow time [3]

3. EKSPERIMENTALNI RAD Cilj ovog istraživanja je projektovanje sastava samozbijajućeg betona sa visokim udjelom elektrofilterskog pepela klase C za prefabrikovane elemente. Kako bi se ostvario postavljeni cilj istraživanja, formulisan je plan rada koji se sastojao od četiri faze: (1) analiza postojećih preporuka i projektovanje sastava prema odabranoj metodi; (2) laboratorijska ispitivanja i definisanje recepture za proizvodnju samozbijajućeg betona; (3) priprema betonske mješavine i ispitivanja svojstava betona u svježem stanju, te izrada laboratorijskih uzoraka i ispitivanja betona u očvrslom stanju; (4) izrada betonskih prefabrikata i ispitivanja njihovih svojstava. 3.1. Projektovanje sastava samozbijajućeg betona prema UCL metodi Nakon razmatranja postojećih preporuka za projektovanje sastava samozbijajućeg betona, kao najpogodnija metoda u ovom istraživanju, izabrana je UCL metoda projektovanja sastava. Prema UCL metodi, prvi korak u projektovanju sastava mješavine je definisanje potrebnih svojstava za specifičnu primjenu. Kako je cilj rada izrada betonskih prefabrikata, tačnije prefabrikovanih ploča i tunelskih ivičnjaka, to se na osnovu tabele 1 vidi da su, za ovu specifičnu primjenu, potrebna sljedeća svojstva: • klasa rasprostiranja SF3 (rasprostiranje

slijeganjem >750 mm) i • klasa viskoznosti VF1 (vrijeme prolaska kroz

V-lijevak 5 – 9 s).

3. EXPERIMENTAL WORK The research objective is to design high volume class C fly ash self-compacting concrete for precast elements. In order to realize the research objective, it has been formulated a plan consisted of four phases: (1) analysis of the existing recommendations and proportioning according to the selected method; (2) laboratory examinations and defining the recipe for the production of self-compacting concrete; (3) preparation of the concrete mixture and testing the concrete properties in fresh state, as well as the production of laboratory samples and testing of concrete properties in hardened state; (4) production of the precast elements and testing their properties. 3.1. Proportioning of self-compacting concrete according to the UCL method After considering the existing recommendations for proportioning self-compacting concrete, as the most appropriate mix design method in this investigation, the UCL method was selected. According to the UCL method, the first step in proportioning of the mixture is defining the required properties for the specific application. Since the research objective is to produce precast elements, more precisely prefabricated slabs and tunnel curbs, based on Table 1 it is observed that, for this specific application, the following properties are required: • slump-flow class SF3 (slump-flow >750 mm)

and • viscosity class VF1 (V-funnel 5 – 9 s).


29

Za te klase rasprostiranja i viskoznosti odgovaraju: • klasa sposobnosti prolaženja PA2 ( H2/H1 ≥

0,8) i • klasa otpornosti na segregaciju SR2 (omjer

segregacije ≤ 15 %). Prilikom projektovanja sastava mješavine prema UCL metodi prvi dio je ispitivanje na malteru, kako bi se utvrdio vodopraškasti omjer, kao i doziranje aditiva u cilju postizanja optimalnih svojstava. Sljedeći korak je određivanje volumnog procenta krupnog agregata na osnovu tabele 2, a zatim sitnog agregata i cementne paste prema jednačinama (1) i (2). Zadati maseni udio vezivne komponente, koju predstavlja smjesa cementa i elektrofilterskog pepela, je 400 kg/m3. Proračunat je sastav mješavine kod koje je cement zamijenjen elektrofilterskim pepelom, dok je, s obzirom da je sadržaj veziva fiksan, potrebni (proračunati) udio paste u mješavini betona postignut dodatkom krečnjačkog punila. 3.2. Laboratorijska ispitivanja i definisanje recepture samozbijajućeg betona Istraživanje je izvršeno na malterskoj mješavini u kojoj je cement zamijenjen sa 50 % elektrofilterskog pepela, a sastav pripremljene malterske mješavine prikazan je u tabeli 3. Nakon izvršenog proračuna, prema recepturi predstavljenoj u tabeli 3, pripremljena je malterska mješavina, dakle mješavina bez frakcija agregata 4-8 i 8-16 mm.

Those slump-flow and viscosity classes correspond to: • passing ability class PA2 ( H2/H1 ≥ 0,8) and • segregation resistance class SR2 (sieve

segregation ≤ 15 %). During the mixture proportioning according to UCL method, the first part is testing mortar in order to determine the water/powder ratio as well as the additives dosage to achieve optimal properties. The next step is to determine the volume of coarse aggregate based on Table 2, and then the volume of fine aggregate and cement paste according to equations (1) i (2). Proportion of the binder component, which is the mixture of cement and fly ash, is 400 kg/m3. The mixture composition, in which cement is replaced by fly ash, is calculated, while, with respect to the fixed binder content, the required (calculated) proportion of paste in the concrete mixture is achieved by adding the limestone filler. 3.2. Laboratory examinations and defining the recipe for self-compacting concrete The investigation was carried out on mortar mixture in which cement is replaced with 50 % of fly ash, and composition of this mortar mixture is shown in Table 3. After proportioning according to the recipe presented in Table 3, the mortar mixture was prepared, a mixture without the addition of aggregate fractions 4-8 i 8-16 mm.

Tabela 3. Proračunati sastav mješavine samozbijajućeg betona Table 3. Calculated composition of SCC mixture

Komponente/Components Sastav SCC (1 m3)

Composition of SCC (1 m3) Cement/Cement (kg) 200,00

Elektrofilterski pepeo/Fly ash (kg) 200,00

Filer/Filler (kg) 70,00

Voda/ Water (dm3) 174,95

Agregat/Aggregate 0-4 mm (kg) 942,84



SP (dm3) 4,58

VMA (dm3) 1,72


30

Na svježoj malterskoj mješavini izvršena su sljedeća ispitivanja: • rasprostiranje maltera i • vrijeme prolaska kroz mini V-lijevak. Rasprostiranje maltera (slika 4.a) predstavlja sposobnost tečenja maltera. Vrijeme prolaska kroz mini V-lijevak (slika 4.b) pokazuje brzinu tečenja maltera. U tabeli 4 predstavljeni su rezultati ispitivanja rasprostiranja maltera i vremena tečenja kroz mini V-lijevak.

Fresh mortar mixture was subjected to the following examinations: • spread of mortar and • mini V-funnel flow time. Spread of mortar (Figure 4.a) represents the flowability of mortar. Mini V-funnel flow time (Figure 4.b) shows the flow rate of mortar. Table 4 shows the results of testing spread of mortar and mini V-funnel flow time.

Slika 4. Ispitivanje maltera pomoću mini konusa (a) i mini V-lijevka (b) [7,8] Figure 4. Testing mortar with mini slump cone (a) and mini V-funnel (b) [7,8]

Tabela 4. Rezultati ispitivanja svježe malterske mješavine Table 4. Results of testing fresh mortar mixture

Ispitivanje/ Testing

Samozbijajući beton/ Self-compacting concrete

Rasprostiranje maltera (mm)/ Spread of mortar (mm) 315

Vrijeme prolaska kroz mini V-lijevak (s)/ Mini V-funnel flow time (s) 2,65

Slika 5. Zavisnost rasprostiranja betona od rasprostiranja maltera

Figure 5. The correlation between the concrete slump flow and spread of mortar

a. b.


31

Zavisnost rasprostiranja betona od rasprostiranja maltera za različite volumne udjele krupnog agregata prikazana je na slici 5. Na osnovu grafičkog prikaza ovih korelacija, utvrđeno je da je izmjereno rasprostiranje maltera u skladu sa zadatim rasprostiranjem betona.

The correlation between the concrete slump flow and spread of mortar for different coarse aggregate volumes is showed in the Figure 5. By plotting these correlations, it was found that the measured slump-flow of mortar is in accordance with the set value of concrete slump-flow.

Slika 6. Zavisnost vremena tečenja betona od vremena tečenja maltera Figure 6. The correlation between the V-funnel flow time and mini V-funnel flow time

Zavisnost vremena tečenja betona od vremena tečenja maltera za različite volumne udjele krupnog agregata prikazana je na slici 6. Na osnovu grafičkog prikaza ovih korelacija, utvrđeno je da je izmjereno vrijeme tečenja maltera u skladu sa zadatim vremenom tečenja betona.

The correlation between the V-funnel flow time and mini V-funnel flow time for different coarse aggregate volumes is showed in the Figure 6. By plotting these correlations, it was found that the measured mini V-funnel flow time is in accordance with the set value of V-funnel flow time.

3.3. Priprema i ispitivanje betonske mješavine Nakon projektovanja sastava prema UCL metodi projektovanja sastava, pripremljena je mješavina samozbijajućeg betona. Nakon ispitivanja malterske mješavine izvršene su male korekcije u sastavu betonske mješavine, dok je sastav pripremljene betonske mješavine prikazan u tabeli 5.

3.3. Preparation and testing of the concrete mixture After propotioning according to the UCL mix design method, a self-compacting concrete mixture was prepared. After testing mortar mixture some corrections in the compostions of concrete have been made, while the composition of prepared concrete mixture is shown in Table 5.

3.3.1. Komponente sastava samozbijajućeg betona Za pripremanje mješavine samozbijajućeg betona korištene su lokalno dostupne sirovine. Kao vezivna komponenta korišten je Portland-cement CEM I 52,5 N. Elektrofilterski pepeo Termoelektrane „Kakanj“ je korišten kao mineralni dodatak. Kao agregat u betonskoj mješavini, korišten je trofrakcijski drobljeni krečnjak, sa frakcijama 0-4, 4-8 i 8-16 mm.

3.3.1. Components of the self-compacting concrete For the preparation of self-compacting concrete mixture locally available raw materials were used. As binder component the Portland-cement CEM I 52,5 N was used. Fly ash from the Power plant „Kakanj“ was used as a mineral additive. As aggregate in the concrete mixture, the three-fraction crushed limestone aggregate, with fractions 0-4, 4-8 i 8-16 mm, was used.


32

U prilogu A data su najvažnija svojstva komponenti betona. Mljeveni krečnjak je korišten kao punilo. Kao hemijski aditivi korišteni su superplastifikator (SP) na bazi polikarboksilat etera i modifikator viskoziteta (VMA).

In the apendix A are shown the main characteristics of concrete constituents. Milled limestone was used as filler. As chemical admixtures the polycarboxylatether-based superplasticiser (SP) and viscosity modifying admixture (VMA) were used.

Tabela 5. Sastav betonske mješavine Table 5. Composition of the concrete mixture

Komponente/Components Sastav SCC (1 m3)

Composition of SCC (1 m3) Cement/Cement (kg) 200,00

Elektrofilterski pepeo/Fly ash (kg) 200,00

Filer/Filler (kg) 62,00

Voda/ Water (dm3) 176,18

Agregat/Aggregate: 0-4 mm (kg) 941,58



SP (dm3) 4,51

VMA (dm3) 1,69

3.3.2. Priprema betonske mješavine Priprema mješavine samozbijajućeg betona data je na slici 7.

3.3.2. Preparation of the concrete mixture Preparation on the self-compacting concrete mixture is given in the Figure 7.

Slika 7. Procedura miješanja mješavine samozbijajućeg betona

Figure 7. The mixing procedure of self-compacting concrete mixture 3.3.3. Ispitivanje svojstava svježe mješavine samozbijajućeg betona Na svježoj betonskoj mješavini izvršena su sljedeća ispitivanja: • rasprostiranje betona, • V-lijevak, • L-kutija, • otpornost na segregaciju, • J-prsten.

3.3.3. Testing the properties of fresh self-compacting concrete mixture Fresh concrete mixture was subjected to the following tests: • Slump-flow, • V-funnel, • L-box, • Segregation resistance, • J-ring.

Agregat i praškasti

materijali/Aggregate and

powder materials

2/3 vode1/3 voda + aditivi/

2/3 of water1/3 water + additives

Odstojavanje mješavine/

Resting

Ponovno miješanje/ Remixing

60 s 120 s 60 s 120 s


33

Rasprostiranje slijeganjem koristi se za procjenu sposobnosti popunjavanja samozbijajućeg betona, kao i tečenja samozbijajućeg betona [1,2,10]. Ispitivanje se vrši u skladu sa standardom BAS EN 12350-8.

The slump-flow is used to assess the filling ability of self-compacting concrete, as well as the flowability of self-compacting concrete [1,2,10]. The test is performed in accordance with the standard BAS EN 12350-8.

Vrijeme tečenja kroz V-lijevak pokazuje brzinu tečenja svježe mješavine samozbijajućeg betona, kao i sposobnost popunjavanja samozbijajućeg betona [1,2,11]. Ispitivanje se vrši u skladu sa standardom BAS EN 12350-9. L-kutija se koristi za procjenu sposobnosti prolaženja samozbijajućeg betona kroz uske otvore između armaturnih šipki i drugih prepreka bez segregacije ili blokiranja [1,2,12]. Ispitivanje se vrši u skladu sa standardom BAS EN 12350-10. Otpornost na segregaciju se koristi za procjenu otpornosti samozbijajućeg betona na segregaciju. Ispitivanje se vrši u skladu sa standardom BAS EN 12350-11 [1,2,13]. J-prsten se koristi za procjenu sposobnosti prolaženja i ponašanja samozbijajućeg betona pri blokiranju. Ispitivanje se vrši u skladu sa standardom BAS EN 12350-12 [1,2,14]. Rezultati ispitivanja svježe betonske mješavine prikazani su u tabeli 6. Na osnovu rezultata predstavljenih u tabeli 6, može se zapaziti da se izmjerene vrijednosti rasprostiranja betona dobro slažu sa očekivanim vrijednostima koje su određene grafički pomoću slike 5.

The V-funnel flow time shows the flow-rate of fresh self-compacting concrete mixture, as well as the filling ability of fresh self-compacting concrete [1,2,11]. The test is performed in accordance with the standard BAS EN 12350-9. L-box is used to assess the passing ability of self-compacting concrete to flow through tight openings between reinforcing bars and other obstructions without segregation or blocking [1,2,12]. The test is performed in accordance with the standard BAS EN 12350-10. Segregation resistance is used to assess the resistance to segregation of self-compacting concrete. The test is performed in accordance with the standard BAS EN 12350-11 [1,2,13]. J-ring is used to assess the passing ability and behaviour of self-compacting concrete at blocking. The test is performed in accordance with the standard BAS EN 12350-12 [1,2,14]. The results of testing fresh concrete mixture are shown in Table 6. Based on the results showed in Table 6, it can be observed that the measured values of the concrete slump-flow are in accordance with expected values determined by plotting correlations in Figure 5.

Tabela 6. Rezultati ispitivanja svježe betonske mješavine Table 6. Results of testing fresh concrete mixture



Rasprostiranje slijeganjem/ Slump flow

Prosječni dijametar(mm)/ Average diameter (mm)

790 800 gr

* T500 (s) 1,00

V-lijevak (s)/ V-funnel (s)

4,54 4,80gr

** L-kutija (H2/H1)/ L-box (H2/H1)

0,90

Omjer segregacije (%)/ Segregation ratio (%) 8,84

J-prsten/ J-ring

Prosječni dijametar (mm)/ Average diameter (mm) 790

T500 (s) 1,00 Razlika visina (mm)/

Step height (mm) 8

*SFgr – Rasprostiranje određeno grafičkom metodom na slici 4/ *SFgr – Slump-flow determined by plotting the correlations in Figure 4

**Vrijeme tečenja gr - Vrijeme tečenja određeno grafičkom metodom prema slici 5/ **Flow-timegr - Flow-time determined by plotting the correlations in Figure 5


34

Takođe, na osnovu rezultata predstavljenih u tabeli 6, može se zapaziti da se izmjerene vrijednosti vremena tečenja kroz V-lijevak dobro slažu sa očekivanim vrijednostima koje su određene grafički pomoću slike 6. 3.3.4. Priprema i njega laboratorijskih uzoraka samozbijajućeg betona Betonska mješavina je izlivena u kalupe i dobiveni su laboratorijski uzorci samozbijajućeg betona. Uzorci su u obliku kocki dimenzija 150x150x150 mm i prizmi dimenzija 100x100x400 mm. Nakon 24 sata, uzorci su izvađeni iz kalupa i potopljeni u vodu do starosti od 2, 14, 28, 56 i 90 dana. 3.3.5. Ispitivanje svojstava samozbijajućeg betona u očvrslom stanju Na uzorcima samozbijajućeg betona izvršena su sljedeća ispitivanja: • čvrstoća na pritisak i • brzina ultrazvučnog impulsa. Rezultati ispitivanja čvrstoće na pritisak i brzine ultrazvučnog impulsa dati su u tabelama 7 i 8, i na slikama 8 i 9.

Also, based on the results showed in Table 6, it can be observed that the measured values of the V-funnel flow-time are in accordance with expected values determined by plotting correlations in Figure 6. 3.3.4. Preparation and curing of the laboratory self-compacting concrete samples The concrete mixture was poured into moulds and laboratory samples were obtained. Samples were in form of cubes of dimensions 150x150x150 mm, and prisms of dimensions 100x100x400 mm. After 24 hours, samples were demoulded and submerged in water until the age of 2, 14, 28, 56 and 90 days. 3.3.5. Testing hardened properties of self-compacting concrete Self-compacting concrete samples were subjected to the following examinations: • compressive strength and • ultrasonic pulse velocity. The results of testing compressive strength and ultrasonic pulse velocitiy are shown in Tables 7 and 8, and in Figures 8 and 9.

Tabela 7. Rezultati ispitivanja čvrstoće na pritisak uzoraka samozbijajućeg betona Table 7. Results of testing compressive strength of self-compacting concrete samples



Čvrstoća na pritisak (MPa)/ Compressive strength (MPa)

1 dan/ 1 day

Uzorak/ Sample I 8,9 Uzorak/ Sample II 7,9 Uzorak/ Sample III 9,0

2 dana/ 2 days


14 dana/ 14 days


28 dana/ 28 days


56 dana/ 56 days


90 dana/ 90 days



35

Ispitivanje čvrstoće na pritisak uzoraka samozbijajućeg betona vrši se prema standardu BAS EN 12390-3. Ispitivanje je izvršeno na betonskim kockama dimenzija 150x150x150 mm. Ispitivana je čvrstoća na pritisak nakon 1, 2, 14, 28, 56 i 90 dana.

Testing compressive strength of self-compacting concrete samples is performed according to standard BAS EN 12390-3. The testing was performed on concrete cubes of dimensions 150x150x150 mm. The compressive strength was tested after 1, 2, 14, 28, 56 and 90 days.

Slika 8. Čvrstoća na pritisak uzoraka samozbijajućeg betona

Figure 8. Compressive strength of the self-compacting concrete samples Tabela 8. Rezultati ispitivanja brzine ultrazvučnog impulsa uzoraka samozbijajućeg betona Table 8. Results of testing ultrasonic pulse velocity of self-compacting concrete samples



Brzina ultrazvučnog impulsa (m/s) / Ultrasonic pulse velocity(m/s)

1 dan/ 1 day


2 dana/ 2 days


14 dana/ 14 days


28 dana/ 28 days


56 dana/ 56 days


90 dana/ 90 days


0

10

20

30

40

50

60

70

Čvr

stoć

a na

prit

isak

[MPa

]C

ompr

essi

ve st

reng

th [M

Pa]

Starost uzoraka [dani]Age of samples [days]

1 2 14 28 56 90


36

Ispitivanje brzine ultrazvučnog impulsa se vrši prema standardu BAS EN 12504-4. Ispitivanje je izvršeno na betonskim prizmama nakon 1, 2, 14, 28, 56 i 90 dana.

Testing ultrasonic pulse velocity is performed according to standard BAS EN 12504-4. The testing was performed on concrete prisms after 1, 2, 14, 28, 56 and 90 days.

Slika 9. Brzina ultrazvučnog impulsa uzoraka samozbijajućeg betona Figure 9. Ultrasonic pulse velocity of the self-compacting concrete samples

3.3.4. Izrada betonskih prefabrikata i ispitivanje njihovih svojstava Nakon laboratorijskih ispitivanja samozbijajućeg betona, slijedila je faza provjere kvaliteta samozbijajućeg betona sa elektrofilterskim pepelom. Stoga su u industrijskim uvjetima proizvedeni betonski elementi realnih dimenzija. Izrađene su dvije prefabrikovane ploče dimenzija 5080×2020 mm i dva tunelska ivičnjaka dimenzija 1500×300×300 mm. Nakon 28 dana, ispitana su svojstva prefabrikovanih ploča i tunelskih ivičnjaka. Ploče i ivičnjaci su ispitani sklerometrom i ultrazvučnom metodom.

3.3.4. Production of precast elements and testing their properties After laboratory testing of self-compacting concrete, the following was verifying the quality of self-compacting concrete with fly ash. Hence, the concrete elements of real dimensions were produced in industrial conditions. Two prefabricated slabs of dimensions 5080×2020 mm and two tunnel curbs of dimensions 1500×300×300 mm were produced. After 28 days, the properties of prefabricated slabs and tunnel curbs were tested. The slabs and curbs were tested by sclerometer and ultrasonic method.

Rezultati ispitivanja prefabrikata dati su u tabeli 9 i na slikama 10 i 11.

The results of testing precast elements are shown in Table 9 and in Figures 10 and 11.

Tabela 9. Rezultati ispitivanja prefabrikovanih elemenata Table 9. Results of testing precast elements



Čvrstoća na pritisak (MPa)/ Compressive strength (MPa)

Ploče/ Slabs

Uzorak/ Sample I 49,3 Uzorak/ Sample II 48,9

Ivičnjaci/ Curbs


Brzina ultrazvučnog impulsa (m/s) / Ultrasonic pulse velocity(m/s)

Ploče/ Slabs


Ivičnjaci/ Curbs


0500

100015002000250030003500400045005000

Brz

ina

ultra

zvuč

nog

impu

lsa

[m/s

]U

ltras

onic

pul

se v

eloc

itiy

[m/s

]

Starost uzoraka [dani]Age of samples [days]

1 2 14 28 56 90


37

Slika 10. Čvrstoća na pritisak ploča (lijevo)i ivičnjaka (desno) nakon 28 dana Figure 10. Compressive strength of slabs (left) and curbs (right) after 28 days

Slika 11. Brzina ultrazvučnog impulsa ploča (lijevo) i ivičnjaka (desno) nakon 28 dana Figure 11. Ultrasonic pulse velocity of slabs (left) and curbs (right) after 28 days

4. ZAKLJUČAK Na osnovu predstavljenog istraživanja može se potvrditi da je UCL metoda naročito pogodna za tehnologe i istraživače koji imaju iskustvo u radu sa konvencionalnim betonima, a prvi put se susreću sa samozbijajućim betonima. Eksperimentalnim ispitivanjima utvrđeno je da projektovani samozbijajući beton sa udjelom elektrofilterskog pepela od 50 mas. % posjeduje zadovoljavajuća svojstva: • Rasprostiranje slijeganjem: za mješavinu sa

50% elektrofilterskog pepela iznosi 790 mm. • J-prsten: rasprostiranje slijeganjem za

mješavinu sa 50 % elektrofilterskog pepela iznosi 790 mm.

• V-lijevak: vrijeme potrebno za prolazak betonske mješavine kroz V-lijevak iznosi 4,54 s za mješavinu sa 50 %elektrofilterskog pepela.

• L-kutija: razlika visina za mješavinu sa 50 % elektrofilterskog pepela iznosi H2/H1=0,9.

4. CONCLUSION Based on the presented research, it can be confirmed that the UCL method is particularly suitable for technologists and researchers who have experiences dealing with conventional concrete, but they first time encounter with self-compacting concrete. By experimental investigation it has been found that designed self-compacting concrete containing 50 w. % has satisfactory properties: • Slump-flow for mixture with 50 % of fly ash

is 790 mm. • J-ring: Slump-flow for mixture with 50 % of

fly ash is 790 mm. • V-funnel: V-funnel flow time is 4,54 s for

mixture with 50 % of fly ash. • L-box: passing ratio for mixture with 50 % of

fly ash is H2/H1=0,9. • Segregation resistance: segregation ratio for

mixture with 50 % of fly ash is 8,84 %.

0

20

40

60

Čvr

stoć

a na

prit

isak

[MPa

]C

ompr

essi

ve st

reng

th

[MPa

] I

II

0

20

40

60

Čvr

sstoća

na

priti

sak

[MPa

]C

ompr

essi

ve st

reng

th

[MPa

] I

II

0

1000

2000

3000

4000

Brz

ina

ultra

zvuč

nog

impu

lsa

[m/s

]U

ltras

onic

pul

se v

eloc

ity [m

/s]

I

II

0

1000

2000

3000

4000

5000

Brz

ina

ultra

zvuč

nog

impu

lsa

[m/s

]U

ltras

onic

pul

se v

eloc

ity [m

/s]

I

II


38

• Otpornost na segregaciju: za mješavinu sa 50 % elektrofilterskog pepela iznosi 8,84 %.

• Čvrstoća na pritisak nakon 28 dana: za laboratorijske uzorke iznosi 47,3 MPa.

• Brzina ultrazvučnog impulsa nakon 28 dana za laboratorijske uzorke iznosi 4728,1 m/s.

• Čvrstoća prefabrikovanih ploča nakon 28 dana iznosi 49,1 MPa, a tunelskih ivičnjaka 44,8 MPa.

• Brzina ultrazvučnog impulsa nakon 28 dana za prefabrikovane ploče iznosi 3695,6 m/s, a za ivičnjake 4315,3 m/s.

Dobiveni rezultati upućuju na zaključak da je moguće proizvesti kvalitetan samozbijajući beton za betonske prefabrikate u kome je 50 mas. % cementa zamijenjeno kalcijskim elektrofilterskim pepelom. .

• Compressive strength after 28 days: for laboratory samples is 47,3 MPa.

• Ultrasonic pulse velocity after 28 days for laboratory samples is 4728,1 m/s.

• Compressive strength after 28 days for prefabricated slabs is 49,1 MPa, while compressive strength for tunnel curbs is 44,8 MPa.

• Ultrasonic pulse velocity after 28 days for prefabricated slabs is 3695,6 m/s, and for tunnel curbs is 4315,3 m/s.

The experimental investigations results indicate a conclusion that is possible to produce a high quality self-compacting concrete for precast concrete elements in which 50% of cement was replaced with calcareous fly ash.

5. LITERATURA - REFERENCES [1] De Schutter, G., J. M. Bartos, P., Domone,

P., Gibbs, J.: Self-Compacting Concrete, Whittles Publishing, Dunbeath, 2008.

[2] The European Guidelines for Self-Compacting Concrete: Specification, Production and Use, EFNARC, Farnham, 2005.

[3] Domone, P.: Proportioning of Self-Compacting Concrete – The UCL method, Department of Civil, Environmental and Geomatic Engineering, University College London, London, 2009.

[4] Shi C., Wu Z., Lv K., Wu L.: A review on mixture design methods for self-compacting concrete, ELSEVIER Construction and Building Materials 84 (2015) 387-398,

[5] Ukrainczyk, V.: Beton, Alcor, Zagreb, 1994. [6] Muravljov, M.: Građevinski materijali,

Građevinska knjiga, Beograd, 1995. [7] Slump-flow test for fresh mortar,

https://www.youtube.com/ (22.2.2016) [8] V-funnel test for fresh mortar,

https://www.youtube.com/ (22.2.2016) [9] Živković, S.: Samozbijajući beton – svojstva

i tehnologija, Pregledni rad, Materijali i konstrukcije 46 (2003) 3-4, pp. 14-23.

[10]Standard BAS EN 12350-8:2011, Ispitivanje svježeg betona – Dio 8: Samougrađujući beton – Ispitivanje rasprostiranja slijeganjem.

[11]Standard BAS EN 12350-9:2011, Ispitivanje svježeg betona – Dio 9: Samougrađujući beton – Ispitivanje V-lijevkom.

[12]Standard BAS EN 12350-10:2011, Ispitivanje svježeg betona – Dio 10:

Samougrađujući beton – Ispitivanje L-posudom.

[13]Standard BAS EN 12350-11:2011, Ispitivanje svježeg betona – Dio 11: Samougrađujući beton – Ispitivanje segregacije prosijavanjem.

[14]Standard BAS EN 12350-12:2011, Ispitivanje svježeg betona – Dio 12: Samougrađujući beton – Ispitivanje J-prstenom.

[15] Nagaratnam, B. H., Faheem, A., Rahman, M. E., Mannan, M. A., Leblouba, M.: Mechanical and Durability Properties of Medium Strength Self-Compacting Concrete with High-Volume Fly Ash and Blended Aggregates, Periodica Polytechnica Civil Engineering, Research article, 59(2), pp. 155–164, 2015.

[16]Mahoutian M., Shekarchi, M.: Effect of Inert and Pozzolanic Materials on Flow and Mechanical Properties of Self-Compacting Concrete, Research Article, Hindawi Publishing Corporation Journal of Materials Volume 2015, Article ID 239717, 11 pages.

[17] Beslać, J.: Beton u novom stoljeću, GRAĐEVINAR 54 (2002) 1, pp. 15-22.

[18] Sivakumar, A., Elumalai, G., Srinivasan, V.: A conceptual approach of the mixture proportioning technique for producing self compacting concrete, Journal of Civil Engineering and Construction Technology, Vol. 2(3), pp. 65-71, March 2011.

[19] The Concrete Portal, http://www.theconcreteportal.com

(20.2.2016) [20] Self-Consolidating Concrete,

http://www.selfconsolidatingconcrete.org (22.2.2016)


39

[21] Afiniwala, S., Patel, I., Patel, N.: Effect of High Volume of Fly Ash on Rheological Properties of Self Compacting Concrete, International Journal of Emerging Technology and Advanced Engineering, ISSN 2250-2459, Vol. 3, Issue 7, 2013, Pages 559 -565.

Coresponding author: Adnan Mujkanović University of Zenica Faculty of Metallurgy and Materials Science Email: [email protected] Phone: +38732-40-18-31

PRILOG A / APENDIX A Tabela A.1. Osnovne karakteristike Portland-cementa CEM I iz Tvornice cementa Kakanj Table A.1. Properties of Portland cement CEM I (Cement plant Kakanj)

Oksid / Oxide Mas. % / Wt. %

SiO2 20,71 Al2O3 5,69 Fe2O3 3,03 CaO 63,66 MgO 1,29 Na2O 0,08 K2O 0,54 SO3 2,74

CaO (slobodni) Cao (free)

1,46

Specifična površina po Blaine-u (cm2/g)

Blaine specific surface (cm2/g)

4130

Tabela A.2. Granulometrijski sastav Portland-cementa CEM I iz Tvornice cementa Kakanj Table A.2. Particle size distribution of Portland cement CEM I (Cement plant Kakanj)

Sito [mm] Sieve [mm]

Kumulativna masa [%] Cumulative mass [%]

0,0 0

0,045 87,9

0,08 97,2

0,09 98,1

0,125 99,3

0,200 100,0

0,600 100,0

Tabela A.3. Hemijski sastav i fizičke karakteristike elektrofilterskog pepela TE Kakanj Table A.3. Chemical composition and physical characteristics of fly ash (Thermal power plant Kakanj)

Komponenta / Component Mas. %

G.Ž. / L.O.I. 0,14 SiO2 44,85 Fe2O3 8,58 Al2O3 20,20 CaO 16,83

CaO (slobodni) / CaO (free) 1,17

MgO 2,62 K2O 1,44 Na2O 0,33

Cl- 0,001 SO3 1,16

Specifična površina po Blaine-u [cm2/g]

Blaine specific surface [cm2/g]

2530 cm2/g

Gustoća [g/cm3] / Density [g/cm3] 2,65 g/cm3

Tabela A.4. Granulometrijski sastav elektrofilterskog pepela TE Kakanj Table A.4. Particle size distribution of fly ash (Thermal power plant Kakanj)

Sito [mm] Sieve [mm]

Kumulativna masa [%] Cumulative mass [%]

0,0 0 0,045 62,2 0,08 73,4 0,09 74,9

0,125 79,9 0,200 93,3 0,600 100,0


40

Tabela A.5. Granulometrijski sastav agregata Table A.5. Particle size distribution of aggregate

Sito [mm]

Sieve

[mm]

Kumulativna masa [%]

Cumulative mass [%]

0 – 4

mm

4 – 8

mm

8 – 16

mm

22,4 100 100 100 16 100 100 93,6

12,5 100 100 35,3 8 100 98,5 4,03

6,3 99.1 63,2 3.8 4 97,71 3,85 3.2 2 65,38 2.54 2.4 1 46,99 2.1 2,0

0,7 34,53 2.05 1.56 0,5 28,96 1.96 1.24

0,25 21,38 1.84 1.1 0,125 16,52 1,26 0.95 0,063 13,09 0,41 0,77

0 0,01 0,02 0,03 Tabela A.6. Gustoća i upijanje vode agregata Table A.6. Density and water absorption of agreggate

Svojstvo Property

Frakcija agregata Aggregate fraction

0 – 4 mm

4 – 8 mm

8 – 16

mm Gustoća u suhom stanju (ρrd), Mg/m3 Oven dry density (ρrd), Mg/m3

2,65 2,69 2,69

Prividna gustoća agregata (ρa ), Mg/m3 Apparent density (ρa ), Mg/m3

2,74 2,74 2,72

Gustoća u zasićenom površinski suhom stanju (ρssd), Mg/m3 Saturated surface dry density (ρssd), Mg/m3

2,68 2,70 2,70

Upijanje vode (WA24), Mg/m3 Water absorption (WA24), Mg/m3

0,23 0,21 0,21

Tabela A.7. Karakteristike superplastifikatora Dynamon PC 30 ES Table A.7. Characteristics of superplasticizer Dynamon PC 30 ES

Tipična svojstva za aditiv Dynamon PC 30 ES

Agregatno stanje / Aggregate state Tekućina / liquid

Boja / Color Smeđa / brown Gustoća / density 1,05 – 1,09 g/cm3 pH 5,5 – 7,5 Miješanje sa vodom na 20°C Mixing with water at 20°C

Potpuno / complete

(http://www.mapei-betontechnik.com/

Tabela A.8. Karakteristike modifikatora viskoziteta Stabilizer strong ES Tabela A.8. Characteristics of viscosity modify agent Stabilizer strong ES

Tipična svojstva za aditiv Stabilizer strong

Agregatno stanje / Aggregate state Tekućina / liquid

Boja / Color Bijela / white Gustoća / density 1,00 – 1,04 g/cm3 pH 10,5 – 12,5 Miješanje sa vodom na 20°C Mixing with water at 20°C

Potpuno / complete

(http://www.mapei-betontechnik.com/

ZAHVALNICA Autori zahvaljuju Ministarstvu obrazovanja i nauke FBiH na finansijskoj podršci. Rezultati istraživanja prikazani u radu dio su projekta „Primjena elektrofilterskog pepela u proizvodnji samozbijajućeg betona“. ACKNOWLEDGEMENTS Authors want to thank to The Ministry of education and Science FB&H on financial support. The results shown in the paper are part of the Project “Fly ash usage in Self compacting concrete production”.

Mašinstvo 1(13), 41 – 56, (2016) D. Vidaković, ….: THE APPLICABILITY TECHNIQUE…

41

PRIMJENJIVOST TEHNIKA ZA IZRADU VREMENSKIH PLANOVA ODRŽAVANJA TEHNIČKIH SUSTAVA

THE APPLICABILITY TECHNIQUE FOR MAKING TIME PLANS

FOR MAINTENANCE OF TEHNICAL SYSTEMS

Držislav Vidaković 1, Zorislav Kraus2, Hrvoje Glavaš2 1 Građevinski fakultet Osijek 2, Elektrotehnički fakultet Osijek 1,2 Sveučilište Josip Juraj Strossmayer Ključne riječi: održavanje, optimalizacija tehnički sustavi vremenski planovi Keywords: Maintenance, Optimization Tehnical system, Time plans Paper received: 08.03.2016. Paper accepted: 20.03.2016.

Pregledni rad REZIME Članak daje pregled tehnika izrade različitih vrsta vremenskih planova. Analizirane su njihove prednosti i nedostaci obzirom na zahtjeve za planiranje održavanja tehničkih sustava. Upućuje se na mogućnosti povećanja efikasnosti održavanja primjenom pogodne tehnike planiranja i optimalizacije rješenja (što daje bolju iskorištenost resursa). Vremensko planiranje je proces i naglašena je nužnost praćenja realizacije planova i prema potrebi njihovog ažuriranja, te stvaranje baze podataka za buduće planove.

Subject Reviews

SUMMARY The article gives an overview of techniques for making different types of time plans. Their advantages and disadvantages due to the requirements for maintenance planning of technical systems were analyzed. Reference is made to the possibility of increasing the efficiency of maintenance by applying suitable planning techniques and optimization solutions (that results with a better utilization of resources). Scheduling is the process and the necessity of monitoring the implementation of plans is stressed as well as necessity to update and create a database for future plans.

1. UVOD Održavanje, općenito, obuhvaća provedbu aktivnosti s ciljem da tehnički sustav funkcionira s dovoljno pouzdanosti. Pitanje vremena realiza-cije tih aktivnosti je izuzetno bitno za postizanje cilja, pa ih je najbolje organizirati i upravljati pomoću vremenskih (ili dinamičkih) planova. Za izradu vremenskih planova treba:

- definirati sve bitne događaje (početke i završetke aktivnosti i tzv. Millestone, tj. ključne točke) i potrebne aktivnosti;

- procijeniti trajanje pojedinih elemenata sustava (njihov prestanak rada je događaj) i trajanje održavateljskih aktivnosti s potrebnim resursima;

- definirati veze između događaja/aktivnosti (tehnološke i organizacijske) i prioritet pojedinih aktivnosti (može biti npr. prema riziku od otkaza);

1. INTRODUCTION Maintenance, in general, includes the implement-tation of activities aimed at the technical system to work with sufficient reliability. The question of the moment of the implementation of these active-ties is essential to achieve the goal, so it is best to organize and manage using the time plans (or dynamic plans). To create time plans one should:

- Define all important events (beginnings and endings of activities and so-called Millestones) and the necessary actions;

- To assess the lifespan of individual elements of the system (their failure is event) and duration of maintenance activities with the necessary resources;

- To define the relations between the events/ activities (technological and organizational) and the priority of certain activities (can be eg. according to risk of failure);


42

- rasporediti događaje i aktivnosti u budućem vremenu (u skladu sa zahtjevima koje obvezno treba ispuniti, postojećim uvjetima i postavljenim ciljevima);

- optimalizirati plansko rješenje (prema izabranim kriterijima) – izabrati najbolje između više mogućih varijanti.

Plansko održavanje je investicijsko održavanje. Ono ima preventivni karakter, jer omogućava sprječavanje kvarova i zastoja u radu do kojih bi zbog njih došlo. Vremenskim planiranjem povećava se pouzdanost obavljanja održavanja (zna se kada što treba učiniti i koje resurse za to treba osigurati), a omogućava se i postizanje bolje iskorištenosti resursa izvršitelja, pa time i nižih troškova. Suprotno od tradicionalnog pristupa održavanju, suvremene strategije zahtjevaju visok udio planskih poslova i dugoročno planiranje.

Proizvođači različitih strojeva dužni su dati upute za cjeloživotno održavanje, a kod tehničkih sustava dugog vijeka uporabe (npr. proizvodni pogoni, aerodromi ili lokomotive), zbog sagledavanja sveukupnih troškova i mogućnosti njihovog snižavanja treba napraviti cjeloživotni program održavanja s odgovarajućim vremenskim planom svih predvidivih aktivnosti.

Izboru i većoj kvaliteti vremenskih planova u našoj održavateljskoj praksi sada se još ne posvećuje puno pozornosti, niti je to predmet ocjenjivanja organizacije službi održavanja [1].

- Plan events and activities in advance (in accordance with the mandatory requirements, existing conditions and goals set);

- Optimize planning solution (according to selected criteria) – select the best among several possible variants.

Scheduled maintenance is the investment maintenance. It has a preventive character, because it allows the prevention of failures and downtime, which would occur without it. With scheduling, reliability of maintenance is increased (it is known when certain actions should be done and what resources it requires), and it enables a better use of executor resources, and thus lower costs. Contrary to the traditional approach to maintenance, contemporary strategies require a high proportion of planned activities and long-term planning.

Manufacturers are required to give maintenance instructions for a lifespan of the component. For technical systems with long lifespan (eg. manufacturing facilities, airports or locomotives) for the reason of an overview of the overall cost and the possibility of lowering it, a lifelong maintenance program with the corresponding time schedule of all foreseeable activities should be made.

To higher quality of maintenance plans in our maintenance practice is not given much attention, nor it is a subject of the evaluation in the organization of maintenance services [1].

2. SPECIFIČNOSTI VREMENSKOG PLANIRANJA ODRŽAVANJA Vremenskim planovima osim terminima aktivnosti, potrebno je definirati (detaljnost ovisi o razini plana i korisniku) i [2]:

- što treba raditi (u nekim slučajevima i zašto, tj. s kojim ciljem),

- gdje treba raditi, - kako treba raditi (kojom tehnikom i s čim).

Planiranje održavanja razlikuje se obzirom na: - redovitost (kontinuitet) i predvidljivost

radova, - veličinu i vrstu sustava koji se održava

(mogu biti veliki proizvodni pogoni, kao što su tvornice ili elektrane, pojedinačni strojevi ili manji sklopovi itd.),

- broj potrebnih aktivnosti, te količinu i trošak radova,

2. SPECIFICS OF TIME PLANNING MAINTENANCE Beside terms of activities itself, schedules necessary need to define (detail of the plan depends on level of the and the user) and the following [2]:

- What to do (in some cases and why, ie, to what end),

- Where to work, - How to work (which technique and with

what tools). Maintenance planning varies according to:

- Regularity (continuity) and predictability of actions,

- The size and type of system to be mainteined (big production facilities, such as factories and power plants or individual machine circuits, etc., or smaller),

- The number of required activities, and the amount and cost of activities,


43

- veličinu organizacije koja obavlja održavanje (uvelike ovisi o veličini sustava kojeg se održava, a može održavati više njih, kao npr. mehanizaciju na različitim gradilištima ili mreže javne rasvjete),

- vlasništvo (održavanje obavlja sam vlasnik ili ugovorno, za te poslove specijalizirane tvrtke).

Planiranje prema roku može biti dugoročno (cjeloživotni plan održavanja), a mogu se raditi i godišnji, mjesečni, tjedni i svakodnevni planovi rada. Izraženu potrebu za optimalizacijom vremenskog rasporeda resursa ima održavanje kroz duže vrijeme koje se obavlja s više radnika i sredstava, odnosno grupa radnika, pogotovo kada se obavlja na više sustava. Uz manje ukupne troškove, zahtjevi koji se javljaju za planiranje održavanja su:

- zadani termini ili rokovi obavljanja određenih aktivnosti,

- ograničeni resursi za obavljanje održavanja (stručna radna snaga, oprema, financije i dr.),

- promjenjivost prioriteta aktivnosti.

Tijekom dužeg vremena realizacije planiranih poslova održavanja moguće su česte izmjene planova (promjene vremenskog rasporeda aktivnosti, njihovog sadržaja i tehnologije, a zbog toga i resursa), ali i tada je neophodan početni plan kao osnova za određivanje odstupanja i podloga za izradu novog plana. Zato je poželjno da su planovi fleksibilni i da sadrže jasnim putem dobivene podatke (npr. na osnovu čega je predviđen planirani vremenski raspored aktivnosti i njihovo trajanje) koji pomažu kod ispitivanja uzroka nastalih smetnji (dali su razlog odstupanja od plana pogrešni ulazni podaci, npr. neodgovarajući normativi, ili se razlikuju stvarni uvjeti rada od predviđenih itd.) i analize učinaka.

Planovi trebaju biti razumljivi, pregledni, primjerene detaljnosti, a po potrebi se rade posebno za pojedine dijelove sustava. Prema vrsti, širini obuhvaćanja aktivnosti, razini detalja i ostalim podacima planovi trebaju odgovarati onima kojima su namijenjeni, što naročito dolazi do izražaja na različitim razinama stručnosti i nadležnosti. Cjelokupnim planom služi se onaj koji koordinira i nadzire sve radove, a pojedine dijelove detaljnije razrađuju oni koji su zaduženi za njihovo izvođenje (unutar poduzeća ili vanjski suradnici).

- The size of an organization that performs maintenance (largely depends on the size of the system maintained; one can maintaine more than one system, for example, machinery at various construction sites or public lighting),

- Ownership (maintenance performed by the owner himself or contract with companies specialized in these jobs).

Planning according to deadline may be long-term (life-long maintenance plan), and can be done as annual, monthly, weekly and daily working plans. Emphasized need for optimizing the scheduling of resources has maintenance throughout a long period of time, which is done by more workers and resources or groups of workers, especially when performed on multiple systems. Beside a lower total cost of maintenance, requirements that occur in planning are:

- Deadlines or terms of performing certain activities,

- Limited resources to perform maintenance (skilled labor force, equipment, finance, etc.),

- Volatility of priority activities.

Over a longer period of implementation of planned maintenance operations a frequent changes of plans may occur (change in timing of activities, their content and technology, and therefore the resources), but even then the initial plan is necessary as a basis for determining the deviation and the basis for drafting the new plan. Therefore, it is desirable that the plans are flexible and that the process of getting a resulting data is clear (eg. what is the basis for intended planned timetable and its duration). That helps in examining the causes of possible interference (whether the reason for deviation from the plan are the wrong input data, such as, inadequate norms, or the actual working conditions are different than the planned etc.) and analysis of its effects. Plans should be comprehensible, transparent, with appropriate detail and if necessary, made specifically for certain part of the system. According to the type, scope of activities, the level of detail and other data, plans should correspond to those whom they are intended. That is particularly evident at different levels of expertise and competence. Overall plan is used by one that coordinates and supervises all the activities. Certain parts of plan are elaborated in more detail by those who are responsible for implementation (within the company or external asociate).


44

Primjerice, operativni planovi sa svojim zahtjevima za brojnim tehničkim detaljima nisu pogodni za više upravljačke razine, dok financijske službe iziskuju odgovarajuće financijske planove, a odjeli za nabavu detaljne histograme ili tablice materijala (s pojašnjenjima) [3].

For example, operational plans with their requirements for a number of technical details are not suitable for higher menagement levels, while financial services require adequate financial planning and the procurement departments require detailed histograms or lists of materials (with explanations) [3].

3. VRSTE PLANOVA I TEHNIKA PLANIRANJA Za jednostavnije radove dobar izbor mogu biti samo tabelarno-brojčani planovi. Kao vremenski planovi održavanja pojedinih strojeva, uređaja i alata često se mogu vidjeti neke vrste tabelarno-brojčanih planova, kakav je primjer na slici 1. U njima aktivnosti najčešće nisu locirane u određenom vremenu, već je naznačen period ili precizirana količina rada (broj radnih sati, prijeđenih kilometara i dr.) nakon čega se moraju obaviti. Takvi planovi su sasvim zadovoljavajući za slučajeve kada proizvođač daje upute budućem vlasniku, tj. korisniku koji često ne obavlja sam veći dio održavanja, nego mu za to služi neka druga, specijalizirana tvrtka [3]. No, za izradu detaljnijeg plana za svaki konkretni slučaj vrijeme se može točno kalendarski odrediti (po datumima), a u tablici pružiti još više podataka koji će biti korisni pri realizaciji, kao što je pokazano na slici 2. Dani podaci trebaju biti prilagođeni vrsti održavanja i onome kome je plan namjenjen. Za pomoć onima koji obavljaju održavanje rade se i tzv. sheme vremenskog održavanja na kojima su simbolima označena mjesta na kojima treba provoditi aktivnosti održavanja (kao što je npr. kontrola, dolivanje i zamjena radnog fluida, podešavanje mehanizma, čišćenje i dr. [4]).

3. TYPES OF PLANS AND PLANNING TECHNIQUES Good choice for simpler tasks can only be table-numeric plans. Often, as maintenance schedules of individual machines, equipment or tools some sort of tabular-numerical plan can be seen (Figure 1). In those plans, activities are usually not pinpointed in a particular time, but period or quantity of work is specified (number of hours, mileage, etc.) and after that actions are needed. Such plans are quite satisfactory for cases where the manufacturer gives instructions to the new owner, ie. user who usually doesn’t performs most of the maintenance alone, but hires another, a specialized company [3]. However, to produce a more detailed plan for each individual case, scheadule may be layed out to determine actions (by date), and corresponding table can provide further information that will be useful in the implementation, as shown in Figure 2. Shown data must be adapted to the type of maintenance and persons aimed. To help those who perform maintenance so-called maintenance time scheme are made, where symbols mark places where maintenance activities should be performed (such as for example, control, filling and replacing the working fluid, adjusting mechanism, cleaning, etc. [4]).


45

Slika 1. Tabelarno brojčani plan održavanja Subaru vozila [5]

Figure 1. Tabular-numerical plan of Subaru vehicles maintenance [5]

1.ostvareno:

2.ostvareno:

3.ostvareno:

....... mjesec ....... mjesec ............ god.

....... mjesecRed. br.

Količina i jed.mj.

Izvrši- telj

Opis aktivnosti i mjesto izvedbe ....... mjesecResursi

1.realization:

2.realization:

3.realization:

Num. Quanti- ty

Execu-tors

Description of activities and location ....... monthResour. ....... month ....... month

............ year ....... month

Slika 2. Obrazac za tabelarno planiranje aktivnosti i praćenje njihove realizacije Figure 2. Form for tabular planing of activities and tracking the progres

Kada se planira realizacija aktivnosti na izduženim, linijskim objekatima (vodovodni i kanalizacijski sustavi i sl.) preporučljivi su ortogonalni planovi (na engleskom imaju nazive Time Versus Distance Diagrams, Linear Balance Charts, Linear Scheduling Method i dr.). Oni na jednoj osi imaju označena mjesta odvijanja radova (npr. stacionaža), a na drugoj vrijeme. Aktivnosti su pravci unutar grafikona, a njihov nagib pokazuje brzinu realizacije. Na slici 3. je primjer ortogonalnog plana obnove željezničkog kolosjeka napravljen s računalnim programom TILOS. Ovakav plan mora biti dovoljno detaljan, jer je zbog specifičnosti zahvata radove potrebno obaviti u kratkom periodu (preko vikenda ili noću) da bi ometanje voznog reda bilo minimalno, pa na ordinati ima podjelu u satima.

When planning the implementation of activities in the elongated, linear objects (water supply and sewage systems, etc.) plans named Time Versus Distance Diagrams, Linear Balance Charts, Linear Scheduling Method and others are recommended. They have on one axis designated places of work period (eg. Chainage) and time on the other. Activities are lines within the chart, and their slope indicates the rate of implementation. Figure 3 is an example of Time Versus Distance Diagram of reconstruction of railway tracks made by computer program TILOS. Such a plan should be detailed enough due to the specifics of interventions to be done in short period (over the weekend or at night) so the interferance to transportation would be minimal. Thus, the ordinate has a division in hours.


46

Slika 3. Dio ortogonalnog plana obnove željeznič. kolosijeka rađenog s TILOS-om [6]

Figure 3. Part of Time Versus Distance Diagram of reconstruction of railway tracks made by computer program TILOS [6]

U slučajevima kada se odvijanje radnih procesa može organizirati ciklično (radi bolje iskorištenosti i uigravanja radne snage) pogodna je posebna vrsta ortogonalnih planova koji se nazivaju ciklogrami (engleski: Line of Balance ili Repetitive Scheduling Model). Za njihovu primjenu sustav na kojem se obavljaju aktivnosti (npr. niz radionica, izduženi proizvodni pogoni, veliki brodovi, veći broj vagona ili letjelica istog tipa itd.) treba se podijeliti na više jednakih dijelova ili radnih etapa koje se označavaju na jednoj osi. Na drugoj osi je vrijeme podjeljeno na korake (taktove) koji predstavljaju vrijeme potrebno da se jedna aktivnost obavi na jednom dijelu/etapi. (Taktna organizacija prikazana ciklogramom može biti npr. i za neke radove redovitog održavanja, kao što je čišćenje i premazivanje velikih površina.) Idealni slučaj istoritmičnog obavljanja radova (ritmično ujednačeni svi procesi, tj. paralelni i bez prekida kao na slici 4.) u slučajevima iz prakse se teško može postići, ali treba mu se nastojati što više približiti usklađivanjem radnih grupa po veličini, odnosno po produktivnosti. I ortogonalni planovi i ciklogrami, iako su poznati više od 50 godina, kod nas se vrlo rijetko primjenjuju. Za sve jednostavnije slučajeve, koji nisu prethodno navedenih karakteristika, vjerovatno najbolji planovi su gantogrami. Gantogrami su jednostavni linijski planovi (po potrebi nadopunjeni brojčanim podacima) koji vrlo zorno prikazuju vremenski raspored aktivnosti. Zbog toga se već oko 100 godina, u različitim varijantama, jako puno koriste za različite namjene i područja, mada ne baš često za održavanje.

In cases where the processes can be arranged cyclically (for better utilization and workforce routine) special kind of previous plans also called Line of Balance or Repetitive Scheduling Model are suitable. For their application, system (eg. A series of workshops, elongated production facilities, large ships, a number of the wagons or aircrafts of the same type, etc.) should be divided in equal parts or work stages that are denoted on one axis. On the other axis, time is divided into steps (pulses) that represent the time required to perform an activity on one part/stage (Pulse organization shown on repetitive scheduling can be done for example for some of the routine maintenance work, such as cleaning and coating large surfaces). The ideal case of carrying out the activities in full synchonization (all processes are pulslx uniformed, ie. Parallel and without interruption as in Figure 4) in real aplications are difficult to accomplish, but it should be tried to get close by harmonization of size or productivity of working groups. I orthogonal plans and cyclograms, although known for over 50 years, in our country are very rarely applied. In simpler cases, without previously known characteristics, probably the best plans are the Gantt charts. Gantt charts are simple line plans (if necessary supplemented by numerical data), which very clearly show timetable. Therefore, they are used for about 100 years in various embodiments for lot of different purposes and areas, although not very often for maintenance.


47

8

1 2 3 4 5 6 7 8 9 10 11 12 13 14 Vrijemek - trajanje procesa na jednom dijelu sustava (procesa 1. na 1. dijelu)

6

ukupno trajanje kod istoritmičnih procesa T = k x (Br dijelova + Br procesa - 1)

7

Dijelovi sustava - etape

vrijeme isključivanja procesa =k x (Br procesa - 1)

vrijeme uključivanja procesa = k x (Br procesa -1)

5

1

2

3

4

8

1 2 3 4 5 6 7 8 9 10 11 12 13 14 Timek - duartion of process in one part of system (process 1. of first part)

time of shutdown process =k x (N process - 1)

time of inclusion process = k x (N process -1)

5

6

Total duration (if the processes are the same rhythm) T = k x (N part + N process - 1)

7

Parts of system/ phases

1

2

3

4

Slika 4. Ciklogram 7 radnih procesa (u tehnološkom slijedu) na izduženom postrojenju Figure 4. Repetitive Scheduling of 7 processes (in technological order) on a linear facility

Dobri su i za planiranje održavanja većih sustava, odnosno opsežnije radove s većim brojem aktivnosti, ako su slični već više puta izvođeni, što znači da se zna koje su aktivnosti kritične. Vrlo su pogodni za praćenje realizacije (bilježenje ostvarenoga – ispod linije koja prikazuje planirano), pa se za to mogu korisiti i ako je samo planiranje rađeno nekom drugom tehnikom. Na slici 5. je gantogram održavanja novih bagera jedne tvrtke koji rade prva dva mjeseca na pet gradilišta (prosječno 3 bagera na svakom gradilištu) s naznačenom radnom snagom (rukovatelj stroja “S”, mehaničar izvođača radova “M” i vanjski stručni suradnik “VS”) i tehnološkim (crno) i organizacijskim vezama (plavo). Na osnovu toga može se optimalizirati uporaba radne snage, odnosno planirati s njom izvođenje drugih zadataka u slobodnim periodima. (Zbog ograničenog prostora u ovom formatu na slici nisu upisani rezervni dijelovi, niti su prikazane sve održavateljske aktivnosti koje se odvijaju na bagerima).

Also, they are good for maintenance planning of larger systems or extensive work if a number of similar activities were repeatedly performed before, which means that it is known what are the critical activities. They are very useful for monitoring implementation (keeping records of realized - below the line that shows planned), so they can be used even planning itself was done by some other planning method. Figure 5 is a Gantt chart for a new excavator maintenance of a company working first two months on five different sites (average of 3 excavator at each site) with the designated labor (machine operator "S", a mechanic contractor "M" and external associate "VS") and technological (black) and organizational links (blue). It is, thus, possible to optimize the use of manpower, and plan performing other tasks with it in the free periods (due to limited space in this format in the figure are not enrolled spare parts, nor all te maintanence activities that occur on excavators are shown).


48

1.1 Gradiliš. 1 1 S x Nstroj -1.2 Gradiliš. 2 1 S x Nstroj -1.3 Gradiliš. 3 1 S x Nstroj -1.4 Gradiliš. 4 1 S x Nstroj -1.5 Gradiliš. 5 1 S x Nstroj -2.1 Gradiliš. 1 1 S+M+VS 1.1 FS(5)2.2 Gradiliš. 2 1 S+M+VS 1.2 FS(5), 2.12.3 Gradiliš. 3 1 S+M+VS 1.3 FS(5), 2.22.4 Gradiliš. 4 1 S+M+VS 1.4 FS(5), 2.32.5 Gradiliš. 5 1 S+M+VS 1.5 FS(5), 2.43.1 Gradiliš. 1 1 S+VS 1.1 FS(10), 2.53.2 Gradiliš. 2 1 S+VS 1.2 FS(10), 3.13.3 Gradiliš. 3 1 S+VS 1.3 FS(10), 3.23.4 Gradiliš. 4 1 S+VS 1.4 FS(10), 3.33.5 Gradiliš. 5 1 S+VS 1.5 FS(10), 3.44.1 Gradiliš. 1 1 S+M 3.1 FS(10), 3.54.2 Gradiliš. 2 1 S+M 3.2 FS(10), 4.14.3 Gradiliš. 3 1 S+M 3.3 FS(10), 4.24.4 Gradiliš. 4 1 S+M 3.4 FS(10), 4.34.5 Gradiliš. 5 1 S+M 3.5 FS(10), 4.45.1 Gradiliš. 1 1 S+M+VS 4.1 FS(5), 4.55.2 Gradiliš. 2 1 S+M+VS 4.2 FS(5), 5.15.3 Gradiliš. 3 1 S+M+VS 4.3 FS(5), 5.25.4 Gradiliš. 4 1 S+M+VS 4.4 FS(5), 5.35.5 Gradiliš. 5 1 S+M+VS 4.5 FS(5), 5.46.1 Gradiliš. 1 1 S+M+VS 5.1 FS(25), 5.56.2 Gradiliš. 2 1 S+M+VS 5.2 FS(25), 6.16.3 Gradiliš. 3 1 S+M+VS 5.3 FS(25), 6.26.4 Gradiliš. 4 1 S+M+VS 5.4 FS(25), 6.36.5 Gradiliš. 5 1 S+M+VS 5.5 FS(25), 6.4

18Red. br.

Aktivnost Mjesto izvođenja

Radna snaga

Ta (dana)

Pregled prije početka rada (ulja, filtara, predfiltra, remenja, gusjenica, vijaka, rashlađivanja)

Zamjene nakon 50h rada (ulja, filtra zraka, predfiltra), provjera i dotezanje vijaka

Servis nakon 250h rada (zamjena filtara, ulja reduktora, elemen.oduška za zrak, podmaziv., pritezanje vijaka i čišćenje filtara)

Servis nakon 500h rada (zamjena remenja na motoru, filtra zraka i filtra za gorivo, ulja u reduktoru za vožnju i motornog ulja)

Zamjene nakon 200h rada (povratnog filtra, filtra upravljačkog voda i uloška ispusnog filtra)

Prethodna aktivnost

Kontrolni test servis nakon prvih 100h rada

60Vrijeme (radni dani) - strojevi rade oko 10h/dan

42 48 5424 30 366 12

Slika 5. Gantogram s naznačenim vezama za aktivnosti održavanja bagera na pet gradilišta [3]

1.1 Site 1 1 S x Nstroj -1.2 Site 2 1 S x Nstroj -1.3 Site 3 1 S x Nstroj -1.4 Site 4 1 S x Nstroj -1.5 Site 5 1 S x Nstroj -2.1 Site 1 1 S+M+VS 1.1 FS(5)2.2 Site 2 1 S+M+VS 1.2 FS(5), 2.12.3 Site 3 1 S+M+VS 1.3 FS(5), 2.22.4 Site 4 1 S+M+VS 1.4 FS(5), 2.32.5 Site 5 1 S+M+VS 1.5 FS(5), 2.43.1 Site 1 1 S+VS 1.1 FS(10), 2.53.2 Site 2 1 S+VS 1.2 FS(10), 3.13.3 Site 3 1 S+VS 1.3 FS(10), 3.23.4 Site 4 1 S+VS 1.4 FS(10), 3.33.5 Site 5 1 S+VS 1.5 FS(10), 3.44.1 Site 1 1 S+M 3.1 FS(10), 3.54.2 Site 2 1 S+M 3.2 FS(10), 4.14.3 Site 3 1 S+M 3.3 FS(10), 4.24.4 Site 4 1 S+M 3.4 FS(10), 4.34.5 Site 5 1 S+M 3.5 FS(10), 4.45.1 Site 1 1 S+M+VS 4.1 FS(5), 4.55.2 Site 2 1 S+M+VS 4.2 FS(5), 5.15.3 Site 3 1 S+M+VS 4.3 FS(5), 5.25.4 Site 4 1 S+M+VS 4.4 FS(5), 5.35.5 Site 5 1 S+M+VS 4.5 FS(5), 5.46.1 Site 1 1 S+M+VS 5.1 FS(25), 5.56.2 Site 2 1 S+M+VS 5.2 FS(25), 6.16.3 Site 3 1 S+M+VS 5.3 FS(25), 6.26.4 Site 4 1 S+M+VS 5.4 FS(25), 6.36.5 Site 5 1 S+M+VS 5.5 FS(25), 6.4

18Num. Activity Location

execut.Labor force

Ta (days)

Previous activity

Inspection before starting work (oil, filters, pre-filter, belts, caterpillars, screws, cooling)

Substitutions after 50 h of work (oil, air filter, pre-filter), checing and tightening screws

Service after 250 h of work (substitute filters, oil in reducer, elements vent air, lubrication, tightening screwsand cleaning filters)

Service after 500 h of work (supstitute belts on the engine, air filter and fuel filter, oil in the reducer for driving and engine oil)

Substitutions after 200 h of work (return filters, filter of control line and drain the filter catridge)

Control test service after the first 100 h of work

60Time (working days) - machines working 10h/day

42 48 5424 30 366 12

Figure 5. Gantt chart with indicated connections for mainten. activ. excavator to 5 construct. sites [3]


49

Ako postoji potreba vrlo detaljne razrade u vremenu (u satima ili minutama) proračunavaju se pojedini radni procesi, pa i operacije, i zajedno s tehnološkim zastojima prikazuju unutar jednog kraćeg vremenskog intervala (radne etape ili smjene) pomoću tehnološkog normala. Svi složeniji i specifični radovi (npr. na složenim pogonima, velikim, kompliciranim remontima i sl.) iziskuju neku vrstu mrežnog planiranja, pogotovo ako su projektno orijentirani.. Mrežno planiranje je kvantitativna matematička, brojčano-grafička tehnika (metoda), a mrežni plan (dijagram, model ili mreža) je neciklični, usmjereni graf (bez zatvorenih petlji). Ova metoda primjenjuje se od kraja 50-tih godina 20. st., a prve varijante su bile Critical Path Method (CPM) i Program Evalution and Review Technique (PERT). CPM je osmišljen u Francuskoj upravo za radove održavanja i generalnog remonta u kemijskoj industriji [7]. Ima strijelne, isključivo zatvorene planove, samo s vezama kod kojih naredna aktivnost počinje nakon što prethodna završi. PERT metoda ima stohastički način određivanja trajanja aktivnosti koje su u čvorovima, a prvo je primjenjena za realizaciju vojnih projekata. Do sada je razvijeno više stotina varijanti mrežnog planiranja [7], a najveće mogućnosti pruža metoda prethodnih aktivnosti (Precedence Diagramming Method - PDM), jer ima aktivnosti u čvorovima (mogu sadržavati veći broj različitih podataka), trajanje im se primarno određuje deterministički, daje mogućnost uspostave više vrsta vremenskih veza između prethodnih i narednih aktivnosti (“kraj – početak” (FS), ”početak – početak” (SS), “kraj – kraj” (FF) s mogućnosti stavljanja vremenske odgode uz vezu, koja npr. uz prvi tip veze označava poslije koliko dana naredna aktivnost počinje nakon što prethodna završi), planovi mogu biti s više početnih i završnih čvorova, tj. aktivnosti, te je na osnovu nje razrađeno najviše modela za optimalizaciju rješenja. Slika 6 pokazuje mrežni plan izrađen PDM-om, kakvog vjerojatno ne bi imalo smisla raditi za jedan primjer s tako malo aktivnosti, ali takav može biti generalni plan s čvorovima koji predstavljaju rad na pojedinim dijelovima sustava i koji su po potrebi detaljnije razrađeni u zasebnim podmrežama.

If there is a need for very detailed elaboration of the time plan (in hours or minutes) individual work processes are calculated, including operations, and together with the technological setbacks displayed within a short time interval (working stages or shift) by means of technological normal. All more complex and specific actions (eg . complex plants, a large, complicated repairs, etc.) require some type of network planning, especially if they are project-oriented. Network planning is a quantitative mathematical, numerical - graphic technique (method ), and a network plan (diagram, model or network) is non-cyclic, directed graph (with no closed loops) . This method is applied from the end of the 50 's of the 20th century. The first versions were Critical Path Method (CPM) and Program Evalution and Review Technique (PERT). CPM is designed in France specifically for the maintenance and overhaul of the chemical industry [7]. It has pointers, strictly closed plans, with connections where the next activity begins after the previous ends. PERT method has a stochastic method of determining the duration of activities that are in knots. First applications were for the realization of military projects.So far hundreds of varieties of network planning were developed [7], and the widest opportunities provides methods of previous activity (Precedence Diagramming Method - PDM) because it has activities in knots (may contain a number of different data), the duration is primarily determined deterministicly, it enables the ability to make more kinds of time links between past and future activities ("finish – start" (FS), "start – start" (SS), "finish – finish" (FF) with the possibility of placing time delay within a link, which eg. with the first type of connection determines after how many days the next activity begins after the previous ends), plans can be with more than one start and end node, ie, activities, and it was base for the greatest number of models for solution optimization. Figure 6 shows a PDM network plan. This kind of plan probably makes no sense for an example with so little activity, but it can be a general plan with nodes that represent activity of the individual part of the system and, if necessary, are further elaborated in particular subnets.


50

2 B 4 D 10 J10 17 5 17 18 34 21 14 31 33 36

14 31 19 36 51 54

1 A 3 C 5 E 7 G 11 K 12 L 14 N 15 O9 0 12 0 12 3 12 3 5 14 16 3 10 0 5 00 0 9 9 15 18 21 24 33 46 51 54 63 63 73 739 9 21 21 27 30 33 36 38 51 67 70 73 73 78 78

6 F 8 H 13 M6 0 24 0 12 0

21 21 27 27 51 5127 27 51 51 63 63

9 I LE G E N D A B r A k t15 14 T a T F27 41 E S E F42 56 E F LF

F F (3)

S S (10)

F F (5)

S S (6) S S (6)

Figure 5. Primjer mrežnog plana (veze između čvorova na kojima ništa ne piše su normalne, tj. FS bez

vremenske zadrške) Figure 6. Example of network plan (connections between knots without any labeling are normal, ie.

FS without time delay) Metoda kritičnog lanca (Critical Chain - CC) je jedna od najnovijih varijanti mrežnog planiranja, (E. M. Goldratt, 1997. god.) koja se zbog nekih specifičnih pristupa u planiranju (veličina i raspodjela rezervi, praćenje rizika i dr. [8]) pokazala uspješnom na nizu projekata, uglavnom u SAD-u. Usporedbom različitih vrsta planiranja prema kriterijima važnim za primjenu mrežni planovi su od relevantnih stručnjaka za ovo područje ocijenjeni kao najbolji za mogućnost analize, primjenu softvera, određivanje kritičnog puta, dinamičnost i mogući broj aktivnosti i vrsta objekata. Iako su najkompliciraniji za izradu, općenito se smatraju najkompletnijom tehnikom planiranja, dok su gantogrami najjednostavniji i najuniverzalniji [9]. Prema američkim izvorima prednosti mrežnog planiranja dovode do 20 - 30 % kraćeg trajanja projekata kod kojih je ono primjenjeno, u odnosu na projekte izvođene s drugim načinima planiranja [10]. Jedino mrežnim planiranjem se točno detektira gdje je kritični put realizacije i kolike su slobodne i ukupne rezerve na aktivnostima izvan kritičnog puta, što ukazuju na mogućnost njihovog kašnjenja, a da ne dođe do vremenskog pomaka narednih aktivnosti i završetka svih radova. Stoga vremenske rezerve definiraju prioritete za realizaciju, dok u planu predočene veze između aktivnosti omogućuju bolju organizaciju i kontrolu. Također, primjena svih matematičkih metoda optimalizacije temelji se na poznavanju veličine vremenskih rezervi. Posljednja, izuzetno važna, ali i najkompleksnija faza planiranja je optimalizacija.

The method of Critical Chain (CC) is one of the latest versions of network planning, (E. M. Goldratt, 1997.), which, due to some specific approaches to planning (size and distribution of reserves, risk monitoring and other [8]) proved to be successful on a number of projects, mainly in the United States. By comparing the different types of planning according to criteria relevant to the application, network maps are assessed as the best option for analysis, software application, determining the critical path, dynamism and potential number of activities and types of facilities by relevant experts in this area. Although most complicated to produce, generally are considered the most complete technique of planning, while Gantt charts are the simplest and most universal [9]. According to American sources, the advantages of network planning lead to 20 - 30% shorter duration of projects in which it is applied, in relation to projects performed by other type of planning [10]. Only network planning accurately detects the critical path of implementation and the extent of the free and total reserves on activities outside the critical path, which indicate the possibility of delays and that there is no lag for the next activities and the completion of all sctivities. Therefore, time reserves define priorities in realization, while links between activities presented in the plan enable better organisation and control. Also, the application of all mathematical methods of optimization is based on knowledge of the size of time reserves. The last, very important, but also the most complex phase of planning is the optimization.


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Ciljevi optimalizacije nemaju uvijek iste prioritete i mogu biti suporotstavljeni, pa se događa da dok se plan po jednom parametru optimalizira po drugom se pogoršava. Optimalizacija se u pravilu radi iterativno i ne primjenjuje se uvijek ista metoda proračuna, a u nekim slučajevima je vrlo teško doći do strogog, matematičkog optimuma, te se zadovoljava s dovoljno dobrim rješenjem [3].

Vremenski planovi mogu biti izraženi u radnim danima, od prvog pa nadalje ili mogu biti locirani u neko konkretno kalendarsko vrijeme. Prebacivanje iz radnih u kalendarske dane vrlo lako se obavlja kada se koriste računalni programi za planiranje (samo se izabere između ponuđenih kalendara ili se kreira odgovarajući naznačujući koji će dani biti neradni).

S računalnim programima za vremensko planiranje (kod nas je u široj uporabi Microsoft Project) ubrzava se proračun i iscrtavanje planova, ali i dalje ostaje ovisnost o ulaznim podacima, glavna uloga planera (u procjeni trajanja aktivnosti i određivanju veza između njih da ne bi došlo do anomalija kao što je početak naredne aktivnosti prije prethodne i sl.), te problemi pojedinih tehnika u proračunu i prikazu rezultata.

The objectives of optimization do not always have the same priorities and parametars may be opposed to each other, so it happens that while the plan is optimized by one parameter, by the second parametar is getting less optimized. Optimization, as a rule, is performed iteratively and is not always applied to the same calculation method. In some cases it is very difficult to get to a strict, mathematical optimum, so sufficiently good solution is taken [3]. Time plans can be expressed in working days, from the first onwards or may be located in a specific calendar time. Switching from working days to calendar days is very easily done when using computer programs for planning (just select between calendars offered or create appropriate calendar indicating working and non-working days). The computer programs for planning (localy Microsoft Project is widely used) accelerate calculation and drawing of plans, but dependency on the input data, the main role of planners (in the assessment of the duration of the activity and determining the relationship between them to avoid anomalies such as the beginning of next activity before the previous is finished, etc.), and the problems of individual techniques with the calcultion and presentation of results still remains.

4. PROBLEMI S VREMENSKIM PLANIRANJEM U PRAKSI Uz izvjesne nedostatke metoda, problemi vremenskog planiranja uvelike su na subjektivnoj razini onih koji trebaju učestvovati u procesu izrade i provođenja planova. Nepovjerenje u vremenske planove u najvećoj mjeri je plod neznanja, isto kao i precjenjivanje i nerealna očekivanja, a zbog čega onda dolazi do početnog ushićenja i do velikih razočarenja s planovima. Pogotovo su iracionalna očekivanja da će sve biti rješeno samom nabavkom nekog od računalnih programa za planiranje, a što ustvari predstavlja tek jedan korak u pravom smjeru. Događa se da izvođači radova nabave sofisticirane programe za planiranje, a onda ih ubrzo prestanu koristiti ili se služe samo manjim dijelom njihovih mogućnosti [11]. Kao i kod svakog uvođenja nečega novoga, za planiranje je potreban određeni period uhodavanja, kada učesnici trebaju steći neka nova znanja i općenito unositi više energije u posao. U slučaju da je novi način rada potrebno artikulirati kroz više pokušaja koji ne daju odmah pozitivan rezultat, uobičajeno se javlja povećani otpor.

4. SCHEDULING PROBLEMS IN PRACTICE Apart from certain drawbacks of methods, time planning problems are largely on a subjective level of those who should participate in the process of developing and implementing plans. Mistrust in schedules for the most part is a result of ignorance, as well as overestimation and unrealistic expectations, which leeds to the initial elation and major disappointments with the plans. Especially irrational expectation is that everything will be resolved by purchaseing some computer program for planning, which is in fact only one step in the right direction. It happens that contractors purchase sophisticated planning software, and then they soon cease to use or serve only a small portion of their potential [11]. As with any introduction of something new, planning takes certain running-in period, when participants need to acquire new knowledge and generally bring more energy to the job. If the new way of doing things must articulate through a certain trial period and not immediately give a positive result, an increased resistance can be expected.


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Do suprotstavljanja planiranju nesumnjivo dolazi i iz uvriježenog nastojanja zaposlenika da se izbjegne sve što može poslužiti za kontrolu njihovog rada, dok pri tome uopće nisu svjesni koliko im dobri vremenski planovi u tom radu mogu pomoći. Neuspjeh jednih planova potiče pesimizam i sumnju u druge, buduće planove, i tako se još više narušava vjerodostojnost cijelog koncepta planiranja [3]. Upitna je veličina rezervi koje se unose u planirano trajanje aktivnosti. Tradicijski se teži većoj vjerojatnosti (65 - 90%), ali za to unešene rezerve ostaju skrivene i teško kontrolive. Često se ne zna točno kome su namijenjene i potroše se bez opravdanog razloga. Da bi ispunile svoju namjenu rezerve u planu trebaju biti plod pomne analize predstojećih situacija i temeljem toga ciljano raspoređene i transparentno naznačene. Jedno rješenje ovog problema daje metoda kritičnog lanca, kod koje se trajanje aktivnosti određuje agresivno (samo toliko da je vjerojatnost 50%), a na kraju svakog lanca aktivnosti u mreži postavlja se zaštitna vremenska rezerva (buffer) koja je uvijek znatno manja nego što je ukupno skraćenje trajanja aktivnosti u odnosu na tradicijsku procjenu s rezervama [8]. Kao po nepisanom pravilu, ako je planom slučajno predviđeno više vremena (odnosno radne snage) nego je zaista potrebno, onda će to biti zaista i utrošeno. Kod ¨prekomotnog¨ plana rukovodstvo i radnici vrlo rijetko će se potruditi da racionalizacijom i dobrom organizacijom postignu bolje rezultate, već se obično zadovoljavaju s ispunjenjem zadanog roka. Ako plan realno nije moguće ostvariti, proboji često bivaju i znatno veći nego bi zbog pogrešnog plana bilo nužno. Za sve je tada opravdanje loš plan, a analiza ostvarenih rezultata uobičajeno se izbjegava [3].

By opposing the plan undoubtedly comes from the conventional efforts of employees to avoid everything that can be used to control their work, while at the same time they are unaware of how good schedules can help them in their work. The failure of some plans encourages pessimism and doubt in others, future plans, and thus further undermining the credibility of the whole concept of planning [3]. The size of the reserves entered in the planned duration of the activities is questionable. Traditionaly pursued probability is greater (65-90%), but entered reserve remain hidden and difficult controll. Often it is not known exactly for whome reserves are intended to be spent and are usually spent without justification. To fulfill their purpose reserve in the plan should be the result of careful analysis of the upcoming situation and on this basis, targeted and transparently indicated. One solution to this problem provides a method of critical chain, in which the duration of the activity is aggressivly determined (just as much that the probability is 50%), and at the end of each chain of activities in the network a protective time reserve (buffer) is set, which is still considerably shorter than the shortening of duration of the activity in relation to the traditional estimate of the reserves [8]. As a unwrtitten rule, if the plan accidentally provided more time (or labor) than is really necessary, then this time will be actually spent. In this kind of overestimated plan, management and workers will rarely try to rationalize and with a good organization achieve better results, but are cusually satisfied with the fulfillment of the set deadline. If it is not reasonably possible to achieve the plan, breakthroughs are often much higher than would be necessary due to the wrong planinig. Then, excuse for everything is a bad plan, and analysis of achieved results are usually avoided [3].

5. PREPORUKE ZA VREMENSKO PLANIRANJE Vremenski planovi uvijek trebaju biti potpuni (sa svim radovima potrebnim za izvršenje zadatka, sa svim potrebnim informacijama) i čitljivi i razumljivi, ali ne preopširni i pretjerano precizni (smatra se da osoba na operativnoj razini može pratiti najviše 100 - 200 aktivnosti). Kod planova za duža razdoblja obično treba izraditi generalni plan koji se detaljno razrađuje po nadolazećim vremenskim odsjecima, od 1 - 3 mjeseca, za koje onda postoje pouzdanije informacije.

5. TIME PLANNING RECOMANDATIONS Time plans allways have to be complete (with all necessary information and tasks to complete), easy to read and easy to understand, but not excessivly broad and overly precise (it is considered that the person at the operational level can monitore 100 - 200 activities at most). When plans are made for longer period, it is usually necessary to draw up a general plan. General plan is then elaborated in detail for the upcoming time segments, usulally 1 - 3 months, with more reliable information in disposition.


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Ako planirani radovi nisu kratkotrajni i jednostavni, najčešće je potrebno kombiniranje više komplementarnih vrsta vremenskih planova. Na osnovu napravljenih planova realizacije aktivnosti izvode se planovi resursa – histogrami (radne snage, materijala, rezervnih dijelova itd.), te financijski planovi – dijagrami tijeka novca (cash flow) i ¨S¨ krivulja (kumulativi prikaz financijskih sredstava). Može se mrežno planirati da bi se detektirale rezerve i kritični put, a za praćenje realizacije i bilježenje ostvarenoga prema tome napraviti druge pogodne planove (npr. gantogram, liniju balansa ili liniju putokaza). Za to veliku pomoć pružaju odgovarajući računalni programi koji kada se plan napravi s nekom složenijom tehnikom (mrežnom) iz njega odmah izvode prateće tj. pomoćne planove. Pri optimalizaciji planova obvezno treba voditi računa da vremenski raspored potreba za pojedinim vrstama radne snage i sredstava rada zbog bolje iskorištenosti bude ujednačen, ako ne idealan, što je teško očekivati, barem realno ostvariv (bez učestalih i izrazitijih vršnih potreba i prekida u korištenju). Optimalizacija broja i vremenskog rasporeda resursa može se obavljati i izdvojeno, bez obzira na optimalizaciju roka i troškova [12]. Rješavanje složenih problema uvijek se jednostavnije provodi po pojedinim vremenskim ili prostornim odsjecima. Za raspodjelu resursa između aktivnosti koje se mogu odvijati istovremeno, a zahtjevaju iste resurse, može se služiti heurističkim pravilima. Ona nisu konačna i striktna, ali su dosta jednostavna za primjenu i mogu se koristiti za primjere svih veličina i složenosti [13]. Heuristička pravila su rezultat iskustva, statističke obrade, razmišljanja i logičnog zaključivanja, pa je da bi ih se uspostavilo potrebna prethodna obrada većeg broja praktičnih primjera [10]. Planiranje nije jednokratni postupak nego proces koji traje sve dok se ne završi realizacija plana. Tek ako se kontinuiranom konrolom izvedbe osigura povratni tijek informacija plan može funkcionirati kao dinamički model (slika 7). Svaki, manje ili više uspješno, realiziran posao, poželjno je iskoristiti kao određenu pripremu za naredne zadatke koje će se ponavljati na istom ili sličnim sustavima. Ne smije se oslanjati samo na osobno iskustvo pojedinaca, već treba kreirati i redovito ažurirati interne baze podataka (normative vremena i materijala), jer je pouzdanost ulaznih podataka presudna za uspješnost vremenskog i troškovnog planiranja.

If the planned activities strech over a longer period of time and are complex, combiation of several complementary types of time plans are usually needed. Based on the realization of activities planed, plans of resources are made - histograms (manpower, materials, spare parts, etc.), and financial plans - diagrams of cash flow and ¨ S¨ curve (cumulative presentation of financial assets). A network plan can be used to detect reserves and the critical path, but for tracking a realization and for monitoring implementation other appropriate plans can be used (eg, Gantt chart, line balance or line of pointers). Great help in that matter provides appropriate computer program that utilizes some complex technique (network) and immediately drafts supporting ie. auxiliary plans. During plan optimization, time table is aimed to be balanced (requirements for particular manpower and resources should be taken into accountto for better utilization of labor), if not ideal (unlikely to be achieved), but at least realistically achievable (without frequent and pronounced peak demand and interruptions). Optimization of quantity of resources and timetable can be performed separately, regardless of the deadline and costs optimization [12]. Solving complex problems is always easier carried out by individual time or spatial divisions. For the allocation of resources between the activities that can be undertaken simultaneously (and require same resources), heuristics principles may be used. They are not final and strict, but they are quite simple to implement and can be used on applications of any size and complexity [13]. Heuristic rules are the result of experience, statistical analysis, thinking and logical reasoning. Thus, it takes a large number of practical examples to be processed in order to get them established [10]. Planning is not a one-time process. It is a process that lasts until the completion of the plan implementation. Plan can function as a dynamic model only if continuous control ensures feedback (Figure 7). Each, more or less successfully job realized, is desirable to be used as a some kind of specific preparation for future tasks that will be repeated on the same or similar objects. To rely solely on the personal experience of individuals should be avoided. Regularly updated internal database should be created (norms of time and materials), because the reliability of the input data is crucial for the success of the time and cost planning.


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ažuriranja planau slučaju

Pregled i analiza postojećeg stanja

Izrada vremenskog plana održavanja

Određivanje prioriteta i redoslijeda aktivnosti (prethod. i nared. aktivnosti,

veze između njih, zadani termini)

Optimalizacija plana održavateljskih aktivnosti glede vremena i rasporeda

resursa (s ciljem minimalizacije troškova, maksimalizacije iskorištenost resursa)

Analiza raspoloživ. resursa

(prije planiranja, ako plan nije napravljen

prije uporabe)

Izrada pratećih (pomoćnih) planova

Praćenje realizacije plana održavanja i praćenje stanja održavanog sustava

Interna baza podataka

(normativi)

Analiza dokumentacije, svojstava sustava koji treba održavati (sa svim dijelovima),

propisa i uvjeta uporabe

Definiranje zadanih termina, ključnih događaja i potrebnih aktivnosti kontrole i

preventivnog održavanja

za b

uduć

e ra

dove

Slika 7. Proces dinamičkog planiranja

složenijeg i dugotrajnijeg održavanja tehničkih sustava

Internal database (norms)

Analysis of documentation, propertiesof system that should be maintained (with all parts), regulations and conditions of use

Defining the set term, key events and necessary activities for control and activities of preventive maintenance

for f

utur

e w

ork

of updating the planin the case

Review and analysis of the current

situation

Creating maintenance time plans

Prioritization and order of activities (previous and next activity, the links

between them, the default terms)

Optimization of maintenance plan with regard to time and schedule resources (with the goal of minimizing costs,

maximizing the utilization of resources)

Analysis of available resources

(before planning if the plan is not made

before use)

Making supporting (ancillary) plans

Monitoring the implement. of the mainten. plan and monitoring condition of system

Figure 7. Process of dynamic planning for

maintenance of complex system over a longer time period

Pogrešno je svu pozornost usmjeriti isključivo na izradu planova, a zanemariti ljudski faktor. Važno je pravilno uspostaviti koncept planiranja unutar sustava izvođača radova. Planiranje iziskuje timski rad i nikako ne treba biti ograničeno na specijalizirane planere, nego u izradu planova svakako trebaju biti uključeni i oni koji će voditi njihovo izvršenje. Plan mora biti prihvaćen od svih učesnika i treba poraditi na tome da svi koji učestvuju u realizaciji radova planove shvate u prvom redu kao pomoć za što uspješnije ispunjavanje zadanih ciljeva.

Focusing attention solely on the development of plans and ignoration of human factor is an error. It is important to establish the correct concept of planning within the contractor. Planning requires teamwork and should not be limited to the specialized planners, but in the development of plans should certainly be involved and those who will lead their execution. The plan must be accepted by all parties involved. It should be ensured that all involved in the project see plans primarily as an aid for successful fulfillment of the goals.

6. ZAKLJUČAK Svaki složeniji tehnički sustav treba posebno analizirati kako bi se odredio optimalni način održavanja. Kod dugotrajnog obavljanja poslova održavanja samo se vremenskim planiranjem omogućava realno sagledavanje cjeloživotnih troškova održavanog sustava (i svođenje na sadašnju vrijednost), a to je podloga za odlučivanje o isplativosti varijantnih rješenja.

6. CONCLUSION Every complex technical system should be separately analyzed to determine the optimal way of maintenance. In the long-term maintenance tasks only the scheduling allows realistic assessment of lifetime costs of system maintained (and the reduction to the present value). That is the basis for deciding on the viability of alternatives.


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Nema tehnike vremenskog planiranja i vrste plana koja bi bila najbolja za sve slučajeve, nego treba birati i kombinirati prema karakteristikama radova koji će se izvoditi, vremenu izrade plana (prije ili tijekom uporabe), ovisno dali je to cjeloživotni program ili detaljni plan i ovisno tko je krajnji korisnik plana [3]. Uz to planovi proizlaze iz raspoloživih informacija i organizacije uporabe objekta održavanja (može npr. biti sezonsko).

Kod vremenskih planova održavanja potrebna je transparentnost i mogućnost prilagođavanja novonastalim situacijama, zbog vjerojatnih promjena negativnih utjecaja na objekt održavanja, novih zahtjeva i novih mogućnosti održavanja.

Veća efikasnost obavljanja održavanja postiže se s boljim vremenskim rasporedom radnika i strojeva i zato ga na kraju planiranja treba optimalizirati. Mogućnost uštede na korištenju resursa i općenito organizaciji i provođenju rada koja se može postići s vremenskim planiranjem ovisi o vrsti održavanja, onome tko održava i onog što se održava.

Za uspjeh realizacije planiranih aktivnosti uvijek je nužan kontinuirani monitoring sa spremanjem selektiranih podataka u baze koje su važne za izradu budućih planova.

Korist koju planovi potencijalno mogu pružiti proporcionalna je trudu i znanju, odnosno troškovima uloženim u njihovu izradu. Naravno da to treba biti srazmjerno složenosti, financijskoj vrijednosti, mogućoj uštedi, rizicima, uvjetima ugovora i dr. karakteristikama svakog konkretnog slučaja.

Osim tehničkih znanja i iskustva planiranje iziskuje logiku i intuiciju, a i dozu kreativne i konceptualne sposobnosti. Planovi, kao prikaz rezultata procesa planiranja, samo su informacije na papiru, ili sve češće ekranu, i nema njihove uspješne realizacije bez odgovornog odnosa ljudi koji ih provode u djelo, odnosno nastojanja da se izvedba zaista provede planiranim putem.

There is no time planning technique or type of plan that would be best in all cases. It should be selected and combined according to the characteristics of the activities to be performed, the moment of planning (prior to or during use), depending on whether it is a lifelong program or a detailed plan and depending who the end-user of plan is [3]. In addition, plans are derived from the available information and organization of use of the facility maintened (can be eg. seasonal).

Maintenance time plans require transparency and the ability to adapt to new situations, because of the possibility of changes in negative impact to the facility maintained, new requirement and new features of maintenance.

Greater efficiency in performing maintenance is achieved with better timetable of menpower and machines, and therefore at the end of the planning it should be optimized. The potential for savings in the use of resources, general organization and implementation of activities that can be achieved with a time planning depends on the type of maintenance, subject that maintaines the facility and facility itself.

Successful implementation of planned activities rely on continuous monitoring and keeping the selected data in data bases that are important for making future plans.

The potential benefits plans can provide are proportional to the effort and knowledge, and the funds invested in their production. It should be proportionate to the complexity, financial value, possible savings, risks, contract conditions, and other characteristics of each case.

In addition to technical knowledge and experience planning requires logic and intuition, and even a dose of creative and conceptual skills. Plans, as well as graphical representation of results of planning process, are only the information on the paper, or more often on the screen. There is no successful implementation without a responsible attitude of people who put them into work and efforts to truly implement the planned route.


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7. REFERENCES [1] Vidaković, D., Lacković, Z., Bubalo, T.:

Utjecaj tehničke dijagnostike i održavanja na troškove građevinske mehanizacije, 12th International Conference on Organization, Technology and Management in Construction (SENET), Primošten, Zbornik radova na CD-u, 2015.

[2] Whiting, A.: Structural Integrity Inspection with Unmanned Aerial Vehicles, Aerecon, Perth, 2014. http://www.slideshare.net/informaoz/andrew-whiting-aurecon. Pristup 10. 02. 2016.

[3] Vidaković, D., Bubalo, T.: Metode pogodne za vremensko planiranje aktivdnosti održavanja, 21. International Conference Maintenance 2015, Šibenik, Zbornik radova: 20-30.

[4] Todosijević, M., Marić, A., Đorđević, Lj., Gligorijević, S.: Radna sposobnost mašina i njihovo održavanje, Journal of applied engineering science, br. 9: 43-47, 2005.

[5] http://www.subaruforester.org/vbulletin/f88/subaru-mauntenance-schedule-us-1060/index3.html. Pristup 10 02. 2016.

[6] TILOS – Tome-location planning softwarefor managing linear construction projects http://www.tilos.org/railway-construction.html. Accessed at 5. 02. 2016.

[7] Matejević, B.: Istorijski razvoj dinamičkog planiranja u građevinarstvu, Zbornik radova Građevinsko-arhitektonskog fakulteta u Nišu br. 27: 13–27, 2012.

[8] Francis, S.P.: Critical Chain Scheduling and Risk Management – Projecting Project Value from Uncertainty, Svjetski tjedan za upravljanje projektima, Hong Kong, 2002.

[9] Zlatanović, M., Matejević, B.: Kriterijumi kvaliteta dinamičkih planova, Zbornik radova Građevinsko-arhitektonskog fakulteta u Nišu br. 25: 255–263, 2010.

[10] Radujović, M. i suradnici: Planiranje ikontrola projekata, Građevinski fakultet Sveučilišta u Zagrebu, 2012.

[11] Vidaković, D.: Karakteristike i problemi mrežnog planiranja u građevinarstvu, M – Kvadrat br. 78: 48–56, 2015.

[12] Vidaković, D.: Optimalizacija vremenskih planova za građevinske projekte, 10. Internacionalni simpozijum iz project managementa – YUPMA, Zlatibor, Zbornik radova: 333–337, 2006.

[13] Hegazy, T., Shabeeb, K. A., elbeltagi, E., Cheema T.: Algotithm for Scheduling with Multiskilled Constrained Resources, Journal of CE and Management 126(6): 414–421, 2000.

Coresponding author: Držislav Vidaković Faculty of Civil Engineering, J. J. Strossmayer University of Osijek Email: [email protected] Phone: +385 (0)91 224 07 37

Mašinstvo 1(13), 57 – 68, (2016) J. Sredojević, ….: ENERGY POTENTIAL AND…

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ENERGETSKI POTENCIJAL I POSTUPCI TERMIČKE OBRADE OTPADNIH AUTO GUMA

ENERGY POTENTIAL AND THERMAL TREATMENT OF WASTE

TYRES

Jovan Sredojević1, Maja Krajišnik2, 1 University of Zenica, Faculty of Mechanical Engineering 2, GS-TMT d.d. Travnik Ključne riječi: otpadne auto gume, suspaljivanje, industrija cementa, piroliza Keywords: waste tyres, coincineration, cement kilns, pyrolysis Paper received: 08.09.2015. Paper accepted: xx.xx.2016.

Pregledni rad REZIME Uspostava racionalnog sistema upravljenja otpadnim auto gumama u Bosni i Hercegovini predstavljao bi značajan doprinos kako sa ekološkog aspekta zaštite osnovnih elemenata okoliša, tako i sa ekonomskog vezano za korištenje sekundarnih sirovina i energije. Otpadne gume predstavljaju vrijednu sirovinu, koje se mogu u potpunosti recikirati mehaničkim i termičkim postupcima. U Evropskoj uniji oko 80% ukupnih masa otpadnih guma se koriste u kao sekundarne energetske sirovine u industriji cementa, te za dobivanje ulja i plina u procesu pirolize. U ovom referatu dati su podaci energetskog potencijala otpadnih auto guma i osnovni parametri za njihovo korištenje kao energetskih sekundarnih sirovina.

Subject Reviews

SUMMARY Establishing rational system for waste tyre management in Bosnia and Herzegovina would represent significant contribution to environmental protection and usage of alternate energy sources. Waste tyres represent valuable raw material which can be recycled by mechanical and thermal processes. In European Union 80% of all produced waste tyres are used as secondary raw material in cement industry and pyrolysis processes. In this paper are given basic parameters of waste tyres energy potential and possibility of their usage as secondary raw materials.

1. UVOD Neadekvatno upravljanje otpadnim auto gumama predstavlja opasnost po zdravlje i sigurnost ljudi, kao i na sve elemente okoliša. Kako bi se upravljalo rizicima koje sa sobom nose otpadne auto gume, potrebno je stalno usavršavati sistem upravljanja ovim gumama. Međutim, mnoge zemlje nisu u mogućnosti da obrade i zbrinu na okolinski prihvatljiv način velike količine otpadnih auto guma. Otpadne auto gume u Evropskoj uniji su identificirane kao jedan od prioritetnih otpadnih tokova koji zahtijeva posebnu pažnju kako bi se povećala stopa njihovog iskorištavanja, a istovremeno zaštitili svi elementi okoliša. Prioriteti poboljšanja otpadnih tokova otpadnih auto guma vezani su za visoku stopu produkcije, opasnosti koje ti otpadni tokovi predstavljaju po okoliš i zdravlje ljudi, kao mogućnosti obrade i energetskog iskorištavanja otpadnih auto guma.

1. INTRODUCTION Inappropriate management of waste tyres represents hazard for human health, safety and environment. System of waste tyres management needs to be continually maintained and improved. Many countries can’t process and manage in environmental sound way enormous amounts of waste tyres generated every year. In European Union waste tyres are identified as one of priority waste line which demands special attention so that rate of their exploitation can be increased and environmental preserved. Priorities involved with waste tyres management are related to high production rates, hazards which they represent to environment and human health as well as treatment options.


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U 2010. godini Evropska unija se suočila sa izazovom adekvatnog zbrinjavanja 3,3 miliona tona otpadnih guma. Godišnji trošak zbrinjavanja otpadnih guma u Eevropskoj uniji procijenjen je na 600 miliona eura [1]. Izazov koji predstavlja organizovanje efikasnog sistema upravljanja otpadnim auto gumama veže se za tehničke i okolinske probleme koji se odnose na gume kao proizvod i kao otpad. Trenutno u Bosni i Hercegovini ne postoje tačni podaci o podukciji otpadnih auto guma. Poseban problem predstavlja nedefinsana zakonska legislativa koja uređuje oblast zbrinjavanja ovih otpadnih guma. U ovom radu dat je kratak pregled energetskog potencijala i dva postupka termičke obrade otpadnih auto guma – postupak suspaljivanja u industriji cementa koji se koristi od sedamdesetih godina u Evropskoj uniji, a postupak pirolize se od 2014. godine koristi u Bosni Hercegovini.

In 2010 European Union faced with challenge to manage in environmental sound way 3,3 million tons of waste tyres. Annual cost of waste tyres management in European Union is estimated to 600 million euro [1]. Challenge which represents organisation of efficient management system of waste tyres is related to technical and environmental issues that are related to tyres as product and as waste. We dont have accurate information about waste tyres production in Bosnia and Herzegovina. Special problem is undefined law legislative in this area. In this paper is shown short rewiev of tyrey energy potential and two thermal processes of wats etyres treatment – co-incineration in cement kilns which is used in European Union since 1970s and piroliysis which is used in Bosnia and Herzegovina since 2014.

2. ENERGETSKI POTENCIJAL I POSTUPCI OBRADE OTPADNIH AUTO GUMA Problem koji je važan kod razmatranja guma kao otpadnog materijala jeste činjenica da je brzina produkcije otpadnih guma mnogo veća nego potreba tržišta za materijalima koji nastaju mehaničkom obradom guma.

Različita tehnološka rješenja su raspoloživa za zbrinjavanje otpadnih auto guma. Postupci obrade se razlikuju ali postoji trend koji promovira materijalnu i energetsku reciklažu.

Ovaj trend se ubrzao donošenjem EU legislative o deponovanju otpada 1999/31/EC kojom je zabranjeno deponovanje cijelih otpadnih guma od 2003. godine, a od 2006. godine i deponovanje usitnjenih otpadnih auto guma. U tabeli 1 dati su postupci obrade otpadnih auto guma [2].

Parametri auto guma u dizajnu i veličini zavise o primjeni ovih guma. U tabeli 2 dat je sastav auto guma [3].

Prosječna toplotna moć otpadnih auto guma iznosi oko 32,34 MJ/kg. Za zamjenu 1 t veoma kvalitetnog uglja potrebno je oko (0,76 - 0,95) t tona auto guma. Istraživanja su pokazala da u prosjeku 18,3% ugljika u auto gumama putničkih automobila i 29,1% u kamionskim gumama dolazi iz prirodnog kaučuka.

2. CALORIC POTENTIAL AND TECHNOLOGIES FOR WASTE TYRES PROCESSING The main issue with waste tyres is that their generation rate is much higher than market need for material gained with processes of mechanical tyres treatment. Different technological solutions are available for waste tyres treatment. Treatment solutions differ but there is a trend which promotes material and energy recycling. Environmental problems and health hazards posed by waste tyres uncontrolled generation caused many countries to response with legal framework that addressed this issue. EU banned whole tire disposal in 2003 with Directive 1999/31/EC and shredded tyres disposal since 2006. In Table 1 are shown waste tyres treatment processes [2].

Parameters of tyres depend of tyre application. In table 2 is shown typical composition of tyres [3].

Average heat power of car tyres is 32,34 MJ/kg. It takes (0,76-0,95) t of car tyres to replace 1 tonne of high quality coal. Research have shown that in average 18,3% of carbon in passenger car tyres and 29,1% in truck tires comes from natural rubber.


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Tabela 1. Postupci obrade otpadnih auto guma [2] Table 1. Processes of waste tyres treatment [2]

Koncept procesa Concept of process

Tehnologija Technology

Glavni produkti - Main products Energija Energy

Ulje Oil

Čađ Char

Željezo Iron

Granulat Granulate

Puder Powder

Procesi termičke konverzije

Thermal

conversion processes

Incineracija - Incineration O O

Piroliza - O O O O Gasifikacija - O O

Plazma- + O + Suspaljivanje u

cementnim pećima Co-incineration in

cement kilns

O O +

Mehanička obrada

Mechanical treatment

Usitnjavanje Shredding O +

Usitnjavanje i granulacija

Shredding and granulation

O +

Usitnjavanje, granulacija i kriogena

obrada Shredding, granulation and criogenic treatment

O + O

O – izlaz iz procesa - O – product + - može nastati u procesu - + - can be result of process Tabela 2. Sastav auto guma [3] Table 2. Typical composition of tyres [3]

Komponenta - Component Udio – Percentage [%] Guma - Tyre 38%

Punjenje (čađ, silicij) - Fill (char, silica) 30% Ojačanje (čelik, najlon, rayon)

Reinforcement (steel, naylon, rayon) 16%

Plastifikatori (ulja i smole) Plastificators (oils i resins)

10%

Vulkanizacija (sumpor, cink oksid) Vulcanisation (sulphur, zink oxide)

4%

Antioksidanti (sprečavanje štetnog djelovanja ozona) Antioxidant (prevents ozone influence)

1%

Elementarni sastav - Elementar composition Udio – Percentage [%] Ugljik - Carbon 86,4%

Hidrogen - Hydrogen 8% Nitrogen - Nitrogen 0,5% Sumpor - Sulphur 1,7%

Kisik - Oxygen 2,4% Neposredna analiza - Analysis Udio – Percentage [%]

Isparljive komponente - Volatile components 62,1% Ugljik - Carbon 29,4% Pepeo - Ashes 7,1%

Vlaga - Moisture 1,3%


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Visok udio ugljika kao i visoka toplotna moć čine otpadne auto gume dobrim materijalom za energetsko iskorištavanje.

Postoji više različitih načina upravljanja otpadnim auto gumama koji su sigurni i efikasni, ukoliko se vrše u skladu sa zakonskim odredbama. Ove metode uključuju suspaljivanje u cilju iskorištavanja energetskog potencijala auto guma, pirolizu, mehaničku obradu itd.

Suspaljivanje otpadnih auto guma se primjenjuje kao postupak zbrinjavanja ovih guma od 70-tih godina prošlog stoljeća u mnogim zemljama Evropske unije koje imaju uređen sistem upravljanja ovom vrstom otpadnih materijala. Ovaj način zbrinjavanja guma je posebno pogodan za industriju cementa u kojima se iskorištava energetski potencijal auto guma, a metalni sastav ovih guma kao zamjena za sirovinski materijal.

Termin suspaljivanje se obično odnosi na upotrebu otpada kao zamjene za fosilna goriva u energijski intenzivnim procesima. Najvažnija uloga otpadnih auto guma u procesu suspaljivanja jeste zamjena za ugalj. Mnoge vodeće svjetske cementne kompanije (Lafarge, Holcim, Cimpor, Heidelberg, Italcement, Castle Cement) u svojim tvornicama širom svijeta primjenjuju suspaljivanje otpadnih auto guma u svojim pećima.

Otpadne auto gume se doziraju direktno u rotacionu peć u kojoj se vrši sagorijevanje na visokim temperaturama, pri čemu se vrši proizvodnja klinkera. Energetski potencijal auto guma se odmah iskoristi u vidu nastale toplote, nesagorivi ostatak se veže u cementni klinker. Prednosti ovog načina tretmana su visoke radne temperature, dugo zadržavanje otpadne guma u cementnim pećima, visok stepen miješanja, absorpcija kiselih gasova od strane alkalne sredine koja prevladava u peći.

Postupak pirolize je tehnologija koja ima značajan potencijal, iako se koristi rjeđe u odnosu na postupak suspaljivanja otpadnih auto guma. Proces pirolize odvija se u zatvorenom reaktoru bez prisustva zraka, odnosno kiseonika pri visokim temeperaturi, što dovodi do razlaganja auto guma. Postupkom pirolize nastaju pirolizni plin, pirolizna čađ, čelik i pirolizno ulje koje ima slične karakteristike kao i teška ulja. Na slici 1 date su osnovne komponente postrojenja za pirolizu starih auto guma i gumenog granulata [6].

High share of carbon and high heat power make tyres good material for energy treatment.

There are more different methods of waste tyre management which are safe and efficient if they are carried out under legal framework. These methods include co-incineration in cement kilns, pyrolysis, mechanical treatment etc.

Co-incineration of waste tyres is applied in many countries of European Union, which have regulated system of waste tyre management since 1970s. This process is especially interesting for cement industry where energy potential of tyres can be utilised and their iron share can be used as supplement for virgin materials.

Term co-incineration is usually referred to utilisation of waste tyres as replacement for fossil fuels in energy intense processed. The most important role of waste tyres in co-incineration processes is replacement for coal. Many world leading cement companies (Lafarge, Holcim, Cimpor, Heidelberg, Italcement, Castle Cement) in their factories around the world apply co-incineration of tyres in their kilns.

Wasty tyres are directly fed into rotary cement kiln. Energy potential of tyres is immediately utilised as heat, incombustible part is bound with cement clinker. Advantages of this treatment are high working temperatures, long retainment of tyre in cement kiln, high level of mixing, acid gases absorption.

Process of pyrolysis is technology which has significant potential even if it is rarely used compering to co-incineration. Pyrolysis process takes palace in closed reactor in an atmosphere devoid of oxygen in high temperatures which cause tyres to decompose. This process result with products: gas, oil, char and steel. In figure 1 are given basic components of pyrolysis plant [6].


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Slika 1. Osnovne komponente postrojenja za pirolizu starih auto guma i gumenog granulata [6]

Slika 2. Basic components of waste tyre pyrolysis plant [6]

Reaktor u kome se odvija proces pirilze

Vodeni hladnjak u kome se vrši razdvajanje tečne (pirolzno ulje) iz plinske

faze

Rezervoar teškog piroliznog ulja

Vodeni filter za prečišćavanje dimnih

plinova

Rezervoar piroliznog plina

Rezervoari piroliznog ulja

Kompezacione posude

Ventilatorsko postrojenje

Dimnjak

Ispustna cijev iz rezervoara piroliznog

plina

Kondenzaciona posuda

Gorionici za pirolizno ulje i pirolini plin

Pyrolisis process reactor

Water cooler

Reservoir for havy oil

Water filter

Gas reservoir

Oil reservoir

Compensation vessels

Fan

Chimney

Exhaust pipe

Condensation tank

Burners for oil and gas


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2.1. Suspaljivanje otpadnih auto guma u industriji cementa

Postupak dobijanja klinkera u rotacionim pećima pruža mogućnost istovremenog povrata energije i materijala iz otpadnih auto guma. Velika toplotna moć otpadnih auto guma omogućava njihovu upotrebu za zamjenu primarnih fosilnih goriva, a inertni dijelovi auto guma (prvenstveno željezo i aluminij) se koriste kao zamjena za čvrsti materijal. Ukoliko sirovinski materijal ne sadrži dovoljne količine ovih materijala, upotreba otpadnih auto guma omogućava da se na adekvatan način zadovolje potrebe za kvalitetom gotovog proizvoda. Oko 75% otpadne auto gume sastoji se od materijala na bazi ugljika što je i razlog njihove relativno visoke toplotne moći. Dodatna prednost otpadnih auto guma u poređenju sa ugljem jeste količina željeza kojeg sadrže. Željezo može djelomično zamijeniti udio željeza u sirovinskom brašnu i tako ostvariti uštedu prirodnih resursa. Otpadne auto gume imaju niži udio sumpora u odnosu na ugalj. Udio sumpora u otpadnim gumama se kreće između (1,24 – 1,3) % dok udio sumpora u uglju iznosi oko (1,1 - 2,3) %, zavisno o kvaliteti uglja. Kameni ugalj i antracit koji se najčešće upotrebljavaju u tvornicama cementa u prosjeku sadrže oko 1,5% sumpora. Najbolje raspoložive tehnologije za proizvodnju cementa nalažu da se doziranje otpadnih materijala u rotacionu peć vrši na način da se [4]:

- upotrebljavaju odgovarajuća mjesta doziranja goriva u zavisnosti od temperature i vremena zadržavanja koja zavise o dizajnu rotacione peći,

- omogući konstantno i kontinuirano doziranje otpadnih materijala u peć,

- vrši doziranje otpadnih materijala koji sadrže organske komponente, koje mogu ispariti prije zone kalcinacije, u zonu peći sa dovoljno visokom temperaturom,

- prekine suspaljivanje otpadnih materijala prilikom pokretanja i zaustavljanja procesa proizvodnje kada nije moguće ostvariti dovoljno visoke temperature i dovoljno dugo vrijeme zadržavanja.

Osobine rotacionih peći koje ih čine pogodnim za upotrebu otpadnih auto guma kao alternativnog goriva su sljedeće [4]:

- visoke temperature (temperatura plamena do 2.000°C i temperatura materijala do 1.400 °C) (slika 2),

2.1. Co-incineration of waste tyres in cement industry

Process of clinker production in cement kiln offers possibility of return of material and energy from waste tyres. High caloric potential of tyres enables they use se fossil fuel replacement and inert parts (primary iron and aluminium) are used as replacement for solid material. If virgin material doesn’t have sufficient amounts of these materials, usage of waste tyres assures that the needs for final product quality are met. About 75% of waste tyre consists of carbon based materials. Additional advantage of waste tyres, when compared to coal is amount of iron. Iron can partly replace share of iron in virgin material during clinker production and assure natural resources saving. Waste tyres have lower share of sulphur compared to coal (1,1-2,3)% depending of coal quality. Stone iron and anthracite which are commonly used in cement kilns in average consists of 1,5% of sulphur. Different types of waste materials can replace primary raw materials and/or fossil fuels in cement manufacturing and will contribute to saving natural resources. Basically, characteristics of the clinker burning process itself allow environmentally beneficial waste-to-energy and material recycling applications [4]. The essential process characteristics for the use of waste can be summarised as follows [4]:

- maximum temperatures of approx. 2000°C (main firing system, flame temperature) in rotary kilns (figure 2),

- gas retention times of about 8 seconds at temperatures above 1200°C in rotary kilns,

- material temperatures of about 1450°C in the sintering zone of the rotary kiln,

- oxidising gas atmosphere in the rotary kiln, - gas retention time in the secondary firing

system of more than 2 seconds at temperatures of above 850°C; in the precalciner, the retention times are correspondingly longer and temperatures are higher,


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- vrijeme zadržavanja plinova više od 2 sekunde na temperaturi iznad 1.200°C u rotacionoj peći (slika 2),

- kiseli plinovi koji nastaju prilikom spaljivanja neutraliziraju se alkalnom sirovinom i ostaju vezani u klinkeru,

- vrijeme zadržavanja plinova u predkalcinatoru od 2 sekunde na temperaturi iznad 850°C,

- temperatura čvrstog materijala od 850°C u predkalcinatoru,

- interakcija između sirovine i sadržaja dimnih plinova osigurava da se nesagorivi dio otpada zadržava u procesu i trajno veže za klinker,

- sorpcija gasovitih komponenti poput HF, HCl i SO2 u alkalne reaktante,

- kratko vrijeme zadržavanja izlaznih gasova na temperaturama koje vode ka stvaranju dioksina i furana,

- destrukcija organskih polutanata zbog visokih temperatura i dovoljno dugog vremena zadržavanja u peći,

- velika specifična površina materijala, intenzivna izmjena toplote i velika turbulencija dimnih plinova,

- pepeo koji nastaje prilikom sagorijevanja postaje sastavni dio klinkera, time ne nastaje novi otpad koji bi zahtijevao kasniju dodatnu obradu,

- hemijsko-minerološka inkorporacija nehlapljivih teških metala u smjesu klinkera.

Postrojenje za suspaljivanje radi na način da se sprečavaju emisije u zrak koje prouzrokuju značajno zagađivanje zraka u prizemnim slojevima, posebno da se izduvni gasovi ispuštaju na kontrolisan način u skladu sa relevantnim standardima o kvaliteti zraka.

Toplota koja se stvara procesom suspaljivanja treba biti u najvećoj mogućoj mjeri vraćena u proces.

Pored toga potrebno je kontrolisati kvalitet otpadnih auto guma, koje se koriste kao alternativno gorivo, a koje se dovoze u tvornicu. Kontrola kvaliteta se vrši uz pomoć certifikata dobavljača guma i uz pomoć internog sistema kontrole kvaliteta koji podrazumijeva [5]:

- redovna testiranja guma koje ulaze u tvornicu, kao i dodatna testiranja uzoraka,

- kontrola istovara (vizuelni + miris).

- solids temperatures of 850°C in the secondary firing system and/or the calciner,

- uniform burnout conditions for load fluctuations due to the high temperatures at sufficiently long retention times,

- destruction of organic pollutants due to the high temperatures at sufficiently long retention times,

- sorption of gaseous components like HF, HCl, SO2 on alkaline reactants

- high retention capacity for particle-bound heavy metals,

- complete utilisation of fuel ashes as clinker components and hence, simultaneous material recycling (e.g. also as a component of the raw material) and energy recovery,

- product-specific wastes are not generated due to a complete material utilisation into the clinker matrix; however, some cement plants in Europe dispose of bypass dust,

- chemical-mineralogical incorporation of non-volatile heavy metals into the clinker matrix.

The main emissions from the production of cement are emissions to air from the kiln system. These derive from the physico-chemical reactions involving the raw materials and the combustion of fuels. The main constituents of the exit gases from a cement kiln are nitrogen from the combustion air; CO2 from calcination of CaCO3 and combustion of fuel; water vapour from the combustion process and from the raw materials; and excess oxygen. The emissions ranges within which kilns operate depend largely on the nature of the raw materials; the fuels; the age and design of the plant; and also on the requirements laid down by the permitting authority. For example, the concentration of impurities and the behaviour of the limestone during firing/calcination can influence emissions, e.g. the variation of the sulphur content in the raw material plays an important role and has an effect on the range of the sulphur emissions in the exhaust gas. Beside air quality control, quality of waste tyres which are being used as fuel has to be controlled. Quality control is conducted with supplier certificate and internal system of quality control [5]:

- Regular testing of tyres, - Discharge control (visual and odor

control).


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Slika 2. Temperaturni profil u rotacionoj peći za proizvodnju klinkera [4] Figure 2. Gas and solids temperature profiles in a cyclone preheater kiln system [4]


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2.2. Piroliza otpadnih auto guma Piroliza je endotermni proces koji dovodi do termičke razgradnje materijala. Proces pirolize se odvija na temperaturama između (400 – 800) °C. Sa promjenom temperature mijenja se i distribucija produkata ili agregatno stanje u kojem se produkti nalaze. Niže temperature procesa pirolize uglavnom daju tečnije produkte, dok više temperature pogoduju nastanku plinova. Brzina odvijanja procesa i brzina prenosa toplote imaju uticaj na distribuciju produkata. Produkti pirolize starih auto guma su: pirolizna čađ (30 – 40) %, tečni ostatak – pirolizno ulje (40 – 60) % i pirolizni plinovi (5 – 20) %. Čvrsti ostatak sadrži piroliznu čađ – čisti ostatak ugljika i mineralni ostatak koji su i inicijalno sadržani u ovim gumama. Ovaj čvrsti ostatak se može koristiti kao ojačanje u industriji gume ili kao aktivni ugalj. Osnovna masa su komadići veličine (2 – 20) mm, krajevi se lome, boja crna sa sivkastim nijansama, struktura porozna. Donja toplotna moć pirolizne čađi kreće se od (29 – 34) MJ/kg [6]. Oblasti primjene pirolizne čađi su [6]:

- proizvodnja filtera (npr. aktivni ugalj), - proizvodnja gumarsko-tehničkih proizvoda, - industrija obuće, - proizvodnji pigmentnih boja, - proizvodnju tonera za štampače i kopir

aparate, - čvrstog goriva (briketa) i - sorbenta.

Tečni produkti pirolize sadrže kompleksnu mješavinu organskih komponenti (parafin, olefin i aromatske komponente). Pirolizno ulje ima visoku toplotnu moć od oko (41 – 44) MJ/kg. Dobijena ulja se mogu direktno koristiti kao gorivo, sirovina za petrohemijsku industriju a olefin ima visoku tržišnu vrijednost i koristi kao sirovina i kao izvor hemikalija [6]. Spoljni izgled piroliznog ulja:

- tamna uljna tečnost sa karakterističnim mirisom nafte,

- boja crna sa blagom smeđom nijansom. Plinoviti produkti se sastoje od nekondenzirajućih organskih komponenti kao što su H2, H2S, CO, CO2, CH4 i td. Plinovi se po pravilu, koriste kao gorivo u procesu pirolize. Donja toplotna moć se kreće oko 8 MJ/kg.

2.2 Waste tyre pyrolysis Pyrolysis is a thermochemical decomposition of organic material at elevated temperatures (400-800) °C in the absence of oxygen (or any halogen). Change of temperature involves the simultaneous change of chemical composition and physical phase. Lower process temperatures result with liquid products while higher process temperatures result with gaseous products. The distribution between solid, liquid and noncondensable gases depends on conditions of pyrolysis (temperature and time). Products of waste tyres pyrolysis are: carbon black (30-40)%, pyrolytic oil (40-60)% and gas (5-20)%. Solid products contain carbon black (pure carbon) and mineral compounds which are initially contained in tyres. This compound can be used as reinforcement in tyre industry or as active coal. Basic mass are (2-20) mm parts, black colour with shade of grey and porous structure. Lower heating value of carbon black is (29-34) MJ/kg [6]. Fields of application for these products are [6]:

- Filter production, - Shoe industry, - Solid fuel industry (briquette), - Pigment colours production, - Sorbents etc.

Liquid pyrolysis products contain complex mixture of organic components. Pyrolytic oil has high heating power (41-44) MJ/kg. Oils can be directly used as fuel, raw material for petro chemistry and olefin have high market value and can be used as raw material [6]. Tyre pyrolysis oil is chemically very complex containing aliphatic, aromatic, hetero-atom and polar fractions. The fuel characteristics of the tyre oil show that it is similar to a gas oil or light fuel oil.


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Pirolizni plin je bezbojan sa blagom nijansom bijele boje, mirisom gareži, ima sposobnost da gori u zagrijanom prostoru pri temperaturi višoj od 90 °C [6]. Na procentualni udio pojedinih faza utiču uslovi pod kojima se odvija proces: temperatura, pritisak, stepen zagrijavanja, veličine čestica, izmjene toplote u sistemu i sl. Produkti pirolize i mogućnosti njihove primjene prikazana je na slici 3 [6]. Pirolizni plin sadržava visoke koncentracije metana i etana i podsjeća na prirodni plin. U većini postrojenja pirolizni plin se koriste za zagrijavanje realktora, a ostatak se može spaljivati na baklji ili kompresovati za kasniju upotrebu. Mogućnosti primjene procesa pirolize u cilju reciklaže starih auto guma u većini slučajeva zavisi i od tržišta na koje se mogu plasirati produkti procesa. U postupku pirolize, usitnjena otpada auto guma se zagrijava na temperaturu od (400 – 800) °C u atmosferi bez kisika. Postupak pirolize je sljedeći:

- organski materijal (guma) se unosi u reaktor i podvrgava se termičkoj razgradnji pri čemu nastaju isparljive komponente i čvrsti ostatak,

- isparljive komponente se hlade i nastaju dvije vrste faza: tečna faza i nekondenzirajuća plinovita faza,

- tečna faza iznosi oko 35% početne mase gume, ova faza se zove pirolizno ulje i sastoji se od organskih komponenti C5-C20,

- nekondenzirjuća plinovita faza iznosi oko 20% početne mase i sadrži hidrogen, hidrogensulfid i lake ugljikovodike (C1-C6), i može se koristiti kao gorivo u procesu pirolize,

- čvrsti ostatak je mješavina čelika i čađi i čini oko 45% početne mase gume

Pyrolytic gas is colorless, burns in temperatures higher than 90 °C [6]. The biggest impact on pyrolysis process have: temperature, pressure, heating rate, particle size, heat exchange etc. Pyrolysis products and their application is shown in figure 3 [6]. Pyrolytic gas contain high concentracions of methane and ethane and is similar to natural gas. In most of pyrolysis plants, gas is used for reactor heating and excess concenrations can be burned on flare or compress for later application. Possibility of pyrolysis process application for waste tyres recycling depends on available product markets. In pyrolysis process, shredded waste tyre is being heated on temperature of (400-800) °C in absence of oxygen. Pyrolysis porcess can be described as follows:

- Organic material is fed into the reactor and being thermally decomposed. This process results in formation of volatile components and solid remain,

- Volatile components are being cooled and two phases are fomted: liquid phase and noncondensible gasous phase,

- Liquid phase is 35% of tyre mass, this phase is called pyrolisi oil and contain organic compounds C5-C20,

- Noncondensating gaseous phase is 20% of tyre mass and contain H2, H2S and C1-C6 and can be used as fuel in pyrolysis process,

- Solid remain is mixture of steel, char and represent about 45% of tyre mass.


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Slika 3. Produkti pirolize i mogućnosti njihove primjene [6]

Figure 3. Pyrolysis process product and their appliacation [6]


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3. ZAKLJUČAK Danas se u Evropskoj uniji zbrinjava preko 3,5 milona tona otpadnih auto na okolinski prihvatljiv način sa tendencijom daljeg povećanja. Najveće količine ovih guma se zbrinjavaju u Evropskoj uniji suspaljivanjem u industriji cementa i predstavlja vodeći termički postupak njihove obrade. Korištenje energetskog potencijala ovih guma vrši se u industriji cementa kao goriva u procesu suspaljivanja sa osnovnim fosilnim gorivom i u procesu pirolize pri čemu se dobiva veoma kvalitetno pirolizno ulje, pirolizni plin, pirolini čađ i menalni ostatak. U posljednje vrijeme i u Bosni i Hercegovini čine se početni koraci za korištenje energetskog ponetcijala starih auto guma i to njihovim korištenjem u industriji cementa i procesom pirolize. Na ovaj način, posebno industrija cementa u Bosni i Hercegovini, daje značajan doprinos za zbrijavanje ovih guma na okolinsko prihvatljiv način i ispunjavanju uslova koji su propisani Direktivama Evropske unije. Glavna barijera za razvoj procesa pirolize starih auto guma je obezbjeđenje tržišta za plasman pirolizne čađi. Pirolizna čađ sadrži fine čestice ugljika, pepela i drugih anorganskih materijala poput cink oksida, karbonata i silikata. Njegova primjena kao sirovinskog materijala je prilično ograničena jer sadrži oko 10% nečistoća. Uprkos ograničenom komercijalnom uspjehu sistema pirolize otpadnih guma, nastavljaju se radovi na razvojnim projektima ove tehnologije u mnogim zemljama svijeta. Uspjeh procesa pirolize zavisi o mogućnosti pronalaska dodatne upotrebne vrijednosti produkata pirolize, posebno piroliznog ulja i pirolizne čađi.

3. CONCLUSION In European Union 3,5 million tonnes of waste tyres are being processed every year in envirnomental sound manner. The biggest amounts of these tyres are processed by co-incineration in cement industry. Energy potential of waste tyres is being used in cement industry as fuel replacement and in pyrolysis process. Lately in Bosnia and Herzegovina first steps were made towards utilisation of wast tyres in cement kilns and in pyrolysis porcesses. Cement industry made significant contribution to waste tyres utilisation in envirnomentally sound manner. Main barrier for pyrolysis process development is providing markets for placement of carcoal. The process economy depends strongly on its commercial value. Carcoal contains fine carbon particles, ashes and other inorganic materials like zinkokside, carbonate and silicate. Its application as raw material is limited because it contains 10% of impurities. Despite limited comercial sucess of waste tyres pyrolysis systems, research on process development continue in many conutries around the world. Sucess of pyrolisis process depends on finding additional opportunities for product application, especially for pyrolytic oil and char.

7. REFERENCES [1] G.Ramos F.J. Alguacil, F.A. Lopez The

recycling of end/of/life tyres. Technological review, Revista de Metalurgia, mayo/juno, 273-284, 2011.

[2] Eddie N., Laboy/Nieves, Energy Recovery from Scrap Tyres: A Sustainable Option for Small Islands like Puerto Rico, Sustainability ISSN 2071 - 1051.

[3] E. Muzenda, A Comparative Review of Waste Tyre Pyrolisis, Gasification and Liquefaction Processes, Int Conf on Chemical Engineering and Advanced Computational Technologies, Nov 24-25, 2014.

[4] Best Available Techniques for the Cement Industry, Cembureau, 1999.

[5] M.Krajisnik, Otpadne gume kao alternativno gorivo u proizvodnji cementa, diplomski rad, Univerzitet u Zenici, Mašinski fakultet u Zenici, juni 2010.

[6] J.Sredojevic, M.Krajišnik, Reciklaža starih auto guma procesom pirolize, COMETa 2014 2nd International Scientific Conference, 2-5 december 2014., Jahorina BIH

[7] J.Sredojević, Reciklaža otpada, Mašinski fakultet u Zenici, Zenica, 2006.

Coresponding author: Sredojević Jovan Faculty of Mechanical Engineering, Univeristy of Zenica Email: [email protected] Phone: +387 (0)32 449 123

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Table 1. Table titles (Style: Times New Roman, 11pt, Normal)

Engineering stress σe / MPa

Engineeringplastic strain εe,pl / %

True stress σt / MPa

True plastic strain εt,pl / %

250,0 0,00 250,8 0,00 250,0 0,21 250,8 0,21 285,7 1,35 290,0 1,34 322,7 2,13 330,1 2,10 358,4 3,06 370,0 3,00 393,1 4,35 411,0 4,24 423,6 6,05 450,1 5,85 449,7 8,76 490,1 8,36 457,0 15,79 530,1 14,59 467,9 21,58 570,0 19,45 475,0 29,77 617,5 25,94

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XX. REFERENCES (Style: Times New Roman, 11pt, Normal) [1] P.E. Nikravesh, Computer-Aided Analysis

of Mechanical Systems, Prantice Hall Inc.,Englewood Cliff,NJ,1988.

[2] Gordon Robertson, Graham Caldwell, Joseph Hamill, Gary Kamen, Saunders Whittlesey: Research Methods in Biomechanics, Human Kinetics; 2nd edition, 2014.

[3] Imai, M.: KAIZEN: the key to Japan’s competitive success, Editorial CECSA, Mexico. In Spanish, 1996.

[4] Nemoto, M.: Total quality control for management. Strategies and techniques from Toyota and Toyoda Gosei, Prentice-Hall, Englewood Cliffs, NJ, 1987.

[5] Cheser, R.: The effect of Japanese KAIZEN on employee motivation in US manufacturing, Int J Org Anal 6(3):197–217, 1998.

[6] Aoki, K.: Transferring Japanese KAIZEN activities to overseas plants in China, Int J Oper Prod Manag 28(6):518–539, 2008.

[7] Tanner, C.; Roncarti, J.: KAIZEN leads to breakthroughs in responsiveness and the Shingo prize at Critikon, Natl Prod Rev 13(4):517–531, 1994.

[8] Rink, J.: Lean can save American manufacturing. Reliable plant. http://www.reliableplant.com/Read/330/lean-manufacturing-save. Accessed at 14 April 2014.

[9] SolidWorks, http://www.solidworks.com (12.5.2015)

Coresponding author: Name and surname Institution Email: [email protected] Phone: +xxx xx xxxxxx (Style: Times New Roman, 11pt, Bold)

CONFERENCE DATE AND VENUEThe conference will be held from 02 to 04 2016 in

Zenica, B HZenica is a town in the Zenica-Doboj Canton, in the central part ofBosnia and Herzegovina. Area of the city is 500 km ², population isabout 130 thousand. Economic center of the geographic region ofcentral Bosnia and near Travnik and Jajce, the most important cityin that part of the state.

nd th June HotelZenica, osnia and erzegovina.

INVITATION TO THE AUTHORS ANDPARTICIPANTS

CONFERENCE TOPICS

CONFERENCE OBJECTIVES

Organizing Committee would like to invite all potential authorsand participants to submmit abstracts (up to 100 words), not laterthan 20 6. The official Conference languages areEnglish, Bosnian, Serbian and Croatian.On line registration on www. .unze.ba

Conference objectives are:- Gathering of people engaged in maintenance funds for theoperation of various aspects and their structural organization,- Communication of the results of research in the field ofmaintenance, as theoretical and practical,- Exchange of experiences from practical maintenanceactivities,- Transfer of knowledge in the field of maintenance.

The will be performed as follows: plenary session(Ke papers concerned global topics), symposium (papersaccording to the conference topics) and workshops, whenneeded. We would like to inform all the potential authors toprepare papers in the following topics:

February 15 1

odrzavanje

Conferencey

st

1. Technology maintenance..... anagement...

10. Human resources in maintaining1.2. F3. O4. R5. M6. I7.

18. Safety at work19. Performance indicators of maintenance

2 Reliability and maintenance3 Logistics in the maintenance4 Quality and maintenance5 Monitoring and Diagnostics6 M and maintenance7 Information systems maintenance8 New technologies in the maintenance9 Education Maintenance

1 Asset management1 acility Management1 utsourcing1 isk Management1 Ecology and aintenance1 nventory Management1 Cost of maintenance

CONFERENCE FEEThe conference fee for authors and participants is 150,00 EUR(including members of the Scientific Committee, and sessionchairmen). The conference fee include: conference proceedings andaccompanying materials, admission to all sessions and presentations,refreshments, and welcome drink.

ACCOMPANYING EVENTSWe hereby inform interested companies and manufacturers ofequipment and devices for maintenance to be able to rent exhibitspace or to make a presentation of the company or equipment withinthe planned sessions.

IMPORTANT DATES

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Submission of abstracts ......................... ....... 20 6.Notification of acceptance of theabstracts and instructions forpreparing the papers . ............................ ......... 20 6.

Submission of the full paper ..................................... 20 6.

Registration fee payment...........................................May 20 6.

Final Programme ............................. ..................May 20 6.

....................................June 02 to 04 20 6.

.... February 15 1

.. . February 28 1

April 25 1

15 1

... ... 20 1

MAINTENANCE 2016 1

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WELCOME

TO

ZENICA

Sve informacije u vezi Skupa možete dobiti na:

telefone : +387 32 449-143, 449-145,fax:+387 32 246-612

E-mail: [email protected];s jasar @

/phone

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You can also contact:

02 - 04 June 2016, Zenica,Bosnia and Herzegovina

ODRŽAVANJE 2016MAINTENANCE 2016

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STUDIO RUMZ

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UDRUŽENJEDRUŠTVO ODRŽAVALACAU BOSNI I HERCEGOVINI

UNIVERSITY OF ZENICA(Bosnia and Herzegovina)

FACULTY OF MECHANICALENGINEERING

DRUŠTVO ODRŽAVALACAU BOSNI I HERCEGOVINIASSOCIATION „SOCIETYOF MAINTAINERS INBOSNIA AND HERZEGOVINA“

Rekonstrukcija elektrofiltera bloka 7, 230 MW

Zamjena čelične konstrukcije obrtača vagona br. 2 TE Tuzla

Revitalizacija krana MIAG 1 i transportne linije uglja

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