gerador diesel artigo traduzir

7/28/2019 Gerador Diesel Artigo Traduzir

1/5

Conversion of Stand by G enerator Facilities toCombined Heat and Power Units"Technical Aspests"AhmadZah edi MIEEE CEng MIEEEnergy-Efficiency Research Group, D epartment of Electrical andComputer Systems Engine ering Monash University, Caulfield, Australia

AbstractFinding and developing new energy sources i s onlypart of the solution to world's long-term en erm needs.Making proper use of the energy presently a vailable isequally itnportant. Effective use of enera couldconsiderabtt. extend the life of existing fuel resources,and make the introduction of new sources much lessurgent. One possible alternative is Combined Heat &Power from stand-by-generators which the UnitedStates of dmerica have a relatively high capacity inthis regard. Many organizations dependent onelectricity have diesel generator sets as a backup inthe event offailure of main electricity supply. Recentlyit was noted that the local electricity had a peakdemand period covering times when the factories werenot operating and stand-by-generators were idle.Conversion of stand-by-generator facilitie s to CHPunits allows them to be used fo r profitablegeneration of electricity and heat. This pape r suggestsprinciples for conversion of stand-by-generatorfacilities to combine heat and power units. I t has beenlooked at the modification of the entire system toenable units to operate as a sustained basis and inp ar alle l ~ i t hhe main electricity supply. Sonre oj' hepractical dqjcukies, which can be encountered, aswel l a s spec ijc benejits, and methods to achieve themh m e been id entijed . In addition, author suggests someenergy conversion systems using single fuel to.si;iniirltnr2eoirs!v produce two forms of energy usuallyu.wji!I heat and electricity. The idea of conversion of.~~~ii~c/-b~~-~enerrrtoracililies to combined heat andp o w r tliscirssed in this paper i s praclical, prescriptiveant1 I ~orld wide application.

IntroductionAt prcsent. most of our energy co m a from burningfossil fucls: coal. oil and gas that cause major csisting

environmental pollution. Twenty years ago, nuclcarenergy was widely believed to be the energy sourcc ofthe future. Today, however, therc is a large questionmark over the world nuclear industry. Because ofenvironmental problems associated v it h p o w rgeneration from non-renewable sources. atlcntion hasnow turned to using e n e r a resources more cficientlyand also developing new and modern cncrgyconversion systems for better utilization of a\ailablcfuels. The dual use of fuel improv es cncrgy cfficicncyas compared to a facility which produces just onc formof energy. The end result is that less fucl is rcquircd toproduce a given amount of cnergq which could sawmoney and protect our environment. An cslcnsi\,cresearch program has bccn undcrtakcn by author toinvestigate the conceptions of increasing the cirrcicncyof power stations by impro \.ing thc utilization of non-renewable fuel and reduction of thcrmal \+astcs as \icIlas CHP, O generation projccts. ctc. part of bvhich uillbe eq la in ed in this prcscntation.

Electric power, an inefficient businessThe total amount of cncrgy gcncrated in po \\cr stationsin 1989 was cquivalcnt to iiiorc than '9000 million tonsof oil. A h u g amount of cncrg! is w st cd ci 'c n day.Every day, the aorld powr stations usc inorc than 4millions tons of coal. 6 million barrcls of oil. 50billions cubic mctcrs of natural gas an d 3 0 tons ofuranium. Thc total cncrgy thc! produce is inorc than20 0 billion nicga joulcs (=appro. 5.1000 iiiillion k W h ) .To producc this amount of cncrgq cvcq day ncarly60000 million kilogram carbon diosidc in pourcd intothe atmosphcre. Thc daily output of clcctricitj is only65 billion mega joules (18000 niillion kWh). Tlicn I3 Sbillion mega joulcs encrby is lost as \\ 'ask hcat \\hichcorresponds to releasing of 40000 million kilogram ofcarbon diosidc into thc atniosphcrc. An a ' c ragc ofonly about 33 % of thc cncrgy in its fticl is comcrtcd

0-7803-2129-4/94 $3.00 0 1994 IEEE


2/5

inlo electrical energy. Improvcnient in cficiency ofencrg) conversion systems hclps the presently availablefucl to last longer and to save the environment.

Funtlrmcntal design of Conversion of Stand-hy-Generator Facilities to CHP UnitsOnc possible alternative is Combined Hcat & Powerfrom staiid-b!-gcncrators. Wh ile the ratc ofimplcnicnVation or CH P systems in northern Europe isadiiiirablc. thew initiatkes rcquirc estensivcgo\.crnmcnt conimitmcnt. Many organizationsdcpcndcnt on clcctricity 1iai.c diescl generator sets asan insurancc in thc cvcnt of failure of main electricitysuppl! . The conversion to CHP allows them to be usedfor profitablc gcncration of both electricity and heat.Con\.crsion o f stand-by-gene rator facilities to CHP isachic\cd bj tlic addtion of heat cschanger to thegenerator and inodifiing thc control system to enableunits to opcratc on a sustained basis and in parallelwith the main clcctricity supply. Stand-by-generationfacilitics of Monash Mcdical Ccntrc were chosen forinicstigation. The aim of this investigation is tociduatc tlic actual levcl of savings achieved and theperformance of the systcm. taking into accountmaintenance costs, rcliability. heat generationcflicicncy, noise and othcr similar factors which wouldinfluence tlic adaptation of the technology in otherorganimtion. The main additional requirements are fora load sharing controller and syn chronising gear, so a ncnginc spccd control, a load anticipation unit and thencccssary synchronizing gear are incorporated. Thestand-b! -generation facilities origm ally cons ist of tw ounits. each 800 kW electric output. 50Hz, 1000 kV AStand-by, three phase star connection, 415 V, watercoolcd diesel. 1500 RPM. Heat rejection to coolant 529kW. eat rejcction to exhaust 807 kW. eat rejectionto alniosphere from engine 12 8 kW. eat rejection toatmosphere from generator 60 kW. igure 1 and 2show the simplified dmgram of the system. Conversioninvohcs installing the heat eschangers to recoverdlssipated heat from the engines and the addition ofclcctrical control system to enab le operation in p arallelto national grid. The heat output of the CHP unit isespected to meet the hospital steady state heat load.Mdf i c a t ions a re to be made to the engine's coolingsystems to incorporate engme jacket and exhausteschan gers in place of their or igmal radiators and fans.Figure 3 represents the block diagram of existingsystem and figure 4 represents the modified system.Figures 5 to 8 show the produced energy in and the

possibility of cncrgy rccovery from thc s\ .stcm.Convcrting stand-by-gcncrators to CH P is tcclinicallyand financially viable, and ultimate enhanccs thcavailability of the generators as stand-by plant. Price o felectricity gcnerated by stand-bygenerator facilitics iscompetelive to peak demand clcctricity pricc. Theintroduction of CHP on to a site results i n significantreductions in primary energy usage. The combinedheat and power plant can also be used intcgrated withan incineration plant, burning clinical and generalwaste.

mFigure 1 Simplified diagram of the system

National Grid

m IFigure 2 Simplified diagram of th e modified system

2697


3/5

SECNetwork6 6 k V

Trans-former

Figure 3 Block diagram of the existing system

SECNetwork1 66kV

MaditidSystem

pformerSystemContrdler0

I . I ,I + .. .. .. .Figure 4 Block diagram of the m odified system

529 liw;:e:y4YSTEM HeatRejection

Rejection to Coolantio . \tno.i.60 k\V

80 7eat7W Rejectionea tKrjcction to Aimoa.io Exhaust from Gen.from EnEincIFigure 5 Electricity and therriial heat

S29 k WHeatRejrction

SYSTEM

Rejcctioo io CoolanttoA h o r

lrsrfnl HrvtraiExchanger807 kW

Figure 6 Energy recove q from exhaust heat

SEC Nrhvork

Exchangrr529 k H

I wful I Ira1

SYSTEMHeatRcjertionto Almor

1 I

Figure 7 Energy recoven using waste heat

I I I II k n tExchanger807 kW I 'w iu l llcri

Figure 8 Integrated CH P and incincration plant

2698


4/5

Dual Use o f Fuel"Generation and C onversion Systems"Thc fact is that fossil fucl one da y will run out.EITccti\.c usc of this fucl would considcrably cstend thclifc of csisting fucl and makc introducing new sourcesmuch lcss urgcnt. A very niodcrn power station c.g. abrowcoal lircd powcr station can cont.ert 42Y0 f coalcncrgy into clcctricity. This cncrgy conversion ratio\\-as3 3% in 1050. This incrcasing of eficicncy lics ondcsign iinproirmcnt o r stcan1 turbinc and on furthcrdct.clopnicnt of thc m aterials which let high ertcmpcraturc today. If gas is uscd as fuel, then thecficicnc j can bc incrcascd to 5 2 % by combining of gasturbinc and stcam turbinc. Thc stcam turbine is derivedI\ illi thc stcam which is produccd from the thermali\astc of gas turbinc. If the thermal wastc from thestcaiii turbinc loop is uscd to produce the thermal heatfor hcating purposcs in rcsidcntial areas, then thatportion of the clcctricity gcncration decreases to about32% and lhc ulili/.alion of thc fuel for the generation ofclcctricit> and Iical at thc sanic tinie increases to 900/.Pouring tlic poison gases into the atmosphere will bercduccd b> furthcr devcloping of a new and modernpo w r gcncration systcms. The emission of CO2 canalso bc controllcd. In 1950, for example, 1120g CO2ha\z becn cinitting from a coal fired power station forc i q kilo watt hour generated electricity. In 1991 thisamount w s rcduccd to 88Og. From a combined gasstcam p w r station a still lower amount of CO2cmission, namclp. 38Og is cmitted for each lulo watthour electricity. The ultimate aim is actually burningo f fossil fucl with possibly rcleasin g no po llution. Thehigh cost of energy today. together with several otherfactors. such as reliability and quality of electricitysupply. makes this especially attractive to considerCHP facilities. CHP ystem conserves energy throughniorc cficicnt use of resources. Figure 9 showssimplificd conventional gas to electricity conversionsystcni. This system can be modified for waste heatrccovcry which has becn shown in Figure 10. Figures1 I an d 12 describe topping cycle CO generation whichinvolves first generating electric power, then usingexhaust heat lo produce useful thermal energy, as wellas bottoming cycle which involves first using fuel toproduce useful thermal energy for process use, thencapturing high temperature waste heat to generateelectricity.

Electricity 1 Furl

18Figure 9 Simplified gas to electricity conversionsystem

mFigure 10 Combined gas and steam turbine

1p'igure 11CO eneration

2699


5/5

Electricity

Turbine

IIenerator

steam

HeatingIndustr-in1 orRes.

Industry1- IFigure 12 CO eneration

Future of Conversion SystemsAuthor predicts that our future energy needs will besupplied by a combination of many M er en t sources,ranging from small wind and water wheels thatprovide power for a single home to central powerstations. Computer control systems will integrate theperformance of all these systems to make sure that asmuch as possible power comes from low cost andenvironmental friendlier sources. As alternativesources become more widely available, small scalesystems meeting local needs may start to replacecurrent larg e scale central power stations.

ConclusionFinding and developing new energy sources is onlypart of the solution to worlds long-term energy needs.Making proper use of the energy presently available isjust as important. Effective use of energy couldconsiderably extend the life of existing fuel resources,and make the introduction of new sources much lessurgent. Thc important aim of further development toincrease the efficienq of conversion systems is toimpro\,c the utilization of fuel and reduction of thermalttastes. This paper has suggested principles forconwrsion of stand-by-gencrator facilities to combinehcat and power units which is practical. prescriptiveand has world wide application. As a further work onthis project. using of CH P integrated with anincincration plant, burning clinical and general wastein suggcstcd.

References[l] IEEE Power Engineering Review June 1991,January 1992.[2] IEE Review, April 1992[3] BMFT-Publications, Bundesminesterium h e rForschung und Technologie, Bonn, Germ any[J] CADDET, EA, OECD 1991-1992 Publications[ 5 ] DPIE-Publications Energy Division ofCommonwealth Department of Primary Industry andEnergy, Canberra[6] Zahedi A. "Environnientally Acceptable P o w rGeneration, Power People Environment" CEPSIConference 1992 Hong Kong.[7] Lov, FM "Final Year Industrial Projcct. MonashUniversity", 1993

BiographvDr. Ahmad Zahedi received his Bacliclor ofEngneering(Electrica1) degree in 1974 from TchcranPolytechnic and Master of Engmeering(Nuclcar)degree in 1977 from Teheran University. Afterworking for 4 years with Atomic Encrgy Organisationof Iran as senior enginecr. he was awardcd thc long-term Scholarship of German Acadcinic ExchangeService to continue his education in Gcrniany. Hc uscdthis opportunity to obtain anothcr Master ofEngineering (Electrica1)degrcc and then Iic spcnt fouryears conducting ahanccd rcscarch andexperimentation in safcty analysis of nuclear powcrstations before being awarded a Doctorate froiii lhcRuhr Universily of Bochum. Dr. Zahcdi came toAustralia in 1988 and since thcn is a lecturer atMonash University: conducting research in the areas orconipulcr niodclling of power protcction de\ ices.e n c ru efficiency and dcvcloping integrated rcncu ableen er a and cncrgy storagc gstcnis.Author correspondence address is: Dcparlmcnt ofElectrical and Computer Systcnis Enginccring ofMonash Uniicrsity Caulfield Campus P 0 BO X 107.Caulfield East. Victoria. 3145 Australia Phonc:++hl 390 3 2005 Fax :++61 3 00 3 2906

2700

gerador diesel artigo traduzir

Documents