paper middleast n°19 13
DESCRIPTION
The bilingual Arabic/English trade magazine dedicated to the paper, board and tissue industry for the Middle East region By ENP Publishing GroupTRANSCRIPT
Edito
The economic profile of the Arab countries is di-verse. The oil importing nations are witnessing a moderate expansion, and the modest recovery
projected during the 2nd quarter is subject to intense shortcoming threats. For the other Arab states that are enduring political ins-tability and witnessing a transition phase, they are pon-dering on growth. With policy defenses mostly frail, the need for action for the overall stabilization and the growth oriented reforms is more than ever insistent.
The oil export countries are likely to bring a tangible growth during this period, in part due to Libya’s recovery taken steps. In the GCC countries, the very solid growth is maintained through the continuous increase in the eco-nomic and financial policies, and conformed monetary procedures.
Other concerned countries, like Lebanon, needs to consign safety nets for stability to safeguard and pro-tect the economy and the market from cuts back. The Lebanese industry sector having the unenviable times due to the escalating cost of production, and the fall in local demand caused mainly by the prevailing situation; the government needs to make consensus for the various critical political and economical turbulences, preventing illegal activities & competition in resources, but favoring tax exemption.
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The Magazine dedicated to the Pulp, Paper and Tissue Industry in the Middle East
Rima [email protected]
N°19 - Autumn 2013
Head Office / PublisherENP [email protected], rue Stanislas Julien - 45000 OrléansFranceTél. +33 238 42 29 00
PublisherSTÉPHANE RICHARD
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PAPER MIDDLEASTpulp, paper, tissue
magazine
2013
4 papermiddleast
Advertisers Index
APA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Cover 3Asten Johnson. . . . . . . . . . . . . . . . . . . . . . . . 19, 80BTG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39, 47Coldwater. . . . . . . . . . . . . . . . . . . . . . . . . . . 31, 71Fibretec . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33, 64
MIAC 2013 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7PaperEx 2013 . . . . . . . . . . . . . . . . . . . . . . . Cover 2PaperME 2013 . . . . . . . . . . . . . . . . . . . . . . . . . . 29Solaronics Bekaert . . . . . . . . . . . . . . . . . . . . 15, 68
Contents
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Paper Middleast 19Spring 2013
4 Newsletter subscription
News
6 MEPCO reaching 2 million Mt. at its facility
6 Jeesr Industries starting up a new tissue line supplied by Metso
8 NAPCO and the new core dryer machine installation project
8 VanTek to supply a Kraft Linerboard machine to a client in Egypt
9 Cost Optimization Project at Obeikan Paper Industries
Focus Lebanon – SIPCO(Société Industrielle du Papier et du Carton Ondulé)
10 Improving performance through skill management
16 -
Special Machine clothings
18the Drainage Property of Forming FabricBy Asten Johnson
30high speed packaging paper machines.
34 Evolution improves dewateringin the pressBy Voith Paper
36 Poorly maintained tension gauges may cause severe damagesBy Feltest Equipment BV
Focus Egyptian Update
38 The Egyptian Paper Industry two years after the revolution
News
SAUDI ARABIA
MEPCO reaching 2 million Mt. at its facility
MEPCO (Middle East Paper Company) based in Jeddah; Kingdom of Saudi Arabia announced having achieved a sizeable landmark of reachi-ng 2,000,000 metric tons production of packa-ging grade paper during March 2013 (over its past 10 years in operation).
Founded in 2001, the company started the pro-duction of sellable paper a year after with an annual capacity production of 100,000 metric tons at its mill located by the Red Seaport city of Jeddah, Kingdom of Saudi Arabia.
With Abdullah Almoammor; the Managing Di-rector & Sami Al Safran, the CEO of the compa-ny, Mepco takes pride in being the biggest mill in the MENA region. The mill currently manu-factures more than 1000 metric ton per day of sellable paper.
“We are very pleased to be the part of a premier company like Mepco, which is the largest privately owned paper mill in the region. We currently ma-nufacture recycled paper of international quality for box making industry ” Shaikh Faisal Mubin, MEPCO’s Marketing Consultant said.
Beside CCM (Corrugated Case Material) and Plasterboard of international norms, Mepco ex-panded to Plasterboard business without ham-pering current operations of RCM (Recycled corrugated Material).
“Mepco continues to grow! We are not yet a Public Stock Company, but we invested a lot in Techno-logy and Human Resources since our inception. We do not buy waste paper because it’s cheap but because we want to conserve natural resources to the best possible extent.We are 99 % based on our own collected recycled fi ber to produce higher brighter quality paper when we are producing Whitetop Liner and imitated KLB”, Shaikh Faisal added.
MEPCO is one of the largest privately owned paper manufacturer & producers of prime/pre-mium packaging board. The mill’s production of paper and paperboard were sold to more than 53 countries in Southeast Asia, Middle East, Africa and Europe.
The company currently runs 3 paper and board machines, with an annual installed capacity of more than 500,000 metric tons. The company intends to reach 1 million metric tons in manu-facturing different grades.
MOROCCO
Jeesr Industries starting up a new tissue line supplied by Metso
Jeesr Industries recently started up the fi rst state-of-the-art tissue machine from Metso in its mill in Berrechid (Casablanca surrounding) in Morocco.
The contract was signed in the mid of 2011,and the value of the order was never disclosed. Metso’s delivery includes a complete optimized production line with stock preparation equip-ment, an Advantage DCT 100+ tissue machine, a rewinder and wrapping equipment. The deli-very also comprises an extensive automation package including Metso DNA machine, pro-cess and integrated drive controls, and a Metso
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News
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News
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IQ quality control system with Metso IQ Fiber Weight Measurement.
“The production line smoothly came on stream ac-cording to plan and has been producing high qua-lity paper from the very start. This investment is very important to us, and we are happy to see the machine operating according to our targets having Metso fulfi lling our expectations” says Souheil Ba-daa, Chief Marketing Offi cer at Novatis Group.
Gunnar Söderqvist, Project Manager of Metso stated: “We are very satisfi ed with what the Jeesr team and Metso have achieved here. The facility has a compact and effi cient layout and both our crews have done a great job to ensure a smooth start-up as well as a continued optimal produc-tion”.
The new production line is designed to produce around 30,000 tonnes a year of high-quality fa-cial, toilet and towel grades mainly for the Mo-roccan market. The raw material is virgin pulp.
Jeesr Industries is a privately owned company, which is part of the Novatis Group, a producer and supplier of various consumer goods for the Moroccan market, among others; baby diapers.
Metso’s pulp, paper and power professionals specialized in processes, machinery, equip-ment, services, paper machine clothing and fi l-ter fabrics. The offering and experience cover the entire process life cycle including new pro-duction lines, rebuilds and services.
SAUDI ARABIA
NAPCO and the new core dryer machine installation pro-ject
NAPCO (National Paper Products Company) a Saudi paper packaging manufacturer installs a new core dryer machine at Dammam-based plant improving product quality and cutting
delivery time to better meet customer needs.
In line with continuous efforts to streamline manufacturing and improve plant capacity, Na-tional Paper Products Company reduces paper core curing and drying time by 40 - 60% with a new core dryer machine from Europe.
Furthermore, the new core dryer machine im-proves product quality with better and more even distribution of air, by changing direction of rotations and using metal mesh. The new machine operates on all paper cores above 5mm thickness and serves 3 key functions for temperature control: heating, cooling and dehu-midifi cation.
The new dryer machine will also facilitate NAPCO’s production process by offering pre-set drying plans ranging from 5 to 15 hours. These plans, which may be modifi ed, are pre-set based on key factors, including ambient tempe-ratures, ambient humidity, and core thickness as confi rmed by the NAPCO Management.
National Paper Products Company, located in Dammam, Saudi Arabia was established in 1956 to meet with packaging paper customer needs in Europe, the Middle East and Africa. NAPCO was the fi rst manufacturing plant of paper bags, cement bags, tissue rolls, and plas-tic crates in Saudi Arabia.National Paper Products Company is a member of INDEVCO Flexible Packaging, a division of INDEVCO Group.
EGYPT
VanTek to supply a Kraft Linerboard machine to a client in Egypt
VanTek; a Canadian machinery supplier sold the PM5 (a Kraft Linerboard machine) from the Moss paper mill in Norway; known previously as Peterson Paper Co. to a paper mill in Egypt.
The idled Kraft 2-layer Linerboard machine is complete, well preserved, and in very good condition. The machine is 5m wide and can produce around 160,000 tonnes/year of Kraftli-ner at a speed reaching 800 m/minute.
The buyer, who purchased the PM5, planned installing and starting up the machine at their mill in Egypt. The preparations to dismantle, pack the equipments and ship the paper ma-chine to Egypt have commenced and will be completed sometime in August 2013.
The Moss mill, which stopped production in April 2012 following bankruptcy proceedings, still houses a PM4 (a 4.5m wide Linerboard machine with 130,000 tonnes/year of output), an OCC pulp recycling line, and a Continuous Kamyr Kraft Pulp mill.
VanTek, Inc. has been serving the pulp and paper industry since 1984 and has grown into a world-wide leading source and supplier of used pulp and paper equipment and complete mills. The company is located in Vancouver and Washington with representative agents in China, India, Vietnam, Thailand and Indonesia.
KINGDOM OF SAUDI ARABIA
Cost Optimization Project at Obeikan Paper Industries
Obeikan Paper Industries had decided to up-grade its PM1 in order to increase its produc-tion from 180,000 to 220,000 tons (product mix). Similarly, Obeikan had invested in the recent development in coating technology cal-led “Curtain Coating”. Both investments cost roughly 100 million Sau-
di Riyals (around 27 Million Dollars) signed in the middle of 2011.
“The objective of PM upgrade is to increase Obei-kan’s cost competitiveness through economy of scale, while the curtain coating is mainly intended for having fl exibility for fi ber use, reducing pres-sure on white fi ber and opening a new door for new product development such as barrier coating and white top liner board”, said Eng. Mohammed Mowkley, Obeikan’s General Manager.
Hansol EME and Metso both are in charge for the upgrade on PM1. The stock preparation and wet end sections are supplied by Hansol EME, as well as the existing winder that will be replaced by a new one also from Hansol EME. While Metso, is to supply a new shoe press.
It is obvious that there are lots of challenges pa-per industries are facing nowadays, and Obei-kan view of such investments is to mitigate and predict what is going on. The growth in china putting pressure on fi ber, and the economy of euro zone that puts pressure on product selling price, had made the decision to do both invest-ments at the same time. These are going to posi-tion the largest board mill in MENA region and increase its competiveness on cost and quality as well.
The cost awareness is very important in any organization, but having innovation in place is more important; keeping you alive when you running at the edge. This is why Obeikan took the lead in the Middle East and invested in the recent curtain coating technology, becoming one of the leading users of such technology; added Mowkley.
The factory acceptance trials for main equip-ment’s such as Shoe Press and Winder is plan-ned soon and shipping will take place one mon-th after the trials period. The mill shutdown will be in Sep 2013 for 20 days, and will resume its operations in October 1, 2013. The execution of both investments will be car-ried out by Obeikan manpower with the Indian manpower support, and the supplier supervi-sion as well.
News
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Kfarshima a 5 Km2 town overlooking the Mediterranean Sea is located in the sou-thern part of Beirut, Lebanon. The town
managed to set itself among the most remar-kable Lebanese towns by hosting a variety of Industrial, Agricultural, Banking Commercial and Engineering facilities of which among the most remarkable ones is SIPCO, an industrial unit to manufacture corrugated board and egg trays, then Grey backboard.
Sipco (Société Industrielle du Papier et du Car-ton Ondulé) was a corrugated board company with 2 lines of production with printing and paraffin coating, both completely automated. The mill consists today of 2 plants, a paper machine recycling paper waste, and a molding machine producing egg tray bundles for local and export markets.
In the 60’s and 70’s of the last century, Leba-non and its capital Beirut bared 2 names the
“Pearl of the Middle East” and the “Swiss of the Orient”. It was at that time where the Ghan-dour family established their business in both confectionary and paper, and it was at that time that Sipco saw the light.
Back then, in 1965 precisely, Sipco was first ini-tiated to supply the Ghandour family confec-tionary products in cases for local market and to export both its products and other Lebanese products like (fruits and eggs) in the Middle East region (Iraq, Syria and other countries). Thus, it began with corrugated lines and a prin-
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SIPCO (Société Industrielle du Papier et du Carton Ondulé)
Improving performance through skill management
Focus Lebanon
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ting machine. The mill helped the corrugating board to fulfill its needs, the paraffin coating for wet products. Moreover, the mill made special products for specific customers, such as the cor-rugated double-double.
The first corrugating machine was installed at a time where this kind of investments was accounted for being a huge and unique invest-ment, considering the small number of citizens the country counted (around 2 million), and the small area it occupied (10,452 Km2).The wastes concern coming up from the cor-rugated machine, pushed the Sipco Manage-ment to implement a new recycling machine to produce two lines of Fluting and Testliner, in addition to an egg trays machine all from 100% recycled paper.
Five years later, in 1971, Mohamed Chafic Ghandour, Sipco’s General Manager expanded the mill’s activity by installing a second cor-rugating line and converting machine. Virgin Kraft brought from the USA, was used in the production process beside the mill’s Testliner and imitated Kraft.Both mill’s lines (at that time, the biggest in the Middle East), were installed to fulfill the need of the local, but mostly the Arab countries mar-kets.
In 1977, the company went to Chafic Ghandour and his children. As mentioned before, during the 70’s, Sipco was the biggest paper mill in the Middle East in down to business and producti-vity. But unfortunately not for long, since du-ring the civil war (1975-1990), the 2 corrugating
line machines were burned and were unable to perform anymore. As a result, the paper ma-chine had been converted into a board machine (Duplex Board), while the egg tray machine was saved and operational, as Mohamad Ghandour explained.
Today, Sipco occupies around 10,000 m2 of an area, and is the sole mill in Lebanon in the mar-ket of egg trays and Coated White Top Board, Grey Board and Green Kraft.
Keeping with high standards and performance in parallel to the commitment of the manage-ment and the very fast growing and demanding market, all this pushed Sipco’s management to follow up and keep up with the latest technolo-gies and innovations, hence the Sipco mill un-dergone continuous and regular upgrades and rebuilt during the 70’, 80’ and 90’s.
The PM1 was designed by DJM, Italy and the molding machine by Hartmann, Denmark.PM1 is a board machine and have 175 cm of width producing Coated White Top Board, Grey Board and Green Kraft with a daily production reaching 37MT at an operating speed reaching 100m/min. In the last decades, the machine un-derwent several rebuilt projects doubling both its speed and the production capacity.
The second machine is a paper molding ma-
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chine producing egg trays in different sizes with a production reaching 8 MT (750 bundles) per day. With the rebuilt processes during the past years, the machine was able to produce extra different moulds of egg trays.
Hartmann, Danemark and Esherwiess supplied the stock preparation for the molding machine, while several suppliers completed the need of the board machine with the necessary equip-ments;
preparation
Gerin, Mitsubishi, ABB and Telmecanique Autonics
Lowara Azmec, Bellin Pompe, KSB and
Varvel.
The graphs below show the production chart on each machine during the past 4 years:
The paper industry’s expansion and growth is constrained more and more and day after day by raw material availability and price fluctua-tion that the industry relies on more than any other factors. Many industrialists and paper makers stressed on that issue that needs to be dealt with and resolved at once. Water and high consumption of energy, accompanied with their high cost and other resources required for pa-per making, are still major obstruction as well for some paper mills that suffer from the proper government support.
Sipco’s mill relies for its production on waste paper that is collected locally and supplied by Lebanese companies right to the mill location. The challenge for any business is to manage and control the expansion and growth without sacrificing quality and efficiency of the compa-ny’s assessment. And a typical and successful business implies having the most important re-sources, the personnel of the company who are
Statistics showed that 95% of the company’s fu-ture clients are to be met at an exhibition which for many paper mills is part of their marketing strategy. Moreover, a competitor at an exhibi-tion will view a regular client as a potential cus-tomer, therefore an exhibition is an ideal oppor-tunity to present a product or show a service, as well to make direct contact with customers and clients.
Moreover, paper shows bring together different specialized companies, where visitors can easi-ly and quickly compare the product and/or ser-vice they need. Sipco Management attends in this regard the main paper shows held in the Middle East and Europe, such as Paper Arabia in Dubai, Paper Middle East in Egypt, MIAC in Italy among many others, bearing in mind esta-blishing a continuous relationship with their business partners and potential customers.The mill’s 2013 project is divided into 3 phases or subprojects: 1 - The work on the quality control system
(QCS) on the paper machine2 - The work on the stock preparation to in-
crease production and improve quality with Kadant Lamort, and
3 - The work on increasing production capacity with the help of the main supplier DJM.
At a second step, the Sipco Management will introduce the lamination section to its mill, aiming at absorbing the extra production and opening new markets.At this period of time when there is a big com-petition in the market’s demand, the mana-
the originators and form its core. Sipco is one of these companies whose main source for success and growth are the people who work for the company. More than 100 employees work for Sipco, with 7 Managers handling the market’s need in the different vital departments; the
Training is a procedure taken to enhance capa-bilities, skills and knowledge, thus is crucial for the company’s development and for reaching achievements. Training moulds the thinking of the employees and leads to quality performance of the employer as well. In Sipco, the manage-ment follows continuous training sessions for both the administrative positions and the tech-nical ones aiming at one hand to decrease acci-dents, and on the other to increase the efficien-cy, the performance and the productivity.
Sarah Hammoud - Procurement Manager
Khaled Sarhane - Production Manager
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gement of a company should be well aware about market forces that can disturb it. Since Sipco’s inception in the late 60’s in the export markets, that the company established a good relationship with its clients. Sipco is a custo-mer-oriented company for emphasizing on the quality of end products, taking into considera-tion some special sizes and substances that cer-tain clients ask for. In addition to that, Sipco makes sure for timing of the orders and having short delivery periods.
The mill’s output goes to the printing press industry mainly outside Lebanon (Egypt, Syria,
Jordan, Iraq, Sudan, Saudi Arabia and Greece), and to farms mainly inside Lebanon for the egg trays production. Noting that, around 15% of the mills’ production, is used domestically.
helps reduce the negative impact an industry can induce on the environment; since it can preserve natural resources. Industries can help the environment in different ways by using products made from recycled material, which is the case of Sipco that manufactures 100% recycled paper/ wood free products.
On the other hand, working on and supporting environmentally friendly techniques, attract new customers who want to go with the “Go Green” concept, and who search to buy pro-ducts and services from an environmentally friendly business.
“The word recycling in its self is a friendly environ-ment procedure when you reuse paper wastes. Also the reuse of rejected water or water wastes during production, in addition to newly working on pro-ject Integrated energy efficiency solution”, Moha-mad Ghandour concluded.
Holding a deep belonging to the Ghandour family, Mohamed Chafic Ghandour, Ge-neral Manager of Sipco, a down to earth
personality, and a charming figure of Lebanon is today on the light.
First, I would like to express my content-ment of having this discussion with you. Second, I would like to know who is Moha-med Ghandour.
I was born in Beirut on May 1946. I first at-tended College De La Salle school, moved to IC college and then Centre Belge in Beirut.In the early 60’s I started work at the Ghandour confectionary factory, first as a worker on the biscuit line (ghandour), and later as a trainee at the Accounting Department. In the late 60’s, I took in charge of Sipco Mana-gement.
Why SIPCO was established and when?
The main reason was to supply the needed cases for exporting of the family owned factory.
In 1965, the local suppliers didn’t have enough capacity to supply us with cases.So, the vision was to have an integrated produc-tion facility for the packaging of the confectio-nary products. Later, I took in charge of Sipco (in the early 70’s), modernized the company to fulfill the needs of the packaging corrugating market at all levels, with full automatic lines and all categories of products.As we are not anymore in the corrugating pro-duction since the lines were destroyed during the war, I am developing today the production on the paper machine, mainly for coated white top grey board in reel and sheets.
And what makes SIPCO special?
Sipco is special because it is the only producer of coated white top grey board and egg trays in Lebanon. Our machine is specialized; having the right equipments and expertise in coating. Besides, nobody ever invested in this kind of industry before. For all this, Sipco is special.
…Good to hear that Mr. Ghandour, and I wish you prosperity.
Now, would you please brief us on the cur-rent situation of the paper & board indus-try in Lebanon?
The board industry curve was ascending 2 years ago, but unfortunately since mid 2011, the curve went down and I guess my collea-gues in the same field share me same opinion (excuses for talking in their names).And this year, at a high descending speed export is diminishing and energy cost is getting higher and higher, adding to that the labor cost increased.
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I believe we need support programs from the government, check the European countries, En-gland and Germany for example when govern-ment banned the usage of coal and obliged the reduction of CO2 emission, it assisted and gave huge support for the manufacturer each in this field, precisely in the energy cost, by paying the extra cost of fuel price.
And what made the curve go down?
Beside the global economical crisis, and inter-national descending curve in paper industry, the raw material & energy high cost, labor cost compared to Asian countries, had their influence on this curve.In addition the conflict in Arab countries; like Egypt and Syria had a great negative impact on production capacity and sales volume, since they had the biggest share of our production; also other Arab countries couldn’t be reached by land freight which couldn’t be replaced by economical rate via sea freight like Saudi Ara-bia for example.
So, what are the required solutions?
The only and urgent solution is reducing cost of energy in addition to preserving our raw mate-rial. The Arab countries put duties on expor-ting the raw material like Jordan and Egypt for instance, while others forbade it like Syria, I believe we should do the same.
China today is sucking the world raw material (waste paper) importing mainly from Europe and the US. On the other hand, Europe is no longer coun-ting on wood to make its raw material (which environmentally is a wise decision), but this in-duced the cost of raw material to go high world-wide, and China’s huge consumption made the
cost go higher and higher, adding to that the energy and labor cost that also went up, as I mentioned earlier.
How does Lebanon being on the map of exploiting oil and gas help the economical sector and the paper industry in particu-lar?
It is a very promising and encouraging dream, but can we survive as industry till that time?!
You talked earlier about the Arab conflict, my question is: what procedures the com-pany took following the migratory waves of the conflict in the bordering and surroun-ding countries?
As we were obliged to reduce production be-cause of stoppage of export, we are trying to cut on our fixed costs, this is the most important action to be taken now. Also searching for mar-kets with the possibility of sea freight shipping, since land freight had became very expensive as I said before.
And far from work, what hobbies do you practice Mr. Ghandour?
Mainly jogging in the early morning, hiking to breathe fresh air and feel the liberty, to get in touch with nature leaving the office stress behind. I also go for skiing when work permits.
Interesting! And how would you like to conclude this interview?
We the industrialists; mainly in the paper in-dustry sector, and the Association of Arab Pa-per Industries, must take lessons from Europe regarding our sector. We must find solutions to protect ourselves from the countries that are sucking our raw material, and where their labor cost is much cheaper than ours, because they are invading our market!So, let us join our forces for specialization by categories, thus, stop individualism in the way of thinking, and let us consolidate mergers.
Thank you for your time, wishing you all the best!
Machine clothings
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Abstract
The 3D structures of three different types of triple layer fabrics are investigated based on the X-Ray micro-tomography and 3D modeling. It is found that the sheet support binder (SSB) fabric and the warp tied fabric have a very open structure between the top layer and the bottom layer of the fabric. In a warp integrated sheet support (WISS) fabric, however, all MD yarns pass from the top layer to the bottom layer and thus create a unique center layer between the paper side and machine side of the fabric.
Laboratory drainage testing indicates that, compared to SSB and warp tied fabrics, the WISS fabrics drains slower at low sheet basis weights (< 15 ~20 g/m2). However, the WISS fabric drains faster when sheet basis weight is higher than 20 g/m2. It is found that the resis-tance created from the center layer retards the initial impingement drainage which leads to a slower drainage of the WISS fabric at low sheet basis weight. On the other hand, because of the higher center plane resistance, fibers have less tendency to plug the drainage holes in a WISS fabric, which leads to a high drainage rate at higher sheet basis weights.
A Pilot papermaking trial confirms that, be-cause of the center plane resistance, the WISS fabric will retard the initial high impingement drainage and shift the drainage downstream on the forming table.
Introduction
The sheet forming process is essentially a pro-cess that drains water through the voids between
the filaments of the forming fabric while fibers are retained to form a mat on top of the fabric. Over the past 50 years, forming fabrics have evolved from bronze wire, to synthetic single layer, double layer, and triple layer fabrics.
In the past decade, triple layer forming fabric designs have gained wide acceptance world-wide. The triple layer fabrics combine a fine pa-permaking side fabric to a coarser machine side fabric held together by a stitch or binder yarn. The evolution of triple layer forming fabrics is associated with the improvement in binding technology [1, 2].
The first generation triple layer fabrics used a single cross-machine (CMD) oriented binder yarn to integrate the two fabric layers. Figure 1 (a) shows an example of the first generation of forming fabrics. In this example, the paper side fabric and machine side fabric are stitched with a CD binder yarn that can be seen in the CD section.
The second generation of triple layer forming fabric is commonly referred to as SSB (sheet support binder) fabric. In a SSB fabric, CD bin-der yarns are part of the structure tying the top to bottom and partly supporting the sheet (Fi-gure 1 b). The binder yarns are woven as pairs so that when one is on the top surface the other is in the bottom.
The third generation of triple layer forming fabric uses machine-direction (MD) oriented warp yarns to bind the paper side fabric and machine side fabric. Similar to SSB, in a warp tied fabric, the warp binder yarns are woven as pairs so that when one is on the top surface the other is in the bottom. In terms of the fabric
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structure, the major difference between a SSB fabric and a warp tied fabrics is that the tie strands are CD yarns in a SSB fabrics, while the tie strands are MD yarns in a warp tied fabric.The fourth generation of triple layer fabrics is commonly referred as Warp Integrated Sheet Support (WISS) fabric. The WISS fabric uses all of the MD yarns to form both the top plain weave and the bottom woven structure. Com-pared with a warp tied fabric, all MD yarns are woven in pairs in a WISS fabric (Figure 1d). When a MD yarn goes from papermaking side to the machine side of the fabric, it creates a long float in the center section of the fabric. Because all MD yarns have long floats between the top and bottom layer, the WISS fabrics have a totally different structure compared with SSB and warp tied fabrics, especially in the center layer of the triple layer fabrics.
Since the commercialization of triple layer for-ming fabrics in the 1980’s, the research and development on triple layer fabrics have been focused on the top layer using fine yarns and normally a plain weave structure to provide a fine papermaking surface. On the bottom layer, the focus has been on the use of larger diame-ter CD yarns or new materials to improve sta-bility and wear resistance. Almost no research has been conducted to study the effect of the center layer of forming fabrics on drainage pro-perties and sheet forming. Danby and Johnson [3] found that the structure in the center layer of a triple layer forming fabrics will create a significant resistance to the total flow through the fabric. It was proposed that the resistance created in the center layer of the fabric (Center Plane Resistance) will directly affect the initial impingement drainage on the paper machine [3].
In this paper, we will compare the drainage properties of three different types of triple layer forming fabrics --- SSB, warp tied fabric and WISS fabric. The 3D fabric models based on X-Ray micro-tomography, the lab drainage testing results, and the data from a pilot paper machine trial will be presented to support the Center Plane Resistance theory.
Experimental
DRAINAGE APPARATUS
The Gravity Sheet Former (GSF) was deve-loped to determine the drainage properties of forming fabrics. Figure 2 is a schematic of the GSF used in this study. A rectangular column with a height of 150 cm and a uniform cross section area of 2.54 cm by 7.87 cm is made with Pexiglass. This Plexiglass column is attached to a shoe shaped sheet former with an opening of 7.87cm (CMD direction) by 8 cm (MD direc-tion) in the bottom. The height of the “shoe” is 5.5 cm. The forming fabric is inserted into the bottom of “shoe” from the opening in the side of the apparatus. Two orienting vanes are installed inside the “shoe” to create a flow in the MD direction of the fabric and to distribute the flow evenly.
During the testing, water is filled from the bot-tom of the former until it reached 127 cm (50”) height in the column. A calculated amount of pulp is injected from the bottom of the column through a syringe. When the valve under the fa-bric is opened, fibers suspended over the “shoe” will first drain through the fabric and form an oriented fiber mat over the fabric. After the fiber mat is formed, the remaining water in the plexi-glass column will continue to drain through the fiber mat and fabric. While the water and fiber suspension is draining through the fabric, the
Fig. 1. Triple layer fabrics with different binding technology. (a) CD yarn binder; (b) Sheet support binder; (c) Warp tied binder; (4) Warp integrated sheet support binder.
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water level in the column and pressure over the fabric is recorded continuously at a sam-pling frequency of 50 Hz through an ultrasonic proximity sensor on the top of the column and a pressure sensor 5 cm over the fabric. The total drainage time is also recorded by the laser de-tector on the bottom of the Plexiglass column. A Labview program was written to control water filling, draining and data acquisitions.
FABRICS
To compare the drainage properties of the dif-ferent types of triple layer forming fabrics and to better understand the effect of center plane resistance on the drainage property, a SSB fa-bric, a warp tied fabric, and a warp integrated sheet support (WISS) fabric were selected in this study. All fabrics have a plain weave in the paper side and similar air permeability. The major properties of the fabrics are shown in Table 1.
MEASURING DRAINAGE RESISTANCE OF FIBER/FABRIC
SYSTEM
When fibers deposit on the fabric, they will block the drainage hole and be embedded into the forming fabrics. The interaction between fibers and fabrics will create a resistance to the water flow. As more fibers approach the fabric, a layer of fiber mat will be formed over the fa-brics. Ingmanson and coworkers [4, 5] showed that Darcy’s law and a material balance on the solids led to the following expression for the drainage velocity v(m/s) through a fibrous mat:
(1)
Where,A = filtration area, m2
dV/dt = volumetric flow rate of the filtrate, m3/s - Pt = total pressure drop across the fibrous mate and wire, Paµ = viscosity of the filtrate, Pa·sRt = total drainage resistance from fiber mat and forming fabric, m-1
In the GSF drainage system, the relation between drainage velocity over the forming fabric and the drainage velocity in the water co-lumn can be shown by the following equation:
(2)
Where Ac = cross section area of water column, m2
h = height of water in the column, (m)
At low flow rate, the pressure drop is provided by the weight of water in the Plexiglass column:
(3)
Where = water density (kg/m3)By combining Equa-tion (1), (2) and (3), we can obtain:
(4)
Solving differential Equation (4), we can obtain the relation between
Fig. 2. Schematic of Gravity Sheet Former (GSF)
Table 1. Characteristics of fabric samples
Sample AirPerm(cfm)
Paper Side Properties FiberSupportIndex
Drai-nageIndex
Mesh x Knoc-king
MDyarn (mm)
CD yarn (mm)
Drai-nage
area (%)
SSB 370 94x90 0.13 0.13 29.1 180 33.3
Warp Tied
375 95x82 0.15 0.13 25.5 173 30.8
WISS 380 81x90 0.17 0.13 24.7 174 32.4
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water height in the column (h) and the time (t):
(5)
Equation (5) shows there is a linear relation between ln(h) and drainage time t. If we plot ln(h) vs t, Rt can be obtained from the slope of the plot since other variables are all known in Equation (5).
Figure 3 shows an example of the water height in the column changing with time. In this example, a 25gsm sheet was formed. As can be seen from the graph, it took about 0.5 second to form a fiber mat on the fabric. After the fiber mat was formed, there was a good linear rela-tion between lnh and t. From the slope of the curve, Rt can be obtained.
In this study, the total drainage resistance of the fabrics at different target basis weights ranging from 0 to 55 g/m2 was measured. Because fiber retention has a significant effect on total drai-nage resistance and different fabrics have dif-ferent retentions even at the same target basis weight, we adjusted the total drainage resistance based on the actual sheet basis weight through a linear fitting. By doing this, we were able to compare the drainage resistance of different fabrics at exactly the same sheet basis weight. It was found that, after taking account of the va-riations in sheet basis weight, the repeatability of experiments increased significantly and the variations between repeat measurements were normally less than 5%. In this study, all drai-nage measurements were repeated three times and the drainage resistance at each condition
was calculated by averaging the results from the three measurements.
X-RAY MICRO-TOMOGRAPHY AND 3D MODELING OF
FORMING FABRICS
In order to study the internal structure of the forming fabrics, X-Ray micro-tomography was used to obtain the cross section images of the fabrics. A fabric with a size of 5x5 mm was scanned using micro-CT scanner. After the CT scan, the MD_ZD and CD_ZD cross section images of the fabrics were reconstructed. The distance between each cross section is 4.5 um. Image analyzing software was written to trace the cross sections and coordinate of each yarn in a 3D domain. Based on the coordinates of the yarns, each individual yarn can be modeled using 3D CAD software. After assembling all MD yarns and CD yarns together, we will be able to obtain a 3D model of the fabric.
Results and discussions
CONSTRUCTION OF TRIPLE LAYER FABRICS
SSB fabrics are the most commonly used triple layer fabrics. In the past few years, warp tied and warp integrated fabrics gained more accep-tance because of these benefits: low caliper, low drive loads, improved drainage, and high couch solids. To differentiate these three types of triple layer fabrics, it is necessary to understand how these three types of fabrics are woven.
Figure 4 shows the construction of a typical SSB fabric. The ellipses represent the paper side and machine side MD yarns, respectively. In the paper side of the fabric, two CD yarns are shown. These CD yarns weave with MD yarns and form a plain weave paper side (Figure 4 (a)). The top layer and bottom layer of the fabric are tied together by two CD binder yarns (Figure 4(b),(c)). These two binder yarns are woven as pairs so that when one is on the top surface the other is in the center or bottom of the fabric. In the machine side of the fabric, a larger CD yarn weaves with MD yarn to form a 6 shed bottom (Figure 4 (d)).
Fig. 3 Change of water height in the column with time.
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Figure 5 shows the construction of a typical warp tied fabric. Here, the ellipses represent the cross section of the paper side and machine side CD yarns. In the paper side of the fabric, one CD yarn is shown. It weaves with MD yarns and forms a plain weave paper side (Figure 5 (a)). The top layer and bottom layer of the fa-bric are tied together by two MD yarns (Figure 5(b), (c)). These two binder yarns are woven as pairs so that when one yarn is in the paper side, the other yarn goes to the machine side to tie the two layers together. In the machine side of the fabric, a MD yarn weaves with CD yarns and forms a 6 shed bottom (Figure 5 (d)).
Figure 6 shows the construction of a typical warp integrated sheet support (WISS) fabric. Here, the ellipses represent the cross section of the paper side and machine side CD yarns,
respectively (Figure 6 (a)). Two MD yarns are woven in pairs so that when one yarn is in the paper side, the other yarn goes to the machine side to tie the two layers together (Figure 6 (b)). Repeating the above weave pattern, the top and bottom layer of fabrics are tied together by all of the MD yarns (Figure 6 (c), (d)). Since all MD yarns have long floats between the top and bot-tom layer, the WISS fabrics have a totally dif-ferent structure compared with SSB and warp tied fabrics. We will compare the 3d structures of these three types of fabrics in the next sec-tion.
3D STRUCTURE OF FORMING FABRICS
To better understand how a forming fabric affects the drainage, it is necessary to unders-tand its internal structure because the drainage is not only affected by the surface property of the fabric, but also the center and bottom layer of the fabric. Various past studies have attemp-ted to characterize the structure of the fabrics. Some methods were based on encasing fabric samples in plastic, followed by grinding and po-lishing to observe the cross-sections [6]. Howe-ver, these methods were largely focused on the two dimensional properties, typically open area. Another approach has been the compu-ter-based creation of three-dimensional models of fabrics [7]. However, this approach has not fully modeled the knuckling and deformation of filaments - key factors in three-dimensional structure. Adebar [8] used machining to expose the cross sections for a fabric potted into resin and then build 3D models based on the cross
Fig. 4. Construction of a Sheet Support Binder (SSB) fabric.
Fig. 5 Construction of a warp tied fabric.
Fig. 6 Construction of a WISS fabric.
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section images. The model reflects the true structures of the forming fabric. However, the machining process is very time-consuming and the cross section images are not very clean and clear.
In this paper, X-Ray micro-tomography was used to obtain the cross section images of the fabrics. Since this is a non-intrusive technique and the CT scanner has a resolution of 4.5um, we are able to build a model which reflects the accurate 3D structure of a forming fabric.
Figure 7 shows an example of 3D models for a SSB fabric. With 3D software, we are able to rotate the models and to observe the internal structure of the fabrics from different angles. We are also able to slice the fabric to expose any cross sections of the fabric. Fig. 8 (a), (b), and (c) show the MD_ZD cross sections of the fabrics used in this study.
It is obvious from Fig. 8 (a), the SSB fabric has a very open structure along section AB between paper side and machine side of the fabric. There is nothing except pair of binding yarns in the center plane of the fabric.
Similar to SSB fabric, there is also a quite open space between paper side and machine side of the warp tied fabric (Fig. 8 (b)). Despite part of the view was blocked by the tie stands, we can still find a gap between paper side and machine side, although the width of the gap is smaller compared with that of SSB fabric.
It is evident from Fig. 8 (c) that, compared with SSB and warp tied fabric, WISS fabric has a much less open structure in the center plane of the fabric. Since all MD yarns will pass from
the paper side to the machine side and these yarns have a long float in the center layer of the fabric, these MD yarns create a unique layer between the paper side and machine side of the fabric.
To compare the center plane of the different types of triple layer fabrics, the 3D models were cut through the open space between top and bottom layer of the fabrics (dash line AB in Fig. 8). Fig. 9 shows the center plane of the different types of fabrics used in this study.
Fig. 9 confirms that there is a large open space between the top and bottom layer of SSB and warp tied fabrics. Image analyzing indicates that the percentage of the filling is 13.3% for a SSB fabric and 4.5% for a warp tied fabric. However, for a WISS fabric, the percentage of
Fig. 7. 3D models of a SSB Fabric. (a) paper side; (b) machine side.
Fig. 8. MD_ZD cross sections of the forming fabrics. (a) SSB fabric; (b) warp tied fabric; (c) WISS fabric.
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the filling is 32.2%. As shown in Fig. 8 (c), the high filling is mainly caused by the float of MD yarns in the center of the fabric, although some of the knuckles from the machine side CD yarns also contribute to the high percentage of filling.
It is well known that the drainage property of a forming fabric will not only be affected by the paper side of the fabric, but also be affected by the machine side of the fabric. Evidence for this has been suggested in recent studies of fabrics modeled as rows of cylinders [9]. Under certain conditions, rows of large diameter cylinders on the downstream side induced non-uniformities in the flow entering the row of small diameter cylinders. Since the WISS fabrics add an addi-tional layer in the center of the fabric, it is hi-ghly possible that the center layer may create resistance to the flow and thus affect the total drainage. In the next section, we will compare the drainage properties of the WISS fabric with that of the SSB and warp tied fabric and find out how the resistance from the center plane affects the drainage.
DRAINAGE PROPERTIES OF DIFFERENT TYPES OF
TRIPLE LAYER FABRICS
To compare the drainage properties of different types of triple layer fabrics, the drainage resis-tance of fiber/fabric system at different sheet basis weights was measured. Table 2 shows the total drainage resistance from fabric and fiber mat at sheet basis weights from 0 to 53 g/m2
when SSB, Warp tied and WISS fabric are used. Please note that the drainage resistance has been corrected based on the actual sheet basis weights.
As shown in Table 2, the WISS fabric used in this study has the same drainage resistance as that of the warp tied fabric and 5% higher drai-nage resistance than that of the SSB fabric if there is no fiber deposit on the fabrics. When fibers start to deposit on the fabrics, at low basis weight (4 and 12 g/m2), the WISS fabric has higher drainage resistance than that of SSB and warp tied fabric. However, at higher basis weight (> 27 g/m2), the WISS fabric has lower drainage resistance compared with the SSB and the warp tied fabric.
Fig. 10 shows the percentage difference when compared the total drainage resistance of the WISS fabric with that of the SSB fabric and warp tied fabric. If the difference is >0%, the WISS fabric has a higher drainage resistance and drains slower. On the other hand, if the difference is <0%, the WISS has low drainage resistance and drains faster. It is obvious form Fig. 10 that at low sheet basis weight, the WISS fabric drains slower compared to SSB and warp
tied fabric. Howe-ver, at higher sheet basis weight (>20 g/m2), the WISS fabric drains faster.
The different drai-nage property between the WISS fabric and
Fig. 9. The center plane of different types of forming fabrics. (a) SSB fabric; (b) warp tied fabric; (c) WISS fabric
Table 2. Drainage resistance (m-1)
Fig. 10. Comparison of the drainage resistance of the WISS fabric with that of SSB and warp tied fabric.
Sample Sheet Basis Weight (g/m2)
0 4 12 19 27 38 53
SSB 8.0 12.7 34.4 55.9 91.9 142.1 222.0
Warp Tied 8.4 16.4 38.2 60.8 97.6 145.1 228.6
WISS 8.4 18.7 39.0 56.5 89.2 134.5 215.1
26 papermiddleast
other triple layer fabrics can be explained by “Center Plane Resistance” theory. As shown in Fig. 8 and Fig. 9, the WISS fabric has a totally different center plane than that of SSB and warp tied fabric. At low sheet basis weight, the flow will not only be affected by the top surface of the fabric, but also be affected by the yarns in the center layer. A back pressure will be created if the yarns in the center layer are right below the drainage holes. In other words, the center layer will create resistance to the flow and the resistance from the center layer will contribute to the total drainage resistance. On the other hand, since SSB and warp tied fabrics have a quite open structure in the center layer, the re-sistance from the center layer is much smaller compared to WISS fabric.
At high basis weight, a layer of fiber mat will be formed on the fabric. Early drainage experi-ment and SEM images by Herzig and Johnson [10] indicated that when fiber mat formed on a forming fabric, the fibers were drawn prefe-rentially to the openings of the top surface and thus added hydraulic resistance. It was sug-gested that significant coverage of the knuckles of the forming fabrics does not occur until basis weights are greater than 10 -15 g/m2 [10]. When the sheet basis weight is larger than 20 g/m2, the total drainage resistance is mainly determined by the fiber mat over the fabric, although the fabric itself contributes a small amount of resis-tance to the total drainage resistance.
Compared with SSB and warp tied fabric, the WISS fabric has higher drainage resistance from the center layer and less straight through drainage. When fibers deposit on the fabric, because of the high drainage resistance and less straight through drainage, fibers have less tendency to embed into the fabric or to plug the drainage holes. The first layer of fiber mat (~ 15 g/m2) is formed relatively gently over the fabric when compared with fiber mat formed on SSB and the warp tied fabric. This interface layer has a lower drainage resistance compared with the interface layer formed on the SSB and the warp tied fabric. Therefore, when the sheet basis weight is higher than 20 g/m2, the total drainage resistance is low and the WISS fabric
will drain faster compared to the SSB and warp tied fabric.
The above explanation can be verified by the wire marks of the sheet formed on the fabric. Fig. 11 shows the surface images of the hands-heets formed on the warp tied fabric (a) and the WISS fabric (b). The images were taken under the low angle reflection light. It is evident from the images that the wire mark of a sheet formed on the warp tied fabric is more obvious than that of the sheet formed on the WISS fabric. The wire marks in the handsheets confirm that the degree of fiber embedment is much higher when the sheet is formed on a warp tied fabric than when formed on a WISS fabric.
DRAINAGE RESULTS FROM PILOT PAPER MACHINE
TRIAL
In a modern paper machine, with the increase of machine speed and impingement angle, the peak drainage pressure can become very high [11]. The first part of the sheet to form will ex-perience very high forces that tend to embed fiber in the fabric and create sheet sealing. The-refore, it is necessary to design a fabric that can retard the early drainage while still retaining the drainage capability at the later stage of the forming.
We have already shown through 3D modeling and lab drainage testing that, compared with SSB and warp tied fabric, the WISS fabric will create a higher resistance to the flow at the ini-tial drainage stage. In order to verify that the WISS fabric can retard the impingement drai-nage in a paper machine, a pilot papermaking trial was conducted at Greenhouse Packaging, Sweden in April, 2008. The pilot machine is a very good representation of a modern packa-
Fig. 11 Wire marks of sheet formed on the warp tied fabric (a) and WISS fabric (b).
papermiddleast 27
ging grade machine, with a long bottom wire section consisting of forming board, Vac-Foil units and wet suction boxes. The machine was configured as a fourdrinier with a BelBond top wire dewatering unit. The fiber stock used in the trial has 70% virgin fiber and 30% OCC. During the trial, the machine speed was set at 750 meter per minute and sheet basis weight was controlled at 171 g/m2.
Three forming fabrics were tested during the trial. Table 3 shows the properties of the fabrics used in the trial. Two SSB fabrics were used in the trial. The major difference between these two SSB fabrics is that the SSB_A has a higher caliper than that of SSB_B. As shown in Table 3, the SSB_B has a similar caliper as that of the WISS fabric.
During the trial, the drainage was measured at different sample points starting with the forming board by a Metso Consistency meter, which is a micro wave device that measures the amount of water present in the paper stock or web.
Fig. 12 shows that, starting with the forming board (sample point 1), both SSB_A and SSB_B have a fast initial drainage. At sample point 3, more than ¾ of the water in the stock is drai-ned. However, for WISS fabric, the initial drai-nage is more gentle and only ¼ of the water is drained at sample point 3. The majority of the water in the stock will continue to drain through the fabric at sample point 4 and 5. It is obvious from Fig. 12 that, compared with SSB fabric, the WISS fabric retards the initial high impingement drainage and shifts the drainage to the downstream of the forming table.
Since the three fabrics used in the trial have similar air permeability, similar drainage area, similar mesh and knocking, the difference in drainage properties can only be explained by the difference in fabric internal structure. The results from the trial verified that fabrics with a higher center plane resistance will retard the initial impingement drainage and form a layer of fiber gently over the fabric.
It is well known that reducing impingement drainage is beneficial to the papermaking. The major benefits of low impingement drainage include:
the fabric structure;
retention;
turn will result in a cleaner return run on the paper machine;
-bric;
Sample Air Perm (cfm)
Paper Side Properties FiberSupportIndex
DrainageIndex
Caliper(mm)Mesh x
KnockingMD yam (mm)
CD yam (mm)
Drainagearea (%)
WISS 490 63x59 0.2 0.18 29.4 120 28.7 0.99
SSB_A 490 63x54 0.2 0.19 30 114 26.5 1.25
SSB_B 520 63x60 0.2 0.18 29 122 31.2 1.04
Table 3 fbarics used in the pilot trial
Fig. 12 Amount of water present in the web at different sample points
With the commercialization of the fourth gene-ration triple layer WISS fabric, it is expected that more results related to above benefits will be re-ported from field trials. We will present some of the commercial trial results in the near future.
Conclusion
By combining X-Ray micro-tomography and 3D fabric modeling, we are able to compare the in-ternal structure of three different types of triple layer fabric. The major difference between the WISS fabric structure and the other types of triple-layer fabrics is that the WISS fabric has low drainage area in the center layer of the fabric. At low sheet basis weight, the resis-tance from the center plane will increase the total drainage resistance and thus reduce the drainage rate. However, at higher sheet basis weight, the center plane resistance will prevent the fiber embedment and reduce plugging in a WISS fabric structure which will then allow fas-ter drainage at high sheet basis weights.
The pilot papermaking trial confirmed that the center plane resistance in WISS fabric will re-tard the impingement drainage without sacrifi-cing the total drainage.
References
1. DANBY, R., PERRAULT, J., “Weaves of Papermaking
Wires and Forming Fabrics”, PAPTAC G18 Data Sheet
(2003).
2. HENDER, B., “Efficiency Improvement Through the
Use of Warp Exchange Technology”, TAPPI/PIMA Pa-
perCon’08 Conference, May 4-7 2008, Dallas, TX.
3. DANBY, R., JOHNSON, D., “Float Forming”, PAPTAC
92nd Annual Meeting 2006, C142 – C148.
4. IMNGMANSON, W.L., “An investigation of the Mecha-
nism of Water Removal from Pulp Slurries”, TAPPI
35(10):439-448 (1952).
5. IMNGMANSON, W.L., WHITNEY, R,P., “The Filtration
Resistance of Pulp Slurries”, TAPPI 37(11):523-533 (1954).
6. HELLE, T., “The Influence of Wire Structure on Sheet For-
ming”, Paper Techn. and Ind. 21 (4), 12 (1980).
7. ADANUR, S., TIANYI, L., “3D Modelling of Textile Com-
posite Preforms”, Composites Part B: Eng. 29(6): 787
(1998)
8. ADEBAR, T.K., “Imaging the Three-dimensional Structure
of Forming Fabrics”, TAPPI JOURNAL 6(8):12-15 (2007)
9. HUANG, Z., OlLSON, J.A., KEREKES, R.J., GREEN, S.I.,
«Numerical Simulation of the Flow around Rows of Cylin-
ders», Computers and Fluids, vol. 35, no. 5, pp. 485-491,
June 2006.
10. HERZIG, R., JOHNSON, D., “Investigation of Thin Fiber
Mats Formed at High Velocity”, TAPPI JOURNAL 82(1):
226-230 (1999).
11. JOHNSON, D., “Effects of Jet Impingement on Bel Baie
Machines”, Pulp & Paper Canada 93(5):12, 14-15, (1992)
28 papermiddleast
Machine clothings
30 papermiddleast
Designing World Speed Record felts for high speed packaging paper machines.
By M.Quarti, M.Lampart - Press Fabrics Designers, Cristini Group
An important project
In March 2010 the ProPapier Group started up in Eisenhüttenstadt their PM2, the world’s big-gest and most performing paper machines for the production of brown grades.
The paper machine is a Metso Optipress™ confi-guration, with a speed of 1900 m/min, desig-ned specifically for the production of Testliner/Wellenstoff from 60 to 125 g/m2 using 100% recycling. The production capacity is 650.000 Tonn/year.
The press section includes 2 shoe presses, with a max linear pressure of 1300kN/m. Felt width: 11.00 m.
Start-up clothing
In May 2009, Cristini Group was chosen as start-up supplier for both the press and dryer section.
The initial decision was to install endless fa-brics on both top positions, and seamed fabrics on bottom.
Since the start up, 67 press fabrics have been installed, showing excellent performances and seaming easiness (for the seamed versions).
After this stage it has been decided to run 100% endless fabrics, because of the fabric change efficiency reached by the mill crews.
The press fabric design
The press fabric design must satisfy extreme production requirement, because of the pro-duction speed and size. The water volume to dewater was an important challenge for the felt designers. The specifications forecasted a high dewatering in the 1st nip (75-80% of the total dewatering), and 20-25% on the 2nd nip.The water flows where designed as indicated in Fig.2
Fig. 1 – Press section layout Fig.2 – Water balance in the press section
papermiddleast 31
Because of the press geometry, the top felts where required to dewater mainly at the nip, while the bottom mainly at the suction boxes.
The designers choice was then oriented toward felts with mono-mono base, with high flow per-meability and easy cleaning, with a caliper able to develop, in combination with the batt layers, high compressibility thus high “nip dewatering”.
Press fabric compressibility is defined as the ra-tio in between the compressible part (normally batt and porous structures similar to fibers) and the incompressible part (traditionally the base fabric). If the ratio allows the compressible part to saturate hydraulically saturate also the incompressible one, the press fabric gains the most important characteristics of a “nip dewa-tering” design.
To obtain a correct compressibility ratio along the whole fabric life, a key role is played by the non-woven, porous structures like Komprex™, behaving like a fine base fabric, but having very high compression elasticity.
Combining these factors, the designer team was able to create for each position, a press fabric matching perfectly each single application require-ment.
A typical of DuraFlex™ design, optimized for each position, is composed by a structure indicated in Fig.3.By fine tuning the batt laye-ring and type of Komprex™ layer, it has been possible to differentiate the beha-vior of the top press fabrics (which require high nip dewatering capacity), from the bottom fabrics, which need to dewater at the suc-tion boxes. This difference in felt design takes under consideration the dewate-ring factors, but especially the machine run ability,
which impacts tremendously on its efficiency and productivity.
On the pick-up position it is essential that the fabric surface does not trig “sheet-stealing” phe-nomena, with consequent breaks in the size press.
In the bottom position it is capital to obtain a perfect planarity of the paper, not to trig sheet breaks in the 2nd press.The achievement of these results have been ob-tained with a “fine tuning” of the fabric struc-tures & porous layers months before the World record speed.
Fig. 3 – Structure of a DuraFlex™ press fabric
32 papermiddleast
Fig.4 Shows the void volume gradient of the 2 concepts. The change in the void volume distri-bution results into a better efficiency at the nip.
Examining some measurements taken on ma-chine, it is possible to evaluate the dewatering of the various positions, at the moment of the
world speed record, on April 14th, 2011. The press section, was dewatering, while producing 80gsm, an average of 5800-6000 l/min, an ex-ceptional result.
The dewatering ratio in between the 1st and 2nd
nip was 79% - 21%, in line with the design requirements.
Concluding, today’s know-how in press fabric design for high speed machines, allows a pre-cise prediction of the fabric performance in the different machine conditions.
This important factor permits the production of reliable and repeatable fabrics, which push ahead the limits, reaching higher levels of speed and efficiency.
Fig. 6 – Picture of the Paper Mill Team and the Cristini Group Engineers
Fig. 5 – Dewatering values during the World Speed record
Fig. 4 – Void volume gradient across the press fabric caliper
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Machine clothings
34 papermiddleast
Evolution improves dewatering in the press
In order to keep up with the competition, tis-sue manufacturers depend upon continuous improvements in performance of consu-
mables for their machines – such as fabrics and rolls. Energy consumption, machine efficiency and stable operation are just a few of the major concerns. All this is substantially influenced by the press fabrics, which play an important role in the production of tissue paper.
Therefore, as the first step in developing a new press fabric, Voith analyzed all the possibilities for the performance and structure of fabrics. Thanks to a new software program, it was possible to simulate the various physical conditions within the press sec-tion.
An investigation of the performance curve for conventional fabrics compared to the ideal capability of tissue fabrics revealed important behavioral characteristics with regard to energy consumption and life. The positive change in fabric porosity due to the compression forces and the flow of water through the fabric can also be observed here.
Polymers keep fabric density at an ideal value
Building on these new findings and insights, Voith Paper developed the Evolution press fa-bric. It combines existing technologies with a complex new process that adds special polymer particles to certain zones of the fabric (Fig. 1). The polymers are able to adjust the fabric den-
sity to an ideal value and keep it there. Outstan-ding dewatering characteristics are thus achie-ved in the nip. Consequently, starting up with new Evolution press fabrics requires almost no break-in time.
In order to be able to determine the most effi-cient use of the new material, Evolution was extensively tested in the Voith pilot tissue machine in Sao Paulo, Brazil. Various fabrics with different polymers were operated under identical conditions, so that differences in star-tup behavior could be observed. After several customer tests all over Europe, Evolution had undergone extensive testing under genuine pro-duction conditions. The feedback from tissue manufacturers was extremely positive.
Less drying energy and fewer Chemi-cals
Along with the advantages of improved dewa-
In the fall of 2010, Voith launched a high-performing press fabric for tissue ma-chines. Through the use of polymers, this press fabric provides for optimal nip dewatering over its entire life cycle.
Fig. 1: Three-dimensional fabric structure.
“For us, Evolution is clearly the best fabricthat we have ever run.”Jordi Goma Camps, Mill Manager at Goma Camps, Spain
papermiddleast 35
tering in the nip and quicker startup times, Evolution can reduce the thermal drying ener-gy required for the tissue web. It is kept at a low level over the entire life time of the fabric (Fig. 2). Running stability and performance are impressive. In addition, it was demonstrated in several tests under real production conditions that fewer chemical cleaning cycles were requi-red – in some cases they were even completely unnecessary.
The successes with Evolution so far are spring-boards for further developments. Voith Paper is currently working on expanding the test runs to other tissue machines. In addition, tests showed that Evolution in combination with the new So-larSoft polyurethane roll covers, which have a
special surface design, can achieve even better results.
Fig. 2: Energy consumption.
“We first tried Evolution fabric in our PM5. The performance was very good in terms of startup, energy savings, speed increase, flat profiles, stable runability and less chemical wash. Then we tried it in PM6, where we manufacture our DIP paper, and the perfor-mance was very similar, with better performance compared to the rest of the fabrics. Furthermore, usage of Evolution fabrics, have helped us to work towards the reduction of the paper carbon footprint, which is one of our main targets.”
Machine clothings
36 papermiddleast
Poorly maintained tension gauges may cause severe damages
Written by Mr. Marcel Lensvelt,Managing Director of Feltest Equipment BV -
Almost every paper mill using forming fabrics has one: a mechanical tension gauge to measures the tension of Paper
Machine Clothing, mostly forming fabrics. When these instruments are not in a perfect condition they can cause serious problems on the paper machine like torn fabrics, too narrow and/or too long fabrics and bearing failure.
Working principle
To understand the risks, it is important to unders-tand how the mechanical tension gauges work. In illustration 1 the working principle is shown.
The sensor bar at the bottom is pushed into the fabric by a predefined spring load. The amount of travel of the bar is converted through spindle and clockwork into a value on the dial. The higher the fabric tension, the more the bar is pushed upwards, causing the needle to rotate clockwise, indicating a higher value on the dial.
What happens when the devices get older?
After a certain period of use, the instrument will start showing signs of wear and tear. Mechanical wear of the sensor bar and a leaking bellow seal are the most common problems with older ten-sion gauges and exactly these two phenomena represent the highest risks.Worn sensor bar In many older tension gauges the sensor bar is worn down for several millimeters, resulting in a flat contact surface of the bar, like in illustration 2, compared to the original rounded bar.
Now remember the working principle of the gauge: in fact the travel of the sensor bar is converted into a tension value. In illustration 3, a worn bar is compared to a new bar. The spring load is equal in both cases, and also the fabric deformation will be practically the same with an
Illustration 1 - working principle of a mechanical tension gauge
Illustration 2 - example of a worn sensor bar
Illustration 3 - a worn bar compared to a new sensor bar
papermiddleast 37
old or worn sensor bar. But illustration 3 shows that the worn sensor bar will travel further downwards than its new counterpart.Leaking bellow seal The tension gauges are used in a very wet envi-ronment and the splash water can be quite corro-sive. Aging effects of the rubber material and the moving spindle will wear out the bellow, making it no longer watertight. When process water can enter the instruments interior, soon the bearings of the spindle will start corroding. This internal corrosion will give the spindle extra mechanical resistance during the measurement. In other words: with a certain amount of fabric tension the sensor bar will not travel as easy upwards as it should.
Conclusion: worn tension gauges give too low test results Summarized the two most common defects on mechanical tension gauges are a worn sensor bar and a leaking bellow, causing internal friction. Both defects have the same effect on the mea-surements: the gauge will show lower tension values than what they really are.
A worn sensor bar will move the spindle downwards and hence the needle moves coun-ter-clockwise towards lower values on the dial. More friction on the bearings makes the spindle ‘stick’ where it should be moving up; again re-sulting in lower values on the dial.
What happens in daily practice
In many paper mills the tension gauges are used
as long as the needle is still moving; the accuracy is often not questioned. For every Paper Machine Clothing position the operators know the desi-red fabric tension; for example 6 kN/m (see illus-tration 5). If the fabric tension is measured and the gauge shows 5 kN/m, the machine tension is increased until the gauge shows the desired 6 kN/m. The true fabric tension will then be clear-ly over the 6 kN/m mark.
Consequences of machine clothing running at too high tension
When the Paper Machine Clothing is running at a higher than expected tension a number of things can happen:
the fabrics may stretch, finally running out of tension possibilities; the fabrics can become narrow; the dewatering behavior of forming fabrics can change; the seam can be overloaded, resulting in torn fabrics; when the fabric guiding rolls cannot handle the extra tension, roll-bending or bearing failure may occur.
The negative effects of poorly maintained tension gauges are often underestimated. The conclu-sion of this article is clear: a regular service or timely replacement of this precision measuring instrument can prevent many costly problems and damages.
Illustration 4 - worn tension gauges give too low values
Illustration 4 - worn tension gauges give too low values
38 papermiddleast
The Egyptian Paper Industry two years after the revolution
It’s been two years since the January’s Revo-lution in Egypt. But the anger of the Egyp-tian people is still high and the process of
normalization will take some more time. The disorganization of the ruling power has affected the economic sector, including the paper indus-try, which is going up and down each time new events take place in the Egyptian streets.
From the beginning of the revolution on January 2011, the Egyptian paper mills suf-fered from the absence of police forces. As a consequence, most of the Egyptian and foreign paper companies working in the country expe-rienced difficulties in running their mills, facing problems such as transportation restrictions. Their supply of raw material being chaotic, they had to empty their stocks. At the same time, the distribution to customers was also problema-tic, causing a reduction of the production. In addition to that, they faced security threats andfears from the attacks from thugs and escaped prisoners.
Financial problems occurred as well with the lack of liquidity in the national economy. Sala-ries and suppliers could not be paid in time, as the banks had to cap the withdrawal and trans-fer capacities of their clients.Energy, a strategic aspect of the papermaking process, has also become a burden. Prices of natural gas have gone up drastically, and a shor-tage of diesel has led to a momentary closure for some mills.
On another front, the current foreign exchange rate does help either. The drop of the Egyp-tian pound against the US dollar might be in favor of national exports, but we should keep in mind that the paper industry is very dependent from imported raw material, equipment and spare parts. Although this problem has negative impacts on the industry, it also contains some positive ones. Prices of imported paper were raised as well, so paper traders turned to local productions. It proves that every problem goes with an opportunity.
Focus Egyptian Uptdate
From our correspondant in Egypt,Yasser Zakaria
papermiddleast #
The paper industry is cyclical. Every cycle takes 5 to 7 years. In 2003, the Egyptian paper indus-try entered a recession time due to the lack of raw material (waste paper) as a result of the start-up of 7 new mills in the country, creating a sudden rise in the demand.
Later on, the paper industry witnessed a period of growth and stability, but the curve downed
again in 2009 after the global economic crisis in 2008 which effects were showed clearly in Egypt in 2009. And after a new rise in 2011, the January’s revolution started and the recession happened again.
The best solution now to improve the situation is to encourage investment in Egypt with long term views. The unique position of the country within the Arab and Middle East region, and its proved capacity to constantly recover its eco-nomy is a real asset. Like in all emerging mar-kets, a brighter future in the paper industry can be foreseen, for those who start investing now. As it takes more than one year to implement projects, they would be ready at the best time of the cycle, at a moment when European mills will have severely reduced their capacities, and when consumers will be ready to consume again, for the good of the whole paper industry.
B-
B3
Evolution
Evolution
Voith Paper
Evolution SolarSoft
Evolution
Evolution
Voith
Evolution
Evolution
Jordi Goma Camps Evolution
Evolution
Voith Voith PaperEvolution
Voith
Evolution
Jordi Goma Camps
Goma
Camps
WISS
WISS
WISS
WISS
REFERENCES
1. DANBY, R., PERRAULT, J., “Weaves of Papermaking Wires and Forming Fabrics”, PAPTAC G18
Data Sheet (2003).
2. HENDER, B., “Efficiency Improvement Through the Use of Warp Exchange Technology”,
TAPPI/PIMA PaperCon’08 Conference, May 4-7 2008, Dallas, TX.
3. DANBY, R., JOHNSON, D., “Float Forming”, PAPTAC 92nd Annual Meeting 2006, C142 – C148.
4. IMNGMANSON, W.L., “An investigation of the Mechanism of Water Removal from Pulp Slurries”,
TAPPI 35(10):439-448 (1952).
5. IMNGMANSON, W.L., WHITNEY, R,P., “The Filtration Resistance of Pulp Slurries”, TAPPI
37(11):523-533 (1954).
6. HELLE, T., “The Influence of Wire Structure on Sheet Forming”, Paper Techn. and Ind. 21 (4), 12
(1980).
7. ADANUR, S., TIANYI, L., “3D Modelling of Textile Composite Preforms”, Composites Part B: Eng.
29(6): 787 (1998)
8. ADEBAR, T.K., “Imaging the Three-dimensional Structure of Forming Fabrics”, TAPPI JOURNAL
6(8):12-15 (2007)
9.HUANG, Z., OlLSON, J.A., KEREKES, R.J., GREEN, S.I., "Numerical Simulation of the Flow around
Rows of Cylinders", Computers and Fluids, vol. 35, no. 5, pp. 485-491, June 2006.
10. HERZIG, R., JOHNSON, D., “Investigation of Thin Fiber Mats Formed at High Velocity”, TAPPI
JOURNAL 82(1): 226-230 (1999).
11. JOHNSON, D., “Effects of Jet Impingement on Bel Baie Machines”, Pulp & Paper Canada
93(5):12, 14-15, (1992)
SSB-A SSB-B
WISS
SSB
WISS
Sample Air Perm (cfm)
Paper Side Properties FiberSupportIndex
DrainageIndex
Caliper(mm)Mesh x
KnockingMD yam (mm)
CD yam (mm)
Drainagearea (%)
WISS 490 63x59 0.2 0.18 29.4 120 28.7 0.99
SSB_A 490 63x54 0.2 0.19 30 114 26.5 1.25
SSB_B 520 63x60 0.2 0.18 29 122 31.2 1.04
WISS
WISS
. WISS
SSB
WISS
WISS
Greenhouse Packaging
SSB
SSB-A
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WISS
WISS
WISS
SSB
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WISS
WISS
SSB
SSB
SSIW .
SEM
SSB
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SSB
SSB
WISS SSB WISS SSB
WISS
SSBWISS
WISS
SSB
WISS
SSB
WISS
.SSB
M-2
M-2
Sample Sheet Basis Weight (g/m2)
0 4 12 19 27 38 53
SSB 8.0 12.7 34.4 55.9 91.9 142.1 222.0
Warp Tied 8.4 16.4 38.2 60.8 97.6 145.1 228.6
WISS 8.4 18.7 39.0 56.5 89.2 134.5 215.1
SSB
SSB
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SSB
SSB
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SSB WISS
Sample AirPerm(cfm)
Paper Side Properties FiberSupportIndex
Drai-nageIndex
Mesh x Knoc-king
MDyarn (mm)
CD yarn (mm)
Drai-nage
area (%)
SSB 370 94x90 0.13 0.13 29.1 180 33.3
Warp Tied
375 95x82 0.15 0.13 25.5 173 30.8
WISS 380 81x90 0.17 0.13 24.7 174 32.4
SSB
WISS
Gravity Sheet Former - GSF
GSF
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SSB
SSB
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WISS
WISS
SSB
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WISS
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