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Dear Customers, Dear Readers,

“By the way, congratulations on your new customer magazine – quite a source of information. But what else could we expect from the ‘twogether company’?”. This comment by a reputed customer in the USA reflects the overwhelming response to our first edition of “twogether” magazine. Not only the industry, but also professional associations, academic institutes and the trade journals were unanimous in this acclaim. Bearing in mind today’s flood of printed media and pressure of time, we were delighted with such a positive response. And it is nice to be called a “twogether company” – a sign of acceptance as partner in the paper industry. Hans Müller, President and CEO, Sulzer Papiertechnik GmbH Keeping you up to date in this way is another step in our strategy of closer customer contact. What are the next steps? How will the situation of papermakers and machinery manufacturers develop in the context of increasingly rapid global market changes? A dependable way of foretelling the future would certainly be the dream of all investors.

Some weeks ago we received an interesting paper on this theme by Riccardo E. Moeschlin, an expert not unknown in the paper industry. How valid are such forecasts? Since no recipe exists for reliable prognoses, and as human beings we are all prone to error, this theory based on repetitive economic cycles seems particularly interesting. Read on and judge for yourself!

One again, we trust that “twogether” No. 2 brings you interesting reading and some useful technical information.

Sincerely

Hans Müller 2 Aus dem Unternehmen 3 4

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2 Aus dem Unternehmen 5

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HIGHLIGHTS STARTUPS, ORDERS ON HAND

The tables below show main startups from October 1, 1994 to September 30, 1995 and prime orders on hand.

STARTUPS

Stock preparation AS Sunland Eker Paper Mills, Holmen Paper AB, Sweden Winding technology Sweden Haindl Paper GmbH, Schongau, - Duoreel Pope and Talbot, Wisconsin, USA Haindl Paper GmbH, Walsum, Waste paper processing systems Scott, Owensboro, USA MD Paper GmbH, Germany Germany and subsystems for and PWA Graphical GmbH, - Winders writings Waste paper processing systems Germany Tamil Nadu and Papers 945,000 tonnes p.a. and subsystems for other types of Albbruck Paper Mills, Ltd., Madras, India ANM Albury, Australia paper Germany Haindl Paper GmbH, Schongau, Stora Feldmühle, Langerbrugge, 110,000 tonnes p.a. Kanzan Spezialpapiere AG, Germany Belgium Germany Smurfit Newsprint Corp., USA Kemsley, UK Paper, Great Britain Utzenstorf Paper Mills, Smurfit Newsprint Co., USA Visy Paper, Australia Auburn VPS, USA Switzerland Stora Grycksbo AB, Sweden Visy Paper Conyers, USA Hann. Paper Mills, Alfeld, Germany Stora Langerbrugge N.V., Belgium Kostryznsie Zaklady Papierniecze Chemical processing systems Stora Feldmühle, Kabel, Germany Steinbeis Temming, Germany S.A., Poland MD Paper, Dachau, Germany MD Paper, Germany Norske Hönefoss, Norway Stora Billerud, Baienfurt, SCA Aylesford, Great Britain Stora Feldmühle, Hillegossen, Germany Georgia Pacific, Kalamazoo, USA Germany Finishing Weißenborn Paper Mills, Stora Forest Industries, Canada Germany Waste paper processing systems Supercalenders and subsystems for board and Coating technology Burgo Ardennes, Belgium packaging papers Paper machines Votorantim Celulose e Papel Simao PTS, Germany 550,000 tonnes p.a. Jacarei, Brazil Jiangnan , China 264,000 tonnes p.a. Kanzan Spezialpapiere GmbH, Visy Paper, Australia Germany Soft Lenk Paper Mills, Kappelrodeck, Printings and writings International Paper, Poland Henry Cooke Makin, Great Britain Germany Tamil Nadu Newsprint and Papers Consolidated Papers Inc., Biron Mill, Pap. de Gascogne, France Townsend & Hook Ltd, Snodland, Ltd, Madras, India USA NN, Germany Great Britain MD Paper, Germany Jang Chun, Korea P.T. Indah Kiat, Indonesia Board and packaging papers Albbruck Paper Mills, Georgia Pacific, USA Board AB, Fiskeby, Sweden Visy Paper, Australia Germany Portals, Great Britain Hansol Paper, South Korea Willamette Ind. Inc., USA Zaklady Celulozowa Papiernicze Shandong, China Shin Poong, South Korea Hansol Paper Co. Ltd, Korea S.A., Poland Hannover Paper, Germany Visy Paper, Conyers, USA Saica Zaragoza, Spain Pap. Calparsoro, Spain Rebuilds Ripasa S.A. Celulose e Papel, Longview Fibre, USA Waste paper processing systems Visy Paper Conyers, USA Limeira, S.P., Brazil Inland Empire Spokane, USA and subsystems for tissue papers Haindl Paper GmbH, Walsum, Kostryznsie Zaklady Papierniecze Visy Board, Australia 148,000 tonnes p.a. Germany S.A., Poland Tai Shan, China Thrace, Greece Cartiere Burgo SpA, Italy Scheufelen Paper Mills, Zhu Hai, China Apizaco, Mexico Stora Billerud GmbH, Germany Germany Sappi Specialities, Great Britain 7

Papelera De Castilla Duenas, Spain Machine calenders Weyerhaeuser, USA Roll transport systems Sam Poong, Korea Crown Packaging, Canada Bruckmann, Germany Suzano, Brazil Australian Paper Botany Mill, Rebuilds Maul Belser, Germany Perlen paper Mills, Switzerland Australia Arjo Wiggins, France Burgo Ardennes, Belgium SNIA f. Krasnokamsk, Russia Zhu Hai, China Koehler, Germany KNP Leykam, Netherlands Long You Paper, China Crane Byron Mill, USA Pudumjee, India

ORDERS ON HAND

Stock preparation St. Petersburg Combine, CIS Tien Long Paper Mill, Taiwan Companhia Suzano de Papel e Corenso United Ltd, Finland Industria Cartaria Tronchetti Burgo Celulose, Brazil a Mozzano, Italy International Tendering Company Waste paper processing systems Chemical pulp processing systems CNTIC, China and subsystems for printings and 597,000 tonnes p.a. Rebuilds writings Visy Paper, Australia 1,466,000 tonnes p.a. Neidenfels/Blue Star, Bataan Pulp and Paper Mills Inc., Finishing Germany/China Hermes Paper Mills, Germany Philippines Tronchetti, Italy B.V, Netherlands CMPC, Santiago, Chile Supercalenders Hiang Seng, Thailand Trust International Paper Corp., Thomas Tait & Sons Ltd, KNP Leykam, Netherlands Philippines Great Britain Yuen Foong Yu, Taiwan Pulper feed systems Holmen Paper Mill, Braviken, Tentok paper Co. Ltd, Japan Bosso, Italy Stora Feldmühle, Belgium Sweden Davidson & Sons, Great Britain UPM Tervasaari, Finland VPK Oudegem, Belgium Australian Newsprint Mills, United Paper Mills Ltd, Finland Marubeni for Daishowa, Japan Ningbo Zhonghua Paper, China Australia Federal Co., USA Hansol Paper, Korea St. Petersburg Carton Combine, Jiangmen, China Consolidated Paper Inc., USA CIS Stora Kabel GmbH, Germany Rigesa Celulose, Papel e Soft calenders Corenso United Ltd, Finland Paper Industries Corp., Philippines Embalagens Ltda, Brazil Genting Newsprint, Malaysia Halla Engineering & Heavy Assidoman Kraftliner, Sweden CMPC Procart, Chile Industries Ltd, South Korea Paper machines Westvaco Corporation, USA Ballarshah, India Hansol Paper Co. Ltd, South Korea Stone Container Corporation, USA Siam Paper, Thailand Georgia Pacific, USA 3,198,000 tonnes p.a. Pap. del Aralar, Spain Dae Han Paper, South Korea Coating technology Miliani f., Hungary Genting Newsprint Sdn. Bhd., Printings and writings Nippon Paper, Japan Assi Domän, Sweden Malaysia Consolidated Papers, Stevens Point, Koehler Paper Mills GmbH, Kymmene Wisaforest, Finland USA Germany Simao, Brazil Waste paper processing systems Holmen Paper Mill, Braviken, Federal Paperboard Comp. Inc., Henry Cooke Makin, and subsystems for board and Sweden USA Great Britain packaging papers SCA Ortviken AB, Sweden SCA Ortviken AB, Sweden IP Kwidzyn, Poland 2,479,000 tonnes p.a. Sinar Mas Pulp & Paper Ltd, India Hansol Paper Co. Ltd, Korea J.R. Crompton, Great Britain Ningbo Zhonghua Paper, China Halla Paper Co. Ltd, Korea Halla Paper Co. Ltd, Korea Portals, Great Britain CMPC Procart, Chile Mazandaran Wood and Paper Hong Won Paper, Korea Ningbo PM 3, China Zülpich Paper GmbH & Co. KG, Industries, Iran Consolidated Paper Inc. Stevens Ningbo PM 2, China Germany Point, USA Halla Paper, Korea SCA De Hoop, Netherlands Board and packaging papers Kymi Paper Mill, Finland Holmen Paper, Braviken Mill, VSDN Cape Kraft, South Africa Visy Paper, USA Sweden Cheng Loong Co. Ltd., Taiwan Zülpich Paper GmbH & Co. KG, Winding technology SCA Ortviken, Sweden Thai Industries Co. Ltd., Germany - Duoreel Thailand Victorgo Industries Guangzhou, SCA Ortviken AB, Sweden Machine calenders Georgia Pacific, USA China Koehler Paper Mills GmbH, Australian Paper, Australia Port Townsend, USA VPK Oudegem, Belgium Germany Ningbo, China PT Indah Kiat, Indonesia Ningbo Zhonghua Paper Co. Ltd, Holmen Paper AB, Sweden Townsend & Hook Ltd, China Industria de Papel Arapoti SA, Great Britain Waste paper processing systems Thai Kraft Paper Industry Co. Ltd, Brazil Crown Packaging, Canada and subsystems for tissue papers Thailand - Winders SCA Ortviken, Sweden 93,000 tonnes p.a. Visy Paper, Brisbane, Australia Halla Engineering & Heavy Mazandaran Wood and Paper Industries Ltd, Korea Rebuilds A/S Sunland Eker/Papirfabrikken, Industries, Iran Papeles Bio Bio SA, Chile Stora Kabel, Germany Norway P.T. Indah Kiat, Pulp & Paper Corp., Holmen Paper AB, Sweden Stora Reisholz, Germany Crisoba Industrial, Mexico Indonesia Genting Newsprint Sdn. Bhd., Cart. Toscolano, Italy CMPC-Cia. Manufacturera de Malaysia Waste paper processing systems Papeles y Cartones S.A., Chile Fabricadora de Papel de Celulose Roll transport systems and subsystems for other types of S.A., Brazil KNP Leykam, Netherlands paper Tissue Townsend & Hook Ltd, Scheufelen Paper Mills, Germany 478,000 tonnes p.a. Bacraft, Brazil Great Britain NDI, Netherlands Australian Paper Manufacturers, Al Keena Hygienic Papermill Co. Ltd, Guangzhou Victorgo Industries Co. Halla Paper, Korea Fairfield Mill, Australia Jordan Ltd, China Genting Newsprint, Malaysia 8

NEW PLANTS AND SYSTEMS

Stock Preparation Division: The first waste line at MD Papier GmbH, Plattling

This recycling line with its trend-setting and publishers which was agreed in waste paper) as well as higher-grade technology recently went into service autumn 1994. Primary design criteria for standard furnish such as waste, after more than two years of fruitful col- this recycling line were environmental returns and department store catalogues. laboration with MD Papier GmbH. To compatibility and consistently high prod- meet specific requirements, convention- uct quality. Thanks to completely new Depending on processing mode (special al recycling technologies were further technological developments, it is now or standard grade waste paper), the cor- developed and adapted accordingly. possible for the first time to use old rect machine sequence can be run Capacity of the new Plattling recycling labels from reutilized beer and beverage accordingly. The goal of this line concept line is 72,000 t.p.a. of waste paper bottles as furnish for making high grade was dual utilization of as many aggre- furnish. Design services and machinery printing papers. This is done by efficient were supplied by a consortium mainly removal of , and wet- Stock processing line flow diagram comprising Voith Sulzer Stock Prepara- strength additives. for standard waste paper tion GmbH, , B+G Förder-

technik GmbH, Euskirchen, and Maschi- Previously, old labels of this kind were Raw materials treatment nenfabrik Andritz, Graz/Austria. disposed of in landfills or used as filler material in the tile and brick industry, Pulping MD Papier GmbH thus wasting the high-grade kraft pulp of HC cleaning has invested 53 which they were made. million DM here in Hole screening a recycling line The so-called eco-agreement signed by with almost en- MD Papier together with several brewer- Flotation tirely closed-cir- ies creates the logistical conditions LC cleaning cuit water loop required for label recycling. As a result, layout. This repre- some 60,000 tonnes of bottle labels cir- Slot screening sents a significant culating every year in Germany can now contribution be used as furnish for high grade pro- Thickening toward increasing ducts. Disperging the waste paper recycling quota in The new recycling line – the first of its Bleaching Germany, a self- kind – makes this technically feasible by imposed obligation allowing the use of high wet-strength Wet lap unit Storage of paper producers labels and punchings (special-grade 1 Stock Preparation 9

, PRODUCT DEVELOPMENTS

Fig. 1: Stock processing line flow diagram for standard waste paper.

Fig. 2: Waste paper charging system with automated bale dewiring, designed and built by B+G Fördertechnik GmbH, Euskirchen, an associated company of Voith Sulzer Paper Technology Group.

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gates as possible in both modes. Daily conveyor automatically as soon as a pre- The pulper is drained via a PreClean capacity is up to 220 tonnes of waste determined waste paper charge has been system, which minimizes dumping time paper. fed to the pulper. while at the same time ensuring consist- ent mixing of dilution water during dumping. It also ensures efficient junk Raw materials handling Pulping and HC cleaning removal. Waste paper is delivered loose or in The waste paper is pulped at a stock con- bales. The bales are automatically sistency of 15-17% in an intermittent The 2-stage PreClean system comprises a dewired with a B+G Fördertechnik high-consistency pulper. This is designed Fiberizer with special rotor/screen combi- machine, and fall as loose material on the for maximum fibre retention and efficient nation, a buffer tank and drum screen. slat conveyor pulper feed belt supplied by deinking. Coarse rejects are removed at an early the same company. stage by the Fiberizer hole-screen plate. All deinking additives are fed to the pulp- Any fibres contained in the coarse rejects The integral weighing system stops the er together with each charge. are recovered in the drum screen before 10

Fig. 3: Hole screening in the Fibersorter.

Fig. 4: Compact flotation cell. they are dewatered and compacted in the rejects screw press.

The pulp is pumped into one of three 200m3 dumping towers in order to ensure adequate fibre swelling and chemical reaction of the deinking additives. Pulp leaving the dumping tower then passes through a high-consistency cleaner.

Hole-screening Basic principle of the 3-stage hole- screening system is early removal of screenable rejects, with systematic for- ward feed of accepts.

The first and second screening stages comprise two Omnisorters for standard waste paper, or two Fibersorters for spe- cial-grade WP. Coarse rejects are 3 removed in the third stage, which com- prises a Rejectsorter.

Flotation In the flotation stage all the particles and finely disperged impurities are removed. This gives a consistently high quality recycled product which meets all requirements for manufacturing printing papers.

The flotation aggregate comprises five primary deinking cells and one secondary cell. These closed-circuit cells are arranged in pairs, one above the other. Flotation air is injected into the stock suspension through independently oper- ating step diffusors. Thanks to the high air content (up to 60%) and wide bubble spectrum, all ink particles from 10 to 500 µm in size are removed. The closed-loop 4 Stock Preparation 11

Fig. 5: Stock thickening in the double wire press.

Fig. 6: Disperger with heating screw. flotation air circuit prevents polution of the atmosphere.

In the secondary cell any fibres still usable are recovered. The sludge remain- ing is dewatered as far as possible in the prescreener before treatment in the sludge handling unit (supplied by Maschinenfabrik Andritz).

Low consistency cleaning and slotted screening The small heavies, sand and plastic parti- cles are removed in a 4-stage heavies cleaner.

Rejects are treated with the sludge, while the accepts are processed for light weight contrary removal. 5 In a 3-stage slotted screen system the suspension is fine-screened again to remove mainly all the cubic rejects and stickies.

Thickening, disperging and bleaching The clean suspension is now passed through a disk filter and afterwards dewatered in a double wire press (supplied by Maschinenfabrik Andritz). This thickened stock is then conveyed by a screw system comprising shredder, elevator, feed and steam-heating screws to a disperger with cast fillings. The dis- perging effect is based on the principle of intensive friction between fibres. This homogenizes the stock and drastically reduces visible dirt specks. In order to increase brightness, the stock is processed in a bleaching disperger with reductive additives. 6 12

Fig. 7: Washing in the VarioSplit.

Fig. 8: View of storage tower.

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Washing and wet lap system returned to the stock preparation process For processing special-grade waste paper water loop. The VarioSplit filtrate is like- furnish, the stock is washed in a Vario wise cleaned by microflotation. Split after low consistency slotted screening. It is then processed in a wet lap unit and paletted ready for dispatch. Rejects compacting Coarse rejects from the PreClean dump- ing system and hole screening are dewa- Storage tered and compacted in a rejects screw After medium consistency bleach dis- press. perging, standard waste paper stock is pumped to a storage tower. Rejects from the high and low consisten- cy cleaners are transported by container for landfill disposal together with com- Water loops pacted rejects from the screw press. The water loops in this stock preparation line are almost entirely closed-circuit. Except for added dilution water and sealing water, no fresh water is used. The sludge dewatering filtrates are purified by microflotation in a Purgomat, and Stock Preparation 13

Fig. 9: Water purification by Purgomat.

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Stock Preparation Division: The C-bar screen basket – a high-tech product

According to an old saying: “paper is ing process as a whole – in other words (Fig. 2). These were generally ≥0.8 mm made in the Holländer”. Despite the com- what goes into the at one wide, but for special applications slots as mon opinion that paper mills only contain end, and how it is processed after it small as 0.45 mm were used. paper machines, this still holds true – as reaches the other end. long as “Holländer” is replaced with “stock preparation”. The limits of slotted screens were dictat- Screening machines today generally ed by manufacturing processes, which The task of stock preparation – the operate under pressure, and the pulp has allowed a relatively small amount of free “factory” feeding to be pumped into them (see Fig. 1). screening area, and by the low rotor effi- the paper machine Inside the screen housing is a rotor and ciency due to the smooth surface. Both – is to process a fixed cylindrical screen basket. This these factors reduced throughput, so that basic is perforated either with holes or with slotted screens were relatively uneco- materials accord- slots. nomical. ing to the required product grade and quality. Screening Whether the screen basket has holes During the second half of the seventies, has always been or slots depends on the kind of rejects papermakers called more and more for an important part to be removed. The rule of thumb here greater use of slotted screens and at the of stock prepara- is to use holes for flat materials (such same time for smaller slots. Screen man- tion, and since the as foils) and a slotted screen for cubic ufacturing methods at that time did not rise of waste paper particles (e.g. styropor). The idea is that allow either for modifying screen flow as a basic materi- the stock fibres should pass through conditions or for increasing the free al, it has become the screen and the unwanted materials screening area. The only possibility The author: R. Rienecker, even more impor- should remain for subsequent removal. remaining was to increase turbulence, Product Group tant. and hence throughput, by adding bars to Screening the rotor side of the screener basket. It is easy to see that apart from other With traditional primary furnish such as parameters, the main aspect here is the groundwood and chemical pulp, the com- size of screen hole or slot. As a further development of these high- ponents to be screened largely comprise turbulence screener baskets, a wide solid particles such as splinters. With variety of surface profiles were proposed. greater use of recycled paper, the main To meet today’s demands for clean stock One example is the so-called VV basket requirement now is to remove softer despite more use of dirty waste paper, (Fig. 4), comprising a large number of components such as stickies, foils, sty- very small screen holes or slots have to “minibars” generated by milled grooves ropor and other rejects. This is much be used – and the trend is more and in the basket surface. The principle here more difficult than screening out solid more toward fine slots. was that the depth of these grooves influ- particles. ences screening efficiency to a certain extent. In simple terms, a very rough sur- Slotted screens are nothing new, but ever face increases throughput, while a The main importance of screening tech- since the screen was invented they smoother surface increases screening nology lies not so much in the finished have played a secondary role. Slotted efficiency. paper quality, but in the cost-effective- screens in the past comprised flat plates ness of the paper production and finish- in which slots were cut painstakingly All these screener basket versions had Stock Preparation 15

Fig. 1: Schematic arrangement of a screen: 1 housing, 2 screen basket, 3 rotor, 4 bearings, 5 drive.

Figs 2, 3, 4: Slotted screen basket patterns.

three drawbacks in common, however: the relatively small free screen area due to manufacturing restrictions, the poor inlet 1 flow characteristics due to sharp slot edges, and last but not least the high manufacturing cost.

Back in the nineteen-seventies Voith therefore started developing smooth or bar 5 type screener baskets, for which several 2 patents were taken out (see Fig. 5). This development represented a quantum leap 3 in screening technology at that time. 4

These baskets no longer had milled slots with milled surfacing. Instead they have profile bars with an approximately trian- accepts gular cross-section, spot-welded to strips which later form the stiffening rings on rejects the finished basket.

1 The slot width is defined by the bar spac- ing, while the bar angle generates the surface profile. These flat screens are then rolled into cylindrical form and welded together into a finished screen basket.

In many respects these screen baskets are far superior to their machined prede- cessors. This superiority can be summar- ized as follows:

smooth bar type VV type I Higher screening efficiency for the same slot width I No sharp edges I Large free screening area 2 34 I Lower screening energy consumption 16

Fig. 5: Principle of the conventional bar-type basket.

Fig. 6: Principle of the C-bar screen basket.

a plain and simple product. Direction of rotor rotation Direction View A In order to comply with flow patterns, of rotor a screen basket is a highly filigrane A rotation structure. On the other hand it has to withstand extremely high dynamic loads for long periods in the screening ma- chine, and is often exposed to abrasive attack as well.

By its very nature, the basket has a very large number of interconnecting points, which from the stress point of view have 5 the same effect as notches.

Direction of rotor rotation Direction View A of rotor On top of this, the use of chrome-nickel A rotation stainless steel turns the development of such a screener basket into an engineer- ing challenge of the first magnitude.

The manufacturing process involves the following main steps:

I Precise cutting of the clamping profile 6 in the bars by laser technique I Low-cost manufacturing eliminated by developing and patenting I Production of a flat screen by fitting These fabricated screen baskets also have an innovative manufacturing process. specially drawn profiled bars on a their manufacturing limits, however: newly developed welding machine I Rolling the flat screen into a cylinder All problems were solved through close and welding the ring ends together I Relatively wide scatter in slot width cooperation between manufacturing spe- I Machining the end flange and welding I Smallest slot size limited to about cialists and stock preparation experts, it to the cylindrical screen 0.2 mm since narrower slots require and the result is a mature screen basket I Finish-machining the entire screen thinner bars and reduce basket meeting all market requirements. basket. stability.

It is not easy for the layman to imagine Each of these manufacturing steps – par- While retaining the bar-screen principle, how many problems were involved in ticularly welding and rolling – not only these deficiencies were then completely developing what seems at first sight to be demands precise work planning but high- Stock Preparation 17

Figs. 7 and 8: Slot width scatter of the C-bar screen basket compared with a conventional bar-type basket. The patented C-bar basket manufacturing technology guarantees width tolerances below 0.01 mm for 80% of slots.

ly trained machinists. The final result of all these trials is the C-bar screen basket – a high-precision product which is almost a work of art. Fig. 7 shows the slot width scatter of the C-bar basket. Our patented manufactur- ing technololgy guarantees that 80% of the slots deviate in width only by ≤0.01 mm and the other 20% by ≤0.02 mm. In most cases the measured scatter is sig- nificantly less (Fig. 8).

The problem of weld faults at the connec- tions between profile bars and stiffening rings does not apply to the C-bar manu- facturing process, because the bars are clamped into the rings and not welded.

The advantages of the C-bar screener basket, in the meantime patented world- wide, are listed follows:

I Bar-type basket without welding points in the screen structure I Rings and bars shaped to clamp 8

together es is shown by the fact that within a 80% I Extremely close slot width tolerances short space of time about 700 C-bar 70% I High uniformity and stability of slots in screen baskets of various sizes (see C - bar-basket the longitudinal direction due to close- Fig. 10) are now in service worldwide. 60% ly spaced stiffening rings And this trend is growing, since at the 50% I High surface quality (cold-drawn bars present time 6 fine screens in deinking

40% without welding) plants are entirely equipped with 0.15 Conv. bar-type I 0.1 mm slot width easily reproducible mm C-bar baskets, all with excellent 30% I Large free screening area results in stickies removal. 20% I Optimally variable profiling (no manu- facturing limits). 10% Equally successful is the installation of 0 a 0.15 mm C-bar screen basket in the ≥ 0,15 0,2 0,25 0,3 ≥0,35 mm 7 Customer appreciation of these advantag- approach flow section of a photographic 18 Stock Preparation

Fig. 9: Macro-view of the C-bar screen basket.

Fig. 10: Nothing succeeds like success: more than 700 C-bar baskets in various sizes have gone into service in a short space of time.

An important point is that in many cases from the design point of view and with existing screens cannot simply be regard to manufacturing. By entering this upgraded with C-bar baskets. The operat- high-tech field at an early date, Voith ing parameters have to be taken into con- Sulzer has acquired not only considerable sideration as well as the kind of screen know-how in manufacturing C-bar bas- and the system layout, etc. Above all kets, but also wide background knowl- when extremely fine slots are required, edge on their applications in the paper screen and system behaviour deviates industry. This allows fast reaction to new from experience with previous basket demands. types.

C-bar baskets are currently in service for 9 LC screening on waste paper stock pre- paration lines, for screening woody pulp paper machine – a particularly demand- and in approach-flow screening systems. ing application. Likewise 0.1 mm C-bar They are soon to be used for medium baskets are now in service successfully, consistency screening, and trials are for example in an American waste paper already underway. stock preparation line and in an SC paper mill, where the extremely fine slots and suitable profiling has brought unsur- New applications and the associated passed splinter removal efficiency. problems demand continuous develop- ment work on the C-bar basket, both

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Stock Preparation Division: The EcoCell, an example of synergy effects in flotation cell development

The new EcoCell combines the advantag- Close comparison of the two types with papers (/magazines) due to es of both existing Voith-Sulzer flotation regard to technology, design and operat- its design advantages in this respect, cells – the E-cell and the Compact Flota- ing principle brought the following find- while for difficult waste papers such as tion cell. These comprise on one hand the ings: laser and multiprint, the more complex design features of the E-cell (simple technology of the CF-cell was justifiable control strategy, practically unlimited The design advantages of the E-cell lie in because of its technological benefits. scale-up and inside aeration element), the cell unit and periphery (Fig. 1): and on the other the technological bene- fits of the CF-cell (excellent efficiency in I Uncomplicated scale-up on a linear The next step was obviously to try and reducing a wide ink particle size range). basis combine the advantages of both types. A I No scale-up limitations (except pos- valuable basis for this was the thorough This has been sible pumping limits) research work carried out by Sulzer achieved by apply- I Simple level control by compensation Papertec on further development of the ing the CF-cell between cells, i.e. only one level con- compact flotation cell. It was found that aeration principle trol loop per stage greater efficiency particularly in dirt to the E-cell aera- I Interior aeration element, particularly speck removal could be reached mainly tion element. Initial advantageous with closed-circuit pro- by modifying the hydraulics of the air tests on a pilot cess air loops. injection element. plant have confir- med the outstand- ing efficiency of the On the other hand, the CF-cell also has In this way the principle of the CF aera- new Voith Sulzer technological advantages due to its more tion element was transferred to the EcoCell, and these sophisticated injector design (Fig. 3). mixing-bundle injector of the E-Cell. will now be fol- This results in an excellent efficiency in None of the existing design advantages of lowed by opera- reducing a wide ink particle size range, the E-cell were lost in this connection, in tional trials in a particularly including large dirt specks. fact they were improved. The air suction paper mill. hole of the E-cell injector was replaced by intake slots leaving almost the entire Comparative testing on the Ravensburg injector periphery free, thus reducing the pilot plant showed that for relatively easi- possibility of air intake blockage. After Sulzer Paper- ly deinked waste papers (newspapers/ tec and Voith magazines), both types of cell give equal- joined forces in ly good technological results in their As shown in Fig. 5, the comparative tests paper technology, standard layouts. carried out on the new aeration element one question was, prove the technological superiority of the which type of flo- EcoCell both for easily deinked waste tation cell should For waste papers which are difficult to papers (newspapers/magazines) and dif- be followed up as deink, such as mixed office waste, laser- ficult grades such as laser and multiprint. The authors: a joint Voith-Sul- print and multiprint, the CF-cell removes T. Martin and H. Britz, zer product – the large ink particles (200-400 µm) consid- product group E-cell or the Com- erably better than the E-cell (see Fig. 4). As a next step, these positive results will Flotation pact Flotation cell Based on these findings, it was decided be confirmed by practical trials on a flo- (see Figs. 1 and 2). to use the E-cell for easily deinked waste tation unit. 20 Stock Preparation

Fig. 1: Fig. 4: Principle design of the Voith Sulzer E-cell. Comparison of E-cell and CF-cell: test results. Fig. 2: Principle design of the Voith Sulzer Fig. 5: Compact Flotation cell (CF). Technological comparison between the E-cell with mix-bundle injector and Fig. 3: the EcoCell with new injector design. Design of the aeration element of the Voith Sulzer CF-cell.

With the EcoCell, a flotation cell will be available in future which optimally com- Inlet bines the advantages of both existing types. Process Air

Apart from further tests on the EcoCell, Foam upgrading kits are being developed at the present time which will enable existing Accept flotation units of (…) to benefit from the new aeration technique (multi-injector tube cells or E-cells).

1

66 100 Max. flotability limit 64 80 Inlet 62 60 60 3-stage air 58 Air aeration Brightness [% ISO] 40 element 56 54 50% newspapers 50% laserprint, 50% magazines 20 50% multiprint 52 Stock consistency 1.1% Stock consistency 1.1%, 4 cells

50 Reduction in Dirt speck area [%] 0 Accept 0123456 0 100 200 300 400 Foam Number of cells Particle size [µm] Both cells with CFC cell E cell standard aeration elements 2 4

62 100 Stock Max. flotability limit 60 Process air 80 58 60 56

Brightness [% ISO] 40 Step diffusor 54 50% newspapers 50% laserprint 52 50% magazines 20 50% multiprint consistency 1,1% Stock consistency 1.1%, 4 cells

50 Reduction in Dirt speck area [%] 0 Impack mixer 0123456 0 100 200 300 400 Distri- Number of cells Particle size [µm] bution E cell EcoCell diffusor mixing-bundle injector new aeration element 3 5 21

Paper Machines Division: NipcoFlex shoe press – the new product symbiosis

In 1984 the world's first closed shoe lubricating oil distribution pipe spreads press went into service: the Voith Flexo- 80 cool oil uniformly over the sleeve imme- nip press. Two years later followed the 70 diately after the press nip, thus ensuring Sulzer Escher Wyss equivalent: the Inten- freedom from wear. An added benefit of 60 sa-S shoe press. Thanks to their high this single-source system is the above- efficiency and outstanding technological 50 average life of the yarn reinforced Quali- results, both systems soon became well- 40 Flex press sleeves, a patented product of established (see Fig. 1). A total of 30 Voith Sulzer Paper Technology. 26 Flexonip and 28 Intensa presses are now in operation, mainly for brown 20 As shown in Fig. 4, the shoe generates a paper and paper- 10 pressure profile with three characteristic

board production. Number of installations 0 zones. In zone 1 the pressure rise is rela- Since Voith Sulzer 1985 1988 1991 1994 1997 tively steep until the beginning of the Paper Technology 1 dewatering phase (zone 2), during which was founded, orders have been Flexonip Presse Nipco-Intensa-S-Presse NipcoFlex-Presse booked for another 15 Flexonip and Intensa shoe presses.

The joint venture between Voith and The author: Sulzer in paper W. Schuwerk, technology has NipcoFlex Technology brought a symbio- sis of the best products from both sides. Based on more 2 than 200 years of accumulated operating experience with closed shoe presses, the press with the pressing system of the pressure rises more gradually to ensure greater patent freedom now applying has Intensa press. Pressed against the roll by uniform compacting. In zone 3 the pres- been exploited to unite the advantages of individual elements, the shoe is made up sure falls off steeply to prevent rewetting. both concepts in a single product: the of an top and a bottom part which are This kind of pressure characteristic is NipcoFlex press. This symbiosis is not thermally insulated from each other. As a indispensable for gentle dewatering and a limited to the roll and shoe alone, but result, thermal deformations are largely uniform sheet structure with greatest also includes the backup roll – in other avoided. The shoe is asymmetrical to the possible volume retention. Apart from words, the entire press system (see pressing direction, displaced toward the this, pressure profiles with moderate gra- Fig. 2). Since the market launching of ingoing nip. The flexible roll sleeve is dients and low maxima also give longer this concept, ten NipcoFlex presses have likewise asymmetrical to the pressing felt and sleeve life. already been sold. direction, thus allowing a more favour- able sleeve intake geometry. Lubrication As backup to the NipcoFlex roll, the The new NipcoFlex roll shown in Fig. 3 between the press shoe and roll sleeve is Nipco-P roll shown schematically in combines the shoe design of the Flexonip purely hydrodynamic. To this purpose a Fig. 5 combines the advantages of the 22

Fig. 3: Cross-section through an inverted NipcoFlex roll: 1. Support structure, 2. Sleeve guides, 3. Press roll sleeve, 4. Lubricating and cooling oil, 5. Oil return, 6. Hydrostatic oil, 7. Lubricating oil distributor, 8. Pressing element, 9. Press shoe.

Fig. 4: Ideal pressure profile. Fig. 1: ( 21) Sales development of Voith and Sulzer Fig. 5: shoe presses. Longitudinal section through a Nipco-P roll: 1. Bearing housing, 2. Roll sleeve, Fig. 2: (page 21) 3. Support structure, 4. Pressure oil, The symbiosis of Voith Sulzer shoe presses. 5. Pressing element, 6. Oil return, 7. Drive.

classical Nipco roll with the stable bear- is enormous potential for improving ing positioning of the profile roll. In fact I II III dry content, output and product quality. the designation Nipco-P stands for “posi- By using a shoe press instead of a tion-stable”. The roll bearings are spaced conventional third press, dry content was directly opposite the main roll bearings, increased by 5% to 49-50% – despite a and therefore unaffected by the inevitable 200 m/min speed rise to nearly 1200 beam deflection. This brings some pressure m/min – thanks to the sixfold increase in important advantages with regard to line force (see Fig. 8). This brought a Time press operation. According to the well- productivity rise of more than 16% with- proven Nipco principle, the roll shell Zone l: Relatively steep pressure rise out any reduction in specific volume, until dewatering run on internal hydrostatic support Zone ll: Flatter pressure rise during which was even increased slightly. Sheet elements. As shown in Fig. 6, these dewatering smoothness and 2-sided uniformity after operate on identical bearing surface areas Zone lll: Steep pressure fall to prevent soft calendering were improved at the rewetting in both rolls and are supplied with 4 same time. The technological results and hydrostatic oil from a common feed pipe. This allows extremely simple and reliable control, only one valve being required, and neither the roll bearings nor roll shell can be damaged under any circum- stances. Only at the edges are small compensation elements required for pressure relief in case the web width is changed.

One of the main reasons for the versatil- ity of the NipcoFlex press is its compact bearing frames (see Fig. 7). Thanks to patented link elements, mechanical forc- 1234567 5

es are transmitted directly from roll to cost-effectiveness of this concept have roll without the need for massive sup- complied with all expectations. ports. This allows simple press design 1 with good accessibility, as well as fast For extremely high operating speeds, 2 felt and sleeve changing. shoe press concepts with closed-loop 3 web runs are available. In mid-1996 the 4 So far shoe presses have mainly been world’s first 4-roll press with integral 5 used on paperboard and packaging paper shoe press in the third nip is due to go 6 machines, and only now are they coming on line in a 9.6 m wide newsprint 7 into use for manufacturing wood contain- machine operating at 1800 m/min. Com- 8 ing and wood-free printing papers. pared with existing concepts, the design 9 Operating experience with the world’s of this Duo-Zentri NipcoFlex press (see first shoe press on a newsprint machine Fig. 9) represents a real quantum jump. 3 has shown that in this field as well, there With dry content reaching 48% or more Paper Machines 23

Fig. 6: Pressurizing system of a NipcoFlex press.

Fig. 7: Mechanical force transmission: Conventional shoe press (left) Compact NipcoFlex press (right).

immediately after the press at an operat- Nipco-P roll ing speed of 1700 m/min, and a basis weight of 42 g/m2, productivity expecta- Pressure in tions on this machine are high indeed. P I hydrostatic Another decisive advantage over conven- elements tional 4-roll presses is of course the high volume retention during dewatering in the last nip.

Before shoe presses come into general End zone relief use for wood-free writing and printing A X B papers, a good deal of testing and oper- ating experience is still required. The NipcoFlex roll P T trend is clear, however: not only do shoe presses bring the decisive advantages of System P I higher dry content and greater productiv- pressure ity, but in particular they also improve product quality. For these reasons shoe M presses will soon be state-of-the-art for printing and writing papers as well as 6 board and packaging products.

7 24 Paper Machines

Fig. 8: Technological results after conversion to NipcoFlex (Perlen No. 5 newsprint machine).

Fig. 9: Example of a Duo-Zentri NipcoFlex press.

Before rebuild After rebuild Dry content 960 m/min 1060 m/min

Newsprint 43 g/m2

55 49% 50 45 44% 40 35 Dry content [%]

Before rebuild After rebuild

Specific volume PPS roughness Oil adsorption (COPB)

Newsprint 40 g/m2 Newsprint 40 g/m2 Newsprint 43 g/m2 ] 2

3.0 4.0 [g/m 30 /g] 3 m]

µ After 2.0 3.5 3.4 20 18.3 17.2 1.67 1.68 3.3 calendering 15.6 15.7 3.1 3.1 1.0 3.0 10

TSRS TS RS TSRS TS RS Specific volume [cm Oil adsorption (COPB) PPS roughness [

Before rebuild After rebuild Before rebuild After rebuild Before rebuild After rebuild 8

9 25

Paper Machines Division: Top DuoRun – a new dryer concept for high-speed paper machines

Summary tent in the paper. In the V-Top DuoRun, the damp web in the open draw of the Machine operating speeds at the present the dryer section is arranged as a single double-tier dryer group. The dryer section time for producing printing paper are just line in vee-form, thus shortening it by of paper machine 11 in the Schwedt mills over 1500 m/min on average, and new about 20%. (Fig. 1) has six Top DuoRun groups, and machines are now being designed for at the end of the dryer section a double- speeds up to 1800 m/min. Main require- tier group with six cylinders. This was ments on the drying section of these fast- the first paper machine in the world to running paper machines are high avail- Introduction have only one double-tier drying group. ability and high specific evaporation During the course of dryer section devel- The start up was in 1993 and now capacity, with min- opment, the bottom cylinder of a slalom operates at more than 1500 m/min. imum energy out- drying group was replaced by grooved lay for the product guide rolls for the dryer fabric. This was grade in question. the beginning of single-tier paper drying. The Top DuoRun In front of the run-in gusset between the Top DuoRun with its overhead grooved roll and dryer fabric, a stabilizer The latest generation of printing paper dryer aggregates had to be installed to prevent web lift due machinery is designed for operating and DuoStabilizers to air inclusions. This led to problems in speeds up to 1800 m/min. These high meets all these the edge zones of the web, where air speeds and much higher investment requirements. The inflow prevented fixing to the dryer costs place more stringent requirements web is supported fabric. on the drying section: throughout the entire drying pro- The author: cess, and in case For high operating speeds, the grooved I High runnability M. Oechsle, of a break waste rolls were replaced with suction guide- I High specific evaporation Drying Technology material falls on a rolls. These fix the web over its entire I Low energy consumption conveyor belt which width to the dryer fabric and counteract I High paper quality feeds it to the pulper. Thanks to short centrifugal force. The pre-suction zone of I Lowest possible investment costs dryer groups at the beginning and end the roll, where the entrained air is sucked of the drying section, longitudinal web away, replaces the web stabilizer. stretch and lateral shrinkage are compen- In order to meet all these requirements at sated so that folds and breaks are elimi- such high operating speeds, Voith Sulzer nated. The combination of DuoStabilizers developed the Top DuoRun dryer section and drilled guide-rolls fixes the web on Combi DuoRun concept described in the following. the dryer fabric, which not only stabilizes The Voith Sulzer Combi DuoRun is a operation in the dryer section but also combination of single-tier dryer group in makes for lower operating costs. The the first part, and double-tier dryer group ropeless tail transfer system ensures in the second part of the dryer section. In The Top DuoRun (see Fig. 2) comprises a safe and reliable transfer through the modern paper machines this concept single-tier dryer group with overhead dryer section, and an intermediate floor operates successfully at speeds up to drying cylinders. Under the cylinders are underneath allows better space utiliza- 1500 m/min. With rising speeds, the num- drilled guide-rolls, together with Duo- tion. The DuoCleaner keeps the dryer ber of double-tier drying groups and the Stabilizers. Compact short dryer groups fabric clean at all times, thus ensuring number of cylinders per group has been are installed at the beginning and end of good evaporation and reducing dirt con- reduced since problems were caused by the drying section. 26

Fig. 1: Combi DuoRun.

Fig. 2: Top DuoRun.

1

2

Due to the overhead tensioning of the enclosure smaller and less expensive, but ders are equipped with fold-out doctors dryer fabrics, the space under the single- better use is made of available space. to allow easy cleaning of the surfaces. tier dryer group is free. As shown in The fabrics in the first dryer groups Fig. 1, this was already utilized in are cleaned continuously by DuoCleaners Schwedt by installing an intermediate during operation. floor for the waste conveyor belt. The Main components of the Top DuoRun additional basement space can be used Rising demands on paper quality make as roll and clothing store or for secon- machine cleanliness very important these All drying cylinders are dewatered by a dary aggregates. Not only is the cellar days. For this reason all the drying cylin- stationary suction siphon. The suction Paper Machines 27

Fig. 3: Duostabilizer. siphon is ideal for fast-running machines diameter as in the suction-roll, so that it since it works independently of operating can be designed for low pressure losses. speed. For these reasons smaller, lower-cost fans can be used.

The ropeless tail transfer system is reliable and trouble-free. Tail removal Comparison of electrical energy con- from the cylinder surface and attachment sumption shows that the DuoStabilizer/ to the dryer fabric is assisted by air blow drilled roll combination uses about 70% nozzles. Transfer in the drying section via less energy than a suction roll, and about the DuoStabilizer transfer zone and drilled 60% less than the web stabilizer/grooved roll is likewise assisted by air blowers. guide roll combination. Vacuum measure- This system is simple and maintenance- ments on DuoStabilizers in production friendly, and due to the short intermittent machines gave the following results: blower cycles air consumption is low. At the end of the dryer section the web is supported on the last drying cylinder, and In gap between outgoing cut by a water jet. wire and box 70-250 Pa

In dryer wire suction Together with the drilled guide roll, the guide roll 250-700 Pa 3 DuoStabilizer sucks the web on to the dryer fabric and keeps it free of creases to In gap between incoming (about 0.7 litres/min). This means that it allow reliable transport from roll to roll. wire and box 10-30 Pa can be used continuously throughout The vacuum in the gap between outgoing production. Even at low basis weights, fabric and box and in the fabric guide roll there is no visible interference in the is provided by the DuoStabilizer, which is web. At the present time the DuoCleaner connected to a vacuum system. The gap The use of DuoStabilizers allows the eva- is used very successfully for basis is sealed at the top of the DuoStabilizer poration distance between cylinders to be weights between 35 and 160 g/m2.It by a felt seal across the web and by air- extended by up to 30%, without changing keeps the dryer fabric clean and thus jets at the sides. The felt seal folds away the roll diameter. helps to improve water evaporation on the to allow changing of the dryer fabrics. On side of the web away from the cylinder. the operator side a transfer zone 500 mm This increases drying capacity and reduc- long is incorporated in the DuoStabilizer The DuoCleaner (Fig. 4) is a fabric clean- es web curling. Installed on a testliner and drilled roll. During the transfer pro- ing device operated by water under high machine, it was found that the DuoClean- cedure vacuum is applied to the transfer pressure. Dirt is removed mechanically, er rapidly increased the air permeability zone only. The amount of air to be and the vacuum zone around the water of the dryer fabric from 270 to 375 cfm sucked out in the DuoStabilizer is rela- nozzle sucks away the water and dirt par- (new condition: 400 cfm). tively small compared with the suction ticles rebounding from the fabric. guide-roll, since the felt seal keeps out Since shutdowns are not required for the air entrained with the fabric. Fur- fabric cleaning, machine runability is thermore, the DuoStabilizer vacuum con- The DuoCleaner operates at a pressure of improved and these components soon nection is not limited by the bearing 200 to 300 bar and uses very little water pay for themselves. 28

Fig. 4: DuoCleaner fabric cleaning device.

Features of the Top DuoRun High specific evaporation High availability Thanks to the high specific evaporation, The Top DuoRun ensures high availabili- Stable running dryer sections are shorter and invest- ty, with short down times and consistent- After leaving the last press nip, the web ment costs lower. To increase the heat ly high paper quality. Its stable run- is sucked on to the fabric of the first dryer transfer from steam to web, all cylinders ning characteristics reduce web break group and fixed. It is then supported on are fitted with spoiler bars. In order to frequency to a minimum. A significant the fabrics right through the dryer sec- reach such a high evaporation capacity, advantage of this cylinder arrangement is tion, thus ensuring stable running and the heated web must be able to dry out the short tear-off time required. Waste reducing the risk of a break rupture to a sufficiently after leaving the cylinder. To material falls on to the conveyor belt minimum. The combination of DuoStabi- this purpose the DuoStabilizer provides a below and is transportet automatically to lizers and dryer fabric drilled guide roll long evaporation distance. Since most of the pulper. As a result, time-consuming transports the web reliably from cylinder the evaporation takes place below the removal of waste from the drying section to cylinder. cylinder in the Top DuoRun, hot air blow is no longer necessary. The ropeless pipes are installed at this point. These edge strip transfer system ensures fast blow pipes are dimensioned so that more and reliable transfer, without any time At the cylinder runout point the DuoStabi- fresh air is blown into the centre of the wastage due to rope wear or breakage. lizer fixes the web by suction on the dry- machine. The moist air then flows equally er fabric. The vacuum balances out the toward the operator and drive sides of centrifugal force around the drilled guide the machine, thus removing the water Controlled paper shrinkage roll and thus keeps the web fixed to the vapour on both sides to ensure a uniform Due to the rising web temperatures at the dryer fabric. humidity profile. beginning of the dryer section, the initial falls off and web extension increases. When the web is tensioned, it extends in the longitudinal direction and its width shrinks.

The DuoStabilizer fixes the web to the dryer fabric by suction at the cylinder take-off point. Relatively small forces are required to remove the web from the cyl- inder surface, so that longitudinal exten- sion and lateral shrinkage are low. Thanks to the small dryer groups, exten- sion in the wet part of the web can be compensated by speed adjustment, thus preventing folds.

In single-tier dryer sections, the web is firmly fixed to the dryer fabric and pre- vented from shrinking. This generates 4 web stresses which can cause tearing. By Paper Machines 29

Fig. 5: V-Top DuoRun.

5

means of short dryer groups at the end of V-Top DuoRun the dryer section, allowance can be made The V-Top DuoRun (see Fig. 5) was by speed adjustments for web shrinkage, developed in order to minimize paper thus preventing breaks. machine investment costs. It likewise comprises a single-tier dryer section, but arranged in vee-form. At the begin- Prevention of curling ning and end of the dryer section short One-sided drying makes the web tend to horizontal dryer groups can be installed. curl. This curling tendency is caused in The vee-configuration is more compact the dryer section by unequal water dis- than the horizontal arrangement, and tribution between the top and reverse allows more effective utilization of space sides of the web, which therefore curls below the drying section. toward the most recently dried side. Tests on paper machines in practice have shown that curling can be controlled The V-Top DuoRun is accessible from quite precisely by adjusting side-to-side several servicing levels. In case of web humidity distribution. This can either be break, the waste material falls on to a done in the drying section or afterwards. conveyor belt below the machine. With According to these tests, one-sided dry- the Vee configuration, drying capacity ing has no effects on other paper charac- can be increased without sacrificing teristics. space, thus making it ideal for rebuilds. For the same number of drying cylinders, The first Top DuoRun will start up in the vee configuration is about 20% Sweden early in 1996 on a newsprint shorter than the horizontal configuration. machine designed for an operating speed of 1800 m/min. 30

Paper Machines Division: Coating with the JetFlow F

JetFlow F is the name of our new blade- considerable brain-storming between the outset, they met all quality demands coater generation. The new Voith Sulzer customers and engineers to make it for fine papers – although the coating blade-coater was developed to maturity feasible. In order to put the idea down on formulations used here had been devel- in only three paper – literally – we converted our pilot oped and optimized over some decades years, and is now machine in Heidenheim accordingly. for roll-type coaters. well-proven in practice. With This was where the customer contribu- enormous poten- 2. Development tion to development work really started. tial for output and After innumerable tests, rebuilds and If the JetFlow F could meet roll-type coat- product quality, optimizations, the JetFlow F was finally ing quality with these formulations, what the JetFlow F sets born. Parameters such as jet angle, quality levels might it reach with formula- new standards in length, velocity and consistency for the tions optimized for jet-? – Better ones! the paper industry. right coating quantity and pressure were If we were to worked out. A significant feature is the adopt Olympics curved outflow lip (patented) resulting 4. Results terminology, we from this development work. At the same Many paper producers are interested in The author: Bernhard Kohl, could say that the time a coating deaerator was developed the JetFlow F because they have prob- Application JetFlow goes fast- for this system which likewise improves lems with their existing coaters. Exhaus- engineering coaters er, higher, further all other free jet coaters. tive tests on the Heidenheim pilot coating and cleaner – in machine have proved the versatility of the other words: JetFlow F, and market acceptance is shown I This coating machine runs faster 3. Trials by the following reference list (Tab. 1). (better runnability) In May 1993 the first two JetFlow F coat- I Coating quality is higher than with ers were installed in the USA. Right from other types I It has wider applications than other Tab. 1: JetFlow F Reference list types width speed I It uses jet-sizing – the cleanest way to Customer Coating system mm m/min Paper grades coat paper. Rapids 64 2 JetFlow F Off- 3680 1070 80-200 g/m2 USA CM single and double coating This article summarizes the development Biron PM 24 1 JetFlow F On- 3680 762 LWC and technology of the JetFlow F. As shown USA CM 60-80 g/m2 by experience, the success of this new Plattling SM 11 2 JetFlow F Off- 7610 1550 LWC blade-coater is due to a complete under- Germany CM 35-70 g/m2 standing of the principles and interrela- 2 tionships involved. Gratkorn SM 9 2 JetFlow F Off- 6450 1250 80-240 g/m Austria CM single and double coating Kuusankoski PM 7 2 JetFlow F On- 4660 900 60-150 g/m2 1. Basic principle Finland CM Precoating with Speedsizer In the early 1990s, a well-known USA N.N. 2 JetFlow F On- 7680 1400 LWC + MWC paper producer had a good idea – to Finland CM 6-16 g/m2 develop a free jet coater for a predeter- N.N. (LOI) 2 JetFlow F On- 7560 1500 LWC mined coating thickness, evened out by a Brazil CM 40-70 g/m2 blade. This idea was not new, but it took Paper Machines 31

Fig. 1: Schematic arrangement of the JetFlow F.

Fig. 2: 1 JetFlow F coating principle.

5. Operating principle A thin coating film is applied in the form of a jet at a defined angle (Fig. 1). Air Wash water entrainment is prevented by the vertical force component. Since the paper web moves faster than the jet, the application FS area is greatly extended. This makes the bypass film much thinner and more uniform than in conventional coaters, with the follow- Deaerator Pressure filter ing benefits: DS I Better cross-profile I Lower blade loading I Smaller recirculation flow

Coating colour

In order to eliminate the air entrainment Foam pipe problem applying to all other types of coater, the coating jet is preceded by a deaeration unit (Fig. 3). In addition, the curved outlet lip ensures centrifugal mix- Service ing of the coating material, so that by the tank time it reaches the web it is completely free of air. Coating colour recovery

Pump 6. Technology 2 The JetFlow F induces no pressure pene- tration as in conventional coaters, but dewatering during the dwell time is unre- Tab. 2: JetFlow F Applications successfully tested stricted and therefore more uniform. Fur- Raw paper: thermore, the coating material is more – wood-free 50 - 140 g/m2 liquid when it reaches the blade. After 2 equalizing, the coating structure is thus – wood-containing 28 - 290 g/m better. Coat weight 4.5 - 17 g/m2 Speed range 330 - 1800 m/min Solids content (4)50 - 70 % 7. Clean operation The JetFlow F is a closed system, and Viscosity range (140)1200 - 2400 mPa · s coat reaches the paper without film (100 rpm Brookfield) splitting. As a result, coating takes place cleanly without any spray, mist or depos- its. Between the nozzle, blade and return through the machine at 1500 mpm. The yet to assess overall potential, but based flow plate of an LWC coater, for example, range of applications tested so far on on test results so far we are confident of a mirror-finish film without any stripes the pilot machine is very wide (Tab. 2). meeting all market challenges. can be seen over a distance of 7 m Practical experience is not sufficient as 32

Finishing Division: The Janus Concept – the future of paper finishing

For a number of uncoated and coated tic covers, the distinctly lower - advantages of the machine calender lie in paper grades, softcalenders installed ing temperature compared with the soft- its efficient operation, whereby the unit- online and offline are also currently calender and the considerably lower ing of these two positive arguments were being used with success for calendering energy requirement achieved as a the basis for the development of the soft- in addition to the proven supercalen- result. calender, which in meantime has estab- ders. The essen- lished itself on the market. tial challenges for the future will Laboratory results will be discussed Before dealing with the developments of be improvement with respect to a comparison between the Janus Concept, a completely new of the efficiency the Janus Concept and supercalender calendering technology, it is meaningful of the manufactur- for highly compressed paper applica- to take stock between the supercalender ing process with tions, i.e. LWC-Roto and SC-A, which and the softcalender in order to clearly simultaneously show that the gloss and smoothness show the arguments decisive for the new increasing quality values and printability for such papers process. requirements. The are comparable with the current SC- experience avail- finish, also for PM and SM speed. Table 1 initially shows the calender types able for both pro- which could currently be considered for a cesses results in wide variety of papers, whereby the main the necessity of difference here lies in the higher number developing com- Introduction of nips of 8-13 in the case of the super- pletely new calen- Until the beginning of the 1980’s, calen- calender, compared with 1-4 individually dering concepts to dering was carried out exclusively by controllable nips of the softcalender. If meet these mar- means of supercalenders and machine these criteria are transferred to the calen- ket requirements. calenders. While the supercalender is dering process, the supercalender is distinguished by its technological advan- accordingly provided with considerably tages due to the use of elastic rolls, the more nips for densification the paper via The following pro- vides a summary of the arguments Table 1: Comparison between supercalender and softcalender decisive for the Supercalender Softcalender development of No. of nips 8 -13 1- 4 The authors: new calendering U. Rothfuss, concepts. The Cover material native fibre/plastic plastic Janus Technology technical and tech- Centre, Cover hardness 85 - 91° ShD 85 - 94° ShD and U. Gabbusch, nological possibil- Max. line load 350 N/mm 350 N/mm Development ities of the new Max. specific pressure 39 - 50 N/mm2 31- 40 N/mm2 Janus Concept to be installed online and offline are pre- Max. surface temperature 100°C 200°C sented. In comparison to the classic Roll diameters smaller bigger supercalender, the exceptional advan- Load changes 2/revolution 1/revolution tages lie in online integration for each Speed 450 - 900 m/min PM/SM speed production speed, the lower number of rolls in conjunction with the use of plas- Finishing 33

pressure and temperature, while in the softcalender, a distinctly higher amount Table 2: supercalender advantages/disadvantages of energy has to be supplied for web den- Advantages Disadvantages sification per nip for a comparable calen- dering result. Many nips with high degree Limited speed range of coverage Furthermore, it is important to show, on Online installation not possible the basis of Table 1, to what extent the Good distribution of Limited temperature range two calendering processes additionally calendering work between differ from each other (1). load and temperature Small influence onto two-sidedness Process technically and techno- The table clearly shows why higher calen- Low efficiency because logically wellknown for decades dering temperatures are necessary for of roll and reel change downtime the softcalendering process. The larger All paper grades can be finished Dependence of line load from roll dimensions are effecting a wider con- at high quality top to bottom nip tact zone, which results in a lower com- Low amount of energy pressive stress being produced based on High space requirement to be installed a comparable line load compared with the with additional supercalender.

For a conversion energy comparable with the supercalendering process, consider- Table 3: Softcalender advantages/disadvantages ably higher surface temperatures are accordingly necessary in the case of the Advantages Disadvantages softcalender. Online installation possible Not suitable for all paper grades An important point is the energy to be Individual controllable single nips High amount of energy to be installed installed for both calendering processes. Based on a 8 metre wide plant, energy Minimisation of two-sidedness Compression lines problem can occur has to be installed for a four-nip online Wide load and temperature range Only few nips calender with about 50% more in com- parison to two offline 12-roll supercal- High efficiency because of less enders. roll changes

For online installations A further difference lies in the fact that low space requirement without covers made of or a composition add. personnel of cotton and wool are still used to a large extent in the supercalender, in con- trast to the softcalender, where only plas- tic covered rolls are provided. The advan- ensure a long life time. Cotton rolls by er, compared with the plastic covers in tages of the plastic covers are given by contrast are subject to a higher mechani- the softcalender. The previously lower their higher mark resistance and a better cal load because of the double load loading capacity of the plastic covered wear resistance, which finally serve to change per revolution in the supercalend- rolls is an argument which is currently 34

still responsible for the main use of sidedness, due to individually controlla- finish being produced which is compar- cotton covers in supercalenders. How- ble single nips and the wide temperature able to or better than a supercalender. ever, one cannot fail to notice that plastic and line load range. covers are increasingly being used in The task basically represents the total supercalenders, whereby their installation It should be mentioned that the success- synergy between the supercalender and positions are mainly in the upper calend- ful use of the softcalender in the case of the softcalender. Because of this double er area. In this connection, a technologi- specific paper grades, e.g. high gloss task, the concept was given the name of cal aspect resulting from moving to plas- qualities, was initially made possible by the ancient god with two faces: the Janus tic covers should not remain unnoticed. engineering advances and the additionally Concept. One face reflects tradition, the As a consequence of the internal friction, created preconditions from the paper- supercalender and the softcalender, the on account of their larger hysteresis, the makers. The latter mentioned includes, in other looks ahead towards new calender cotton covers are subject to a higher addition to levelling the cd-profiles, a technology. temperature development, which is coating formulation which has been con- simultaneously a component of the sistently adjusted to the changed condi- conversion energy. In the case of plastic tions of the softcalender. Table 4 Janus Concept requirements. covers by contrast, a clearly lower tem- I perature development is noticed. A Finish of all paper grades at supercalender equipped with such rolls The necessity to reconsider current high quality I produces lower gloss and smoothness calendering possibilities is also under- online and offline installation values under comparable calendering lined by the results of extensive tests possible I conditions as a result. carried out for a highly compressed SC-A High efficiency including less paper (3). The core statement here was roll changes I that the printability of a SC-A paper, Low space requirement without For the purpose of further clarification, supercalendered with eleven nips, can add. personnel I the advantages and disadvantages of also be achieved with only four nips of a Low amount of energy to be both calendering processes are shown in softcalender when the temperatures of installed I the Tables 2 and 3 (2). the chilled iron rolls reach minimum Less energy loss during operation I 160°C and the compressive stresses of Minimisation of two-sidedness I The list essentially shows that the super- all nips are in a range, as are present in Wide load and temperature range calender cannot follow the current the bottom nip of a supercalender loaded speeds of modern paper and coating with 350 N/mm. However, this applies machines. The capacity of the standard only to a speed range of about 500- The core principle of the Janus Concept two supercalenders is frequently exceed- 700 m/min, i.e. the calendering speed of is that only the number of nips necessary ed today. A second or third supercalend- the supercalender usual for this type of for calendering a specific paper quality is er involves higher investment costs for paper. used. Missing nips, which are to be buildings and also add. personnel costs. equated with mechanical conversion The main features of the softcalender are energy, are not replaced by thermal ener- summarised in Table 3. gy only. Based on the results of numer- The Janus Concept ous analyses which showed that the high Summarised, the main advantages of the Decisive for the development of a new number of nips as used in the supercal- softcalender are its high efficiency and calender concept was the requirement for ender is unnecessary for the actual calen- flexibility, whereby the latter mentioned an online installation for any conceivable dering process, a maximum of eight rolls feature refers to minimisation of the two- production speed in conjunction with a resulted for the Janus Concept. Finishing 35

Fig. 1: Janus Concept with 2 x 5 rolls.

Fig. 2: Janus Concept with 1 x 8 rolls.

Fig. 3: Janus Concept: Formula.

An initial precondition for online integra- tion of the Janus Concept is controllabil- ity of paper web threading at full PM or SM speed. Several years of intensive tests on a pilot plant, developed specifi- cally for this purpose, showed that web threading can take place successfully by a combination of aerodynamic elements with ropes and belts.

The most significant difficulties did not occur at the beginning as actually expect- ed with web guidance within the calend- 12 er, but rather with web transfer to the calender. The control of problem-free From the wide range of information This spatial representation is based on web threading also assumes the drive of acquired from available supercalenders, a the equation shown below which makes it all rolls installed in the calender. mathematical description of the distribu- possible to predetermine the necessary tion of the calendering work in the nips calendering temperature and compressive of a calender could be found with the aid stress as a function of speed or dwell Against the background of the finish, of extensive analyses. time for any number of nips. In principle, comparable with the supercalender in this equation describes nothing else than conjunction with minimum two-sided- Figure 3 shows the calendering range of the influence of these parameters on, e.g. ness, one solution could be the division the Janus Concept in three-dimensional the bulk of a paper. Equations can natu- of the supercalendering process into two form. Illustrated in this case for the 8-roll rally also be used in a similar form for processes, represented by the two version, for example, is the bulk of a specific gloss or smoothness values for stacks, consisting of 5 rolls respectively. SC-A paper, applied to the Y-axis, as a the respective customer product, i.e. for Additionally it was examined how a single function of the dwell time, applied to the the respective paper quality. stage solution with 6-8 rolls could meet X-axis and compressive stress, applied to all requirements. Like the supercalender, the Z-axis. As curved surfaces in space a roll reversing nip must also be provided the bulk at 100 and 150°C surface tem- These calculations result, particularly in for two-sided calendering. The two- perature can be seen. the case of papers to be highly com- sidedness can be controlled by influenc- pressed, in necessary nip numbers

ing the increase of line load nip by nip, T) which a softcalender can normally not -5 using different roll materials and precal- provide. culated nip widths. 0.88 -0,421t 0.86 ]t·e

0.84 -0,093p The question naturally arises as to how 2 In order to make this “multi-nip online 0.82 100˚C 45 /g the energy plus of the Janus Concept is 3 calendering process” possible, a whole 0.80 150˚C 50 achieved compared with the supercalend- 0.78 1,378-0,00356 ·T-(0.00825-5,12 ·10 series of technical elements are neces-

Bulk cm 55 ≈

er, since the same result is to be 0.76 /g] sary. The most important features of the 3 0.1 0.37 60 achieved with less nips at a considerably 0.63 0.9 Janus Concept are accordingly listed in dwell time ms compressive stress N/mm bulk [cm higher calendering speed. 3 p-[0,039+(0,188-0,00112 ·T)p·e Table 5. 36

Due to the considerably smaller rolls and high line loads compared with the soft- Table 6: Energy balance Janus Concept – softcalender – supercalender calender, compressive stresses up to 4-Nip Softcalender 2 Supercalender Janus Concept 60 N/mm2 can be realised in the Janus installed consumed installed consumed installed consumed Concept, whereby the development of suitable plastic covered rolls took place Heating at the same time. The new roll generation capacity 4320 KW 3140 KW 1950 KW 1300 KW 1860 KW 1430 KW withstands the high mechanical and ther- Drive power 3300 KW 2100 KW 2600 KW 1600 KW 2480 KW 1580 KW mal loads whilst maintaining the familiar Power for units 520 KW 400 KW 950 KW 440 KW 260 KW 140 KW advantages of low sensitivity to marks and high wear resistance, which ensures Power for winder 0 KW 0 KW 720 KW 360 KW 0 KW 0 KW a long life time. Total kW 8140 KW 5640 KW 6220 KW 3700 KW 4600 KW 3150 KW

Table 5: Janus Concept – Features its own control loop. Thus, a total of four was taken as a basis. For the supercal- I High-speed open-nip threading control elements are available for thermal ender an operating speed of 800 m/min system reduction of two-sidedness. respectively at a design speed of 1000 I All rolls driven m/min was taken as a basis. I New generation of plastic covered rolls The Janus Concept accordingly moves in I Midrange-heated intermediate a temperature level above the supercal- Assumed as maximum surface tempera- rolls with new type of surface ender, however, distinctly below the tem- tures were 85°C for the supercalender, treatment peratures necessary for the softcalender. 150°C for the Janus Concept and 200°C I Heated top and bottom roll In conjunction with the considerably for the softcalender. The maximum line I Individual temperature control smaller roll diameters compared with the loads are about 400 N/mm for the super- of all thermo-rolls softcalender and utilization of thermal calender, about 550 N/mm for the Janus I Lever-type calender with energy of a heating roll in two nips, the Concept and about 370 N/mm for the overhanging load compensation heating capacity to be installed is drasti- softcalender. cally reduced and the heat losses to the atmosphere are considerably reduced as The table clearly shows that the Janus In addition to increasing the mechanical well. Table 6 shows the capacities to be Concept has an approximately 15% lower conversion energy, the proportion of installed, as well as the energy consump- energy requirement compared to two thermal energy also had to be adapted to tion of the Janus Concept in comparison supercalenders, and an approximately the new concept. By using new types of to an online 4-nip softcalender or two 44% lower energy requirement compared heat rolls, surface temperatures of about 12-roll offline supercalenders for an to the softcalender. The Janus Concept 150°C with minimum cd-profile devia- assumed machine width of 8 m. also has significant advantages for the tions are achieved. Each roll is allocated energies to be installed: 26% less than a separate temperature control loop. The the supercalender and 45% less than the oil-heated deflection compensation rolls For the two calenders to be installed softcalender. in the top and bottom position permit online, the Janus Concept and soft- surface temperatures of about 130°C, calender, an operating speed of 1200 Further essential features of the Janus whereby each roll is similarly allocated m/min at a design speed of 1400 m/min Concept are in the consistent realisation Finishing 37

Fig. 4: Line load characteristic of the Janus Concept in comparison to a conventional or compensated calender.

Fig. 5: SC-A grade 56 g/m2, gloss vs. line load.

Fig. 6: SC-A grade 56 g/m2, printgloss vs. line load.

of the constructive functional units of the relatively limited range of the super- 54 the new lever-type calender generation calender. 51 48 with overhanging load compensation, 45 which considerably improves the quality The available high compressive stress, 42 39 of line load distribution in the individual the steep line load characteristic, as well 36 Gloss Gardner % nips. as the temperature range up to 150°C 33 30 when using seven nips, create the pre- 250 350 450 550 250 350 condition for calendering virtually all Line Load N/mm JANUS CONCEPT: 120° C, 650 m/min In conjunction with the achieved weight paper grades at the respective PM and JANUS CONCEPT: 120° C, 1000 m/min Supercalender: 70° C, 650 m/min reduction of 50% for the elastic rolls, the SM speed, based on the Janus Concept. 5 weight compensation distinctly increases the operating capacity of the Janus Con- 79 cept. With comparable line load in the The test results achieved according to the 76 73 bottom nip, the overhanging load com- Janus Concept with SC-A paper and LWC 70 pensation and reduction of the roll paper for rotogravure printing are dis- 67 64 weights as such enables a distinctly high- cussed in the following. A laboratory 61 58 er line load in the above located nips, i.e. calender with all features of the Janus Printgloss Gardner % 55 the line load characteristic from bottom Concept will be commissioned in the 250 350 450 550 250 350 Line Load N/mm to top becomes steeper. Figure 4 shows summer of this year and will be available JANUS CONCEPT: 120° C, 650 m/min the line load range of each individual nip for customer tests from autumn onwards. JANUS CONCEPT: 120° C, 1000 m/min Supercalender: 70° C, 650 m/min of the Janus Concept in comparison to a 6

One can see that the gloss of the paper 1

3 Calendering of SC-A paper acc. supercalendered at 650 m/min is exceed-

5 to the Janus Concept ed by the Janus Concept even at a PM

7 The tests were carried out with a Europe- speed of 1000 m/min at 120°C surface

Number of Nips 9 an standard SC-A paper. The basis weight temperature and line loads of about 2 11 was about 56 g/m , the ash content was 350 N/mm. The calendering temperature 050 100 150 200 250 300 350 400 about 31%. These papers are currently which is 50°C higher compared to the Line Load N/mm being calendered with the addition of supercalendering process, has a strongly conventional Supercalender compensated Supercalender steam on two 12-roll supercalenders at positive effect on the gloss result in this JANUS CONCEPT 4 250-280 N/mm line load and about case. Figure 6 appropriately shows the 70°C surface temperature at 650 m/min. print gloss of samples printed by the conventional calender or a compensated rotogravure process. calender. The following results show a comparison of the standard supercalendering process For the print gloss, virtually the same The steeper the line load characteristic, to the Janus Concept, whereby in the correlations can be seen as previously the less the line load differences are case of the Janus Concept, both the cur- discussed for the paper gloss. At between the bottom and top nip, which rent calendering speed of 650 m/min as 350 N/mm line load, the print gloss of has a positive effect on the reduction of well as the PM speed of 1000 m/min are paper supercalendered at 650 m/min can the two-sidedness (4). Clearly distin- taken into account. Figure 5 initially be exceeded, even at a PM speed of guishable is also the enormous line load shows the paper gloss according to 1000 m/min. Figure 7 shows the rough- range of the Janus Concept compared to Gardner as a function of line load. ness PPS-10 S over the line load. 38

Fig. 7: SC-A grade 56 g/m2, roughness vs. line load.

Fig. 8: SC-A grade 56 g/m2, bulk vs. line load.

Fig. 9: SC-A grade 56 g/m2, blackening vs. line load.

printability comparable to that of SC 1.5 0.86 m

µ paper with less blackening. 1.4 0.84 /g 1.3 3 0.82 Summarised, this test shows that the 1.2 0.80 Bulk cm Janus Concept is capable of producing 1.1 0.78

Roughness PPS-10 S with only seven nips at maximum 1.0 0.76 250 350 450 550 250 350 250 350 450 550 250 350 450 N/mm line load, even at PM speed, Line Load N/mm Line Load N/mm a paper with a printability comparable JANUS CONCEPT: 120° C, 650 m/min JANUS CONCEPT: 120° C, 650 m/min JANUS CONCEPT: 120° C, 1000 m/min JANUS CONCEPT: 120° C, 1000 m/min to that of the supercalender with less Supercalender 70° C, 650 m/min Supercalender: 70° C, 650 m/min 7 8 blackening and a simultaneously higher print gloss. The diagram clearly shows that the 60 roughness of the supercalendered com- 58 56 parison paper by means of the Janus 54 52 Concept could be achieved at a compar- 50 Calendering of LWC-rotogravure paper 48 able calendering speed of 650 m/min at 46 according to the Janus Concept 44 line loads of about 450 N/mm. However, 42 The tests were carried out with a Europe- Blackening Index % 40 due to the surface temperature of only 250 350 450 550 250 350 an standard LWC rotogravure paper. The 120°C in this case, this was not com- Line Load N/mm basis weight was about 58 g/m2 the coat- JANUS CONCEPT: 120° C, 650 m/min pletely possible at a PM speed of 1000 JANUS CONCEPT: 120° C, 1000 m/min ing weight was about 9 g/m2 per side. Supercalender: 70° C, 650 m/min m/min. Figure 8 shows the densification 9 The papers are currently being calen- or bulk as a function of line load. dered on two 12-roll supercalenders at A further important criterion, particularly 270-300 N/mm line load and about 65°C in the case of SC-A papers, is the so- surface temperature at 700 m/min. One can see that the compression of the called blackening. Blackening occurs with supercalendered paper by the Janus Con- high densification of the papers due to cept at 450 N/mm line load is also collapsing of the fibres. These fibres then The following results show a comparison achieved at a PM speed of 1000 m/min. appear transparent in transmitted light of the standard supercalendering process Based on knowledge from earlier tests and black in reflected light.With the aid of to the Janus Concept, whereby in the that the printability of such paper was an image analysis system developed at case of the Janus Concept, both the less correlated with smoothness or the Technical University in Darmstadt, it current calendering speed of 700 m/min roughness rather than with densification, was possible to measure the blackening as well as the coater speed of 1400 a comparable printability was also to be in the form of a blackening-index, where- m/min are taken into account. Figure 10 expected in this case (5). by the larger percentage figure indicates initially shows the paper gloss Gardner more blackening. The respective results as a function of line load. One can see The respective rotogravure tests carried are summarised in Figure 9. that the gloss of the paper supercalen- out confirmed this in all respects. Both dered at 700 m/min is exceeded by the from a visual assessment aspect and also Janus Concept also at an SM speed of from the number of counted missing-dots One can clearly see that the blackening 1400 m/min, 135°C surface temperature in the quarter-tone range, no differences index is lower in the case of papers and 350 N/mm line load. of the supercalendered paper to the calendered according to the Janus Con- Janus Concept calendered samples were cept. This means that the Janus Concept Figure 11 appropriately shows the to be seen. enables paper to be calendered with a smoothness Bekk. The diagram clearly Finishing 39

Fig. 10: LWC-roto 58 g/m2, gloss vs. line load.

Fig. 11: LWC-roto 58 g/m 2, smoothness vs. line load.

Fig. 12: LWC-roto 58 g/m 2, roughness vs. line load.

Fig. 13: LWC-roto 58 g/m2, bulk vs. line load.

shows that the Bekk smoothness of the 4000 0.86 0.84 supercalendered paper by the Janus 3500 0.82 /g

Concept at double the speed of 3000 3 0.80 1400 m/min at 135°C surface tempera- 2500 0.78 0.76

2000 Bulk cm ture and 350 N/mm line load is virtually 0.74 1500 reached and already exceeded at Smoothness Bekk s 0.72 1000 0.70 450 N/mm line load. 250 350 450 550 250 350 250 350 450 550 250 350 Line Load N/mm Line Load N/mm JANUS CONCEPT: 135° C, 700 m/min JANUS CONCEPT: 135° C, 700 m/min Figure 12 shows for the sake of com- JANUS CONCEPT: 135° C, 1400 m/min JANUS CONCEPT: 135° C, 1400 m/min Supercalender: 65° C, 700 m/min Supercalender: 65° C, 700 m/min pleteness also the roughness. Measured 11 13 according to PPS-10 S, the roughness of the paper supercalendered at 700 m/min With this new calendering technology, 0.85 m by the Janus Concept at 1400 m/min and µ papermakers are provided with an instru- 0.80 135°C surface temperature is already ment which fully meets the initially men- 0.75 exceeded at line loads of 350 N/mm. tioned requirements for calendering high 0.70 quality papers in “supercalender quality” 0.65 also at PM or SM speed with high Roughness PPS-10 S 0.60 Figure 13 finally shows the densification 250 350 450 550 250 350 efficiency and distinctly reduced energy or bulk as a function of line load. The dia- Line Load N/mm consumption. JANUS CONCEPT: 135° C, 700 m/min gram clearly shows that the bulk of the JANUS CONCEPT: 135° C, 1400 m/min Supercalender: 65° C, 700 m/min paper supercalendered at 700 m/min cor- 12 responds to the sample calendered according to the Janus Concept at 1400 already to be expectedfrom the calender- m/min, 135°C surface temperature and ing results, no differences in the print- ability of the samples supercalendered at

70 700 m/min to the samples calendered 67 64 according to the Janus Concept at 61 58 1400 m/min, whereby the latter were 55 52 characterised by a higher print gloss 49 due to the higher calendering tempera- Gloss Gardner % 46 43 40 ture. 250 350 450 550 250 350 Line Load N/mm JANUS CONCEPT: 135° C, 700 m/min Summarised, this test also shows that References JANUS CONCEPT: 135° C, 1400 m/min the Janus Concept is capable of produc- (1) Rothfuss, U. – A review of surface characteristics and ° Supercalender: 65 C, 700 m/min printing results from soft and supercalendered papers. TAPPI 10 ing with only seven nips but double the Finishing Conference, Chicago 1994 speed at 350-450 N/mm and 135°C sur- (2) Marleaux, H.P., Cramer,D., Kathan, C. – Von Matt bis 350 N/mm line load, i.e. calendering con- face temperature, a paper which is abso- Hochglanz – Praxiserfahrungen mit On-/Offline-Softkalandern für gestrichene Papiere. Wochenblatt für Papierfabrikation ditions under which more favourable lutely comparable with the supercalen- 122 (1994), Nr. 8, 296 – 301 gloss and roughness values could be dering process. Both these tests based (3) Rothfuss, U. – Inline- und Offline-Satinage von holzhalti- gen, tiefdruckfähigen Naturpapieren. Wochenblatt für Papier- achieved by the Janus Concept. on the example of the highly densified fabrikation 121 (1993), Nr. 11/12, 457 – 466 paper grades, SC-A and LWC rotogra- (4) Bresser, H., Kayser, F. – SNC – Der Superkalander der 90er Jahre. Das Papier 43 (1989), Heft 10A, 169 – 182 The rotogravure printing tests carried out vure, impressively show the enormous (5) Dr. Lesiak, M., Rothfuss, U. – Online-Satinage von altpa- for this comparison showed, as was potential of the Janus Concept. pierhaltigen SC-Papieren. 25. EUCEPA Conference, Wien 1993 40

Service-Division: Paper machine condition analysis

Paper machines are designed for specific machines, for example in connection with these measurements are normally repeat- product types and defined output capac- project feasibility studies. ed for each product. The resultant data ities. They are also optimized for a and absolute pressure measurements are defined mechanical loading, both static used for assessing the approach flow lay- and dynamic. There is a growing demand out. In addition, various paper samples among operators for modernizing old 1. Condition analysis are taken in order to analyse the effect of paper machines as by means of measurements pressure pulsations on longitudinal and far as possible. The Before an old machine can be upgraded cross-machine profiles. goal is to achieve for higher output, mechanical loading better product limits have to be analysed above all. Even quality and greater for establishing new production param- output through eters and modifying the operating range 1.2 Mechanical vibration analysis higher operating of individual components – which can now A significant proportion of condition speeds. However, be done by computer methods – basic analysis investigations involves measur- before finalizing data is still essential. Extensive measure- ing mechanical vibrations on the paper the new production ments are often required in order to ana- machine itself. Measurements are first parameters a lyse existing operating conditions and carried out at highest possible operating machine condition possible improvement potential without speed on the headbox, wire and press analysis survey excessive modifications. sections and reel winder to assess vibra- The author: should be carried tions occurring during production. These Andreas Arnhold, out. By establish- basic readings initially indicate any dis- Measuring and ing the detailed turbances originating from shaker Diagnostics Service Ravensburg condition of the 1.1 Approach flow section analysis systems, drives, misaligned rolls or paper machine The starting point for condition analysis design deficiencies which might affect and its environment, conclusions can be is generally the approach flow section. To product quality or roll runnability. This drawn as to how far existing components ensure faultless product quality, the kind of investigation can also be carried can meet the new requirements. stock suspension and so the fibres out at any time to check and optimize flowing out of the headbox have to be machines for which no rebuild plans have distributed as uniformly as possible on yet been made. Who is better suited to carry out this the wire. Pressure pulsations originating task than reputed manufacturers of among other sources from rotating paper machinery? Not only are they machines in the approach flow section One of the main goals of condition analy- familiar with the needs of papermakers, play a decisive role in this. These pres- sis is to predict mechanical behaviour they also know all about the machine sure pulsations are therefore measured at at higher operating speeds. This means itself. several points between the cleaners and locating critical operating points or reso- headbox, using special sensors inserted nance conditions in the rolls, transmis- in the piping. A frequency analysis may sion and gear systems, framing and foun- Against the background of worldwide ref- then be carried out to detect the main dations. The mechanical behaviour of all erences, and together with the technical disturbances generated by the fan pumps machine sections is therefore analyzed at departments of the product divisions the or screeners. different speeds. Ideally, each group is engineers of the Voith Sulzer Paper Tech- accelerated to full speed several times in nology Service Division carry out condi- If various products with different basis succession in order to record dynamic tion analyses on all kind of paper weights are manufactured on the machine, characteristics over the entire speed Service 41

Fig. 1: Up to 16 sensors can be connected simultaneously to the multi-channel measuring system for data recording and analysis.

1 42

Fig. 2: Vibration measurements: An average of 100 measuring points are required for machine analysis from headbox to drying section on both front and drive sides.

Fig. 3: The measured frequency spectra are displayed in the form of waterfall diagrams as a function of machine operating speed. range. This can only be done by using a computerized multi-channel measuring system (Fig. 1) capable of reading data from up to 16 sensors at the same time.

It goes without saying that such meas- urements cannot be carried out during normal operation, but have to be sched- uled for long shut down periods. Carrying out this kind of vibrational analysis on an entire Fourdrinier machine, from headbox to the last drying section on both the drive and front sides, needs about 100 2 measuring points (Fig. 2) with a time outlay of 15 to 20 hours. The frequency spectra thus measured are displayed for each point as a function of machine speed in the form of waterfall diagrams

(Fig. 3). These indicate not only the 8 location of critical conditions, but also 6 any out of balance conditions in rolls, 800 etc. By carrying out a trend analysis 4 on amplitudes, the highest permissible 600 operating speed from the mechanical 2 ] Machine speed stress point of view can be determined. 0 400 [m/min Vibration velocity [mm/s] If necessary, these measurements are 0 20 40 60 80 100 complemented with numerical computer Frequency [Hz] 3 simulations. indicates whether larger rolls are acteristic, the hysteresis component can required at certain positions to allow for be determined and hence the friction in In addition to this, vibrational analyses higher operating speeds. the loading system. For example, by this are carried out on the guide rolls in the kind of measurement it was possible to wire, press and drying sections. Repre- locate a defective hydraulic cylinder. sentative rolls are selected in each sec- Additional nip impressions are also tion and tested for resonance beha- 1.3 Other analytical measurements evaluated at various line force settings, in viour using a special impact hammer Old machines often incorporate lever- order to assess line force profile unifor- (Fig. 4). Based on these findings, the type presses, whose actual pressing mity as well. critical speeds of these slender rolls can force is not usually known exactly. This be determined. In contrast to numerical data deficiency is remedied by using analysis, this experimental method estab- load cells which measure the pressing With modern computerized measuring lish the vibrational behaviour of guide forces transmitted via the supports. By techniques, the temperature profile over rolls under the installed condition. This recording a loading and unloading char- the web width can be determined using Service 43

Fig. 4: Selected rolls are tested for eigenfrequency behaviour using a special impact hammer.

Fig. 5: Thermographical measurements: Even the finished paper reel can be checked for uniform drying over the entire web width. special infra-red cameras. These thermo- graphical tests are mainly of interest in the drying section, but also in the press section, for assessing the web drying process. Usually damp zones are cooler than dry zones, so humidity profiles can be measured on the press felts but also on finished paper reels to assess unifor- mity of drying over machine width (Fig. 5). Here again, these measurements can be used for process optimization as well as condition analysis.

1.4 Air system analysis Air system measurements are carried out on supply and exhaust air in the drying section, in order to assess air and water balances. For this purpose sensor pockets have to be installed in the piping, upstream or downstream of the various branching points, for determining water and dry air flows. Likewise in the steam and condensate system, extensive meas- urements have to be carried out for assessing steam quantities, tempera- tures, pressures and flow velocities. 4 Based on this comprehensive data, con- clusions can be drawn for optimizing pip- ing layout and energy consumption.

2. Mechanical inspection Apart from pure measurements, a com- plete condition analysis also includes vis- ual inspection of the machine with regard to the bearing design of press rolls, guide-rolls and drying cylinders (Fig. 6). By also measuring bearing temperatures and oil flows, the existing lubrication system can be assessed with regard to 5 44

Figs 6, 7 and 8: Three important points for mechanical inspection: roll bearings, doctor moving systems and corrosion on all structural components. higher operating speeds. If a substantial speed increase is planned, grease lubri- cation may have to be replaced with an oil lubrication system, or high-tempera- ture grease must be used at least for the guide rolls in the drying section.

At this point our experts also assess the viability of existing pressing systems and doctor moving systems (Fig. 7). Finally, a rebuilt machine must be able to stand up to higher output without reducing run- nability. 6

At higher speeds long press levers are a disadvantage since they are prone to vibrate, for example, and fixed doctors are also unsuitable. Depending on the drive concept, gearwheels must be care- fully checked particularly in the drying section. Data in relation to this is avail- able from the vibration measurements carried out previously, since worn or damaged gear tooth flanks generate a special kind of vibration pattern. A visual check is still carried out on individual 7 gearwheels, however, and the clearance between mating gear teeth is measured. Furthermore open gearing makes more noise at higher speeds, which may not be tolerable.

Older plants must also be checked for corrosion, particularly in the wet section (wires and presses) where the wall thickness of structural components such as frames and levers may be seriously affected (see Fig. 8). For this reason the residual wall thickness at critical points must be carefully measured. These 8 Service 45

measurements are usually carried out by 5. Summary ultrasonic methods. Condition analysis serves not only for optimizing paper machinery, but also gives indispensable information on the 3. Electric motors and drives possibility of capacity increases, which Speed increases on old machines are normally mean higher operating speeds. often limited by existing drive and trans- Based on comprehensive measurements mission concepts. Even if individual and technically well-founded prognoses, drives are already installed, it may not be upgrading potential is assessed and any possible to increase motor capacity. critical components or weak points are Initially this can be checked by measur- located. Machine condition analyses are ing the motor current consumptions, nearly always a combination of extensive speeds and temperatures during normal measurements and visual inspection. operation, and comparing them with The most important criterion are the design data. In case where motor speed mechanical loading limits on the various is the limitation, the problem can usually components in each section of the be solved by using different gear ratios machine. These are mainly assessed by to keep the motor speeds within the vibration measurements, which are there- design range while increasing the speed fore an indispensable part of the analysis of the rolls. In cases of doubt Voith procedure. Sulzer may also consult the drive manu- facturer. These fundamental analyses are comple- mented by further investigations with a view to process optimization. Apart from 4. Vacuum system analysis purely mechanical inspection and meas- Increasing the machine output generally urements, Voith Sulzer, as an experienced means that vacuum requirements will be plant manufacturer, is also in the position higher for the suction rolls and devices in to assess the entire papermaking pro- the wire and press sections. Here again, cess. Apart from the approach flow sec- Voith Sulzer takes comprehensive meas- tion layout this covers the dimensioning urements of all vacua and flows involved of the vacuum system as well as of in order to analyze the vacuum system electrical and mechanical drives. A concept. The most important aspect comprehensive single-source service is here is to check vacuum pump capacities thus available which not only reveals versus design characteristics. This weak points but above all indicates shows whether the higher capacity can possibilities for optimizing machine run- be met by existing equipment or if new nability and improving productivity. pumps are required. Conclusions are also drawn with regard to the design of felt suction units (number and width of slots) and the interconnection of individual components. 46 Research and Development

1 47

Research and Development: The Voith Sulzer Paper Technology R&D centres

Since the founding of Voith Sulzer Paper Technology in 1994, group R&D capac- Voith Sulzer Paper Technology research and development facilities ities have been extended with additional facilities at various locations. According to the specialization of VSPT divisions, USA the working areas Germany at each research centre were like- wise re-defined. Parallel work at Brazil different locations has now been Working area Location eliminated, and the Stock preparation Ravensburg/Germany capacities thus Appleton, Wisconsin/USA freed are now con- Paper Machines centrated on spe- – Writings and printings Heidenheim/Germany cific research – Board and packaging Ravensburg/Germany – Tissue São Paulo/Brazil activities. As a Coating Technology Heidenheim/Germany The author: result, customers Finishing Krefeld/Germany A. Meinecke, now have special- Research Manchester/Great Britain and Development ists at their dispo- Winder Technology Heidenheim/Germany Heidenheim sal for solving problems in every area of paper technology, together with Heidenheim I A test coating machine with various the necessary test facilities and measur- At the Heidenheim research centre, devel- coating and equalization processes and ing systems. opment work is concentrated on paper a Speedsizer. Working width is up to production, ranging from headbox to 0.85 m and maximum speed is cur- sheet processing. This centre is also rently 2000 m/min. The primary goal of all VSPT R&D cen- responsible for research and develop- tres is to serve our customers. All our ment in printing and writing paper pro- I A trial roll cutting machine with vari- new developments and improvements in duction. Detailed development work is able geometrical configuration, for paper technology are directed at higher carried out on special facilities for each operation e.g. as two drum or as a one product quality, greater productivity and component, such as headboxes, sheet drum winder. more cost-effective paper machinery. formation and drying systems. The fol- lowing facilities are available for interre- lated process stage testing: Numerous development laboratories and This article presents the VSPT R&D cen- measuring facilities are likewise avail- tres and describes their work. In a later I For sheet formation and press trials, a able. edition of “twogether” we shall be report- total of four test paper machines with ing on research projects of particular various sheet formation and press con- interest (see table for summary of R&D cept configurations. These cover a facilities). speed range of 20 to 2000 m/min, with web widths of 0.5 and 1 m. 48

Fig. 1: (page 46) Heidenheim: pilot paper machine for printing and writing grades.

Fig. 2: Heidenheim: test coating machine.

Fig. 3: Heidenheim: test roll-cutting machine.

Fig. 4: Ravensburg: test paper machine for paperboard and packaging papers.

Fig. 5: Pilot paper machine for packing and board grades.

Ravensburg Research work in stock preparation is concentrated at this centre. Development of new and improved processes and machines – from pulping to bleaching – is carried out on numerous test facilities. The heart of the R&D facilities here is a stock preparation line which incorporates all the main process stages such as pulp- ing, screening and cleaning, flotation, disperging, refining, bleaching and thick- ening, including loop water treatment. Various complete stock preparation con- cepts or sub-processes can be tested here under mill conditions. Likewise cus- tomized stock preparation concepts can be studied and optimized. The extensive laboratory facilities ensure rapid evalua- tion of stock analyses and other meas- urements in the various process stages. 2

The Ravensburg test machine is particu- larly suitable for carrying out production trials on paperboard and packaging papers. Over a wide range of basis weights and operating speeds, single and multilayer or multi-ply papers and boards can be produced. In the press section adjoining the sheet formation section, various press configurations can be built up using the latest NipcoFlex technology. A great advantage is the close proximity of this machine to the stock preparation line, which allows stock made of special raw materials to be supplied under mill conditions for sheet formation trials.

3 Research and Development 49

4

5 50

Fig. 6: Krefeld: Finishing Division technology centre with soft nip calender.

Fig. 7: Krefeld: test calender for high surface finishing.

Fig. 8: Appleton, USA: technology centre mainly for waste paper recycling.

Fig. 9: Appleton, USA: test deinking plant with flotation cells.

Krefeld Here at the headquarters of the Finishing Division, R&D work is carried out on calendering. The main components of calenders are tested on special facilities, some of which are equipped with extremely high-resolution measuring systems. Sophisticated computer simula- tion programs are coming into general use for replacing or shortening some of the more time-consuming experimental work. For various calendering processes such as soft calendering or supercalen- dering, comprehensive facilities are avail- able which are fitted with the associated equipment for humidifying, preheating, etc. These allow calendering systems and parameters to be selected and optimized for customized requirements. The latest installation here is for carrying out tests 6 on the Janus concept. Other calendering test facilities are available for customer trials at Hunt & Moscrop in Manchester, England.

Appleton, Wis., USA The waste paper recycling quota is like- wise rising in North America – particular- ly for manufacturing printing and writing papers. For stock preparation tests, with special emphasis on waste paper, a com- plete line with all the various process stages is available in Appleton. These range from pulping, screening, cleaning and flotation to disperging, bleaching, thickening and loop water treatment. Tests and optimization trials can thus be carried out under mill conditions on near- ly all stock preparation processes. Stock can also be prepared from customers' 7 raw materials according to special Research and Development 51

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9 52

Fig. 10: São Paulo, Brazil: test paper machine for tissue grades with twin wire forming section and crepe cylinder.

requirements – in large quantities if nec- essary – for carrying out tests on produc- tion machines. Extensive laboratory facil- ities are available for evaluating test results.

São Paulo, Brazil This is the latest VSPT research and development centre, where a trial tissue machine with a working width of 1 m is installed. This machine incorporates the following modules: single or multilayer headbox, various twin wire configura- tions for sheet formation, a crepe cylin- der with presses and reeler. The machine is completed by a stock preparation line so that the effects of special raw materi- als on tissue quality can be investigated. An ambitious target here is the introduc- tion of new processing stages which will have significant effects on tissue produc- tion in future.

10 Corporate News 53

PAPER INDUSTRY PRESS CONFERENCE IN HEIDENHEIM

Workshop, symposium and cerned, information is every- birthday party: thing”.

At the end of September Does this joint venture 1995, international journalists between former competitors and German business press really work? Is the new com- leaders met in Heidenheim pany accepted on the market? at the first VSPT paper indus- What about the present situa- try press conference. The tion and future goals? The motto on this Voith Sulzer positive answers to all such questions impressed even the most experienced journalists – for the combined forces of this joint venture have brought some notable innova- tions which are making their mark among customers.

“The Voith Sulzer marriage in paper technology is working fine. The future looks promis-

Paper Technology anniversary was “twogether future for paper”.

The conference got off to a ceremonial start with a trumpet concerto in Abbey church – part of the Benedictine monastery’s ninth centennial celebrations. the Heidenheim engineering ing. Out of the red straight Hans Müller, President and centre to welcome guests after take-off. Unexpectedly CEO (seen above with Kevin from Australia, Singapore, the high order intake”… These Chang of Paper Asia) had USA and numerous European are only some of the head- every reason to be content: all countries. “For us the press – lines appearing after the 1995 the VIPs of international paper and above all the paper indus- VSPT press conference. And industry journalism were try press – is a very important everyone who attended this present on this memorable partner”, said Müller. “As far fertile round of discussion occasion. The entire VSPT as technical advances and wants to come back again management were gathered at customer benefit are con- next time. 54

BIBLIOPHILI TREASURES

Neresheim Abbey, only a few minutes’ drive from Heidenheim, was founded in 1095 and celebrates its ninth centennial this year. This monument to European cultural history houses a library with some twenty thousand medieval and early baroque volumes. Paper and Culture 55

In eastern Baden-Württemberg, at the brates its nine-hundredth anniversary. residence in Neresheim Abbey. Toward crossroads between Heidenheim and Founded in 1095 by Hartmann of the end of the Thirty Years’ War the Nördlingen, and Dillingen, lies Dillingen, the abbey has survived all the abbey became headquarters of the Swed- Neresheim – only a few minutes from the turmoil of European history. ish General Lorenz von Hofkirch. Würzburg-Ulm motorway. Already during the first struggle for pow- The same fate befell the abbey during the Whichever way you approach Neresheim, er between Kaiser and Curia, the abbey Coalition Wars of 1796 to 1801, when you will be surprised by an imposing col- was burnt down by Konrad IV, banished General Moreau set up headquarters for lection of buildings dominating the town son of the Hohenstaufen Kaiser Friedrich Napoleon’s troops in Neresheim. As if for from its 582 m.a.s.l. vantage point – the II, because its monks were loyal to the the sake of posterity, he nonchalantly Benedictine abbey. On a clear day the Pope. In 1525 the Peasants’ War raged recorded his daily log in the abbey library view from here extends to the Alpine over the Härtsfeld, and during the guest-book. peaks. This year Neresheim Abbey cele- Schmalkaidic War in 1546 Karl V took up 56

Two dozen incunabula still remaining Most important baroque church Despite all the losses inflicted by war and north of the Alps secularization, the abbey library still When Balthasar Neumann, born in 1687 houses many other treasures apart from of an Eger clothmaker, was approached its notable guest-book. It is one of the by Abbot Aurelius of Neresheim, he was very few baroque libraries in South Ger- already reputed to be the greatest archi- many whose form and content has tect between Cologne and Constance. His remained more or less intact over the creative intuition was combined with an centuries. As a highlight among almost enormous capacity for hard work and a twenty thousand volumes ranging from genial talent for organization. In his posi- the fifteenth to early nineteenth centuries tion as senior architect to the Archbishop 25 incunabula have been preserved here. of Würzburg, he was responsible for con- The relatively extensive collection as it struction works throughout the land as stands today was built up through well as for the building materials and systematic acquisition and exchange, or glass manufacturing plants which he thanks to foundations and donations. A himself had founded. As artillery colonel number of works were acquired as a kind he was responsible for military defence of “morning gift” from the mother house and engineering, artillery and fortifica- Beuron and other monasteries when the tions. And as engineer he held an impor- abbey was newly founded. Prince Albert tant teaching post in civil and military of Thurn and Taxis and his consort Mar- construction. At times Neumann was in garetha of Austria bequeathed the new charge of more than 10,000 workers dis- abbey a valuable collection of volumes, tributed among his various building sites. which are particularly interesting from With no telephone communications or the art history point of view. At the copying facilities and only horse trans- present time the entire collection is port, this seems an impossible task today housed in the so-called “new library”, – but as we can see, it was indeed pos- where another 85,000 volumes from sible. more recent times can be found. The library is not the only attraction, Neresheim represents the peak of The baroque wing of the monastery however. Neresheim Abbey is well worth Neumann’s achievements in ecclesiastical building, where the old library is situated, visiting as one of Europe’s most interest- architecture. At the height of his creative was in danger of collapse but in the ing and best-preserved baroque edifices. powers and in his best years, he incorpo- meantime has been saved by restructur- Construction of the present buildings rated in this building all the ideas inspir- ing measures. Interior restoration work is started in 1694 and took thirty years to ing his most important work. It is here still underway, with particular outlay complete, interrupted by wars and lack of that Balthasar Neumann expressed his required for the library room with its val- funds. sense of grandiose celebrity with the uable stucco ceilings. Thanks to gener- greatest perfection. The masterpiece of ous support from local firms, the Baden- The crowning glory is the abbey church baroque architecture we are privileged to Württemberg authorities and internation- designed by Germany’s most famous see and admire in Neresheim today is a al well-wishers, it is hoped to reopen the architect of the day, Balthasar Neumann true statement of timeless nobility. library in one or two years as a European of Würzburg who was also an artillery centre of learning. colonel. Paper and Culture 57