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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 expectfrom the ‘twogether company’?”. This comment by a reputedcustomer in the USA reflects the overwhelming response toour first edition of “twogether” magazine. Not only the paperindustry, but also professional associations, academic institutesand the trade journals were unanimous in this acclaim. Bearingin mind today’s flood of printed media and pressure of time, wewere delighted with such a positive response. And it is nice to becalled a “twogether company” – a sign of acceptance as partnerin the paper industry.

Keeping you up to date in this way is another step in our strategyof closer customer contact. What are the next steps? How willthe situation of papermakers and machinery manufacturersdevelop in the context of increasingly rapid global marketchanges? A dependable way of foretelling the future wouldcertainly be the dream of all investors.

Some weeks ago we received an interesting paper on this themeby Riccardo E. Moeschlin, an expert not unknown in the paperindustry. How valid are such forecasts? Since no recipe existsfor reliable prognoses, and as human beings we are all prone toerror, this theory based on repetitive economic cycles seemsparticularly interesting. Read on and judge for yourself!

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

Sincerely

Hans Müller

Hans Müller,President and CEO,Voith Sulzer Papiertechnik GmbH

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3Aus dem Unternehmen

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Aus dem Unternehmen

HIGHLIGHTS

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STARTUPS, ORDERS ON HAND

STARTUPS

Waste paper processing systemsand subsystems for printings andwritings945,000 tonnes p.a.

ANM Albury, AustraliaStora Feldmühle, Langerbrugge,BelgiumUtzenstorf Paper Mills, SwitzerlandHann. Paper Mills, Alfeld, GermanyStora Feldmühle, Kabel, GermanyMD Paper, GermanySCA Aylesford, Great BritainGeorgia Pacific, Kalamazoo, USA

Waste paper processing systemsand subsystems for board andpackaging papers550,000 tonnes p.a.

Visy Paper, AustraliaLenk Paper Mills, Kappelrodeck,GermanyTownsend & Hook Ltd, Snodland,Great BritainP.T. Indah Kiat, IndonesiaBoard AB, Fiskeby, SwedenHansol Paper, South KoreaShin Poong, South KoreaVisy Paper, Conyers, USA

Waste paper processing systemsand subsystems for tissue papers148,000 tonnes p.a.

Thrace, GreeceApizaco, Mexico

Stock preparation AS Sunland Eker Paper Mills,SwedenPope and Talbot, Wisconsin, USAScott, Owensboro, USA

Waste paper processing systemsand subsystems for other types ofpaper110,000 tonnes p.a.

Kemsley, UK Paper, Great BritainAuburn VPS, USA

Chemical pulp processing systemsMD Paper, Dachau, GermanyStora Billerud, Baienfurt, GermanyWeißenborn Paper Mills, Germany

264,000 tonnes p.a.

Printings and writingsTamil Nadu Newsprint and PapersLtd, Madras, India

Board and packaging papersVisy Paper, AustraliaWillamette Ind. Inc., USAHansol Paper Co. Ltd, Korea

RebuildsVisy Paper Conyers, USAHaindl Paper GmbH, Walsum,GermanyCartiere Burgo SpA, ItalyStora Billerud GmbH, Germany

Holmen Paper AB, SwedenHaindl Paper GmbH, Schongau,GermanyMD Paper GmbH, GermanyPWA Graphical Papers GmbH,GermanyAlbbruck Paper Mills, GermanyKanzan Spezialpapiere AG, GermanySmurfit Newsprint Co., USAStora Grycksbo AB, SwedenStora Langerbrugge N.V., BelgiumSteinbeis Temming, GermanyNorske Hönefoss, NorwayStora Feldmühle, Hillegossen,GermanyStora Forest Industries, Canada

Coating technologyVotorantim Celulose e Papel SimaoJacarei, BrazilKanzan Spezialpapiere GmbH,GermanyInternational Paper, PolandConsolidated Papers Inc., Biron Mill,USAMD Paper, GermanyAlbbruck Paper Mills, GermanyZaklady Celulozowa PapierniczeS.A., PolandSaica Zaragoza, SpainRipasa S.A. Celulose e Papel,Limeira, S.P., BrazilKostryznsie Zaklady PapiernieczeS.A., PolandScheufelen Paper Mills, Germany

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

Winding technology- DuoreelHaindl Paper GmbH, Walsum,Germany- WindersTamil Nadu Newsprint and PapersLtd., Madras, IndiaHaindl Paper GmbH, Schongau,GermanySmurfit Newsprint Corp., USAVisy Paper, AustraliaVisy Paper Conyers, USAKostryznsie Zaklady PapiernieczeS.A., Poland

SupercalendersBurgo Ardennes, BelgiumPTS, GermanyJiangnan Paper Mill, China

Soft calendersHenry Cooke Makin, Great BritainPap. de Gascogne, FranceNN, GermanyJang Chun, KoreaGeorgia Pacific, USAPortals, Great BritainShandong, ChinaHannover Paper, GermanyPap. Calparsoro, SpainLongview Fibre, USAInland Empire Spokane, USAVisy Board, AustraliaTai Shan, ChinaZhu Hai, ChinaSappi Specialities, Great Britain

Paper machines

Finishing

Companhia Suzano de Papel eCelulose, BrazilInternational Tendering CompanyCNTIC, China

SupercalendersKNP Leykam, NetherlandsYuen Foong Yu, TaiwanBosso, ItalyUPM Tervasaari, FinlandMarubeni for Daishowa, JapanHansol Paper, Korea

Soft calendersGenting Newsprint, MalaysiaCMPC Procart, ChileBallarshah, IndiaSiam Paper, ThailandPap. del Aralar, SpainMiliani f., HungaryAssi Domän, SwedenKymmene Wisaforest, FinlandSimao, BrazilHenry Cooke Makin, Great BritainIP Kwidzyn, PolandJ.R. Crompton, Great BritainPortals, Great BritainNingbo PM 3, ChinaNingbo PM 2, ChinaHalla Paper, KoreaHolmen Paper, Braviken Mill,SwedenSCA Ortviken, Sweden

Machine calendersAustralian Paper, AustraliaNingbo, ChinaTownsend & Hook Ltd, Great BritainCrown Packaging, CanadaSCA Ortviken, Sweden

RebuildsStora Kabel, GermanyStora Reisholz, GermanyCart. Toscolano, Italy

Roll transport systemsKNP Leykam, NetherlandsScheufelen Paper Mills, GermanyNDI, NetherlandsHalla Paper, KoreaGenting Newsprint, Malaysia

St. Petersburg Carton Combine, CISCorenso United Ltd, Finland

Chemical pulp processing systems597,000 tonnes p.a.

Neidenfels/Blue Star,Germany/ChinaTronchetti, ItalyHiang Seng, Thailand

Pulper feed systemsStora Feldmühle, BelgiumVPK Oudegem, BelgiumNingbo Zhonghua Paper, ChinaSt. Petersburg Carton Combine, CISCorenso United Ltd, Finland

3,198,000 tonnes p.a.

Printings and writingsConsolidated Papers, Stevens Point,USAHolmen Paper Mill, Braviken,SwedenSCA Ortviken AB, SwedenSinar Mas Pulp & Paper Ltd, IndiaHalla Paper Co. Ltd, KoreaMazandaran Wood and PaperIndustries, Iran

Board and packaging papersVisy Paper, USAZülpich Paper GmbH & Co. KG,GermanyVictorgo Industries Guangzhou,ChinaVPK Oudegem, BelgiumNingbo Zhonghua Paper Co. Ltd,ChinaThai Kraft Paper Industry Co. Ltd,ThailandVisy Paper, Brisbane, AustraliaMazandaran Wood and PaperIndustries, IranP.T. Indah Kiat, Pulp & Paper Corp.,IndonesiaCMPC-Cia. Manufacturera dePapeles y Cartones S.A., Chile

TissueBacraft, BrazilAl Keena Hygienic Papermill Co. Ltd,Jordan

Papelera De Castilla Duenas, SpainSam Poong, KoreaSuzano, BrazilPerlen paper Mills, SwitzerlandSNIA f. Krasnokamsk, RussiaLong You Paper, China

Machine calendersCrown Packaging, CanadaAustralian Paper Botany Mill, AustraliaZhu Hai, ChinaCrane Byron Mill, USA

Weyerhaeuser, USA

RebuildsArjo Wiggins, FranceKoehler, GermanyPudumjee, India

Roll transport systemsBruckmann, GermanyMaul Belser, GermanyBurgo Ardennes, BelgiumKNP Leykam, Netherlands

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ORDERS ON HAND

Waste paper processing systemsand subsystems for printings andwritings1,466,000 tonnes p.a.

Hermes Paper Mills, GermanyParenco B.V, NetherlandsTrust International Paper Corp.,PhilippinesHolmen Paper Mill, Braviken,SwedenAustralian Newsprint Mills, AustraliaJiangmen, ChinaStora Kabel GmbH, GermanyPaper Industries Corp., PhilippinesHalla Engineering & HeavyIndustries Ltd, South KoreaHansol Paper Co. Ltd, South KoreaGeorgia Pacific, USADae Han Paper, South KoreaGenting Newsprint Sdn. Bhd.,Malaysia

Waste paper processing systemsand subsystems for board andpackaging papers2,479,000 tonnes p.a.

Ningbo Zhonghua Paper, ChinaCMPC Procart, ChileZülpich Paper GmbH & Co. KG,GermanySCA De Hoop, NetherlandsVSDN Cape Kraft, South AfricaCheng Loong Co. Ltd., TaiwanThai Kraft Paper Industries Co. Ltd.,ThailandGeorgia Pacific, USAPort Townsend, USAPT Indah Kiat, Indonesia

Waste paper processing systemsand subsystems for tissue papers93,000 tonnes p.a.

A/S Sunland Eker/Papirfabrikken,NorwayCrisoba Industrial, Mexico

Waste paper processing systemsand subsystems for other types ofpaper478,000 tonnes p.a.

Australian Paper Manufacturers,Fairfield Mill, Australia

Tien Long Paper Mill, TaiwanIndustria Cartaria Tronchetti Burgo a Mozzano, Italy

RebuildsVisy Paper, AustraliaBataan Pulp and Paper Mills Inc.,PhilippinesCMPC, Santiago, ChileThomas Tait & Sons Ltd, Great BritainTentok paper Co. Ltd, JapanDavidson & Sons, Great BritainUnited Paper Mills Ltd, FinlandFederal Paperboard Co., USAConsolidated Paper Inc., USARigesa Celulose, Papel eEmbalagens Ltda, BrazilAssidoman Kraftliner, SwedenWestvaco Corporation, USAStone Container Corporation, USA

Coating technologyNippon Paper, JapanKoehler Paper Mills GmbH, GermanyFederal Paperboard Comp. Inc.,USASCA Ortviken AB, SwedenHansol Paper Co. Ltd, KoreaHalla Paper Co. Ltd, KoreaHong Won Paper, KoreaConsolidated Paper Inc. StevensPoint, USAKymi Paper Mill, Finland

Winding technology- DuoreelSCA Ortviken AB, SwedenKoehler Paper Mills GmbH, GermanyHolmen Paper AB, SwedenIndustria de Papel Arapoti SA, Brazil- WindersHalla Engineering & HeavyIndustries Ltd, KoreaPapeles Bio Bio SA, ChileHolmen Paper AB, SwedenGenting Newsprint Sdn. Bhd.,MalaysiaFabricadora de Papel de CeluloseS.A., BrazilTownsend & Hook Ltd, Great BritainGuangzhou Victorgo Industries Co.Ltd, China

Stock preparation

Paper machines

Finishing

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This recycling line with its trend-settingtechnology recently went into serviceafter more than two years of fruitful col-laboration with MD Papier GmbH. Tomeet specific requirements, convention-al recycling technologies were furtherdeveloped and adapted accordingly.Capacity of the new Plattling recyclingline is 72,000 t.p.a. of waste paperfurnish. Design services and machinerywere supplied by a consortium mainlycomprising Voith Sulzer Stock Prepara-tion GmbH, Ravensburg, B+G Förder-technik GmbH, Euskirchen, and Maschi-nenfabrik Andritz, Graz/Austria.

MD Papier GmbHhas invested 53million DM here ina recycling linewith almost en-tirely closed-cir-cuit water looplayout. This repre-sents a significantcontributiontoward increasingthe waste paperrecycling quota inGermany, a self-imposed obligationof paper producers

and publishers which was agreed inautumn 1994. Primary design criteria forthis recycling line were environmentalcompatibility and consistently high prod-uct quality. Thanks to completely newtechnological developments, it is nowpossible for the first time to use oldlabels from reutilized beer and beveragebottles as furnish for making high gradeprinting papers. This is done by efficientremoval of inks, stickies and wet-strength additives.

Previously, old labels of this kind weredisposed of in landfills or used as fillermaterial in the tile and brick industry,thus wasting the high-grade kraft pulp ofwhich they were made.

The so-called eco-agreement signed byMD Papier together with several brewer-ies creates the logistical conditionsrequired for label recycling. As a result,some 60,000 tonnes of bottle labels cir-culating every year in Germany can nowbe used as furnish for high grade pro-ducts.

The new recycling line – the first of itskind – makes this technically feasible byallowing the use of high wet-strengthlabels and punchings (special-grade

NEW PLANTS AND SYSTEMS

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

Raw materials treatment

Pulping

HC cleaning

Hole screening

Flotation

LC cleaning

Slot screening

Thickening

Disperging

Bleaching

Wet lap unit Storage

Stock processing line flow diagramfor standard waste paper

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waste paper) as well as higher-gradestandard furnish such as printing waste,returns and department store catalogues.

Depending on processing mode (specialor standard grade waste paper), the cor-rect machine sequence can be runaccordingly. The goal of this line conceptwas dual utilization of as many aggre-

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gates as possible in both modes. Dailycapacity is up to 220 tonnes of wastepaper.

Raw materials handlingWaste paper is delivered loose or inbales. The bales are automaticallydewired with a B+G Fördertechnikmachine, and fall as loose material on theslat conveyor pulper feed belt supplied bythe same company.

The integral weighing system stops the

conveyor automatically as soon as a pre-determined waste paper charge has beenfed to the pulper.

Pulping and HC cleaningThe waste paper is pulped at a stock con-sistency of 15-17% in an intermittenthigh-consistency pulper. This is designedfor maximum fibre retention and efficientdeinking.

All deinking additives are fed to the pulp-er together with each charge.

The pulper is drained via a PreCleansystem, which minimizes dumping timewhile at the same time ensuring consist-ent mixing of dilution water duringdumping. It also ensures efficient junkremoval.

The 2-stage PreClean system comprises aFiberizer with special rotor/screen combi-nation, a buffer tank and drum screen.Coarse rejects are removed at an earlystage by the Fiberizer hole-screen plate.Any fibres contained in the coarse rejectsare recovered in the drum screen before

, PRODUCT DEVELOPMENTS

Stock Preparation

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Fig. 1:Stock processing line flow diagram for standardwaste paper.

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

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they are dewatered and compacted in therejects screw press.

The pulp is pumped into one of three200 m3 dumping towers in order to ensureadequate fibre swelling and chemicalreaction of the deinking additives. Pulpleaving the dumping tower then passesthrough a high-consistency cleaner.

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

The first and second screening stagescomprise two Omnisorters for standardwaste paper, or two Fibersorters for spe-cial-grade WP. Coarse rejects areremoved in the third stage, which com-prises a Rejectsorter.

FlotationIn the flotation stage all the ink particlesand finely disperged impurities areremoved. This gives a consistently highquality recycled product which meets allrequirements for manufacturing printingpapers.

The flotation aggregate comprises fiveprimary deinking cells and one secondarycell. These closed-circuit cells arearranged in pairs, one above the other.Flotation air is injected into the stocksuspension through independently oper-ating step diffusors. Thanks to the highair content (up to 60%) and wide bubblespectrum, all ink particles from 10 to 500µm in size are removed. The closed-loop

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Fig. 3:Hole screening in the Fibersorter.

Fig. 4:Compact flotation cell.

flotation air circuit prevents polution ofthe atmosphere.

In the secondary cell any fibres stillusable are recovered. The sludge remain-ing is dewatered as far as possible in theprescreener before treatment in thesludge handling unit (supplied byMaschinenfabrik Andritz).

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

Rejects are treated with the sludge, whilethe accepts are processed for lightweight contrary removal.

In a 3-stage slotted screen system thesuspension is fine-screened again toremove mainly all the cubic rejects andstickies.

Thickening, disperging and bleachingThe clean suspension is now passedthrough a disk filter and afterwardsdewatered in a double wire press(supplied by Maschinenfabrik Andritz).This thickened stock is then conveyedby a screw system comprising shredder,elevator, feed and steam-heating screwsto a disperger with cast fillings. The dis-perging effect is based on the principle ofintensive friction between fibres. Thishomogenizes the stock and drasticallyreduces visible dirt specks. In order toincrease brightness, the stock isprocessed in a bleaching disperger withreductive additives.

Stock Preparation

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

Fig. 6:Disperger with heating screw.

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returned to the stock preparation processwater loop. The VarioSplit filtrate is like-wise cleaned by microflotation.

Rejects compactingCoarse rejects from the PreClean dump-ing system and hole screening are dewa-tered and compacted in a rejects screwpress.

Rejects from the high and low consisten-cy cleaners are transported by containerfor landfill disposal together with com-pacted rejects from the screw press.

Washing and wet lap systemFor processing special-grade waste paperfurnish, the stock is washed in a VarioSplit after low consistency slottedscreening. It is then processed in a wetlap unit and paletted ready for dispatch.

StorageAfter medium consistency bleach dis-perging, standard waste paper stock ispumped to a storage tower.

Water loopsThe water loops in this stock preparationline are almost entirely closed-circuit.Except for added dilution water andsealing water, no fresh water is used. Thesludge dewatering filtrates are purifiedby microflotation in a Purgomat, and

Fig. 7:Washing in the VarioSplit.

Fig. 8:View of storage tower.

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13Stock Preparation

Fig. 9:Water purification by Purgomat.

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According to an old saying: “paper ismade in the Holländer”. Despite the com-mon opinion that paper mills only containpaper machines, this still holds true – aslong as “Holländer” is replaced with“stock preparation”.

The task of stock preparation – the“factory” feedingthe paper machine– is to processbasic papermakingmaterials accord-ing to the requiredproduct grade andquality. Screeninghas always beenan important partof stock prepara-tion, and since therise of waste paperas a basic materi-al, it has becomeeven more impor-tant.

With traditional primary furnish such asgroundwood and chemical pulp, the com-ponents to be screened largely comprisesolid particles such as splinters. Withgreater use of recycled paper, the mainrequirement now is to remove softercomponents such as stickies, foils, sty-ropor and other rejects. This is muchmore difficult than screening out solidparticles.

The main importance of screening tech-nology lies not so much in the finishedpaper quality, but in the cost-effective-ness of the paper production and finish-

ing process as a whole – in other wordswhat goes into the paper machine at oneend, and how it is processed after itreaches the other end.

Screening machines today generallyoperate under pressure, and the pulp hasto be pumped into them (see Fig. 1).Inside the screen housing is a rotor anda fixed cylindrical screen basket. Thisis perforated either with holes or withslots.

Whether the screen basket has holesor slots depends on the kind of rejectsto be removed. The rule of thumb hereis to use holes for flat materials (suchas foils) and a slotted screen for cubicparticles (e.g. styropor). The idea is thatthe stock fibres should pass throughthe screen and the unwanted materialsshould remain for subsequent removal.

It is easy to see that apart from otherparameters, the main aspect here is thesize of screen hole or slot.

To meet today’s demands for clean stockdespite more use of dirty waste paper,very small screen holes or slots have tobe used – and the trend is more andmore toward fine slots.

Slotted screens are nothing new, but eversince the screen was invented theyhave played a secondary role. Slottedscreens in the past comprised flat platesin which slots were cut painstakingly

(Fig. 2). These were generally ≥0.8 mmwide, but for special applications slots assmall as 0.45 mm were used.

The limits of slotted screens were dictat-ed by manufacturing processes, whichallowed a relatively small amount of freescreening area, and by the low rotor effi-ciency due to the smooth surface. Boththese factors reduced throughput, so thatslotted screens were relatively uneco-nomical.

During the second half of the seventies,papermakers called more and more forgreater use of slotted screens and at thesame time for smaller slots. Screen man-ufacturing methods at that time did notallow either for modifying screen flowconditions or for increasing the freescreening area. The only possibilityremaining was to increase turbulence,and hence throughput, by adding bars tothe rotor side of the screener basket.

As a further development of these high-turbulence screener baskets, a widevariety of surface profiles were proposed.One example is the so-called VV basket(Fig. 4), comprising a large number of“minibars” generated by milled groovesin the basket surface. The principle herewas that the depth of these grooves influ-ences screening efficiency to a certainextent. In simple terms, a very rough sur-face increases throughput, while asmoother surface increases screeningefficiency.

All these screener basket versions had

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

The author:R. Rienecker, Product GroupScreening

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three drawbacks in common, however:the relatively small free screen area dueto manufacturing restrictions, the poorflow characteristics due to sharp slotedges, and last but not least the highmanufacturing cost.

Back in the nineteen-seventies Voiththerefore started developing smooth or bartype screener baskets, for which severalpatents were taken out (see Fig. 5). Thisdevelopment represented a quantum leapin screening technology at that time.

These baskets no longer had milled slotswith milled surfacing. Instead they haveprofile bars with an approximately trian-gular cross-section, spot-welded to stripswhich later form the stiffening rings onthe finished basket.

The slot width is defined by the bar spac-ing, while the bar angle generates thesurface profile. These flat screens arethen rolled into cylindrical form andwelded together into a finished screenbasket.

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

� Higher screening efficiency for thesame slot width

� No sharp edges� Large free screening area� Lower screening energy consumption

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.

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Stock Preparation

smooth bar type VV type

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rejects

accepts

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Direction of rotor rotation Directionof rotorrotation A

View A

Direction of rotor rotation Directionof rotorrotation A

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� Low-cost manufacturingThese fabricated screen baskets also havetheir manufacturing limits, however:

� Relatively wide scatter in slot width� Smallest slot size limited to about

0.2 mm since narrower slots requirethinner bars and reduce basket stability.

While retaining the bar-screen principle,these deficiencies were then completely

eliminated by developing and patentingan innovative manufacturing process.

All problems were solved through closecooperation between manufacturing spe-cialists and stock preparation experts,and the result is a mature screen basketmeeting all market requirements.

It is not easy for the layman to imaginehow many problems were involved indeveloping what seems at first sight to be

a plain and simple product.In order to comply with flow patterns,a screen basket is a highly filigranestructure. On the other hand it has towithstand extremely high dynamic loadsfor long periods in the screening ma-chine, and is often exposed to abrasiveattack as well.

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

On top of this, the use of chrome-nickelstainless steel turns the development ofsuch a screener basket into an engineer-ing challenge of the first magnitude.

The manufacturing process involves thefollowing main steps:

� Precise cutting of the clamping profilein the bars by laser technique

� Production of a flat screen by fittingspecially drawn profiled bars on anewly developed welding machine

� Rolling the flat screen into a cylinderand welding the ring ends together

� Machining the end flange and weldingit to the cylindrical screen

� Finish-machining the entire screenbasket.

Each of these manufacturing steps – par-ticularly welding and rolling – not onlydemands precise work planning but high-

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

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

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

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

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

� Bar-type basket without welding pointsin the screen structure

� Rings and bars shaped to clamp

together� Extremely close slot width tolerances� High uniformity and stability of slots in

the longitudinal direction due to close-ly spaced stiffening rings

� High surface quality (cold-drawn barswithout welding)

� 0.1 mm slot width easily reproducible� Large free screening area� Optimally variable profiling (no manu-

facturing limits).

Customer appreciation of these advantag-

es is shown by the fact that within ashort space of time about 700 C-barscreen baskets of various sizes (seeFig. 10) are now in service worldwide.And this trend is growing, since at thepresent time 6 fine screens in deinkingplants are entirely equipped with 0.15mm C-bar baskets, all with excellentresults in stickies removal.

Equally successful is the installation ofa 0.15 mm C-bar screen basket in theapproach flow section of a photographic

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

80%

70%

60%

50%

40%

30%

20%

10%

0≥ 0,15 0,2 0,25 0,3 ≥0,35 mm

C - bar-basket

Conv. bar-type

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Stock Preparation

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paper machine – a particularly demand-ing application. Likewise 0.1 mm C-barbaskets are now in service successfully,for example in an American waste paperstock preparation line and in an SC papermill, where the extremely fine slots andsuitable profiling has brought unsur-passed splinter removal efficiency.

An important point is that in many casesexisting screens cannot simply beupgraded with C-bar baskets. The operat-ing parameters have to be taken into con-sideration as well as the kind of screenand the system layout, etc. Above allwhen extremely fine slots are required,screen and system behaviour deviatesfrom experience with previous baskettypes.

C-bar baskets are currently in service forLC screening on waste paper stock pre-paration lines, for screening woody pulpand in approach-flow screening systems.They are soon to be used for mediumconsistency screening, and trials arealready underway.

New applications and the associatedproblems demand continuous develop-ment work on the C-bar basket, both

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.

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from the design point of view and withregard to manufacturing. By entering thishigh-tech field at an early date, VoithSulzer has acquired not only considerableknow-how in manufacturing C-bar bas-kets, but also wide background knowl-edge on their applications in the paperindustry. This allows fast reaction to newdemands.

Stock Preparation

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Close comparison of the two types withregard to technology, design and operat-ing principle brought the following find-ings:

The design advantages of the E-cell lie inthe cell unit and periphery (Fig. 1):

� Uncomplicated scale-up on a linearbasis

� No scale-up limitations (except pos-sible pumping limits)

� Simple level control by compensationbetween cells, i.e. only one level con-trol loop per stage

� Interior aeration element, particularlyadvantageous with closed-circuit pro-cess air loops.

On the other hand, the CF-cell also hastechnological advantages due to its moresophisticated injector design (Fig. 3).This results in an excellent efficiency inreducing a wide ink particle size range,particularly including large dirt specks.

Comparative testing on the Ravensburgpilot plant showed that for relatively easi-ly deinked waste papers (newspapers/magazines), both types of cell give equal-ly good technological results in theirstandard layouts.

For waste papers which are difficult todeink, such as mixed office waste, laser-print and multiprint, the CF-cell removeslarge ink particles (200-400 µm) consid-erably better than the E-cell (see Fig. 4).Based on these findings, it was decidedto use the E-cell for easily deinked waste

papers (newspapers/magazines) due toits design advantages in this respect,while for difficult waste papers such aslaser and multiprint, the more complextechnology of the CF-cell was justifiablebecause of its technological benefits.

The next step was obviously to try andcombine the advantages of both types. Avaluable basis for this was the thoroughresearch work carried out by SulzerPapertec on further development of thecompact flotation cell. It was found thatgreater efficiency particularly in dirtspeck removal could be reached mainlyby modifying the hydraulics of the airinjection element.

In this way the principle of the CF aera-tion element was transferred to themixing-bundle injector of the E-Cell.None of the existing design advantages ofthe E-cell were lost in this connection, infact they were improved. The air suctionhole of the E-cell injector was replaced byintake slots leaving almost the entireinjector periphery free, thus reducing thepossibility of air intake blockage.

As shown in Fig. 5, the comparative testscarried out on the new aeration elementprove the technological superiority of theEcoCell both for easily deinked wastepapers (newspapers/magazines) and dif-ficult grades such as laser and multiprint.

As a next step, these positive results willbe confirmed by practical trials on a flo-tation unit.

The new EcoCell combines the advantag-es of both existing Voith-Sulzer flotationcells – the E-cell and the Compact Flota-tion cell. These comprise on one hand thedesign features of the E-cell (simplecontrol strategy, practically unlimitedscale-up and inside aeration element),and on the other the technological bene-fits of the CF-cell (excellent efficiency inreducing a wide ink particle size range).

This has beenachieved by apply-ing the CF-cellaeration principleto the E-cell aera-tion element. Initialtests on a pilotplant have confir-med the outstand-ing efficiency of thenew Voith SulzerEcoCell, and thesewill now be fol-lowed by opera-tional trials in apaper mill.

After Sulzer Paper-tec and Voithjoined forces inpaper technology,one question was,which type of flo-tation cell shouldbe followed up asa joint Voith-Sul-zer product – theE-cell or the Com-pact Flotation cell(see Figs. 1 and 2).

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

The authors:T. Martin and H. Britz, product group Flotation

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Accept

Inlet

3-stage airaerationelement

Air

Foam

Step diffusor

Impack mixerDistri-butiondiffusor

Stock

Process air

Both cells withstandard aeration elements

500 1 2 3 4 5 6

Number of cells

52

54

56

58

60

62

64

66

Brig

htne

ss[%

ISO

]

Max. flotability limit

50% newspapers 50% magazines Stock consistency 1.1%

00 100 200 300 400

Particle size [µm]

20

40

60

80

100

Red

uctio

nin

Dir

tsp

eck

area

[%]

50% laserprint,50% multiprintStock consistency 1.1%, 4 cells

50

52

54

56

58

60

0 1 2 3 4 5 6Number of cells

62

Brig

htne

ss[%

ISO

]

Max. flotability limit

50% newspapers 50% magazines consistency 1,1%

00 100 200 300 400

Particle size [µm]

20

40

60

80

100

50% laserprint 50% multiprint Stock consistency 1.1%, 4 cells

E cellCFC cell

mixing-bundle injector

E cell EcoCell

new aeration element

Red

uctio

nin

Dir

tsp

eck

area

[%]

3

2

5

Stock Preparation

4

1

Fig. 1:Principle design of the Voith Sulzer E-cell.

Fig. 2:Principle design of the Voith Sulzer Compact Flotation cell (CF).

Fig. 3:Design of the aeration element of the Voith SulzerCF-cell.

With the EcoCell, a flotation cell will beavailable in future which optimally com-bines the advantages of both existingtypes.

Apart from further tests on the EcoCell,upgrading kits are being developed at thepresent time which will enable existingflotation units of (…) to benefit from thenew aeration technique (multi-injectortube cells or E-cells).

Inlet

Process Air

Foam

Accept

Fig. 4:Comparison of E-cell and CF-cell: test results.

Fig. 5:Technological comparison between the E-cell with mix-bundle injector and the EcoCell with new injector design.

21

pressure rises more gradually to ensureuniform compacting. In zone 3 the pres-sure falls off steeply to prevent rewetting.This kind of pressure characteristic isindispensable for gentle dewatering and auniform sheet structure with greatestpossible volume retention. Apart fromthis, pressure profiles with moderate gra-dients and low maxima also give longerfelt and sleeve life.

As backup to the NipcoFlex roll, theNipco-P roll shown schematically inFig. 5 combines the advantages of the

In 1984 the world's first closed shoepress went into service: the Voith Flexo-nip press. Two years later followed theSulzer Escher Wyss equivalent: the Inten-sa-S shoe press. Thanks to their highefficiency and outstanding technologicalresults, both systems soon became well-established (see Fig. 1). A total of26 Flexonip and 28 Intensa pressesare now in operation, mainly for brown

paper and paper-board production.Since Voith SulzerPaper Technologywas founded,orders have beenbooked for another15 Flexonip andIntensa shoepresses.

The joint venturebetween Voith andSulzer in papertechnology hasbrought a symbio-sis of the best

products from both sides. Based on morethan 200 years of accumulated operatingexperience with closed shoe presses, thegreater patent freedom now applying hasbeen exploited to unite the advantages ofboth concepts in a single product: theNipcoFlex press. This symbiosis is notlimited to the roll and shoe alone, butalso includes the backup roll – in otherwords, the entire press system (seeFig. 2). Since the market launching ofthis concept, ten NipcoFlex presses havealready been sold.

The new NipcoFlex roll shown in Fig. 3combines the shoe design of the Flexonip

press with the pressing system of theIntensa press. Pressed against the roll byindividual elements, the shoe is made upof an top and a bottom part which arethermally insulated from each other. As aresult, thermal deformations are largelyavoided. The shoe is asymmetrical to thepressing direction, displaced toward theingoing nip. The flexible roll sleeve islikewise asymmetrical to the pressingdirection, thus allowing a more favour-able sleeve intake geometry. Lubricationbetween the press shoe and roll sleeve ispurely hydrodynamic. To this purpose a

lubricating oil distribution pipe spreadscool oil uniformly over the sleeve imme-diately after the press nip, thus ensuringfreedom from wear. An added benefit ofthis single-source system is the above-average life of the yarn reinforced Quali-Flex press sleeves, a patented product ofVoith Sulzer Paper Technology.

As shown in Fig. 4, the shoe generates apressure profile with three characteristiczones. In zone 1 the pressure rise is rela-tively steep until the beginning of thedewatering phase (zone 2), during which

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

The author:W. Schuwerk, NipcoFlex Technology

1997

Num

ber

ofin

stal

latio

ns

0

10

20

30

40

50

60

70

80

1994199119881985

1

2

Flexonip Presse Nipco-Intensa-S-Presse NipcoFlex-Presse

22

classical Nipco roll with the stable bear-ing positioning of the profile roll. In factthe designation Nipco-P stands for “posi-tion-stable”. The roll bearings are spaceddirectly opposite the main roll bearings,and therefore unaffected by the inevitablebeam deflection. This brings someimportant advantages with regard topress operation. According to the well-proven Nipco principle, the roll shellrun on internal hydrostatic supportelements. As shown in Fig. 6, theseoperate on identical bearing surface areasin both rolls and are supplied withhydrostatic oil from a common feed pipe.This allows extremely simple and reliablecontrol, only one valve being required,and neither the roll bearings nor roll shellcan be damaged under any circum-stances. Only at the edges are smallcompensation elements required forpressure relief in case the web width ischanged.

One of the main reasons for the versatil-ity of the NipcoFlex press is its compactbearing frames (see Fig. 7). Thanks topatented link elements, mechanical forc-

es are transmitted directly from roll toroll without the need for massive sup-ports. This allows simple press designwith good accessibility, as well as fastfelt and sleeve changing.

So far shoe presses have mainly beenused on paperboard and packaging papermachines, and only now are they cominginto use for manufacturing wood contain-ing and wood-free printing papers.Operating experience with the world’sfirst shoe press on a newsprint machinehas shown that in this field as well, there

Zone l: Relatively steep pressure riseuntil dewateringZone ll: Flatter pressure rise duringdewateringZone lll: Steep pressure fall to preventrewetting

I II III

pres

sure

Time

is enormous potential for improvingdry content, output and product quality.By using a shoe press instead of aconventional third press, dry content wasincreased by 5% to 49-50% – despite a200 m/min speed rise to nearly 1200m/min – thanks to the sixfold increase inline force (see Fig. 8). This brought aproductivity rise of more than 16% with-out any reduction in specific volume,which was even increased slightly. Sheetsmoothness and 2-sided uniformity aftersoft calendering were improved at thesame time. The technological results and

cost-effectiveness of this concept havecomplied with all expectations.

For extremely high operating speeds,shoe press concepts with closed-loopweb runs are available. In mid-1996 theworld’s first 4-roll press with integralshoe press in the third nip is due to goon line in a 9.6 m wide newsprintmachine operating at 1800 m/min. Com-pared with existing concepts, the designof this Duo-Zentri NipcoFlex press (seeFig. 9) represents a real quantum jump.With dry content reaching 48% or more

5

4

Fig. 1: (page 21)Sales development of Voith and Sulzer shoe presses.

Fig. 2: (page 21)The symbiosis of Voith Sulzer shoe presses.

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 oildistributor, 8. Pressing element, 9. Press shoe.

Fig. 4:Ideal pressure profile.

Fig. 5:Longitudinal section through a Nipco-P roll:1. Bearing housing, 2. Roll sleeve,3. Support structure, 4. Pressure oil, 5. Pressing element, 6. Oil return, 7. Drive.

1

23

4

5

67

89

3

1 2 3 4 5 6 7

23

immediately after the press at an operat-ing speed of 1700 m/min, and a basisweight of 42 g/m2, productivity expecta-tions on this machine are high indeed.Another decisive advantage over conven-tional 4-roll presses is of course the highvolume retention during dewatering inthe last nip.

Before shoe presses come into generaluse for wood-free writing and printingpapers, a good deal of testing and oper-ating experience is still required. Thetrend is clear, however: not only do shoepresses bring the decisive advantages ofhigher dry content and greater productiv-ity, but in particular they also improveproduct quality. For these reasons shoepresses will soon be state-of-the-art forprinting and writing papers as well asboard and packaging products.

X

Pressure inhydrostaticelements

Systempressure

M

Nipco-P roll

NipcoFlex roll

PI

BA

P T

PI

End zone relief

6

7

Paper Machines

Fig. 6:Pressurizing system of a NipcoFlex press.

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

24

Before rebuild960 m/min

After rebuild1060 m/min

Dry content

Oil adsorption (COPB)

Before rebuild After rebuild

Newsprint 43 g/m2

15.618.3

15.7 17.2

Oil

adso

rptio

n(C

OPB

)[g

/m2 ]

30

20

10

RSTS RSTS

Dry

cont

ent[

%]

Before rebuild After rebuild

Newsprint 43 g/m2

44%

49%55

50

45

40

35

Specific volume

Before rebuild After rebuild

Newsprint 40 g/m2

Spec

ific

volu

me

[cm

3 /g] 3.0

2.0

1.0

1.67 1.68

PPS roughness

PPS

roug

hnes

s[µ

m]

3.1 3.1

3.33.4 After

calendering

Before rebuild After rebuild

RSTS RSTS

4.0

3.5

3.0

Newsprint 40 g/m2

8

9

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

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

Paper Machines

25

SummaryMachine operating speeds at the presenttime for producing printing paper are justover 1500 m/min on average, and newmachines are now being designed forspeeds up to 1800 m/min. Main require-ments on the drying section of these fast-running paper machines are high avail-ability and high specific evaporation

capacity, with min-imum energy out-lay for the productgrade in question.The Top DuoRunwith its overheaddryer aggregatesand DuoStabilizersmeets all theserequirements. Theweb is supportedthroughout theentire drying pro-cess, and in caseof a break wastematerial falls on aconveyor belt which

feeds it to the pulper. Thanks to shortdryer groups at the beginning and endof the drying section, longitudinal webstretch and lateral shrinkage are compen-sated so that folds and breaks are elimi-nated. The combination of DuoStabilizersand drilled guide-rolls fixes the web onthe dryer fabric, which not only stabilizesoperation in the dryer section but alsomakes for lower operating costs. Theropeless tail transfer system ensuressafe and reliable transfer through thedryer section, and an intermediate floorunderneath allows better space utiliza-tion. The DuoCleaner keeps the dryerfabric clean at all times, thus ensuringgood evaporation and reducing dirt con-

tent in the paper. In the V-Top DuoRun,the dryer section is arranged as a singleline in vee-form, thus shortening it byabout 20%.

IntroductionDuring the course of dryer section devel-opment, the bottom cylinder of a slalomdrying group was replaced by groovedguide rolls for the dryer fabric. This wasthe beginning of single-tier paper drying.In front of the run-in gusset between thegrooved roll and dryer fabric, a stabilizerhad to be installed to prevent web lift dueto air inclusions. This led to problems inthe edge zones of the web, where airinflow prevented fixing to the dryerfabric.

For high operating speeds, the groovedrolls were replaced with suction guide-rolls. These fix the web over its entirewidth to the dryer fabric and counteractcentrifugal force. The pre-suction zone ofthe roll, where the entrained air is suckedaway, replaces the web stabilizer.

Combi DuoRunThe Voith Sulzer Combi DuoRun is acombination of single-tier dryer group inthe first part, and double-tier dryer groupin the second part of the dryer section. Inmodern paper machines this conceptoperates successfully at speeds up to1500 m/min. With rising speeds, the num-ber of double-tier drying groups and thenumber of cylinders per group has beenreduced since problems were caused by

the damp web in the open draw of thedouble-tier dryer group. The dryer sectionof paper machine 11 in the Schwedt mills(Fig. 1) has six Top DuoRun groups, andat the end of the dryer section a double-tier group with six cylinders. This wasthe first paper machine in the world tohave only one double-tier drying group.The start up was in 1993 and nowoperates at more than 1500 m/min.

Top DuoRunThe latest generation of printing papermachinery is designed for operatingspeeds up to 1800 m/min. These highspeeds and much higher investmentcosts place more stringent requirementson the drying section:

� High runnability� High specific evaporation� Low energy consumption� High paper quality� Lowest possible investment costs

In order to meet all these requirements atsuch high operating speeds, Voith Sulzerdeveloped the Top DuoRun dryer sectionconcept described in the following.

The Top DuoRun (see Fig. 2) comprises asingle-tier dryer group with overheaddrying cylinders. Under the cylinders aredrilled guide-rolls, together with Duo-Stabilizers. Compact short dryer groupsare installed at the beginning and end ofthe drying section.

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

The author:M. Oechsle, Drying Technology

26

Due to the overhead tensioning of thedryer fabrics, the space under the single-tier dryer group is free. As shown inFig. 1, this was already utilized inSchwedt by installing an intermediatefloor for the waste conveyor belt. Theadditional basement space can be usedas roll and clothing store or for secon-dary aggregates. Not only is the cellar

enclosure smaller and less expensive, butbetter use is made of available space.

Main components of the Top DuoRunRising demands on paper quality makemachine cleanliness very important thesedays. For this reason all the drying cylin-

ders are equipped with fold-out doctorsto allow easy cleaning of the surfaces.The fabrics in the first dryer groupsare cleaned continuously by DuoCleanersduring operation.

All drying cylinders are dewatered by astationary suction siphon. The suction

1

2

Fig. 1:Combi DuoRun.

Fig. 2:Top DuoRun.

27

diameter as in the suction-roll, so that itcan be designed for low pressure losses.For these reasons smaller, lower-costfans can be used.

Comparison of electrical energy con-sumption shows that the DuoStabilizer/drilled roll combination uses about 70%less energy than a suction roll, and about60% less than the web stabilizer/groovedguide roll combination. Vacuum measure-ments on DuoStabilizers in productionmachines gave the following results:

In gap between outgoing wire and box 70-250 Pa

In dryer wire suctionguide roll 250-700 Pa

In gap between incoming wire and box 10-30 Pa

The use of DuoStabilizers allows the eva-poration distance between cylinders to beextended by up to 30%, without changingthe roll diameter.

The DuoCleaner (Fig. 4) is a fabric clean-ing device operated by water under highpressure. Dirt is removed mechanically,and the vacuum zone around the waternozzle sucks away the water and dirt par-ticles rebounding from the fabric.

The DuoCleaner operates at a pressure of200 to 300 bar and uses very little water

(about 0.7 litres/min). This means that itcan be used continuously throughoutproduction. Even at low basis weights,there is no visible interference in theweb. At the present time the DuoCleaneris used very successfully for basisweights between 35 and 160 g/m2. Itkeeps the dryer fabric clean and thushelps to improve water evaporation on theside of the web away from the cylinder.This increases drying capacity and reduc-es web curling. Installed on a testlinermachine, it was found that the DuoClean-er rapidly increased the air permeabilityof the dryer fabric from 270 to 375 cfm(new condition: 400 cfm).

Since shutdowns are not required forfabric cleaning, machine runability isimproved and these components soonpay for themselves.

siphon is ideal for fast-running machinessince it works independently of operatingspeed.

The ropeless tail transfer system isreliable and trouble-free. Tail removalfrom the cylinder surface and attachmentto the dryer fabric is assisted by air blownozzles. Transfer in the drying section viathe DuoStabilizer transfer zone and drilledroll is likewise assisted by air blowers.This system is simple and maintenance-friendly, and due to the short intermittentblower cycles air consumption is low. Atthe end of the dryer section the web issupported on the last drying cylinder, andcut by a water jet.

Together with the drilled guide roll, theDuoStabilizer sucks the web on to thedryer fabric and keeps it free of creases toallow reliable transport from roll to roll.The vacuum in the gap between outgoingfabric and box and in the fabric guide rollis provided by the DuoStabilizer, which isconnected to a vacuum system. The gapis sealed at the top of the DuoStabilizerby a felt seal across the web and by air-jets at the sides. The felt seal folds awayto allow changing of the dryer fabrics. Onthe operator side a transfer zone 500 mmlong is incorporated in the DuoStabilizerand drilled roll. During the transfer pro-cedure vacuum is applied to the transferzone only. The amount of air to besucked out in the DuoStabilizer is rela-tively small compared with the suctionguide-roll, since the felt seal keeps outthe air entrained with the fabric. Fur-thermore, the DuoStabilizer vacuum con-nection is not limited by the bearing

3

Fig. 3:Duostabilizer.

Paper Machines

28

Features of the Top DuoRun

Stable runningAfter leaving the last press nip, the webis sucked on to the fabric of the first dryergroup and fixed. It is then supported onthe fabrics right through the dryer sec-tion, thus ensuring stable running andreducing the risk of a break rupture to aminimum. The combination of DuoStabi-lizers and dryer fabric drilled guide rolltransports the web reliably from cylinderto cylinder.

At the cylinder runout point the DuoStabi-lizer fixes the web by suction on the dry-er fabric. The vacuum balances out thecentrifugal force around the drilled guideroll and thus keeps the web fixed to thedryer fabric.

Fig. 4:DuoCleaner fabric cleaning device.

4

High specific evaporationThanks to the high specific evaporation,dryer sections are shorter and invest-ment costs lower. To increase the heattransfer from steam to web, all cylindersare fitted with spoiler bars. In order toreach such a high evaporation capacity,the heated web must be able to dry outsufficiently after leaving the cylinder. Tothis purpose the DuoStabilizer provides along evaporation distance. Since most ofthe evaporation takes place below thecylinder in the Top DuoRun, hot air blowpipes are installed at this point. Theseblow pipes are dimensioned so that morefresh air is blown into the centre of themachine. The moist air then flows equallytoward the operator and drive sides ofthe machine, thus removing the watervapour on both sides to ensure a uniformhumidity profile.

High availabilityThe Top DuoRun ensures high availabili-ty, with short down times and consistent-ly high paper quality. Its stable run-ning characteristics reduce web breakfrequency to a minimum. A significantadvantage of this cylinder arrangement isthe short tear-off time required. Wastematerial falls on to the conveyor beltbelow and is transportet automatically tothe pulper. As a result, time-consumingremoval of waste from the drying sectionis no longer necessary. The ropelessedge strip transfer system ensures fastand reliable transfer, without any timewastage due to rope wear or breakage.

Controlled paper shrinkageDue to the rising web temperatures at thebeginning of the dryer section, the initialwet strength falls off and web extensionincreases. When the web is tensioned, itextends in the longitudinal direction andits width shrinks.

The DuoStabilizer fixes the web to thedryer fabric by suction at the cylindertake-off point. Relatively small forces arerequired 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 becompensated by speed adjustment, thuspreventing folds.

In single-tier dryer sections, the web isfirmly fixed to the dryer fabric and pre-vented from shrinking. This generatesweb stresses which can cause tearing. By

29

Fig. 5:V-Top DuoRun.

means of short dryer groups at the end ofthe dryer section, allowance can be madeby speed adjustments for web shrinkage,thus preventing breaks.

Prevention of curlingOne-sided drying makes the web tend tocurl. This curling tendency is caused inthe dryer section by unequal water dis-tribution between the top and reversesides of the web, which therefore curlstoward the most recently dried side.Tests on paper machines in practice haveshown that curling can be controlledquite precisely by adjusting side-to-sidehumidity distribution. This can either bedone in the drying section or afterwards.According to these tests, one-sided dry-ing has no effects on other paper charac-teristics.

The first Top DuoRun will start up inSweden early in 1996 on a newsprintmachine designed for an operating speedof 1800 m/min.

V-Top DuoRunThe V-Top DuoRun (see Fig. 5) wasdeveloped in order to minimize papermachine investment costs. It likewisecomprises a single-tier dryer section,but arranged in vee-form. At the begin-ning and end of the dryer section shorthorizontal dryer groups can be installed.The vee-configuration is more compactthan the horizontal arrangement, andallows more effective utilization of spacebelow the drying section.

The V-Top DuoRun is accessible fromseveral servicing levels. In case of webbreak, the waste material falls on to aconveyor belt below the machine. Withthe Vee configuration, drying capacitycan be increased without sacrificingspace, thus making it ideal for rebuilds.For the same number of drying cylinders,the vee configuration is about 20%shorter than the horizontal configuration.

5

Paper Machines

30

JetFlow F is the name of our new blade-coater generation. The new Voith Sulzerblade-coater was developed to maturity

in only threeyears, and is nowwell-proven inpractice. Withenormous poten-tial for output andproduct quality,the JetFlow F setsnew standards inthe paper industry.If we were toadopt Olympicsterminology, wecould say that theJetFlow goes fast-er, higher, furtherand cleaner – in

other words:� This coating machine runs faster

(better runnability) � Coating quality is higher than with

other types � It has wider applications than other

types � It uses jet-sizing – the cleanest way to

coat paper.

This article summarizes the developmentand technology of the JetFlow F. As shownby experience, the success of this newblade-coater is due to a complete under-standing of the principles and interrela-tionships involved.

1. Basic principleIn the early 1990s, a well-known USApaper producer had a good idea – todevelop a free jet coater for a predeter-mined coating thickness, evened out by ablade. This idea was not new, but it took

considerable brain-storming betweencustomers and engineers to make itfeasible. In order to put the idea down onpaper – literally – we converted our pilotmachine in Heidenheim accordingly.

2. DevelopmentAfter innumerable tests, rebuilds andoptimizations, the JetFlow F was finallyborn. Parameters such as jet angle,length, velocity and consistency for theright coating quantity and pressure wereworked out. A significant feature is thecurved outflow lip (patented) resultingfrom this development work. At the sametime a coating deaerator was developedfor this system which likewise improvesall other free jet coaters.

3. TrialsIn May 1993 the first two JetFlow F coat-ers were installed in the USA. Right from

The author:Bernhard Kohl,Application engineering coaters

Paper Machines Division:Coating with the JetFlow F

Tab. 1: JetFlow F Reference listwidth speed

Customer Coating system mm m/min Paper grades

Rapids 64 2 JetFlow F Off- 3680 1070 80-200 g/m2

USA CM single and double coating

Biron PM 24 1 JetFlow F On- 3680 762 LWC USA CM 60-80 g/m2

Plattling SM 11 2 JetFlow F Off- 7610 1550 LWCGermany CM 35-70 g/m2

Gratkorn SM 9 2 JetFlow F Off- 6450 1250 80-240 g/m2

Austria CM single and double coating

Kuusankoski PM 7 2 JetFlow F On- 4660 900 60-150 g/m2

Finland CM Precoating with Speedsizer

N.N. 2 JetFlow F On- 7680 1400 LWC + MWCFinland CM 6-16 g/m2

N.N. (LOI) 2 JetFlow F On- 7560 1500 LWCBrazil CM 40-70 g/m2

the outset, they met all quality demandsfor fine papers – although the coatingformulations used here had been devel-oped and optimized over some decadesfor roll-type coaters.

This was where the customer contribu-tion to development work really started.If the JetFlow F could meet roll-type coat-ing quality with these formulations, whatquality levels might it reach with formula-tions optimized for jet-sizing? – Better ones!

4. ResultsMany paper producers are interested inthe JetFlow F because they have prob-lems with their existing coaters. Exhaus-tive tests on the Heidenheim pilot coatingmachine have proved the versatility of theJetFlow F, and market acceptance is shownby the following reference list (Tab. 1).

31

5. Operating principleA thin coating film is applied in the formof a jet at a defined angle (Fig. 1). Airentrainment is prevented by the verticalforce component. Since the paper webmoves faster than the jet, the applicationarea is greatly extended. This makes thefilm much thinner and more uniform thanin conventional coaters, with the follow-ing benefits:� Better cross-profile� Lower blade loading� Smaller recirculation flow

In order to eliminate the air entrainmentproblem applying to all other types ofcoater, the coating jet is preceded by adeaeration unit (Fig. 3). In addition, thecurved outlet lip ensures centrifugal mix-ing of the coating material, so that by thetime it reaches the web it is completelyfree of air.

6. TechnologyThe JetFlow F induces no pressure pene-tration as in conventional coaters, butdewatering during the dwell time is unre-stricted and therefore more uniform. Fur-thermore, the coating material is moreliquid when it reaches the blade. Afterequalizing, the coating structure is thusbetter.

7. Clean operationThe JetFlow F is a closed system, andcoat reaches the paper without filmsplitting. As a result, coating takes placecleanly without any spray, mist or depos-its. Between the nozzle, blade and returnflow plate of an LWC coater, for example,a mirror-finish film without any stripescan be seen over a distance of 7 m

through the machine at 1500 mpm. Therange of applications tested so far onthe pilot machine is very wide (Tab. 2).Practical experience is not sufficient as

yet to assess overall potential, but basedon test results so far we are confident ofmeeting all market challenges.

2

Fig. 1: Schematic arrangement of the JetFlow F.

Fig. 2: JetFlow F coating principle.

Servicetank

Wash water

FS bypass

DS

Foam

pipe

Coating colour

Pump

Coating colour recovery

Pressure filterDeaerator

Tab. 2: JetFlow F Applications successfully tested

Raw paper:– wood-free 50 - 140 g/m2

– wood-containing 28 - 290 g/m2

Coat weight 4.5 - 17 g/m2

Speed range 330 - 1800 m/min

Solids content (4)50 - 70 %

Viscosity range (140)1200 - 2400 mPa · s(100 rpm Brookfield)

Paper Machines

1

32

For a number of uncoated and coatedpaper grades, softcalenders installedonline and offline are also currentlybeing used with success for calenderingin addition to the proven supercalen-

ders. The essen-tial challenges forthe future willbe improvementof the efficiencyof the manufactur-ing process withsimultaneouslyincreasing qualityrequirements. Theexperience avail-able for both pro-cesses results inthe necessity ofdeveloping com-pletely new calen-dering concepts tomeet these mar-ket requirements.

The following pro-vides a summaryof the argumentsdecisive for thedevelopment ofnew calenderingconcepts. Thetechnical and tech-nological possibil-ities of the newJanus Concept to

be installed online and offline are pre-sented. In comparison to the classicsupercalender, the exceptional advan-tages lie in online integration for eachproduction speed, the lower number ofrolls in conjunction with the use of plas-

tic covers, the distinctly lower calender-ing temperature compared with the soft-calender and the considerably lowerenergy requirement achieved as aresult.

Laboratory results will be discussedwith respect to a comparison betweenthe Janus Concept and supercalenderfor highly compressed paper applica-tions, i.e. LWC-Roto and SC-A, whichshow that the gloss and smoothnessvalues and printability for such papersare comparable with the current SC-finish, also for PM and SM speed.

IntroductionUntil the beginning of the 1980’s, calen-dering was carried out exclusively bymeans of supercalenders and machinecalenders. While the supercalender isdistinguished by its technological advan-tages due to the use of elastic rolls, the

advantages of the machine calender lie inits efficient operation, whereby the unit-ing of these two positive arguments werethe basis for the development of the soft-calender, which in meantime has estab-lished itself on the market.

Before dealing with the developments ofthe Janus Concept, a completely newcalendering technology, it is meaningfulto take stock between the supercalenderand the softcalender in order to clearlyshow the arguments decisive for the newprocess.

Table 1 initially shows the calender typeswhich could currently be considered for awide variety of papers, whereby the maindifference here lies in the higher numberof nips of 8-13 in the case of the super-calender, compared with 1-4 individuallycontrollable nips of the softcalender. Ifthese criteria are transferred to the calen-dering process, the supercalender isaccordingly provided with considerablymore nips for densification the paper via

The authors:U. Rothfuss,Janus Technology Centre,and U. Gabbusch, Development

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

Table 1: Comparison between supercalender and softcalender

Supercalender Softcalender

No. of nips 8 - 13 1 - 4

Cover material native fibre/plastic plastic

Cover hardness 85 - 91° ShD 85 - 94° ShD

Max. line load 350 N/mm 350 N/mm

Max. specific pressure 39 - 50 N/mm2 31 - 40 N/mm2

Max. surface temperature 100°C 200°C

Roll diameters smaller bigger

Load changes 2/revolution 1/revolution

Speed 450 - 900 m/min PM / SM speed

Table 3: Softcalender advantages/disadvantages

Advantages

Online installation possible

Individual controllable single nips

Minimisation of two-sidedness

Wide load and temperature range

High efficiency because of lessroll changes

For online installations low space requirement without add. personnel

Table 2: supercalender advantages/disadvantages

Advantages

Many nips with high degreeof coverage

Good distribution ofcalendering work betweenload and temperature

Process technically and techno-logically wellknown for decades

All paper grades can be finishedat high quality

Low amount of energy to be installed

Disadvantages

Not suitable for all paper grades

High amount of energy to be installed

Compression lines problem can occur

Only few nips

Finishing 33

pressure and temperature, while in thesoftcalender, a distinctly higher amountof energy has to be supplied for web den-sification per nip for a comparable calen-dering result.

Furthermore, it is important to show, onthe basis of Table 1, to what extent thetwo calendering processes additionallydiffer from each other (1).

The table clearly shows why higher calen-dering temperatures are necessary forthe softcalendering process. The largerroll dimensions are effecting a wider con-tact zone, which results in a lower com-pressive stress being produced based ona comparable line load compared with thesupercalender.

For a conversion energy comparable withthe supercalendering process, consider-ably higher surface temperatures areaccordingly necessary in the case of thesoftcalender.

An important point is the energy to beinstalled for both calendering processes.Based on a 8 metre wide plant, energyhas to be installed for a four-nip onlinecalender with about 50% more in com-parison to two offline 12-roll supercal-enders.

A further difference lies in the fact thatcovers made of cotton or a compositionof cotton and wool are still used to alarge extent in the supercalender, in con-trast to the softcalender, where only plas-tic covered rolls are provided. The advan-tages of the plastic covers are given bytheir higher mark resistance and a betterwear resistance, which finally serve to

Disadvantages

Limited speed range

Online installation not possible

Limited temperature range

Small influence onto two-sidedness

Low efficiency becauseof roll and reel change downtime

Dependence of line load fromtop to bottom nip

High space requirementwith additional

ensure a long life time. Cotton rolls bycontrast are subject to a higher mechani-cal load because of the double loadchange per revolution in the supercalend-

er, compared with the plastic covers inthe softcalender. The previously lowerloading capacity of the plastic coveredrolls is an argument which is currently

finish being produced which is compar-able to or better than a supercalender.

The task basically represents the totalsynergy between the supercalender andthe softcalender. Because of this doubletask, the concept was given the name ofthe ancient god with two faces: the JanusConcept. One face reflects tradition, thesupercalender and the softcalender, theother looks ahead towards new calendertechnology.

Table 4 Janus Concept requirements.

� Finish of all paper grades at high quality

� online and offline installationpossible

� High efficiency including less roll changes

� Low space requirement without add. personnel

� Low amount of energy to be installed

� Less energy loss during operation� Minimisation of two-sidedness� Wide load and temperature range

The core principle of the Janus Conceptis that only the number of nips necessaryfor calendering a specific paper quality isused. Missing nips, which are to beequated with mechanical conversionenergy, are not replaced by thermal ener-gy only. Based on the results of numer-ous analyses which showed that the highnumber of nips as used in the supercal-ender is unnecessary for the actual calen-dering process, a maximum of eight rollsresulted for the Janus Concept.

sidedness, due to individually controlla-ble single nips and the wide temperatureand line load range.

It should be mentioned that the success-ful use of the softcalender in the case ofspecific paper grades, e.g. high glossqualities, was initially made possible byengineering advances and the additionallycreated preconditions from the paper-makers. The latter mentioned includes, inaddition to levelling the cd-profiles, acoating formulation which has been con-sistently adjusted to the changed condi-tions of the softcalender.

The necessity to reconsider currentcalendering possibilities is also under-lined by the results of extensive testscarried out for a highly compressed SC-Apaper (3). The core statement here wasthat the printability of a SC-A paper,supercalendered with eleven nips, canalso be achieved with only four nips of asoftcalender when the temperatures ofthe chilled iron rolls reach minimum160°C and the compressive stresses ofall nips are in a range, as are present inthe bottom nip of a supercalender loadedwith 350 N/mm. However, this appliesonly to a speed range of about 500-700 m/min, i.e. the calendering speed ofthe supercalender usual for this type ofpaper.

The Janus ConceptDecisive for the development of a newcalender concept was the requirement foran online installation for any conceivableproduction speed in conjunction with a

34

still responsible for the main use ofcotton covers in supercalenders. How-ever, one cannot fail to notice that plasticcovers are increasingly being used insupercalenders, whereby their installationpositions are mainly in the upper calend-er area. In this connection, a technologi-cal aspect resulting from moving to plas-tic covers should not remain unnoticed.As a consequence of the internal friction,on account of their larger hysteresis, thecotton covers are subject to a highertemperature development, which issimultaneously a component of theconversion energy. In the case of plasticcovers by contrast, a clearly lower tem-perature development is noticed. Asupercalender equipped with such rollsproduces lower gloss and smoothnessvalues under comparable calenderingconditions as a result.

For the purpose of further clarification,the advantages and disadvantages ofboth calendering processes are shown inthe Tables 2 and 3 (2).

The list essentially shows that the super-calender cannot follow the currentspeeds of modern paper and coatingmachines. The capacity of the standardtwo supercalenders is frequently exceed-ed today. A second or third supercalend-er involves higher investment costs forbuildings and also add. personnel costs.The main features of the softcalender aresummarised in Table 3.

Summarised, the main advantages of thesoftcalender are its high efficiency andflexibility, whereby the latter mentionedfeature refers to minimisation of the two-

35

An initial precondition for online integra-tion of the Janus Concept is controllabil-ity of paper web threading at full PM orSM speed. Several years of intensivetests on a pilot plant, developed specifi-cally for this purpose, showed that webthreading can take place successfully bya combination of aerodynamic elementswith ropes and belts.

The most significant difficulties did notoccur at the beginning as actually expect-ed with web guidance within the calend-er, but rather with web transfer to thecalender. The control of problem-freeweb threading also assumes the drive ofall rolls installed in the calender.

Against the background of the finish,comparable with the supercalender inconjunction with minimum two-sided-ness, one solution could be the divisionof the supercalendering process into twoprocesses, represented by the twostacks, consisting of 5 rolls respectively.Additionally it was examined how a singlestage solution with 6-8 rolls could meetall requirements. Like the supercalender,a roll reversing nip must also be providedfor two-sided calendering. The two-sidedness can be controlled by influenc-ing the increase of line load nip by nip,using different roll materials and precal-culated nip widths.

The question naturally arises as to howthe energy plus of the Janus Concept isachieved compared with the supercalend-er, since the same result is to beachieved with less nips at a considerablyhigher calendering speed.

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

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

Fig. 3: Janus Concept: Formula.

1 2

Bulk

cm3 /

g

dwell time ms

com

pres

sive

stre

ssN/

mm

2

0.88

0.86

0.84

0.82

0.80

0.78

0.760.1 0.37 0.63 0.9

60

55

50

45100˚C150˚C

3

From the wide range of informationacquired from available supercalenders, amathematical description of the distribu-tion of the calendering work in the nipsof a calender could be found with the aidof extensive analyses.

Figure 3 shows the calendering range ofthe Janus Concept in three-dimensionalform. Illustrated in this case for the 8-rollversion, for example, is the bulk of aSC-A paper, applied to the Y-axis, as afunction of the dwell time, applied to theX-axis and compressive stress, applied tothe Z-axis. As curved surfaces in spacethe bulk at 100 and 150°C surface tem-perature can be seen.

This spatial representation is based onthe equation shown below which makes itpossible to predetermine the necessarycalendering temperature and compressivestress as a function of speed or dwelltime for any number of nips. In principle,this equation describes nothing else thanthe influence of these parameters on, e.g.the bulk of a paper. Equations can natu-rally also be used in a similar form forspecific gloss or smoothness values forthe respective customer product, i.e. forthe respective paper quality.

These calculations result, particularly inthe case of papers to be highly com-pressed, in necessary nip numberswhich a softcalender can normally notprovide.

In order to make this “multi-nip onlinecalendering process” possible, a wholeseries of technical elements are neces-sary. The most important features of theJanus Concept are accordingly listed inTable 5.

Finishing

bulk

[cm

3 /g]

≈1,

378

-0,0

0356

·T-(

0.00

825

-5,1

2·1

0-5

T)p

-[0,

039

+(0

,188

-0,0

0112

·T)p

·e-0

,093

p ]t·

e-0,

421t

Due to the considerably smaller rolls andhigh line loads compared with the soft-calender, compressive stresses up to60 N/mm2 can be realised in the JanusConcept, whereby the development ofsuitable plastic covered rolls took placeat the same time. The new roll generationwithstands the high mechanical and ther-mal loads whilst maintaining the familiaradvantages of low sensitivity to marksand high wear resistance, which ensuresa long life time.

Table 5: Janus Concept – Features

� High-speed open-nip threading system

� All rolls driven� New generation of plastic

covered rolls� Midrange-heated intermediate

rolls with new type of surfacetreatment

� Heated top and bottom roll� Individual temperature control

of all thermo-rolls� Lever-type calender with

overhanging load compensation

In addition to increasing the mechanicalconversion energy, the proportion ofthermal energy also had to be adapted tothe new concept. By using new types ofheat rolls, surface temperatures of about150°C with minimum cd-profile devia-tions are achieved. Each roll is allocateda separate temperature control loop. Theoil-heated deflection compensation rollsin the top and bottom position permitsurface temperatures of about 130°C,whereby each roll is similarly allocated

36

its own control loop. Thus, a total of fourcontrol elements are available for thermalreduction of two-sidedness.

The Janus Concept accordingly moves ina temperature level above the supercal-ender, however, distinctly below the tem-peratures necessary for the softcalender.In conjunction with the considerablysmaller roll diameters compared with thesoftcalender and utilization of thermalenergy of a heating roll in two nips, theheating capacity to be installed is drasti-cally reduced and the heat losses to theatmosphere are considerably reduced aswell. Table 6 shows the capacities to beinstalled, as well as the energy consump-tion of the Janus Concept in comparisonto an online 4-nip softcalender or two12-roll offline supercalenders for anassumed machine width of 8 m.

For the two calenders to be installedonline, the Janus Concept and soft-calender, an operating speed of 1200m/min at a design speed of 1400 m/min

was taken as a basis. For the supercal-ender an operating speed of 800 m/minrespectively at a design speed of 1000m/min was taken as a basis.

Assumed as maximum surface tempera-tures were 85°C for the supercalender,150°C for the Janus Concept and 200°Cfor the softcalender. The maximum lineloads are about 400 N/mm for the super-calender, about 550 N/mm for the JanusConcept and about 370 N/mm for thesoftcalender.

The table clearly shows that the JanusConcept has an approximately 15% lowerenergy requirement compared to twosupercalenders, and an approximately44% lower energy requirement comparedto the softcalender. The Janus Conceptalso has significant advantages for theenergies to be installed: 26% less thanthe supercalender and 45% less than thesoftcalender.

Further essential features of the JanusConcept are in the consistent realisation

Table 6: Energy balance Janus Concept – softcalender – supercalender

4-Nip Softcalender 2 Supercalender Janus Conceptinstalled consumed installed consumed installed consumed

Heatingcapacity 4320 KW 3140 KW 1950 KW 1300 KW 1860 KW 1430 KW

Drive power 3300 KW 2100 KW 2600 KW 1600 KW 2480 KW 1580 KW

Power for units 520 KW 400 KW 950 KW 440 KW 260 KW 140 KW

Power for winder 0 KW 0 KW 720 KW 360 KW 0 KW 0 KW

Total kW 8140 KW 5640 KW 6220 KW 3700 KW 4600 KW 3150 KW

37

of the constructive functional units ofthe new lever-type calender generationwith overhanging load compensation,which considerably improves the qualityof line load distribution in the individualnips.

In conjunction with the achieved weightreduction of 50% for the elastic rolls, theweight compensation distinctly increasesthe operating capacity of the Janus Con-cept. With comparable line load in thebottom nip, the overhanging load com-pensation and reduction of the rollweights as such enables a distinctly high-er line load in the above located nips, i.e.the line load characteristic from bottomto top becomes steeper. Figure 4 showsthe line load range of each individual nipof the Janus Concept in comparison to a

conventional calender or a compensatedcalender.

The steeper the line load characteristic,the less the line load differences arebetween the bottom and top nip, whichhas a positive effect on the reduction ofthe two-sidedness (4). Clearly distin-guishable is also the enormous line loadrange of the Janus Concept compared to

the relatively limited range of the super-calender.

The available high compressive stress,the steep line load characteristic, as wellas the temperature range up to 150°Cwhen using seven nips, create the pre-condition for calendering virtually allpaper grades at the respective PM andSM speed, based on the Janus Concept.

The test results achieved according to theJanus Concept with SC-A paper and LWCpaper for rotogravure printing are dis-cussed in the following. A laboratorycalender with all features of the JanusConcept will be commissioned in thesummer of this year and will be availablefor customer tests from autumn onwards.

Calendering of SC-A paper acc. to the Janus ConceptThe tests were carried out with a Europe-an standard SC-A paper. The basis weightwas about 56 g/m2, the ash content wasabout 31%. These papers are currentlybeing calendered with the addition ofsteam on two 12-roll supercalenders at250-280 N/mm line load and about70°C surface temperature at 650 m/min.

The following results show a comparisonof the standard supercalendering processto the Janus Concept, whereby in thecase of the Janus Concept, both the cur-rent calendering speed of 650 m/min aswell as the PM speed of 1000 m/min aretaken into account. Figure 5 initiallyshows the paper gloss according toGardner as a function of line load.

250 350

Line Load N/mm

JANUS CONCEPT: 120° C, 650 m/minJANUS CONCEPT: 120° C, 1000 m/minSupercalender: 70° C, 650 m/min

Glo

ssG

ardn

er%

550 250 350

54

450

5148454239363330

5

79

250 350

Line Load N/mm

JANUS CONCEPT: 120° C, 650 m/minJANUS CONCEPT: 120° C, 1000 m/minSupercalender: 70° C, 650 m/min

Prin

tglo

ssG

ardn

er%

450 550

7673706764615855

250 350

6

Fig. 4: Line load characteristic of the Janus Concept incomparison to a conventional or compensatedcalender.

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

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

1

3

5

7

9

0 50 100

Line Load N/mm

conventional Supercalendercompensated SupercalenderJANUS CONCEPT

Num

bero

fNip

s

11 150 200 250 300 350 400

4

One can see that the gloss of the papersupercalendered at 650 m/min is exceed-ed by the Janus Concept even at a PMspeed of 1000 m/min at 120°C surfacetemperature and line loads of about350 N/mm. The calendering temperaturewhich is 50°C higher compared to thesupercalendering process, has a stronglypositive effect on the gloss result in thiscase. Figure 6 appropriately shows theprint gloss of samples printed by therotogravure process.

For the print gloss, virtually the samecorrelations can be seen as previouslydiscussed for the paper gloss. At350 N/mm line load, the print gloss ofpaper supercalendered at 650 m/min canbe exceeded, even at a PM speed of1000 m/min. Figure 7 shows the rough-ness PPS-10 S over the line load.

Finishing

250 350

Line Load N/mm

JANUS CONCEPT: 120° C, 650 m/minJANUS CONCEPT: 120° C, 1000 m/minSupercalender 70° C, 650 m/min

Rou

ghne

ssPP

S-10

Sµ

m

1.0 550 250 350

1.1

1.2

1.3

1.4

1.5

450

7

38

The diagram clearly shows that theroughness of the supercalendered com-parison paper by means of the JanusConcept could be achieved at a compar-able calendering speed of 650 m/min atline loads of about 450 N/mm. However,due to the surface temperature of only120°C in this case, this was not com-pletely possible at a PM speed of 1000m/min. Figure 8 shows the densificationor bulk as a function of line load.

One can see that the compression of thesupercalendered paper by the Janus Con-cept at 450 N/mm line load is alsoachieved at a PM speed of 1000 m/min.Based on knowledge from earlier teststhat the printability of such paper wasless correlated with smoothness orroughness rather than with densification,a comparable printability was also to beexpected in this case (5).

The respective rotogravure tests carriedout confirmed this in all respects. Bothfrom a visual assessment aspect and alsofrom the number of counted missing-dotsin the quarter-tone range, no differencesof the supercalendered paper to theJanus Concept calendered samples wereto be seen.

A further important criterion, particularlyin the case of SC-A papers, is the so-called blackening. Blackening occurs withhigh densification of the papers due tocollapsing of the fibres. These fibres thenappear transparent in transmitted lightand black in reflected light.With the aid ofan image analysis system developed atthe Technical University in Darmstadt, itwas possible to measure the blackeningin the form of a blackening-index, where-by the larger percentage figure indicatesmore blackening. The respective resultsare summarised in Figure 9.

One can clearly see that the blackeningindex is lower in the case of paperscalendered according to the Janus Con-cept. This means that the Janus Conceptenables paper to be calendered with a

printability comparable to that of SCpaper with less blackening.

Summarised, this test shows that theJanus Concept is capable of producingwith only seven nips at maximum450 N/mm line load, even at PM speed,a paper with a printability comparableto that of the supercalender with lessblackening and a simultaneously higherprint gloss.

Calendering of LWC-rotogravure paperaccording to the Janus ConceptThe tests were carried out with a Europe-an standard LWC rotogravure paper. Thebasis weight was about 58 g/m2 the coat-ing weight was about 9 g/m2 per side.The papers are currently being calen-dered on two 12-roll supercalenders at270-300 N/mm line load and about 65°Csurface temperature at 700 m/min.

The following results show a comparisonof the standard supercalendering processto the Janus Concept, whereby in thecase of the Janus Concept, both thecurrent calendering speed of 700 m/minas well as the coater speed of 1400m/min are taken into account. Figure 10initially shows the paper gloss Gardneras a function of line load. One can seethat the gloss of the paper supercalen-dered at 700 m/min is exceeded by theJanus Concept also at an SM speed of1400 m/min, 135°C surface temperatureand 350 N/mm line load.

Figure 11 appropriately shows thesmoothness Bekk. The diagram clearly

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.

250 350

Line Load N/mm

JANUS CONCEPT: 120° C, 650 m/minJANUS CONCEPT: 120° C, 1000 m/minSupercalender: 70° C, 650 m/min

Bulk

cm3 /

g

550 250 350

0.86

450

0.84

0.82

0.80

0.78

0.76

8

250 350

JANUS CONCEPT: 120° C, 650 m/minJANUS CONCEPT: 120° C, 1000 m/minSupercalender: 70° C, 650 m/min

Blac

keni

ngIn

dex

%

550 250 350

60

450

58565452504846444240

Line Load N/mm

9

39

shows that the Bekk smoothness of thesupercalendered paper by the JanusConcept at double the speed of1400 m/min at 135°C surface tempera-ture and 350 N/mm line load is virtuallyreached and already exceeded at450 N/mm line load.

Figure 12 shows for the sake of com-pleteness also the roughness. Measuredaccording to PPS-10 S, the roughness ofthe paper supercalendered at 700 m/minby the Janus Concept at 1400 m/min and135°C surface temperature is alreadyexceeded at line loads of 350 N/mm.

Figure 13 finally shows the densificationor bulk as a function of line load. The dia-gram clearly shows that the bulk of thepaper supercalendered at 700 m/min cor-responds to the sample calenderedaccording to the Janus Concept at 1400m/min, 135°C surface temperature and

350 N/mm line load, i.e. calendering con-ditions under which more favourablegloss and roughness values could beachieved by the Janus Concept.

The rotogravure printing tests carried outfor this comparison showed, as was

already to be expectedfrom the calender-ing results, no differences in the print-ability of the samples supercalendered at700 m/min to the samples calenderedaccording to the Janus Concept at1400 m/min, whereby the latter werecharacterised by a higher print glossdue to the higher calendering tempera-ture.

Summarised, this test also shows thatthe Janus Concept is capable of produc-ing with only seven nips but double thespeed at 350-450 N/mm and 135°C sur-face temperature, a paper which is abso-lutely comparable with the supercalen-dering process. Both these tests basedon the example of the highly densifiedpaper grades, SC-A and LWC rotogra-vure, impressively show the enormouspotential of the Janus Concept.

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.

250 350

JANUS CONCEPT: 135° C, 700 m/minJANUS CONCEPT: 135° C, 1400 m/minSupercalender: 65° C, 700 m/min

Glo

ssG

ardn

er%

550 250 350

70

450

67646158555249464340

Line Load N/mm

10

250 350

JANUS CONCEPT: 135° C, 700 m/minJANUS CONCEPT: 135° C, 1400 m/minSupercalender: 65° C, 700 m/min

Smoo

thne

ssBe

kks

550 250 350

4000

450

Line Load N/mm

3500

3000

2500

2000

1500

1000

11

250 350

Line Load N/mm

JANUS CONCEPT: 135° C, 700 m/minJANUS CONCEPT: 135° C, 1400 m/minSupercalender: 65° C, 700 m/min

Rou

ghne

ssPP

S-10

Sµ

m

550 250 350

0.85

450

0.80

0.75

0.70

0.65

0.60

12

With this new calendering technology,papermakers are provided with an instru-ment which fully meets the initially men-tioned requirements for calendering highquality papers in “supercalender quality”also at PM or SM speed with highefficiency and distinctly reduced energyconsumption.

250 350

Line Load N/mm

JANUS CONCEPT: 135° C, 700 m/minJANUS CONCEPT: 135° C, 1400 m/minSupercalender: 65° C, 700 m/min

Bulk

cm3 /

g

550 250 350

0.86

450

0.840.820.80

0.74

0.70

0.780.76

0.72

13

Finishing

References

(1) Rothfuss, U. – A review of surface characteristics andprinting results from soft and supercalendered papers. TAPPIFinishing Conference, Chicago 1994

(2) Marleaux, H.P., Cramer,D., Kathan, C. – Von Matt bisHochglanz – Praxiserfahrungen mit On-/Offline-Softkalandernfür gestrichene Papiere. Wochenblatt für Papierfabrikation122 (1994), Nr. 8, 296 – 301

(3) Rothfuss, U. – Inline- und Offline-Satinage von holzhalti-gen, tiefdruckfähigen Naturpapieren. Wochenblatt für Papier-fabrikation 121 (1993), Nr. 11/12, 457 – 466

(4) Bresser, H., Kayser, F. – SNC – Der Superkalander der90er Jahre. Das Papier 43 (1989), Heft 10A, 169 – 182

(5) Dr. Lesiak, M., Rothfuss, U. – Online-Satinage von altpa-pierhaltigen SC-Papieren. 25. EUCEPA Conference, Wien 1993

40

Paper machines are designed for specificproduct types and defined output capac-ities. They are also optimized for adefined mechanical loading, both staticand dynamic. There is a growing demandamong operators for modernizing old

paper machines asfar as possible. Thegoal is to achievebetter productquality and greateroutput throughhigher operatingspeeds. However,before finalizingthe new productionparameters amachine conditionanalysis surveyshould be carriedout. By establish-ing the detailedcondition of thepaper machine

and its environment, conclusions can bedrawn as to how far existing componentscan meet the new requirements.

Who is better suited to carry out thistask than reputed manufacturers ofpaper machinery? Not only are theyfamiliar with the needs of papermakers,they also know all about the machineitself.

Against the background of worldwide ref-erences, and together with the technicaldepartments of the product divisions theengineers of the Voith Sulzer Paper Tech-nology Service Division carry out condi-tion analyses on all kind of paper

machines, for example in connection withproject feasibility studies.

1. Condition analysis by means of measurementsBefore an old machine can be upgradedfor higher output, mechanical loadinglimits have to be analysed above all. Evenfor establishing new production param-eters and modifying the operating rangeof individual components – which can nowbe done by computer methods – basicdata is still essential. Extensive measure-ments are often required in order to ana-lyse existing operating conditions andpossible improvement potential withoutexcessive modifications.

1.1 Approach flow section analysisThe starting point for condition analysisis generally the approach flow section. Toensure faultless product quality, thestock suspension and so the fibresflowing out of the headbox have to bedistributed as uniformly as possible onthe wire. Pressure pulsations originatingamong other sources from rotatingmachines in the approach flow sectionplay a decisive role in this. These pres-sure pulsations are therefore measured atseveral points between the cleaners andheadbox, using special sensors insertedin the piping. A frequency analysis maythen be carried out to detect the maindisturbances generated by the fan pumpsor screeners.

If various products with different basisweights are manufactured on the machine,

these measurements are normally repeat-ed for each product. The resultant dataand absolute pressure measurements areused for assessing the approach flow lay-out. In addition, various paper samplesare taken in order to analyse the effect ofpressure pulsations on longitudinal andcross-machine profiles.

1.2 Mechanical vibration analysisA significant proportion of conditionanalysis investigations involves measur-ing mechanical vibrations on the papermachine itself. Measurements are firstcarried out at highest possible operatingspeed on the headbox, wire and presssections and reel winder to assess vibra-tions occurring during production. Thesebasic readings initially indicate any dis-turbances originating from shakersystems, drives, misaligned rolls ordesign deficiencies which might affectproduct quality or roll runnability. Thiskind of investigation can also be carriedout at any time to check and optimizemachines for which no rebuild plans haveyet been made.

One of the main goals of condition analy-sis is to predict mechanical behaviourat higher operating speeds. This meanslocating critical operating points or reso-nance conditions in the rolls, transmis-sion and gear systems, framing and foun-dations. The mechanical behaviour of allmachine sections is therefore analyzed atdifferent speeds. Ideally, each group isaccelerated to full speed several times insuccession in order to record dynamiccharacteristics over the entire speed

Service-Division:Paper machine condition analysis

The author:Andreas Arnhold,Measuring and Diagnostics ServiceRavensburg

41

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

Service

1

42

range. This can only be done by usinga computerized multi-channel measuringsystem (Fig. 1) capable of reading datafrom up to 16 sensors at the same time.

It goes without saying that such meas-urements cannot be carried out duringnormal operation, but have to be sched-uled for long shut down periods. Carryingout this kind of vibrational analysis on anentire Fourdrinier machine, from headboxto the last drying section on both thedrive and front sides, needs about 100measuring points (Fig. 2) with a timeoutlay of 15 to 20 hours. The frequencyspectra thus measured are displayed foreach point as a function of machinespeed in the form of waterfall diagrams(Fig. 3). These indicate not only thelocation of critical conditions, but alsoany out of balance conditions in rolls,etc. By carrying out a trend analysison amplitudes, the highest permissibleoperating speed from the mechanicalstress point of view can be determined.If necessary, these measurements arecomplemented with numerical computersimulations.

In addition to this, vibrational analysesare carried out on the guide rolls in thewire, press and drying sections. Repre-sentative rolls are selected in each sec-tion and tested for resonance beha-viour using a special impact hammer(Fig. 4). Based on these findings, thecritical speeds of these slender rolls canbe determined. In contrast to numericalanalysis, this experimental method estab-lish the vibrational behaviour of guiderolls under the installed condition. This

indicates whether larger rolls arerequired at certain positions to allow forhigher operating speeds.

1.3 Other analytical measurementsOld machines often incorporate lever-type presses, whose actual pressingforce is not usually known exactly. Thisdata deficiency is remedied by usingload cells which measure the pressingforces transmitted via the supports. Byrecording a loading and unloading char-

acteristic, the hysteresis component canbe determined and hence the friction inthe loading system. For example, by thiskind of measurement it was possible tolocate a defective hydraulic cylinder.Additional nip impressions are alsoevaluated at various line force settings, inorder to assess line force profile unifor-mity as well.

With modern computerized measuringtechniques, the temperature profile overthe web width can be determined using

Fig. 2:Vibration measurements:An average of 100 measuring points are requiredfor 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 ofmachine operating speed.

2

88

6

4

2

00 20 40 60 80 100

400

600

800

Vibr

atio

nve

loci

ty[m

m/s

]

Frequency [Hz]

Machine speed

[m/m

in]

3

43

special infra-red cameras. These thermo-graphical tests are mainly of interest inthe drying section, but also in the presssection, for assessing the web dryingprocess. Usually damp zones are coolerthan dry zones, so humidity profiles canbe measured on the press felts but alsoon finished paper reels to assess unifor-mity of drying over machine width(Fig. 5). Here again, these measurementscan be used for process optimization aswell as condition analysis.

1.4 Air system analysisAir system measurements are carried outon supply and exhaust air in the dryingsection, in order to assess air and waterbalances. For this purpose sensor pocketshave to be installed in the piping,upstream or downstream of the variousbranching points, for determining waterand dry air flows. Likewise in the steamand condensate system, extensive meas-urements have to be carried out forassessing steam quantities, tempera-tures, pressures and flow velocities.Based on this comprehensive data, con-clusions can be drawn for optimizing pip-ing layout and energy consumption.

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

4

5

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.

Service

44

higher operating speeds. If a substantialspeed increase is planned, grease lubri-cation may have to be replaced with anoil lubrication system, or high-tempera-ture grease must be used at least for theguide rolls in the drying section.

At this point our experts also assess theviability of existing pressing systems anddoctor moving systems (Fig. 7). Finally, arebuilt machine must be able to stand upto higher output without reducing run-nability.

At higher speeds long press levers are adisadvantage since they are prone tovibrate, for example, and fixed doctorsare also unsuitable. Depending on thedrive concept, gearwheels must be care-fully checked particularly in the dryingsection. Data in relation to this is avail-able from the vibration measurementscarried out previously, since worn ordamaged gear tooth flanks generate aspecial kind of vibration pattern. A visualcheck is still carried out on individualgearwheels, however, and the clearancebetween mating gear teeth is measured.Furthermore open gearing makes morenoise at higher speeds, which may not betolerable.

Older plants must also be checked forcorrosion, particularly in the wet section(wires and presses) where the wallthickness of structural components suchas frames and levers may be seriouslyaffected (see Fig. 8). For this reason theresidual wall thickness at critical pointsmust be carefully measured. These

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7

8

Figs 6, 7 and 8:Three important points for mechanical inspection:roll bearings, doctor moving systems and corrosion on all structural components.

45

5. SummaryCondition analysis serves not only foroptimizing paper machinery, but alsogives indispensable information on thepossibility of capacity increases, whichnormally mean higher operating speeds.Based on comprehensive measurementsand technically well-founded prognoses,upgrading potential is assessed and anycritical components or weak points arelocated. Machine condition analyses arenearly always a combination of extensivemeasurements and visual inspection.The most important criterion are themechanical loading limits on the variouscomponents in each section of themachine. These are mainly assessed byvibration measurements, which are there-fore an indispensable part of the analysisprocedure.

These fundamental analyses are comple-mented by further investigations with aview to process optimization. Apart frompurely mechanical inspection and meas-urements, Voith Sulzer, as an experiencedplant manufacturer, is also in the positionto assess the entire papermaking pro-cess. Apart from the approach flow sec-tion layout this covers the dimensioningof the vacuum system as well as ofelectrical and mechanical drives. Acomprehensive single-source service isthus available which not only revealsweak points but above all indicatespossibilities for optimizing machine run-nability and improving productivity.

measurements are usually carried out byultrasonic methods.

3. Electric motors and drivesSpeed increases on old machines areoften limited by existing drive and trans-mission concepts. Even if individualdrives are already installed, it may not bepossible to increase motor capacity.Initially this can be checked by measur-ing the motor current consumptions,speeds and temperatures during normaloperation, and comparing them withdesign data. In case where motor speedis the limitation, the problem can usuallybe solved by using different gear ratiosto keep the motor speeds within thedesign range while increasing the speedof the rolls. In cases of doubt VoithSulzer may also consult the drive manu-facturer.

4. Vacuum system analysisIncreasing the machine output generallymeans that vacuum requirements will behigher for the suction rolls and devices inthe wire and press sections. Here again,Voith Sulzer takes comprehensive meas-urements of all vacua and flows involvedin order to analyze the vacuum systemconcept. The most important aspecthere is to check vacuum pump capacitiesversus design characteristics. Thisshows whether the higher capacity canbe met by existing equipment or if newpumps are required. Conclusions are alsodrawn with regard to the design of feltsuction units (number and width of slots)and the interconnection of individualcomponents.

Service

Research and Development46

1

Since the founding of Voith Sulzer PaperTechnology in 1994, group R&D capac-ities have been extended with additionalfacilities at various locations. Accordingto the specialization of VSPT divisions,

the working areasat each researchcentre were like-wise re-defined.Parallel work atdifferent locationshas now beeneliminated, and thecapacities thusfreed are now con-centrated on spe-cific researchactivities. As aresult, customersnow have special-ists at their dispo-sal for solvingproblems in every

area of paper technology, together withthe necessary test facilities and measur-ing systems.

The primary goal of all VSPT R&D cen-tres is to serve our customers. All ournew developments and improvements inpaper technology are directed at higherproduct quality, greater productivity andmore cost-effective paper machinery.

This article presents the VSPT R&D cen-tres and describes their work. In a lateredition of “twogether” we shall be report-ing on research projects of particularinterest (see table for summary of R&Dfacilities).

The author:A. Meinecke,R esearch and DevelopmentHeidenheim

47

HeidenheimAt the Heidenheim research centre, devel-opment work is concentrated on paperproduction, ranging from headbox tosheet processing. This centre is alsoresponsible for research and develop-ment in printing and writing paper pro-duction. Detailed development work iscarried out on special facilities for eachcomponent, such as headboxes, sheetformation and drying systems. The fol-lowing facilities are available for interre-lated process stage testing:

� For sheet formation and press trials, atotal of four test paper machines withvarious sheet formation and press con-cept configurations. These cover aspeed range of 20 to 2000 m/min, withweb widths of 0.5 and 1 m.

� A test coating machine with variouscoating and equalization processes anda Speedsizer. Working width is up to0.85 m and maximum speed is cur-rently 2000 m/min.

� A trial roll cutting machine with vari-able geometrical configuration, foroperation e.g. as two drum or as a onedrum winder.

Numerous development laboratories andmeasuring facilities are likewise avail-able.

Research and Development:The Voith Sulzer Paper TechnologyR & D centres

Voith Sulzer Paper Technology research and development facilities

Working area Location

Stock preparation Ravensburg / GermanyAppleton, Wisconsin/USA

Paper Machines– Writings and printings Heidenheim / Germany– Board and packaging Ravensburg / Germany– Tissue São Paulo / Brazil

Coating Technology Heidenheim/ Germany

Finishing Krefeld / GermanyManchester / Great Britain

Winder Technology Heidenheim / Germany

USA

Brazil

Germany

48

RavensburgResearch work in stock preparation isconcentrated at this centre. Developmentof new and improved processes andmachines – from pulping to bleaching –is carried out on numerous test facilities.The heart of the R&D facilities here is astock preparation line which incorporatesall 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 testedhere under mill conditions. Likewise cus-tomized stock preparation concepts canbe studied and optimized. The extensivelaboratory facilities ensure rapid evalua-tion of stock analyses and other meas-urements in the various process stages.

The Ravensburg test machine is particu-larly suitable for carrying out productiontrials on paperboard and packagingpapers. Over a wide range of basisweights and operating speeds, single andmultilayer or multi-ply papers and boardscan be produced. In the press sectionadjoining the sheet formation section,various press configurations can be builtup using the latest NipcoFlex technology.A great advantage is the close proximityof this machine to the stock preparationline, which allows stock made of specialraw materials to be supplied under millconditions for sheet formation trials.

2

3

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.

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4

5

Research and Development

50

KrefeldHere at the headquarters of the FinishingDivision, R&D work is carried out oncalendering. The main components ofcalenders are tested on special facilities,some of which are equipped withextremely high-resolution measuringsystems. Sophisticated computer simula-tion programs are coming into generaluse for replacing or shortening some ofthe more time-consuming experimentalwork. For various calendering processessuch as soft calendering or supercalen-dering, comprehensive facilities are avail-able which are fitted with the associatedequipment for humidifying, preheating,etc. These allow calendering systems andparameters to be selected and optimizedfor customized requirements. The latestinstallation here is for carrying out testson the Janus concept. Other calenderingtest facilities are available for customertrials at Hunt & Moscrop in Manchester,England.

Appleton, Wis., USAThe waste paper recycling quota is like-wise rising in North America – particular-ly for manufacturing printing and writingpapers. For stock preparation tests, withspecial emphasis on waste paper, a com-plete line with all the various processstages is available in Appleton. Theserange from pulping, screening, cleaningand flotation to disperging, bleaching,thickening and loop water treatment.Tests and optimization trials can thus becarried out under mill conditions on near-ly all stock preparation processes. Stockcan also be prepared from customers'raw materials according to special

6

7

Fig. 6:Krefeld: Finishing Division technology centrewith soft nip calender.

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

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

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

8

9

51Research and Development

52

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

São Paulo, BrazilThis is the latest VSPT research anddevelopment centre, where a trial tissuemachine with a working width of 1 m isinstalled. This machine incorporates thefollowing modules: single or multilayerheadbox, various twin wire configura-tions for sheet formation, a crepe cylin-der with presses and reeler. The machineis completed by a stock preparation lineso 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 willhave significant effects on tissue produc-tion in future.

10

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

53Corporate News

PAPER INDUSTRY PRESS CONFERENCE IN HEIDENHEIM

Workshop, symposium andbirthday party:

At the end of September1995, international journalistsand German business pressleaders met in Heidenheimat the first VSPT paper indus-try press conference. Themotto on this Voith Sulzer

Paper Technology anniversarywas “twogether future forpaper”.

The conference got off to aceremonial start with abaroque trumpet concerto inNeresheim Abbey church –part of the Benedictinemonastery’s ninth centennialcelebrations.

Hans Müller, President andCEO (seen above with KevinChang of Paper Asia) hadevery reason to be content: allthe VIPs of international paperindustry journalism werepresent on this memorableoccasion. The entire VSPTmanagement were gathered at

the Heidenheim engineeringcentre to welcome guestsfrom Australia, Singapore, theUSA and numerous Europeancountries. “For us the press –and above all the paper indus-try press – is a very importantpartner”, said Müller. “As faras technical advances andcustomer benefit are con-

cerned, information is every-thing”.

Does this joint venturebetween former competitorsreally work? Is the new com-pany accepted on the market?What about the present situa-tion and future goals? Thepositive answers to all suchquestions impressed even themost experienced journalists– for the combined forces ofthis joint venture havebrought some notable innova-tions which are making theirmark among customers.

“The Voith Sulzer marriage inpaper technology is workingfine. The future looks promis-

ing. Out of the red straightafter take-off. Unexpectedlyhigh order intake”… Theseare only some of the head-lines appearing after the 1995VSPT press conference. Andeveryone who attended thisfertile round of discussionwants to come back againnext time.

54

BIBLIOPHILI TREASURESNeresheim Abbey, only a few minutes’ drive fromHeidenheim, was founded in 1095 and celebrates its ninthcentennial this year. This monument to European culturalhistory houses a library with some twenty thousandmedieval and early baroque volumes.

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In eastern Baden-Württemberg, at thecrossroads between Heidenheim andNördlingen, Aalen and Dillingen, liesNeresheim – only a few minutes from theWürzburg-Ulm motorway.

Whichever way you approach Neresheim,you will be surprised by an imposing col-lection of buildings dominating the townfrom its 582 m.a.s.l. vantage point – theBenedictine abbey. On a clear day theview from here extends to the Alpinepeaks. This year Neresheim Abbey cele-

Paper and Culture

brates its nine-hundredth anniversary.Founded in 1095 by Graf Hartmann ofDillingen, the abbey has survived all theturmoil of European history.

Already during the first struggle for pow-er between Kaiser and Curia, the abbeywas burnt down by Konrad IV, banishedson of the Hohenstaufen Kaiser FriedrichII, because its monks were loyal to thePope. In 1525 the Peasants’ War ragedover the Härtsfeld, and during theSchmalkaidic War in 1546 Karl V took up

residence in Neresheim Abbey. Towardthe end of the Thirty Years’ War theabbey became headquarters of the Swed-ish General Lorenz von Hofkirch.

The same fate befell the abbey during theCoalition Wars of 1796 to 1801, whenGeneral Moreau set up headquarters forNapoleon’s troops in Neresheim. As if forthe sake of posterity, he nonchalantlyrecorded his daily log in the abbey libraryguest-book.

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The library is not the only attraction,however. Neresheim Abbey is well worthvisiting as one of Europe’s most interest-ing and best-preserved baroque edifices.Construction of the present buildingsstarted in 1694 and took thirty years tocomplete, interrupted by wars and lack offunds.

The crowning glory is the abbey churchdesigned by Germany’s most famousarchitect of the day, Balthasar Neumannof Würzburg who was also an artillerycolonel.

Most important baroque church north of the AlpsWhen Balthasar Neumann, born in 1687of an Eger clothmaker, was approachedby Abbot Aurelius of Neresheim, he wasalready reputed to be the greatest archi-tect between Cologne and Constance. Hiscreative intuition was combined with anenormous capacity for hard work and agenial talent for organization. In his posi-tion as senior architect to the Archbishopof Würzburg, he was responsible for con-struction works throughout the land aswell as for the building materials andglass manufacturing plants which hehimself had founded. As artillery colonelhe was responsible for military defenceand engineering, artillery and fortifica-tions. And as engineer he held an impor-tant teaching post in civil and militaryconstruction. At times Neumann was incharge of more than 10,000 workers dis-tributed among his various building sites.With no telephone communications orcopying facilities and only horse trans-port, this seems an impossible task today– but as we can see, it was indeed pos-sible.

Neresheim represents the peak ofNeumann’s achievements in ecclesiasticalarchitecture. At the height of his creativepowers and in his best years, he incorpo-rated in this building all the ideas inspir-ing his most important work. It is herethat Balthasar Neumann expressed hissense of grandiose celebrity with thegreatest perfection. The masterpiece ofbaroque architecture we are privileged tosee and admire in Neresheim today is atrue statement of timeless nobility.

Two dozen incunabula still remainingDespite all the losses inflicted by war andsecularization, the abbey library stillhouses many other treasures apart fromits notable guest-book. It is one of thevery few baroque libraries in South Ger-many whose form and content hasremained more or less intact over thecenturies. As a highlight among almosttwenty thousand volumes ranging fromthe fifteenth to early nineteenth centuries25 incunabula have been preserved here.The relatively extensive collection as itstands today was built up throughsystematic acquisition and exchange, orthanks to foundations and donations. Anumber of works were acquired as a kindof “morning gift” from the mother houseBeuron and other monasteries when theabbey was newly founded. Prince Albertof Thurn and Taxis and his consort Mar-garetha of Austria bequeathed the newabbey a valuable collection of volumes,which are particularly interesting fromthe art history point of view. At thepresent time the entire collection ishoused in the so-called “new library”,where another 85,000 volumes frommore recent times can be found.

The baroque wing of the monasterybuilding, where the old library is situated,was in danger of collapse but in themeantime has been saved by restructur-ing measures. Interior restoration work isstill underway, with particular outlayrequired for the library room with its val-uable stucco ceilings. Thanks to gener-ous support from local firms, the Baden-Württemberg authorities and internation-al well-wishers, it is hoped to reopen thelibrary in one or two years as a Europeancentre of learning.

Paper and Culture 57