1

Dear Customers, Dear Readers,Hans Müller,
President and CEO,Voith Sulzer Papiertechnik GmbH

“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 reputed
customer in the USA reflects the overwhelming response to
our first edition of “twogether” magazine. Not only the paperindustry, but also professional associations, academic institutes
and the trade journals were unanimous in this acclaim. Bearing
in mind today’s flood of printed media and pressure of time, 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 strategy
of closer customer contact. What are the next steps? How will
the situation of papermakers and machinery manufacturers
develop in the context of increasingly rapid global market
changes? A dependable way of foretelling the future would
certainly be the dream of all investors.
Some weeks ago we received an interesting paper on this theme
by Riccardo E. Moeschlin, an expert not unknown in the paperindustry. How valid are such forecasts? Since no recipe exists
for reliable prognoses, and as human beings we are all prone toerror, this theory based on repetitive economic cycles seems
particularly interesting. Read on and judge for yourself!
One again, we trust that “twogether” No. 2 brings you interestingreading and some useful technical information.
Sincerely

Hans Müller

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Aus dem Unternehmen

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Aus dem Unternehmen

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

STARTUPS
Stock preparation
Waste paper processing systems
and subsystems for printings andwritings
945,000 tonnes p.a.
ANM Albury, Australia
Stora Feldmühle, Langerbrugge,
Belgium
Utzenstorf Paper Mills,
Switzerland
Hann. Paper Mills, Alfeld, Germany
Stora Feldmühle, Kabel, Germany
MD Paper, Germany
SCA Aylesford, Great Britain
Georgia Pacific, Kalamazoo, USA
Waste paper processing systems
and subsystems for board andpackaging papers
550,000 tonnes p.a.
Visy Paper, Australia
Lenk Paper Mills, Kappelrodeck,
Germany
Townsend & Hook Ltd, Snodland,
Great Britain
P.T. Indah Kiat, Indonesia
Board AB, Fiskeby, Sweden
Hansol Paper, South Korea
Shin Poong, South Korea
Visy Paper, Conyers, USA
Waste paper processing systems
and subsystems for tissue papers
148,000 tonnes p.a.
Thrace, Greece
Apizaco, Mexico

AS Sunland Eker Paper Mills,
SwedenPope and Talbot, Wisconsin, USA
Scott, Owensboro, USA
Waste paper processing systems
and subsystems for other types of
paper
110,000 tonnes p.a.
Kemsley, UK Paper, Great Britain
Auburn VPS, USA
Chemical pulp processing systems
MD Paper, Dachau, Germany
Stora Billerud, Baienfurt,
Germany
Weißenborn Paper Mills,
Germany

Paper machines
264,000 tonnes p.a.
Printings and writings
Tamil Nadu Newsprint and Papers
Ltd, Madras, India
Board and packaging papers
Visy Paper, Australia
Willamette Ind. Inc., USA
Hansol Paper Co. Ltd, Korea
Rebuilds
Visy Paper Conyers, USA
Haindl Paper GmbH, Walsum,
Germany
Cartiere Burgo SpA, Italy
Stora Billerud GmbH, Germany

Holmen Paper AB, Sweden
Haindl Paper GmbH, Schongau,
Germany
MD Paper GmbH, Germany
PWA Graphical Papers GmbH,Germany
Albbruck Paper Mills,
Germany
Kanzan Spezialpapiere AG,
Germany
Smurfit Newsprint Co., USA
Stora Grycksbo AB, Sweden
Stora Langerbrugge N.V., Belgium
Steinbeis Temming, Germany
Norske Hönefoss, Norway
Stora Feldmühle, Hillegossen,
Germany
Stora Forest Industries, Canada
Coating technology
Votorantim Celulose e Papel Simao
Jacarei, Brazil
Kanzan Spezialpapiere GmbH,Germany
International Paper, Poland
Consolidated Papers Inc., Biron Mill,USAMD Paper, Germany
Albbruck Paper Mills,
Germany
Zaklady Celulozowa Papiernicze
S.A., Poland
Saica Zaragoza, Spain
Ripasa S.A. Celulose e Papel,
Limeira, S.P., Brazil
Kostryznsie Zaklady Papierniecze
S.A., Poland
Scheufelen Paper Mills,
Germany

Winding technology- Duoreel
Haindl Paper GmbH, Walsum,
Germany- WindersTamil Nadu Newsprint and Papers
Ltd., Madras, India
Haindl Paper GmbH, Schongau,
Germany
Smurfit Newsprint Corp., USA
Visy Paper, Australia
Visy Paper Conyers, USA
Kostryznsie Zaklady Papierniecze
S.A., Poland

Finishing
Supercalenders
Burgo Ardennes, Belgium
PTS, Germany
Jiangnan Paper Mill, China
Soft calenders
Henry Cooke Makin, Great Britain
Pap. de Gascogne, France
NN, Germany
Jang Chun, Korea
Georgia Pacific, USA
Portals, Great Britain
Shandong, China
Hannover Paper, Germany
Pap. Calparsoro, Spain
Longview Fibre, USA
Inland Empire Spokane, USA
Visy Board, Australia
Tai Shan, China
Zhu Hai, China
Sappi Specialities, Great Britain

7
Papelera De Castilla Duenas, Spain
Sam Poong, Korea
Suzano, Brazil
Perlen paper Mills, Switzerland
SNIA f. Krasnokamsk, Russia
Long You Paper, China

Machine calenders
Crown Packaging, Canada
Australian Paper Botany Mill,
Australia
Zhu Hai, China
Crane Byron Mill, USA

Weyerhaeuser, USA
Rebuilds
Arjo Wiggins, France
Koehler, Germany
Pudumjee, India

Roll transport systems
Bruckmann, Germany
Maul Belser, Germany
Burgo Ardennes, Belgium
KNP Leykam, Netherlands

ORDERS ON HAND
Stock preparation
Waste paper processing systems
and subsystems for printings andwritings
1,466,000 tonnes p.a.
Hermes Paper Mills, Germany
Parenco B.V, Netherlands
Trust International Paper Corp.,
Philippines
Holmen Paper Mill, Braviken,
SwedenAustralian Newsprint Mills,
Australia
Jiangmen, China
Stora Kabel GmbH, Germany
Paper Industries Corp., Philippines
Halla Engineering & Heavy
Industries Ltd, South Korea
Hansol Paper Co. Ltd, South Korea
Georgia Pacific, USA
Dae Han Paper, South Korea
Genting Newsprint Sdn. Bhd.,
Malaysia
Waste paper processing systems
and subsystems for board andpackaging papers
2,479,000 tonnes p.a.
Ningbo Zhonghua Paper, China
CMPC Procart, Chile
Zülpich Paper GmbH & Co. KG,
Germany
SCA De Hoop, Netherlands
VSDN Cape Kraft, South Africa
Cheng Loong Co. Ltd., Taiwan
Thai Kraft Paper Industries Co. Ltd.,
ThailandGeorgia Pacific, USA
Port Townsend, USA
PT Indah Kiat, Indonesia
Waste paper processing systems
and subsystems for tissue papers
93,000 tonnes p.a.
A/S Sunland Eker/Papirfabrikken,
NorwayCrisoba Industrial, Mexico
Waste paper processing systems
and subsystems for other types of
paper
478,000 tonnes p.a.
Australian Paper Manufacturers,
Fairfield Mill, Australia

St. Petersburg Carton Combine, CIS
Corenso United Ltd, Finland
Chemical pulp processing systems
597,000 tonnes p.a.
Neidenfels/Blue Star,
Germany/China
Tronchetti, Italy
Hiang Seng, Thailand
Pulper feed systems
Stora Feldmühle, Belgium
VPK Oudegem, Belgium
Ningbo Zhonghua Paper, China
St. Petersburg Carton Combine,
CIS
Corenso United Ltd, Finland

Paper machines

Tien Long Paper Mill, Taiwan
Industria Cartaria Tronchetti Burgoa Mozzano, Italy
Rebuilds
Visy Paper, Australia
Bataan Pulp and Paper Mills Inc.,
Philippines
CMPC, Santiago, Chile
Thomas Tait & Sons Ltd,Great Britain
Tentok paper Co. Ltd, JapanDavidson & Sons, Great Britain
United Paper Mills Ltd, Finland
Federal Paperboard Co., USA
Consolidated Paper Inc., USA
Rigesa Celulose, Papel e
Embalagens Ltda, Brazil
Assidoman Kraftliner, Sweden
Westvaco Corporation, USA
Stone Container Corporation, USA

3,198,000 tonnes p.a.
Printings and writings
Consolidated Papers, Stevens Point,
USA
Holmen Paper Mill, Braviken,
SwedenSCA Ortviken AB, Sweden
Sinar Mas Pulp & Paper Ltd, India
Halla Paper Co. Ltd, Korea
Mazandaran Wood and Paper
Industries, Iran
Board and packaging papers
Visy Paper, USA
Zülpich Paper GmbH & Co. KG,
Germany
Victorgo Industries Guangzhou,
China
VPK Oudegem, Belgium
Ningbo Zhonghua Paper Co. Ltd,
China
Thai Kraft Paper Industry Co. Ltd,
Thailand
Visy Paper, Brisbane, Australia
Mazandaran Wood and Paper
Industries, Iran
P.T. Indah Kiat, Pulp & Paper Corp.,
Indonesia
CMPC-Cia. Manufacturera de
Papeles y Cartones S.A., Chile
TissueBacraft, Brazil
Al Keena Hygienic Papermill Co. Ltd,
JordanCoating technology
Nippon Paper, Japan
Koehler Paper Mills GmbH,Germany
Federal Paperboard Comp. Inc.,USASCA Ortviken AB, Sweden
Hansol Paper Co. Ltd, Korea
Halla Paper Co. Ltd, Korea
Hong Won Paper, Korea
Consolidated Paper Inc. Stevens
Point, USA
Kymi Paper Mill, Finland
Winding technology- DuoreelSCA Ortviken AB, Sweden
Koehler Paper Mills GmbH,Germany
Holmen Paper AB, Sweden
Industria de Papel Arapoti SA,
Brazil- Winders
Halla Engineering & Heavy
Industries Ltd, Korea
Papeles Bio Bio SA, Chile
Holmen Paper AB, Sweden
Genting Newsprint Sdn. Bhd.,
Malaysia
Fabricadora de Papel de Celulose
S.A., Brazil
Townsend & Hook Ltd,Great Britain
Guangzhou Victorgo Industries Co.
Ltd, China

Companhia Suzano de Papel e
Celulose, Brazil
International Tendering Company
CNTIC, China

Finishing
Supercalenders
KNP Leykam, Netherlands
Yuen Foong Yu, Taiwan
Bosso, Italy
UPM Tervasaari, Finland
Marubeni for Daishowa, Japan
Hansol Paper, Korea
Soft calenders
Genting Newsprint, Malaysia
CMPC Procart, Chile
Ballarshah, India
Siam Paper, Thailand
Pap. del Aralar, Spain
Miliani f., Hungary
Assi Domän, Sweden
Kymmene Wisaforest, Finland
Simao, Brazil
Henry Cooke Makin,Great Britain
IP Kwidzyn, Poland
J.R. Crompton, Great Britain
Portals, Great Britain
Ningbo PM 3, China
Ningbo PM 2, China
Halla Paper, Korea
Holmen Paper, Braviken Mill,
SwedenSCA Ortviken, Sweden
Machine calenders
Australian Paper, Australia
Ningbo, China
Townsend & Hook Ltd,Great Britain
Crown Packaging, Canada
SCA Ortviken, Sweden
Rebuilds
Stora Kabel, Germany
Stora Reisholz, Germany
Cart. Toscolano, Italy
Roll transport systems
KNP Leykam, Netherlands
Scheufelen Paper Mills, Germany
NDI, Netherlands
Halla Paper, Korea
Genting Newsprint, Malaysia

8

NEW PLANTS AND SYSTEMS
Stock Preparation Division:
The first waste paper recycling line
at MD Papier GmbH, PlattlingThis recycling line with its trend-setting
technology recently went into service
after more than two years of fruitful collaboration with MD Papier GmbH. To
meet specific requirements, conventional recycling technologies were further
developed and adapted accordingly.
Capacity of the new Plattling recycling
line is 72,000 t.p.a. of waste paper
furnish. Design services and machinery
were supplied by a consortium mainlycomprising Voith Sulzer Stock Preparation GmbH, Ravensburg, B+G Fördertechnik GmbH, Euskirchen, and Maschinenfabrik Andritz, Graz/Austria.
MD Papier GmbHhas invested 53
million DM here ina recycling linewith almost entirely closed-circuit water loop
layout. This represents a significant
contribution
toward increasing
the waste paper
recycling quota in
Germany, a selfimposed obligationof paper producers

and publishers which was agreed inautumn 1994. Primary design criteria forthis recycling line were environmental
compatibility and consistently high product quality. Thanks to completely newtechnological developments, it is now
possible for the first time to use oldlabels from reutilized beer and beveragebottles as furnish for making high grade
printing papers. This is done by efficient
removal of inks, stickies and wetstrength additives.
Previously, old labels of this kind were
disposed of in landfills or used as filler
material in the tile and brick industry,
thus wasting the high-grade kraft pulp of
which they were made.

waste paper) as well as higher-grade
standard furnish such as printing waste,
returns and department store catalogues.
Depending on processing mode (special
or standard grade waste paper), the correct machine sequence can be run
accordingly. The goal of this line concept
was dual utilization of as many aggreStock processing line flow diagram
for standard waste paper
Raw materials treatment
Pulping
HC cleaning
Hole screening

The so-called eco-agreement signed by
MD Papier together with several breweries creates the logistical conditions
required for label recycling. As a result,some 60,000 tonnes of bottle labels circulating every year in Germany can now
be used as furnish for high grade products.
The new recycling line – the first of its
kind – makes this technically feasible byallowing the use of high wet-strength
labels and punchings (special-grade 1

Flotation
LC cleaning
Slot screening
Thickening
Disperging
Bleaching
Wet lap unit

StorageStock Preparation

9, PRODUCT DEVELOPMENTS
Fig. 1:
Stock processing line flow diagram for standard
waste 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 Paper
Technology Group.

2

gates as possible in both modes. Daily
capacity is up to 220 tonnes of waste
paper.

conveyor automatically as soon as a predetermined waste paper charge has been
fed to the pulper.

Raw materials handling
Waste 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 by
the same company.

Pulping and HC cleaning
The waste paper is pulped at a stock consistency of 15-17% in an intermittent
high-consistency pulper. This is designed
for maximum fibre retention and efficient
deinking.

The integral weighing system stops the

All deinking additives are fed to the pulper together with each charge.

The pulper is drained via a PreClean
system, which minimizes dumping time
while at the same time ensuring consistent mixing of dilution water during
dumping. It also ensures efficient junk
removal.
The 2-stage PreClean system comprises a
Fiberizer with special rotor/screen combination, 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 rejects
are recovered in the drum screen before

10Fig. 3:
Hole screening in the Fibersorter.
Fig. 4:Compact flotation cell.

they are dewatered and compacted in therejects screw press.
The pulp is pumped into one of three
200 m 3 dumping towers in order to ensure
adequate fibre swelling and chemical
reaction of the deinking additives. Pulp
leaving the dumping tower then passes
through a high-consistency cleaner.

Hole-screening
Basic principle of the 3-stage holescreening system is early removal ofscreenable rejects, with systematic forward feed of accepts.
The first and second screening stages
comprise two Omnisorters for standard
waste paper, or two Fibersorters for special-grade WP. Coarse rejects are 3
removed in the third stage, which comprises a Rejectsorter.

Flotation
In the flotation stage all the ink particles
and finely disperged impurities are
removed. This gives a consistently highquality recycled product which meets all
requirements for manufacturing printing
papers.
The flotation aggregate comprises five
primary deinking cells and one secondarycell. These closed-circuit cells arearranged in pairs, one above the other.
Flotation air is injected into the stock
suspension through independently operating step diffusors. Thanks to the highair content (up to 60%) and wide bubble
spectrum, all ink particles from 10 to 500µm in size are removed. The closed-loop 4

Stock Preparation

11

Fig. 5:
Stock thickening in the double wire press.
Fig. 6:
Disperger with heating screw.

flotation air circuit prevents polution of
the atmosphere.
In the secondary cell any fibres still
usable are recovered. The sludge remaining is dewatered as far as possible in theprescreener before treatment in thesludge handling unit (supplied by
Maschinenfabrik Andritz).

Low consistency cleaningand slotted screening
The small heavies, sand and plastic particles are removed in a 4-stage heavies
cleaner.
Rejects are treated with the sludge, while
the accepts are processed for lightweight contrary removal.
5

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

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

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Fig. 7:
Washing in the VarioSplit.
Fig. 8:View of storage tower.

7

8

Washing and wet lap system
For processing special-grade waste paper
furnish, the stock is washed in a Vario
Split after low consistency slotted
screening. It is then processed in a wet
lap unit and paletted ready for dispatch.

Storage
After medium consistency bleach disperging, standard waste paper stock is
pumped to a storage tower.

Water loops
The water loops in this stock preparationline are almost entirely closed-circuit.
Except for added dilution water andsealing water, no fresh water is used. The
sludge dewatering filtrates are purified
by microflotation in a Purgomat, andreturned to the stock preparation processwater loop. The VarioSplit filtrate is likewise cleaned by microflotation.

Rejects compacting
Coarse rejects from the PreClean dumping system and hole screening are dewatered and compacted in a rejects screwpress.
Rejects from the high and low consistency cleaners are transported by container
for landfill disposal together with compacted rejects from the screw press.

Stock Preparation

13

Fig. 9:Water purification by Purgomat.

914

Stock Preparation Division:
The C-bar screen basket – a high-tech productAccording to an old saying: “paper ismade in the Holländer”. Despite the common 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” feeding
the paper machine– is to process
basic papermaking
materials according to the required
product grade andquality. Screening
has always been
an important partof stock preparation, and since therise of waste paper
as a basic material, it has become
The author:
even more imporR. Rienecker,
Product Grouptant.

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

Screening machines today generally
operate under pressure, and the pulp has
to 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 holes
or slots depends on the kind of rejects
to be removed. The rule of thumb here
is to use holes for flat materials (suchas foils) and a slotted screen for cubic
particles (e.g. styropor). The idea is thatthe stock fibres should pass throughthe screen and the unwanted materials
should remain for subsequent removal.

ScreeningWith traditional primary furnish such as
groundwood and chemical pulp, the components to be screened largely comprisesolid particles such as splinters. With
greater use of recycled paper, the main
requirement now is to remove softercomponents such as stickies, foils, styropor and other rejects. This is much
more difficult than screening out solid
particles.

The main importance of screening technology lies not so much in the finishedpaper quality, but in the cost-effectiveness of the paper production and finish-

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 stock
despite more use of dirty waste paper,very small screen holes or slots have to
be used – and the trend is more andmore toward fine slots.

Slotted screens are nothing new, but eversince the screen was invented they
have played a secondary role. Slotted
screens in the past comprised flat plates
in which slots were cut painstakingly≥(Fig. 2). These were generally 0.8 mm
wide, but for special applications slots as
small as 0.45 mm were used.

The limits of slotted screens were dictated by manufacturing processes, whichallowed a relatively small amount of free
screening area, and by the low rotor efficiency due to the smooth surface. Boththese factors reduced throughput, so thatslotted screens were relatively uneconomical.

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 manufacturing methods at that time did notallow either for modifying screen flow
conditions or for increasing the free
screening area. The only possibility
remaining was to increase turbulence,and hence throughput, by adding bars to
the rotor side of the screener basket.

As a further development of these highturbulence screener baskets, a wide
variety of surface profiles were proposed.
One example is the so-called VV basket(Fig. 4), comprising a large number of“minibars” generated by milled grooves
in the basket surface. The principle here
was that the depth of these grooves influences screening efficiency to a certain
extent. In simple terms, a very rough surface increases throughput, while asmoother surface increases screening
efficiency.
All these screener basket versions had

Stock Preparation

15

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

inlet

1

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

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

5
2
3
4

accepts
rejects

1

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

The slot width is defined by the bar spacing, 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 baskets
are far superior to their machined predecessors. This superiority can be summarized as follows:

smoothbar type

VV type

I Higher screening efficiency for thesame slot width
I No sharp edges
I Large free screening area

2

3

4

I Lower screening energy consumption

16

Fig. 5:
Principle of the conventional bar-type basket.
Fig. 6:
Principle of the C-bar screen basket.

Direction of rotor rotation

Directionof rotor
rotation

View AA

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 loads
for long periods in the screening machine, and is often exposed to abrasive
attack 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.

5

Direction of rotor rotation

Directionof rotor
rotation

View AA

On top of this, the use of chrome-nickel
stainless steel turns the development ofsuch a screener basket into an engineering challenge of the first magnitude.

The manufacturing process involves thefollowing main steps:

I Precise cutting of the clamping profile

6in the bars by laser technique
I Low-cost manufacturing

These fabricated screen baskets also havetheir manufacturing limits, however:

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

0.2 mm since narrower slots require
thinner bars and reduce basket
stability.

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

eliminated by developing and patenting
an innovative manufacturing process.

I Production of a flat screen by fitting

All problems were solved through close
cooperation between manufacturing specialists and stock preparation experts,
and the result is a mature screen basket
meeting all market requirements.

specially drawn profiled bars on a
newly developed welding machine
I Rolling the flat screen into a cylinder
and welding the ring ends together
I Machining the end flange and welding
it to the cylindrical screen
I Finish-machining the entire screenbasket.

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

Each of these manufacturing steps – particularly welding and rolling – not only
demands precise work planning but high-Stock Preparation

17

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

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

≤≤

The problem of weld faults at the connections between profile bars and stiffening
rings does not apply to the C-bar manufacturing process, because the bars areclamped into the rings and not welded.

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

I Bar-type basket without welding points

in the screen structure
I Rings and bars shaped to clamp

8

together80%

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

70%
C - bar-basket

60%
50%
40%

Conv. bar-type
30%
20%
10%

the longitudinal direction due to closely spaced stiffening rings
I High surface quality (cold-drawn bars
without welding)
I 0.1 mm slot width easily reproducible
I Large free screening area
I Optimally variable profiling (no manufacturing limits).

07≥ 0,15

0,2

0,25

0,3

≥0,35 mm

Customer appreciation of these advantag-

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

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

18

Stock Preparation

Fig. 9:Macro-view of the C-bar screen basket.
Fig. 10:
Nothing succeeds like success: more than
700 C-bar baskets in various sizes have gone
into service in a short space of time.

An important point is that in many cases
existing screens cannot simply be
upgraded with C-bar baskets. The operating parameters have to be taken into consideration as well as the kind of screen
and the system layout, etc. Above allwhen extremely fine slots are required,screen and system behaviour deviatesfrom experience with previous basket
types.

9

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

10

C-bar baskets are currently in service for
LC screening on waste paper stock preparation lines, for screening woody pulp
and in approach-flow screening systems.
They are soon to be used for medium
consistency screening, and trials are
already underway.

New applications and the associatedproblems demand continuous development work on the C-bar basket, bothfrom the design point of view and withregard to manufacturing. By entering thishigh-tech field at an early date, Voith
Sulzer has acquired not only considerable
know-how in manufacturing C-bar baskets, but also wide background knowledge on their applications in the paperindustry. This allows fast reaction to new
demands.

19

Stock Preparation Division:
The EcoCell, an example of synergy
effects in flotation cell development
The new EcoCell combines the advantages of both existing Voith-Sulzer flotation
cells – the E-cell and the Compact Flotation cell. These comprise on one hand thedesign features of the E-cell (simple
control strategy, practically unlimited
scale-up and inside aeration element),
and on the other the technological benefits of the CF-cell (excellent efficiency in
reducing a wide ink particle size range).
This has beenachieved by applying the CF-cell
aeration principle
to the E-cell aeration element. Initialtests on a pilot
plant have confirmed the outstanding efficiency of the
new Voith Sulzer
EcoCell, and thesewill now be followed by operational trials in apaper mill.

The authors:
T. Martinand H. Britz,
product group
Flotation

After Sulzer Papertec
and
Voith
joined forces inpaper technology,
one question was,which type of flotation cell should
be followed up asa joint Voith-Sulzer product – theE-cell or the Compact Flotation cell(see Figs. 1 and 2).

Close comparison of the two types withregard to technology, design and operating principle brought the following findings:
The design advantages of the E-cell lie inthe cell unit and periphery (Fig. 1):

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

I Uncomplicatedscale-up on a linearbasis
I No scale-up limitations (except possible pumping limits)
I Simple level control by compensation
between cells, i.e. only one level control loop per stage
I Interior aeration element, particularly
advantageous with closed-circuit process air loops.

The next step was obviously to try andcombine the advantages of both types. A
valuable basis for this was the thoroughresearch work carried out by Sulzer
Papertec on further development of thecompact flotation cell. It was found that
greater efficiency particularly in dirt
speck removal could be reached mainly
by modifying the hydraulics of the air
injection element.

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

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

Comparative testing on the Ravensburg
pilot plant showed that for relatively easily deinked waste papers (newspapers/
magazines), both types of cell give equally good technological results in theirstandard layouts.

For waste papers which are difficult todeink, such as mixed office waste, laserprint and multiprint, the CF-cell removes
large ink particles (200-400 µm) considerably better than the E-cell (see Fig. 4).
Based on these findings, it was decided
to use the E-cell for easily deinked waste

As shown in Fig. 5, the comparative tests
carried out on the new aeration element
prove the technological superiority of the
EcoCell both for easily deinked waste
papers (newspapers/magazines) and difficult grades such as laser and multiprint.

As a next step, these positive results will
be confirmed by practical trials on a flotation unit.

20

Stock Preparation

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

Fig. 1:
Principle design of the Voith Sulzer E-cell.
Fig. 2:
Principle design of the Voith Sulzer
Compact Flotation cell (CF).

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

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

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

Inlet
Process Air

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

Foam
AcceptInlet
Air

3-stage air
aeration
element

66

Max. flotability limit

64
62
60
58
56
50% newspapers
50% magazines
Stock consistency 1.1%

54
52
50
0

Accept

1

2

3

Foam

100
80
60
40
50% laserprint,
50% multiprint
Stock consistency 1.1%, 4 cells

20
0

4
5
6
Number of cells

CFC cell0

E cell

100

200

300
400
Particle size [µm]Both cells withstandard aeration elements

Stock
Process air

62

Max. flotability limit

60
58
56
54

Step diffusor

50% newspapers
50% magazines
consistency 1,1%

52
50
0

Impack mixer
Distribution
diffusor

1

2

3

4
5
6
Number of cells

E cellmixing-bundle injector

5

Reduction in Dirt speck area [%]Brightness [% ISO]

4

2

3

Reduction in Dirt speck area [%]Brightness [% ISO]

1

100
80
60
40
50% laserprint
50% multiprint
Stock consistency 1.1%, 4 cells

20
0
0

100

EcoCell
new aeration element

200

300
400
Particle size [µm]

21Paper Machines Division:
NipcoFlex shoe press –the new product symbiosis
lubricating oil distribution pipe spreads
cool oil uniformly over the sleeve immediately after the press nip, thus ensuring
freedom from wear. An added benefit ofthis single-source system is the aboveaverage life of the yarn reinforced QualiFlex press sleeves, a patented product ofVoith Sulzer Paper Technology.

80
70
60
50
Number of installations

In 1984 the world's first closed shoepress went into service: the Voith Flexonip press. Two years later followed theSulzer Escher Wyss equivalent: the Intensa-S shoe press. Thanks to their highefficiency and outstanding technologicalresults, both systems soon became wellestablished (see Fig. 1). A total of
26 Flexonip and 28 Intensa presses
are now in operation, mainly for brown
paper and paperboard production.
Since Voith Sulzer
Paper Technology 1
wasfounded,orders have been
booked for another
15 Flexonip andIntensashoepresses.

40
30
20
10
0
1985 1988 1991 1994 1997

Flexonip Presse

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

Nipco-Intensa-S-Presse

The joint venture
between Voith andSulzer in paper
The author:
W. Schuwerk,
technology
hasNipcoFlex Technology
brought a symbiosis of the bestproducts from both sides. Based on more
2than 200 years of accumulated operating
experience with closed shoe presses, thepress with the pressing system of thegreater patent freedom now applying has
Intensa press. Pressed against the roll bybeen exploited to unite the advantages ofindividual elements, the shoe is made up
both concepts in a single product: theof an top and a bottom part which are
NipcoFlex press. This symbiosis is notthermally insulated from each other. As alimited to the roll and shoe alone, but
result, thermal deformations are largely
also includes the backup roll – in otheravoided. The shoe is asymmetrical to thewords, the entire press system (seepressing direction, displaced toward theFig. 2). Since the market launching ofingoing nip. The flexible roll sleeve isthis concept, ten NipcoFlex presses have
likewise asymmetrical to the pressing
already been sold.
direction, thus allowing a more favourable sleeve intake geometry. Lubrication
The new NipcoFlex roll shown in Fig. 3
between the press shoe and roll sleeve is
combines the shoe design of the Flexonip
purely hydrodynamic. To this purpose a

NipcoFlex-Pressepressure rises more gradually to ensure
uniform compacting. In zone 3 the pressure falls off steeply to prevent rewetting.
This kind of pressure characteristic is
indispensable for gentle dewatering and a
uniform sheet structure with greatest
possible volume retention. Apart from
this, pressure profiles with moderate gradients and low maxima also give longer
felt and sleeve life.
As backup to the NipcoFlex roll, theNipco-P roll shown schematically in
Fig. 5 combines the advantages of the

22Fig. 3:
Cross-section through an inverted NipcoFlex roll:
1. Support structure, 2. Sleeve guides,
3. Press roll sleeve, 4. Lubricating and cooling oil,5. Oil return, 6. Hydrostatic oil, 7. Lubricating oil
distributor, 8. Pressing element, 9. Press shoe.
Fig. 4:
Ideal pressure profile.
Fig. 1: (page 21)
Sales development of Voith and Sulzer
shoe presses.

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.

classical Nipco roll with the stable bearing positioning of the profile roll. In fact
the designation Nipco-P stands for “position-stable”. The roll bearings are spaced
directly opposite the main roll bearings,
and therefore unaffected by the inevitablebeam deflection. This brings some
important advantages with regard topress operation. According to the wellproven Nipco principle, the roll shell
run on internal hydrostatic support
elements. As shown in Fig. 6, these
operate on identical bearing surface areas
in both rolls and are supplied with 4hydrostatic oil from a common feed pipe.
This allows extremely simple and reliable
control, only one valve being required,and neither the roll bearings nor roll shell
can be damaged under any circumstances. Only at the edges are small
compensation elements required forpressure relief in case the web width ischanged.
One of the main reasons for the versatility of the NipcoFlex press is its compact
bearing frames (see Fig. 7). Thanks topatented link elements, mechanical forc-

1
2
3
4
5
6
7
8
9

3

II

I

is enormous potential for improving
dry content, output and product quality.
By using a shoe press instead of aconventional third press, dry content wasincreased by 5% to 49-50% – despite a
200 m/min speed rise to nearly 1200
m/min – thanks to the sixfold increase inline force (see Fig. 8). This brought a
productivity rise of more than 16% without any reduction in specific volume,
which was even increased slightly. Sheetsmoothness and 2-sided uniformity after
soft calendering were improved at thesame time. The technological results andIIIpressure

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

Time
Zone l: Relatively steep pressure rise
until dewatering
Zone ll: Flatter pressure rise during
dewatering
Zone lll: Steep pressure fall to prevent
rewetting

1

2

3

4

5

6

7

5

es are transmitted directly from roll toroll without the need for massive supports. This allows simple press design
with good accessibility, as well as fast
felt and sleeve changing.
So far shoe presses have mainly beenused on paperboard and packaging paper
machines, and only now are they coming
into use for manufacturing wood containing and wood-free printing papers.
Operating experience with the world’s
first shoe press on a newsprint machine
has shown that in this field as well, there

cost-effectiveness of this concept havecomplied with all expectations.
For extremely high operating speeds,
shoe press concepts with closed-loop
web runs are available. In mid-1996 theworld’s first 4-roll press with integral
shoe press in the third nip is due to goon line in a 9.6 m wide newsprint
machine operating at 1800 m/min. Compared with existing concepts, the designof this Duo-Zentri NipcoFlex press (seeFig. 9) represents a real quantum jump.
With dry content reaching 48% or more

Paper Machines

23

Fig. 6:
Pressurizing system of a
NipcoFlex press.
Fig. 7:
Mechanical force transmission:
Conventional shoe press (left)
Compact NipcoFlex press (right).

Nipco-P rollP

I

Pressure inhydrostatic
elements

End zone reliefA

NipcoFlex roll

P

X

B
T

System P
I
pressureM
6

7

immediately after the press at an operating speed of 1700 m/min, and a basis
weight of 42 g/m 2, productivity expectations on this machine are high indeed.
Another decisive advantage over conventional 4-roll presses is of course the highvolume retention during dewatering in
the last nip.
Before shoe presses come into generaluse for wood-free writing and printing
papers, a good deal of testing and operating experience is still required. The
trend is clear, however: not only do shoepresses bring the decisive advantages ofhigher dry content and greater productivity, but in particular they also improve
product quality. For these reasons shoepresses will soon be state-of-the-art for
printing and writing papers as well asboard and packaging products.

24Paper Machines

Fig. 8:
Technological results after conversion to
NipcoFlex (Perlen No. 5 newsprint machine).
Fig. 9:
Example of a Duo-Zentri NipcoFlex press.

Before rebuild
960 m/min

After rebuild
1060 m/min

Dry content

Newsprint 43 g/m2
55

49%

Dry content [%]

50
45

44%

40
35

Before rebuild

Specific volume

1.68

1.0

After rebuild

3.5

3.3

3.4

After
calendering
3.1 3.1

3.0

TS RS

TS RS

Before rebuild

After rebuild

Oil adsorption (COPB) [g/m2]

1.67

PPS roughness [µm]Specific volume [cm3/g]
9Newsprint 43 g/m2

4.0

Before rebuild

8

Newsprint 40 g/m2

3.0

2.0

Oil adsorption (COPB)

PPS roughness

Newsprint 40 g/m2

After rebuild

30

20

18.3

17.2

15.6

15.7

TS RS

TS RS

Before rebuild

After rebuild

10

25

Paper Machines Division:
Top DuoRun – a new dryer concept
for high-speed paper machines
Summary
Machine operating speeds at the present
time for producing printing paper are justover 1500 m/min on average, and newmachines are now being designed forspeeds up to 1800 m/min. Main requirements on the drying section of these fastrunning paper machines are high availability and high specific evaporation
capacity, with minimum energy outlay for the productgrade in question.
The Top DuoRunwith its overhead
dryer aggregatesand DuoStabilizers
meets all theserequirements. The
web is supported
throughout
theentire drying proThe author:
cess, and in case
M. Oechsle,of a break waste
Drying Technology
material falls on aconveyor belt whichfeeds it to the pulper. Thanks to shortdryer groups at the beginning and endof the drying section, longitudinal web
stretch and lateral shrinkage are compensated so that folds and breaks are eliminated. The combination of DuoStabilizers
and drilled guide-rolls fixes the web on
the dryer fabric, which not only stabilizes
operation in the dryer section but also
makes for lower operating costs. The
ropeless tail transfer system ensuressafe and reliable transfer through thedryer section, and an intermediate floor
underneath allows better space utilization. The DuoCleaner keeps the dryer
fabric clean at all times, thus ensuring
good evaporation and reducing dirt con-tent in the paper. In the V-Top DuoRun,
the dryer section is arranged as a single
line in vee-form, thus shortening it by
about 20%.

Introduction
During the course of dryer section development, the bottom cylinder of a slalom
drying group was replaced by grooved
guide rolls for the dryer fabric. This was
the beginning of single-tier paper drying.
In front of the run-in gusset between thegrooved roll and dryer fabric, a stabilizer
had to be installed to prevent web lift due
to air inclusions. This led to problems in
the edge zones of the web, where air
inflow prevented fixing to the dryer
fabric.

For high operating speeds, the grooved
rolls were replaced with suction guiderolls. These fix the web over its entire
width to the dryer fabric and counteract
centrifugal force. The pre-suction zone of
the roll, where the entrained air is sucked
away, replaces the web stabilizer.

Combi DuoRun
The Voith Sulzer Combi DuoRun is acombination of single-tier dryer group in
the first part, and double-tier dryer groupin the second part of the dryer section. In
modern paper machines this concept
operates successfully at speeds up to1500 m/min. With rising speeds, the number of double-tier drying groups and thenumber of cylinders per group has been
reduced since problems were caused by

the damp web in the open draw of the
double-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 doubletier group with six cylinders. This was
the first paper machine in the world tohave only one double-tier drying group.
The start up was in 1993 and now
operates at more than 1500 m/min.

Top DuoRun
The latest generation of printing paper
machinery is designed for operating
speeds up to 1800 m/min. These highspeeds and much higher investment
costs place more stringent requirementson the drying section:

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

In order to meet all these requirements atsuch high operating speeds, Voith Sulzer
developed the Top DuoRun dryer section
concept described in the following.

The Top DuoRun (see Fig. 2) comprises asingle-tier dryer group with overhead
drying cylinders. Under the cylinders are
drilled guide-rolls, together with DuoStabilizers. Compact short dryer groups
are installed at the beginning and end of
the drying section.

26

Fig. 1:
Combi DuoRun.
Fig. 2:
Top DuoRun.

12

Due to the overhead tensioning of thedryer fabrics, the space under the singletier dryer group is free. As shown in
Fig. 1, this was already utilized in
Schwedt by installing an intermediate
floor for the waste conveyor belt. The
additional basement space can be usedas roll and clothing store or for secondary aggregates. Not only is the cellar

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

Main components of the Top DuoRun
Rising demands on paper quality makemachine cleanliness very important thesedays. For this reason all the drying cylin-ders are equipped with fold-out doctors
to allow easy cleaning of the surfaces.
The fabrics in the first dryer groups
are cleaned continuously by DuoCleaners
during operation.

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

27

Fig. 3:
Duostabilizer.

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

The ropeless tail transfer system isreliable and trouble-free. Tail removalfrom the cylinder surface and attachment
to the dryer fabric is assisted by air blow
nozzles. Transfer in the drying section via
the DuoStabilizer transfer zone and drilledroll is likewise assisted by air blowers.
This system is simple and maintenancefriendly, and due to the short intermittent
blower cycles air consumption is low. At
the end of the dryer section the web is
supported on the last drying cylinder, andcut by a water jet.

Together with the drilled guide roll, the
DuoStabilizer 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 outgoing
fabric and box and in the fabric guide rollis provided by the DuoStabilizer, which isconnected to a vacuum system. The gap
is sealed at the top of the DuoStabilizer
by a felt seal across the web and by airjets at the sides. The felt seal folds away
to allow changing of the dryer fabrics. On
the operator side a transfer zone 500 mm
long is incorporated in the DuoStabilizer
and drilled roll. During the transfer procedure vacuum is applied to the transfer
zone only. The amount of air to besucked out in the DuoStabilizer is relatively small compared with the suction
guide-roll, since the felt seal keeps out
the air entrained with the fabric. Furthermore, the DuoStabilizer vacuum connection is not limited by the bearing

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

Comparison of electrical energy consumption shows that the DuoStabilizer/
drilled roll combination uses about 70%
less energy than a suction roll, and about
60% less than the web stabilizer/grooved
guide roll combination. Vacuum measurements on DuoStabilizers in production
machines gave the following results:

In gap between outgoingwire and box

70-250 Pa

In dryer wire suction
guide roll

250-700 Pa 3

In gap between incoming
wire and box

10-30 PaThe use of DuoStabilizers allows the evaporation distance between cylinders to beextended by up to 30%, without changing
the roll diameter.

The DuoCleaner (Fig. 4) is a fabric cleaning device operated by water under highpressure. Dirt is removed mechanically,
and the vacuum zone around the water
nozzle sucks away the water and dirt particles rebounding from the fabric.

The DuoCleaner operates at a pressure of
200 to 300 bar and uses very little water(about 0.7 litres/min). This means that it
can be used continuously throughout
production. Even at low basis weights,
there is no visible interference in theweb. At the present time the DuoCleaner
is used very successfully for basis
weights between 35 and 160 g/m 2. It
keeps the dryer fabric clean and thus
helps to improve water evaporation on theside of the web away from the cylinder.
This increases drying capacity and reduces web curling. Installed on a testliner
machine, it was found that the DuoCleaner rapidly increased the air permeabilityof the dryer fabric from 270 to 375 cfm(new condition: 400 cfm).
Since shutdowns are not required for
fabric cleaning, machine runability isimproved and these components soon
pay for themselves.

28

Fig. 4:
DuoCleaner fabric cleaning device.

Features of the Top DuoRun
Stable running
After leaving the last press nip, the web
is sucked on to the fabric of the first dryer
group and fixed. It is then supported on
the fabrics right through the dryer section, thus ensuring stable running andreducing the risk of a break rupture to aminimum. The combination of DuoStabilizers and dryer fabric drilled guide rolltransports the web reliably from cylinder
to cylinder.

At the cylinder runout point the DuoStabilizer fixes the web by suction on the dryer fabric. The vacuum balances out thecentrifugal force around the drilled guideroll and thus keeps the web fixed to thedryer fabric.

High specific evaporation
Thanks to the high specific evaporation,
dryer sections are shorter and investment costs lower. To increase the heattransfer from steam to web, all cylinders
are fitted with spoiler bars. In order toreach such a high evaporation capacity,
the heated web must be able to dry out
sufficiently after leaving the cylinder. To
this purpose the DuoStabilizer provides along evaporation distance. Since most of
the evaporation takes place below thecylinder in the Top DuoRun, hot air blow
pipes are installed at this point. These
blow pipes are dimensioned so that more
fresh air is blown into the centre of themachine. The moist air then flows equally
toward the operator and drive sides ofthe machine, thus removing the water
vapour on both sides to ensure a uniform
humidity profile.

High availability
The Top DuoRun ensures high availability, with short down times and consistently high paper quality. Its stable running characteristics reduce web breakfrequency to a minimum. A significant
advantage of this cylinder arrangement is
the short tear-off time required. Waste
material falls on to the conveyor belt
below and is transportet automatically tothe pulper. As a result, time-consuming
removal of waste from the drying section
is no longer necessary. The ropelessedge strip transfer system ensures fastand reliable transfer, without any time
wastage due to rope wear or breakage.

Controlled paper shrinkage
Due to the rising web temperatures at the
beginning of the dryer section, the initial
wet strength falls off and web extension
increases. When the web is tensioned, it
extends in the longitudinal direction andits width shrinks.

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

4

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

Paper Machines

29

Fig. 5:
V-Top DuoRun.

5means of short dryer groups at the end of
the dryer section, allowance can be madeby speed adjustments for web shrinkage,
thus preventing breaks.

Prevention of curling
One-sided drying makes the web tend tocurl. This curling tendency is caused in
the dryer section by unequal water distribution between the top and reverse
sides of the web, which therefore curls
toward the most recently dried side.
Tests on paper machines in practice haveshown that curling can be controlled
quite precisely by adjusting side-to-side
humidity distribution. This can either bedone in the drying section or afterwards.
According to these tests, one-sided drying has no effects on other paper characteristics.
The first Top DuoRun will start up in
Sweden early in 1996 on a newsprint
machine designed for an operating speedof 1800 m/min.

V-Top DuoRun
The V-Top DuoRun (see Fig. 5) was
developed in order to minimize paper
machine investment costs. It likewisecomprises a single-tier dryer section,
but arranged in vee-form. At the beginning and end of the dryer section shorthorizontal dryer groups can be installed.
The vee-configuration is more compact
than the horizontal arrangement, andallows more effective utilization of space
below the drying section.

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

30

Paper Machines Division:
Coating with the JetFlow F
JetFlow F is the name of our new bladecoater generation. The new Voith Sulzer
blade-coater was developed to maturity
in
only
three
years, and is now
well-proveninpractice.
With
enormous potential for output andproduct
quality,
the JetFlow F sets
new standards inthe paper industry.
If we were to
adopt
Olympics
terminology,
we
The author:
could
say
that
the
Bernhard Kohl,
JetFlow goes fastApplicationengineering coaters
er, higher, further
and cleaner – inother words:
I This coating machine runs faster(better runnability)
I Coating quality is higher than withother types
I It has wider applications than othertypes
I It uses jet-sizing – the cleanest way tocoat paper.

considerable brain-storming between
customers and engineers to make it
feasible. In order to put the idea down on
paper – literally – we converted our pilot
machine in Heidenheim accordingly.

This article summarizes the development
and technology of the JetFlow F. As shownby experience, the success of this new
blade-coater is due to a complete understanding of the principles and interrelationships involved.

1. Basic principle
In the early 1990s, a well-known USA
paper producer had a good idea – todevelop a free jet coater for a predetermined coating thickness, evened out by ablade. This idea was not new, but it took

2. Development
After innumerable tests, rebuilds andoptimizations, the JetFlow F was finallyborn. Parameters such as jet angle,
length, velocity and consistency for theright coating quantity and pressure were
worked out. A significant feature is thecurved outflow lip (patented) resulting
from this development work. At the sametime a coating deaerator was developed
for this system which likewise improves
all other free jet coaters.

3. Trials
In May 1993 the first two JetFlow F coaters were installed in the USA. Right fromthe outset, they met all quality demands
for fine papers – although the coating
formulations used here had been developed and optimized over some decades
for roll-type coaters.
This was where the customer contribution to development work really started.
If the JetFlow F could meet roll-type coating quality with these formulations, what
quality levels might it reach with formulations optimized for jet-sizing? – Better ones!

4. Results
Many paper producers are interested in
the JetFlow F because they have problems with their existing coaters. Exhaustive tests on the Heidenheim pilot coatingmachine have proved the versatility of the
JetFlow F, and market acceptance is shownby the following reference list (Tab. 1).

Tab. 1: JetFlow F Reference list
width
mm

speed
m/min

2 JetFlow F OffCM

3680

1070

80-200 g/m 2
single and double coating

Biron PM 24
USA

1 JetFlow F OnCM

3680

762

LWC
60-80 g/m 2

Plattling SM 11
Germany

2 JetFlow F OffCM

7610

1550

LWC
35-70 g/m 2

Gratkorn SM 9
Austria

2 JetFlow F OffCM

6450

1250

80-240 g/m 2
single and double coating

Kuusankoski PM 7 2 JetFlow F OnFinland
CM

4660

900

60-150 g/m 2
Precoating with Speedsizer

N.N.
Finland2 JetFlow F OnCM

7680

1400

LWC + MWC
6-16 g/m 2

N.N. (LOI)
Brazil

2 JetFlow F OnCM

7560

1500

LWC
40-70 g/m 2

Customer

Coating system

Rapids 64
USA

Paper gradesPaper Machines

31

Fig. 1:
Schematic arrangement of the JetFlow F.
Fig. 2:
JetFlow F coating principle.

1

In order to eliminate the air entrainment
problem applying to all other types ofcoater, the coating jet is preceded by adeaeration unit (Fig. 3). In addition, thecurved outlet lip ensures centrifugal mixing of the coating material, so that by thetime it reaches the web it is completely
free of air.

6. Technology
2
The JetFlow F induces no pressure penetration as in conventional coaters, but
dewatering during the dwell time is unrestricted and therefore more uniform. Furthermore, the coating material is more
liquid when it reaches the blade. After
equalizing, the coating structure is thus
better.

7. Clean operation
The JetFlow F is a closed system, andcoat reaches the paper without film
splitting. As a result, coating takes placecleanly without any spray, mist or deposits. Between the nozzle, blade and return
flow plate of an LWC coater, for example,
a mirror-finish film without any stripes
can be seen over a distance of 7 m

Wash waterFS
bypassDeaerator
Pressure filter

DS
Foam pipe

5. Operating principle
A thin coating film is applied in the formof a jet at a defined angle (Fig. 1). Air
entrainment is prevented by the verticalforce component. Since the paper web
moves faster than the jet, the application
area is greatly extended. This makes thefilm much thinner and more uniform thanin conventional coaters, with the following benefits:
I Better cross-profile
I Lower blade loading
I Smaller recirculation flow

Coating colour

Servicetank

Coating colour recovery
Pump

Tab. 2: JetFlow F Applications successfully tested
Raw paper:– wood-free– wood-containing

50 - 140
28 - 290

g/m 2
g/m 2

Coat weight

4.5 - 17g/m 2

Speed range

330 - 1800

m/min

Solids content(4)50 - 70

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

through the machine at 1500 mpm. The
range of applications tested so far on
the 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.

32

Finishing Division:
The Janus Concept –the future of paper finishing
For a number of uncoated and coatedpaper grades, softcalenders installed
online and offline are also currently
being used with success for calenderingin addition to the proven supercalenders. The essential challenges forthe future will
be improvementof the efficiencyof the manufacturing process withsimultaneously
increasing quality
requirements. The
experience available for both processes results inthe necessity ofdeveloping completely new calendering concepts tomeet these market requirements.

The following provides a summaryof the arguments
decisive for thedevelopmentofnew calendering
The authors:
U. Rothfuss,concepts.
The
Janus Technology
technical
andtechCentre,
nological possibiland U. Gabbusch,
Developmentities of the new
Janus Concept to
be installed online and offline are presented. In comparison to the classic
supercalender, the exceptional advantages lie in online integration for eachproduction speed, the lower number ofrolls in conjunction with the use of plas-

tic covers, the distinctly lower calendering temperature compared with the softcalender and the considerably lower
energy requirement achieved as aresult.

advantages of the machine calender lie in
its efficient operation, whereby the uniting of these two positive arguments were
the basis for the development of the softcalender, which in meantime has established itself on the market.

Laboratory results will be discussedwith respect to a comparison between
the Janus Concept and supercalenderfor highly compressed paper applications, i.e. LWC-Roto and SC-A, whichshow that the gloss and smoothness
values and printability for such papers
are comparable with the current SCfinish, also for PM and SM speed.

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

Introduction
Until the beginning of the 1980’s, calendering was carried out exclusively bymeans of supercalenders and machinecalenders. While the supercalender isdistinguished by its technological advantages due to the use of elastic rolls, theTable 1 initially shows the calender types
which 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 supercalender, compared with 1-4 individuallycontrollable nips of the softcalender. If
these criteria are transferred to the calendering process, the supercalender isaccordingly provided with considerably
more nips for densification the paper via

Table 1: Comparison between supercalender and softcalenderSupercalender

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/mm 2

31 - 40 N/mm 2Max. surface temperature

100°C

200°C

Roll diameters

smallerbiggerLoad changes

2/revolution

1/revolution

Speed

450 - 900 m/min

PM / SM speed

Finishingpressure and temperature, while in thesoftcalender, a distinctly higher amountof energy has to be supplied for web densification per nip for a comparable calendering result.
Furthermore, it is important to show, on
the basis of Table 1, to what extent thetwo calendering processes additionallydiffer from each other (1).
The table clearly shows why higher calendering temperatures are necessary forthe softcalendering process. The larger
roll dimensions are effecting a wider contact zone, which results in a lower compressive stress being produced based on
a comparable line load compared with thesupercalender.
For a conversion energy comparable withthe supercalendering process, considerably 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, energy
has to be installed for a four-nip online
calender with about 50% more in comparison to two offline 12-roll supercalenders.
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 contrast to the softcalender, where only plastic covered rolls are provided. The advantages of the plastic covers are given by
their higher mark resistance and a better
wear resistance, which finally serve to33

Table 2: supercalender advantages/disadvantages
Advantages

Disadvantages

Many nips with high degreeof coverage

Limited speed range

Good distribution of
calendering work between
load and temperature
Process technically and technologically wellknown for decades
All paper grades can be finishedat high quality
Low amount of energy
to be installed

Online installation not possible
Limited temperature range
Small influence onto two-sidedness
Low efficiency becauseof roll and reel change downtime
Dependence of line load from
top to bottom nip
High space requirementwith additional

Table 3: Softcalender advantages/disadvantages
Advantages

Disadvantages

Online installation possible

Not suitable for all paper grades

Individual controllable single nips

High amount of energy to be installed

Minimisation of two-sidedness

Compression lines problem can occur

Wide load and temperature range

Only few nips

High efficiency because of lessroll changes
For online installations
low space requirement without
add. personnel

ensure a long life time. Cotton rolls bycontrast are subject to a higher mechanical load because of the double loadchange per revolution in the supercalend-er, compared with the plastic covers inthe softcalender. The previously lower
loading capacity of the plastic coveredrolls is an argument which is currently

34

still responsible for the main use of
cotton covers in supercalenders. However, one cannot fail to notice that plastic
covers are increasingly being used insupercalenders, whereby their installation
positions are mainly in the upper calender area. In this connection, a technological aspect resulting from moving to plastic covers should not remain unnoticed.
As a consequence of the internal friction,on account of their larger hysteresis, thecotton covers are subject to a higher
temperature development, which issimultaneously a component of theconversion energy. In the case of plastic
covers by contrast, a clearly lower temperature development is noticed. A
supercalender equipped with such rolls
produces lower gloss and smoothness
values under comparable calendering
conditions as a result.

For the purpose of further clarification,
the advantages and disadvantages ofboth calendering processes are shown in
the Tables 2 and 3 (2).
The list essentially shows that the supercalender cannot follow the current
speeds of modern paper and coatingmachines. The capacity of the standard
two supercalenders is frequently exceeded today. A second or third supercalender involves higher investment costs forbuildings and also add. personnel costs.
The main features of the softcalender are
summarised in Table 3.
Summarised, the main advantages of thesoftcalender are its high efficiency andflexibility, whereby the latter mentioned
feature refers to minimisation of the two-sidedness, due to individually controllable single nips and the wide temperatureand line load range.
It should be mentioned that the successful use of the softcalender in the case of
specific paper grades, e.g. high gloss
qualities, was initially made possible byengineering advances and the additionallycreated preconditions from the papermakers. The latter mentioned includes, inaddition to levelling the cd-profiles, acoating formulation which has been consistently adjusted to the changed conditions of the softcalender.

finish being produced which is comparable to or better than a supercalender.
The task basically represents the totalsynergy between the supercalender andthe softcalender. Because of this double
task, the concept was given the name of
the ancient god with two faces: the Janus
Concept. One face reflects tradition, thesupercalender and the softcalender, theother looks ahead towards new calendertechnology.

Table 4 Janus Concept requirements.
I Finish of all paper grades at

The necessity to reconsider current
calendering possibilities is also underlined by the results of extensive tests
carried out for a highly compressed SC-A
paper (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 of
the chilled iron rolls reach minimum
160°C and the compressive stresses of
all nips are in a range, as are present in
the bottom nip of a supercalender loadedwith 350 N/mm. However, this applies
only to a speed range of about 500700 m/min, i.e. the calendering speed of
the supercalender usual for this type of
paper.

The Janus Concept
Decisive for the development of a newcalender concept was the requirement for
an online installation for any conceivableproduction speed in conjunction with ahigh quality
I online and offline installation

possible
I High efficiency including lessroll changes
I Low space requirement without

add. personnel
I Low amount of energy to beinstalled
I Less energy loss during operation
I Minimisation of two-sidedness
I Wide load and temperature range

The core principle of the Janus Concept
is that only the number of nips necessary
for calendering a specific paper quality isused. Missing nips, which are to beequated with mechanical conversion
energy, are not replaced by thermal energy only. Based on the results of numerous analyses which showed that the highnumber of nips as used in the supercalender is unnecessary for the actual calendering process, a maximum of eight rolls
resulted for the Janus Concept.

35

FinishingFig. 1:Janus Concept with 2 x 5 rolls.
Fig. 2:Janus Concept with 1 x 8 rolls.
Fig. 3:Janus Concept: Formula.

An initial precondition for online integration of the Janus Concept is controllability of paper web threading at full PM or
SM speed. Several years of intensive
tests on a pilot plant, developed specifically for this purpose, showed that web
threading can take place successfully by
a combination of aerodynamic elementswith ropes and belts.

0.86

50

0.1

0.37 0.63
dw ell tim e ms

60
0.9

com

0.76

pre

ssi

55

N/m

˚C

≈

150

0.78

45

ess

0.80

˚C

str

100

ve

0.82

m2

0.84

Bulk cm 3 /g

The question naturally arises as to how
the energy plus of the Janus Concept isachieved compared with the supercalender, since the same result is to beachieved with less nips at a considerably
higher calendering speed.
3bulk [cm 3/g] 1,378 - 0,00356 ·T- (0.00825 - 5,12 ·10 -5T)
p -[0,039 + (0,188 - 0,00112 ·T)p · e -0,093p]t·e -0,421t

The most significant difficulties did notoccur at the beginning as actually expect2
ed with web guidance within the calend- 1
er, but rather with web transfer to thecalender. The control of problem-free
From the wide range of information
This spatial representation is based on
web threading also assumes the drive of
acquired from available supercalenders, a
the equation shown below which makes it
all rolls installed in the calender.
mathematical description of the distribupossible to predetermine the necessary
tion of the calendering work in the nips
calendering temperature and compressiveof a calender could be found with the aid
stress as a function of speed or dwell
Against the background of the finish,of extensive analyses.
time for any number of nips. In principle,comparable with the supercalender inthis equation describes nothing else than
conjunction with minimum two-sidedFigure 3 shows the calendering range ofthe influence of these parameters on, e.g.
ness, one solution could be the division
the Janus Concept in three-dimensional
the bulk of a paper. Equations can natuof the supercalendering process into twoform. Illustrated in this case for the 8-rollrally also be used in a similar form forprocesses, represented by the two
version, for example, is the bulk of a
specific gloss or smoothness values forstacks, consisting of 5 rolls respectively.
SC-A paper, applied to the Y-axis, as a
the respective customer product, i.e. for
Additionally it was examined how a single
function of the dwell time, applied to thethe respective paper quality.
stage solution with 6-8 rolls could meet
X-axis and compressive stress, applied to
all requirements. Like the supercalender,
the Z-axis. As curved surfaces in space
a roll reversing nip must also be provided
the bulk at 100 and 150°C surface temThese calculations result, particularly infor two-sided calendering. The twoperature can be seen.
the case of papers to be highly comsidedness can be controlled by influencpressed, in necessary nip numbers
ing the increase of line load nip by nip,which a softcalender can normally notusing different roll materials and precalprovide.
0.88
culated nip widths.
In order to make this “multi-nip online
calendering process” possible, a whole
series of technical elements are necessary. The most important features of theJanus Concept are accordingly listed inTable 5.

36

Due to the considerably smaller rolls andhigh line loads compared with the softcalender, compressive stresses up to
60 N/mm 2 can be realised in the Janus
Concept, whereby the development ofsuitable plastic covered rolls took placeat the same time. The new roll generation
withstands the high mechanical and thermal loads whilst maintaining the familiar
advantages of low sensitivity to marks
and high wear resistance, which ensuresa long life time.

Table 6: Energy balance Janus Concept – softcalender – supercalender
4-Nip Softcalender
2 Supercalender
Janus Concept
installed consumed installed consumed installed consumed
Heating
capacity

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

400 KW

950 KW

440 KW

260 KW

140 KW

0 KW

720 KW

360 KW

0 KW

0 KW

Power for units 520 KW
Power
for winder
Total kW

0 KW

8140 KW 5640 KW

6220 KW 3700 KW

4600 KW 3150 KW

Table 5: Janus Concept – Features
I High-speed open-nip threading

systemI All rolls driven

its own control loop. Thus, a total of four
control elements are available for thermal
reduction of two-sidedness.

I New generation of plastic

covered rolls
I Midrange-heated intermediaterolls with new type of surface
treatment
I Heated top and bottom roll
I Individual temperature control
of all thermo-rolls
I Lever-type calender withoverhanging load compensation

In addition to increasing the mechanicalconversion energy, the proportion ofthermal energy also had to be adapted to
the new concept. By using new types ofheat rolls, surface temperatures of about
150°C with minimum cd-profile deviations are achieved. Each roll is allocateda separate temperature control loop. The
oil-heated deflection compensation rollsin the top and bottom position permit
surface temperatures of about 130°C,
whereby each roll is similarly allocated

The Janus Concept accordingly moves ina temperature level above the supercalender, however, distinctly below the temperatures necessary for the softcalender.
In conjunction with the considerably
smaller roll diameters compared with thesoftcalender and utilization of thermalenergy of a heating roll in two nips, theheating capacity to be installed is drastically reduced and the heat losses to theatmosphere are considerably reduced aswell. Table 6 shows the capacities to beinstalled, as well as the energy consumption of the Janus Concept in comparison
to an online 4-nip softcalender or two
12-roll offline supercalenders for anassumed machine width of 8 m.

For the two calenders to be installed
online, the Janus Concept and softcalender, an operating speed of 1200
m/min at a design speed of 1400 m/min

was taken as a basis. For the supercalender an operating speed of 800 m/min
respectively at a design speed of 1000m/min was taken as a basis.

Assumed as maximum surface temperatures were 85°C for the supercalender,
150°C for the Janus Concept and 200°C
for the softcalender. The maximum line
loads are about 400 N/mm for the supercalender, about 550 N/mm for the Janus
Concept and about 370 N/mm for thesoftcalender.
The table clearly shows that the Janus
Concept has an approximately 15% lower
energy requirement compared to two
supercalenders, and an approximately
44% lower energy requirement comparedto the softcalender. The Janus Conceptalso has significant advantages for theenergies to be installed: 26% less than
the supercalender and 45% less than thesoftcalender.
Further essential features of the Janus
Concept are in the consistent realisation

37

FinishingFig. 4:
Line load characteristic of the Janus Concept incomparison to a conventional or compensatedcalender.
Fig. 5:SC-A grade 56 g/m 2, gloss vs. line load.

In conjunction with the achieved weight
reduction of 50% for the elastic rolls, theweight compensation distinctly increases
the operating capacity of the Janus Concept. With comparable line load in thebottom nip, the overhanging load compensation and reduction of the rollweights as such enables a distinctly higher line load in the above located nips, i.e.
the line load characteristic from bottom
to top becomes steeper. Figure 4 shows
the line load range of each individual nipof the Janus Concept in comparison to a

the relatively limited range of the supercalender.
The available high compressive stress,
the steep line load characteristic, as wellas the temperature range up to 150°C
when using seven nips, create the precondition for calendering virtually all
paper grades at the respective PM andSM speed, based on the Janus Concept.
5

The test results achieved according to theJanus Concept with SC-A paper and LWC
paper for rotogravure printing are discussed in the following. A laboratory
calender with all features of the Janus
Concept will be commissioned in thesummer of this year and will be available
for customer tests from autumn onwards.

Number of Nips

5
7
9
11
0

50

100

150

200

250

300

350

400

Line Load N/mm
conventional Supercalendercompensated Supercalender
JANUS CONCEPT

4conventional calender or a compensatedcalender.
The steeper the line load characteristic,
the less the line load differences are
between the bottom and top nip, which
has a positive effect on the reduction of
the two-sidedness (4). Clearly distinguishable is also the enormous line load
range of the Janus Concept compared to

350

450

550

250

350

Line Load N/mm
JANUS CONCEPT: 120° C, 650 m/min
JANUS CONCEPT: 120° C, 1000 m/min
Supercalender: 70° C, 650 m/min

79
76
73
70
67
64
61
58
55
250

350

450

550

250

350

Line Load N/mm
JANUS CONCEPT: 120° C, 650 m/min
JANUS CONCEPT: 120° C, 1000 m/min
Supercalender: 70° C, 650 m/min

6

1
3

54
51
48
45
42
39
36
33
30
250

Printgloss Gardner %of the constructive functional units of
the new lever-type calender generation
with overhanging load compensation,
which considerably improves the qualityof line load distribution in the individual
nips.

Gloss Gardner %Fig. 6:
SC-A grade 56 g/m 2, printgloss vs. line load.

Calendering of SC-A paper acc.
to the Janus Concept
The tests were carried out with a European standard SC-A paper. The basis weight
was about 56 g/m 2, the ash content was
about 31%. These papers are currently
being calendered with the addition of
steam on two 12-roll supercalenders at
250-280 N/mm line load and about
70°C surface temperature at 650 m/min.
The following results show a comparisonof the standard supercalendering process
to the Janus Concept, whereby in thecase of the Janus Concept, both the current calendering speed of 650 m/min as
well 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.

One can see that the gloss of the paper
supercalendered at 650 m/min is exceeded by the Janus Concept even at a PM
speed of 1000 m/min at 120°C surface
temperature and line loads of about
350 N/mm. The calendering temperature
which is 50°C higher compared to thesupercalendering process, has a strongly
positive effect on the gloss result in thiscase. Figure 6 appropriately shows theprint gloss of samples printed by the
rotogravure process.
For the print gloss, virtually the same
correlations can be seen as previously
discussed for the paper gloss. At
350 N/mm line load, the print gloss of
paper supercalendered at 650 m/min canbe exceeded, even at a PM speed of1000 m/min. Figure 7 shows the roughness PPS-10 S over the line load.

38

Fig. 7:
SC-A grade 56 g/m 2, roughness vs. line load.
Fig. 8:SC-A grade 56 g/m 2, bulk vs. line load.

1.5

0.86

1.4

0.84

Bulk cm 3 /g

Roughness PPS-10 S µm

Fig. 9:SC-A grade 56 g/m 2, blackening vs. line load.

1.3
1.2

printability comparable to that of SC
paper with less blackening.

0.82
0.80
0.78

1.1

0.76

1.0
250

350

450

550

250

250

350

350

450

550

250

Line Load N/mm

Line Load N/mm

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

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

8

The diagram clearly shows that theroughness of the supercalendered comparison paper by means of the Janus
Concept could be achieved at a comparable calendering speed of 650 m/min atline loads of about 450 N/mm. However,
due to the surface temperature of only
120°C in this case, this was not completely possible at a PM speed of 1000m/min. Figure 8 shows the densification 9
or bulk as a function of line load.

One can see that the compression of thesupercalendered paper by the Janus Concept at 450 N/mm line load is alsoachieved at a PM speed of 1000 m/min.
Based on knowledge from earlier tests
that the printability of such paper wasless correlated with smoothness orroughness rather than with densification,
a comparable printability was also to be
expected in this case (5).
The respective rotogravure tests carriedout confirmed this in all respects. Bothfrom a visual assessment aspect and also
from the number of counted missing-dots
in the quarter-tone range, no differencesof the supercalendered paper to theJanus Concept calendered samples were
to be seen.

Blackening Index %

7

350

60
58
56
54
52
50
48
46
44
42
40
250

350

450

550

250

350

Line Load N/mm
JANUS CONCEPT: 120° C, 650 m/min
JANUS CONCEPT: 120° C, 1000 m/min
Supercalender: 70° C, 650 m/min

A further important criterion, particularlyin the case of SC-A papers, is the socalled 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 of
an image analysis system developed at
the Technical University in Darmstadt, it
was possible to measure the blackening
in the form of a blackening-index, whereby the larger percentage figure indicatesmore blackening. The respective results
are summarised in Figure 9.

One can clearly see that the blackening
index is lower in the case of papers
calendered according to the Janus Concept. This means that the Janus Concept
enables paper to be calendered with a

Summarised, this test shows that theJanus Concept is capable of producing
with only seven nips at maximum
450 N/mm line load, even at PM speed,
a paper with a printability comparable
to that of the supercalender with lessblackening and a simultaneously higher
print gloss.

Calendering of LWC-rotogravure paper
according to the Janus Concept
The tests were carried out with a European standard LWC rotogravure paper. The
basis weight was about 58 g/m 2 the coating weight was about 9 g/m 2 per side.
The papers are currently being calendered on two 12-roll supercalenders at
270-300 N/mm line load and about 65°C
surface temperature at 700 m/min.

The following results show a comparisonof the standard supercalendering process
to the Janus Concept, whereby in thecase of the Janus Concept, both thecurrent calendering speed of 700 m/min
as well as the coater speed of 1400
m/min are taken into account. Figure 10
initially shows the paper gloss Gardner
as a function of line load. One can seethat the gloss of the paper supercalendered at 700 m/min is exceeded by theJanus Concept also at an SM speed of
1400 m/min, 135°C surface temperatureand 350 N/mm line load.
Figure 11 appropriately shows thesmoothness Bekk. The diagram clearlyFinishing

39

Fig. 10:
LWC-roto 58 g/m 2, 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/m 2, bulk vs. line load.

Figure 12 shows for the sake of completeness also the roughness. Measured 11
according to PPS-10 S, the roughness ofthe paper supercalendered at 700 m/min
by the Janus Concept at 1400 m/min and
135°C surface temperature is alreadyexceeded at line loads of 350 N/mm.

3500

Bulk cm 3 /g

Smoothness Bekk s

4000

3000
2500
2000
1500
1000
250

350

450

550

250

0.86
0.84
0.82
0.80
0.78
0.76
0.74
0.72
0.70
250

350

350

450

550

250

Line Load N/mm

Line Load N/mm

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

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

350

13

Roughness PPS-10 S µm

shows that the Bekk smoothness of thesupercalendered paper by the Janus
Concept at double the speed of
1400 m/min at 135°C surface temperature and 350 N/mm line load is virtuallyreached and already exceeded at
450 N/mm line load.

0.85
0.80
0.75
0.70
0.65
0.60

Gloss Gardner %

250
350
450
550
250
350
Figure 13 finally shows the densification
Line Load N/mm
or bulk as a function of line load. The diaJANUS CONCEPT: 135° C, 700 m/min
JANUS CONCEPT: 135° C, 1400 m/min
gram clearly shows that the bulk of theSupercalender: 65° C, 700 m/min
paper supercalendered at 700 m/min cor- 12
responds to the sample calenderedaccording to the Janus Concept at 1400
already to be expectedfrom the calenderm/min, 135°C surface temperature anding results, no differences in the printability of the samples supercalendered at
700 m/min to the samples calendered
70
67
according to the Janus Concept at
64611400 m/min, whereby the latter were
58
55
characterised by a higher print gloss
52
49
due to the higher calendering tempera46
43
ture.
40

With this new calendering technology,
papermakers are provided with an instrument which fully meets the initially mentioned requirements for calendering highquality papers in “supercalender quality”
also at PM or SM speed with highefficiency and distinctly reduced energy
consumption.

250

350

450

550

250

350

Line Load N/mm
JANUS CONCEPT: 135° C, 700 m/min
JANUS CONCEPT: 135° C, 1400 m/min
Supercalender: 65° C, 700 m/min

10350 N/mm line load, i.e. calendering conditions under which more favourable
gloss and roughness values could beachieved by the Janus Concept.
The rotogravure printing tests carried out
for this comparison showed, as was

Summarised, this test also shows that
the Janus Concept is capable of producing with only seven nips but double thespeed at 350-450 N/mm and 135°C surface temperature, a paper which is absolutely comparable with the supercalendering process. Both these tests basedon the example of the highly densified
paper grades, SC-A and LWC rotogravure, impressively show the enormous
potential of the Janus Concept.

References(1) Rothfuss, U. – A review of surface characteristics andprinting results from soft and supercalendered papers. TAPPI
Finishing Conference, Chicago 1994
(2) Marleaux, H.P., Cramer,D., Kathan, C. – Von Matt bis
Hochglanz – Praxiserfahrungen mit On-/Offline-Softkalandern
für gestrichene Papiere. Wochenblatt für Papierfabrikation
122 (1994), Nr. 8, 296 – 301(3) Rothfuss, U. – Inline- und Offline-Satinage von holzhaltigen, tiefdruckfähigen Naturpapieren. Wochenblatt für Papierfabrikation 121 (1993), Nr. 11/12, 457 – 466(4) Bresser, H., Kayser, F. – SNC – Der Superkalander der
90er Jahre. Das Papier 43 (1989), Heft 10A, 169 – 182(5) Dr. Lesiak, M., Rothfuss, U. – Online-Satinage von altpapierhaltigen SC-Papieren. 25. EUCEPA Conference, Wien 1993

40

Service-Division:
Paper machine condition analysis
Paper machines are designed for specificproduct types and defined output capacities. They are also optimized for adefined mechanical loading, both staticand dynamic. There is a growing demand
among operators for modernizing oldpaper machines as
far as possible. The
goal is to achieve
betterproduct
quality and greater
outputthroughhigher operating
speeds. However,beforefinalizing
the new production
parametersamachine condition
analysis
surveyshould be carried
The author:
Andreas Arnhold,out. By establishMeasuring anding the detailed
Diagnostics Service
condition of theRavensburg
papermachineand its environment, conclusions can be
drawn as to how far existing components
can meet the new requirements.

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

Against the background of worldwide references, and together with the technicaldepartments of the product divisions theengineers of the Voith Sulzer Paper Technology Service Division carry out condition analyses on all kind of paper

machines, for example in connection withproject feasibility studies.

1. Condition analysis
by means of measurements
Before an old machine can be upgradedfor higher output, mechanical loading
limits have to be analysed above all. Evenfor establishing new production parameters and modifying the operating range
of individual components – which can now
be done by computer methods – basic
data is still essential. Extensive measurements are often required in order to analyse existing operating conditions andpossible improvement potential without
excessive modifications.

1.1 Approach flow section analysis
The starting point for condition analysis
is generally the approach flow section. To
ensure faultless product quality, thestock suspension and so the fibres
flowing out of the headbox have to be
distributed as uniformly as possible on
the wire. Pressure pulsations originating
among other sources from rotatingmachines in the approach flow section
play a decisive role in this. These pressure pulsations are therefore measured atseveral points between the cleaners andheadbox, using special sensors inserted
in the piping. A frequency analysis may
then be carried out to detect the main
disturbances generated by the fan pumps
or screeners.
If various products with different basis
weights are manufactured on the machine,these measurements are normally repeated for each product. The resultant data
and absolute pressure measurements areused for assessing the approach flow layout. In addition, various paper samples
are taken in order to analyse the effect ofpressure pulsations on longitudinal andcross-machine profiles.

1.2 Mechanical vibration analysis
A significant proportion of condition
analysis investigations involves measuring mechanical vibrations on the paper
machine itself. Measurements are firstcarried out at highest possible operating
speed on the headbox, wire and press
sections and reel winder to assess vibrations occurring during production. These
basic readings initially indicate any disturbances originating from shaker
systems, 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 optimize
machines for which no rebuild plans have
yet been made.

One of the main goals of condition analysis is to predict mechanical behaviour
at higher operating speeds. This means
locating critical operating points or resonance conditions in the rolls, transmission and gear systems, framing and foundations. The mechanical behaviour of all
machine sections is therefore analyzed at
different speeds. Ideally, each group isaccelerated to full speed several times insuccession in order to record dynamic
characteristics over the entire speedService

41

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

1

42Fig. 2:Vibration measurements:
An average of 100 measuring points are required
for machine analysis from headbox to drying
section on both front and drive sides.
Fig. 3:The measured frequency spectra are displayedin the form of waterfall diagrams as a function ofmachine operating speed.

It goes without saying that such measurements cannot be carried out during
normal operation, but have to be scheduled for long shut down periods. Carryingout this kind of vibrational analysis on an
entire Fourdrinier machine, from headbox
to the last drying section on both thedrive and front sides, needs about 100 2
measuring points (Fig. 2) with a time
outlay of 15 to 20 hours. The frequency
spectra thus measured are displayed foreach point as a function of machine
speed in the form of waterfall diagrams(Fig. 3). These indicate not only thelocation of critical conditions, but also
any out of balance conditions in rolls,
etc. By carrying out a trend analysis
on amplitudes, the highest permissible
operating speed from the mechanicalstress point of view can be determined.
If necessary, these measurements arecomplemented with numerical computer3
simulations.

In addition to this, vibrational analyses
are carried out on the guide rolls in thewire, press and drying sections. Representative rolls are selected in each section and tested for resonance behaviour 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 establish the vibrational behaviour of guiderolls under the installed condition. This

Vibration velocity [mm/s]

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

8
6

800

4

d
ee
sp
e
n]
in
ch /mi
Ma [m

600

2
0

400
0

20

40

60

80

100

Frequency [Hz]indicates whether larger rolls are
required at certain positions to allow forhigher operating speeds.

1.3 Other analytical measurements
Old machines often incorporate levertype presses, whose actual pressing
force is not usually known exactly. Thisdata deficiency is remedied by using
load cells which measure the pressing
forces transmitted via the supports. By
recording a loading and unloading char-acteristic, the hysteresis component canbe determined and hence the friction in
the loading system. For example, by thiskind of measurement it was possible tolocate a defective hydraulic cylinder.
Additional nip impressions are also
evaluated at various line force settings, inorder to assess line force profile uniformity as well.

With modern computerized measuring
techniques, the temperature profile over
the web width can be determined usingService

43

Fig. 4:
Selected rolls are tested for eigenfrequency
behaviour using a special impact hammer.
Fig. 5:
Thermographical measurements:
Even the finished paper reel can be checked
for uniform drying over the entire web width.

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

1.4 Air system analysis
Air system measurements are carried out
on supply and exhaust air in the drying
section, in order to assess air and waterbalances. For this purpose sensor pockets
have to be installed in the piping,
upstream or downstream of the various
branching points, for determining waterand dry air flows. Likewise in the steam
and condensate system, extensive measurements have to be carried out forassessing steam quantities, temperatures, pressures and flow velocities.
4
Based on this comprehensive data, conclusions can be drawn for optimizing piping layout and energy consumption.

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

44

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

higher operating speeds. If a substantial
speed increase is planned, grease lubrication may have to be replaced with anoil lubrication system, or high-temperature 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 up
to higher output without reducing run6
nability.

At higher speeds long press levers are adisadvantage since they are prone tovibrate, for example, and fixed doctors
are also unsuitable. Depending on thedrive concept, gearwheels must be carefully checked particularly in the drying
section. Data in relation to this is available from the vibration measurements
carried out previously, since worn or
damaged gear tooth flanks generate a
special kind of vibration pattern. A visualcheck is still carried out on individual
7
gearwheels, however, and the clearance
between 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 wall
thickness of structural components suchas frames and levers may be seriously
affected (see Fig. 8). For this reason theresidual wall thickness at critical points
must be carefully measured. These 8

Service

measurements are usually carried out by
ultrasonic methods.

3. Electric motors and drives
Speed increases on old machines areoften limited by existing drive and transmission concepts. Even if individual
drives are already installed, it may not be
possible to increase motor capacity.
Initially this can be checked by measuring the motor current consumptions,
speeds and temperatures during normal
operation, and comparing them withdesign data. In case where motor speed
is the limitation, the problem can usually
be solved by using different gear ratios
to keep the motor speeds within thedesign range while increasing the speedof the rolls. In cases of doubt Voith
Sulzer may also consult the drive manufacturer.

4. Vacuum system analysis
Increasing the machine output generallymeans that vacuum requirements will behigher for the suction rolls and devices in
the wire and press sections. Here again,
Voith Sulzer takes comprehensive measurements of all vacua and flows involvedin order to analyze the vacuum system
concept. The most important aspect
here is to check vacuum pump capacities
versus design characteristics. Thisshows whether the higher capacity canbe met by existing equipment or if new
pumps are required. Conclusions are also
drawn with regard to the design of felt
suction units (number and width of slots)
and the interconnection of individualcomponents.

5. Summary
Condition analysis serves not only for
optimizing paper machinery, but also
gives indispensable information on thepossibility of capacity increases, which
normally mean higher operating speeds.
Based on comprehensive measurements
and technically well-founded prognoses,
upgrading potential is assessed and any
critical components or weak points arelocated. Machine condition analyses arenearly always a combination of extensive
measurements and visual inspection.
The most important criterion are themechanical loading limits on the various
components in each section of themachine. These are mainly assessed byvibration measurements, which are therefore an indispensable part of the analysis
procedure.

These fundamental analyses are complemented by further investigations with aview to process optimization. Apart frompurely mechanical inspection and measurements, Voith Sulzer, as an experienced
plant manufacturer, is also in the position
to assess the entire papermaking process. Apart from the approach flow section layout this covers the dimensioningof the vacuum system as well as ofelectrical and mechanical drives. A
comprehensive single-source service isthus available which not only reveals
weak points but above all indicatespossibilities for optimizing machine runnability and improving productivity.

45

46

1

Research and Development

47

Research and Development:
The Voith Sulzer Paper Technology
R & D centres
Since the founding of Voith Sulzer Paper
Technology in 1994, group R&D capacities have been extended with additional
facilities at various locations. According
to the specialization of VSPT divisions,
the working areasat each research
centre were likewise
re-defined.
Parallel work at
different locations
has now been
eliminated, and thecapacities
thus
freed are now concentrated on specificresearch
activities. As a
The author:
result, customers
A. Meinecke,
now have specialR esearchists at their dispoand Development
sal for solving
Heidenheim
problems in every
area of paper technology, together with
the necessary test facilities and measuring systems.

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

This article presents the VSPT R&D centres and describes their work. In a later
edition of “twogether” we shall be reporting on research projects of particularinterest (see table for summary of R&D
facilities).

Voith Sulzer Paper Technology research and development facilities

USA
Germany

BrazilWorking area

Location

Stock preparation

Ravensburg / Germany
Appleton, Wisconsin/USA

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

Coating Technology

Heidenheim/ Germany

Finishing

Krefeld / Germany
Manchester / Great Britain

Winder Technology

Heidenheim / Germany

Heidenheim
At the Heidenheim research centre, development work is concentrated on paper
production, ranging from headbox tosheet processing. This centre is also
responsible for research and development in printing and writing paper production. Detailed development work is
carried out on special facilities for eachcomponent, such as headboxes, sheet
formation and drying systems. The following facilities are available for interrelated process stage testing:
I For sheet formation and press trials, a

total of four test paper machines withvarious sheet formation and press concept configurations. These cover a
speed range of 20 to 2000 m/min, with
web widths of 0.5 and 1 m.

I A

test coating machine with various
coating and equalization processes anda Speedsizer. Working width is up to
0.85 m and maximum speed is currently 2000 m/min.

I A trial roll cutting machine with vari-able geometrical configuration, for
operation e.g. as two drum or as a one
drum winder.

Numerous development laboratories andmeasuring facilities are likewise available.

48

Fig. 1: (page 46)
Heidenheim: pilot paper machine for printing and writing grades.
Fig. 2:
Heidenheim: test coating machine.
Fig. 3:
Heidenheim: test roll-cutting machine.
Fig. 4:Ravensburg: test paper machine for paperboard and packaging papers.
Fig. 5:
Pilot paper machine for packing and board grades.

Ravensburg
Research work in stock preparation 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 incorporates
all the main process stages such as pulping, screening and cleaning, flotation,
disperging, refining, bleaching and thickening, including loop water treatment.
Various complete stock preparation concepts or sub-processes can be tested
here under mill conditions. Likewise customized stock preparation concepts canbe studied and optimized. The extensive
laboratory facilities ensure rapid evaluation of stock analyses and other measurements in the various process stages.
2

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

3

Research and Development

4

5

49

50

Fig. 6:
Krefeld: Finishing Division technology centre
with soft nip calender.
Fig. 7:
Krefeld: test calender for high surface finishing.
Fig. 8:
Appleton, USA: technology centre mainly for
waste paper recycling.
Fig. 9:Appleton, USA: test deinking plantwith flotation cells.

6

7

Krefeld
Here at the headquarters of the Finishing
Division, R&D work is carried out on
calendering. The main components ofcalenders are tested on special facilities,some of which are equipped withextremely high-resolution measuringsystems. Sophisticated computer simulation programs are coming into generaluse for replacing or shortening some of
the more time-consuming experimental
work. For various calendering processes
such as soft calendering or supercalendering, comprehensive facilities are available which are fitted with the associatedequipment for humidifying, preheating,etc. These allow calendering systems andparameters to be selected and optimized
for customized requirements. The latest
installation here is for carrying out tests
on the Janus concept. Other calendering
test facilities are available for customer
trials at Hunt & Moscrop in Manchester,
England.

Appleton, Wis., USA
The waste paper recycling quota is likewise rising in North America – particularly for manufacturing printing and writing
papers. For stock preparation tests, withspecial emphasis on waste paper, a complete line with all the various process
stages is available in Appleton. These
range from pulping, screening, cleaning
and flotation to disperging, bleaching,
thickening and loop water treatment.
Tests and optimization trials can thus be
carried out under mill conditions on nearly all stock preparation processes. Stockcan also be prepared from customers'
raw materials according to special

Research and Development

8

9

51

52

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

requirements – in large quantities if necessary – for carrying out tests on production machines. Extensive laboratory facilities are available for evaluating test
results.

São Paulo, Brazil
This is the latest VSPT research anddevelopment centre, where a trial tissue
machine with a working width of 1 m isinstalled. This machine incorporates thefollowing modules: single or multilayer
headbox, various twin wire configurations for sheet formation, a crepe cylinder with presses and reeler. The machineis completed by a stock preparation line
so that the effects of special raw materials on tissue quality can be investigated.
An ambitious target here is the introduction of new processing stages which will
have significant effects on tissue production in future.

10

Corporate News

53

PAPER INDUSTRY PRESS CONFERENCE IN HEIDENHEIM

Workshop, symposium
birthday party:

andcerned, information is everything”.

At the end of September
1995, international journalists
and German business pressleaders met in Heidenheim
at the first VSPT paper industry press conference. The
motto on this Voith Sulzer

Does this joint venture
between former competitors
really work? Is the new company accepted on the market?
What about the present situation and future goals? The
positive answers to all suchquestions impressed even themost experienced journalists– for the combined forces of
this
joint
venturehave
brought some notable innovations which are making theirmark among customers.
“The Voith Sulzer marriage inpaper technology is working
fine. The future looks promis-

Paper Technology anniversary
was “twogether future forpaper”.
The conference got off to a
ceremonial start with abaroque trumpet concerto in
Neresheim Abbey church –part of the Benedictinemonastery’s ninth centennialcelebrations.
Hans Müller, President andCEO (seen above with Kevin
Chang of Paper Asia) had
every reason to be content: all
the VIPs of international paperindustry
journalism
werepresent on this memorable
occasion. The entire VSPT
management were gathered at

the Heidenheim engineering
centre to welcome guests
from Australia, Singapore, theUSA and numerous European
countries. “For us the press –and above all the paper industry press – is a very importantpartner”, said Müller. “As far
as technical advances andcustomer benefit are con-ing. Out of the red straightafter take-off. Unexpectedly
high order intake”… These
are only some of the headlines appearing after the 1995
VSPT press conference. And
everyone who attended thisfertile round of discussion
wants to come back again
next time.

54

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

Paper and Culture

In eastern Baden-Württemberg, at thecrossroads between Heidenheim and
Nördlingen, Aalen and Dillingen, lies
Neresheim – only a few minutes from the
Würzburg-Ulm motorway.
Whichever way you approach Neresheim,
you will be surprised by an imposing collection of buildings dominating the town
from its 582 m.a.s.l. vantage point – theBenedictine abbey. On a clear day theview from here extends to the Alpine
peaks. This year Neresheim Abbey cele-

55

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

residence in Neresheim Abbey. Toward
the end of the Thirty Years’ War theabbey became headquarters of the Swedish General Lorenz von Hofkirch.

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

The same fate befell the abbey during the
Coalition Wars of 1796 to 1801, when
General Moreau set up headquarters for
Napoleon’s troops in Neresheim. As if forthe sake of posterity, he nonchalantly
recorded his daily log in the abbey libraryguest-book.

56

Most important baroque church
north of the Alps
When Balthasar Neumann, born in 1687
of an Eger clothmaker, was approachedby Abbot Aurelius of Neresheim, he wasalready reputed to be the greatest architect between Cologne and Constance. His
creative intuition was combined with anenormous capacity for hard work and agenial talent for organization. In his position as senior architect to the Archbishop
of Würzburg, he was responsible for construction works throughout the land as
well as for the building materials andglass manufacturing plants which hehimself had founded. As artillery colonel
he was responsible for military defence
and engineering, artillery and fortifications. And as engineer he held an important teaching post in civil and military
construction. At times Neumann was incharge of more than 10,000 workers distributed among his various building sites.
With no telephone communications or
copying facilities and only horse transport, this seems an impossible task today– but as we can see, it was indeed possible.

Two dozen incunabula still remaining
Despite 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 Germany whose form and content hasremained more or less intact over the
centuries. As a highlight among almost
twenty thousand volumes ranging fromthe fifteenth to early nineteenth centuries
25 incunabula have been preserved here.
The relatively extensive collection as it
stands today was built up throughsystematic acquisition and exchange, or
thanks to foundations and donations. A
number of works were acquired as a kindof “morning gift” from the mother house
Beuron and other monasteries when theabbey was newly founded. Prince Albertof Thurn and Taxis and his consort Margaretha of Austria bequeathed the new
abbey 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 from
more 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 restructuring measures. Interior restoration work is
still underway, with particular outlay
required for the library room with its valuable stucco ceilings. Thanks to generous support from local firms, the BadenWürttemberg authorities and international well-wishers, it is hoped to reopen thelibrary in one or two years as a European
centre of learning.

The library is not the only attraction,
however. Neresheim Abbey is well worth
visiting as one of Europe’s most interesting and best-preserved baroque edifices.
Construction of the present buildings
started in 1694 and took thirty years tocomplete, interrupted by wars and lack offunds.
The crowning glory is the abbey church
designed by Germany’s most famous
architect of the day, Balthasar Neumann
of Würzburg who was also an artillerycolonel.

Neresheim represents the peak of
Neumann’s achievements in ecclesiasticalarchitecture. At the height of his creative
powers and in his best years, he incorporated in this building all the ideas inspiring his most important work. It is herethat Balthasar Neumann expressed his
sense of grandiose celebrity with thegreatest perfection. The masterpiece of
baroque architecture we are privileged tosee and admire in Neresheim today is atrue statement of timeless nobility.

Paper and Culture57