Paper Machine

Paper machine
1 | Papiermachine | Sappi Fine Paper Europe

Contents

1. The history of paper 3

2. The paper machine – Parts & components 8
2.1. Schematic overview 10
2.2. Wet end 12
2.3. Head box 14
2.4. Wire section 17
2.4.1. Couch broke 20
2.5. Press section 21
2.5.1. Conventional & German presses 22
2.5.2. Shoe press 23
2.6. Drying section 24
2.7. Size press 27
2.7.1. Conventional size presses 28
2.7.2. Film press 29
2.7.3. IR drying 30
2.8. Calender 31
2.9. Winder 32

3. Water circulation 34

1. The history of paper

• China: earliest paper remains
– 180-50 B.C.
– Paper from the early Han dynasty has been found in various parts of China,
proving that paper was used at this early stage.

• Invention of paper and spread from China
– 105 B.C.
– Tsai Lun from Gue Yang in the province of Hunan reports his invention of
paper to the Chinese emperor Ho Ti. The materials he used for his paper
were tree bark, hemp, rags and fishing nets (Häberli).



• 610
– Introduction of paper making in Japan

• 751
– The Arabs learn the art of paper making from Chinese
prisoners of war

• 794
– Various paper mills are built in Bagdad

• 1109
– Earliest paper document (Archive of Palermo, Italy)

• 1144
– First mention of a paper mill in Spain (Xativa/San
Felipe near Valencia)



• 1390/91
– First German paper mill built in Nürnberg by
Ulman Stromer

• 1436 - 1444
– Gutenberg performs various printing
experiments in Strasbourg

• 1450
– Gutenberg signs a contract with Mainz citizen
Fust for the production of a printed bible

• 1472
– A paper mill is built on the Wert Place in
Zürich

• 1490
– First paper mill in England



• 1706
– First paper mill is built in Alfeld

• 1774
– Discovery of chloride as a bleaching agent

• 1798
– France: Invention of the continuous wire paper machine by Nicolas-Louis Robert

• 1799
– The continuous wire paper machine is patented



• 1803 – 1806
– Didot and his English brother-in-law John Gamble acquire a patent in England and sell
their rights to London based paper merchants Henry and Sealy Fourdrinier
– First paper machines built by English machine manufacturer Hall in Dartford, Kent,
under general direction of Bryan Donkin

• 1841
– Paper machine construction by Escher Wyss in Switzerland

• 1872
– Sulphite process

• 1884
– Sulphate process


2. The paper machine – Parts & components

• Components
– Wet end
– Headbox
– Wire section
– Press section
– Drying section
– Size press
– Winder

• Paper machine must be adapted to specific paper and its intended use
– Paper machine for fine papers
– Yankee paper machine for special papers
– Tissue paper machine


2.1. Paper machine - Construction


2.1. Schematic overview

Headbox Drying sections 1 & 2 Jumbo reel
99% water

Wire section Press section
Size press Calender

Wet end


2.2. Wet end

• All components from stock preparation to headbox
– Supply bins
– Cleaner (cone spinner  centrifugal force)
– Pressure screen
– Re-grinding refiner
– Conduits

• Purpose:
– Bridge between stock preparation and headbox
– Transport of paper stock from stock preparation to paper machine
– Stock density: 1% solid material, 99% water
– Stock has to be absolutely clean


2.2. Wet end

Cleaner – Cone spinner Pressure screen


2.3. Headbox

• Purpose:
– Even stock distribution on the wire
– Uniform basis weight across the entire width
– Crushing all structures in the stock
– Sheet formation on the wire instead of in or before the headbox


2.3. Headbox


2.3. Headbox

High pressure headbox

High turbulence headbox


2.4. Wire section

• Purpose:
– De-watering of the paper web, allowing it to be taken over by the press
section
– Sheet formation / sheet structuring

• Process:
– The mixture of water and cellulose is sprayed onto one or between two wires
 1% cellulose, 99% water
 PVC wire, formerly bronze
– Two wires:
 Water simultaneously drains off in both directions (above and beneath)
 No side differences, no wire and felt side
 De-watering by vacuum and as a result of surface tension


2.4. Wire section
Classical Fourdrinier paper machine

1. Forming board
2. Register rolls
3. Wet suction boxes
4. Single foils
5. Suction boxes
6. Breast roll
7. Wire suction roll
8. Wire drive roll
9. Egoutteur*

*Egoutteur: wire roll used to smooth the paper web and enhance density. Can also be used
for watermarking.


2.4. Wire section
Example of double wire


2.4.1. Couch broke

Pick-up roll

Couch broke = paper web edges sprayed off by the side
jets or, in case of a web break, the entire web.
Waste bin


2.5. Press section

• Purpose:
– Mechanical de-watering of the moist fibre suspension

• Process:
– The paper web is supported by two felt rolls pressing the paper
– The last roll is commonly known as the „German press“ without felt
– Press nips increase the proportion of dry material to approx. 55%
 At maximum press nip the dry material proportion can be as high as 70%
 Followed by re-moistening by capillar interaction between felt and paper web

Press felts

Paper web


2.5.1. Konventional & German press

Felt

Conventional
press
German
press

Conventional press: 2 rolls – 1 nip – 1 felt
German press: 2 rolls – 1 nip – no felt


2.5.2. Shoe press

• Current technical status
– Sphere instead of nip

Upper roll

Shoe

Press felt

Lower roll

– Drying is more economical and faster
– Drawback: more technical effort and expensive equipment


2.6. Drying section

• Purpose:
– Bringing the paper web to the desired degree of final dryness by leading it
over a series of vapour heated rolls
 Higher degree of moisture in sheets (approx. 55%) than in reel paper (approx. 30%)

• Process:
– The paper web is transported between a series of vapour heated cilinders
and felts
– The felts also ensure fixation
– Thermal drying
 Starting temperature: approx. 60°C
 Final temperature: approx. 118°C
 Gradual drying  to prevent picking
– The drying section is the most energy intensive part of the paper machine
 Combined power/heat installations are often used
 Residual heat, such as exhaust steam, is often used


2.6. Drying section


2.6. Drying section

Heated steel
Fixing felts
rolls


2.7. Size press

• Purpose:
– Making the paper web surface water repellent
– Size and film press (in some cases off-line)
– Paper must be ink retaining, or, in other words, water repellent
– Ink has to stay on the paper surface
 On the paper, not in the paper
 Measuring unit: Cobb value

– Different types of sizing can be used – bulk sizing, surface sizing
and mixed methods


2.7.1. Conventional size press

Roll

Size pool


2.7.2. Film press

Sizing nip
Sized
paper web

Unsized
paper web
Roll blade Sizing jets


2.7.3. IR drying
Infrared

• IR drying usually takes place after sizing, behind the size press
– In support of drying section 2
– Shock drying, gas radiation
– Temperature: approx. 1000°C


2.8. Calender
Soft calendering

Rubber roll

Paper web

Heated
steel roll


2.9. Winder

• Weight: 20 to 200 tons
• „Flying Splice“ = Roll change „on the fly“
Core
Empty core
magazine

Fully wound
mother reel


2.9. Winder


3. Water circulation


Thank you
for your attention

Jörg Abelmann


Paper Machine

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