paper machine
DESCRIPTION
TRANSCRIPT
| Papiermachine | Sappi Fine Paper Europe 1
Paper machine
| Papiermachine | Sappi Fine Paper Europe 2
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
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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).
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1. The history of paper
• 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)
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1. The history of paper
• 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
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1. The history of paper
• 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
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1. The history of paper
• 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
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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
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2.1. Paper machine - Construction
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2.1. Schematic overview
Headbox 99% water
Wire section Press section
Size press
Drying sections 1 & 2
Calender
Jumbo reel
Wet end
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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
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2.2. Wet end
Cleaner – Cone spinner Pressure screen
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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
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2.3. Headbox
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2.3. Headbox
High turbulence headbox
High pressure headbox
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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
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2.4. Wire section Classical Fourdrinier paper machine
*Egoutteur: wire roll used to smooth the paper web and enhance density. Can also be used for watermarking.
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*
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2.4. Wire section Example of double wire
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2.4.1. Couch broke
Couch broke = paper web edges sprayed off by the side jets or, in case of a web break, the entire web.
Waste bin
Pick-up roll
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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
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2.5.1. Konventional & German press
Conventional
press
German
press
Felt
Conventional press: 2 rolls – 1 nip – 1 felt
German press: 2 rolls – 1 nip – no felt
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2.5.2. Shoe press
• Current technical status
– Sphere instead of nip
– Drying is more economical and faster
– Drawback: more technical effort and expensive equipment
Upper roll
Shoe
Press felt
Lower roll
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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
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2.6. Drying section
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2.6. Drying section
Heated steel
rolls Fixing felts
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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
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2.7.1. Conventional size press
Roll
Size pool
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2.7.2. Film press
Unsized
paper web Sizing jets
Sizing nip
Roll blade
Sized
paper web
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2.7.3. IR drying
• 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
Infrared
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2.8. Calender Soft calendering
Rubber roll
Heated
steel roll
Paper web
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2.9. Winder
• Weight: 20 to 200 tons
• „Flying Splice“ = Roll change „on the fly“
Core
magazine Empty core
Fully wound
mother reel
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2.9. Winder
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3. Water circulation
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Thank you
for your attention
Jörg Abelmann