WOOD 120
Pulp and Paper
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Raw material
Paper products
Chemical pulp mill
http://w3.upm-kymmene.com/upm/internet/cms/upmmma.nsf/lupGraphics/Botnia_Fray%20Bentos%20mill_1.jpg/$file/Botnia_Fray%20Bentos%20mill_1.jpg
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Chemical pulp mill
http://www.metsopaper.com/paper/MPwGeneral.nsf/WebWID/WTB-061228-2256F-E7612/$File/Total_scope_with_large_text.jpg
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Composition of Paper
Surface
Section through paper sheet
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Lignin “glues”
wood cells
together
wood
fibers or fiber bundles
Pulping
Mechanical
• Uses heat and
mechanical energy
• Higher yield
• Lower quality
Chemical
• Uses heat and
chemical energy
• Lower yield
• Higher quality
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World Production (2002)
(x106 metric tonnes)
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Recovered paper
Mechanical pulp
Semi-chemical pulp
Full chemical pulp
Kraft
116.5
Sulphite
5.3
• Dissolving pulp
• Non-wood fiber pulp
140.7
34.7
8.4
121.8
2.8
19.8
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Raw material – wood supply
Logs
Chips
http://www.partonlumber.com/images/000_0334.jpg
www.panoramio.com/photos/original/3042908.jpg
http://www.unitedeagle.cn/upimages/20083311435587662.jpg
Pulp and Paper – overview of production stages
http://www.energysolutionscenter.org/gasirpaper/Images/PaperManfLine.jpg
Pulping
http://www.energysolutionscenter.org/gasirpaper/Images/PaperManfLine.jpg
Pulp treatment
http://www.energysolutionscenter.org/gasirpaper/Images/PaperManfLine.jpg
Papermaking
http://www.energysolutionscenter.org/gasirpaper/Images/PaperManfLine.jpg
Mechanical pulping
wood
fibers or fiber bundles
Mechanical Pulping
• Stone ground wood
• Refiner pulps
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Debarking
Drum debarkers
Stone Ground Wood
bolts of wood
hydraulic pistons
grinding stone
pulp slurry
http://chempatec-auhorn.com/images/pressurizedmechanicalpulpproduction001_480.jpg
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Stone Ground Wood
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Stone Ground Wood
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Raw material – short logs (bolts)
High yield
Low quality fibers or fiber bundles
High energy input
Pulp suitable for tissues
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Refiner pulping
http://www.tut.fi/optics/aoresearch/dlstrobo/
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Pretreatment of chips
Disc refiner detail
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Refiner pulping
http://www.globalequip.com/photos/bg_901371.001_2.jpg
http://www.triple-r.co.nz/pop/pop_pulp09.html
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Multiple refiners in parallel
http://www.metsopaper.com/paper/MPwFiber.nsf/WebWID/WTB-041123-2256F-3E65B/$File/TMP_blue222.jpg
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Refiner pulping
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Raw material – chips
Lower yield than SGW
Medium quality fibers or fiber bundles
High energy input
Pulp suitable for newsprint
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The “Alphabet Pulps”
• RMP refiner mechanical pulp
• TMP
thermo mechanical pulp
• CTMP chemi thermo mechancial pulp
• SGW stone ground wood
• PGW pressurized ground wood
• NSSC neutral sulfite semi chemical
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Chemical pulping
wood
individual fibers
Chemical Pulping
•Sulfate process (Kraft)
•Sulfite process
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Kraft process
Delignifies wood by
• fragmenting lignin into smaller units
• adding chemical groups to increase
the lignin’s solubility
Tolerates wide range of species
High strength pulp
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Kraft digester - continuous
http://us.magnetrol.com/Images/Applications/PulpDigester.jpg
http://www.outokumpu.com/35127.epibrw
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Kraft pulping – continuous digester
1.
2.
3.
4.
5.
Chips and pulping chemicals
Steam
Blow valve
Gases
Pulp
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Kraft liquor recovery cycle
Wood
Pulping
Pulp
White
liquor
Washing
Evaporation
Cauticising
Green
liquor
Burning
Black
liquor
Bleaching
Bailing &
Shipping
Pulp treatment
• Bleaching / Brightening
• Beating (refining)
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http://www.chmltech.com/pulppaper_files/pulp%20bleaching.jpg
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Raw material
Paper products
Bleaching vs. Brightening
Bleaching
• Continuation of
pulping process
• Removal of residual
lignin
• More permanent
• Applied to chemical
pulps
Brightening
• Distinct from pulping
process
• Impact chromophoric
structures in lignin
• More temporary
• Applied to mechanical
pulps
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Bleaching/brightening chemicals
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C
D
O
Z
P
E
chlorine
chlorine dioxide
oxygen
ozone
peroxide
alkaline extraction
Cl2
ClO2
O2
O3
H 2O 2
NaOH
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Bleaching/brightening sequences
• Classic
e.g., C E D E D
• Elemental Chlorine Free (ECF)
e.g., D E D E D
• Totally Chlorine Free (TCF)
e.g., O Z E P
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Bleaching Towers
http://www.andritz.com/cir-pic-pk-ar-2002.jpg
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Pulp Beating
• Flattens fibers to produce larger surface
area – increases hydrogen bonding
between fibers
• Unravels fibers to some degree
• Optimum beating time to achieve best
paper properties
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Pulp Beating
Jordan refiner
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Pulp Beating
Before beating
After beating
Internal and external defibrillation take place
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Papermaking
Foudrinier machine
- thinner paper sheet
- faster production speed
Cylinder machine
- thicker paper sheet
- slower production speed
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Papermaking
• Foudrinier machine
- thinner paper sheet
- faster production speed
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Foudrinier papermaking machine
http://www.risiinfo.com/images/magazine/pp_mag/1102papermaking21A.jpg
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Foudrinier - schematic
http://www.astenjohnson.com/images/images_paper-machine.jpg
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Blending of pulp stocks
http://www.dkimages.com/discover/previews/767/108027.JPG
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Foudrinier papermaking machine
Foudrinier – wet-end
Foudrinier - presses
Foudrinier – dry-end
Foudrinier – calendering and winding
Foudrinier – moisture loss in paper
Papermaking
• Cylinder machine
- thicker paper sheet
- slower production speed
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Cylinder papermaking machine
Cylinder papermaking machine
http://www.zangyeu.com.tw/2007/003.jpg
Schematic of cylinder machine
Couch roll
Paper layer forms on screen
Level of pulp stock
vacuum
pressure
Fibres in suspension
Screen rotates
Mold remains fixed
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Cylinder papermaking machine
Dryers