WOOD 120

Pulp and Paper

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Raw material Paper products

Chemical pulp mill

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Chemical pulp mill

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http://www.metsopaper.com/paper/MPwGeneral.nsf/WebWID/WTB-061228-2256F-E7612/$File/Total_scope_with_large_text.jpg

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Surface Section through paper sheet

Composition of Paper

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 Pulp Production (2012)(x106 metric tonnes)

• Recovered paper 212.8

• Mechanical pulp 28.9

• Full chemical pulp 98.1Kraft 94.7Sulphite 3.4

• Dissolving pulp 4.9

• Non-wood fiber pulp 16.1

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http://www.unitedeagle.cn/upimages/20083311435587662.jpg

http://www.partonlumber.com/images/000_0334.jpg

Raw material – wood supplyLogs Chips

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http://www.energysolutionscenter.org/gasirpaper/Images/PaperManfLine.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

wood fibers or fiber bundles

Mechanical pulping

Mechanical Pulping

• Stone ground wood

• Refiner pulps

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Debarking

Drum debarkers

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Stone Ground Wood

grinding stone

bolts of wood

hydraulic pistons

pulp slurry

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Stone Ground Wood

Stone Ground Wood

• 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

Pretreatment of chips

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http://www.triple-r.co.nz/pop/pop_pulp09.html

http://www.globalequip.com/photos/bg_901371.001_2.jpg

Refiner pulping

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http://www.metsopaper.com/paper/MPwFiber.nsf/WebWID/WTB-041123-2256F-3E65B/$File/TMP_blue222.jpg

Multiple refiners in parallel

Refiner pulping

• 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”

• RMPrefiner 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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wood individual fibers

Chemical pulping

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 solubilityTolerates wide range of speciesHigh strength pulpLower yield than mechanical pulps

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Kraft digester - continuous

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http://www.outokumpu.com/35127.epibrw 

http://us.magnetrol.com/Images/Applications/PulpDigester.jpg

Kraft pulping – continuous digester

1. Chips and pulping chemicals

2. Steam

3. Blow valve

4. Gases

5. Pulp

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Pulping

Evaporation

Burning

Washing

Cauticising

Whiteliquor

Wood

PulpBleaching

Bailing &Shipping

Kraft liquor recovery cycle

Greenliquor

Blackliquor

Green liquor recovery cycle

Pulp treatment

• Bleaching / Brightening

• Beating (refining)

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http://www.energysolutionscenter.org/gasirpaper/Images/PaperManfLine.jpg

Pulp and Paper – overview of production stages

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http://www.chmltech.com/pulppaper_files/pulp%20bleaching.jpg

Raw material Paper products

Bleaching vs. Brightening

Bleaching• Continuation of

pulping process• Removal of residual

lignin left after pulping• 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

• C chlorine Cl2• D chlorine dioxide ClO2

• O oxygen O2

• Z ozone O3

• P peroxide H2O2

• E alkaline extraction 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

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http://www.andritz.com/cir-pic-pk-ar-2002.jpg

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

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Jordan refiner

Pulp Beating

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Before beating After beating

Internal and external defibrillation take place

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

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http://www.risiinfo.com/images/magazine/pp_mag/1102papermaking21A.jpg

Foudrinier - schematic

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http://www.astenjohnson.com/images/images_paper-machine.jpg

Blending of pulp stocks

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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

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Schematic of cylinder machine

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Screen rotates

Mold remains fixed

Paper layer forms on screen

Level of pulp stock

Couch roll

vacuum pressure

Fibres in suspension

Cylinder papermaking machine

Dryers

World Paper Production (2012)(x106 metric tonnes)

• Wrapping, packaging 214.4 and board

• Coated paper 42.4

• Newsprint 30.1

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