Paper technology program for Taiwan TAPPI

CG Kiang2010 04 27 Taichung, Taiwan

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Paper mill

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Paper machine in the stone age

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: 0.2-1.5% : ;2% : 20% : 60%-50% : 40%-50%90%-95% 2010 04/CGK 5

Paper machine in 1884

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Paper machine in 2000s

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Paper machine in 2000sDry End

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20% 40-50%

90%-95%

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Paper machineSections

Formation section

Press section

Dryer section Head box

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Paper machineDewatering wet end

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Couching cons. 8-10%

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Headbox cons. 0.30-0.50%

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Headbox cons. 0.50-0.70%rm Fo00

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Couching cons. 8-10% Couching cons. 8-10%uc n tio x bo sf

ox rb e Fl s at uc

an x oxtr bo bet ne l er F io h sf ct S an su tr t at ee Fl Sh s at

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Dryness 24-26%

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Paper machineDewatering - press

up to 50 % consistency ~ 34-36% consistency ~ 38-40% consistency ~ 20-25% consistency ~ 30% consistency

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Paper machineDrying~ 50 % consistency 8 12% moisture content

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Paper machineMain types The following main types of paper machines are significant today :- Fourdrinier machines - Combination machines - In vat machines ( cylinder machine ) - Tissue paper machines - Board machines - Twinwire machines2010 04/CGK 14

( Fourdriner Machine )

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Paper machineFourdrinier machine development

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Paper machineCombination machine folding boxboard machine

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( Combination Machine )

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Paper machineMG dryer Yankee dryer

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Paper machineMG dryer Yankee dryer

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Paper machineMG dryer Yankee dryer Purposes of useWrapping paper machines MG-gloss as a target for the sake of appearance Usually combined machines owing to capacity Multi-layer board machines The Yankee dryer is used not only to gain gloss, but also to gain smoothness without losing bulk (stiffness). It is difficult to perform a sufficient amount of drying using the Yankee dryer Crpe paper machines MG-gloss is not set as a target. The Yankee cylinder drying efficiency may become a bottleneck for the production2010 04/CGK 21

Paper machineMG dryer Yankee dryerEffect of the MG cylinder drying on board surface

Surface prior to MG cylinder2010 04/CGK 22

Surface after MG cylinder

In vat cylinder machine direct flowVACUUM BOXES

COUCH ROLL

SHOWER TO DRIERS

COUCH ROLL PRESS ROLLS WHITE WATER DISCHARGED THROUGH CENTER

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In vat cylinder machine contra flowVACUUM BOXES COUCH ROLL

SHOWER

TO DRIERS

COUCH ROLL PRESS ROLLS WHITE WATER DISCHARGED THROUGH CENTER

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In vat cylinder machineMulti-layer board machine

Couch rollShower water

Suction box

Forming cylinder

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( Tissue Paper Machine )

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( Board Machine )

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( Twinwire Machine )

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Paper machineTwinwire machine

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Paper machineBoard machine

Fourdrinier and secondary gap forming unit

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Paper machineBoard machine

Primary gap forming unit and on-top fourdrinier

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Paper machineBoard machine

2-Ply gap forming section

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Raw materials and their effect on final product Recycled fiber Less bulky Lower brightness Lower tensile High fines content => slow drainage

Virgin fiber bulky and high brightness good tensile fast drainage

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Three-, Four- or Five ply forming section3-layer forming Scandinavian type Folding box board

4-layer forming high quality WLC

5-layer forming high quality and versatile concept

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Linerboard structure Top ply: Undertop ply: Back ply: UKP, OCC OCC, Mixed waste, Broke OCC

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Two layer headbox producing containerboardEuropean OCC and mixed waste

2-layer forming

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Paper machineHeadbox The headbox has four main functions :1. 2. To spread the stock flow across the entire width of the wire To maintain a turbulence in the stock to prevent formation of fiber flock To remove temporal and spatial flow disturbances that may cause basis weight variations To produce a stock flow of desired consistency, speed and direction to the wire

3.

4.

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Paper machineHeadbox The traditional headbox is formed of the following components :- Inlet header - Headbox with rectifier rolls and air cushion - Slice with top slice and apron

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Paper machineHeadbox

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HeadboxInlet header conic pipesThe shape of the inlet header is to optimized to distribute the stock evenly across the width of the machine, especially uniform distribution for all flow rates not only for headbox design flow rate Electropolished for all flow surfaces is must

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HeadboxInlet header tapered right angle ducts

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HeadboxBox rectifier rolls

Tampella rectifier roll headbox2010 04/CGK 42

HeadboxBox rectifier rollsStock flows in headbox with rotating and stationary rolls

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HeadboxBox rectifier rolls

Accumulation of fibers in a rectifier roll

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HeadboxBox rectifier rolls The rectifier rolls has many disadvantages :1. 2. A great part of the flow passes in between the rectifier rolls and is therefore not mixed Influence of the inlet header on the flow on such a way that vortexes are formed inside and between the rolls. Since these vortexes are not identical across the entire width of the headbox, they cause severe disturbances in the flow The rectifier rolls is the occasional piling of fibers on the surfaces between the holes or on the edges, when flushed away, they end up as hard fiber lumps in the paper Paper quality can be decisively influenced by such factors as the openness of roll, hole size and location of the rectifier roll which located closest by the headbox outlet. As the machine speed increased, it is the roll that usually cause a problem

3. 4.

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HeadboxBox rectifier rolls The rectifier rolls are necessary in every headbox for the following reasons :1. The rectifier rolls even out the flow speed in the cross direction of headbox and stabilize the flow The rectifier rolls evoke turbulence in the entire headbox. It helps disperses fiber lumps so that in the outflowing mixture, the fibers are evenly distributed in the water

2.

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HeadboxBox air cushion On open headbox, the ratio between surface level h ( cm ) and outflowing speed V ( m/min ) : h = V 2 / 700h V

V = 300 m/min ; h = 125 cm

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HeadboxBox air cushion

Valmet air cushion headbox2010 04/CGK 48

HeadboxBox air cushion

Air cushion headbox2010 04/CGK 49

HeadboxBox air cushion

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HeadboxBox air cushion

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HeadboxBox air cushion

Pulsation dampening located close to slice without a compromise Dampens both dilution and main flows Continuous flow from stilling chamber to overflow No back flow or build-ups to main flow

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HeadboxBox air cushion

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HeadboxBox air cushion

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HeadboxBox attenuator

Attenuator which incorporates headbox for dampening of pressure pulsations

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HeadboxBox attenuator dampen pressure pulsation

Prior to headbox

After headbox2010 04/CGK 56

HeadboxSlice

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HeadboxSlice

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HeadboxSlice.4 in .2 in 10 mm 5 mm max 150 mm [6 in]

0.79 in max -2 in min 0 in O of breast roll

20 mm max -50 mm min 0 mm

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HeadboxHigh turbulence headbox

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HeadboxHigh turbulence headbox

Pressure loss to : Create micro turbulence Uniform CD flow distribution (profiles and fiber orientation) Improve pulsation dampening for MD variation control

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HeadboxHigh turbulence headbox

smooth flow geometry from round to rectangular

Low large scale turbulence low random basis weight variation good stability

Turbulence level fine tuning with turbulence sheets

Fluidization in circular enlargement

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HeadboxHigh turbulence headboxm/s f/s

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HeadboxHigh turbulence headbox - multilayer

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HeadboxHigh turbulence headbox - multilayer

Multilayer separation by vanes

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Formation of sheetFlow monitoring in short circulationVariations in the flow speed, consistency or in the properties of the stock temporal or across the headbox - lead to grammage variations, poor sheet formation and many other difficulties. The problems can often be localized in the short circulation or drive unit and may often lead to change of headbox If the fiber form large flocks in the slice section, it is difficult to correct later in the process. If the flow is too turbulent on the other side, it tears the earlier formed sheet off and makes the paper cloudy although the fibers are relatively well distributed2010 04/CGK 66

Formation of sheetFlow monitoring in short circulationOne-sidedness means a difference in the formation, filler content or fiber orientation between the top and bottom sides of paper sheet One-sidedness is determined e.g. by the impingement angle of the stock jet and the wire. The angle is set by shifting the top slice in the horizontal direction.

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Formation of sheetPaper formation measurement by small scale beta absorption

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Formation of sheetFormation analyzer measuring principle

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Formation of sheetFormation - what are variationsCD profile

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Paper sheet is a measure and an image of pressure and flow conditions

MD profile

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Residual variations

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Machine direction

Formation of sheetFormation - typical variations in paperCD

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CD profile depends on performance of profiling actuators of headbox and other sections in PM. (usually 0,3 - 0,6 % from average) MD variations come from variations in raw material and chemical aid supplies, consistency and pressure controls. Fast (20..30 Hz) MD-variations come from pulsation for example piping, fan pump, machine screen. Note: pulsation can appear also at frequency-multipliers (0,1 - 1,5 % from average)

MD

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Unsystematical variations come from incomplete mixing in approach system and from unstable drainage process. (0,6 - 2,5 % from average)

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Paper structure engineering

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( Forming ) : (Fourdriner machine) (Cylinder machine)

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( Fourdriner machine )

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BeloitBel-Bond I. (formation) II. III.

610m/min 150g/m2 45 ton/min/cm

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BeloitBel-Bond

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CEDECOPond

I. II. III. IV. 700 m/min 20-90 g/m2

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Escher Wyss(Top Former)

I.MD/CD2151 II. III. : 400 m/min 25-60 g/m2

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Escher Wyss(Short Top Former)

: 40-750 m/min 25-350 g/m2

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KobayashiUltra

I. II. 500 m/min 40-100g/m2

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KobayashiSuccess

700 m/min 40-100g/m2

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Voith:(Compact Wire Former)

: : 700 m/min 30-220 g/m2

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Voith:(Compact Wire Former)

80-600 m/min 80-400 g/m2

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( Cylinder machine )

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( Cylinder machine )

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( Cylinder machine ):()

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( Cylinder machine )

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Escher Wyss(Pad Former)

I. II.21/51 III. IV.(2%) 150 m/min() 25-110 g/m2

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Tampella

50-350 m/min 20-130 g/m2

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Tampella Arch Former

70-600 m/min

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Voith:

I.MD/CD II.

250-510 m/min 20-110 g/m2

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( Hybrid former )

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( Gap former ) :

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( Gap former )

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( Gap former )

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( Gap former )

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( Gap former )

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( Multi-ply former )

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( Multi-ply former )

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Paper machineWire section drainage

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Headbox cons. 0.30-0.50%

2-3 0 0 0

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Headbox cons. 0.50-0.70%

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Couching Couching cons. 8-10% cons. 8-10%ox rb n fe tio ns x xtra uc t bo bo ts n ee la er F io h sf ct S an su tr t at ee Fl Sh x bo n tio uc s n io ct su x bo x bo

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Dryness 24-26%

at Fl at Fl

KSD/BRD 499338_1 9/93

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Paper machineWire section - drainage

1% 7-8% 4-5% 11 % 32 % 4% 12 % 35 % 1,5 - 2 %10 0 %

2,5 % 15-18 % 0,5 %

2%

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Paper machineTissue machine suction former

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Paper machineTissue machine drycrepe, Crescent former

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Paper machineTissue machine drycrepe, Crescent former

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Paper machineTissue machine drycrepe, Crescent former

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Paper machineTissue machine

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Paper machineTissue paper

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Paper machineTissue paper

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Paper machineTissue paper

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Paper machineTAD tissue machine

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Paper machineTAD tissue machine - elements

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Paper machineTissue machine

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Paper machineTAD tissue machine moulding process

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Paper machineTAD tissue machine roll with through head exhaust

Air flow

Air flow2010 04/CGK 114

Paper machineTAD tissue machine through dryer process

Combustion fan

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