BL0055-000

Bleach Stage Washers, Pumps and Mixers; Bleach Stage Washers, Pumps and Mixers; Putting the Components TogetherPutting the Components TogetherBill Miller, MCBill Miller, MC®® Product ManagerProduct ManagerSulzer Process Pumps (US) Inc.Sulzer Process Pumps (US) Inc.Easley,SCEasley,SC

Bleach Stage Components Bleach Stage Components

Retentiontime

Washer Pump Mixer Tower

Bleach Stage Feed System:Bleach Stage Feed System:Three Essential Components to Work as One Three Essential Components to Work as One

Retentiontime

Washer Pump Mixer Tower

ConsistencySteam usageWater usage

Chemical usageBrightness

ConsistencySteam usage

Even feedSystem pressure

BrightnessConsistency

Chemical usageBrightness

Uniform consistencyEven flow

Accurate process control

WashersWashersOperationOperationDesignDesignPerformance Performance

Bleach Plant Washer Bleach Plant Washer

PurposePurposeReduce carryover levels to bleach stage (organic and inorganic)Reduce carryover levels to bleach stage (organic and inorganic)Adjust pH and temperature of pulpAdjust pH and temperature of pulpThicken pulpThicken pulp

Method (with filtrate recycle)Method (with filtrate recycle)Use cleaner filtrates or warm fresh water on lower showers (washUse cleaner filtrates or warm fresh water on lower showers (wash))Use filtrates from following bleach stage on upper showers Use filtrates from following bleach stage on upper showers (pH and temperature)(pH and temperature)

BL0055-031

Bleach Plant Washers in North AmericaBleach Plant Washers in North America

Operate above design specific loadingOperate above design specific loadingOlder, original part of pulp mill operationOlder, original part of pulp mill operationPrimarily drum washers (vacuum and pressure)Primarily drum washers (vacuum and pressure)

reference 1BL0055-003

Vacuum Pressure Nip Pressure

Displacement Ratio and Mat MechanicsDisplacement Ratio and Mat MechanicsPrinciples of Washing TheoryPrinciples of Washing Theory

Subscripts:Subscripts:

V V –– Inlet (vat)Inlet (vat)

S S –– ShowerShower

D D –– Discharge (mat)Discharge (mat)

Displacement ratio = DR =Displacement ratio = DR =

Wash ratio = RW= LWash ratio = RW= Lss/L/LDD

SSVV -- SSDD

SSVV -- SSSS

S =S = Concentration ofConcentration ofdissolved solidsdissolved solids

L =L = Weight unit of filtrateWeight unit of filtrate

Pulp mat Drum

SV

SD

SS

LLSS = kg shower/kg pulp= kg shower/kg pulp

LLDD = kg in pulp/kg pulp= kg in pulp/kg pulp

Reference 2 & 3BL0055-041

CD0001-005C

Drum Washing StepsDrum Washing Steps

DilutionDilutionExtractionExtractionDisplacementDisplacementExtractionExtraction

reference 2BL0055-007

Drum Washing StepsDrum Washing Steps

DilutionDilutionExtractionExtractionDisplDisplacaceementmentExtractionExtraction

Lower ShowerLower Shower-- WasWashUpper ShowerUpper Shower--Medium ExchangeMedium Exchange

BL0055-046

Bleach Plant WashingBleach Plant Washing

Washer Location

Washing Goal

Wash Filtrates Utilized

D0 Stage

Acids, organics, inorganics (Ca, Mn, etc.), pH,

temperature

D stage, fresh water condensate, Eop stage

Eop Stage

Alkali, organics, pH,

temperature

D stage, fresh water,

condensate,

D Stage

Conductivity, chlorides, ‘”anionic trash”

Fresh water, condensate

Vacuum Drum DesignsVacuum Drum Designs

Center Drainage -Flat Valve - Drive Shaft

End Drainage -Radial Valve - Drive Trunnion

End Drainage Vacuum Filter (GL&V)End Drainage Vacuum Filter (GL&V)Radial Valve, Trunnion DriveRadial Valve, Trunnion Drive

VALVEDRAINAGE BUCKET

CORRUGATED DECK

INLET BOX

DROPLEG

DISPLACEMENT SHOWER

FACE WIRE

DRUM ROTATION

TAKE-OFF ASSEMBLY

REPULPER

BL0055-010CD0022-002

Worm Gear DriveWORM GEAR DRIVEWORM GEAR DRIVEWORM GEAR DRIVE

Face Wire SupportFace Wire Support

CYLINDER ROTATION

FACE WIRE

WINDINGWIRE

INTERMEDIATE GRID WITH CROSS DRAIN OPENINGS

DIVISION GRID

CYLINDERSHELL

Traditional Wire Wound Anti-Rewet Corrugated Deck

CYLINDER ROTATION

FACE WIRE

REPLACEABLE CORRUGATED DECK

INTERMEDIATE GRID WITH CROSS DRAIN OPENINGS

DIVISION GRID

CYLINDER SHELL

Bleach Washer Seal Tank/Dropleg DesignBleach Washer Seal Tank/Dropleg Design

Recommended ht. > 30 ft.

PulpFeed

To Showeror Effluent

Dropleg

Seal Chamber

BaffleVat

Dilution

FiltrateTank

DrumWasher

Vent

Dropleg Design:Sized for 12 to 16 fps superficial velocityStraight, vertical, drop, no jogs

BL0055-016

Increase Feed ConsistencyIncrease Feed Consistency

Dilution flow/pumping Dilution flow/pumping requirementrequirementExtraction requirementExtraction requirementFiltrate volumeFiltrate volumeSeal tank sizeSeal tank size

reference 2BL0055-007

From 1% to 4% From 1% to 4% reducesreduces

Requires Inlet Box Design

Comparison of Specific Loading RatesComparison of Specific Loading Rates

SWDSWD HWDHWD

Vacuum washer 0.75Vacuum washer 0.75--0.800.80 0.650.65--0.700.70

Pressure washer Pressure washer 2.52.5--2.72.7 2.32.3--2.52.5

Wash Press Wash Press 2.42.4--2.62.6 2.22.2--2.42.4

For various drum washer designs, For various drum washer designs, units in ODTPD/ ftunits in ODTPD/ ft22

WA0027-009

Specific loading = ODTPD/(drum dia. x π)(drum length)

Compaction Baffle (GL&V)Compaction Baffle (GL&V)

BL0055-021CB0051-002

INLET BOX

DISPLACEMENT SHOWER

DRUM ROTATION

TAKE-OFF ASSEMBLY

REPULPER

EXTRACTION

PRESSURIZED AIR

End drainage, corrugated deck, deck plateEnd drainage, corrugated deck, deck plate

Drum Displacer (Drum Displacer (AndritzAndritz))

w a s h l iq u id 1 w a sh l iq u id 1

w a sh l iq u id 2washfiltrate 1

washf iltrate 2

r e t u r n fi lt r a te

e x t r a ct e d fil t r a t ex - f il t r a t e

va cu um f ilt r a t e

Displacement Press DP (Displacement Press DP (MetsoMetso))Hood Shredder

Conveyor

PulpOutlet

PulpInlet

ShowerPipes

VatPressRoll

WashWaterIn Filtrate

Outlet BL0055-022

Bleach Stage Components with Wash PressBleach Stage Components with Wash Press

Wash press/conveyorPump Mixer Tower

Pulp

Filtrate32% cs

12% cs

Drum Utilization for Various Washer DesignsDrum Utilization for Various Washer Designs

BL0055-003

Pressure Nip PressureVacuum

4% feed 4% and 10% feed

Formation ExtractionDisplacementFinal Extraction

Low Level ECF FiberlineLow Level ECF Fiberline

BL0055-027CB0047-001

ODODooEEopopD Sequence D Sequence

Effect of EEffect of EOO Washing on D Stage Brightness Washing on D Stage Brightness DevelopmentDevelopment

455055606570758085

0 0.2 0.4 0.6 0.8 1

ClO2 consumed in D stage, % on pulp

Brig

htne

ss, %

ISO

100%

83% (EO) washer efficiency(CD)(EO) bleached,2.7 kappa numbersoftwood kraft pulp

Reference 4

Bleach Washing MeasurementsBleach Washing MeasurementsD0 washer

Displacement Ratio: Cl-, Ca++, TDS, cond., Eop stage: pH , chemical demandDischarge consistency

EOP washerDisplacement Ratio: COD, TOC, cond., Na+

D stage: pH and pH control, chemical demandDischarge consistency

D washerDisplacement Ratio: Cl-, cond.,Stock prep. chemicalsDischarge consistency BL0055-043

Solids for Washing MeasurementSolids for Washing Measurement

SolubleSolubleEasy to measureEasy to measureRelevant to processRelevant to process

BL0055-043

Penalty for Poor Bleach Plant Washer PerformancePenalty for Poor Bleach Plant Washer Performance

Higher extracted kappa number and lower final brightnessIncreased chemical usage

ClO2

Hydrogen peroxide (Eop)NaOHH2SO4

Scale and/or pitch deposition

BL0055-034

Medium Consistency PumpsMedium Consistency Pumps

Medium Consistency Pumps PurposeMedium Consistency Pumps Purpose

Deliver nonDeliver non--pulsing, stable pulp flowpulsing, stable pulp flowRemove airRemove airReduce mixer loadReduce mixer loadImprove bleach chemical controlImprove bleach chemical control

Bleach Stage

Positive Displacement PumpsPositive Displacement Pumps

No pulp fluidizationNo air removalUneven pulp flow dueto lack of feed controlNo speed control, beltdriveVibration Low head requirementsat higher stockconsistency due to air content, no CV

What goes inis what comes

out

Positive Displacement PumpsPositive Displacement Pumps

Screw feeders

Closed pocket rotors

Belt drive

0902.cdr

FluidizationFluidization

0903.cdr

Air Content in StockAir Content in Stock

Five Functional Zones of Medium Five Functional Zones of Medium Consistency PumpingConsistency Pumping

A. Fluidization Zone, fiber network disrupted by high shear forces.

B. Gas Separation Zone, air is separated from the stock.

C. Pumping Zone, impeller vanes pump stock towards discharge

D. Fiber Return Zone, fibers entrained with air from zone B are returned to the pump discharge.

E. Degassing Zone, air is removed to the degassing unit.

Medium Consistency PumpMedium Consistency Pump

0035.cdr

Medium Consistency Pump Control SystemMedium Consistency Pump Control System

Medium Consistency Pumping Medium Consistency Pumping -- VariablesVariables• Raising consistency from 10% to 12% increases

friction loss by 53%.

• Increasing production from 1000 to 1500 ADST/D increases friction loss by only 6%.

• Raising pH from 7 to 10 decreases friction loss by 43%.

• Dropping temperature from 200°F to 100°F doubles the friction loss.

0904.cdr

Questions?Questions?

MixersMixersDesignDesignOperationOperationPerformance Performance

Mixer PurposeMixer Purpose

Reduce degree of non uniformity in chemical/pulp distribution. Reduce degree of non uniformity in chemical/pulp distribution. Assure each fiber sees equal chemical concentration.Assure each fiber sees equal chemical concentration.Reduce non uniformity by:Reduce non uniformity by:

larger mixer retention timelarger mixer retention timechemical prechemical pre--distributiondistributionproper metering of flowsproper metering of flowseliminate stock flow pulsationeliminate stock flow pulsationmaintain uniform consistency and pressuremaintain uniform consistency and pressure

Three Basic Steps for Mixer Load Three Basic Steps for Mixer Load OptimizationOptimization

PrePre--distributiondistributionbulk flowbulk flowmacromacro--mixing, >10 mm scalemixing, >10 mm scale

Fiber mixing Fiber mixing turbulent shear, diffusionturbulent shear, diffusion0.50.5--10 mm scale10 mm scale

MicroMicro--mixing mixing Diffusion, small scale fluid motionDiffusion, small scale fluid motion<0.05 mm scale<0.05 mm scale

Chemical Addition ConfigurationChemical Addition Configuration

HighHigh--Shear/HighShear/High--Intensity MixersIntensity Mixers

Viewed from Motor

Mixer and Liquid Chemical AdditionMixer and Liquid Chemical Addition

ClO2

Pulp

Mixer

Pulp and

ClO2

ClO2 Mixer Variance Testing

Pre-distribution

FiberMixing

Micro-Mixing

Mixer

2308ppt

Chemical Mixer Chemical Mixer -- Average Flow FieldAverage Flow Field

Mixing Index (M) MeasurementsMixing Index (M) Measurements

M = s/xM = s/x

SS is standard deviation of measured quantityis standard deviation of measured quantityX X is mean value of measured quantityis mean value of measured quantitypipe surface temperature measurementspipe surface temperature measurementsalso determines equivalent chemical chargesalso determines equivalent chemical charges

Mixing indexMixing index has same definition as has same definition as inhomogeneity inhomogeneity or varianceor variance

Liquid mixing only

MixingMixing InhomogeneityInhomogeneity TestingTestingPortable recorderPortable recorderEight (8) surface thermocouplesEight (8) surface thermocouples

InsulatedInsulatedCalibratedCalibrated

Eight (8) temperature data sets after ClOEight (8) temperature data sets after ClO22Thirty (30) minute intervalsThirty (30) minute intervals

One (1) stock temperature reading before ClOOne (1) stock temperature reading before ClO22

One (1) ClOOne (1) ClO22 temperaturetemperature

ClO2

Pulp

Mixer

Pulp and

ClO2

ClO2 Mixer Variance Testing

MixerT1

T2

T3

T4T5

T6

T7

T8

TSTC

Balance CalculationsBalance Calculations

InhomogeneityInhomogeneity CalculationsCalculations

Importance of ClOImportance of ClO22 Line Configuration Line Configuration Optimized for PreOptimized for Pre--Distribution Addition Distribution Addition

0

5

10

15

20

25

before before before before after after after

inhomog,%#ClO2/T(act)

ConclusionConclusionBleach Stage Feed System ComponentsBleach Stage Feed System Components

Pulp consistencyPulp consistencyProcess flow stabilityProcess flow stabilityProcess control accuracyProcess control accuracyBleach chemical usageBleach chemical usageBrightness ceilingBrightness ceiling

Will impactWill impact

BL0055-049