bleach stage washers, pumps and mixers; putting the ...pplant.uga.edu/tappi/washing pumping...
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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