valmet white liquor plant technology
TRANSCRIPT
Valmet White Liquor Plant TechnologyWestern Canada BLURBACOctober 29, 2014
John B. Johnson IIProduct Technology Manager
Employment History (1981-present)– Goslin-Birmingham: Division of Envirotech– Goslin :Division of Baker Hughes– Goslin :Division of Green Bay Packaging– Thermo Black Clawson– Kadant (name change only)– Eimco :Division of Baker Hughes– Dorr-Oliver Eimco :Division of GL&V– FLSmidth– Metso – Valmet
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Valmet strengthens its position as a leading supplier to the pulp industry by obtaining a license to FLSmidth Lime Kiln and Recausticizing Technology
Valmet has acquired the lime kiln and recausticizing technology of FLSmidth through an exclusive license to that technology. The acquired technology is affiliated to Valmet’s Pulp, Paper and Power segment, Fiber business line.
The acquisition complement Valmet’s portfolio as a full scope supplier to the pulp industry.
3
Licensing Agreement
Background of Valmet white liquor plant technologies
KvaernerPulping
Metso
Dorr-Oliver
Hedemora
Caustec
Kvaerner
Metso
1993
2006
19971935-79
Valmet
2014Dorr-OliverEimco (GL&V)
F.L. Smidth2007
2013
Baker Hughes
GL&V
Eimco1984
2002
2002
Envirotech
4
Valmet– supplier of complete recovery systems
EVAPS™ evaporation systems
RECOX™ recovery boilers
White liquor plant
5
White liquor plant fundamentals
White liquor plant fundamentals
Cooking Washing &screening
Oxygendelignification
Pulp drying
BalingBleaching
Woodhandling
White liquorpreparation
Evaporation
Air pollution control
Recausticizing
Lime kiln
Steam turbine
Recoveryboiler Bleaching chemical
and oxygen supply
Powerboiler
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White liquor plant fundamentals- main areas
8
Green Liquor Handling
White liquor plant fundamentals-green liquor handling
Dregs consists of:– Unburnt carbon– Lime mud (mainly from lime mud filter)– Other
Pulp mill ”kidney”
Reduced effluent flow in pulp mill → more non-process elements in liquor→ tougher dregs removal requirement
10
Non process elements-solubility
Ca, Mg, Mn, Fe, Ba Al
Ca, Mg, Mn, Fe, Ba (Al)
(Al)K, Cl
(Si)(Al)K, Cl
SiP
SiP
K, ClSi P
Si P
11
Non process elements-trouble areas
Element Digester Bleachplant
Evaporation Recoveryboiler
Recausticizing Lime kiln
K, Cl Plugging, corrosion
Ca* Scaling on heat surfaces / sieves
Scaling in washingequipment
Scaling on heat surfaces
Mg* Poor filterability, plugging of filter cloth
High ballast level in lime cycle
Si Scaling Poor filterability, plugging of filter cloth
Al(*) Scaling on heat surfaces
Mn, Fe* Break downperoxide
High ballast level in lime cycle
P High ballast level in lime cycle
Ba* Scaling in washingequipment
12
Green liquor handling- type of separation
Clarification– Separation through sedimentation– Driven by density difference between liquor and particles– ”Light” particles are more difficult to separate (i.e. carbon)– Clarification is aided by High temperature Low liquor strength Even inlet flow
Filtration– Separation by means of a filter cloth– Driven by differential pressure– Small particles are more difficult to separate, and also plug the cloth
General– ”Raw” green liquor contains approximately 1500 mg/l– ”Clear” liquor contains 20-100 mg/l (1-7% or raw liquor)
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Clarifier
Separation of dregs from green liquor through densitydifference
Dependable
Green liquor storage usuallyincluded in the tank
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OptiClear• Separation of dregs from
green liquor through densitydifference
• Diameter ½ of conventionalclarifier
• Separate green liquorstorage required
• Better process result, slightly higher operating cost than for conventional clarifier
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How does OptiClearTM work?
Dregs
Inlet distributor
V-notch overflow pipe
Drive for rake
Design feed rate
2 m3/m2,h
Rake
Green liquor
Polymer
Clear liquor
integrated with distributor arms.Drive for flocculation turbine.
Green liquor handling, OptiClear- Principle flowsheet
EQ tank OptiClear
PolymerRaw green liquor from smelt dissolver
Green liquor to storage
Dregs to dregs handling
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PDG filter
• Separation of dregs from green liquor through filtration. Differential pressure by compressor.
• No separate dregs washingequipment necessary
• Better green liquor clarity than with clarifier / OptiClear
Raw green liquor
Equalizing tank
Filtered WL
Causticized liquor
Green liquor tank
Filtered GL
HP condensate
Process description-PDG, dry discharge
Raw green liquor
Equalizing tank Green liquor tank
Filtered WL
Causticized liquor
Lime mud
Filtered GL
Weak wash
HP condensate
Process description-PDG, wet discharge
OptiClear – PDG comparison
OptiClear Suspended solids 40-80 mg/l 3-5% solids in discharge, remaining
green liquor Requires polymer Requires separate dregs handling
PDG Suspended solids 5-25 mg/l 45-55% solids in discharge,
remaining liquor mainly condensate Requires precoat / operates partly
as white liquor Higher power consumption May operate w / wo separate dregs
dregs handling Same basic design / commonality in
spares as PDW
Slide 21
Dregs Handling
White liquor plant fundamentals-dregs handling
Dregs is normally taken to landfill against a fee There may be regulations based on pH or
water soluble alkali, in extreme cases, alkali loss may also be accounted for
Dregs are– Washed to minimize alkali losses and to reduce pH of
discharged dregs. Normally none of this is critical.– Dried to reduce cost of landfull and transportation
The mill wants to have small amounts of dregs discharged to:– Minimize cost for landfill– Minimize cost for transport
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Dregs handling- type of separation
Centrifuge– Separation by means of a centrifugal force– Driven by difference in density in between particles and liquor– Poor separation of dregs particles from weak liquor
Incoming dregs– Consistency 1-10% of solids– Liquor part may be anything from green liquor to almost water
Filtration– Separation by means of a filter cloth– Driven by differential pressure– Dregs particles are generally very small, require lime mud precoat
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Dregs drum filter
• Washing and dewatering of dregs throughfiltration.
• Internal under-pressure by vacuum pump.
• Drum cloth is covered by a lime mudprecoat, which is discharged with the dregs
Process description-dregs filter
1. Centrifuge2. Dregs mix tank3. Standpipe4. Polymer dosing
Dregs handling, Centrifuge- Principle flowsheet
Centrifuge
Alfa Laval provides the equipment, Valmet provides process solution.
No lime mud required, thus dischargedamount lower than from filter
Polymer is used
Filter – centrifuge- comparison
Dregs filter Dewaters to 40-50% DS 2.5% water soluble alkali as NaOH Requires pre-coat
Centrifuge Dewaters to 30% DS Single stage operation yields 6%
water soluble alkali as NaOH Requires no pre-coat Compact installation Lower power consumption than with
pre-coat filter Requires polymer addition
INTERNAL
Slaking and Causticizing
Slaking and causticizing- Goodwin curve, too much or too little lime
TTA (NaOH), g/l
Causticizing degree at S*= 30%
Over liming
Optimal lime dosing
Under liming
Equilibrium(max)
76
78
80
82
84
86
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155 160 165 170
*With S=40 % all curves move downward with 0.8 % units
%Ca(OH)2 + Na2CO3 2 NaOH + CaCO3 + heat
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Process description-slaking and causticizing
Green liquor cooling
• Effect of high green liquor temperature– Improved green liquor sedimentation– Risk for over boiling in slaker
Cooler in front of slaker– Personal safety– Improved slaker operation by even
temperature– By installing it ahead of the slaker, the
benefit of high temperature in green liquor handling is kept
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Lime slaker
• Burnt lime and green liquormixed in slaker tank
• Slaking reaction completed, causticizing reaction started
• ”Causticized slurry” flowsfrom tank to classifierthrough bottom opening, flows upward to discharge pipe
• Unreacted lime (grits), discharged by screwconveyor
Lime Green liquor
Causticizers
• Causticized slurry from slaker to inlet at top of 1st
causticizer
• Flows downward throughopening in tray
• Flows upward through riserpipe, into causticizer 2
• Divided into compartments to give ”plug flow”
Cyclone
Scrubber
Agitator
Slaker
Classifier
Platform for service of classifier drive, and cleaning of grits pipe
Platform along the roof of the classifier
Typical layout -slaker
Slaking and causticizing-cooling principle
95°C
87°C(liquor phase)
-0,39 bar(g)-0.39 bar(g)87°C
(steam phase)
87°C
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Slaking and causticizing-cooling principle
-1
-0,8
-0,6
-0,4
-0,2
0
75 80 85 90 95 100Boiling point [°C]
Pressure[bar(g)]
(atmosphere)
(full vacuum)
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White Liquor Handling
Filtration– Separation by means of a filter cloth– Driven by differential pressure– Filterability has a substantial effect on capacity.
Filterability is affected by: Type and amount of deadload Overliming
White liquor handling- type of separation
Clarification– Separation through sedimentation
General– Causticized slurry contains 10-12% solids (lime mud)– The lime mud particles are larger than dregs particles– ”Clear” liquor contains 20-100 mg/l
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Recausticizing fundamentals-white liquor handling
Reduce particle content in white liquor
Maximize white liquor / green liquor ratio
– Reduce alkali content in lime mud
– Reduce upstream pumping
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High yield filtration- clarifier or tube filter
25 m3 WL
125 m3 GL
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High yield filtration- PDW filter
3 m3 WL
103 m3 GL
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Process description-slaking and causticizing
1. PDW filter2. WL separator3. Main compressor4. Booster compressor5. Lime mud vessel
White liquor
Lime mud (35%)
WL
WaterAir in / out
PDW filter- Main parts
Shaft and discs
Cake knock-off / wash
Sight glasses
Service doors
Doctors Gas lifter
Cake wash spray
Chute shower
Inside filter (plan view)
Gas lifter
Cake wash nozzle
Chute spray inletKnock off inlet
Scraper actuator
Chute
Inlet for Causticized slurry
Knock-off nozzles
Chute spray nozzles
Cake wash inlet
Gas lifter inlet
Filter vat
Gas inlet/outlet
Lime mud
Gas/white liquor
Sector with cloth
Filter bag
Perforated plate
Sector foot
Solids discharge
Doctor blade
Filter disc
Scraper board
Chute
PrecoatLime mud cake
Filter bag
49 Date/Title/Author
Pictures
Lime Mud Handling
Recausticizing fundamentals-lime mud handling
Even lime mud dryness and flow discharged to kiln (kiln operation)
Overall high lime mud dryness to reduce fuel consumption in kiln.
Low alkali content required for– Good kiln operation– TRS (total reduced sulfur)
Alkali is reduced by– Displacement washing in white liquor filter– Dilution washing in lime mud filter vat– Displacement washing in lime mud filter
Dryness and alkali reduction is directly dependent on load, so when operating a filter at low production the results will be better.
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Drum – Disc filter comparison
Drum filter Similar design as dregs filter Max filter area 95 m2
Disc filter Design a combination of disc filters
and drum filters Filter area 100 m2 and upward Require more surface area per ton
than drum filters
INTERNAL
Process description-lime mud drum filter
Process description-Disc filter for Lime Mud
54
Lime mud handling- type of separation
Filtration– Separation by means of a filter cloth– Driven by differential pressure– Filterability has a substantial effect on capacity. Filterability is affected by: Type and amount of deadload Overliming
General– Lime mud in storage tank has 35-40% solids, it is diluted to 25% in feed line– Dry lime mud ranges from 60-65% (high silica mills) to 80-82% (South American
mills). In Nordic countries 75-80%.
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Lime Kiln
120 t DS/24h 1933
1500 t DS/24h 1976
2000 t DS/24h 1986
3800 t DS/24h 1996
7000 t DS/24h 2006
15 t/d1905
450 t/d1991
600 t/d1992
1050 t/d1996
1250 t/d2014
Technology leading (TL)
To 1991: Unax
From 1984: Compax
Now: CB cooler
3 % fuel savings
3 % fuel savings
Valmet COMPAX Cooler Technology
FLSmidth Cross‐Bar™ cooler for larger lime kilns
2-stage Compax presentation July 2011 by Per H. Brix
Stationary seal,With direct cooling air
New design2-stage compax
Heat resistance stainless steel.
70mm Refractoryon inner shell
Kiln outlet sectors: Roundbars
Material outlet
Dedustchute
850°C
~300°C
2. Stage
Material flow
• Stronger cooler. (double amount of spokeplates in stage 2)
• 35% weight reduction on the rotating part, from 25T to 16T
• 16% weight reduction on the stationary part, from 19T to 16T
• Easier fabrication
• Better service access.
• No shovels = No contact between the rotary- and the stationary part.
• Easier and faster mounting time.
• Lower temperature in the new outer chamber compared with the “old intermediate chamber”
• Smaller space required for installing (good for retrofit).
Compax size: ø6000x2400 (200 Tpd)
550°C
New concept based on learnings from old installations
Design focussed on higest level of safety
Simple to operate
Able to operate 100 % on wood
Direct Wood Powder Firing
Lime Kiln Technology
Status for Wood Powder Firing:
Värö, Sweden: In operation
Enocell, Finland: Commisioning Nov. 2014
Munksund, Sweden: Commisioning Nov. 2014
Available equipment
White liquor plant fundamentals- main areas
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Recausticizing from A to Z
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Green liquor handling Slaking and causticizing White liquor handling Lime mud washing and dewatering
References
EPS contract designed for 6 600 m3 white liquor/day
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Design capacity: 6 600 m3 white liquor/day, 590 ton burnt lime
Contract : 2011Start-up : 2014
Scope of supply from Metso:• Project management • Main machinery• Engineering services• Platforms on machines• In-line instruments • Installation supervision• Training, check-out and start-up
System features: • Sumithickener™• Dregs drum filter• Green liquor cooler• Slaker• Causticizers• White liquor disc filter (PDW™) • Liime mud drum filters • Flash dryer• Burner with controls• Lime kiln• ESP
White liquor plant at Oji Nantong, China
White liquor plant at Oji Nantong, ChinaEPS contract designed for 6 600 m3 white liquor/day
70 JB/EHO/GUO January, 2013 Doc ID 30033627
Design capacity: 10 000 m3 white liquor/day, 900 burnt lime/day
Contract date: November 2005Start-up date: August 2007
EPC contract designed for 10 000 m3 white liquor/dayWhite liquor plant at Suzano Mucuri, Brazil
Scope of supply from Metso: Project management Main machinery Engineering services Building Platforms Instruments including distribution
transformers and switchgears Electrical equipment Piping and manual valves
Insulation Installation Training, check-out and start-up
System features: • PDG™ (Green liquor disc
filter)• Green liquor cooler• Slaker• Causticizers• PDW™ (White liquor disc
filter)• DLM (Lime mud disc filter)• Flash dryer• Burner with controls• Lime kiln• ESP
71
White liquor plant at Suzano Maranhão, Brazil
72
SLAKER
CAUSTICIZERS
GL COOLING
LIME HANDLING AND SILOS
EQUALIZINGTANK
PDG
PDG
DREGS FILTER GREEN LIQUOR TANK
PDW
LM FILTER
LIME MUDTANK
WHITE LIQUORTANKS
WEAK LIQUORTANK
SPILLTANK
Raw green liquorGL
White liquor
Weak liquor
SILOS
Lime milkSLAKER
FROM LIME KILNS
MAKE UP LIME
LM FILTER
DNCG collection system
EPC contract designed for 16 000 m3 white liquor/day
Recausticizing plant at Metsä Botnia Kemi, Finland
EPC contract designed for 7 000 m3 white liquor/day
73
Design capacity: 7 000 m3 white liquor/day
Contract date: May 2010Start-up date: October 2011
Scope of supply from Metso:• Project management • Main machinery• Engineering services• Platforms• Piping and manual valves• Insulation• Installation • Training, check-out and start-up
System features: • Green liquor clarifier• Centrifug• Green liquor cooler• Slaker• Causticizers• PDW™ (White liquor disc filter)• Storage tanks
Recausticizing plant at Metsä Botnia Kemi, Finland
Recausticizing74
EPC contract designed for 7 000 m3 white liquor/day
CONFIDENTIAL
Recausticizing rebuild at Södra Värö, Sweden
75
EPC contracts designed for 8 500 m3 white liquor/day
CMPC, Guaiba 2 EPC contract designed for 14 500 m3/d of White Liquor
Date Author Title76
SLAKER
CAUSTICIZERS
GL COOLING
EQUALIZINGTANK
PDG
PDG
DREGS FILTER GREEN LIQUOR TANK
PDW
LIME MUDTANK
WHITE LIQUORTANK
WEAK LIQUORTANK
SPILLTANK
Raw green liquorGL
Weak liquor
Lime milkSLAKER
LM FILTER
DNCG collection system REDILUTION TANK
Lime mud to kiln
LIME
ELETROSTATIC PRECIPITATOR
STACK
FUELLIME KILN
White liquor