Valmet White Liquor Plant Technology

Valmet White Liquor
Plant Technology
Western Canada BLURBAC
October 29, 2014
John B. Johnson II
Product Technology Manager
 Employment History (1981-present)
–
–
–
–
–
–
–
–
–
–
2
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
Licensing Agreement
 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
Background of Valmet white liquor plant
technologies
Envirotech
1984
Eimco
2007
Baker Hughes
F.L. Smidth
2013
2002
Kvaerner
Pulping
Dorr-Oliver
Eimco (GL&V)
2014
Metso
2002
Dorr-Oliver
1935-79
Hedemora
4
Valmet
Metso
GL&V
Kvaerner
Caustec
1993
1997
2006
Valmet– supplier of complete recovery systems
EVAPS™ evaporation
systems
5
RECOX™ recovery
boilers
White liquor plant
White liquor plant
fundamentals
White liquor plant fundamentals
Cooking
Washing &
screening
Oxygen
delignification
Pulp drying
Bleaching
Baling
Wood
handling
White liquor
preparation
Air pollution
control
Evaporation
Recausticizing
Lime kiln
Recovery
boiler
Steam turbine
Power
boiler
7
Bleaching chemical
and oxygen supply
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
Si P
K, Cl
P
K, Cl
(Al) Si
(Al)
K, Cl
Ca, Mg, Mn,
Fe, Ba (Al)
P Si
11
Si P
(Si)
Non process elements
-trouble areas
Element
Digester
Bleach
plant
Evaporation
Scaling on heat
surfaces /
sieves
Scaling in
washing
equipment
Si
Scaling
Al(*)
Scaling on heat
surfaces
Break down
peroxide
12
Poor filterability,
plugging of filter cloth
High ballast
level in lime
cycle
Poor filterability,
plugging of filter cloth
High ballast
level in lime
cycle
High ballast
level in lime
cycle
P
Ba*
Lime kiln
Scaling on heat
surfaces
Mg*
Mn, Fe*
Recausticizing
Plugging,
corrosion
K, Cl
Ca*
Recovery
boiler
Scaling in
washing
equipment
Green liquor handling
- type of separation
 General
– ”Raw” green liquor contains approximately 1500 mg/l
– ”Clear” liquor contains 20-100 mg/l (1-7% or raw liquor)
 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
13
Clarifier
 Separation of dregs from
green liquor through density
difference
 Dependable
 Green liquor storage usually
included in the tank
14
OptiClear
• Separation of dregs from
green liquor through density
difference
• Diameter ½ of conventional
clarifier
• Separate green liquor
storage required
• Better process result, slightly
higher operating cost than for
conventional clarifier
15
How does OptiClearTM work?
Drive for rake
integrated with distributor
arms.
Drive for flocculation
turbine.
Polymer
Green liquor
V-notch overflow pipe
Design feed rate
2 m3/m2,h
Inlet distributor
Rake
Clear liquor
Dregs
Green liquor handling, OptiClear
- Principle flowsheet
Raw green liquor
from smelt dissolver
Polymer
Green liquor to
storage
EQ tank
OptiClear
Dregs to dregs
handling
17
PDG filter
• Separation of dregs from
green liquor through filtration.
Differential pressure by
compressor.
• No separate dregs washing
equipment necessary
• Better green liquor clarity
than with clarifier / OptiClear
Process description
-PDG, dry discharge
HP condensate
Causticized liquor
Raw green liquor
Filtered WL
Filtered GL
Equalizing tank
Green liquor tank
Process description
-PDG, wet discharge
HP condensate
Causticized liquor
Raw green liquor
Filtered WL
Filtered GL
Equalizing tank
Green liquor tank
Lime mud
Weak wash
OptiClear – PDG comparison
OptiClear
PDG
 Suspended solids 40-80 mg/l
 Suspended solids 5-25 mg/l
 3-5% solids in discharge, remaining  45-55% solids in discharge,
green liquor
remaining liquor mainly condensate
 Requires polymer
 Requires separate dregs handling
 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
23
Dregs handling
- type of separation
 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
 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
24
Dregs drum filter
• Washing and dewatering of dregs through
filtration.
• Internal under-pressure by vacuum pump.
• Drum cloth is covered by a lime mud
precoat, which is discharged with the
dregs
Process description
-dregs filter
Dregs handling, Centrifuge
- Principle flowsheet
1.
2.
3.
4.
Centrifuge
Dregs mix tank
Standpipe
Polymer dosing
Centrifuge
 Alfa Laval provides the equipment,
Valmet provides process solution.
 No lime mud required, thus discharged
amount lower than from filter
 Polymer is used
INTERNAL
Filter – centrifuge
- comparison
Dregs filter
Centrifuge
 Dewaters to 40-50% DS
 Dewaters to 30% DS
 2.5% water soluble alkali as NaOH
 Single stage operation yields 6%
water soluble alkali as NaOH
 Requires pre-coat
 Requires no pre-coat
 Compact installation
 Lower power consumption than with
pre-coat filter
 Requires polymer addition
Slaking and
Causticizing
Slaking and causticizing
- Goodwin curve, too much or too little lime
Causticizing degree at S*= 30%
Ca(OH)2 + Na2CO3
% 88
86
84
Equilibrium(max)
82
Over liming
80
Optimal lime dosing
78
Under liming
76
155
160
165
170
TTA (NaOH), g/l
31
*With
S=40 % all curves move downward with 0.8 % units
2 NaOH + CaCO3 + heat
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
33
Lime slaker
Lime
Green liquor
•
Burnt lime and green liquor
mixed in slaker tank
•
Slaking reaction completed,
causticizing reaction started
•
”Causticized slurry” flows
from tank to classifier
through bottom opening,
flows upward to discharge
pipe
•
Unreacted lime (grits),
discharged by screw
conveyor
Causticizers
•
Causticized slurry from
slaker to inlet at top of 1st
causticizer
•
Flows downward through
opening in tray
•
Flows upward through riser
pipe, into causticizer 2
•
Divided into compartments to
give ”plug flow”
Typical layout
-slaker
Scrubber
Agitator
Cyclone
Platform along the roof of the
classifier
Platform for service of classifier
drive, and cleaning of grits pipe
Slaker
Classifier
Slaking and causticizing
-cooling principle
-0.39 bar(g)
87°C
(steam phase)
-0,39 bar(g)
87°C
(liquor phase)
87°C
95°C
37
Slaking and causticizing
-cooling principle
Pressure[bar(g)]
0
(atmosphere)
-0,2
-0,4
-0,6
-0,8
-1
(full vacuum)
75
80
85
90
Boiling point [°C]
38
95
100
White Liquor Handling
White liquor handling
- type of separation
 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
 Clarification
– Separation through sedimentation
 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
40
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
41
High yield filtration
- clarifier or tube filter
125 m3 GL
25 m3 WL
42
High yield filtration
- PDW filter
103 m3 GL
3 m3 WL
43
Process description
-slaking and causticizing
Air in / out
Water
White liquor
WL
1.
2.
3.
4.
5.
PDW filter
WL separator
Main compressor
Booster compressor
Lime mud vessel
Lime mud (35%)
PDW filter
- Main parts
Sight glasses
Cake wash spray
Service doors
Cake knock-off /
wash
Chute shower
Shaft and discs
Doctors
Gas lifter
Inside filter (plan view)
Gas inlet/outlet
Cake wash nozzle
Cake wash inlet
Knock-off nozzles
Gas lifter inlet
Gas/
white
liquor
Chute spray nozzles
Scraper actuator
Lime
mud
Chute
Inlet for Causticized
slurry
Filter vat
Knock off inlet
Chute spray inlet
Gas lifter
Sector with cloth
Perforated
plate
Sector foot
Filter
bag
Solids discharge
Filter bag
Filter disc
Precoat
Lime mud cake
Doctor blade
Scraper board
Chute
Pictures
49
Date/Title/Author
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.
51
Drum – Disc filter comparison
INTERNAL
Drum filter
Disc filter
 Similar design as dregs filter
 Design a combination of disc filters
and drum filters
 Max filter area 95 m2
 Filter area 100 m2 and upward
 Require more surface area per ton
than drum filters
Process description
-lime mud drum filter
Process description
-Disc filter for Lime Mud
54
Lime mud handling
- type of separation
 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%.
 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
55
Lime Kiln
3800 t
DS/24h 1996
7000 t
DS/24h 2006
2000 t DS/24h
1986
1500 t DS/24h
1976
120 t DS/24h
1933
15 t/d
1905
450 t/d
1991
600 t/d
1992
1050 t/d
1996
1250 t/d
2014
Technology leading (TL)
3 % fuel savings
To 1991: Unax
From 1984: Compax
Now: CB cooler
3 % fuel savings
Valmet COMPAX Cooler Technology
FLSmidth Cross‐Bar™ cooler for larger lime kilns
New design
2-stage compax
Compax size: ø6000x2400 (200 Tpd)
•
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).
Dedust
chute
Stationary seal,
With direct cooling air
Heat resistance
stainless steel.
Kiln outlet
sectors:
Roundbars
850°C Material flow
550°C
2. Stage
2-stage Compax presentation July 2011 by Per H. Brix
~300°C
70mm
Refractory
on inner shell
Material
outlet
Direct Wood Powder Firing
New concept based on
learnings from old installations
Design focussed on higest level
of safety
Simple to operate
Able to operate 100 % on wood
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
66
Recausticizing from A to Z
Green liquor handling
67
Slaking and causticizing
White liquor handling
Lime mud washing and
dewatering
References
White liquor plant at Oji Nantong, China
EPS contract designed for 6 600 m3 white liquor/day
Design capacity: 6 600 m3 white liquor/day, 590 ton burnt lime
Contract : 2011
Start-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
•
•
•
•
•
•
•
•
•
•
•
69
White liquor plant at Oji Nantong, China
EPS contract designed for 6 600 m3 white liquor/day
70
JB/EHO/GUO
January, 2013
Doc ID 30033627
White liquor plant at Suzano Mucuri, Brazil
EPC contract designed for 10 000 m3 white liquor/day
Design capacity: 10 000 m3 white liquor/day, 900 burnt lime/day
Contract date: November 2005
Start-up date: August 2007
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



71
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
•
White liquor plant at Suzano Maranhão, Brazil
EPC contract designed for 16 000 m3 white liquor/day
LIME HANDLING AND SILOS
MAKE UP
LIME
PDG
GL COOLING
SILOS
FROM
LIME KILNS
Lime milk
SLAKER
PDG
Raw green liquor
GL
SLAKER
CAUSTICIZERS
EQUALIZING
TANK
DREGS FILTER
GREEN LIQUOR
TANK
PDW
WHITE LIQUOR
TANKS
LM FILTER
White liquor
LM FILTER
LIME MUD
TANK
DNCG collection system
Weak liquor
SPILL
TANK
72
WEAK LIQUOR
TANK
Recausticizing plant at Metsä Botnia Kemi, Finland
EPC contract designed for 7 000 m3 white liquor/day
Design capacity: 7 000 m3 white liquor/day
Contract date: May 2010
Start-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
73
Recausticizing plant at Metsä Botnia Kemi, Finland
EPC contract designed for 7 000 m3 white liquor/day
74
Recausticizing
CONFIDENTIAL
Recausticizing rebuild at Södra Värö, Sweden
EPC contracts designed for 8 500 m3 white liquor/day
75
CMPC, Guaiba 2
EPC contract designed for 14 500 m3/d of White Liquor
GL COOLING
PDG
Lime milk
SLAKER
PDG
Raw green liquor
GL
EQUALIZING
TANK
STACK
ELETROSTATIC
PRECIPITATOR
SLAKER
CAUSTICIZERS
DREGS FILTER GREEN LIQUOR
TANK
PDW
White liquor
LM FILTER
WHITE LIQUOR
TANK
Lime mud to kiln
DNCG collection system
LIME MUD
TANK
REDILUTION
TANK
Weak liquor
SPILL
TANK
76
Date Author Title
WEAK LIQUOR
TANK
FUEL
LIME KILN
LIME