Transcript Document 7293657

Black Liquor Gasification
Design Project
GP Wauna
Gasifier Design
Justin Aldrich, Adam Cooper, Khoa Hua, Jim Jollimore
Mill Integration
Sean Noste, Steve Ross, John Salvatier, Peter Siedenburg, Nilar Thein-chen
Environmental
Cody Hargrove, Sonha Pham, Claire Schairbaum, Larissa Zuk
Economics
Darrow Conley, Ryan McMahon, Vinh Nguyen, Suzy Quach
Agenda
 Gasifier Design
 Mill Integration
 Environmental
 Economics
High Temperature Gasification
Image Source: http://www.eng.utah.edu/~whitty/blackliquor/colloquium2003/pdfs_handouts/5.6.Lindblom-Chemrec_Handout.pdf
High Temperature Gasification
 Syngas Properties:
 Heating Value
Higher Heating
Value (MJ/kg)
Low Temp
Gasifier
High Temp
Gasifier
Natural Gas
20.95
9.32
42.5
Gasifier values from Larson 2003. Natural gas value from Wikipedia.
 Sulfur
H2S in Syngas
(%mol)
Low Temp
Gasifier
High Temp
Gasifier
2.250
1.737
H2S in Syngas values from Larson 2003.
High Temperature Gasification
 Effect on Causticization Load
Low Temp High Temp
Gasifier
Gasifier
Sulfur (%)
~90%
~50%
High Temp
Booster
~15%
 Reliability
 Weyerhauser, New Bern, Chemrec Booster 1996.
Low Temperature: Pros
 Low Temperature
 Better return on energy
 Ease of getting chemicals back
 H2S is in a gaseous form
 Proven system that is currently running
 Norampac Trenton Ontario
 Use heat to produce needed steam and
electricity
Low Temperature: Con
 Need additional equipment
to recover Chemicals
 Air scrubbers to recover SO2
 Higher initial cost than High
Temp
 ~32% higher initial startup
cost
BL Solids @ 67% Solids
Vent
Cooling Water
95% O2,
20°C
Raw Syngas, 122°C
High
Temp
Gasifier
O2
Plant
To Lime
Kiln
1000°C
35 bar
165 TPD
Air,
20°C
Cooled Green
Liquor
132°C
Raw
Syngas
200°C
35 bar
2 Stage
Gas
Cooler or
Heat
Exchanger
LP Steam?
Cooling
Water?
GL Cond
HX
Clean
Syngas
40°C
~30 Bar
H2S and CO2
High
Sulfidity
White Liquor
WL
Scrubber
White
Liquor
Selexol
Stripper
40 °C
~30 bar
Selexol
Absorber
40 °C
~30 bar
Trim
Cooler
Raw Syngas, 40°C
LP
Steam
Raw Syngas, 600°C
Steam
Cooling
Water
Clean Syngas
Low
Temp
Gasifier
650°C
BL Solids @ 67%
Solids
1.2 bar
165 TPD
PC Heater
Flue Gas
HX
Low
Pressure
Superheater
Superheated
Steam
Dregs
Mix Tank
& Filter
H2S and CO2
High
Sulfidity
White Liquor
Or Green
Liquor
WL
Scrubber
LP
Steam
White
Liquor
LP Steam
or Warm
Water
Clean
Syngas
40°C
Na2CO3
Selexol
Stripper
40 °C
~25 bar
Heat
Exchanger
Compressor
Selexol
Absorber
40 °C
~25 bar
Trim
Cooler
Raw Syngas,
40°C
Claus Plant
 Converts H2S gas into elemental sulfur
 Has two parts: thermal stage and catalytic
stages
 Operates at moderate temperatures (340° C to
200° C)
 Uses Titanium Dioxide or Alumina as a catalyst
 94 to 97% efficiency depending on the number
of catalytic stages
2H2S + O2 → S2 +2H2O
Liquor Scrubbing
 Product gas stream contains CO2 and H2S
 Scrubbing CO2 generates Na2CO3 which increase the
lime kiln load
 Use the NaOH in the liquor to regain the pulping
chemical Na2S
 85% efficiency at sulfur recovery
H2S + 2NaOH → Na2S + 2H2O
CrystaSulf
 Uses SO2 to convert H2S into elemental sulfur
 Operates at lower temperatures (170 °C)
 Claims to be more economical for 0.2 to 30
LTPD H2S flows
 Uses hydrocarbons and amines as catalysts
2H2S + SO2 → ⅜ S8 + 2H2O + 33kcal/gmole
Mill Integration: Objective
 Energy and Mass Balance on Process
 Create WinGEMS Model
 Determine Impact of Gasifier
 Effect of Burning Syngas in Lime Kiln
 Transportation of Syngas
Schematic from Wauna Mill
Steam Balance Calculation
Steam Usage
Evaporators
Concentrator
PM 1,2
PM 5
PM 6,7
Bleach Plant
Recaust
Kamyr
M&D Sawd
Total
KPPH
83
39
36
32
23
90
18
54
38
413
Steam Produced
KPPH
Recovery Boiler
Power Boiler
Fluidized Bed Boiler
431
91
106
Total
628
Total From PPT
557
Calculation Comparison
According
Our
to Mill
Calculations
Extra Steam
(KPPH)
Black Liquor,
Redirected
(Mlbs/hr of black
liquor solids)
50
144
13.8
38.51
WinGEMS Full Mill
Kraft Pulp Mill and Recovery
CaO
Steam
Make-Up
vents
Fresh shower water
Wood chips
Chip
Black
presteam
2116 od st/day
Green liquor
1800 gal total/min
White liquor
clarifier
581.3 gal total/min
CONTINUOUS DIGESTER
To
16.1 mt/hr
31 psig
Flash
tank
tank
Clarified white liquor
TTA: 130 g/l as NaOH
Brownstock
Flash
clarifier
724 gal total/min
liquor
scrubber
White liquor
Clarified green liquor
Slaker
Unbleached pulp
washers
1003 od st/day
1302 gal total/min
4.2 gal total/min
0.0002 g/l as NaOH EA
34 cons%
Makeup
NaOH
1653 gal total/min
10 cons%
Grits
Makeup
chemicals
to mix tank
Dregs
Wash
Filtrate
zone
Weak
Flue gas
black
Spills
Weak wash
liquor
Scrubber
177.2 gal total/min
Weak wash to SDT
36 cons%
1577.1 gal total/min
687 gal total/min
White liquor
16.5 %mass
to digesters
Pulp yield:
47.4 %
Evaporators
Recovery
Shower
Boiler
water
Strong black liquor
Air
302.2 gal total/min
Flue
Lost
gas
lime dust
EA: 107 g/l as NaOH
Sulfidity: 28 %
Digester
581 gal total/min
flash steam
64 %mass
Spent acid
Mud
Lime Kiln
washer
Fresh water
makeup
Recovered
Fuel
Makeup chemicals
sulfur
BL spills Tall Condensate
oil
Created By Pacific Simulation
542 gal total/min
Stream 59 flow is manipulated to
achieve a TTA of 130 g/l as NaOH
in the green liquor, stream 50.
Lime
SDT
Air
Smelt
Mud washer and filter filtrates
WinGEMS Modification
White liquor
Kraft Pulp Mill and Recovery
0 gal total/min
Wood chips
420 od st/day
Unbleached pulp
0 od st/day
0 gal total/min
0 g/l as NaOH EA
CaO
Make-Up
Steam
vents
Chip
presteam
Black
liquor
1000 od st/day
To
scrubber
Flash
tank
0 mt/hr
-14.7 psig
Flash
tank
CONTINUOUS DIGESTER
Fresh shower water
Wood chips
White liquor
clarifier
Clarified green liquor
0 gal total/min
TTA: 0 g/l as NaOH
Brownstock
washers
Clarified white liquor
Slaker
Makeup
NaOH
0 gal total/min
0 cons%
0 gal total/min
0 cons%
Grits
Makeup
chemicals
to mix tank
Wash
zone
Weak
black
liquor
0 gal total/min
0 %mass
Green liquor
clarifier
1800 gal total/min
Dregs
Filtrate
Flue gas
Spills
Weak wash
Scrubber
0 gal total/min
0 cons%
Weak wash to SDT
1300 gal total/min
White liquor
to digesters
Shower
water
Pulp yield:
0%
Flue
gas
Air
Lost
lime dust
Evaporators
Recovery
Boiler
Strong black liquor
0 gal total/min
0 %mass
Lime
Mud washer and filter filtrates
Makeup chemicals
Spent acid
Recovered
sulfur
BL spills
Tall
oil
Condensate
SDT
Air
Smelt
Digester
flash steam
Mud
washer
Lime Kiln
Fuel
EA: 0 g/l as NaOH
Sulfidity: 0 %
0 gal total/min
Fresh water
makeup
626 gal total/min
Stream 59 flow is manipulated to
achieve a TTA of 130 g/l as NaOH
in the green liquor, stream 50.
Burning Syngas in Lime Kiln
 Combustion in kiln and TADs
 Sulfur needs to be scrubbed from syngas
 Send scrubbed sulfur to kiln for recovery
 Combustion in kiln only
 No need to scrub sulfur from syngas
 Potential increase in ball and ring formation
from sulfur
Transportation of Syngas
 Hydrogen is main component in syngas
 Amount of carbon in steel decreases when in
contact with hydrogen creating pockets
 Methane forms in pockets inside the steel
causing steel to become brittle
 Choice of material is very important
Mill Integration: Conclusion
 Modified WinGEMs Simulation Adequately
 Future comparison of High and Low Temp
 Using WinGEMS
 Comparing chemical balances
 Steam balance
 Load on lime kiln
 Optimal use of syngas
Air Emissions
 Black liquor gasifier system should have low air
emissions including:
 CO2 (Carbon Dioxide)
 SO2 (Sulfur Dioxide)
 NOX (Nitride Oxides)
 VOCs (volatile organic compounds)
 TRS emissions (Total Reduced Sulfur)
 A lot of contaminant removal is required to recover the
pulping chemicals from the gas
Air Emissions: High Temp vs. Low Temp
Pollutant/Parameter
TRS
PM
SO2
NOX
VOC
CO
Emissions (Low T)
0.017 tpd (averaged
from over a year)
0.275 tpd (averaged
from over a year)
2.507 tpd (averaged
from over a year)
Emissions (High T)
0.014 tpd (averaged
from over a year)
0.238 tpd (averaged
from over a year)
3.439 tpd (averaged
from over a year)
1.402 tpd (averaged
from over a year)
0.088 tpd (averaged
from over a year)
3.014 tpd (averaged
from over a year)
1.272 tpd (averaged
from over a year)
0.074 tpd (averaged
from over a year)
2.807 tpd (averaged
from over a year)
Figure 1. Emissions estimated for low temperature and high temperature gasifiers. The values were calculated using a 353 day operating
schedule per year. Source: Larson, E.D., & Consonni, S., & Katofsky, R.E. (2003). A Cost-Benefit Assessment of Biomass Gasification
Power Generation in the Pulp and Paper Industry.
Air Emissions: Mill Limits
Pollutant/Parameter
TRS
PM
SO2
Limit
0.218 tpd (averaged
from over a year)
4.266 tpd (averaged
from over a year)
5.147 tpd (averaged
from over a year)
NOX
6.133 tpd (averaged
from over a year)
VOC
2.317 tpd (averaged
from over a year)
13.78 tpd (averaged
from over a year)
CO
Figure 2. These are emission standards for the Georgia-Pacific mill in Wauna. Source: Oregon Department of
Environmental Quality. (2005). Oregon Title V Operating Permit (Permit Number 04-0004). Portland, OR.
Water Emissions & Usage
 Two water issues associated with the addition of gasifier:
 Water Usage
 Thermal Pollution
 Secondary treatment facility has a maximum capacity of
42 million gal/day.
 In 2007, GP Wauna averaged 27.3 million gal/day.
 There is no way the gasifier will cause the mill to
increase its water consumption by 15 million gal/day.
Thermal Pollution
 Maximum allowable discharge temperature from
secondary treatment plant is 20 °C.
 In 2007, GP Wauna’s secondary treatment was fed
waste water at a temperature of 29.3 °C.
 The addition of 7.2 million gpd at 40 °C from the gasifier
could potentially raise the temperature of the discharge
waste water stream by 2 °C.
Syngas Exposure
 Carbon Monoxide – PEL 50 ppm
 EXTREMELY toxic
 Flammable
 Hydrogen – No PEL
 Not toxic; excessive exposure may lead to
asphyxiation
 EXTREMELY flammable
 Carbon Dioxide – PEL 5,000 ppm
 Toxic
Syngas Storage
 Store in well ventilated areas.
 Store where temperature is less than 50 °C
 Remove sparking and ignition hazards
 Stainless steel is satisfactory
• Risk of embrittlement with hydrogen
• Syngas is not pure hydrogen, so
embrittlement risk is minimal
Natural Gas Usage
Natural gas
(Therms/year)
Total CO2 Emissions
(metric tons/year)
Lim Kiln
4,029,600
3,641
PM 1,2
1,825,000
1,649
PM 5
4,197,500
3,792
PM 6
8,030,000
7,255
PM 7
9,125,000
8,244
Bed Boiler
1,314,000
1,187
LVHC
36,500
Total
28,557,600
33
25,802
Raw Syngas Component
Component
Volume %
H2O
63.7
H2
CO
Component
Volume %
CO
13.1
H2
13.7
CH4
0.75
H2 O
63.7
CO2
CO2
7.6
H2 S
0.67
CH4
COS
0.03
N2
0.14
H2S
Ar
0.37
13.7
13.1
7.6
0.75
0.67
Ar
0.37
N2
0.14
COS
0.03
Raw Syngas Produced
BL enter Gasifer
(dry lbs/hour)
Raw Syngas
(kg/year)
Raw Syngas Natural Gas Needed
(Therms/year)
(Therms/year)
High Temp
13800
84,738,715
7,485,923
21,071,677
Low Temp
13800
110,549,826
21,952,785
6,604,815
CO2 Produced
Syngas
(Therms/year)
Syngas
(kg/year)
CO
(kg/year)
CO2
(kg/year)
CO2
(metric
tons/year)
Natural Gas High
21,071,677
52,307,341
29,889,909
19,038,159
19,038
Syngas High
7,485,923
18,582,702
2,415,751
2,950,980
2,951
Total
21,989
Natural Gas Low
6,604,815
16,395,481
9,368,846
5,967,418
5,967
Syngas Low
1,952,785
54,494,561
7,084,293
8,653,875
8,654
Total
14,621
25,801,653
25,802
Total
25,802
Natural Gas only
28,557,600
70,890,042
40,508,596
Social Impact
 Benefit
 Improve the economics
 Greenhouse gases reduction
 Lower net emission of CO2
 Possible downside
 Water thermal discharge
Economics: Agenda





Major Equipment
Summary of Calculation
Capital Cost Analysis
Cost Reduction
Conclusions
Major Equipment and Components
 Gasifier
 Air Separation Unit
 Sulfur Recovery Unit (SRU)
 Selexol/Rectisol
 Green Liquor Scrubber
 Gas Cooler (Heat Exchangers)
Summary of Calculation
 Capital cost adapted from Eric Larson’s A Cost-Benefit Assessment of
Biomass Gasification Power Generation in the Pulp and Paper Industry
 Adjustment made with High Temp
 2002$ inflated to 2008$
 Scaled to Wauna specifications using 6-tenths factor
 2576.8 tons BL/day  165.6 tons BL/day
 Lang factor used to estimate indirect costs from direct costs
Capital Cost Analysis
Cost From Larson Article
Direct Cost
Gasifier Island and Green Liquor Filter
Air Separation Unit
Process gas handling
Gas clean up and sulfur recovery
Auxiliaries
Total Direct
Indirect cost
Construction Indirect
Sales Tax, Customs, Duties
Engineering
Contingency
Escalation
Spare Parts
Licensing Fee
Owner's Costs
$ Million
Low Temp
9.680
$ Million
High Temp
11.607
7.935
6.997
9.713
1.321
3.188
27.711
22.729
5.607
1.821
0.134
1.812
2.525
5.860
3.618
1.299
0.081
2.914
1.239
Total Indirect
19.380
10.043
Total Installed
47.090
32.772
2.513
Cost Reduction Analysis
Flow Syngas (kg/s)
Heating value (MJ/kg)
NG Heating Value (MJ/kg)
Syngas Energy Production (Therm/Day)
NG replacement (Therm/Day)
Savings by using Syngas ($ Million/Yr)
Total Installed ($ Million)
ROI (%)
Low Temp
23.76
High Temp
24.24
20.95
42.50
407,632
9,591.55
3.081
87.966
9.32
42.50
185,006
4,353.18
1.398
66.300
6.54
4.27
Conclusions
 Low Temp Gasification
 Higher up front cost
 Higher ROI
 Better at replacing natural gas with Syngas
 High Temp Gasification
 Lower up front cost
 Lower ROI
 Consult with design team
 Stability against Natural Gas Increase
Questions