Black Liquor Gasification Design Project

GP Wauna

Gasifier DesignJustin Aldrich, Adam Cooper, Khoa Hua, Jim Jollimore

Mill IntegrationSean Noste, Steve Ross, John Salvatier, Peter Siedenburg, Nilar Thein-chen

EnvironmentalCody Hargrove, Sonha Pham, Claire Schairbaum, Larissa Zuk

EconomicsDarrow 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

Sulfur

Low Temp Gasifier

High Temp Gasifier

Natural Gas

Higher Heating Value (MJ/kg)

20.95 9.32 42.5

Low Temp Gasifier

High Temp Gasifier

H2S in Syngas

(%mol)2.250 1.737

H2S in Syngas values from Larson 2003.

Gasifier values from Larson 2003. Natural gas value from Wikipedia.

High Temperature Gasification

Effect on Causticization Load

ReliabilityWeyerhauser, New Bern, Chemrec Booster 1996.

Low Temp Gasifier

High Temp Gasifier

High Temp Booster

Sulfur (%) ~90% ~50% ~15%

Low Temperature: Pros

Low TemperatureBetter return on energy

Ease of getting chemicals backH2S is in a gaseous form

Proven system that is currently runningNorampac 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

Trim Cooler

Raw Syngas, 40°C

2 Stage Gas

Cooler orHeat

Exchanger

O2 Plant

High Temp

Gasifier1000°C35 bar

165 TPD

GL CondHX

SelexolAbsorber

40 °C~30 bar

SelexolStripper40 °C

~30 bar

To Lime Kiln

BL Solids @ 67% Solids

Air, 20°C

Vent

Cooled Green Liquor132°C

Cooling Water

200°C35 bar

Raw Syngas

Raw Syngas, 122°C

Clean Syngas

40°C~30 Bar

LP Steam

WL Scrubber

H2S and CO2

High Sulfidity White Liquor

95% O2, 20°C

LP Steam?

Cooling Water?

White Liquor

Raw Syngas, 40°C

Raw Syngas, 600°C

Trim Cooler

SelexolAbsorber

40 °C~25 bar

SelexolStripper40 °C

~25 bar

Clean Syngas

40°C

LP Steam

WL Scrubber

H2S and CO2

High Sulfidity White LiquorOr Green Liquor

White Liquor

Low Temp

Gasifier650°C1.2 bar

165 TPD

Low Pressure

Superheater

BL Solids @ 67% Solids

Mix Tank & Filter

Na2CO3

Dregs

Clean Syngas

PC Heater Flue Gas

HX

Steam

Superheated Steam

Heat Exchanger

Cooling Water

LP Steam or Warm Water

Compressor

Claus PlantConverts 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 catalyst94 to 97% efficiency depending on the number

of catalytic stages

2H2S + O2 → S2 +2H2O

Liquor Scrubbing

Product gas stream contains CO2 and H2SScrubbing 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 recoveryH2S + 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 CalculationSteam Usage KPPHEvaporators 83Concentrator 39PM 1,2 36PM 5 32PM 6,7 23Bleach Plant 90Recaust 18Kamyr 54M&D Sawd 38Total 413

Steam Produced KPPHRecovery Boiler 431Power Boiler 91Fluidized Bed Boiler 106

Total 628Total From PPT 557

Calculation Comparison

According to Mill

Our Calculations

Extra Steam (KPPH)

50 144

Black Liquor, Redirected(Mlbs/hr of black liquor solids)

13.8 38.51

WinGEMS Full Mill

Created By Pacific Simulation

WinGEMS Modification

Wood chips

420 od st/day

0 gal total/min0 cons%

0 gal total/min0 cons%

0 gal total/min0 %mass

0 gal total/min0 cons%

0 mt/hr-14.7 psig

Pulp yield: 0 %

1800 gal total/min

0 gal total/min0 %mass

Blackliquor

626 gal total/min

Slaker

Lime Kiln Mudwasher

White liquorclarifier

0 od st/day0 gal total/min0 g/l as NaOH EA

1000 od st/day

0 gal total/min

CondensateBL spills Talloil

Mak

eup

chem

ical

s

Air

Green liquorclarifier

Smelt

Filtrate

1300 gal total/min

Weakblackliquor

EA: 0 g/l as NaOHSulfidity: 0 %0 gal total/min

0 gal total/minTTA: 0 g/l as NaOH

Grits

Flue gas

Toscrubber

Spent acid

ScrubberSpills

Wood chips

CaOMake-Up

Brownstockwashers

Strong black liquor

Digesterflash steam

Evaporators

Showerwater

Fresh watermakeup

Mud washer and filter filtrates

Kraft Pulp Mill and Recovery

Flashtank

Flashtank

Chippresteam

Washzone

CO

NT

INU

OU

S D

IGE

ST

ER

Fresh shower water

White liquor

Unbleached pulp

RecoveryBoiler

SDT

Weak wash to SDT

Lime

AirLost

lime dust

Weak wash

Clarified white liquor

Fuel

Fluegas

MakeupNaOH

Makeupchemicalsto mix tank

White liquorto digesters

Clarified green liquor

Dregs

Steamvents

Recoveredsulfur

Stream 59 flow is manipulated toachieve a TTA of 130 g/l as NaOHin the green liquor, stream 50.

Burning Syngas in Lime Kiln

Combustion in kiln and TADsSulfur needs to be scrubbed from syngasSend scrubbed sulfur to kiln for recovery

Combustion in kiln onlyNo need to scrub sulfur from syngas

Potential increase in ball and ring formation from sulfur

Transportation of SyngasHydrogen is main component in syngasAmount of carbon in steel decreases when in

contact with hydrogen creating pocketsMethane forms in pockets inside the steel

causing steel to become brittleChoice of material is very important

Mill Integration: Conclusion

Modified WinGEMs Simulation AdequatelyFuture comparison of High and Low Temp

Using WinGEMSComparing chemical balancesSteam balanceLoad on lime kilnOptimal 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

3.439 tpd (averaged from over a year)

2.507 tpd (averaged from over a year)

0.017 tpd (averaged from over a year)

Emissions (Low T) Emissions (High T)

0.014 tpd (averaged from over a year)

0.074 tpd (averaged from over a year)

3.014 tpd (averaged from over a year)

2.807 tpd (averaged from over a year)

0.275 tpd (averaged from over a year)

0.238 tpd (averaged from over a year)

Pollutant/Parameter

1.402 tpd (averaged from over a year)

1.272 tpd (averaged from over a year)

0.088 tpd (averaged from over a year)

SO2

TRS

PM

NOX

VOC

CO

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

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.

0.218 tpd (averaged from over a year)

NOX

VOC

CO

4.266 tpd (averaged from over a year)

5.147 tpd (averaged from over a year)

2.317 tpd (averaged from over a year)

6.133 tpd (averaged from over a year)

13.78 tpd (averaged from over a year)

Pollutant/ParameterTRS

Limit

PM

SO2

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 ExposureCarbon Monoxide – PEL 50 ppm

EXTREMELY toxicFlammable

Hydrogen – No PELNot toxic; excessive exposure may lead to

asphyxiationEXTREMELY flammable

Carbon Dioxide – PEL 5,000 ppmToxic

Syngas StorageStore in well ventilated areas.Store where temperature is less than 50 °CRemove sparking and ignition hazardsStainless 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 33

Total 28,557,600 25,802

Raw Syngas Component

Component Volume %

CO 13.1

H2 13.7

CH4 0.75

H2O 63.7

CO2 7.6

H2S 0.67

COS 0.03

N2 0.14

Ar 0.37

Raw Syngas Produced

 BL enter Gasifer

(dry lbs/hour)Raw Syngas

(kg/year)Raw Syngas

(Therms/year)Natural Gas Needed

(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

Natural Gas only 28,557,600 70,890,042 40,508,596 25,801,653 25,802

        Total 25,802

Social ImpactBenefit

Improve the economics Greenhouse gases reduction

Lower net emission of CO2

Possible downsideWater 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/RectisolGreen 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 AnalysisCost From Larson Article $ Million $ MillionDirect Cost Low Temp High TempGasifier Island and Green Liquor Filter 9.680 11.607Air Separation Unit 7.935Process gas handling 6.997Gas clean up and sulfur recovery 9.713 3.188Auxiliaries 1.321Total Direct 27.711 22.729

Indirect costConstruction Indirect 5.607 1.821Sales Tax, Customs, Duties 0.134Engineering 5.860 1.812Contingency 3.618 2.525EscalationSpare Parts 1.299 1.239Licensing Fee 0.081Owner's Costs 2.914 2.513Total Indirect 19.380 10.043

Total Installed 47.090 32.772

Cost Reduction AnalysisLow Temp High Temp

Flow Syngas (kg/s) 23.76 24.24

Heating value (MJ/kg) 20.95 9.32

NG Heating Value (MJ/kg) 42.50 42.50

Syngas Energy Production (Therm/Day) 407,632 185,006

NG replacement (Therm/Day) 9,591.55 4,353.18

Savings by using Syngas ($ Million/Yr) 3.081 1.398

Total Installed ($ Million) 87.966 66.300

ROI (%) 6.54 4.27

ConclusionsLow Temp Gasification

Higher up front costHigher ROIBetter at replacing natural gas with Syngas

High Temp Gasification Lower up front costLower ROI

Consult with design teamStability against Natural Gas Increase

Questions