Weiland (Multiphase Flow Science Workshop), May 4-6, 2010

Kinetics of Coal/Biomass Co-gasificationNathan Weiland, Nick Means, and Bryan MorrealeNETL 2010 Workshop on Multiphase Flow SciencePittsburgh, PA, May 4-6, 2010

2

Background

Coal• National resource

with over 200 years supply

• Currently supplies over 50% of US power– Potential to supply

transportation fuels

Biomass• Carbon neutral• Renewable

-1000

-500

0

500

1000

1500

2000

Life

cycl

e G

HG

Foo

tprin

t [lb

GH

G/M

Wh]

Reducing GHG Footprint with Carbon Capture & Biomass

Coal Only

Coal + Biomass& 90% CCS

($2)

$0 $6 $6 $9

$22

$131

147%

-5% -12%-20%

-33%

-63%

-150%

-100%

-50%

0%

50%

100%

150%

200%

no CCS CCS CCS ATR CBTL8 CBTL15 CBTL30 BTL no CCS

$(20)

$-

$20

$40

$60

$80

$100

$120

$140

emis

sion

s re

lativ

e to

bas

elin

e

cost increase per barrel

cost relative to CTL+CCS % reduction from petroleum baseline

NETL Office of Systems, Analysis and Planning

3

Influence of Biomass Addition

O2

CO2

Biomass

Coal

O2

H2O

CO2 to Sequestration

H2OO2

CO2

CHne-

n=2 for transportationn=4 for natural gas

• Prolong coal reserves

• Reduce carbon foot print of gasification process

4

How Significant of a Resource is Biomass?

Mbrandt, A., A Geographic Perspective on the Current Biomass Resource Availability in the United States. 2005, National Renewable Energy Laboratory: Golden CO.Net Generation by Energy Source: Total (All Sectors). : http://www.eia.doe.gov/cneaf/electricity/epm/table1_1.html

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Where is Biomass Located in the US?

325-423 MDTA

Mbrandt, A., A Geographic Perspective on the Current Biomass Resource Availability in the United States. 2005, National Renewable Energy Laboratory: Golden CO.Net Generation by Energy Source: Total (All Sectors). : http://www.eia.doe.gov/cneaf/electricity/epm/table1_1.html

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Goals

Programmatic Goal• Coal & Power Systems: Sequester 90% of the carbon from coal

with minimal impact to the cost of power, fuels and chemicals• Advanced Gasification: Develop innovative gasification

technologies that provides a clean, stable, secure and affordable energy supply to meet the nations growing demand

Project Goal• Promote the utilization of biomass in coal gasification

processes for the production of power, fuels and chemicals by applying computational and experimental approaches ranging from fundamental through demonstration scales

This study supports the expansion of DOE’s R&D portfolio with an intent to meet “zero emission” standards

www.netl.doe.gov/technologies/coalpower/gasification

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Gasification Process

Processing /Feeding

Processing /Feeding

Gasification SyngasCleaning

SyngasProcessing

Gasification

Power

Fuels

Chemicals

Solid / Liquid

Syngas

Solid / Liquid

Solid / Liquid

CO2 Management

OperatingT (oC)

Biomass waste Coal Gas Petcoke Petroleum

Entrained 1400-1600 0 41 22 9 60Fluidized bed 900-1050 10 3Moving bed 425-650 3 7

Brown et al., Assessment of Technologies for Co-converting Coal and Biomass to a Clean Syngas, NETL Task ReportCiferno et al., Benchmarking Biomass Gasification Technologies for Fuels, Chemicals and Hydrogen Production, NETL Task Report

*Feed class by plant

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Co-Gasification Technical Uncertainties

• Raw Biomass– Material Variability (season, location, etc)– Transportation (Energy Density)– Storage (Degradation)– Biomass Structure and Mechanical Properties – Grindability

• Pressurized Dry Feed – Technology is not mature– Particle Size & Shape factors critical for specific feeder types

• Gasifier Performance– Reaction Kinetics– Material Interactions– Product Effects– Models not Developed/Validated

• Process Optimization

NETL Office of Systems, Analysis and Planning

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Co-gasification Program Strategy

Task 1Prep/Feed

Task 2Gasifier

Modeling

Task 3Gasifier RXN

Chemistry

Task 4Gasifier

Materials

Energy, Flow& Material

Information

GasifierPerformance

Systems Analysis(OSAP)

• Lifecycle• Economics• Logistics

Material Life

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Objective #2

Objective #1

Task 3. Gasifier Reaction Chemistry Approach

Raw / TreatedBiomassCOAL

Blend

MovingBed

EntrainedFlow

KineticData

ProductProperties

Task 2Modeling

Task 4Gasifier

Materials

Task 1Prep/Feed

Task 3

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Gasifier Reaction Chemistry

Heat Rate

Slow Fast

Higman and van der Burgt, (2003)

Pyrolysis

CharGasification

Pyrolysis&

Gasification

Heat Rate

Slow Fast

Higman and van der Burgt, (2003)

Pyrolysis

CharGasification

Pyrolysis&

Gasification

• Objective #1– Identify the influence of co-

feeding coal-biomass mixtures on kinetics

• Heat rate and pressure• Feed mixtures• Feed preparation method• Particle size

– Conditions consistent with Sasol gasification

• Moving bed• 1000oC• Pyrolytic conditions

• Feedstock Selection– Coal types: Illinois #6,

Wyodak, Powder RiverBasin, North DakotaLignite

– Biomass types: Mixedhardwood, wheat straw, corn stover, switchgrassDDG, algae

260 538 816 1093 1649oC

Drying

Gasification

Devolitization

Combustion

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Sample Specifications

• Illinois #6– Ground &

sieved• -18 +50 mesh• 279 to

1000µm

• Switchgrass– Pelletized– Ground &

sieved• -16 +50 mesh• 279 to

1190µm

0

10

20

30

40

50

60

70

80

Wei

ght %

, Dry

Bas

is

Switchgrass

ILL #6

Proximate Analysis Ultimate Analysis

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Coal / Biomass Feed Stock Ash Analysis

0

10

20

30

40

50

60

Al Ba Ca Fe K Mg Mn Na P Si Sr Ti

Tota

l Am

ount

of A

sh W

t %

Switch Grass

Illinois#6 Coal

Mn x10-2 Sr x10-2

Ti x10-1Ba x10-2

P x10-1

• Analysis done by ICP OES

• Ash analysis of raw, as received samples

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Experimental Setup • Feed mixtures

– 100, 85, 70, 50, 0 (wt% coal)

• Operations– Semi-batch– 1 gram loading– T to 1000oC– P to 1000 psi– On-line MS-Quad gas analysis– Ex-situ tar, char and gas

analysis

Hopper

Ar

O2

H2

Air

CO2

H2O

Heat Heat

Condenser

MSQuad

Mixer

BagSample

Quartz liner

Quartz frit

0 50 100 150

Inte

nsity

Test Time (Seconds)

H2HeCCH4CH4H2OCOCO2

15

Coal

-15

-10

-5

0

5

10

15

400 500 600 700 800 900 1000Temperature [oC]

Posi

tion

[cm

]

100 sccm1000 sccm5000 sccm

Gasifier Process Development

•Reactor Temperature–~1 cm isothermal zone, +/- 2 C–Independent of flow–Initial 10 C drop in temperature at drop time

•Reactor Flow–Minimize side reactions–Maximize gas sampling sensitivity

–Optimal reactor flow is greater than ~1.5slpm for pure coal and biomass

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0 1000 2000 3000 4000 5000 6000 7000

Diluent Flow [sccm]

Indi

visu

al P

rodu

ct [g

]

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

Total Products [g]

m H2m CO2m COm CH4m H2OTotal Product Mass

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Influence of Co-Feeding on Gaseous Products

0

0 1 2 3 4C

O

Time [min]

0

0 1 2 3 4

CO

2

Time [min]

0

0 1 2 3 4

H2O

Time [min]

0

0 1 2 3 4

H2

Time [min]

0

0 1 2 3 4

CH

4Time [min]

Switch Grass

50wt% SG/ILL

30wt% SG/ILL

15wt% SG/ILL

Illionis#6 Coal

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Influence of Co-Feeding on Gaseous Products

0.0

0 20 40 60 80 100 120

Tota

l Gas

Pro

duct

s

Time [s]

Data

Model

Switch Grass (SG)

Illinois#6 Coal (ILL)

50wt% SG / ILL

30wt% SG / ILL

15wt% SG / ILL

Model = (xbiomass)*(mbiomass) + (xcoal)*(mcoal)

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0.000

0.005

0.010

0.015

0.020

0.025

0.030

0.035

0.040

0.045

0.050

0 10 20 30 40 50 60 70 80 90 100

Rate

of T

otal

Gas

Pro

duce

d [g

/ s

]

Weight Percent Switchgrass in Feed [Balance Illinois #6 Coal]

Measured Rate

Predicted Rate

Influence of Co-Feeding on Gaseous Products

45x

2.0x

1.5x

1.4x

(SG + Ill#6, 900oC, 30 psi, Ar)

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0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0 1000 2000 3000 4000 5000 6000 7000

Diluent Flow [sccm]

Indi

visu

al P

rodu

ct [g

]

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

Total Products [g]

m H2m CO2m COm CH4m H2OTotal Product Mass

Co-Gasification Product Characterization

• Objective #2– Identify the influence of co-

feeding coal-biomass mixtures on solid, liquid and gaseous products

• Syngas composition• Catalytic effects• Alkaline biomass ash effects

on syngas cleanup• Conditions consistent with

Sasol gasification technology– Fixed bed, Lurgi gasifier– 1000oC– Pyrolytic conditions

• Same feedstocks– Illinios #6 Coal– Ground, Pelletized Switchgrass

20

0

10

20

30

40

50

60

70

80

0 20 40 60 80 100

Prod

uct W

t%

Weight % Biomass

Gas

Char

Tar

Qualitative Product Distribution Trends

21

Influence of Co-Feed on Gas Composition (Pyrolysis at 900oC)

Illinois # 6 Coal

Switch Grass

50% Coal50% Biomass

ALL

Coal

Biomass

22

Influence of Co-Feed on Tar Composition (Pyrolysis at 900oC)

0

0 10 20 30 40 50 60

Time [min]

Res

pons

e

ALL

Coal

Illinois # 6 Coal

Switch Grass

50% Coal50% Biomass

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Influence of Co-Feed on Char Composition

0.0

0.1

1.0

10.0

100.0

Al Ba Ca Fe K Mg Mn Na Sr Ti

Wt %

in A

sh

Illinois#6 Coal As Rec'd

Illinois#6 Coal - Char

85% ILL - 15% SG

70% ILL - 30% SG

50% ILL - 50% SG

Switch Grass - Char

Switch Grass As Rec'd

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Summary• Established a test protocol for quantifying the influence of

biomass on coal gasification reactions• Preliminary results suggests that co-feeding Ill#6 and SG has

– Minimal deviation from production trend• More coal yields more ash and tar, less syngas

– Reaction rates appear to deviate from pure samples• Not simply release of volatile gases

– Coal - biomass char interactions (possibly catalytic)– Coal - volatile gas product interactions

– Gas and liquids products:• Coal rich feeds had more aromatics and S-containing compounds• Biomass rich feeds had O-containing compounds, chlorinated HC’s,

and low HC’s– Solid Products

• Ill#6 had higher transition metal content (Fe, Al, Ti)• SG had higher alkali content (K, Ca, Mg)• Biomass char – coal interactions (catalytic effect)• Some mineral species volatilizing from ash (K, Mg, Na)

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Future Work• Relocating and upgrading reactor• Develop kinetic devolitization

model– Varying temperature & pressure– Species, feed ratio, particle size– Investigate catalytic effect

• Complete devolitization evaluation of 2nd coal-biomass combination

• Investigate effects of biomass feed preparation methods

• Initiate testing protocol with mixed feed gases (gasification)– H2O, O2, CO2

• Coal types– Illinois #6– Wyodak– Powder River Basin– North Dakota Lignite

• Biomass types– Mixed hardwood– Wheat straw– Corn stover– Switchgrass– DDG with corn fiber– Algae

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Anticipated Benefits

• Provide fundamental gasification reaction chemistry required to address co-gasification uncertainties as well as optimize co-gasification models

• Develop a thorough understanding of gas, liquid and solid products developed from co-gasification reactions which will enable the development and optimization of construction materials and downstream processing

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Acknowledgments

NETL Research FacultyDr. Goetz Veser

Dr. Sittichai NatesakhawatUniversity of Pittsburgh

U.S. DOE - NETLDr. Bryan Morreale

Dr. Dirk LinkDr. Bret Howard

Dr. Charles Taylor

NETL Site Support ContractorsNick Means, URS

Paul Zandhuis, URSBrian Kail, URS

Dr. Mike Ciocco, URSDr. Sonia Hammache, URS

Technical staff, URS

This technical effort was performed in support of the National Energy Technology Laboratory’s on-going research in coal and biomass conversion technologies under the RDS contract DE-AC26-04NT41817 and URS contract DE-FE0004000.

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