Linking Laboratory Scale Gasification Measurements with Coal Performance in a Pilot Scale Gasifier

David Harris & D. RobertsCSIRO Energy TechnologyCCT 2009, Dresden18 May, 2009

J. Lamp & F. FrischSiemens Gasification & Fuel Technology, Freiberg

CCT 2009, Dresden

Outline

•

Pilot and laboratory testing of a reference suite of four well-

characterised coals•

Coal gasification performance issues•

Laboratory characterisation of coal gasification behaviour•

Volatile yield, char structure, char reactivity•

Slag viscosity and flow behaviour•

Application of fundamentals through ‘simple’

conversion models•

Pilot scale gasification test program•

Validating and applying the fundamentals•

Identifying the key coal selection and operating criteria•

Impact of coal properties on plant operation and performance•

Guidance for future coal gasification and syngas

R&D program

CCT 2009, Dresden

Gasification Research Program

•

High pressure, high temperature coal conversion measurements

•

Effects of reaction conditions and coal type•

Development of coal test procedures •

Fundamental investigations of coal gasification reactions

•

Reaction mechanisms and kinetics, model development.

•

Slag formation and flow for entrained-flow gasification

•

Syngas cleaning & processing•

Gas separation (H2

/CO2

)•

Technology performance models

Improve the understanding of coal performance in gasification technologies, supporting:

•

Use of Australian coals in new technologies•

Implementation of low emissions coal technologies in Australia.

CCT 2009, Dresden

flux

O2

CO/CO2

slag

CO2 and H2

O

CO + H2

Interrogating the Gasification Process

Gas Analysis

Pilot testing –

generating real gasification conditionsto test overall coal performance

PEFR: Investigating gasificationbehaviour under controlled andmeasurable conditions

High pressure wire-mesh reactor: Pyrolysis behaviour under high pressuresand high heating ratesChar gasification kinetics: high pressureTGA and fixed-bed reactorsSlag viscosity measurements

•

Laboratory-scale investigations to understand the important processes that combine to gasify

coal under practical conditions.

•

Larger-scale testing to ‘recombine’

process steps under process conditions

•

Predictive capability of gasification behaviour

•

Assess coals for specific gasification technologies

•

Develop operating strategies•

Troubleshooting gasification processes

•

Support technology development

CCT 2009, Dresden

0

20

40

60

80

100

120

0 50 100 150 200 250

Stoichiometry (%)

Carb

on C

onve

rsio

n (%

) CRC274CRC298CRC299CRC281CRC252CRC263CRC358

1400°C, 2.5% O2

Evaluation of Coal Gasification Behaviour

•

Optimum range of stoichiometries

for ‘gasification efficiency’. Trade-off to achieve maximum conversion.

•

Higher volatile coals (generally) achieve greater conversion than lower volatile coals•

Exception is CRC299 –

indicates that char reactivity is also significant (agrees with

TGA testing of coal suite)

•

Higher temperature differentiates

coals on the basis of different char reactivities•

Effect of coal type also reflects extent of conversion•

Conversion drives syngas

composition (via gas phase equilibria)

0

20

40

60

80

0 50 100 150 200 250Stoichiometry (%)

CRC274CRC298CRC281CRC299CRC252CRC263CRC358

1400°C, 2.5% O2

Gas

ifica

tion

‘effi

cien

cy’(

%)

CCT 2009, Dresden

CO2

/char reaction rate at ‘high’

temperature

CRC252

Residence time (s)

0.0 0.5 1.0 1.5 2.0

Cha

r con

vers

ion

(%)

0

20

40

60

80

100

CRC272

Residence time (s)

0.0 0.5 1.0 1.5 2.0

CRC281

Residence time (s)

0.0 0.5 1.0 1.5 2.0 2.5 3.0

1273 K1373 K1473 K1573 K1673 K

•

PEFR operated with controlled gas atmospheres (fix PCO2

, Ptotal

, T)•

Char produced in-situ •

Conversion measured along length of reactor (t ≤

3s)•

Char samples taken for thorough analysis•

Morphology, structure, surface area, pore size distribution…•

‘Intrinsic’

reactivity•

Density and particle size

Semi anthraciteBituminous Sub bit, high vol

20 bar total pressure, 5 bar CO2

partial pressure

CCT 2009, Dresden

Char/CO2

reaction rates: understanding chemical and physical factors

•

First of a kind data for high pressure char/CO2

and char/steam reactions (PEFR)•

Thiele modulus and effectiveness factor based on observed particle morphology

•

‘effective’

diffusion length•

Low T ‘intrinsic’

and high T ‘practical’

rate data can be reconciled when a detailed understanding of char structure is available

•

Still difficult to resolve burnoff

effects•

Challenge to extend to multiple reactants1/Temperature (1/K)

0.0004 0.0005 0.0006 0.0007 0.0008 0.0009 0.0010

ln(s

peci

fic ra

te (g

g-1

s-1

))

-12

-10

-8

-6

-4

-2

0

2

particle sizewall thickness

PEFR dataFBR data

Char 1 Char 2 Char 3

E M Hodge, D G Roberts, D J Harris and J F Stubington*. Am. Chem. Soc. Div. Fuel Chem. Prep. 54(1) 2009

CCT 2009, Dresden

Gasification modelling

•

Model needed for interrogation and application of measurements•

Integration of fundamentals with system and technology models•

relationships with international programs, pilot and demo plant operators•

Australia has no pilot or commercial scale gasification plant•

Collaboration is essential to apply knowledge and to ‘validate’

outcomes•

First pilot scale test program conducted August 2007 (Siemens, Germany)

0.00.10.20.30.40.50.60.70.80.9

0.0 0.5 1.0 1.5 2.0 2.5

Distance from reactor top (m)

Rea

ctio

n ra

te (k

g/kg

/s)

0

10

20

30

40

50

60

70

80

Car

bon

conv

ersi

on (%

)

C+O2 C+CO2 C+H2O Carbon conversion

Gas T

Particle flow

CCT 2009, Dresden

Pilot Scale Gasification Testing of Australian Coals

•

Sponsored by •

ACARP, Xstrata Coal, WA Coal Futures Group, Verve Energy, Delta Electricity, CCSD, CSIRO

•

Siemens gasification test facility, Freiberg, Germany

CCT 2009, Dresden

Siemens Gasification Test Facility

•

5MWth gasification facility•

Dry or slurry feed•

Cooling screen walls•

Includes syngas quench, gas analysis and sampling points

•

Slag, solids and process water sampling

•

Gas treatment, S removal systems•

Expert operations team!

CCT 2009, Dresden

Test Program

•

Four Australian Coals•

Selected to cover a wide range of coal properties•

Rank, petrography, volatile yield, char structure•

Semi-anthracite, high vol bituminous, high vol sub-bit, high moisture ‘lignitic’•

Well characterised through laboratory gasification research program•

Attempted to keep ash fusion/flow temperatures low

•

Five Gasification Tests•

One ‘pre-test’•

One test program on each coal•

Each test consisted of 2-3 ‘balance phases’, where the coal and O2

feeds were steady and measurements and samples could be taken

•

Two sets of conditions:•

‘optimal’

gasification conditions for each specific coal, and•

comparison of coals under common ‘reference’

conditions

CCT 2009, Dresden

Coal Sample Analyses

CRC701 CRC702 CRC703 CRC703 (fluxed)

CRC704

Moisture (% ar) 6.4* 1.3 0.9 0.9 2.3**

Ash (% ar) 5.6 8.7 9.6 10.9 11.7

VM (% ar) 36.2 34.4 7.2 8.7 44.1

FC (% ar) 51.8 55.6 82.3 79.5 41.9

C (% daf) 76.1 86.3 92.8 93.5 79.0

H (% daf) 4.5 5.2 3.7 4.0 5.8

N (% daf) 1.5 1.9 1.9 1.9 1.0

S (% daf) 1.1 1.2 0.7 0.7 0.3

O (% daf) 16.8 5.3 0.9 0.0 14.1

AFT flow (reducing) °C 1290 1310 1540 1430 1440

Specific Energy (HHV), MJ/kg as rec

25.7 30.6 32.1 31.1 28.2

* CRC701 dried prior to tests (initially 25%), **CRC704 dried from 13.4%

CCT 2009, Dresden

Estimated slag viscosity for test coals

•

Viscosity calculated prior to tests from models based on experimental database for a wide range of Australian coals

•

CRC704 ash composition indicated slag flow T and viscosity in upper end of desired range

•

CRC703 required fluxing –

supplied sample indicated excessively high viscosity•

Viscosity of gasifier and lab slags examined after pilot test program

0

20

40

60

80

100

120

140

1200 1300 1400 1500 1600

Temperature, oC

Visc

osity

Pa

s

CRC702CRC703fluxedCRC703CRC704

25Pas

CCT 2009, Dresden

Typical Data: Reactor Parameters (single run)Diagramm NKV102 - reactor parameter

0.0

100.0

200.0

300.0

400.0

500.0

600.0

700.0

800.0

900.0

1000.0

1100.0

1200.0

1300.0

8:45 9:45 10:45 11:45 12:45 13:45 14:45 15:45 16:450.0

0.5

1.0

1.5

2.0

2.5

3.0

Y left = dP reactor/quench [mbar]: RAA11CP004 Y left = Flow rawgas calculated [Nm³/h]: calculated Y left = F O2 main burner [Nm3/h]: REH12CF003 Y right = GPC: heat to cooling screen [GJ/h]: GPC00CQ003

Select

coalstart

coalstop

Balance Phase 1: 10:15-13:00

Evaluation Period: 12:30-13:00

Balance Phase 2: 13:45-15:30 Balance Phase 3: 16:00-17:15

Evaluation Period: 14:15-14:45 Evaluation Period: 16:00-16:30

O:C = 1.38 O:C = 1.37O:C = 1.32

Syngas flow

Heat loss

•

Decreasing O:C ratio decreases temperature (indicated by decreased heat loss)•

Affects conversion, gas quality, slag formation and flow

O2

CCT 2009, Dresden

Typical Data: Gas Composition (major species)

•

Decreasing O:C ratio increases CO and H2

production (decreases CO2

production)

Diagramm NKV102 - rawgas analysis online

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

45.0

50.0

55.0

60.0

65.0

70.0

8:45 9:45 10:45 11:45 12:45 13:45 14:45 15:45 16:450.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

Y le ft = Q H2 [Vol%]: RKC30CQ 001

Y le ft = Q CO 2 [Vol%]: RKC30CQ 002 Y left = Q CO [Vol%]: RKC30CQ005

Y right = Q CH4 [Vol%]: RKC30CQ003

Select

coalstart

coalstop

Balance Phase 1: 10:15-13:00

Evaluation Period: 12:30-13:00

Balance Phase 2: 13:45-15:30 Balance Phase 3: 16:00-17:15

Evaluation Period: 14:15-14:45 Evaluation Period: 16:00-16:30

O:C = 1.38 O:C = 1.37 O:C = 1.32

CO

CO2

H2

CCT 2009, Dresden

Technical Scale Data: PEFR Gas Analyses

•

Consistent with pilot scale data, decreasing O:C ratio decreases

CO2

and increases CO and H2

.

CO

H2

CO2

O2

CCT 2009, Dresden

Initial Results –

Runs Summary

Test and Balance Phase Coal Temp. Ave (°C) X (%) O:C

(mol:mol)CGE (%)

NKV100 BP1 CRC701 1616 98.5 1.27 67.5

NKV100 BP2 CRC701 1532 96.2 1.20 72.7

NKV101 BP1 CRC701 1621 97.3 1.24 75.4

NKV101 BP2 CRC701 1462 97.0 1.10 77.8

NKV102 BP1 CRC702 1576 96.5 1.37 66.7

NKV102 BP2 CRC702 1620 100.6 1.38 73.4

NKV102 BP3 CRC702 1240 99.8 1.32 73.0

NKV103 BP1 CRC703 1453 93.8 1.26 67.8

NKV103 BP2 CRC703 1502 96.8 1.33 71.5

NKV103 BP3 CRC703 1368 94.8 1.20 74.3

NKV104 BP1 CRC704 1718 93.3 1.47 56.0

NKV104 BP2 CRC704 1725 97.0 1.42 63.3

NKV104 BP3 CRC704 1679 96.0 1.37 66.6

*

CCT 2009, Dresden

0

20

40

60

80

100

0.0 0.5 1.0 1.5 2.0 2.5 3.0

Residence Time (s)

Con

vers

ion

(%)

.PEFR and Pilot data

0

20

40

60

80

100

0 50 100 150 200

Stoichiometry (%)

Gas

ifica

tion

Effi

cien

cy (%

)

0

20

40

60

80

Cold

Gas

effi

cien

cy -

Tria

ls (%

)

CRC704CRC701CRC702CRC703CRC701CRC702CRC703CRC704

.

•

Effects of stoichiometry on gasification performance demonstrated using PEFR experiments

•

‘Peak’

at just under 1:1 stoich

then decrease with increasing O:C (for HV coals). •

Results of pilot scale tests consistent•

Decrease in GE as O:C increases above 1:1•

Smaller differences between coals because gasifier is ‘optimised’

for maximum conversion (PEFR data includes effects of reactivity differences)

CCT 2009, Dresden

Relative gasification propensity

•

Attempt to decouple operating conditions and coal gasification behaviour•

Pilot tests require higher O:C stoichiometry•

‘normalise’

for additional CO2

•

Relative ranking consistent between PEFR and Pilot tests•

PEFR results indicative of need for more or less aggressive gasification conditions•

Slag requirements may over-ride gasification reaction requirements (eg CRC704)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

110 120 130 140 150 160

Stoichiometry (%)

Tria

ls 'I

ndex

'

CRC704

CRC702

CRC701CRC703

(b)

.

0

20

40

60

80

100

0 50 100 150 200

Stoichiometry (%)

'Gas

ifica

tion

Effic

ienc

y' (%

)

CRC704CRC701CRC702CRC703

.

(a)

CCT 2009, Dresden

Slag analysis –

composition, leaching, viscosity…

CRC701

CRC703

CRC702

CRC704

* Semi-anthracite, fluxed

CCT 2009, Dresden

Measured Slag Viscosity

CRC702

0

20

40

60

80

100

1200 1300 1400 1500 1600

Temperature, oC

Visc

osity

, Pa

s

predicted

laboratory slag

trial slag

CRC703 fluxed

01020

3040506070

8090

100

1200 1300 1400 1500 1600

Temperature, oC

Visc

osity

, Pa

s

predicted

laboratory slag

trial slag

CRC704

0102030405060708090

100

1200 1300 1400 1500 1600

Temperature, oC

Vis

cosi

ty, P

a s

predictedlaboratory slag 1laboratory slag 2trial slag

CRC701

0102030405060708090

100

1200 1300 1400 1500 1600

Temperature, oC

Visc

osity

, Pa

s

laboratory slagtrial slag

CCT 2009, Dresden

http://www.propubs.com/pictures/gsslagpou

r2.gif

Summary•

First comparative pilot scale performance data for Australian coals•

Laboratory scale measurements provide ‘transportable’

performance data for different coal types

•

Volatile yield, reaction kinetics, char structure, conversion…•

Slag viscosity and flow behaviour •

Data and knowledge applicable through reactor and flow models•

Entrained flow reactor (PEFR) demonstrates differences in coal behaviour

•

indicates strategies and operating parameters to achieve satisfactory conversion in practical systems.

•

Pilot tests demonstrate clear relevance of lab/PEFR measurements•

Design and operating strategies for ‘difficult’

coals identified and tested at lab and pilot scale

•

Clear linkage of results and data between lab and pilot scale essential for application and validation of research program (eg

coal testing, syngas

quality etc) •

Detailed evaluation of coal, char, slag, water samples from pilot tests is providing unique and valuable insights for reference coal suite

Thank You Contact: David HarrisPhone: +61 7 3327 4617Email: David.Harris@csiro.au

CCT 2009, Dresden

Gasification based low emissions energy

Source: US DoE Oak Ridge Laboratories

Gasification R&D focus

CCT 2009, Dresden

High Pressure Entrained Flow Reactor (PEFR)

•

Entrained-flow reactor•

20 bar pressure, 1500°C wall temperature•

Coal feed rate of 1-5 kg/hr •

Gas mixtures of O2

, CO2

, H2

O and N2•

Adjustable sampling probe -

char and gas samples collected at different residence times (0.5-3s)

Gas Analysis

Feeder

Preheating and mixing

Three-section reaction zone

Water quench

Sampling probe and gas analysis

CCT 2009, Dresden

0

1

2

3

4

5

6

7

0 20 40 60 80 100

Carbon Conversion (%)

Equi

libriu

m G

as C

ompo

sitio

n (m

ol%

)Gasification conversion drives gas phase composition

CRC274 – 1300°C, 5%O2VM (daf) = 32.6%

CO

H2

CO2

steam

O2

Points = measuredLines = eqbm

CCT 2009, Dresden

Reconciliation of ‘low’

and ‘high’

T rate data

(a) CRC252

0.0005 0.0006 0.0007 0.0008 0.0009

-12

-10

-8

-6

-4

-2

0

2(b) CRC272

0.0005 0.0006 0.0007 0.0008 0.0009

ln (g

asifi

catio

n ra

te, g

g-1

s-1

)

(c) CRC281

1/Temperature (K-1)

0.0005 0.0006 0.0007 0.0008 0.0009 0.0010

~900°C ~900°C~900°C

~1400°C ~1400°C~1400°C

•

Consistent trends observed in rate, activation energy•

Low and high T data measured independently•

Apparent discontinuity remains between high and low T data sets•

High rank coal most affected •

Greater variation in char types, pore structure, surface area

CCT 2009, Dresden

CRC252

1/temperature (1/K)

0.0004 0.0005 0.0006 0.0007 0.0008 0.0009

ln (g

asifi

catio

n ra

te (g

g-1

s-1

))

-12

-10

-8

-6

-4

-2

0

2

1373 K1473 K 1573 K 1673 K

low temp specific rate1273 K

Group I Group II Group III

low temp specific rate

combined morphology

CRC272

1/temperature (1/K)

0.0004 0.0005 0.0006 0.0007 0.0008 0.0009

High pressure char gasification rates

CRC252

1/temperature (1/K)

0.0005 0.0006 0.0007 0.0008 0.0009

ln (g

asifi

catio

n ra

te (g

m-2 s

-1))

-18

-16

-14

-12

-10

-8

-6

-4

-2

0

low temp intrinsic rateintrinsic rate

Group IGroup II Group III combined

CRC272

1/temperature (1/K)

0.0005 0.0006 0.0007 0.0008 0.0009

CCT 2009, Dresden

Slag Viscosity Testing

•

Slag Viscosity•

25 Pa s is the accepted maximum viscosity at the slag tap for successful operation

•

Flux addition required if viscosity is too high•

Temperature of Critical Viscosity•

Slag becomes heterogeneous•

Trouble-free tapping of slag not possible

10

20

30

40

1300 1350 1400 1450 1500 1550

50

Maxim um for Slag Tappability

Tcv

Visc

osity

Pa.

sTem perature 0C

100/0 Ash/CaCO3

100/10 Ash/CaCO3

100/20 Ash/CaCO3

CCT 2009, Dresden

Why Pilot Testing?

•

Goals of the Laboratory and Technical Scale work to date have been specific:

•

Fundamental understanding of gasification process•

Flexible and transportable data applicable to a range of gasification technologies

•

Identification of ‘indices’

for coal assessment and gasifier optimisation & design

•

This leaves some unanswered questions:•

Are the scientific issues identified and understood to date significant at pilot scale (and full scale) coal gasification?

•

Can the models under development be used to target specific gasification technologies?

•

Do the tools and techniques developed accurately reflect variations in coal performance under ‘real’

gasification conditions?