5th International Freiberg Conference on IGCC & XtL Technologies - IFC2012

Pressurized CO2-gasification of coal

Marek Sciazkoa, Tomasz Chmielniaka,

Grzegorz Tomaszewicza, Martyna Tomaszewiczb

a Institute for Chemical Processing of Coal, Zabrze, Poland

b Faculty of Chemistry, Silesian University of Technology, Gliwice, Poland

23 May 2012 Leipzig, Germany

1

Scope of presentation

1. A few words about the Institute for Chemical Processing of Coal

2. Clean Coal Technology Center

3. Coal gasification with CO2 as a co-gasifing agent

4. Factors influencing the Boudouard reaction

5. Process thermodynamic modeling

6. Coal samples and experimental setup

7. Results of preliminary studies on kinetics of Boudouard reaction

and evaluation of kinetic constants, and the latter dependencies

from selected coal parameters

8. Conclusions

9. Acknowledgments

2/23

Research Institute

57 years of experience

238 employees

184 research and scientific staff

4 accredited laboratories

Institute for Chemical Processing of Coal (IChPW)

3/23

Heat & power production

Fuels

IChPW R&D – main activities

4/23

Clean Coal Technology Center

5/23

C + CO2 ↔ 2CO + 172 kJ/mol C + O2 → CO2 - 396 kJ/mol C + H2O ↔ CO + H2 + 131 kJ/mol C + ½O2 → CO - 110 kJ/mol Effects:

• utilization of CO2 removed from fossil fuels conversion,

• increase of process yield and improvement of syngas synthesis economy,

• reduction of fossil fuels consumption in syngas production,

• decrease of oxygen consumption (CO2 as oxidation agent).

circulating fluidized bed reactor

Crude syngas

Char

Fossil fuel

CO2 O2, H2O

Coal gasification with CO2 as a co-gsifing agent

6/23

Factors influencing the Boudouard reaction

The reactivity of coal chars towards CO2 is influenced by: • coal rank, • pyrolysis conditions (heating rate, holding time, and final

temperature), • pressure, • ash content, • content of inorganic constituents likely to catalyze oxygen

exchange reactions, • surface morphology, • pore structure, • particle size.

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Thermodynamic modeling

8/23

60

65

70

75

80

85

90

95

0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40

Col

d ga

s ef

ficie

ncy,

%

CO2/C, molar ratio

80090010001300

Thermodynamic modeling - summary

Parameter Unit Value Remarks

Consumption of fuel Mg/h 100 Janina (sub-bituminous coal)

Production

Methanol synthesis Mg/h 45.3 -

Power generation (oxy-fuel

combustion MW 75 net

Power generation (total) MW 36 net, including total system

needs

Efficiencies

Cold gas efficiency

(gasification) % 90.4 -

Methanol synthesis % 57.2 gross

Power generation (oxy-fuel

combustion) % 30.2 LHV, compression

9/23

hvCb

Coal samples

Coal

Turów Piast

Bogdanka Janina

LigB SubA

SubB

10/23

Heating rate = 5 K/min

Coal mine KWB

„Turów” KWK

„Piast” ZG

„Janina” LW

„Bogdanka” Proximate analysis Wt

ar, % 44.2 14.4 21.3 11.6 Wad, % 3.9 4.7 12 4.2 Ad, % 8.1 21.1 12.0 16.7 Vdaf, % 59.14 39.10 39.56 37.68 Ultimate analysis CT

ad, % 62.3 59.3 60.4 66.2 HT

ad, % 5.48 3.83 3.46 4.16 Nad, % 0.61 0.91 0.94 1.35 ST

ad, % 1.02 1.09 1.22 1.34 SA

ad, % 0.28 0.20 0.05 0.04 SC

ad, % 0.74 0.89 1.17 1.30 Od

ad, % 19.17 10.27 11.23 6.79 Clad, % 0.009 0.399 0.131 0.026 Chemical analysis of ash SiO2, % 32.7 51.42 46.48 51.85 Al2O3, % 24.5 27.03 28.42 32.87 Fe2O3, % 11.4 7.23 9.59 5.26 CaO, % 4.10 2.71 3.33 1.15 MgO, % 6.24 3.30 2.76 1.27 TiO2, % 1.86 1.04 1.11 1.44 Na2O, % 6.76 2.06 3.49 0.56 K2O, % NDA 2.40 2.46 3.34 Petrographic composition and related V, % 73 54 65 68 L, % 17 10 10 9 I, % 6 23 18 6 R, % 0.23 0.58 0.44 0.64

Parent coals: Pyrolysis:

Coal mine KWB

„Turów” KWK „Piast” ZG „Janina”

LW „Bogdanka”

Proximate analysis Wad. % 2.2 1.1 1 0.7 Ad. % 13.7 25.4 13.6 25.8 Vdaf. % 0.77 0.47 0.82 0.47 Ultimate analysis CT

ad. % 84.8 72.9 83.9 72.2 HT

ad. % 0.28 0.32 0.34 0.34 Nad. % 0.98 1.08 0.91 1.09 CT

ad. % 83.07 73.2 84.4 70.1 HT

ad. % 0.31 0.32 0.35 0.29 Nad. % 1.05 0.98 1.04 1.13 Oad. % 2.05 0.98 0.85 0.75

Chars:

Fuel samples

Time, min

Tem

pera

ture

, °C

11/23

Char Sample mass – 3 g (ar) Grain size – 13.15 mm CO2 flow – 66 g/h Temperature – 950°C Pressure – 1, 10 and 20 bar

Schematic diagram of the experimental setup

12/23

The calculation procedure and analized models

44

32)(

28

16)(

44

3222

tmtmmout

CO

out

CO

in

CO

28

12)(

44

12)()(

44

1222

tmtmtmmout

CO

out

COC

in

CO

)(14

3)( tmtm

out

COC

m

(t)dtmtX

t

C

0

Xkdt

dXVM

1 tkXVM 1ln

3

2

1 Xkdt

dXGM

tkXGM 3

1

113

XXdt

dX 1ln1)1(

2

0

0014

S

L

tkXRPM 11ln1

2

11ln2

2

max

X

L0 – initial pore length related to volume of sample, S0 - initial surface area related to volume of sample, ε0 – initial porosity of sample.

1) Volumetric Model, VM:

2) Grain Model, GM:

3) Random Pore Model, RPM:

The rates of char conversion were calculated by balancing the amounts of carbon, and oxygen entering, and exiting the reaction system as a function of mass flowrate:

Combining of equations above yields an expression for an instantaneous mass consumption rate:

The relationship between the fractional conversion of carbon in the char (X) and time (t):

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0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 1200 2400 3600 4800 6000 7200 8400

Car

bo

n c

on

vers

ion

, X

, -

Time, t, s

Piast Char

1 bar

10 bar

20 bar

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 1200 2400 3600 4800 6000 7200 8400

Car

bo

n c

on

vers

ion

, X

, -

Time, t, s

Janina Char

1 bar

10 bar

20 bar

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 2400 4800 7200 9600 12000 14400

Car

bo

n c

on

vers

ion

, X

, -

Time, t ,s

Bogdanka Char

1 bar

10 bar

20 bar

Conversion vs. time data

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 600 1200 1800 2400 3000 3600 4200

Car

bo

n c

on

vers

ion

, X

, -

Czas, t, s

Turów Char

1 bar

10 bar

20 bar

y = 0.0006x r² = 0.8254

y = 0.0006x r² = 0.8222

y = 0.0007x r² = 0.8196

0

1

2

3

4

5

6

7

0 1200 2400 3600 4800 6000 7200 8400

-ln

(1-X

)

Time, t, s

Piast Char

1 bar

10 bar

20 bar

y = 0.000645x r² = 0.8802

y = 0.000655x r² = 0.8151

y = 0.000658x r² = 0.7855

0

1

2

3

4

5

6

7

8

9

0 1200 2400 3600 4800 6000 7200 8400

-ln

(1-X

)

Time, t, s

Janina Char

1 bar

10 bar

20 bar

y = 0.000225x r² = 0.7646

y = 0.000457x r² = 0.8489

y = 0.000382x r² = 0.7625

0

1

2

3

4

5

6

7

8

0 2400 4800 7200 9600 12000 14400

-ln

(1-X

)

Time, t, s

Bogdanka Char

1 bar

10 bar

20 bar

Volumetric Model

y = 0.001161x r² = 0.7835 y = 0.001180x

r² = 0.7884

y = 0.001127x r² = 0.7885

0

1

2

3

4

5

6

7

8

0 600 1200 1800 2400 3000 3600 4200

-ln

(1-X

)

Czas, t, s

Turów Char

1 bar

10 bar

20 bar

y = 0.000322x r² = 0.9724

y = 0.000377x r² = 0.9656

y = 0.000405x r² = 0.9741

0

0.5

1

1.5

2

2.5

3

0 1200 2400 3600 4800 6000 7200 8400

3(1

-(1

-X)1

/3)

Time, t, s

Piast Char

1 bar

10 bar

20 bar

y = 0.000331x r² = 0.9934

y = 0.000374x r² = 0.9761

y = 0.000383x r² = 0.9658

0

0.5

1

1.5

2

2.5

3

3.5

0 1200 2400 3600 4800 6000 7200 8400

3(1

-(1

-X)1/

3)

Time, t, s

Janina Char

1 bar

10 bar

20 bar

y = 0.000254x r² = 0.9861

y = 0.000262x r² = 0.9720

y = 0.000260x r² = 0.9688

0

0.5

1

1.5

2

2.5

3

0 1200 2400 3600 4800 6000 7200 8400 9600 10800

3(1

-(1

-X)1

/3)

Time, t, s

Bogdanka Char

1 bar

10 bar

20 bar

Grain Model

y = 0.000640x R² = 0.9722

y = 0.000663x R² = 0.9725

y = 0.000660x R² = 0.9770

0

0.5

1

1.5

2

2.5

3

0 600 1200 1800 2400 3000 3600 4200

3(1

-(1

-X)1

/3)

Time, t, s

Turów Char

1 bar

10 bar

20 bar

y = 0.000077x r² = 0.9963

y = 0.000155x r² = 0.9941 y = 0.000125x

r² = 0.9907

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0 1200 2400 3600 4800 6000 7200 8400

Time, t, s

Bogdanka Char

1 bar

10 bar

20 bar

y = 0.000146x r² = 0.9995

y = 0.000166x r² = 0.9983

y = 0.000223x r² = 0.9922

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0 600 1200 1800 2400 3000 3600 4200 4800

Time, t, s

Piast Char

1 bar

10 bar

20 bar

y = 0.000249x r² = 0.9896

y = 0.000280x r² = 0.9674

y = 0.000276x r² = 0.9511

0

0.5

1

1.5

2

2.5

0 1200 2400 3600 4800 6000 7200 8400Time, t, s

Janina Char

1 bar

10 bar

20 bar

Random Pore Model

y = 0.000382x r² = 0.9958

y = 0.000411x r² = 0.9929

y = 0.000420x R² = 0.99294r

0

0.2

0.4

0.6

0.8

1

1.2

0 600 1200 1800 2400 3000 3600

Czas, t, s

1 bar

10 bar

20 bar

kGM kRPM Pressure, bar 1 10 20 1 10 20 Bogdanka 0.000147 0.000257 0.000238 0.000077 0.000155 0.000125 Janina 0.000331 0.000374 0.000383 0.000249 0.000280 0.000276 Piast 0.000322 0.000377 0.000405 0.000146 0.000167 0.000234 Turów 0.00064 0.000663 0.000660 0.00039 0.000411 0.000420

Odiff/C, - CI, % R, % Bogdanka 0.103 3.663 0.64 Janina 0.186 5.734 0.44 Piast 0.173 7.817 0.58 Turów 0.308 9.877 0.23

Next step: to find a correlation between estimated kinetic

coefficients and properties of parent coals.

Results - summary

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%,100

100

322

2232

OAlSiO

ONaOKOFeMgOCaOA

VCI d

daf

y = 0.0024x - 0.0001 r² = 0.9979

y = 0.0022x + 3E-06 r² = 0.9752

y = 0.002x + 3E-05 R² = 0.9874

0

0.0001

0.0002

0.0003

0.0004

0.0005

0.0006

0.0007

0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4

k GM

, 1/s

Odiff/C, -

1 bar

10 bar

20 bar

y = 0.0015x - 8E-05 r² = 0.9372

y = 0.0013x + 2E-06 r² = 0.8736

y = 0.0012x + 2E-05 r² = 0.9575

0

0.0001

0.0002

0.0003

0.0004

0.0005

0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4

k RP

M, 1

/s

Odiff/C, -

1 bar

10 bar

20 bar

y = 7E-05x - 0.0001 R² = 0.8557

y = 6E-05x + 2E-05 R² = 0.8308

y = 6E-05x + 9E-07 R² = 0.8973

0

0.0001

0.0002

0.0003

0.0004

0.0005

0.0006

0.0007

3 4 5 6 7 8 9 10

k GM

, 1/s

Catalytic index, %

1 bar

10 bar

20 bar

y = 4E-05x - 6E-05 R² = 0.6268

y = 3E-05x + 4E-05 R² = 0.5004

y = 4E-05x - 1E-05 R² = 0.7933

0

0.0001

0.0002

0.0003

0.0004

0.0005

3 4 5 6 7 8 9 10

k RP

M, 1

/s

Catalytic index, %

1 bar

10 bar

20 bar

y = -0.0011x + 0.0009 R² = 0.9083

y = -0.0009x + 0.0008 R² = 0.8962

y = -0.0009x + 0.0008 R² = 0.8645

0

0.0001

0.0002

0.0003

0.0004

0.0005

0.0006

0.0007

0.2 0.3 0.4 0.5 0.6 0.7 0.8

k GM

, 1/s

Ro, %

1 bar

10 bar

20 bar

y = -0.0007x + 0.0006 R² = 0.9924

y = -0.0007x + 0.0006 R² = 0.9903

y = -0.0007x + 0.0006 R² = 0.9422

0

0.0001

0.0002

0.0003

0.0004

0.0005

0.2 0.3 0.4 0.5 0.6 0.7 0.8

k RP

M, 1

/s

Ro, %

1 bar

10 bar

20 bar

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Conclusions (1)

1. Results of performed thermodynamic calculations indicate that the addition of CO2 has beneficial effects, leading to a 30% decrease in coal consumption at the same carbon monoxide capacity as a conventional gasification system without CO2 addition.

2. Additionally, due to the oxidative role of CO2 as a gasifying agent, oxygen demand is also decreased. According to thermodynamic calculations, an increase in process pressure strongly diminishes the CO capacity.

3. In contrast to the thermodynamic calculations, our experimental data revealed that increasing the CO2 pressure leads to a higher reaction rate for medium-rank coal chars and low-rank lignite coal char, resulting in higher efficiency for carbon monoxide production.

4. The pressure influences the reactivity more strongly in the range of 1 to 10 bar; further pressure increases affect the rate almost insignificantly.

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Conclusions (2)

5. The observed behavior representing the changes in the degree of carbon conversion during gasification are satisfactorily described by the grain model and random pore model.

6. The char derived from the Turów lignite proved to be much more reactive under the applied pressure conditions than the chars from the Janina, Piast and Bogdanka coals.

7. The very satisfactory values of the determination coefficients indicate a strong relationship between coal parameters and the reaction rate. The derived relationships suggest a great possibility for the development of semi-empirical rate expressions that can be used for the prediction of coal char behavior during pressurized gasification.

21/23

Acknowledgments

The research results presented herein were obtained during the course of the project “Development of coal gasification technology for high-efficiency production of fuels and energy”, Task No. 3 of the Strategic Program for Research and Development: "Advanced energy generation technologies" funded by the Polish National Center for Research and Development.

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INSTITUTE FOR CHEMICAL PROCESSING OF COAL Zamkowa 1 Str. 41803 Zabrze, POLAND

Phone: +48 32 271 00 41 Fax: +48 32 271 08 09

E-mail: office@ichpw.zabrze.pl Web: www.ichpw.zabrze.pl

THANK YOU FOR YOUR KIND ATTENTION

23/23