Benjamin M. Statler College of Engineering and Mineral Resources 1

Coal and biomass bubbling fluidized bed gasifier - design and operation

Ali Sivri1

Cosmin Dumitrescu1

Amoolya Lalsare2

John Hu2

1 Center for Alternative Fuels Engines and Emissions (CAFEE)Department of Mechanical & Aerospace Engineering, West Virginia University

2 Department of Chemical Engineering, West Virginia University

NETL 2019 Workshop On Multiphase Flow Science

Benjamin M. Statler College of Engineering and Mineral Resources 2

• Motivation

• Objectives

• Experimental setup

• Material characteristics

• Results

• Conclusions

• Future work

Outline

Benjamin M. Statler College of Engineering and Mineral Resources 3

• Efficient use of conventional and alternative energy resources

• Bubbling fluidized bed gasifier (BFBG) can convert biomass and

coal into value-added chemicals and gaseous fuels for

transportation or electricity generation

• Understanding the parameters that affect the fluidization

hydrodynamics

• Collect experimental data representative of optimum conditions

and use it to develop numerical simulations

Motivation

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• Design and manufacture a BFBG that will help MFIX code

development

• Investigate parameters that affect fluidization hydrodynamics

• Investigate coal and biomass and coal gasification

o Efficiency

o Product composition

• Collect data for model development

Objectives

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Experimental setup - Cold flow visualization and measurements

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Expansion tanks

Heat exchanger

Screw feeder

Feeder control unit

Furnace

Screw feeder Reactor Furnace

Micro GC

Experimental setup – BFBG at high temperatures

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Particle geometry

- Particle size and sphericity distribution affects the efficiency and product gas composition

- Important for correct process simulation

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Material Average of

particle size

(µm)

Average of

Sphericity

Hardwood 432 0.564

Coal 361 0.847

Glass beads 279 0.933

Sand 368 0.863

Table 1. Material size and sphericity analysis

Material Characteristics

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Glass beads Sand

Close-up of bed material geometry

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Close-up of fuel material geometry

Biomass Coal

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0

0.5

1

1.5

2

2.5

0 0.05 0.1 0.15 0.2

ΔP

[K

Pa]

Uair [m/s]

Glass beads

100 g

200 g

300 g

0

0.5

1

1.5

2

2.5

0 0.05 0.1 0.15 0.2

ΔP

[K

Pa]

Uair [m/s]

Glass beads and coal

100 g

200 g

300 g

Results: Pressure drop across the bed - cold flow

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0

0.5

1

1.5

2

2.5

3

0 0.05 0.1 0.15 0.2

ΔP

[K

Pa]

Uair [m/s]

Glass beads and wood

100 g

200 g

300 g

0

0.5

1

1.5

2

2.5

3

0 0.05 0.1 0.15 0.2

ΔP

[K

Pa]

Uair [m/s]

Sand and wood

100 g

200 g

300 g

Results: Pressure drop across the bed - cold flow

Benjamin M. Statler College of Engineering and Mineral Resources 13

Movie 2. Sand and coal

0

0.5

1

1.5

2

2.5

3

0 0.05 0.1 0.15 0.2

ΔP

[K

Pa]

Uair [m/s]

Sand

100 g

200 g

300 g

0

0.5

1

1.5

2

2.5

3

3.5

0 0.05 0.1 0.15 0.2

ΔP

[K

Pa]

Uair [m/s]

Sand and coal

100 g

200 g

300 g

Results: Pressure drop across the bed - cold flow

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Results: Effect of temperature on ΔP across the distributor plate

0 1 2 3 4 5 6 7 8 9 10

0.06

0.12

0.18

0.24

0.30

0.36

0.42

0.48

0.54

0.60

Average reaction temperatures [oC]

26

138

323

539

716

805

ΔP

(1

-2)

[PS

I]

Qair [SLM]

Distributor plate (DP) pressure drop40 micron grade1/8 “ thickness

- Operating temperature affects the pressure drop across the distributor plate

- Temperature will affect bubbling characteristics

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0

0.4

0.8

1.2

1.6

2

0 0.04 0.08 0.12 0.16 0.2

ΔP

[K

Pa

]

Uair [m/s]

Sand 200 g

Ambient200400600800

oC

Results: Pressure drop across the bed – hot gasifier

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0

0.4

0.8

1.2

1.6

2

2.4

2.8

3.2

3.6

0 0.04 0.08 0.12 0.16 0.2

ΔP

[K

Pa

]

Uair [m/s]

Sand 300 g

Ambient200400600800

oC

Results: Pressure drop across the bed – hot gasifier

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1st Run 2nd Run

10

20

30

40

50

60

44

.9

56

.3

35

.4

24

.9

17

.8

14

1.7

3 4.4

4

0.1

51

0.3

58

0 0

Coal steam gasification – Product composition

H2:CO = 3.2

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1 min 2 min 3 min 4 min 5 min

10

20

30

40

50

60

70

37

.8

66

.1

43

38

.2

64

19

.1

16

.8

14

14

.2

14

.6

20

.5

2.6

4

32

.7

34

.5

10

.6

18

.7

14

.3

8.7

2

10

9.9

6

3.8

9

0.0

66

1.6

1

3.0

3

0.8

12

0.0

56

0 0.0

25

0.0

50

4

0.0

30

3

Coal steam gasification – Product composition

H2:CO = 3.2

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2 gr 1.6 gr 1.5 gr 0.8 gr 1.5 gr

10

20

30

40

50

605

7.2

1

63

.15

49

.85

52

.89

51

.32

23

.00

19

.54

31

.99

29

.55

28

.95

9.4

4

8.4

0

8.1

5

4.6

8

6.7

7

9.1

7

7.8

3

8.9

4 11

.84

11

.58

1.2

9

1.0

8

1.0

7

1.0

4

1.3

9

0.0

0

0.0

0

0.0

0

0.0

0

0.0

0

• Reverse water gas shift reaction affects product composition

Biomass gasification – product composition

H2:CO = 0.5

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Conclusions

• Binary mixtures with lower voidage ratio and higher

bulk densities improve fluidization

• Operating temperature also effects the pressure drop

through the distributor plate

• Preliminary results of coal and coal gasification are promising

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Future work

• Improve the feeding system (continuous)

• Improve the product gas sampling (continuous)

• Improve measurement (multiple locations)

• Improve temperature control

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Acknowledgements

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Thank you

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BFBG experimental setup

Expansion tanks

Heat exchanger

Screw feeder

Feeder control unit

Furnace

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BFBG experimental setup

Bubbling fluidized bed reactor system.P: Pressure sensor, T: Temperaturesensor, 1: Nitrogen tank, 2:Compressed air tank, 3: Expansiontanks, 4: Bed reactor, 5: Furnace, 6:Feeding system gas flow line, 7:Feeding point, 8: Output gas line, 9:Gas sampling valve, 10: Bed reactorcooling gas line, 11: Bed reactorfluidization gas line.

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0

0.1

0.2

0.3

0.4

0.5

0.6

26 226 426 626 826

Pre

ssu

re D

rop

(1-2

) [P

SI]

Temperature [oC]

1 SLM

2 SLM

3 SLM

4 SLM

5 SLM

6 SLM

7 SLM

8 SLM

9 SLM

10 SLM

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0

0.1

0.2

0.3

0.4

0.5

0.6

0 1 2 3 4 5 6 7 8 9 10

Pre

ssu

re D

rop

(1-2

) [P

SI]

Q [SLM]

100

200

300

400

500

600

700

800

[oC]

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Table 2. Material elemental analysis

MaterialMoisture,

(%)Volatile, (%) Ash, (%) Nitrogen, (%) Carbon, (%) Hydrogen, (%) Oxygen, (%)

Biomass

(Hardwood) 7.16 75.65 0.32 0.9 45.25 4.65 49.2

Coal

(Pittsburgh #8) 1.3 34 10.6 1.6 85.6 5.8 7

Benjamin M. Statler College of Engineering and Mineral Resources 29

• Design, build and operate a laboratory-scale bubbling fluidized bed gasifier

(BFBG) using biomass (hardwood) and coal as feedstocks.

• Analyze the fluidization hydrodynamics of binary mixtures with biomass and

coal as feedstocks by using a laboratory-scale BFBG cold-flow rig (CFR).

• Analyze the effect of temperature on fluidization hydrodynamics at actual

experimental conditions up to 800 oC.

• Perform biomass and coal gasification operations in accordance with the data

obtained from cold flow experiments and analyze the product gas compositions.

• Provide high quality data for NETL Multiphase Flow Group for modeling.

Objectives

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0

0.2

0.4

0.6

0.8

1

1.2

0 0.04 0.08 0.12 0.16 0.2

ΔP

[K

Pa

]

Uair [m/s]

Sand 100 g

Ambient200400600800

oC

BFBG fluidization hydrodynamics analysis

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Material(Mixtures)

Bulk density (g/cc)

Voidage(%)

Glass beads + coal 1.61 35

Glass beads + hardwood 1.43 38

Sand + coal 1.56 41

Sand + hardwood 1.38 44

Table 2. Material bulk density and voidage analysis