Modeling and Simulation of Size Reduction of Modeling and Simulation of Size Reduction of FuelsFuels

in Circulating Fluidized Bed Combustor by in Circulating Fluidized Bed Combustor by Considering Attrition and FragmentationConsidering Attrition and Fragmentation

ByBy

Natthapong Ngampradit, Ph.D.Natthapong Ngampradit, Ph.D.

14 Dec 2006

OutlineOutline

Research objectivesResearch objectives• Experiments on fuels comminutionExperiments on fuels comminution• CFBC simulation on industrial-scaleCFBC simulation on industrial-scale• CFBC simulation on laboratory-scaleCFBC simulation on laboratory-scale• ConclusionsConclusions

Research Objectives Research Objectives Research Objectives Research Objectives

• Study the comminution of local coal and Study the comminution of local coal and biomass.biomass.

• Model and simulate a circulating Model and simulate a circulating fluidized bed combustor by including fluidized bed combustor by including

the condition of the comminution effect. the condition of the comminution effect.

Experiments on Fuels ComminutionExperiments on Fuels ComminutionExperiments on Fuels ComminutionExperiments on Fuels Comminution

Experimental Experimental proceduresproceduresExperimental Experimental proceduresprocedures

• Blank studyBlank study• Attrition studyAttrition study• Primary fragmentation studyPrimary fragmentation study• Secondary fragmentation Secondary fragmentation

studystudy

ApparatusApparatusApparatusApparatus

Figure 1Figure 1 ApparatusApparatusFigure 1Figure 1 ApparatusApparatus

Table 1Table 1 Operating conditions of the CFB reactor Operating conditions of the CFB reactor forfor communition testcommunition test

Table 1Table 1 Operating conditions of the CFB reactor Operating conditions of the CFB reactor forfor communition testcommunition test

Experimental variables

Operating conditions

Fluidizing gas Operating pressure Bed temperature Superficial gas velocity Bed material Mass of coal sample Size of coal

N2 and air Atmosphere 850 oC 4 m/s Sand (dpavg = 500 m) 4 g 2–3 mm

29

Figure 2Figure 2 The PSD of sand from blank study at 850 The PSD of sand from blank study at 850 ooC, C, 1 atm 1 atm

that analyzed by particle size laser that analyzed by particle size laser analyzer.analyzer.

Figure 2Figure 2 The PSD of sand from blank study at 850 The PSD of sand from blank study at 850 ooC, C, 1 atm 1 atm

that analyzed by particle size laser that analyzed by particle size laser analyzer.analyzer.

BlankBlank StudyStudyBlankBlank StudyStudy

AttritionAttrition StudyStudyAttritionAttrition StudyStudy

Figure 3Figure 3 Mixed particle between coal and sand after Mixed particle between coal and sand after attritionattrition study at the ambient environment by CCD study at the ambient environment by CCD camera.camera.

Figure 3Figure 3 Mixed particle between coal and sand after Mixed particle between coal and sand after attritionattrition study at the ambient environment by CCD study at the ambient environment by CCD camera.camera.

Particle diameter (mm)

4.00

3.75

3.50

3.25

3.00

2.75

2.50

2.25

2.00

1.75

1.50

Num

ber

of

part

icle

s

50

40

30

20

10

0

Std. Dev = .28

Mean = 2.63

N = 220.0045

8

31

3737

33

42

13

3

Particle diameter (mm)

3.88

3.75

3.63

3.50

3.38

3.25

3.13

3.00

2.88

2.75

2.63

2.50

2.38

2.25

2.13

2.00

Num

ber

of p

arti

cles

12

10

8

6

4

2

0

Std. Dev = .33

Mean = 2.68

N = 42.001

2

1

4

3

7

11

4

7

11

(a) (b)

Figure 4Figure 4 PSD from Image Pro Plus: PSD from Image Pro Plus: (a) raw material, (b) attrition particles(a) raw material, (b) attrition particlesFigure 4Figure 4 PSD from Image Pro Plus: PSD from Image Pro Plus: (a) raw material, (b) attrition particles(a) raw material, (b) attrition particles

Figure 5Figure 5 The PSD of mixed particles from attrition study at The PSD of mixed particles from attrition study at ambient environment that analyzed by particle sizeambient environment that analyzed by particle size laser analyzer compare with blank study at 850 laser analyzer compare with blank study at 850 ooC, C, 1 atm.1 atm.

Figure 5Figure 5 The PSD of mixed particles from attrition study at The PSD of mixed particles from attrition study at ambient environment that analyzed by particle sizeambient environment that analyzed by particle size laser analyzer compare with blank study at 850 laser analyzer compare with blank study at 850 ooC, C, 1 atm.1 atm.

Primary FragmentationPrimary Fragmentation StudyStudyPrimary FragmentationPrimary Fragmentation StudyStudy

Figure 6Figure 6 Mixed particle between coal and sand after primary Mixed particle between coal and sand after primary fragmentation study at 850 fragmentation study at 850 ooC, 1 atm with NC, 1 atm with N22 as the as the

fluidizing gas by CCD camera.fluidizing gas by CCD camera.

Figure 6Figure 6 Mixed particle between coal and sand after primary Mixed particle between coal and sand after primary fragmentation study at 850 fragmentation study at 850 ooC, 1 atm with NC, 1 atm with N22 as the as the

fluidizing gas by CCD camera.fluidizing gas by CCD camera.

Particle diameter (mm)

Num

ber

of

part

icle

s

100

80

60

40

20

0

Std. Dev = .33

Mean = 2.08

N = 462.005611

21

47

71

94

73

48

36

22

810

Figure 7Figure 7 PSD from Image Pro Plus of primary PSD from Image Pro Plus of primary fragmentationfragmentation particles.particles.

Figure 7Figure 7 PSD from Image Pro Plus of primary PSD from Image Pro Plus of primary fragmentationfragmentation particles.particles.

Figure 8Figure 8 Compare the cumulative fraction between the Compare the cumulative fraction between the experimentexperiment of primary fragmentation at 850 of primary fragmentation at 850 ooC, 1 atm with NC, 1 atm with N22

as the as the fluidizing gas and the model prediction for large fluidizing gas and the model prediction for large particles.particles.

Figure 8Figure 8 Compare the cumulative fraction between the Compare the cumulative fraction between the experimentexperiment of primary fragmentation at 850 of primary fragmentation at 850 ooC, 1 atm with NC, 1 atm with N22

as the as the fluidizing gas and the model prediction for large fluidizing gas and the model prediction for large particles.particles.

Mean diameter

2.12E-3

Figure 9Figure 9 The PSD of mixed particles from primary The PSD of mixed particles from primary fragmentationfragmentation study at 850 study at 850 ooC, 1 atm with NC, 1 atm with N22 as the fluidizing as the fluidizing

gas thatgas that analyzed by particle size laser analyzer analyzed by particle size laser analyzer compare with compare with blank study at 850 blank study at 850 ooC, 1 atm. C, 1 atm.

Figure 9Figure 9 The PSD of mixed particles from primary The PSD of mixed particles from primary fragmentationfragmentation study at 850 study at 850 ooC, 1 atm with NC, 1 atm with N22 as the fluidizing as the fluidizing

gas thatgas that analyzed by particle size laser analyzer analyzed by particle size laser analyzer compare with compare with blank study at 850 blank study at 850 ooC, 1 atm. C, 1 atm.

Figure 10Figure 10 Compare the cumulative fraction between Compare the cumulative fraction between the the experiment of primary fragmentation at 850 experiment of primary fragmentation at 850 ooC, C, 1 atm1 atm with Nwith N22 as the fluidizing gas and the model as the fluidizing gas and the model

prediction prediction for small particles.for small particles.

Figure 10Figure 10 Compare the cumulative fraction between Compare the cumulative fraction between the the experiment of primary fragmentation at 850 experiment of primary fragmentation at 850 ooC, C, 1 atm1 atm with Nwith N22 as the fluidizing gas and the model as the fluidizing gas and the model

prediction prediction for small particles.for small particles.

Mean diameter

627

Secondary FragmentationSecondary Fragmentation StudyStudySecondary FragmentationSecondary Fragmentation StudyStudy

Figure 11Figure 11 Mixed particle between coal and sand after Mixed particle between coal and sand after secondary secondary fragmentation study at 850 fragmentation study at 850 ooC, 1 atm with C, 1 atm with air as the air as the fluidizing gas.fluidizing gas.

Figure 11Figure 11 Mixed particle between coal and sand after Mixed particle between coal and sand after secondary secondary fragmentation study at 850 fragmentation study at 850 ooC, 1 atm with C, 1 atm with air as the air as the fluidizing gas.fluidizing gas.

Figure 12Figure 12 The PSD of mixed particles from The PSD of mixed particles from secondary secondary fragmentation study at 850 fragmentation study at 850 ooC, 1 atm with air as C, 1 atm with air as the the fluidizing gas that analyzed by particle size fluidizing gas that analyzed by particle size laser laser analyzer compare with blank study at 850 analyzer compare with blank study at 850 ooC, 1 C, 1 atm.atm.

Figure 12Figure 12 The PSD of mixed particles from The PSD of mixed particles from secondary secondary fragmentation study at 850 fragmentation study at 850 ooC, 1 atm with air as C, 1 atm with air as the the fluidizing gas that analyzed by particle size fluidizing gas that analyzed by particle size laser laser analyzer compare with blank study at 850 analyzer compare with blank study at 850 ooC, 1 C, 1 atm.atm.

Figure 13Figure 13 Cumulative fraction of secondary Cumulative fraction of secondary fragmentation at fragmentation at 850 850 ooC, 1 atm with air as the fluidizing gas. C, 1 atm with air as the fluidizing gas.

Figure 13Figure 13 Cumulative fraction of secondary Cumulative fraction of secondary fragmentation at fragmentation at 850 850 ooC, 1 atm with air as the fluidizing gas. C, 1 atm with air as the fluidizing gas.

Unburnt carbon

Ash

Figure 14Figure 14 Compare the cumulative fraction Compare the cumulative fraction between the between the experiment of secondary fragmentation at 850 experiment of secondary fragmentation at 850 ooC, 1 atm C, 1 atm with air as the fluidizing gas and the model with air as the fluidizing gas and the model prediction for prediction for ash particles.ash particles.

Figure 14Figure 14 Compare the cumulative fraction Compare the cumulative fraction between the between the experiment of secondary fragmentation at 850 experiment of secondary fragmentation at 850 ooC, 1 atm C, 1 atm with air as the fluidizing gas and the model with air as the fluidizing gas and the model prediction for prediction for ash particles.ash particles.

Mean diameter

25

Figure 15Figure 15 Compare the cumulative fraction Compare the cumulative fraction between the between the experiment of secondary fragmentation at 850 experiment of secondary fragmentation at 850 ooC, 1 atm C, 1 atm with air as the fluidizing gas and the model with air as the fluidizing gas and the model prediction for prediction for unburnt particles. unburnt particles.

Figure 15Figure 15 Compare the cumulative fraction Compare the cumulative fraction between the between the experiment of secondary fragmentation at 850 experiment of secondary fragmentation at 850 ooC, 1 atm C, 1 atm with air as the fluidizing gas and the model with air as the fluidizing gas and the model prediction for prediction for unburnt particles. unburnt particles.

Mean diameter

295

BiomassBiomass StudyStudyBiomassBiomass StudyStudy

(a)

(b)

Figure 16Figure 16 The PSD of bagasse-sand particles at 850 The PSD of bagasse-sand particles at 850 ooC, 1 C, 1 atm by atm by particle size laser analyzer: (a) primary particle size laser analyzer: (a) primary fragmentation, fragmentation, NN22 as the fluidizing gas (b) secondary as the fluidizing gas (b) secondary

fragmentation, fragmentation, air as the fluidizing gas.air as the fluidizing gas.

Figure 16Figure 16 The PSD of bagasse-sand particles at 850 The PSD of bagasse-sand particles at 850 ooC, 1 C, 1 atm by atm by particle size laser analyzer: (a) primary particle size laser analyzer: (a) primary fragmentation, fragmentation, NN22 as the fluidizing gas (b) secondary as the fluidizing gas (b) secondary

fragmentation, fragmentation, air as the fluidizing gas.air as the fluidizing gas.

CFBC Simulation on Industrial-scaleCFBC Simulation on Industrial-scaleCFBC Simulation on Industrial-scaleCFBC Simulation on Industrial-scale

21.8

4 m

21.8

4 m

6.026 m6.026 m

1.703 m1.703 m

1.5 m1.5 m

Primary airPrimary air

Secondary airSecondary air

Tertiary airTertiary air

6.02

6 m

6.02

6 m

Figure17Figure17 Dimension of combustor.Dimension of combustor. Figure17Figure17 Dimension of combustor.Dimension of combustor.

Dimension of CFBCDimension of CFBCDimension of CFBCDimension of CFBC

Assumptions of the reaction modelAssumptions of the reaction modelAssumptions of the reaction modelAssumptions of the reaction model

• The fuel, limestone, and primary air were fed at the bottom of The fuel, limestone, and primary air were fed at the bottom of the CFBC with a uniform temperature.the CFBC with a uniform temperature.

• The simulated combustor was a rectangular column with the The simulated combustor was a rectangular column with the surface area of 36.31 msurface area of 36.31 m22 and the height of 21.84 m. In the and the height of 21.84 m. In the

proposed model, the secondary and tertiary air was fed into proposed model, the secondary and tertiary air was fed into the combustor at the specified height.the combustor at the specified height.

• The combustion of volatile matters occurred instantaneously The combustion of volatile matters occurred instantaneously at the bottom of the combustor.at the bottom of the combustor.

• Char combustion occurred slowly after volatile matters were Char combustion occurred slowly after volatile matters were combusted.combusted.

• Gas and fuel particle temperatures were equal to the bed Gas and fuel particle temperatures were equal to the bed temperatures varying with respect to the height of the riser.temperatures varying with respect to the height of the riser.

• The attrition of the char particles was neglected.The attrition of the char particles was neglected.• All steps of the reactions were calculated with an isothermal at All steps of the reactions were calculated with an isothermal at

850 850 OOC.C.

RYIELD

RSTOIC

RYIELD RYIELD RYIELD RYIELD

LIGNITE PITH SLUDGE F4 F5

AIR1 LIME

RCSTR

RCSTR

RSTOIC

RSTOICAIR2

RCSTR

RCSTR

RSTOIC

RCSTR

AIR3

RCSTR

RSTOIC

RCSTR

RCSTR

RSTOIC

HEXT

CYCLONE

WATER STEAM

FLUE GAS

SSPLIT

BOTTOM

FLY ASH

LOWER REGION

UPPER REGION

1st Interval

2nd Interval

3rd Interval

Figure 18Figure 18 Simulation diagram for the CFBCSimulation diagram for the CFBCFigure 18Figure 18 Simulation diagram for the CFBCSimulation diagram for the CFBC

Simulation ProceduresSimulation Procedures [Sotudeh-Gharebaagh 1998]

• Devolatilization and volatilize Devolatilization and volatilize combustioncombustion

• Char combustionChar combustion

• NONOxx formation formation

• SOSO22 absorption absorption

Results and discussionResults and discussionResults and discussionResults and discussion

The model was used to simulate the operation of a CFBC The model was used to simulate the operation of a CFBC that produced 110 tons/hr of steam at 510 that produced 110 tons/hr of steam at 510 ooC and 110 barg. C and 110 barg.

The fuels to be considered were both of single fuels and The fuels to be considered were both of single fuels and mixed fuels. In case of a single fuel, 4 kg/s of lignite were mixed fuels. In case of a single fuel, 4 kg/s of lignite were fed into the combustor. The other case, the mixed fuels fed into the combustor. The other case, the mixed fuels

between lignite and biomass were considered. Each between lignite and biomass were considered. Each simulation of the mixtures was decreased the lignite flow simulation of the mixtures was decreased the lignite flow rate by 10 %. The flow rate of biomass was increased for rate by 10 %. The flow rate of biomass was increased for

keeping the constant of amount of carbon.keeping the constant of amount of carbon.

0

1

2

3

4

4.0:0.0 3.6:0.6 3.2:1.1 2.8:1.7 2.4:2.2 2.0:2.8Ratio of lignite:bagasse

(a)

Rat

e of

rea

ctio

n *

10-2

(K

mol

/s)

Lower Upper1 Upper2 Upper3

0

1

2

3

4

4.0:0.0 3.6:0.6 3.2:1.1 2.8:1.7 2.4:2.3 2.0:2.8Ratio of lignite:bark

(b)

Rat

e of

rea

ctio

n *

10-2

(K

mol

/s)

Lower Upper1 Upper2 Upper3

0

1

2

3

4

4.0:0.0 3.6:0.7 3.2:1.3 2.8:2.1 2.4:2.7 2.0:3.3

Ratio of lignite:sludge(c)

Rat

e of

rea

ctio

n *

10-2

(K

mol

/s)

Lower Upper1 Upper2 Upper3

Figure 20Figure 20 Rates of the combustion of lignite in mixed fuels for Rates of the combustion of lignite in mixed fuels for each regioneach region

in the CFBC: (a) lignite&bagasse (b) lignite&bark (c) in the CFBC: (a) lignite&bagasse (b) lignite&bark (c) lignite&sludgelignite&sludge

0

1

2

3

4

5

3.6:0.6 3.2:1.1 2.8:1.7 2.4:2.2 2.0:2.8Ratio of lignite:bagasse

(a)

Rat

e of

rea

ctio

n *

10-2

(K

mol

/s)

Lower Upper1 Upper2 Upper3

0

1

2

3

4

5

3.6:0.6 3.2:1.1 2.8:1.7 2.4:2.3 2.0:2.8

Ratio of lignite:bark(b)

Rat

e of

rea

ctio

n *

10-2

(Km

ol/s

)

Lower Upper1 Upper2 Upper3

0

1

2

3

4

5

3.6:0.7 3.2:1.3 2.8:2.0 2.4:2.7 2.0:3.3Ratio of lignite:sludge

(c)

Rat

e of

rea

ctio

n *

10-2

(Km

ol/s

)

Lower Upper1 Upper2 Upper3

Figure 21Figure 21 Rates of the combustion of biomass in mixed fuels for each Rates of the combustion of biomass in mixed fuels for each regionregion in the CFBC: (a) lignite&bagasse (b) lignite&bark (c) in the CFBC: (a) lignite&bagasse (b) lignite&bark (c) lignite&sludgelignite&sludge

0

20

40

60

80

100

4.0:0.0 3.6:0.6 3.2:1.1 2.8:1.7 2.4:2.2 2.0:2.8Ratio of lignite:bagasse

(a)

Am

ount

of

flue

gas

(%

)

0

2000

4000

6000

8000

10000

Am

ount

of

flue

gas

(pp

m)

O2 (%) N2 (%) CO (%)

CO2 (%) H2O(%) SO2 (ppm)NO (ppm) N2O (ppm)

0

20

40

60

80

100

4.0:0.0 3.6:0.6 3.2:1.1 2.8:1.7 2.4:2.3 2.0:2.8Ratio of lignite:bark

(b)

Am

ount

of

flue

gas

(%

)

0

2000

4000

6000

8000

10000

Am

ount

of

flue

gas

(pp

m)

O2 (%) N2 (%) CO (%)

CO2 (%) H2O(%) SO2 (ppm)No (ppm) N2O (ppm)

0

20

40

60

80

100

4.0:0.0 3.6:0.7 3.2:1.3 2.8:2.1 2.4:2.7 2.0:3.3Ratio of lignite:sludge

(c)

Am

ount

of

flue

gas

(%

)

0

2000

4000

6000

8000

10000

Am

ount

of

flue

gas

(pp

m)

O2 (%) N2 (%) CO (%)

CO2 (%) H2O(%) SO2 (ppm)NO (ppm) N2O (ppm)

Figure 22Figure 22 The composition of flue gas for different kind of mixed The composition of flue gas for different kind of mixed fuel:fuel: (a) lignite&bagasse (b) lignite&bark (c) lignite&sludge(a) lignite&bagasse (b) lignite&bark (c) lignite&sludge

CFBC Simulation on Laboratory-CFBC Simulation on Laboratory-scalescaleCFBC Simulation on Laboratory-CFBC Simulation on Laboratory-scalescale

Assumptions of the reaction modelAssumptions of the reaction modelAssumptions of the reaction modelAssumptions of the reaction model

• The fuel, limestone, and primary air were fed at the The fuel, limestone, and primary air were fed at the bottom of the CFBC with a uniform temperature.bottom of the CFBC with a uniform temperature.

• The combustion of volatile matters occurred The combustion of volatile matters occurred instantaneously at the bottom of the combustor.instantaneously at the bottom of the combustor.

• Char combustion occurred slowly after volatile matters Char combustion occurred slowly after volatile matters were combusted.were combusted.

• Gas and fuel particle temperatures were equal to the Gas and fuel particle temperatures were equal to the bed temperatures varying with respect to the height of bed temperatures varying with respect to the height of

the riser.the riser.• All steps of the reactions were calculated with an All steps of the reactions were calculated with an

isothermal at 850 isothermal at 850 OOC.C.

B1 (RYIELD)

B2 (RSTOIC)

B9 (RCSTR)

B3 (RCSTR)

B4 (RCSTR)

B5 (RCSTR)

B6 (RCSTR)

B7 (CYCLONE) B8 (SSPLIT)

LIGNITE

FLUE GAS

RESOLID

FLY ASH

BOTTOM

AIR

Figure 23Figure 23 Simulation diagram for the laboratory scale CFBC.Simulation diagram for the laboratory scale CFBC. Figure 23Figure 23 Simulation diagram for the laboratory scale CFBC.Simulation diagram for the laboratory scale CFBC.

Weibull distribution for the primary fragmentationWeibull distribution for the primary fragmentationWeibull distribution for the primary fragmentationWeibull distribution for the primary fragmentation

Large particlesLarge particles

Small particlesSmall particles

5.7

31013.2exp1

l

M

lM

T

5.7

627exp1

l

M

lM

T

Results and discussionResults and discussionResults and discussionResults and discussion

In the simulation, coal and air was fed at 0.015 g∙sIn the simulation, coal and air was fed at 0.015 g∙s-1-1 and 7 l∙minand 7 l∙min-1-1. The simulations were divided in two . The simulations were divided in two cases. The first case, the PSD was calculated only by cases. The first case, the PSD was calculated only by the shrinking core model subroutine. The second the shrinking core model subroutine. The second one, the primary fragmentation model that fitted by one, the primary fragmentation model that fitted by Weibull distribution was added in the lower region to Weibull distribution was added in the lower region to predict the coal comminution from the predict the coal comminution from the devolatilization process. devolatilization process.

Figure 24Figure 24 Particle size distribution of initial particle: (a) input to Particle size distribution of initial particle: (a) input to shrinking shrinking core model simulation, (b) input to shrinking core core model simulation, (b) input to shrinking core model withmodel with primary fragmentation model. primary fragmentation model.

(a)

(b)

(a)

(b)

Figure 25Figure 25 Particle size distribution after devolatilization process at Particle size distribution after devolatilization process at 850 850 ooC,C, 1 atm: (a) no adding primary fragmentation model, (b) 1 atm: (a) no adding primary fragmentation model, (b) addingadding primary fragmentation model.primary fragmentation model.

Figure 26Figure 26 Particle size distribution after combustion in lower Particle size distribution after combustion in lower region at region at 850 850 ooC, 1 atm :(a) no adding primary fragmentation (b) C, 1 atm :(a) no adding primary fragmentation (b) adding adding primary fragmentation model.primary fragmentation model.

(a)

(b)

0.45

0.25

ConclusionsConclusionsConclusionsConclusions

The experiments on the fuels comminution

Primary fragmentation study

The models to predict the particle size distribution were The models to predict the particle size distribution were divided into two models divided into two models as showed in the following equations.as showed in the following equations.

For the small particles with size between 500-750 m

5.7

627exp1

l

M

lM

T

For the large particles with size between 1-3 mm

5.7

31013.2exp1

l

M

lM

T

Secondary fragmentation study

The models to predict the particle size distribution for the The models to predict the particle size distribution for the coal particles after combustion were divided into two coal particles after combustion were divided into two models as showed in the following equations: models as showed in the following equations:

For the fine particles

6.1

25exp1

l

M

lM

T

For the coarse particles

6

295exp1

l

M

lM

T

Industrial scale CFBC simulation

This section was proposed a model for simulating a CFBC using This section was proposed a model for simulating a CFBC using single or mixed fuels. The shrinking core model was included in single or mixed fuels. The shrinking core model was included in the simulation to calculate the size distribution and weight the simulation to calculate the size distribution and weight fractions in each region of the riser. The modification will reflect fractions in each region of the riser. The modification will reflect the phenomena in the riser better. Moreover, the detail of the phenomena in the riser better. Moreover, the detail of emission models were added in the simulation to predict the emission models were added in the simulation to predict the formation of NO, Nformation of NO, N22O, and SOO, and SO22. For different biomass fractions in . For different biomass fractions in

the fuel, the simulation output will demonstrate the trend of gas the fuel, the simulation output will demonstrate the trend of gas emission, which can be used for environment protection emission, which can be used for environment protection consideration. consideration.

Laboratory-scale CFBC simulation

The simulation in this section emphasized on the particle size The simulation in this section emphasized on the particle size distribution in the riser of the CFBC. Two case studies were distribution in the riser of the CFBC. Two case studies were simulated. The first case, only shrinking core model was added simulated. The first case, only shrinking core model was added to predict the PSD along the riser. The second case, the Weibull to predict the PSD along the riser. The second case, the Weibull distribution was added at the bottom of riser to predict the PSD distribution was added at the bottom of riser to predict the PSD after the devolatilization process. It was found that the sizes of after the devolatilization process. It was found that the sizes of particles were reduced along the riser. The second case could particles were reduced along the riser. The second case could be predicted the fine particles better than the first case. This be predicted the fine particles better than the first case. This was due to only the shrinking core model could not eliminate was due to only the shrinking core model could not eliminate the large particle in the system. The original size of particles still the large particle in the system. The original size of particles still remains at the top of riser. However, the result of the second remains at the top of riser. However, the result of the second case simulation was not coincided with the experiment result case simulation was not coincided with the experiment result because of the difference in operating modes. because of the difference in operating modes.

This research was studied the comminution of This research was studied the comminution of Thailand coal. The CCD camera and particle size Thailand coal. The CCD camera and particle size laser analyzer were used to measure the size of laser analyzer were used to measure the size of particles because these method disturb the particles because these method disturb the fragmented particles less than the sieve analysis fragmented particles less than the sieve analysis method. The Weibull distribution was used to method. The Weibull distribution was used to predict the particle size distribution for the predict the particle size distribution for the fragmented particles. Moreover, in the simulation fragmented particles. Moreover, in the simulation part, the PSD was predicted along the riser of the part, the PSD was predicted along the riser of the CFBC.CFBC.

Overall ConclusionsOverall ConclusionsOverall ConclusionsOverall Conclusions

Thank you for your attentionThank you for your attentionThank you for your attentionThank you for your attention