Shahin Zarghami, Hamid Arastoopour, Javad Abbasian, Emadoddin Abbasi, Emad Ghadirian

Illinois Institute of Technology, Chicago, IL

The overall objective of the program is to develop aComputational Fluid Dynamic (CFD) model and toperform CFD simulations to describe theheterogeneous gas-solid absorption andregeneration and WGS reactions in the context ofmultiphase CFD for a regenerative magnesiumoxide-based (MgO-based) process for simultaneousremoval of CO2 and enhancement of H2 productionin coal gasification processes.

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The Project consists of the following four (4) tasks:

Task1. Development of a CFD/PBE model accounting for the particle (sorbent) porosity distribution and of a numerical technique to solve the CFD/PBE model. (Completed)

Task2. Determination of the key parameters of the absorption and regeneration and WGS reactions. (Close to Completion)

Task3. CFD simulations of the regenerative carbon dioxide removal process. (Close to Completion)

Task4. Development of preliminary base case design for scale up. (In Progress)

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Process Economics is highly dependent on the CO2 Sorbent properties

CO2 absorption Temperature (300 - 450 ˚C)

Simple regeneration

Sulfur and Steam Resistant

Sorbent Cost (per cycle)

0.01

0.1

1

10

300 350 400 450 500PC

O2

, atm

Temperature, ˚C

DESORPTIONMgCO3 MgO+CO2

Advanced Power Plant

ABSORPTIONMgO+CO2 MgCO3

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Dolomite

Calcination

Impregnation

Re-Calcination

CaCO3, MgO

Half- Calcined Sorbent

CaCO3, MgO , Mg(OH)2, K2CO3

Impregnated Sorbent

CaCO3, MgO , K2CO3

Re-Calcined Sorbent

Fresh Dolomite

Modified Dolomite

MgCa(CO3)2

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T

T

P P

P P

MFC

MFC

P

CO2

N2

Data Acquisition &Control System

PressureRegulator

Bubble Flow meter

Vent

Frit

Bed of Sorbent

Quartz Beads

9 cm

8 cm45 cm

30 cm

Thermocouple

Reactor Body

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0

0.2

0.4

0.6

0.8

1

0 0.1 0.2 0.3 0.4 0.5

MgO

Con

vers

ion,

K/Mg Molar ratio

0

0.02

0.04

0.06

0.08

0.1

0 0.1 0.2 0.3 0.4 0.5

Tota

l Por

e Vo

lum

e , m

l/gr

K/Mg Molar ratio

Hasanzadeh et al. 

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0

0.2

0.4

0.6

0.8

1

0 10 20 30 40 50

MgO

Con

vers

ion

Time, min

310˚C

340˚C

480˚C

390˚C

430˚CP=20 atmCO2:50 mol%N2:50 mol%

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0

0.2

0.4

0.6

0.8

1

0 5 10 15 20 25 30

MgO

Con

vers

ion

Time,min

5% Steam10% Steam30% Steam

No Steam

T=430 ˚CP=20 atmCO2:50 mol%N2: Balanced

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0

0.2

0.4

0.6

0.8

1

300 340 380 420 460

MgO

Con

vers

ion

Temperature, ˚C

P=20 atmCO2:50 mol%N2: Balanced30% Steam

10% Steam

Reaction time : 5min

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0.0

0.2

0.4

0.6

0.8

1.0

0 5 10 15 20 25 30

Dec

ompo

sitio

n

Time, min

500 ˚C

450 ˚C

550 ˚C

525 ˚C

MgCO3 MgO + CO2

P=20 atmN2=100%

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0.0

0.2

0.4

0.6

0.8

1.0

0 5 10 15 20 25 30

Dec

ompo

sitio

n

Time, min

Dry Carbonation-Dry Regeneration

Dry Carbonation-Wet Regeneration

P= 20 barT= 500˚C

Clean Coal Gas

Concentrated H2 Stream

Car

bona

tor

Reg

ener

ator

N2

With & Without Steam

N2 & Steam

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0.0

0.2

0.4

0.6

0.8

1.0

0 5 10 15 20

Dec

ompo

sitio

n

Time, min

T=500˚CP= 20 bar

No CO2

10 mol% CO2

20 mol% CO2

0.0

0.2

0.4

0.6

0.8

1.0

0 5 10 15

Dec

ompo

sitio

n

Time, min

T=550˚CP= 20 bar

No CO2

10 mol% CO2

20 mol% CO2

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0

0.2

0.4

0.6

0.8

1

1.2

0 4 8 12 16 20 24

Con

vers

ion

Number of Cycles

Wet Carbonation-Wet Regeneration

Wet Carbonation-Dry Regeneration

Dry Carbonation-Dry Regeneration

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0 4 8 12 16 20 24K

/Mg

Mol

ar ra

tio

Number of Cycles

Wet Carbonation-Wet Regeneration

Wet Carbonation-Dry Regeneration

Dry Carbonation-Dry Regeneration

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0

0.2

0.4

0.6

0.8

1

0 0.03 0.06 0.09 0.12 0.15 0.18 0.21 0.24 0.27 0.3

MgO

Con

vers

ion

K/Mg Molar ratio

Fresh SorbentHasanzadeh et al.Carb. Wet (430 C)-Dec. Dry (550 C)Carb. Wet (430 C)- Dec. Wet( 550 C)Carb. Dry (430 C)- Dec. Dry ( 550 C)

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Abbasi et al., Fuel, 2013

3 )1( ZXXrr pp productreact

reactproduct

MM

Z

)

111()1(1

)1)((3

331

32

XZXXXr

Dk

XCCNk

rdtdX

pg

s

eboMgO

s

p

0 ( )g gD D X

Product Layer

Reactive Zone

Un‐reactive Zone

r’p

rp

rc ri

K

Ca Mg

22

1 0 eCD r

r r r

'. .1: @ b pBC C C r r

e. .2 : (C -C ) @ e s i iCBC D k r rr

2

1 ( )4

MgOMgO s i e

i

dNr k C C

r dt

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0.00

0.10

0.20

0.30

0.40

0.50

0.60

0 5 10 15 20 25 30 35

MgO

Con

vers

ion

Time, Min

T= 450 CT= 410 CT= 380 CT= 360 C

CO2/N2/H2O = 50/40/10

Carbonation

0.00

0.20

0.40

0.60

0.80

1.00

0 5 10 15 20 25 30

MgC

O3

Dec

ompo

sitio

n

Time, min

T=550 CT=525 CT=500 CT=450 C

Regeneration

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Preliminary Base case design and Simulation Results

Based on DOE/ NETL Carbon Capture Unit. (Courtesy of Larry Shadle, NETL)

3.35 m

LocationNominal gas Flow 

(g/s)

Adsorber 5

Loop seal 1 0.7

Loop seal 2 0.8

Regenerator 1

Move air 0.14

Mean Particle size = 185 μmParticle density = 2480 kg/m3

15 cm

15 cm

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Chugging every 0.4-0.6 sec

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NETL experimental imagesevery 0.4-0.6 sec “Chugging occurs when a large mass of particles

lifts from the fluidized bed and moves into the cone leading into the riser. The cone-constriction prevents particles from flowing smoothly into the riser and particles plug the riser pipe.”

Clark et al., Powder Tech. 2013

a                       b                       c

22/29Experimental data reported by Clark et al., Powder Tech. 2013

Syamlal-O’Brien EMMS

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0

0.2

0.4

0.6

0.8

1

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0 50 100 150 200 250 300 350

MgCO3 conv

ersion

CO2 mole fraction

Time (s)

CO2 mole fraction

MgCO3 conversion

inlet CO2mole fraction T=550◦CP=20 atm

CO2 concentration [=] kmol/m3

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Schaeffer Model

-bypassing of the fluidizing gas through the lower seal pot

- Bubbling standpipe

s fr s kin col s fr s kin col fr

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Schaeffer Model

(With Modified Johnson-Jackson frictional Pressure)

Modified  μfr

Schaeffer frictional model (which is based on coulomb law)has two major shortcomings:

1) It is discontinuous (solid volume fraction ~ 0.5)

2) It is under predicting the frictional viscosity

Schaeffer frictional model Continuous frictional model

Sundaresan frictional model Laux frictional model

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model Prediction, Angle of ReposeSchaeffer 0

Sundaresan 21

Laux 29.5

Experiment 36

Investigation of proper modeling of very dense granular flows in the recirculation system of CFBs, Nikolopoulos et al, Particuology, 2012.

Schaeffer frictional model Sundaresan frictional model Laux frictional model

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Effect of WGS reaction

Modeling of combined absorption & WGS reactions

Further modification of solid frictional viscosity.

Completion of full loop simulation by including reaction and

population balance model for density changes.

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Thanks for your attention

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0

0.2

0.4

0.6

0.8

1

300 340 380 420 460

MgO

Con

vers

ion

Temperature, ˚C

P=20 atmCO2:50 mol%N2: Balanced

30% Steam

10% Steam

Reaction time : 5min

MgO + H2O MgO.H2O*

MgO.H2O* + CO2 MgCO3 + H2OWith Steam

MgO + CO2 MgCO3Without Steam30/29

Eulerian- Eulerian Approach in combination with the kinetic theory of granular flow

Assumptions: Uniform and constant particle size and density‐Conservation of Mass

‐ gas phase:

‐ solid phase

‐Conservation of Momentum‐ gas phase:

‐ solid phase

‐Conservation of solid phase fluctuating Energy

‐ solid phase

gggggg mvt

).()(

ssssss mvt

).()(

)(.).()( sggsggggggggggg vvgPvvvt

)(.).()( sggsssssssssssss vvgPPvvvt

Numerical Modeling: Conservation Equations

Generation of energy due to solid

stress tensor

Diffusion dissipation

ssssssssss vIpvt

).(:)(]).()([

23

Abbasi and Arastoopour , CFB10, 2011 31/29

Gas-solid inter-phase exchange coefficient: EMMS model

Heterogeneity Factor

ω < 1 sg

)()1(

43

0 gDsggp

gg Cuud

p

sggg

pg

gg

d

uu

d

)1(75.1

)1(150 2

2

74.0g

74.0g

)( g

0044.0)7463.0(40214.05760.0 2

g

0040.0)7789.0(40038.00101.0 2

g

g8295.328295.31

82.074.0 g

97.082.0 g

97.0g

Numerical Modeling: Drag Correlation

(Wang et al. 2004)

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