312 r.j.basavaraj

Chemical-Looping Combustion Steam Cycle for Power

Generation using Coal Synthesized Gas

ICAER 2013

by

R J Basavaraj , Sreenivas Jayanti

Department of Chemical Engineering

Indian Institute of Technology Madras

Chennai -600 036, India

Paper ID 312

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Outline of the presentation

2

• Chemical-looping combustion (CLC) technology

• Selection of oxygen carriers / support material, reactor configuration

• Analysis of syngas CLC system and lay-out studies

• Chemical-looping reactors, and heat exchangers, design

• Current focus

• Conclusions

Relevance of oxy-fuel combustion

3

Rise in global warming -Increase in CO2

level, ~388 ppm in 2010, the highest for 650000

years; Surface temperature rise of 0.74+0.18 C

over the 20th century

Possibility of reduction of CO2

from concentric sources – coal-fired

power plants, steel plants, cement kilns, steel

industries, refineries ..

Post combustion CO2 removal– Chemical looping combustion appearsto offer advantages over oxy-fuelcombustion and solvent capture

4

The countries that will be under water when

the ice caps melt

Possible submergence of coastal areas of

India due to melting of icecaps

5Image downloaded from the net around the time of announcement of a new nuclear power plant and energy

price rises in the UK recently. http://i.imgur.com/lHfiCD5.jpg

INDIA

http://i.imgur.com/lHfiCD5.jpg











Relevance of oxy-fuel combustion

6

Rise in global warming -Increase in CO2

level, ~388 ppm in 2010, the highest for 650000

years; Surface temperature rise of 0.74+0.18 C

over the 20th century

Possibility of reduction of CO2

from concentric sources – coal-fired

power plants, steel plants, cement kilns, steel

industries, refineries ..

Post combustion CO2 removal– Chemical looping combustion appearsto offer advantages over oxy-fuelcombustion and solvent capture

Chemical-looping combustion

7

Me

MeO

Fuel

Reactor

Air

Reactor

CO2, H2ON2 + unreacted O2

Abbreviations “Me” and “MeO” will be used as general terms for reduced and

oxygenated carrier respectively.

nMe + mAir → nMeO + Depleted air 4MeO + CH4 (fuel) → 4Me + CO2 + 2H2O

Figure 1. Schematic of chemical looping combustion system

Air

Me O

Me O

Fuel

Cm Hn

C ox RedConventional heat of combustion, ΔH = ΔH + ΔH

Chemical-looping combustion:

Technical issues

• Oxygen carriers and support materials

• Reactor configuration

• Heat balance and optimization

• Thermodynamic analysis

8

Selection of O2 carriers for gaseous Fuels

Inert Support**:

• Al2O3, SiO2, TiO2 , ZrO2,

NiAl2O4 and MgAl2O4

• NiAl2O4 is selected as a support

9

Figure 3. Conversion of CH4 to CO2 as a function of temperature*

Active metal oxide*:

• NiO, CuO, Fe2O3, CoO and

Mn3O4

• Reactivity of the oxygen carriers

NiO > CuO > Mn2O3 > Fe2O3

• NiO is chosen

*Hossain, M. M., & de Lasa, H. I, 2008, Chemical Engineering Science, 63(18), 4433–4451.

**Ryu, H., et al., 2003, Korean J. Chem. Eng., 20(1), 157–162.

Fe3O4/Fe0.947 O

CoO/Co

NiO/Ni

Fe0.947O/Fe

Cu2O/Cu Mn3O4/MnO Fe2O3/Fe3O4

0

0.2

0.4

0.6

0.8

1

800 1000 1200 1400 1600

Co

nv

ersi

on

of

CH

4to

CO

2

T (K)

Reactor configurations being reported in the

literaturePlace Configuration Fuel ReferenceGaseous fuels

Chalmer University of Technology, Sweden Interconnected CFB-BFB NGLinderholm et al. Int. J. of Green

house Gas Control 2008;2:520-30.

Institute of Carboquimica, Spain Interconnected BFB-BFB CH4

Garcia et al. Fuel 2007;86:1036-45.

Xi' an Jiaotong University, China Interconnected CFB-BFBCoke

oven gas

Wang et al. Energ. Environ. Sci.

2010;3:1353-60

ALSTOM Power Boilers, France Interconnected CFB-BFB NGMattisson et al. Energy Procedia

2009;1:1557-64.

Korean Institute of Energy Research, Korea Interconnected CFB-BFBCH4,

CO, H2

Adanez et al. Ind Eng Chem Res

2006;45:6075-80.

Technical university Vienna, Austria DCFBCH4,

CO, H2

Kolbitsch group. Int J Greenhouse

Gas Control 2010;4:180-5.

Solid fuels

Chalmer University of Technology, Sweden Interconnected CFB-BFBCoal,

petcoke

Berguerand N, Lyngfelt A. Fuel

2008;87:2713-26.

Southeast university, China CFB-spouted bedcoal,

biomass

Shen et al. Energ Fuel 2009;23:

2498-505.

Ohio State University, USAInterconnected moving bed-

entrained bedCoal

Ohio State University. NETL project

NT005289

ALSTOM Windsor, Connecticut, USA Interconnected CFB-CFB Coal

Andrus H.E., Proc. 34th Int. Tech.

Conf. on Clean Coal & Fuel

Systems. Clearwater, Florida, USA;

2009.

10CFB-Circulating Fluidized Bed

BFB-Bubbling Fluidized Bed

DCFB-Dual Circulating Fluidized Bed

Progression of plant efficiency via advanced

steam conditions and plant Designs

11

T91

Clean Coal Combustion: Meeting the Challenge of Environmental and Carbon Constraints by ALSTOM (USA), 2010

1960 1980 2000 20202010

Material Development

-Efficiency (net) HHV

-Typical Steam Parameters

35-37%

37-38

41%- 43%

TARGET

48 - 50 %

Ni-based

Materials

Mature

Supercritical

3480/1005/1050 (psi/ F/ F)

2400/1005/1005

167/540/540

Up to

5400/1300/1325(psi/ F/ F)

4000/1110/1150(psi/ F/ F)

4000/1075/1110

(psi/ F/ F)

38-41%

Subcritical

Technology

Commercial

State of Art

Supercritical

UltraSupercritical

Advanced USC

Sliding

Pressure

Supercritical

Advanced

Austenitic

Materials

12Korian Institute of Energy Research, 2010

Future research direction

Reactor configurations being reported in the

recent literature

Figure 4. Process diagram of the double loop circulating fluidized bed reactor system

13Bischi et al. 2011, International Journal of Greenhouse Gas Control, 5(3), 467-474.

Syngas fueled CLC plant lay-out studies

14

Assumptions

1. Adiabatic reactors.

2. Complete oxidation and reduction reactions.

3. No reforming reaction's in fuel reactor and fuel is completely

converted to CO2 and H2O.

Composition* of coal synthesized gas

Species Formula Mole %

Hydrogen H2 45.7

Carbon

monoxideCO 19.6

Methane CH4 6.6

Carbon dioxide CO2 28.1

LHV 11.2 MJ/kg

*Winslow, A.M., 1977, International symposium on combustion, 16, 503–513.

Reactions and operating variables

Reaction of Ni/NiO on nickel-spinel (NiAl2O4) support*

15

Variables

Operating Temperature : Air reactor (1000 C) and Fuel reactor (900 C)

Reactor system operating pressure: 1atm

Particle Composition by weight: 60% NiO + 40% NiAl2O4

Average Particle size: 200 micron; Sphericity: 0.99

o

o

2 1000

2 927

2 2

Air reactor:

2 ( ) 2 H 468 kJ/mol

Fuel reactor:

( ) ( ) H 48 kJ/mol

( ) ( )

C

C

Ni O g NiO

NiO CO g Ni CO g

NiO H g Ni H O g o

o

927

4 2 2 927

H 15 kJ/mol

4 ( ) 4 2 ( ) H 133 kJ/mol

C

CNiO CH g Ni H O CO g

*Adanez, J., et al., 2012, Progress in Energy and Combustion Science, 38(2), 215–282.

Reactors heat balance and supercritical

steam cycle

16

Pump

QExhaust

Power

Air reactor

Fuel reactor

QAir

QMeO

QDepleted air

QMe

QFuel

Water removal and

CO2 sequestration

Cooled depleted air

to atmosphere

Gas

Solids

Steam/water

TurbineQAR, Extract

QOx

QRed

Air in Me Ox Depleted air MeO AR, ExtractAir reactor: Q + Q + Q = Q + Q + Q

Fuel in MeO Red Exhaust MeFuel reactor: Q + Q - Q = Q + Q

Figure 5a. CLC reactor system heat balance

2

55 bar

14 bar

0.069 bar

600 C 600 C 600 C

T

S

CP

1 3 5

4

7

86

.. .

. ..Figure 5b. T-s diagram of supercritical, double

reheat 240 bar/600/600/600 C steam cycle*

Heat balance of 800 MWth Syngas fueled CLC plant

Preheated Fuel

T = 200°CQ = 20.25 MW

MeO (NiO : NiAl2O4)

QMeO= 402.85 MW

Temperature (°C) = 1000

MeO flow rate (kg/s) = 411.36

Depleted Air [N2 =183.19 kg; O2 = 2.78 kg]

Q= 201.82 MW


Depleted air flow rate (kg/s) = 185.97

Q = 70.92 MW



Air


Air flow rate (kg/s) = 238.85

Air reactor

Preheated Air

T = 550°CQ = 130.90 MW

Q = 133.67 MW


Exhaust gas flow rate (kg/s) = 124.3

Fuel Reactor

Synthesis gas from coal


Fuel flow rate (kg/s) = 71.43

Me (Ni : NiAl2O4)

QMe= 237.62 MW


Me flow rate (kg/s) = 358.49

Exhaust [CO2 = 86.1 kg; H2O = 38.2 kg]

Q= 154.01 MW



T = 1000°C

QOx = 773.2 MW

ΔH = -ve

T= 900°C

QRed = 26.8 MW

ΔH = -ve

Fuel-preheaterAir-preheater

Q AR, Extract = 537.08 MW

Q FR, Extract = 58.30 MW

QTotal, Extract = 595.38 MW

17

Preheated Fuel

T = 200°CQ = 20.25 MW

MeO (NiO : NiAl2O4)

QMeO= 349.09 MW


MeO flow rate (kg/s) = 411.36

Depleted Air [N2 =183.19 kg; O2 = 2.78 kg]

Q= 179.41 MW



Q = 58.3 MW



Air


Air flow rate (kg/s) = 238.85

Air reactor

Preheated Air

T = 513°CQ = 121.17 MW

Q = 135.33 MW



Fuel Reactor

Synthesis gas from coal


Fuel flow rate (kg/s) = 71.43

Me (Ni : NiAl2O4)

QMe= 240.54 MW


Me flow rate (kg/s) = 358.49

Exhaust [CO2 = 86.1 kg; H2O = 38.2 kg]

Q= 155.63 MW



QAR, Extract = 606.45 MW

T = 900°C

QOx = 773.2 MW

ΔH = -ve

T= 908°C

QRed = 26.8 MW

ΔH = -ve

Fuel-preheater Air-preheater

Optimised Heat Balance of syngas fueled 800 MWth CLC plant

18

Stream P, bar T, °C m, kg/s h, kJ/kg

A1 1.0132 30 238.85 0

A2 1.0132 513 238.85 507.33

A3 1.0132 900 185.97 964.68

A4 1.0132 327 185.97 313.46

A5 1.0132 70 185.97 41.54

F1 1.0132 30 71.43 0

F2 1.0132 200 71.43 283.51

E1 1.0132 908 124.30 1252.03

E2 1.0132 807 124.30 1088.78

E3 1.0132 80 124.30 59.09

E4 1.0132 40 124.30 11.67

E5 1.05 40 38.20 18.73

E6 1.05 40 86.09 8.54

E7 110 35 86.09 4.26

S1 243.12 39 116.73 184.82

S2 243.12 252 116.73 1096.48

S3 243.12 39 46.12 184.82

S4 243.12 252 46.12 1096.48

S5 240 252 162.85 1096.48

S6 240 600 162.85 3502.91

S7 55 305 162.85 2922.83

S8 55 600 162.85 3662.80

S9 14 332 162.85 3117.56

S10 14 600 162.85 3695.40

S11 0.069 39 162.85 2573.72

S12 0.069 39 46.12 2573.72

S13 0.069 39 116.73 2573.72

M1 1.01325 900 411.36 848.61

M2 1.01325 908 358.49 670.97

Thermodynamic analysis of CLC power

plant and supercritical steam cycle

19

E4

Four stage compressor with

intercooling

E6

Air

preheater

Fuel

preheater

M1

M2

S8

S6

A3

E1

Air reacto

r

Fuel reacto

r

S10

S7

HP

S9

MP

LP

S11

F2

A4

S3

E2

E5

S13

S12S4

S2

F1

A5

A2

A1

S1

E3Flue gas conditioner

E7

HE1

HE3

HE2

S5

Pump 1 Pump 2

Condensate

preheater 1

Condensate

preheater 2

Stream

A- Air

E- Exhaust

F- Fuel

M- Metal/Metal oxide

S- Water/steam

HP- High pressure

MP- Medium pressure

LP- Low pressure

255 bar

14 bar

0.069 bar

600 C 600 C 600 C

T

S

CP

1 3 5

4

7

86

. . .

. ..T-s diagram of supercritical,double

reheat 240 bar/600/600/600 C

steam cycle*

CP-Critical point

*El-Wakil.; Mohamed, M. Power Plant Technology, New York, 2010, PP. 40-71.

CLC power plant lay-out configuration

20Figure 7. General arrangement for gaseous chemical-looping combustion.

CFB- Circulating Fluidized Bed

BFB- Bubbling Fluidized Bed

21

Possible carbon capture and sequestration options*

*Intergovernmental Panel on Climate Change (IPCC)-2005

Overall energy analysis

22

CLC steam cycle power plant: 240 bar/600/600/600 C

Fuel Syngas Revised Syngas

AR Temperature, C 1000 900

FR Temperature, C 900 908

AR cooling heat capacity, MWth 537 606

FR cooling heat capacity, MWth 58 0

HP turbine, MWe 94 94

MP turbine, MWe 88 88

LP turbine, MWe 182 182

Total production, MWe 365 365

CO2 compression, MWe 31 31

Water pumping, MWe 5 5

Total power consumption, MWe 36 36

Total useful output, MWe 329 329

Thermal input, MWth 800 800

Gross efficiency 45.74 45.74

Net efficiency 41.22 41.22

AR: Air reactor, FR: Fuel reactor, HP: High pressure , MP: Medium pressure and LP: Low pressure

Chemical-looping combustion system:

layout design Issues

• Chemical-looping reactor design

PFR Factors

Particle Residence Time

Fluidization Regimes in Reactor System

Reaction Kinetics

• Heat transfer area

23

Chemical-looping reactor Design (Cont…)

24*Naqvi R. 2006, Analysis of Natural Gas-Fired Power Cycles with CLC for CO2 Capture. Doctoral Theses: NUST.#Kunii D, Levenspiel O. 1991, Fluidization Engineering. 2nd Ed. Washington: Butterworth-Heinemann.

1 Fuel flow (kg/s)

2 Air flow (kg/s)

3 Area of reactor (Air /Fuel)

4 Solids holdup in the CFB air reactor (kg)

5 Solids holdup in BFB fuel reactor (kg)

6 Average solid fraction in CFB air reactor

7 Average solid residence time t = solids holdup/solids flow rate

ParameterBFB Fuel

Reactor

CFB Air

Reactor

Gas flow (kg/s) 71.43 238.85

Gas density at reactor temperature (kg/m3) 0.3848 0.3011

Gas velocity (m/s) 2.10 4.7

Oxidation area (m2) 87.14 170.31

Diameter of column (m) 10.54 14.73

Length of column (m) 1.50 45

Density of metal (kg/m3) 2420 2420

Average solid fraction 0.40 0.0011

Hold up mass (kg) 126533 20669

Mass flow of metal/metal oxide at reactor exit (kg/s) 358 411.36

Average solids residence time (s) 353 50

25

(Cont…) Chemical-looping reactor design

Fluidization regimes†

26

Bubbling fuel reactor

10-2

10-1

10-3

1

10

1 10 102

Circulating fluidized

bed air reactor

Syngas Lay-out AR

Syngas Lay-out FR

Air reactor Fuel reactor

dp, m dp* u, m/s u* dp, m dp* u, m/s u*

0.0002 2.91 4.7 2.01 0.0002 4.23 2.1 1.06

† Kunii D, Levenspiel O. 1991, Fluidization Engineering. 2nd Ed. Washington: Butterworth-Heinemann.

Heat transfer area

27

Heat exchanger Q, kW U, kW/m2K ∆TLMTD, K A , m2

Air-preheater 121173 0.110 340 3240

Fuel-preheater 20250 0.112 742 248

Embedded Heat exchanger 1 391885 0.216 452 4015



1

Fluidized bed to surface heat transfer coefficient

(neglecting radiation effect) is given by the

Zabrodsky’sEquation* (W/m2K)

2Botterill Recommendationfor effective heat

transfer* (W/m2K)

3Heat transfer co-efficient on fluid side

( W/m2K)

4 Overall heat transfer co-efficient (W/m2K)

5 Heat exchanger surface area (m2)

*Simeon NO. Fluidized Bed Combustion. Basel: Eastern Hemisphere; 2004.

Current focus

• Studies are in progress to develop a Dual-fuel CLC power plant

layout for natural gas as well as syngas without affecting steam side

load.

• Catalyst NiO:NiAl2O4 (60:40 by mass) is prepared. Experimental

studies on fuel reactivity.

28

Stack

Air

CO

CH

4

Gas Analyser: O2, N2

Gas Analyser: H2, CH4, CO, CO2

Fluidized

bed reactorElectric coil heating

arrangement

Moisture Trap

Conclusions

• From the energy balance and thermodynamic analysis of syngas fuelled 800

MWth CLC system, a power plant layout is made.

• Thermodynamic calculations show that CLC-steam cycle is capable of

achieving overall net cycle efficiency up to 41.22%. This efficiency includes

100% carbon capture.

• The aerodynamics, particles residence time of the CLC reactor system has

been studied. Enough heat transfer area is provided in heat exchanger so that

required amount of heat transfer to takes place.

• The proposed lay-out is designed in such a way that CLC plant operates at

atmospheric pressure on the fuel side and generates supercritical steam (240

bar/600/600/600oC) on the steam side to run a steam turbine while

maintaining a high overall thermal efficiency and a net electrical output of

330 MWe.

29

THANK YOU

30

31

Geological Storage of CO2

• IPCC (2005)

Potential storage sites spread all over the world

312 r.j.basavaraj

Technology

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