CALCIUM LOOPING PROCESS FOR CLEAN FOSSIL FUEL … septiembre/C27.pdf · Shwetha Ramkumar, Robert M. Statnick, Liang-Shih Fan William G. Lowrie Department of Chemical and Biomolecular

CALCIUM LOOPING PROCESS FOR CLEAN FOSSIL FUEL CONVERSION

Shwetha Ramkumar, Robert M. Statnick, Liang-Shih Fan

William G. Lowrie Department of Chemical and Biomolecular Engineering The Ohio State University

Columbus, Ohio, USA

Daniel P. Connell

CONSOL Energy Inc.Research & Development

South Park, PA, USA

Patent Application -

WO2008039783

1st

Meeting of the High Temperature Solid Looping Cycles NetworkSeptember 15th

–September 17th

U.S. Patent Application No. 61/116,172

Equilibrium Limited Water Gas Shift Reaction (WGSR)

Temperature (0C)

100 200 300 400 500 600 700 800 900 1000 1100

KW

GS

1

10

100

1000

10000CO + H2

O CO2 + H2

Cu

Fe

MoS2

High Steam/CO

H2/CO ratio can be improved

But can never maximize H2

production

Further CO cleanup will be required for PEM fuel Cells (ppm levels)

Steam Gasification:

Coal + H2

O CO + H2

Hydrogen Synthesis from Coal

+ H2

S CaS + H2O+ COS CaS + CO2+ HCl CaCl2 + H2O

Specific Objectives

Simultaneous WGSR, CO2 removal, sulfur and halide capture integrated in one module

High purity H2 production

Reduce excess steam requirement

Remove H2S, COS and HCl to ppm levels

CO + H2

O CO2 + H2

+

CaO

CaCO3

Patent Application # WO2008039783 (2008)

Sulfur By-Product

Sulfur By-Product

Fly Ash By-Product

Fly Ash By-Product

Slag By-Product

Slag By-Product

Sulfur By-Product

Sulfur By-Product

Sulfur By-Product

Sulfur By-Product

Fly Ash By-Product

Fly Ash By-Product

Fly Ash By-Product

Fly Ash By-Product

Slag By-Product

Slag By-Product

Slag By-Product

Slag By-Product

Conventional Syngas Process

Steigel and Ramezan, 2006

Fuels &ChemicalsAir

Separation

Hydrogen

FuelCell

Steam

Slag SteamTurbine

Gas Turbine

AirCompressor

Stack

HRSG

RotaryCalciner

INTEGRATEDWGS +H2S

+COS + HCLCAPTURE

Generator

Gasifier

BFW

To SteamTurbine

CO2

Air

AirOxygen

CaO

CaCO3

SteamH2+O2

Calcium Looping Process


Hydrator



Net HeatOutput Heat

Input

Pure CO 2 gas

Calcination: CaCO3 CaO + CO2CO + H2O CO2 + H2

CaO + CO2 CaCO3

CaO + H2S CaS + H 2O

Syngas

Hydrogen

reactor

RegenerationReaction

2 gas

Calcination: CaCO3 CaO + CO2WGSR : O CO2 removal : CaO + CO2 CaCO3

Sulfur : CaO 2S CaS O

IntegratedHydrogen

CaCO3

CaO

Calciner

H2O

Reactivation

HydratorCa(OH)2

CaOHydration :CaO + H2O Ca(OH)2

OutputHeat

Ca(OH)2 CaO + H2ODehydration :

Halide : CaO + 2HX CaX2 + H2O

Net HeatOutput Heat

Input

Pure CO 2 gas

Calcination: CaCO3 CaO + CO2Calcination: CaCO3 CaO + CO2CO + H2O CO2 + H2

CaO + CO2 CaCO3

CaO + H2S CaS + H 2O

Syngas

Hydrogen

reactor

RegenerationReaction

2 gas

Calcination: CaCO3 CaO + CO2Calcination: CaCO3 CaO + CO2WGSR : O CO2 removal : CaO + CO2 CaCO3

Sulfur : CaO 2S CaS O

IntegratedHydrogen

CaCO3

CaO

Calciner

H2O

Reactivation

HydratorCa(OH)2

CaOHydration :CaO + H2O Ca(OH)2

OutputHeat

Ca(OH)2 CaO + H2ODehydration :

Halide : CaO + 2HX CaX2 + H2O

Patent Application # WO2008039783 (2008)U.S. Patent Application No. 61/116,172

Thermodynamic Analyses

Carbonation :Temperatures below 800C for a CO2

partial pressure of .4 atmTemperatures below 1000C for a CO2

partial pressures of 4.6 atm

Sulfidation :Outlet H2S concentration as steam partial

pressure and temperatureConventional System - 1000 ppm H2SCalcium looping - <1 ppm H2S

Temperature (oC)

400 500 600 700 800 900 1000

Equi

libriu

m H

2S C

onc

(ppm

)w

ith 3

0 at

m to

tal p

ress

ure

0.01

0.1

1

10

100

1000

1000020 atm 2 atm0.2 atm0.02 atm

CaO+ H2S CaS + H2OCaO+ H2S CaS + H2O

CLP

ConventionalIGCC

Hydration

Carbonation

Temperature (C)400 600 800 1000Eq

ulib

rium

Par

tial P

ress

ure

(atm

)

10-8

10-7

10-6

10-5

10-4

10-3

10-2

10-1

100

101

102

P H2O P CO2

CaO + CO2 CaCO3CaO + H2O Ca(OH)2

Hydration

Carbonation

Temperature (C)400 600 800 1000Eq

ulib

rium

Par

tial P

ress

ure

(atm

)

10-8

10-7

10-6

10-5

10-4

10-3

10-2

10-1

100

101

102

P H2O P CO2

CaO + CO2 CaCO3CaO + H2O Ca(OH)2


Experimental Setup Combined WGSR and CO2

Removal

•500-1500 sccm•3-15 % CO•Steam/CO =1:1-

3:1•600 –

700 oC•5000 ppm H2

S

N2

Steam Generator

QuartzWool

Packing

Water InSteam &

Gas Mixture

Sorbent&

CatalystPowderMixture

Heated Steel TubeReactor

Thermocouple

Water Trap

Analyzers (CO,CO2, H2, H2S)

Cold Fluid In

Cold Fluid Out

Water SyringePump

HeatExchanger

MixtureMixture

COH2 CO2

MFC MFC MFC MFC

N2

BackPressureRegulator

HydrocarbonAnalyzer

Temperature (oC)

500 600 700 800

CO

Con

vers

ion

(%)

0.0

0.2

0.4

0.6

0.8

1.0

0 psig 150 psig 300 psig

CO + H2

O Catalyst

CO2

+ H2

Time (sec)

0 500 1000 1500 2000

H2

Gas

Com

posi

tion

(%)

0

20

40

60

80

100

0 psig150 psig 300 psig

CO + H2

O CO2

+ H2

CaO

Catalyst/Sorbent WGS System

Catalyst CaO Sorbent

IncreasingPressure

14.7 Psi 14.7 Psi150 Psi300 Psi

150 Psi300 Psi


H2

Production with H2

S removal Non catalytic -

Effect of Steam to CO ratio

Time(sec)1000 2000 3000 4000

H2S

con

cent

ratio

n (p

pm)

0

200

400

600

800Steam to CO = 0.75:1Steam to CO = 1:1Steam to CO = 3:1

25 ppmH2

S 8 ppmH2

S0 ppm H2

S

Time(sec)

0 1000 2000 3000C

O C

onve

rsio

n0.0

0.2

0.4

0.6

0.8

1.03-1 1-1 0.75-1

CO + H2

O H2

+ CO2

CaO

H2

S

CaCO3 CaS

Pressure : 14.7 Psia


H2

Production with H2

S removal Non catalytic –

Effect of Temperature

H2S Outlet Concentration with Temperature

Lowest at 560-600C

Time(sec)500 1000 1500 2000 2500 3000

H2S

con

cent

ratio

n (p

pm)

0

200

400

600

800600C560C650 C700C

Time(sec)0 500 1000 1500 2000 2500 3000

Gas

Com

posi

tion

(%)

0

20

40

60

80

100560C600C650C700C

S/C ratio = 1:1P= 0 psig

Greater extent of carbonation 600-650C

Optimum temperature for sulfidation and carbonation– 600C


H2

Production with H2

S removal Non catalytic –

Effect of Pressure

Time (sec)0 1000 2000 3000 4000 5000

H2S

con

cent

ratio

n (p

pm)

0

200

400

600

800300 psig0 psig

300 psig

0 psig

< 1 ppm

Time(sec)0 1000 2000 3000 4000

H2

Gas

Com

posi

tion

(%)

0

20

40

60

80

100

0 psig300 psig

300 psig

0 psig

High purity H2

S/C ratio = 1:1T = 600C

Higher pressure favors sulfidationH2S in the outlet

0 psig – 20 ppm 300 psig <1 ppm

High pressure favors combined carbonation and WGSR

H2 in the outlet0 psig – 70%300 psig – 99.97%

Presence of calcium oxide removes equilibrium limitation of WGSR


Sorbent Reactivity and Recyclability

Effect of Realistic Calcination Conditions

0

10

20

30

40

50

60

70

OriginalSorbent

0% 33% 50%

Steam Concentration in Carrier Gas

W

t% C

aptu

re

0

10

20

30

40

50

60

70

OriginalSorbent

1 2 3

Number of Cycles

W

t% C

aptu

re

Sorbent reactivity reduced to half during calcinationEffect of sintering reduced by steam calcinationIncrease in steam concentration improves reactivity

Calcination at 900C with 50% steam and 50% CO2

Reduced sintering over multiple cyclesReactivity reduced to half in 4 cycles


Reactivation of the Sorbent

Sorbent reactivity reduced to a third after calcination at 1000C

Calcined sorbent regenerated completely by hydration

0

10

20

30

40

50

60

OriginalSorbent

CalcinedSorbent

WaterHydration

SteamHydration

W

t % C

aptu

re

0

10

20

30

40

50

CalcinedSorbent

100 psig 150 psig 300 psig

Hydration Pressure

Wt %

Cap

ture


Techno-Economic Evaluation CLP for High-Purity Hydrogen Production

Compare the technical and economic performance of the Calcium Looping Process (CLP) with the performance of the conventional coal-to-hydrogen process for a commercial-scale plant

Both processes modeled using a common basis– Illinois No. 6 coal (27,135 kJ/kg HHV, 2.5% sulfur as received)– GE Energy gasifier with 226 tonne/h coal feed– Hydrogen produced at 99.9% purity, ≥

20.7 bar– CO2

compressed to 151 bar

Results obtained from Aspen Plus® and spreadsheet-based models

This is a work-in-progress; results are preliminary

Techno-Economic Evaluation CLP for High-Purity Hydrogen Production

Coal-to-Hydrogen Process

Air Separation

Unit

Gasifier

Quench

Shift Reactors

Syngas Scrubber

2-Stage Selexol

Coal Prep and Feed

Slag Handling

CO2

Compression Dehydration

Pressure Swing

Adsorber

Boiler

Radiant Cooler

Syngas Cooling

Mercury Removal

Claus

Plant

Steam Turbine

Coal Water

AirSlag

Sulfur

Flue Gas

Pure H2

CO2

Air

Coal-to-Hydrogen Process

Air Separation

Unit

Gasifier

Coal Prep and Feed

Slag Handling

CO2

Compression Dehydration

Pressure Swing

Adsorber

Radiant Cooler

Steam Turbine

Coal Water

AirSlag

Pure H2

CO2

CalciumLooping Process

Coal

Limestone

Solid Waste

CLP Aspen Plus®

Process Model Process Flow Diagram

Syngas from

Radiant Cooler

Hydrogen Product

Coal

Oxygen from ASU

Solid Waste

Limestone

CO2

to Compressor

Hydrator

CarbonatorCalciner

FSPLIT

MIXER

MIXERRGIBBS

FSPLIT MIXER

FSPLIT

RYIELD

RGIBBS

FSPLIT

CLP Aspen Plus®

Process Model Key Assumptions

Carbonator– T = 677 °C

–

P = 22 bar– Ca/C molar ratio = 1.3– All required steam provided by hydrated lime and syngas

Calciner– T = 840 °C

–

P = 1 bar– Fuel: coal (Illinois No. 6) and PSA tailgas with oxyfiring

Solids purge = 6 %

Heat is recovered from the following sources for steam generation:– Syngas radiant cooler

–

Carbonator– Hydrator

–

CO2

stream (HRSG)– H2

stream (firetube boiler and condensing heat exchanger)

Aspen Plus®

Modeling Results Calcium Looping Process vs. Conventional Process

Conventional Coal-to-H2


% Difference

Coal Feed Rate (tonne/h) 226 313 +38

O2 Consumptiona (tonne/h) 221 472 +114

Solid Waste (tonne/h) 23 137 +489

CO2 Sequestered (tonne/h) 469 741 +58

Net CO2 Emissions (tonne/h) 54 1 -98

H2 Production (tonne/h) 23 22 -6

Net Electric Power (MWe ) 31 254 +719

a95% (v/v) purity

Scale– For 1.3 Ca/C molar ratio, solids feed rate to calciner is 1705 tonne/h

(by comparison, coal feed rate to gasifier is only 226 tonne/h)– Ca/C ratio and solids circulation rate would be much larger without hydration– Significant capital cost and maintenance requirements associated

with handling this quantity of solids

Small particle size– Hydration results in micron-sized particles– Fluidization behavior needs to be confirmed at larger scale– Possible problems with thermophoresis

Heat transfer to/from solids– Use of gases as heat carriers– Fluidized beds with downstream particle separators

Effect of coal ash in calciner is uncertain

Concerns about erosion, plugging, scaling, etc.

Technical Challenges Solids Handling

High-temperature hydrator with heat recovery

Turboexpander with 65 bar inlet pressure

Flash calciner with oxyfuel combustion

High-pressure condensing heat exchanger for H2 stream

Very large, high-temperature lockhoppers

High-temperature (675°C) metallic filters with fine particles

Technical Challenges Unconventional / Unproven Equipment Items

Economic Analysis Key Assumptions

2008 U.S. dollarsCapacity factor = 90%Capital charge factor = 0.175O&M levelizing factors

– Coal = 1.25

–

Electricity = 1.19

–

General O&M = 1.18Variable O&M unit cost assumptions:

Coal $1.69 / GJElectric power $91.10 / MWhCO2 emission allowances $40.00 / tonneSolid waste disposal $17.71 / tonneLimestone $27.56 / tonneWater $0.12 / m3

Water treatment chemicals $0.37 / kgSelexol solution $3.55 / LShift catalyst $17.45 / LClaus catalyst $4.59 / L

Process Economic Summary Levelized Cost of Hydrogen ($/kg H2

)

Conventional Coal-to-H2


Capital $1.38

Fixed O&M $0.22 $0.30

Coal $0.55 $0.82

Variable O&M $0.04 $0.30

Credit – Net Difference in Electricity - -$1.11

Credit – Net Difference in CO2 Emissions - -$0.11

TOTAL $2.19 < $2.19

CLP Total Plant Cost must be < $1,959,000,000 to compete with conventional process

< $1.99

Next Steps Techno-Economic Evaluation

Determine the technical feasibility and capital cost of nonconventional equipment items

Optimize operating conditions for the carbonator, calciner, and hydrator

Optimize solid purge and make-up rates

Optimize heat integration

Evaluate sulfur management– Fate of sulfur in calciner– Trade-offs between extent of CaS oxidation in calciner, coal demand,

oxygen demand, and hydrogen production rate

Perform sensitivity analyses (e.g., prices, reactor conditions, solid purge rate) and study different plant configurations (e.g., IGCC)


Efficiently integrates the water-gas shift reaction and the removal of CO2, sulfur species, and halides into a single reactor for high-purity hydrogen production

Obviates the need for water-gas shift catalyst and excess steam

Hydration reverses the effect of sintering and maintains sorbent reactivity, permitting the use of a relatively low Ca/C molar ratio

Offers essentially zero CO2 emissions and significantly greater co-production of electricity than the conventional coal-to-hydrogen process, but at the expense of increased coal and oxygen consumption

Large solids handling requirement poses an operating and maintenance challenge

We are currently evaluating capital costs and the technical feasibility of unconventional equipment items (e.g., hydrator with heat recovery, high-pressure turboexpander) to determine the viability of the process

Documents

CALCIUM LOOPING PROCESS FOR CLEAN FOSSIL FUEL … septiembre/C27.pdf · Shwetha Ramkumar, Robert M. Statnick, Liang-Shih Fan William G. Lowrie Department of Chemical and Biomolecular