Chemical Looping Gasification

Fanxing Li and Liang-Shih Fan*

Department of Chemical and BiomolecularEngineering

The Ohio State University

Oct. 8th, 2008

Sulfur By-Product

Sulfur By-Product

Fly Ash By-Product

Fly Ash By-Product

Slag By-Product

Slag By-Product

Steigel and Ramezan, 2006 IGCC Efficiency: ~ 33% with CO2 control

Background: Coal Gasification Technology

Chemical Looping Gasification – Basic Concept

CO2

Reducer

CxHy

Metal Oxide

H2O

Metal

Oxidizer

H2O

H2

MeO + Fuel Me + CO2 + H2O

Me + H2O MeO + H2

Fe2O3

H2O H2

Fe

Air

Hot Spent AirCxHyOz

CO2 + H2O

Fe3O4

Sequestration

Syngas Chemical Looping (SCL) Concept

1. Reducer

2. Oxidizer

3. Combustor

To Steam Turbine

Coal

Candle Filter

Hot Gas Cleanup

Sulfur Byproduct

Oxidizer

CO2

Steam

H2 (450 PSI)

Hot Spent Air

O2

N2

Compressor

Gas Turbine Generator

Fe3O4

Fe

Fe2O3

BFW

Fly Ash

Raw Syngas

Compressor

Air

Reducer

Hot Syngas

Particle Makeup

Purge

Air

Com

bustor

BFWCO2

and Trace H2S, Hg

To Steam Turbine

Coal

Candle Filter

Hot Gas Cleanup

Sulfur Byproduct

Oxidizer

CO2

Steam

H2 (450 PSI)

Hot Spent Air

O2

N2

Compressor

Gas Turbine Generator

Fe3O4

Fe

Fe2O3

BFW

Fly Ash

Raw Syngas

Compressor

Air

Reducer

Hot Syngas

Particle Makeup

Purge

Air

Com

bustor

BFWCO2

and Trace H2S, Hg

Syngas Chemical Looping Process

Developed at OSUState-of-the-art

Oxygen Carrier Performance

Recyclability of Commercial Fe2O3

Iron Based Composite particles are completely recyclable for more than 100 cycles

Reduction Oxidation

Recyclability of Composite Fe2O3 Particles

PelletizationPellet Strength: Crushing Strength Test and

Dropping Test (ASTM D4179)

OSU Composite Pellets have significantly higher strength than commercial catalyst particles

COST: ~ $600/ton (2006 dollars)

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0.35

0.4

3.0 6.8 10.5 14.3 18.0 21.8 25.5 5.1Crushing Strength (MPa)

Freq

uenc

y

Fresh Pellet

Pellet after TwoRedox Cycles

Commercial WGSCatalyst Pellet

SCL Process Demonstrations

2.5 kWth Bench Scale Moving Bed

Light In Light Out

Gas In

Gas Out

Gas / solid

Sample Out

Temperature Measurement

Motor

Motor

Moving Bed Studies – Reducer Operation

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Axil Position (inch)

Solid

Con

vers

ion

(%)

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100

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Con

vers

ions

(%)

Solid H2 CO

Nearly 100% conversion of syngas achieved

Syngas Experiment (Reducer operation)

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-2 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32Distance from the bottom, inches

Solid

Con

vers

ion

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CH 4

Con

vers

ion

Solid (meassured)Solid (Calculated)CH4

CH4 Moving Bed Experiment (Liquid Fuel Synthesis test)

Nearly 100% conversion of CH4 achieved

Syngas, Methane, and Other Hydrocarbons Can be Fully Converted to CO2 and H2O in SCL Reducer

9999.199.299.399.499.599.699.799.899.9100

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Nom

aliz

ed H

2 Con

cent

ratio

n (%

)

Solid is fully regenerated to Fe3O4, H2 with an average purity of >99.95% is generated

Moving Bed Studies – Oxidizer Operation

Furn

ace Furnace

Fe3O4

Oven Temperature 1100 ºC

Particle temperature ~1200 ºC

AirAir

Spent Air

Significant temperature increase observed, particle found to be still reactive after being exposed under proposed combustor operating conditions (> 1200 ºC)

Demonstration of the Combustor

Fixed Bed Studies

Composite Particle Can Sustain 1200 ºC

Pellet Strength: Attrition Test

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0 1 2 3 4 5 6 7 8 9 10Number of Conveying Cycles

Perc

ent o

f Unb

roke

n Pe

llets

Pellets > 2 mm

Pellets >0.71 mm

Pellets >0.71 mm with 0.57% freshpellet makeup

0.57% fresh pellet makeup is sufficient

Collector

Gas Flow Meter

Valve

Gas Inlet

Pellets

Distributor

Filter

Riser

Dow

ner

0.3 m

ID: 1.96 cmOD: 2.5 cm

0.5 m2.7 m

2.0 m

Superficial Gas Velocity: v=18 m/s

Gas Outlet

Collector

Gas Flow Meter

Valve

Gas Inlet

Pellets

Distributor

Filter

Riser

Dow

ner

0.3 m

ID: 1.96 cmOD: 2.5 cm

0.5 m2.7 m

2.0 m

Superficial Gas Velocity: v=18 m/s

Gas Outlet

Simulation Studies

• A 1000 MWt (HHV) GE/Texaco is considered

• Carbon regulation mandates > 90% carbon captured

• The H2 coming out of the system is compressed to 30 atm for transportationwhile the CO2 is compressed to 2000 psi for geological sequestration

• No heat loss is assumed, heat can be integrated with a 100% efficiency

• The isentropic efficiencies is 0.83 for compressors, 0.86 for LP steam turbines, 0.88 for IP steam turbines, and 0.9 for gas turbines

• The energy consumption of PSA and sulfur removal units are provided by the low grade steam discharged from steam turbine

• Performance data obtained from bench scale unit is used for looping simulations

ASPEN® SimulationCommon Assumptions

Traditional Coal to Hydrogen Process

Assumption used is similar to those adopted by Mitretek Systems in their report to USDOE/NETL*.

* Gray D. and Tomlinson G. Hydrogen from Coal. Mitretek Technical Paper. DOE contract No:DE-AM26-99FT40465. (2002)

Syngas Chemical Looping Process

Practical factors that are taken into account in the simulation:

• Pressure drop of the major chemical looping units,

• Energy consumption for particle transportation

• Energy loss due to the purging of the particles

The simulation results represent a very conservative estimation of SCL performance based on current demonstration outcome

63.1252.6956.5Efficiency (%HHV)66.238.90Net Power (MW)

14.2412.3614.20Hydrogen (ton/hr)

1009090Carbon Captured (%)132.9132.9132.9Coal feed (ton/hr)

SCLConventional

Co-ProductionConventional Max H2

Comparison Between SCL and Traditional Coal to Hydrogen/Electricity Process

SCL process can increase the efficiency of State-of-the-art coal to hydrogen process by 7 – 10%

ASPEN® Simulation

Coal to Liquids Applications

Syngas Chemical Looping in CTL Applications

BFW

Coal Pretreatment

Candle Filter

Sulfur Byproduct

O2

N2

BFW

Fly Ash

Raw Syngas

Red

ucer

Oxi

dize

r

High Pressure

CO2

Air (Pneumatic Conveyor)

Steam

Pure H2

Fe

Fe2O3

Steam

Air

Warm Clean Syngas

H2/CO = 2:1

C1-C4 and Unconverted Syngas

Product Separation

C5 – C14

C17 and above

Hyd

rocr

ack

er

Cold Clean Syngas

H2/CO = 0.5

Separator IINaphtha

Diesel

Water

Generator

F-T Reactor

Heat Exchanger

Mercury Removal

Hg

SteamSpent Fe2O3 Powders

Fresh Fe2O3Pellets

Air

Steam

Steam

Com

bust

or

H2

Process (ASPEN) Simulations

Source: Noblis Systems

Liquid Fuel: 12,008 BBPD

Coal: 4,820 TPD

2.5 Bbl Fuel/Ton of Coal

Cleaning/Cooling

Gasification/Quench

BFW

H2Reactor

F-TReactor

H2/H2O

BFW

ProductSeparation

Gases

Upgrading

GasesNaptha 3,822Diesel 8,186

LP steam

HRSG

BFW

Dryer Compressed CO2

SteamTurbine 147.2 MW

FilterExpander

Water

15.5 MW

DepletedAir

HotH2O/CO2

SulfurPolish

FuelReactor

Depleted Air

H2O/CO2

Air

MP steam Steam

6

51 7 9

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2.4 MW Net 160.3 Plant162.7 MW

Cleaning/Cooling

Gasification/Quench

BFW

H2Reactor

F-TReactor

H2/H2O

BFW

ProductSeparation

Gases

Upgrading

GasesNaptha 3,822Diesel 8,186

LP steam

HRSG

BFW

Dryer Compressed CO2

SteamTurbine 147.2 MW

FilterExpander

Water

15.5 MW

DepletedAir

HotH2O/CO2

SulfurPolish

FuelReactor

Depleted Air

H2O/CO2

Air

MP steam Steam

6

51 7 9

8

12

11

16

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13 14

20

19

18

15

10

2.4 MW Net 160.3 Plant162.7 MW

Chemical Looping Process in a Coal-to-Liquids Configuration

DOE/NETL-2008/1307

Independent Assessment of the Potential of the Chemical Looping in the Context of a

Fischer-Tropsch Plant

Conclusions: Overall, the Chemical Looping system proposed by OSU has the potential to significantly (~10%) increase the yield of the state-of-the-art Cobalt based F-T process and allow more efficient heat recovery and much lower (~19%) carbon emissions.

Sub-pilot Scale Demonstrations

Reducer

Oxidizer

Combustor

Top

Section

Lower Middle

Section

Bottom

Section

Other Chemical Looping Gasification Processes

Coal-Direct Chemical Looping Process

Air Compressor

Expander

Coal

Ash/Spent Particle

H2

CO2

BFW

Steam

H2

CO2 + H2O

Fe2O3

Fe3O4

FeC

ombustor

Generator

Reducer

Oxidizer

H2S Remoal

Sulfur Byproduct

Hg Removal

Fe/FeO

Makeup Particle

Fe/FeO

Hot Spent Air

Fe2O3

Steam

N2

Air O2

Reducer Configuration

Coal (and O2)

Char gasification and particle reduction:

FeO + H2 Fe + H2OFeO + CO Fe + CO2

CO2 + C 2CO

Fe2O3

Coal devolatilisation:Coal → C + CxHy4

Particle reduction :CH4 + Fe2O3 → CO2 +

H2O + FeO

Fe

CO2 + H2O

Enhancer (H2, CO2, H2O)

Reaction Initiation:H2 + FeO Fe + H2OH2O + C → CO + H2

CO2 + C 2CO

2CO + 2FeOx 2FeOx-1 + 2CO2

1CO2

2CO2 + 2C 4CO

1 CO2

2 CO2

4CO + 4FeOx 4FeOx-1 + 4CO2 4 CO2

CO2 + C 2CO

2CO + 2FeOx 2FeOx-1 + 2CO2

1CO2

2CO2 + 2C 4CO

1 CO2

2 CO2

4CO + 4FeOx 4FeOx-1 + 4CO2 4 CO2

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

Calcium Looping ProcessHigh Purity Hydrogen Production

HeatOutput Heat

Input

Pure CO2 gas

Calcination: CaCO3 CaO + CO2

CO + H2O CO2 + H2

CaO + CO2 CaCO3

CaO + H2S CaS + H 2OCaO+ COS CaS + CO2

Chloride CaO + HCl CaCl2 + H2O

Syngas

Hydrogen

reactor

RegenerationReaction

HeatOutput Heat

Input

Pure CO2 gas

Calcination: CaCO3 CaO + CO2

WGSR : CO + H2O CO2 + H2

CO2 removal : CaO + CO2 CaCO3

Sulfur : CaO 2S CaS OCaO CaS + CO2

: CaO + HCl CaCl2 + H2O

Syngas

Hydrogen

Hydrogen reactor

CaCO3

CaO

Calciner

Use of metal oxide (CaO) in a reaction based capture/regeneration system

Carbonation: CaO + CO2 → CaCO3

Calcination: CaCO3 → CaO + CO2

Advantages of Carbonation/Calcination Reaction (CCR) Technology

Operation under flue gas conditions

High equilibrium capacities of sorbent

Use of sorbent can achieve low equilibrium CO2 concentrations

Regenerative cycle produces pure CO2 stream

CCR Process

CCR Process Demonstration

Concluding Remarks

0102030405060708090

0 20 40 60 80 100% Electricity

Ove

rall

Proc

ess

Effic

ienc

y

0102030405060708090

SCLGasfication-WGSIGCC-SELEXOLSubcritical MEAUltra-supercritical MEAUltra-Supercritical Chilled AmmoniaGasification H2 MembraneSyngas CLCCDCL

Comparison Among SCL, CDCL and Traditional Coal to Hydrogen/Electricity Processes

– Ohio Coal Development Office (OCDO) of the Ohio Air Quality Development Authority (OAQDA)

– USDOE

Acknowledgements

Questions ?