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New Technology for Trace Contaminant, Acid Gas Removal and Sulfur Recovery from Coal Gasification Syngas

Dennis Leppin, P.E., Gas Technology Institute,Des Plaines, Illinois, USA, PresentorRaj Palla, Shain Doong, Rachid Slimane, Howard Meyer,GTIScott Lynn, UC-Berkeley, Contributors

Presented at GTC 2005San Francisco, CAOctober 12, 2005

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Disclaimer> The work reported in what follows represents research from

numerous GTI researchers and subject matter experts and each of the 5 projects discussed can easily be a 20 min talk, so my apologies in advance for any oversimplifications and omissions and general lack of presentation of “data”

> More detailed presentations are available on most of these topics

> Contact me if interested

> Other relevant work is also underway at GTI which was omitted to make for a manageable presentation

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Introduction

> Syngas cleanup is complicated and expensive, but necessary

> Possibility of advancing the gasifier technology significantly may be moderate at this point

> GTI is working this issue on several fronts which will be briefly discussed in what follows

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Key Issues in Syngas Cleanup

> Trace contaminant removal> Hot Gas Cleanup> CO Shift and COS Hydrolysis> Bulk S removal> High CO2 to H2S acid gas treating

(selective removal requirement)> Low tonnage (<15-20 TPD) S recovery

where Claus is not feasible

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GTI Technology Developments

> UCSRP-HP Multi-Contaminant Removal> Morphysorb® Process> “Direct Oxidation” S and Hg

Removal/Recovery> “Ultra-Clean” Process> H2 Membrane Development

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Multi-Contaminant Removal Process (UCSRP-HP)

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UCSRP-HP Background

> Developed over a number of years by Scott Lynn, Prof. Emeritus at Univ. of CA, Berkeley. Regents issued lic. option to a private individual, who in turn licensed GTI

> GTI has conducted technoeconomicstudies for natural gas (in which applications a 40%benefit was estimated), bench-scale tests, and recently, tests with syngas

> DOE, ICCI and GTI now funding scale-up developments at GTI

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UCSRP – HP Basic Concept> Patented concept

> Solvent with high temperature stability and high SO2 and H2S solubility – DGM and related compounds

> Homogenous catalyst for Claus Reaction operates above sulfur melting point

> S combustion to produce SO2 which is then absorbed in solvent and cycled to absorber –remainder of S removed as product

> DEG loop to remove other contaminants

> Syngas delivered at well above S melting point by cross exchanger

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UCSRP-HP Applications:Treatment of Coal-Derived Syngas

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Research at GTI – High Pressure Lab Reactor

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UCSRP Lab Results

> Reactions occur with high rates> Solvent is stable (40 day test)> No unexpected corrosion results> Bright sulfur product> For syngas application – COS Hydrolysis

occurs at reactor conditions

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UCSRP Status

> DOE and ICCI funding further development at GTI

> GTI tests will include measurement of kinetics and mass transfer and contactor/separation issues and add’l. physical props measurements as well as IGCC reference case (with assistance of ConocoPhillips)

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Morphysorb

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Project Background> Originally started in 1972 to treat coal gasifier

effluents under A.G.A contract (1972-77)> Screened 108 solvents> Selected NFM as the best candidate> Project restarted in 1990 under GRI sponsorship and

later joined by USDOE> Uhde joined GTI team in 1996> Laboratory, pilot plant and scale-up studies

completed> Patented for natural and syngas treating in various

regions> The process is now commercially available as

Morphysorb exclusively through Uhde

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Morphysorb Process> What is it?

– Proprietary solvent/process(GTI and Uhde owns the technology)

– N- formyl morpholine/N-acetyl morpholine mixtures

> What is the application?– Bulk or trace removal of acid gas components – Subquality natural gas upgrading to either pipeline or LNG specification– Selective removal of H2S from natural/synthesis gas for generation of acid gas

stream suitable for Claus plant feed – Selective removal of H2S, CO2, COS, CS2, mercaptans and other components

from coal/oil gasification syngas at IGCC facilities

> Advantages– Higher solvent loading = lower circulation or higher throughput– Lower co-absorption of hydrocarbons (less losses)– Low corrosion, low environmental hazard– Low foaming potential– Low capital and operating costs

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Morphysorb Pilot Plant Test UnitPilot Plant Specifications– Pressure, 1200 psig

– Circulation Rate,35 gpm max.

– Feed Gas Flow Rates Up to 1.2 MMSCF/d

– Overall Dimensions,12 x 12 x 60 ft.

– To be relocated to FlexFuel in 2005

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Planned Mods to Flex-Fuel Facility

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Duke Energy’s Kwoen PlantWorld’s Largest AGI Facility

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Filter/Separator

Recycle Flash Drums

Absorbers 1st Stage Acid GasCompression

2nd to 4th StageAcid GasCompression

1st StageRecycle GasCompression

2nd StageRecycleGas Compression

Acid GasInjectionWell

Upgraded Sour Gas

Lean Morphysorb Acid Gas Flash Drums

Acid Gas

Kwoen Plant Process Flow Diagram

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First Commercial Application Brief Highlights—Duke Energy’s Kwoen Gas Plant (as of 2Q’05)

> The process is operating successfully without any solvent-related problems

> Processed over 200 Bcf of sour gas> ~17 Bcf of Acid Gas Injected (~30 MMSCFD)> Exceeded performance targets set forth in the

demonstration agreement> No corrosion related issues> Recent process modifications for high CO2 removal are

successful– Acid Gas Stream Composition (Prior to the changes)

> 85% H2S, 14% CO2 and 1% CH4

– Acid Gas Stream Composition (After process modifications)> 67% H2S, 30% CO2 and >2.5 % CH4

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Research Issues for Morphysorb Use for Syngas Treating> Define target specifications

> Performance Data

– Loading, Flash Gas rate, pickup H2S vs. CO2, partitioning of trace contaminants, optimum temperature,flash pressures, regen. conditions

> COS Hydrolysis – further quantification needed

> Experience needed with heated and/or vacuum regeneration

> Obtain solvent degradation data

> VLE data (K-values) on specific components of interest (we have

some but may not be at correct conditions)

> Piloting and Demonstration

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Morphysorb Summary> Commercial for Bulk Acid Gas Removal

– Several add’l. world-scale plants in various licensing stages

> Can be configured for various treating services, e.g., pure CO2 capture, LNG feed specs (50 ppmv CO2), natural gas treating (4 ppmv H2S) and syngas cleanup

> May have advantageous properties for syngas treating? Higher capacity?, COS hydrolysis, lower H2 absorption, lower eq’d. circ. Rates

> Further testing for syngas is warranted – not currently funded but some in-house research being carried out by Uhde GmbH and GTI.

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Direct Oxidation of H2S

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“DO” Concept

AIR

SYNGAS w/H2S

SULFUR

Direct Oxidation Reactor

Sulfur Condenser

DESULFURIZEDSYNGAS

AIR

SYNGAS w/H2S

SULFUR

Direct Oxidation Reactor

Sulfur Condenser

DESULFURIZEDSYNGAS

H2S + O2 S + H2O•Limits to amount of H2S that can be processed in a single-stage•Equilibrium conversion limits•Hg may be removed concomitantly along with elemental S•Various “Back-End” processes may be envisioned•Offerred Commercially by M-I SulfaTreat for Natural Gas cleanup

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CTU for High Pressure Operation

> CTU is rated for 800 psig operation

> Simulated gas blended via seven mass flow controllers

> CTU can be operated up to 700 ºF

> Equipped with State-of-the-art Analytical Systems

> Ambient Personal Monitors– H2S, SO2,LEL and CO

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CTU Simplified PFD

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DO Research Status> Increasing the oxygen:hydrogen sulfide ratio above the stoichiometric level of

0.5 (for the reaction of hydrogen sulfide to elemental sulfur) does improve the conversion of hydrogen sulfide and the yield of elemental sulfur, without causing significant undesirable reactions of oxygen. The conversion rates are in the range of 58 to 69%.

> The benefits of increased oxygen in the feed diminish, as the O2:H2S ratio is increased beyond about 0.75.

> Very little oxidation of either carbon monoxide or hydrogen (the valuable components of the syngas) was apparent in any of the test conditions of the experiments; most of the oxygen consumed in the feed could be accounted for by the direct oxidation of the feed hydrogen sulfide.

> Very little oxidation of either carbon monoxide or hydrogen (the valuable components of the syngas) was apparent in any of the test conditions of these experiments. In these experiments, although the primary product of the direct oxidation of hydrogen sulfide was elemental sulfur, there was some amount of carbonyl sulfide formed.

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Ultra-Clean Process

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Sorbent Fines

Ultra-Clean Syngas

SyngasCooler

Sulfur & Halide Bulk Removal

System

SorbentsMakeup and

Disposal

SorbentFines

Injection

SorbentFines

Injection

RawSyngas

Sorbent Fines& Char

RecoveredSulfur Stage I

Filter -ReactorStage II

Filter -ReactorGasifier

Cyclone

RawFuel Gas

Bedchar/sorbent

Cyclonechar/sorbent

Steam

Oxidant

Coal, Biomass, OtherCarbonaceous Fuels

Limestonesorbent

Novel Gas Cleaning Process Concept: Use an existing particulate control device (barrier filter) as a chemical reactor for multi-pollutant control at hot/warm temperatures

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PCD’s as Barrier Filter-ReactorsBarrier filters applied as semi-continuous

packed-bed reactors for simultaneous control of particulates and gaseous contaminants

Dry ProcessAvoids fuel gas condensation

Coupling efficient particle capture with an effective entrained/filter cake reaction environment

Multiple contaminants can be simultaneously controlled in a single filter-reactor vessel (S, halide, and Hg compounds)

Potential to incorporate capability to control other contaminants (ammonia, trace metals (As, Se, Cd))

Process uses powdered sorbent particles with very high specific surface area

No need for highly porous support structureNo need for special particle attrition

resistance

Low-cost

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Pilot Test Facility Configuration

Direct Spray Quench Trona Sorbent

Feeder

Conditioning Filter-Reactor (Stage I)

CF-R Let-down Hopper

Stage II de-Cl Sorbent FeederStage II de-S

Sorbent Feeder

Test Filter-Reactor (Stage II)

Sulfur Guard Bed

SGB Pre-heater

Trim Cooler By-pass & UCP Pressure Control Systems

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Sorbent Injection Systems

Pressurized ShellLoading

Nozzle

Feed Hopper

Weigh Cells

Feeder

Discharge

Stage II de-S & de-Cl Sorbent Feed Systems

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Pilot Test Facility Configuration Showing Sampling Points for

Solids, Liquids, and Gases

S-13C

S-19

S-8A

G-14E

26A

26B

Trim Cooler

14B

S15A

G24

G7

25A

G14

S25S7D

S7E

S7F

14D

16A

16B

L14E

G14A

L8A13B

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S7C

G7B

G7A

11

G20

13A

G19

25B

S21

S18

S12

10

S9

S54

S6

3

S15B

Low-sulfurCoal

N2

N2

N2

GasifierAsh

Air orOxygen

Steam

N2

N2

Dust

CWS

CWR

Stage IHalideSorbent

Stage IISulfur Sorbent

Particulates/Spent Trona

SpentSorbents

Dust

FlueGas

GASIFIER

PrimaryCyclone

SecondaryCyclone

DirectSprayQuench

Flare GasCyclone

Flare

Cond.Filter-Reactor

TestFilter-Reactor

SulfurGuardBed

S1

2

G8

G13

17 22

14C

CWS

Stage IIHalide Sorbent

N2

Condensate

Condensate

Gasification Syngas Conditioning(Ultra-Clean Process Stage I Testing)

Ultra-Clean Process Testing(Stage II)

S-13C

S-19

S-8A

G-14E

26A

26B

Trim Cooler

14B

S15A

G24

G7

25A

G14

S25S7D

S7E

S7F

14D

16A

16B

L14E

G14A

L8A13B

23

S7C

G7B

G7A

11

G20

13A

G19

25B

S21

S18

S12

10

S9

S54

S6

3

S15B

Low-sulfurCoal

N2

N2

N2

GasifierAsh

Air orOxygen

Steam

N2

N2

Dust

CWS

CWR

Stage IHalideSorbent

Stage IISulfur Sorbent

Particulates/Spent Trona

SpentSorbents

Dust

FlueGas

GASIFIER

PrimaryCyclone

SecondaryCyclone

DirectSprayQuench

Flare GasCyclone

Flare

Cond.Filter-Reactor

TestFilter-Reactor

SulfurGuardBed

S1

2

G8

G13

17 22

14C

CWS

Stage IIHalide Sorbent

N2

Condensate

Condensate

Gasification Syngas Conditioning(Ultra-Clean Process Stage I Testing)

Ultra-Clean Process Testing(Stage II)

26A

26B

Trim Cooler

14B

S15A

G24

G7

25A

G14

S25S7D

S7E

S7F

14D

16A

16B

L14E

G14A

L8A13B

23

S7C

G7B

G7A

11

G20

13A

G19

25B

S21

S18

S12

10

S9

S54

S6

3

S15B

26A

26B

Trim Cooler

14B

S15A

G24

G7

25A

G14

S25S7D

S7E

S7F

14D

16A

16B

L14E

G14A

L8A13B

23

S7C

G7B

G7A

11

G20

13A

G19

25B

S21

S18

S12

10

S9

S54

S6

3

S15B

Low-sulfurCoal

N2

N2

N2

GasifierAsh

Air orOxygen

Steam

N2

N2

Dust

CWS

CWR

Stage IHalideSorbent

Stage IISulfur Sorbent

Particulates/Spent Trona

SpentSorbents

Dust

FlueGas

GASIFIER

PrimaryCyclone

SecondaryCyclone

DirectSprayQuench

Flare GasCyclone

Flare

Cond.Filter-Reactor

TestFilter-Reactor

SulfurGuardBed

S1

2

G8

G13

17 22

14C

CWS

Stage IIHalide Sorbent

N2

Condensate

Condensate

Gasification Syngas Conditioning(Ultra-Clean Process Stage I Testing)

Ultra-Clean Process Testing(Stage II)

Low-sulfurCoal

N2

N2

N2

GasifierAsh

Air orOxygen

Steam

N2

N2

Dust

CWS

CWR

Stage IHalideSorbent

Stage IISulfur Sorbent

Particulates/Spent Trona

SpentSorbents

Dust

FlueGas

GASIFIER

PrimaryCyclone

SecondaryCyclone

DirectSprayQuench

Flare GasCyclone

Flare

Cond.Filter-Reactor

TestFilter-Reactor

SulfurGuardBed

S1

2

G8

G13

17 22

14C

CWS

Stage IIHalide Sorbent

N2

Condensate

Condensate

Gasification Syngas Conditioning(Ultra-Clean Process Stage I Testing)

Ultra-Clean Process Testing(Stage II)

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Analytical Equipment for Ultra-Clean Testing

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H2 Membrane Process

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H2 Membrane ConceptConventional gasifier

Gasifier

Gas cleaning Shift reaction

H2 separationcoal

Oxygen steam hydrogen

Membrane gasification reactor

Gasifier

membrane

hydrogen

Gas

cleaning

CO2removal

CO2

Power generation

coal

Oxygensteam

Research Funded by NETL/ICCI/AEP

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GTI High Temperature/High Pressure Permeation Unit

hydrogen

Inertsweeping

gas

membrane

Cylindricalheater

non-permeate

permeate

Inner tube

Outer tube

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Potential Benefits of Membrane Reactor for Hydrogen Production from Coal> High H2 production efficiency:

– Thermodynamic analysis and recent modeling work indicate over 30 - 50% improvement in H2 production efficiency over the current gasification technologies

> Low cost: – reduce/eliminate downstream processing steps

> Clean product:– no further conditioning needed, pure hydrogen

> CO2 sequestration ready: – simplify CO2 capture process

> Power co-generation: – utilization of non-permeable coal syngas

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Proton-Conducting Membranes Identified as Leading Candidate Materials> Perovskite membranes evaluated:

– BaCe0.9Nd0.1O3-α (BCN)(supported or unsupported)

– BaCe0.8Y0.2O3-α (BCY)– SrCe1-xEuxO3-α (SCE)– SrCe0.95Tm0.05O3-α (SCTm)

Membrane Fabrication

> Die pressing or tape casting for self supporting membranes

> Supported membrane: same material for both porous and dense layers

Hydrogen at high pressure e-

e-

H+

Mixed proton/electron conducting membrane

H2 2H+ +2e- 2H+ +2e- H2 H+

Hydrogen at low pressure

Hydrogen at high pressure e-

e-

H+

Mixed proton/electron conducting membrane

H2 2H+ +2e- 2H+ +2e- H2 H+

Hydrogen at low pressure

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Some Experimental Results

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0 2 4 6 8 10 12 14H2 feed pressure, bar

H2

flux,

STP

CC

/min

/cm

2

950C

900C

50/50 H2/He feed, 900C

BCN, unsupported0.2 mm

0.5

0.55

0.6

0.65

0.7

0.75

0 50 100 150 200 250 300time, hr

H2 fl

ux, c

c/m

in/c

m2

980

1000

1020

1040

1060

1080

1100

Tem

p, C

fluxtemp

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

0 2 4 6 8 10 12 14Feed H2 Pressure, atm

H2

flux,

STP

CC

/min

/cm

2

100% H2P=8.14 atm, with He60% H2P=1 atm, with He100%H2, 2nd sample

SCTm 1.7 mm950C

0

0.1

0.2

0.3

0.4

0.5

0.6

0 2 4 6 8 10 12 14H2 feed Pressure, bar

H2

flux,

STP

CC

/min

/cm

2

100% H2P=7.8 atm with He

BCN, supported0.2 mm 950C

H2 Flux for SCTm membranes

H2 Flux for BCN membranes

Stability Testing (pure H2)

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H2 Membrane Status> Several barium/strontium cerate-based perovskite

membranes show reasonable hydrogen flux at gasification temperatures

> Hydrogen flux increases with pressure (to about 4 bar) and temperature

> Conceptual design showed that a membrane module could be configured within a fluidized bed gasifier without a substantial increase of the gasifier dimensions

> Identified Zr-doped perovskite membranes as potential materials for further testing with respect to the chemical stability issues in the coal-derived syngas environment

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CONCLUSIONS> A robust R&D program is underway with gov’t.

and industry sponsorship – many difficult and challenging issues need to be addressed

> Several key issues of syngas cleanup are being addressed

> Significant cost reductions in a variety of applications are possible

> GTI has developed flexible facilities for conduct of syngas-related research

> Stay tuned for developments and your participation in licensing, utilization of results, offering host sites, or other financial participation would be most welcome

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For Detailed Further Information

> Contact Vann Bush or Dennis Leppin at GTI

Vann.Bush@gastechnology.orgDennis.Leppin@gastechnology.org

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Thank You

> For staying around for the last paper and please have a safe journey home