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Coal Gasification Coal Gasification and the Meaning of Lifeand the Meaning of Life

Edward S. RubinDepartment of Engineering and Public Policy

Carnegie Mellon UniversityPittsburgh, Pennsylvania

Carnegie Mellon Electricity Industry Center Seminar

April 22, 2003

Outline of TalkOutline of Talk

• What is coal gasification?• How does it work?• Why the interest?• Where does it stand?• Where is it headed?

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What is Coal?What is Coal?

Carbon (wt%) 61.2Hydrogen 4.20Oxygen 6.02Sulfur 3.25Nitrogen 1.16Chlorine 0.17Ash 11.0Moisture 13.0Mercury (ppm,dry) 0.12HHV (Btu/lb) 10,900

47.93.4010.80.480.620.036.4030.40.10

8,335

Bituminous Subbituminous(Ill.#6) (PRB)

Coal vs. Other Fossil FuelsCoal vs. Other Fossil Fuels

COALCOAL C:H ~ 1:1 C H

PETROLEUMPETROLEUM C:H ~ 1:2 C HH

NATURAL GASNATURAL GAS C:H ~ 1:4 C HHHH

H+ = synthetic oil

H H+ = synthetic NG

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What Is Gasification?What Is Gasification?

• Gasification is a process that converts carbonaceous materials, such as fossil fuels and biomass, into mixtures of hydrogen and carbon monoxide (called synthesis gas, or syngas)

• Other gaseous species also are formed in varying amounts, depending on the fuel composition and process conditions

• The syngas can be burned as a fuel, or processed to produce chemicals and other fuels

• While the focus of this talk is on coal gasification, an important attractions of this technology is that it can process other materials besides coal

Gasification BasicsGasification Basics

• Coal gasification must be carried out at high temperature (and pressure, usually) to first decompose the coal then create new products (via addition of hydrogen)

• The source of heat for these reactions is the partial oxidation (combustion) of the coal (requiring some addition of oxygen)

• The most abundant source of hydrogen is water (H2O), added either as a liquid or vapor (steam)

• The source of oxygen is either air or nearly-pure oxygen (supplied by an air separation unit)

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A Typical Coal GasifierA Typical Coal Gasifier

CoalCoal%C, H, S, O, N, %C, H, S, O, N, ClCl%Ash%Ash

HydrogenHydrogenHH22OO

OxygenOxygenAir or OAir or O22

Syngas (raw)Syngas (raw)% CO% CO% H% H22

% CO% CO22

% H% H22OO% CH% CH44

% COS% COS% H% H22SS% HCl% HCl% NH% NH33

% N% N22% Ash% Ash

SlagSlag

Gasification processes use one or more common reactions:

Reaction with oxygen (partial oxidation)HC + O = H2 + CO + heat

Reaction with steam (reforming)HC + H2O + heat = 3/2H2 + CO

Thermal decompositionHC + heat = H2 + C + organics

Reaction with hydrogen (hydrogasification)HC + H2 = CH4 + heat

Gasification ChemistryGasification Chemistry

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Uses of SyngasUses of Syngas

• Electric power generation• Steam generation• Process heat• Chemicals production• Liquid fuels production• All of the above

After cleanup for removal of impurities, syngas can be used for:

Texaco Gasification ProcessTexaco Gasification Process

Syngas

End-productsFeeds Gas RefiningOxygen

Electricity

SulfurSolids

Gasification

SULFURRECOVERY

Co-products:

H2S

HRSG Steam

Combustion Turbine

SyngasAlternatives:

Syngas

CO2

• Hydrogen• Chemicals• Ammonia• Fuel Cells• Fischer-

Tropsch

• Natural Gas

• Any Oil

• Tar/Asphalt

• Petroleum Coke

• Coal

• Wastes/by-Products

• Biomass

GASSEPARATION

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CO + HCO + H22

Acetic Acid

Ethene & PropeneAcetic Anhydride VAM

n-Butyl AcetateTerephthalic Acidn-Butylenep-Xylene

MethanolMethanolMTBE FormaldehydeIsobutylene

Gasoline & FuelsGasoline & Fuels

Lubricants & Lubricants & WaxWax

Ethanol & IsobutanolEthanol & Isobutanol

SNGSNG

HydrogenHydrogen

MDIMDIAniline

Phosgene

1,4-Butanediol

Acetylene

Ammonium SulphateAmmonium Sulphate

AmmoniaAmmoniaPhosphoric AcidAmmonium Phosphate & Ammonium Phosphate & Diammonium PhosphateDiammonium Phosphate

Sulphuric Acid

UreaUreaAmmonium NitrateAmmonium Nitrate

Nitric AcidNitric Acid

Source: Gunal-Akgol, U.Waterloo

Chemicals and Fuels from SyngasChemicals and Fuels from Syngas

An Old TechnologyAn Old Technology

• Coal gas was first used in London in 1790 for gas lights

• Later used for fuel gas in Europe and North America in the 19th and early 20th century

• Used to produce coal-derived transportation fuels in Germany during WWII

• Many different gasification processes have been proposed, employing different schemes for fuel feed, reactor design, etc.

• Current generation of gasifiers are cleaner and more efficient than earlier designs

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A 1942 view of coal gasification

. . . from John Wayne and friends

Byproduct Coke Plant Byproduct Coke Plant (World(World’’s Biggest, ca. 1970)s Biggest, ca. 1970)

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Why the Current Interest?Why the Current Interest?

• Gasification is already commercially attractive for a variety of refinery and petrochemical processes

• Offers a way to utilize low-value products or wastes as “opportunity fuels” (esp. petroleum coke)

• Can produce multiple products (polygeneration)

Worldwide Gasification CapacityWorldwide Gasification Capacity

Source: SFA Pacific /DOE, 2001

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Gasification by Global RegionGasification by Global Region

Source: SFA Pacific /DOE, 2001

Largest Gasification ProjectsLargest Gasification Projects

Source: SFA Pacific /DOE, 2001

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Gasifier TechnologiesGasifier Technologies

Source: SFA Pacific /DOE, 2001

Primary Gasification FeedstockPrimary Gasification Feedstock

Source: SFA Pacific /DOE, 2001

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Gasification ApplicationsGasification Applications

Source: SFA Pacific /DOE, 2001

Source: Chevron-Texaco

Pet Coke Gasification to H2 and CO2 for Ammonia and Urea

Farmland Industries, Coffeyville, Kansas

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Pet Coke Gasification to H2 and CO2 for Ammonia and Urea

Farmland Industries, Coffeyville, Kansas

Regina

Bismarck

North Dakota

Saskatchewan CanadaUSA

WeyburnWeyburn

COCO22

Regina

Bismarck

North Dakota

Saskatchewan CanadaUSA

WeyburnWeyburn

COCO22

SNG Plant Supplying CO2 for Enhanced Oil Recovery (EOR) and

Sequestration

Dakota Coal Gasification Plant

Sources: USDOE; NRDC

EOR at Weyburn

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Why the Current Interest?Why the Current Interest?

• Gasification is already commercially attractive for a variety of refinery and petrochemical processes

• Offers a way to utilize low-value products or wastes as “opportunity fuels” (esp. petroleum coke)

• Can produce multiple products (polygeneration)• In the U.S., great interest today is in the potential for

IGCC power plants to meet stringent air emission standards — especially future CO2 capture and storage reqmts — at lower cost than combustion-based plants

Fate of ImpuritiesFate of Impurities

Coal Combustion Systems• Sulfur SO2• Nitrogen NO + NO2• Ash (Bottom Ash) + Flyash

Coal Gasification Systems• Sulfur H2S (+COS)• Nitrogen NH3• Ash Slag (+ Fines)

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PC Plant with COPC Plant with CO22 CaptureCapture

IGCC Plant with COIGCC Plant with CO22 CaptureCapture

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A Modern Gas Turbine

Integrated Coal Gasification Combined Cycle (IGCC) Plant

Wabash River, Indiana

Source: Global Energy, 2002

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Polk Power StationIGCC Plant

(Tampa Electric, 250 MW)

EPRI Cost and Performance EstimatesEPRI Cost and Performance Estimates(without CO(without CO22 capture)capture)

Note: Hg removal adds ~2-3$/MWh to PC and 0.3$/MWh to IGCC COE.

Technology SubPC SuperPC UltraPC AFBC IGCC NGCC

MW 500 500 500 500 590 506

Capital ($/kW) 1364 1397 1416 1426 1502 500

HHV Heat Rate 10,070 9550 9402 10,024 8891 7646(kJ/kWh)

Fuel ($/GJ) 0.948 0.948 0.948 0.948 0.948 2.50/3.71/2.50

Capacity Factor (%) 80 80 80 80 80 80/80/40

COE ($/MWh)Capital 24.0 24.6 24.9 25.1 26.5 8.8O+M 6.8 6.7 6.7 8.9 7.2 3.2Fuel 9.5 9.0 8.8 9.7 8.4 19.1Total 40.3 40.3 40.5 43.7 42.1 31.1/40.3/41.9

Source: Holt, 2002

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Cost of Alternative OptionsCost of Alternative Options

0

20

40

60

80

100

120

0 100 200 300 400 500 600 700 800 900 1000

Cos

t of E

lect

ricity

($ /

MW

h)

PC

CO2 Emission Rate (kg / MWh)

IGCC

Coal Plants(combustion,gasification)

Wind, Biomass

Nuclear,Hydro

Natural GasCombined Cycle

Coal and GasPlants with

CO2 Capture

Gasification vs. CombustionGasification vs. Combustion

• A Chemistry Perspective:Combustion = Oxidizing atmosphereGasification = Reduction atmosphere

• A Disciplinary Perspective:Combustion = Mechanical EngineeringGasification = Chemical Engineering

• A Technology Perspective:Combustion = Power Plants Gasification = Chemical Plants, Refineries, etc.

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Where Do We Go from Here?Where Do We Go from Here?