1 Coal Gasification Coal Gasification and the Meaning of Life and the Meaning of Life Edward S. Rubin Department of Engineering and Public Policy Carnegie Mellon University Pittsburgh, Pennsylvania Carnegie Mellon Electricity Industry Center Seminar April 22, 2003 Outline of Talk Outline 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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Coal Gasification Coal Gasification and the Meaning of Lifeand the Meaning of Life
Edward S. RubinDepartment of Engineering and Public Policy
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
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