This document discusses coal gasification, which involves converting coal into a gaseous fuel called synthesis gas (syngas) through a process of partial oxidation. Syngas is composed primarily of carbon monoxide and hydrogen. There are three main types of gasifiers - moving bed, entrained flow, and fluidized bed. Catalytic gasification uses catalysts to lower operating temperatures and enhance reaction rates. Applications of syngas include power generation, chemical production, hydrogen production, and byproducts like ash for construction materials. Further research is needed to develop carbon capture technologies and more efficient oxygen separation methods to enable cleaner coal gasification processes.

1. Coal Gasification
Sagar Bharat
Integrated M.Sc. Chemistry

2. Contents:
 Introduction
 Reactions & Compositions
 Gasifiers
 Catalytic Gasification
 Applications
 Conclusions
 References
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3.  Introduction
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Gasification is a technological process that can convert any
carbonaceous raw material such as coal into fuel gas, also known as
synthesis gas (syngas).
Syngas is Composed primarily of the colorless, odorless, highly
flammable gases carbon monoxide (CO) and hydrogen (H2).
Gasification occurs in a gasifier, generally a high temperature/pressure
vessel where oxygen and steam are directly contacted with the coal
causing a series of chemical reactions to occur that convert the feed to
syngas and ash/slag.
Gasification is a partial oxidation process.

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5.  Reactions & Compositions
 In a gasifier, the carbonaceous feedstock undergoes several different
processes and/or reactions. Some of the major chemical reactions are :
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6.  The heat produced by the partial oxidation provides most of the
energy required to drive the endothermic gasification reactions.
 SYNGAS COMPOSITION-
 Can vary significantly depending on the feedstock and the
gasification process involved.
 However typically syngas is 30 - 60% carbon monoxide (CO), 25 -
30% hydrogen (H2), 0 - 5% methane (CH4), 5 - 15% carbon dioxide
(CO2).
 Plus a lesser or greater amount of water vapor, smaller amounts of
the sulfur compounds hydrogen sulfide (H2S), carbonyl sulfide (COS),
and finally some ammonia and other trace contaminants.
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7.  Gasifiers (Mainly 3 types)
 Counter-current flow of coal and oxidizing blast.
 Operate on lump coal.
 A top temperature of about 540°C and bottom
temperature of about 980°C & at a moderate
pressure(25-30 atms).
 Product gas at relatively low temperatures.
 High methane content in product gas.
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Lurgi Dry-Ash Gasifier
Coal
Ash
Rotating grate Crude gas
Steam &
oxygen
feeder
 Moving-bed gasifiers :
(e.g. Lurgi Dry-Ash gasifier)

8.  Entrained-flow gasifiers
(e.g. GE Energy gasifier)
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GE Enegy Glasifier
 Co-current flow of coal with the oxidant.
 High-temperature (1200 to 1500°C) slagging operation.
 Relatively large oxidant requirements.
 Carbon source is made of very fine particles in a
liquid or slurry for very good mass transfer.
 The syngas produced contains mostly hydrogen (H2)
and carbon monoxide (CO).

9.  Fluidized-bed gasifiers
(e.g. HTW gasifier)
• Can operate about 800 to 900°C & pressure can
be as high as 25 to 30 bar.
• Fuel flexibility, can gasify a wide range of
feedstocks.
• Good mixing between feed and oxidant, which
promotes both heat and mass transfer.
• The fine solid particles removed in the cyclone
are returned to the gasifier base to maximize
carbon conversion.
• Slagging will reduce fluidization, so temp remains
below softening point for ash.
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HT Winker gasifier system

10.  Catalytic Gasification
• Use of catalysts to lower gasifier operating temperatures & enhance the
rate of reactions.
• Alkali metal salts of weak acids (like potassium carbonate [K2CO3], sodium
carbonate [Na2CO3], potassium sulfide [K2S], and sodium sulfide [Na2S])
can catalyze steam gasification of coal.
• In the early 1970s, research confirmed that 10-20% by weight K2CO3 could
lower acceptable bituminous coal gasifier temperatures from 925°C to
700°C and that the catalyst could be introduced to the gasifier impregnated
on coal or char.
• Catalysts can also be used to favor or suppress the formation of certain
components in the syngas product.
• Disadvantages- Increase material cost for catalyst, catalysts can also be
diminished by poisoning.
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11.  Applications
• One of the most abundant energy sources.
• Can be used to produce ultra-clean fuel.
• Leading source of electricity today (IGCC).
• Chemical Production.( Methanol, ammonia, acetic acid etc)
• Hydrogen made from coal or other solid fuels can be used to refine oil, or to
make products such as ammonia and fertilizer (urea).
• By-product of burning (ash or slag ) can be used for concrete and roadways.
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12. Conclusions
 There are several challenges to using coal gasification to produce
hydrogen at target costs and with near-zero greenhouse gas
emissions. Additional R&D is needed to:
 Develop carbon capture, utilization, and storage technologies that
ensure minimal carbon dioxide is released in the production process.
 Develop new technologies that can replace the cryogenic process
currently used to separate the required oxygen from air.
 Particularly in clean generation of electricity from coal, gasification
may make an increasingly important part of the world's energy and
industrial markets.
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13.  References :
• Gasification,National Energy Technology Laboratory, U.S. DEPARTMENT OF ENERGY
https://www.netl.doe.gov/research/coal/energy-systems/gasification/gasifipedia/intro-to-
gasification
• Gasification Processes, Chris Higman, Maarten van der Burgt, 2 September 2007,
https://doi.org/10.1016/B978-075067707-3/50005-X
• Gasification System,
https://energy.gov/fe/science-innovation/clean-coal-research/gasification
• High Temperature Winkler (HTW) Coal Gasfiction – A Fully Developed Process For Methanol and
Electricity Production, by W. Renzenbrink; R. Wischnewski; J. Engelhard; and A. Mittelstadt,
Rheinbrawn
https://www.netl.doe.gov/File%20Library/research/coal/energy%20systems/gasification/gasifipe
dia/GTC9808P.pdf
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- Thank You -