Coal gasification is a thermochemical process that converts coal into synthesis gas (syngas), mainly consisting of hydrogen and carbon monoxide, through reactions with steam and oxygen under high temperatures and pressures. It allows for cleaner energy production and flexibility in feedstock utilization, and results in lower emissions compared to conventional combustion. Factors affecting gasification include temperature, pressure, gasifying agents, coal type, and gasifier design.

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Coal Gasification:
Characteristics & Factors
Affecting gasification
By
Er. T. AYISHA NAZIBA, Dr. D. RAMESH, Dr. S. PUGALENDHI

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Coal gasification
 Coal gasification is a thermochemical process that converts coal
into a synthesis gas (syngas) consisting mainly of hydrogen (H2)
and carbon monoxide (CO). This process involves reacting coal
with steam, oxygen, or a combination of both under high
temperatures and pressures. Coal gasification offers a versatile
method for producing clean energy, chemicals, and fuels from
coal.

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Characteristics of Coal Gasification

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Syngas Composition
 The primary products of coal gasification are hydrogen (H2) and
carbon monoxide (CO), along with other gases such as carbon
dioxide (CO2) and methane (CH4).
 Syngas composition depends on the type of coal, gasification
conditions (temperature, pressure, gasifying agent), and gasifier
design.
 .

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Cleaner Energy Production
 Coal gasification enables the production of cleaner energy
compared to conventional coal combustion.
 Syngas can be used directly for power generation in gas turbines
or fuel cells, or further processed into liquid fuels (e.g., methanol)
or chemicals.

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Feedstock Flexibility
 Coal gasification can utilize various types of coal, including low-
rank coals and coal wastes, as feedstock.
 It offers flexibility in sourcing feedstock and can be integrated with
carbon capture and storage (CCS) technologies for emissions
reduction.

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Reduced Environmental Impact
 Gasification of coal produces syngas with lower emissions of sulfur
dioxide (SO2), nitrogen oxides (NOx), and particulate matter
compared to coal combustion.
 It facilitates cleaner utilization of coal resources and contributes to
environmental sustainability

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Factors Affecting Coal Gasification

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Temperature and Pressure
 Higher temperatures and pressures enhance coal gasification rates
and affect the composition of syngas.
 Optimal temperature and pressure conditions depend on the
specific gasification process and desired syngas characteristics.

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Gasifying Agent
 The choice of gasifying agent (steam, oxygen, air, or a
combination) influences the gasification reactions and syngas
composition.
 Steam gasification promotes hydrogen production, while oxygen or
air gasification produces higher concentrations of carbon
monoxide.

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Coal Type and Properties
 The type of coal (anthracite, bituminous, sub-bituminous) and its
properties (moisture content, ash content, volatile matter) affect
gasification performance.
 Low-rank coals may require different gasification conditions
compared to high-rank coals.

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Gasifier Design and Operation
 Gasifier design (fixed-bed, fluidized bed, entrained flow) and
operating parameters (residence time, gasification rate) impact
the efficiency and effectiveness of coal gasification.
 Proper control of gasifier conditions is essential to optimize syngas
production and minimize by-products such as tar and char.

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