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In industrial chemistry, coal gasification is the process of producing syngas—a mixture consisting primarily of carbon monoxide (CO), hydrogen (H 2), carbon dioxide (CO 2), methane (CH 4), and water vapour (H 2 O)—from coal and water, air and/or oxygen. Historically, coal was gasified to produce coal gas, also known as "town gas".
Below is a schematic flow diagram of an IGCC plant: Block diagram of IGCC power plant, which utilizes the HRSG. The gasification process can produce syngas from a wide variety of carbon-containing feedstocks, such as high-sulfur coal, heavy petroleum residues, and biomass.
Syngas produced by coal gasification generally is a mixture of 30 to 60% carbon monoxide, 25 to 30% hydrogen, 5 to 15% carbon dioxide, and 0 to 5% methane. It also contains lesser amount of other gases. [10] Syngas has less than half the energy density of natural gas. [11]
The syngas production can lead to the hydrogen production from the downstream water-gas shift reaction. The CLG process can also be applied to electricity generation, resembling the IGCC based on the syngas generated from the chemical looping processes.
The Fischer–Tropsch process (FT) is a collection of chemical reactions that converts a mixture of carbon monoxide and hydrogen, known as syngas, into liquid hydrocarbons. These reactions occur in the presence of metal catalysts , typically at temperatures of 150–300 °C (302–572 °F) and pressures of one to several tens of atmospheres.
Multiple types of solid fuel gasifiers are commercially available for coal, petcoke, and biomass gasification.Designs vary depending on fuel and intended application. As a result, they can differ in the composition of the syngas produced and the efficiency with which they convert coal energy content to syngas energy content - a performance parameter typically termed cold gas efficiency. [3]
Syngas may also be used as the hydrogen source in fuel cells, however the syngas produced by most gasification systems requires additional processing and reforming to remove the contaminants and other gases such as CO and CO 2 to be suitable for low-temperature fuel cell use, but high-temperature solid oxide fuel cells are capable of directly ...
Known as the Eastman Integrated Coal Gasification facility, it first opened in 1983 and is designed to process syngas from the gasification of Southwest Virginia and Eastern Kentucky coal, using Texaco gasifiers (now GE gasifier technology [15]). The intermediate products of syngas conversion are methanol and CO; these are further converted ...