Gasification

Gasification is a process that converts carbonaceous materials, such as coal or biomass, into carbon monoxide and hydrogen.

Related Topics:
Coal - Biomass - Carbon monoxide - Hydrogen

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In a gasifier, the carbonaceous material undergoes three processes. The pyrolysis process occurs as the carbonaceous particle heats up. Volatiles are released and char is produced, resulting in up to 70% weight loss for coal. The process is dependent on the properties of the carbonaceous material and determines the structure and composition of the char, which will then undergo gasification reactions. The combustion process occurs as the volatile products and some of the char reacts with oxygen to form carbon dioxide and carbon monoxide, which provides heat for the subsequent gasification reactions. Devolatilization and combustion are very rapid processes. The gasification process occurs as the char reacts with carbon dioxide and steam to produce carbon monoxide and hydrogen.

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The resulting gas is called producer gas or syngas (or wood gas when fueled by wood) and may be more efficiently converted to energy such as electricity than would be possible by direct combustion of the fuel, as the fuel is first combusted in a gas turbine and the heat is used to produce steam to drive a steam turbine. Also, corrosive ash elements such as chloride and potassium may be refined out by the gasification process, allowing high temperature combustion of the gas from otherwise problematic fuels.

Related Topics:
Producer gas - Syngas - Wood gas - Electricity - Combustion

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The gasification process was originally developed in the 1800s to produce town gas for lighting and cooking. Natural gas and electricity soon replaced town gas for these applications, but the gasification process has been utilised for the production of synthetic chemicals and fuels since the 1920s. It is now recognised that gasification has wider applications; in particular the production of electricity using IGCC, with the long-term aim of producing hydrogen for fuel cells. IGCC demonstration plants have been operating since the early 1970s and some of the plants constructed in the 1990s are now entering commercial service.

Related Topics:
Town gas - IGCC

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(Within the last few years gasification technologies have been developed that use also plastic-rich waste as a feed. In a plant in Germany such a technology - on large scale - converts plastic waste via producer gas into methanol. http://www.svz-gmbh.de http://www.tecpol.de)

Related Topics:
Plastic - Methanol

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Gasification relies on chemical processes at elevated temperatures >700°C, contrary to biological processes such as anaerobic fermentation (digestion) which produces biogas.

Related Topics:
Anaerobic - Fermentation - Digestion - Biogas

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Breakdown of hydrocarbons into syngas is done by carefully controlling the amount of oxygen present while heating the hydrocarbons to extreme temperatures.

Related Topics:
Hydrocarbon - Syngas

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