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Underground coal gasification (UCG) is an industrial gasification process, which is carried out in non-mined coal seams. It involves injection of a gaseous oxidizing agent, usually oxygen or air, and bringing the resulting product gas to the surface through production wells drilled from the surface.
The pyrolysis (or devolatilization) process occurs at around 200–300 °C. 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 process is used heavily in the chemical industry, for example, to produce ethylene, many forms of carbon, and other chemicals from petroleum, coal, and even wood, or to produce coke from coal. It is used also in the conversion of natural gas (primarily methane ) into hydrogen gas and solid carbon char, recently introduced on an industrial ...
Steam and carbon dioxide can also be used as the oxidants. As the metal oxide also serves as the heat transfer medium in the chemical looping process, the exergy efficiency of the reforming and gasification processes like that for the combustion process is also higher as compared to the conventional processes. [1] [2]
An integrated gasification combined cycle (IGCC) is a technology using a high pressure gasifier to turn coal and other carbon based fuels into pressurized gas—synthesis gas . It can then remove impurities from the syngas prior to the electricity generation cycle.
Underground coal gasification (UCG) is an industrial process which converts coal into product gas. UCG is an in-situ gasification process, carried out in non-mined coal seams using injection of oxidants and steam. The product gas is brought to the surface through production wells drilled from the surface. [1]
Gasification is the process of subjecting a feedstock to chemical reactions that produce gas. [10] [11] The first process used was the carbonization and partial pyrolysis of coal. The off gases liberated in the high-temperature carbonization of coal in coke ovens were collected, scrubbed and used as fuel.
Karrick Process, from U.S. Patent #1,958,918. The Karrick process is a low-temperature carbonization (LTC) and pyrolysis process of carbonaceous materials. Although primarily meant for coal carbonization, it also could be used for processing of oil shale, lignite or any carbonaceous materials.