Definition
The coal gasification is a technology that converts coal into a synthesis gas (or syngas) that can then be used to produce chemicals or other products.
The syngas produced from coal is also called “Town gas“.
The syngas is a mixture of carbon monoxide (CO), hydrogen (H2), carbon dioxide (CO2) and water vapour (H2O)
Comments
The syngas issued from coal is a combustible gas traditionally used as a source of energy for municipal lighting and heat before the advent of industrial-scale production of natural gas
The hydrogen obtained from the coal gasification can be used for multiple applications such as producing olefins or ammonia, that is called Coal-To-Chemical or Coal-To-Olefin, or used directly for powering a hydrogen power generation plant in upgrading fossil fuels.
Alternatively, the syngas can be converted into transportation fuels such as gasoline or diesel according to the Fischer-Tropsch process, that is called Coal-To-Liquid conversion.
During gasification process the coal is blown through with oxygen and steam while also being heated and pressurized.
During the reaction, oxygen and water molecules oxidize the coal and produce this gaseous mixture of carbon monoxide (CO), hydrogen (H2), carbon dioxide (CO2) and water vapour (H2O).
Some by-products may be obtain as well like tar, phenols, etc. ..
This process may also be conducted in-situ within natural coal seams, it is called Underground Coal Gasification (UCG).
The coal gasification had been well developped from mid 19th Century to the Second World War, but then the low prices of the other fossil fuels such oil and gas had turned off most of the coal gasification industry.
Today with the high price of the oil, above $80 per barrel and the gas in Asia above $18 per mmBTU, the coal gasification becomes again competitive, especially in countries like China and USA which have the world biggest coal resources and are the biggest energy consumers.
