Abstract

FUELS, SYNTHETIC, GASEOUS FUELS. Whereas coal continues to be a principal source of substitute natural gas, a more recently recognized source is petroleum. Coal can be converted to gas by several routes, but often a particular process is a combination of options chosen on the basis of the product desired, ie, low, medium, or high heat-value gas. Coal gas is the term applied to the mixture of gaseous constituents that are produced during the thermal decomposition of coal at temperatures in excess of 500°C, often in the absence of oxygen (air). A solid residue (coke, char), tars, and other liquids are also produced in the process.

Next to combustion, carbonization represents one of the largest uses of coal. Carbonization is essentially a process for the reproduction of a carbonaceous residue by thermal decomposition, accompanied by simultaneous removal of distillate, of organic substances. This process may also be referred to as destructive distillation. The gasification of coal is essentially the conversion of coal by any one of a variety of processes to produce combustible gases.