Coal gasification is reviewed here to provide a foundation for more detailed discussion of biomass gasification.

A. Brief History

Coal gasification to produce gas for a variety of applications such as fuels, chemicals, and chemical intermediates has been known for many years. The largest application of coal gasification by far has been for manufactured fuel gas production by pyrolytic and partial oxidation processes in which the primary fuel components in the product gas are hydrogen, carbon monoxide, and methane. The first manufactured gas (town gas) plant was built in England in 1812 by London and Westminster Chartered Gas, Light and Coke Company, although the first record of experimental manufactured gas production from coal dates back to seventeenth-century England (cj. Environmental Research and Technology and Koppers Co., 1984; Srivastava, 1993). North America’s first manufactured gas plants were built in Baltimore in 1816, in Boston in 1822, and in New York in 1825 (Rhodes, 1974). The early processes involved the carbonization or destructive distillation of bituminous coal at temperatures of 600 to 800°C in small cast-iron retorts to yield “coal gas” (Villaume, 1984). It has been estimated that more than 1500 manufactured gas plants were in operation in the United States during the nineteenth century and the first half

“The standard enthalpies of formation used for the calculations are from Stull, Westrum, and Sinke (1987) and Daubert and Danner (1989). The standard enthalpy of formation of cellulose was calculated from its heat of combustion. The monomeric unit of cellulose is C6H10O5. The enthalpies are listed in kj/g-mol of monomeric unit gasified.

of the twentieth century. The gasification processes used in these plants af­forded water gas, producer gas, oil gas, coke oven gas, and blast furnace gas (Liebs, 1985; Remediation Technologies, Inc., 1990).

Natural gas displaced most manufactured gas for municipal distribution in industrialized countries after World War II. In the 1960s and 1970s, interest in developing advanced coal gasification processes was rekindled when it was believed that natural gas reserves would become insufficient in a few years to meet demand. This activity has since declined, but several coal gasification processes developed during this period have been commercialized and are used for production of fuel and synthesis gas.