| abstract |
Coal or other high ash containing carbonaceous solid fuel is reacted with a free-oxygen containing gas, with or without a temperature moderator, in a down-flow partial oxidation gas generator to produce a stream of raw synthesis gas, fuel gas, or reducing gas. A large portion of the combustion residue, i.e. molten slag and/or particulate solids that is entrained in the down-flowing generated gas stream is removed by gravity when the gas stream is passed through a diversion chamber. The main gas stream leaving the diversion chamber through the side outlet passes upward through a solids separation zone, optionally including gas-gas quench cooling, cyclones, filters, impingement separators, or combinations thereof. Next, most of the sensible heat in the gas stream is recovered by indirect heat exchange with boiler feed water and steam. Saturated and superheated steam are produced. In the main gas cooling zone, the hot gas stream with a substantially reduced solids content is passed serially through the tubes of two or more communicating shell-and-straight fire tube gas coolers. Saturated steam, which is produced in one, or more of said gas coolers, is superheated in another of said gas coolers. |