B. Özüm

Equilibrium calculations in coal gasification

Abstract Coal gasification is commercially important due to its application in ammonia, hydrogen, methanol and synthetic fuel production and in integrated gasification combined cycle (IGCC) power plants. Accurate process evaluations are required for the development of new generation gasification technologies. Perhaps the most crucial component of this evaluation is the accurate prediction of product gas quality for varying feed streams and operating conditions. Operating conditions such as reactor hydrodynamics, temperature and pressure are variables which differentiate the gasifiers that are being offered for commercial applications (fixed bed, fluid bed, entrained flow, dry or slurry feed, air or oxygen blown). The present work demonstrates that for reactive coal feedstocks and for gasifers operating at relatively high temperature and pressure (entrained flow and fluidized beds), product gas compositions can be estimated, regardless of gasifier type, using chemical equilibrium principles.

Coal gasification gas cleanup

Abstract Coal gasification integrated with combined cycle power generation (IGCC) is an alternative technology to utilize coal for electric power generation. IGCC technology has a higher efficiency and lower sulphur emissions than that of conventional power generation by coal combustion. Under gasification conditions, part of the coal S and N is converted to H2S and NH3, which have to be removed from the product gas before its combustion in the gas turbine. Sorbents can be used to capture H2S at the reactor temperature, or at a lower temperature after the product gas is partially cooled. Controlled combustion of coal gas can convert NH3 to N2. Equilibrium calculations provide valuable information on gas cleanup as a function of operating conditions of the selected gasifier technology and the type of sorbent being used.