Gasification Technology

Abstract

Gasification is still an evolving technology, not only enabling the clean-up of fossil and biomass fuels for energy production, but also tackling issues associated with growing amounts of municipal solid waste, and providing a low cost fuel for a clean hydrogen economy. A history of gasifier development starts with the utilization of coal as an industrial fuel for process heat and lighting. The ability to produce synthetic gas (syngas) has made gasification an integral component in refinery operations and the production of chemicals. Renewable fuels such as biomass, municipal solid waste, and black liquor from pulp and paper industry are also suitable fuels for gasification. The chemistry and physics of conversion of these organic fuels includes pyrolysis, combustion, gasification, as well as mineral transformations. Integrated gasification and combined cycle processes are discussed with respect to electrical power production. The distinguishing features for different types of gasifiers are described including fixed bed, fluidized bed, and entrained flow gasifiers. More than 12 major gasifiers being marketed today together with several other novel gasifiers for treating biomass and municipal solid waste are described in terms of their main features and performance to produce high quality syngas (i.e., high content of carbon monoxide and hydrogen). The hydrodynamics and kinetics of each type gasifier are reviewed along with salient differences in their performance, such as syngas composition, when using a variety of fuels under different conditions. Critical operational features that are discussed include oxidizing media, air or oxygen blown; fuel feed stock; system pressure; and downstream clean-up. Successful application of gasifier technologies has required improved refractory materials to meet the most challenging gasifier environments. Thermal integration is becoming more critical to not only improving gasifier performance, but also gaining social acceptance for the responsible use of our dwindling fossil fuels. Gas clean-up is considered with respect to the removal of potential pollutants and the shifting to environmentally benign transportation and process fuels.