COAL AND BIOMASS GASIFICATION FOR SNG PRODUCTION

Within the production of synthetic natural gas - basically methane-from solid feed stock such as coal or biomass the major conversion step is gasification, generating a product gas containing a mixture of permanent and condensable gases, as well as solid residues. The gasification step can be conducted in different atmospheres and using different reaction agents. This chapter discusses the role of gasification for the overall substitute natural gas (SNG) process, and the basic thermodynamic aspects within gasification. The gasification process is a series of different conversions involving both homogeneous and heterogeneous reactions. The basic steps from solid fuel to product gas are drying, pyrolysis, and gasification. From a technological viewpoint, there basically exist three different gasification reactor types that are used at large scale: fixed bed reactors, entrained flow reactors, and fluidized bed reactors. Coal is mainly used in entrained flow gasification or fixed bed units, whereas biomass gasification is mostly done in fluidized bed reactors. \ua9 2016 by John Wiley & Sons, Inc. All rights reserved