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

Hydrogen production from fossil fuel and biomass feedstocks

Industrially, the main source of hydrogen is the synthesis gas derived from hydrocarbon fossil fuel and water. Depending on the actual application, the synthesis gas produced undergoes catalytic processing to optimise the hydrogen yield. It is frequently used in different gas mixtures; for instance, hydrogen/nitrogen mixtures for ammonia manufacture, hydrogen/carbon oxide mixtures for methanol production and Fischer-Tropsch synthesis of higher hydrocarbons. This chapter reviews the early development of large-scale coal-based hydrogen, before outlining modern technologies using hydrocarbon and biomass feedstocks. The catalytic steps that enhance the hydrogen yield and the various purification processes involved are also considered