Low-Temperature Gasification of Biomass and Lignite: Consideration of Key Thermochemical Phenomena, Rearrangement of Reactions, and Reactor Configuration

Abstract

This paper discusses gasification of solid fuels, such as biomass and lignite, at temperatures well below 1000 °C, which potentially realizes a loss of chemical energy (LCE) smaller than 10% but encounters difficulty in fast and/or complete solid-to-gas conversion in conventional reactor systems. First, key thermochemical and catalytic phenomena are extracted from complex reactions involved in the gasification. These are interactions between intermediates (i.e., volatiles and char), catalysis of inherent and extraneous metallic species, and very fast steam gasification of nascent char. Second, some ways to control the key phenomena are proposed conceptually together with those to rearrange homogeneous/heterogeneous reactions in series/parallel. Third, implementation of the proposed concepts is discussed assuming different types of gasifiers consisting of a single-fluidized bed, dual-fluidized bed, triple-bed circulating fluidized bed, and/or fixed (moving) bed. The triple-fluidized bed can attain gasifica...