Thermodynamic modelling of fate and removal of alkali species and sour gases from biomass gasification for production of biofuels

摘要

The development of advanced synthesis gas cleaning technologies based on chemical conversion and physical separation can improve the efficiency of gasification processes for production of biofuels. This paper outlines thermodynamic equilibrium calculations on the release and removal of alkali species and sour gases during gasification of 24 different types of herbaceous and woody biomass under the conditions of the gasifier in Güssing, Austria. In general, the calculation results are in good agreement with former experimental results. The composition of the gasifier derived as well as the cleaned gas strongly depends on the used feedstock. The alkali concentration can be limited to values below 100 ppbv using aluminosilicates at 850 °C. The H_2S concentration cannot be limited to values below 200 ppmv using conventional Ca- or Cu-based sorbents but can be limited to values below 1 ppmv by stabilised BaO at 850 °C. The HC1 concentration can be limited to values below 1 ppmv by alkali carbonates at temperatures below 550 °C.