Comparative study on the effects of wood dust and rice husk on wheat straw gasification process: Ash fusion characteristics and gasification reactivity

Abstract

• Different mechanisms of biomass type on enhancing AFTs of wheat straw are clarified. • Rice husk and wood dust show different impacts on mineral behaviours of wheat straw. • Higher rice husk ratio, lower reactivity. Higher wood dust ratio, higher reactivity. • Synergistic effect and decreasing activation energy are observed in two processes. The ash fusion characteristics and gasification reactivity of wheat straw (WS) blended with rice husk (RH) and wood dust (WD) were investigated, respectively. Furthermore, the transformation of minerals and synergy behaviour of gasification reactivity were explored. Results demonstrated that both RH and WD could enhance the ash fusion characteristic temperatures of WS, which were due to the increasing contents of higher melting-point compounds (quartz and tridymite in WS/RH mixtures, and Ca-silicates in WS/WD mixtures) and the decreasing contents of lower melting-point K-based compounds. Compared to pure WS, the deformation temperature of WS/RH mixture increased from 780 °C to 1233 °C at an RH ash ratio of 60%, and that of WS/WD mixture increased to 1065 °C at a WD ash ratio of 20%. Based on the appropriate ratio of WS, the gasification reactivity of WS increased with increasing WD ratios, whereas that of WS decreased with increasing RH ratios. Besides, the presence of synergistic effect and the reduction of activation energy were observed in two co-gasification processes.