Catalytic effects of simulated biomass ashes on coal gasification characteristics and the transformation evolution during gasification process

This paper focuses on the influence of key components in biomass ash on the gasification reactivity of coal by using simulated biomass ash. The migration patterns of typical biomass ash components and the structural evolution characteristics of coal during gasification process were deeply investigated. The results indicate that gasification temperature and Si element content are the key factors affecting gasification reactivity of coal. When the Si/K mass ratio is 0.5 and 1.0, gasification reactivity of the composite coal sample is stronger than that of raw coal, while the Si/K mass ratio is 1.5, gasification reactivity is weaker than that of raw coal. Under the experimental conditions, the composite coal sample with a Si/K mass ratio of 0.5 and a Ca/K mass ratio of 0.4 shows the strongest reactivity. The gasification reactivity index is 1.35 times higher than that of raw coal. Compared to potassium-containing minerals, calcium-containing minerals have stronger reactivity and are more likely to react with silicates to form calcium-containing silicates, such as calcium zeolites (CaO·Al2O3·2SiO2·4H2O), thereby avoiding the reaction between potassium-containing minerals and silicates to form non-catalytic minerals, which allows potassium to fully exert its catalytic effects. Dynamic analysis implies that shrinking core model well describes the gasification process of deashing coal catalyzed by simulated biomass ash. When the Si/K mass ratio is 0.5 and the Ca/K mass ratio is 0.4, the activation energy of composite coal sample is reduced to 174.39 kJ/mol, which is 14.32% lower than that of raw coal.