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

Abstract

The influence of key components in biomass ash on the gasification reactivity of coal, the migration patterns of typical biomass ash components and the structural evolution characteristics of coal during gasification process were deeply investigated by using a simulated biomass ash. The results indicate that gasification temperature and Si element content are the key factors affecting the gasification reactivity of coal. When the Si/K mass ratio is 0.5 and 1.0, the gasification reactivity of the composite coal sample is larger than that of raw coal, while the Si/K mass ratio is 1.5, the gasification reactivity is less 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 greatest reactivity. The gasification reactivity index is 1.35 times higher than that of raw coal. Compared to potassium-containing minerals, the calcium-containing minerals have stronger catalysis 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 the 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 gasification reaction activation energy of composite coal is reduced to 174.39 kJ/mol, which is 14.32% lower than that of raw coal.