Numerical simulation of CPFD for 16 t/h circulating fluidized bed biomass gasification

This study employed computational particle flow dynamics (CPFD) methodology to construct a three-dimensional numerical model of a 16 t/h circulating fluidized bed gasifier using a mixture of woody biomass and straw biomass as feedstock. The model captured the distribution patterns of flow fields, temperature fields, and gas composition within the furnace, enabling an in-depth analysis of how different equivalence ratio (ER) influence gasification characteristics. Numerical simulation results indicate that as the equivalence ratio increases from 0.25 to 0.35, the molar fraction of combustible gas decreases from 38.70 % to 28.98 %, while the lower heating value (LHV) and gasification efficiency decline from 5.06 MJ/Nm 3 and 77.29 % to 3.72 MJ/Nm 3 and 61.24 %, respectively. The study further revealed that as the ER increases, gas composition and gasification reaction rates exhibit distinct non-uniform distributions across different heights within the riser. Analysis of key reaction rate variations elucidated the governing patterns of gas component consumption and generation by steam methane reforming (SMR) and Boudouard reactions at different riser height intervals, clarifying the control mechanisms of reaction rates at various riser locations. These findings provide crucial theoretical foundations and numerical simulation bases for deepening the understanding of multiple biomass gasification reaction mechanisms in large-scale circulating fluidized beds and optimizing system design.