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建立生物质鼓泡流化床气化过程的动力学三维数理模型,气相采用k-ε湍流模型,固相采用基于颗粒动理学理论封闭模型,并自编化学反应子模型。研究了气化炉内固相体积分数、各相的速度以及气化产物的组分的分布,并预测了水蒸气与生物质质量比(S/B)对气化的影响。在鼓泡床的下段固相和气相的速度均呈现振荡变化,特别是在床高H=0.18 m处,由于物料的加入,两相速度在此附近有较大的振荡。在接近鼓泡床床层表面,固相的速度达到了最大。随S/B的增加CO、H_2的摩尔分数增加,CO_2、CH4的摩尔分数减少,在S/B=3.4时,各气体的摩尔分数趋于稳定。
The kinetic three-dimensional mathematical model of biomass bubbling fluidized bed gasification process was established. The k-ε turbulence model was adopted for the gas phase, the closed model based on the particle kinetic theory was adopted for the solid phase, and the chemical reaction sub-model was self-compiled. The volume fraction of solid phase in the gasifier, the velocity of each phase and the distribution of the components of the gasification products were investigated. The effect of gas-to-biomass mass ratio (S / B) on gasification was also predicted. In the lower part of the bubbling bed, both the solid phase and the vapor phase show oscillatory changes in velocity, especially at bed height H = 0.18 m. Due to the addition of materials, the two-phase velocity has a large oscillation in this vicinity. Near the surface of the bed, the velocity of the solid phase reached its maximum. With the increase of S / B, the molar fraction of H 2 increased and the molar fraction of CO 2 and CH 4 decreased. At S / B = 3.4, the molar fractions of each gas tended to be stable.