鼓泡流化床中生物质气化的数值模拟

Numerical Simulation of Biomass Gasification in a Bubble Fluidized Bed

为更好地进行流化床的设计及优化,建立了鼓泡流化床中生物质气化的数值计算模型.对鼓泡流化床中以空气为气化介质的木材的气化进行了数值计算,并与实验结果进行比较.着重考察了燃料与空气质量比、颗粒粒径、初始床高以及热边界条件对生物质在空气中气化产物的影响.结果表明,数值计算结果与实验结果吻合良好,说明该模型可较好地用于计算鼓泡流化床中生物质的气化;燃料与空气质量比对生物质气化生成的气体产量和气体组成都有显著的影响,其影响最高可达25%;颗粒粒径也有一定的影响,其影响约为10%;增大燃料与空气质量比和减小颗粒粒径都可使气体产量增大,同时有利于燃料气体(CO、H2和CH4)的生成;初始床高和热边界条件的影响都不明显,初始床高的影响小于5%,而热边界条件的影响则小于1%.

For better design and optimization of a fluidized bed,a numerical simulation model for computing biomass gasification in a bubble fluidized bed was presented. Simulation results of wood gasification in a bubble fluidized bed using air as gasifying agent were compared with experimental results. Numerical analysis was carried out focusing on the influence of fuel/air ratio,granule diameter,initial bed height,and thermal boundary conditions on biomass gasification products using air as gasifying agent. The numerical results indicate that the simulation and experimental results agree well,proving that the numerical simulation model is applicable in computing biomass gasification in a bubble fluidized bed. There is a remarkable influence of fuel/air ratio,of up to 25%,on gas amount and its composition,while granule diameter has an effect of about 10%. Gas amount and fuel gas（CO,H2,CH4）production are increased by increasing fuel/air ratio or decreasing granule diameter. The results demonstrate relatively low influence of initial bed height of less than 5% and thermal boundary conditions of only 1%.