下吸式固定床气化炉的气化过程及气化特性模拟分析

Analysis of Gasification Process and Gasification Characteristics of Downdraft Fixed Bed Gasifier

为研究下吸式固定床气化炉内多相反应流场对气化过程的影响,基于Fluent软件,建立欧拉-拉格朗日模型追踪秸秆颗粒运动,P1模型模拟气化过程的辐射传热过程,同时耦合化学反应,对下吸式秸秆气化炉气化特性进行了分析。结果表明:燃料系数0.26,秸秆颗粒粒径13 mm,在距离燃烧器底部出口4.85 m处,秸秆挥发分开始与气化剂发生燃烧反应,气化炉中心位置处的火焰温度升高,随后随着挥发分燃烧耗尽温度逐渐下降。秸秆颗粒粒径从10 mm增加到30 mm时,产生的H 2、CO和CH 4可燃气摩尔分数逐渐降低,但差距不大;颗粒粒径为40 mm时会出现秸秆颗粒未完全燃烧现象,导致可燃气体产量严重下降,气化炉内的温度分布不稳定。

In order to study the effect of the multiphase reaction flow field on the gasification process in downdraft fixed-bed gasifier,based on Fluent software,Euler Langrange model was established to track the movement of straw particles.P1 model was used to simulate the radiation heat transfer process of gasification process.At the same time,the gasification characteristics of straw downdraft gasifier were analyzed by coupling chemical reactions.The results showed that when the fuel coefficient was 0.26 and the particle size of straw was 13 mm,the volatiles of straw begin to react with the gastifier at the distance of 4.85 m from the bottom outlet of the burner.The flame temperature at the center of the gasifier increased,and then decreased with the depletion of volatiles.When the particle size of straw particles increased from 10 mm to 30 mm,the flammable gas content gradually decreased,but the content gap was not large.When the particle size of straw reached 40 mm,the temperature in gasifier dropped rapidly,then the serious phenomenon of incomplete dry volatilization would happen.