单喷嘴水煤浆气化炉高径比对反应流动的影响

Influences of height-diameter ratio on multiphase reaction flow of single-burner coal water slurry gasifier

建立了综合数学模型对某化工厂单喷嘴水煤浆气化炉内多相湍流反应流动过程进行数值模拟,分析了气化炉直段高径比对气化炉内反应流动的影响。由结果可知:现有气化炉高径比较短,炉内存在射流区和回流区,回流区一直延伸到气化炉底部;当直段高径比大于2.3时,出现平推流区;除射流火焰区外,从上到下炉内温度及CO_2和H_2O体积分数先升高后降低,而CO和H_2体积分数先降低后升高。直段高径比增大,平推流区体积分率增大,出气化炉有效气含量、碳转化率和有效气产率都增大,单位有效气氧耗减小;当直段高径比大于4.3时,以上气化炉性能数据趋于稳定值。高径比增大,有利于提高飞灰颗粒停留时间和壁面熔渣反应时间,提高气化炉效率。

A comprehensive numerical model was developed for simulation of the multiphase reaction flow process in a single-burner gasifier,and the influences of the gasifier height-diameter ratio（ H/D） on multiphase reaction flow were investigated. The results show that the flow field of the single-burner gasifier is composed of jet region and reflux region,and the end of the reflux region is located at the bottom of the gasifier. The plug-flow region occurs when H/D is higher than 2. 3. Except the jet flame region,the gas temperature and the volume fraction of CO_2 and H_2O increase fist and then decrease along the height of gasifier,however,the volume fraction of CO and H_2 decreases first and then increases. The volume fraction of the plug flow region,the volume fraction of the effective gas,carbon conversion ratio and effective gas yield increase with the increasing H/D,but the oxygen consumption of per cube meter effective gas decreases. When the H/D is higher than 4. 3,all the above gasfier performance parameters tend to stable. The increasing of the H/D is beneficial to increase the fly ash particle residence time and the reaction time of slag particle adhered in the gasifier wall,thus the efficiency of gasifier performance is enhanced.