多晶硅还原尾气回收工艺的优化

Optimization of polysilicon reduction off-gas recovery technology

阐述了多晶硅还原尾气回收的主要工艺过程,并用Aspen大型过程模拟软件进行了模拟优化,在分析讨论干法回收工艺存在的主要问题的基础上,对现有工艺进行了优化改进。将作为吸收剂的氯硅烷在吸收塔的进料温度从-40℃降至-50℃,HCL解析塔塔顶气液相混合出料改为气相出料,同时增加解析塔换热器,减少了作为吸收剂的氯硅烷循环量,热量利用更加合理,能耗显著下降,大大降低了回收成本,同时回收氢气中杂质质量分数从11.14%减少至5.99%,降低了吸附塔操作负荷,提高了回收氢气品质,有利于多晶硅产品质量的稳定;同时将HCL的回收率从96.61%提高到99.98%,降低了氯耗;与此同时,大幅度降低了冷、热负荷的消耗且采用低品位蒸汽取代高品位蒸汽,节能降耗效果十分明显。

The main technologies of polysilicon reduction off-gas recovery were briefly reviewed,and the technology was optimized with Aspen,large-scale process simulation software,based on the analysis of the main problems existing in the dry recovery technology.The temperature of chlorosilane absorbent was reduced from-40℃to-50℃,and the mixed vapor-liquid distillate of distillation tower was replaced by vapor discharge.Meanwhile,heat interchanger of distillation tower was added to significantly reduce the circulation rate of absorbent,energy consumption and the cost of recycling as well.Impurities in the recovered hydrogen were reduced from 11.14% to 5.99%.With lower operation load of adsorption column,and higher hydrogen recovery quality,the feedstock quality was maintained stably in favor of the stability of the polysilicon product quality.The recoveries of hydrogen chloride increased from 96.61% to 99.98%,which reduced chlorine consumption and meanwhile greatly lowered the consumption of colling and heating load.Besides,instead of high grade steam,energy saving and consumption can be effectively obvious when using low grade steam.