Optimization Research Of Trichlorosilane Synthesis Process

Trichlorosilane is frequently used in the synthesis organic silane coupling agent,as well as the main raw material of the preparation for polysilicon.As the wider applications,its demand rapidly increases in recent years.But coMPared with advanced foreign technology,the domestic trichlorosilane production still faces many difficult problems,such as instable production,lacking of comprehensive utilization of the by-product and wasting of resources in tail gas recovering.This paper points out the technical problems existing in all the Silicon hydrogen chlorination process for the synthesis of the trichlorosilane which iMPact the stable operation of the whole system by analyzing the process itself,and also puts forward some optimization measures by studying various problems.First,the source of water in the hydrogen chloride as well as the influence of water content on the system was analyzed for the hydrogen chloride synthesis process.Through the experiment coMParison,it is summed up that,the water content in the hydrogen chloride gas must be controlled below 0.1%,and then the conversion rate of trichlorosilane can be increased to 88%.Meanwhile,the influence of the purity of hydrogen chloride on the trichlorosilane synthesis system was analyzed,and by contrast experiment,it is concluded that,the purity of hydrogen chloride should be controlled between 90%and 95%,while excess 5%to 10%of the hydrogen,the system can take away the heat in time to improve the selectivity of the main reaction.At the synthesis furnace outlet,the content of trichlorosilane in mixed gas can be increased to 35%.Second,the influences of the structures of the hydrogen chloride inlet pipe,funnel cap and warm water tube bundle in the trichlorosilane synthetic furnace on the system were studied and the optimization measures were put forward;By changing funnel cap,the content of trichlorosilane in the synthesis gas was up to 35%.The warm water tube bundle is greatly improved,and the damage cycle is extended from the original 20 days to 60 days.The optimal control index of silicon powder impurities is concluded,Al:0.15%~0.3%.The results show that the content of trichlorosilane in the synthesis gas increases from 18%to 35%when the pressure of the synthesis furnace is controlled at 10~20 kPa.Third,for the synthetic gas dedusting and condensation process,the causes of system congestion was studied and the equipment structure and system operation mode were optimized.The continuity of the entire system is improved,the system production cycle is extended from the original 20 days to more than 60 days.Finally,the using of pressure swing adsorption technology to recover the synthetic tail gas was proposed for the synthetic tail gas recovery process.And the research showed that,through pressure swing adsorption technology,the hydrogen and hydrogen chloride in tail gas can be recovered at the same time.For 600 Nm~3/h of raw gas,322.5 Nm~3/h of hydrogen and 277.5 Nm~3/h of hydrogen chloride can be recovered,which achieves the goal of energy saving and consumption reduction.