Environmental Protection Process For Improved Siemens Method Of Polysilicon Production

Polycrystalline silicon is an essential part of solar energy photovoltaic industry foundation engineering materials.In recent years,solar photovoltaic industry is developing rapidly.Although recently the photovoltaic industry in our country has been repressed by foreign,downstream demand and market prices is slowdown.A few years ago,there was another for polysilicon pollution caused by environmental problems,cause high attention at home and abroad,and industry has caused quite a blow.But in the long run,photovoltaic industry is still broad prospects.In the polysilicon production process,the improved Siemens process is the most widely used at present.This process solves the problem basically such as the energy and materials in the traditional process can not be recycled,the serious environmental pollution,product quality is not stable,and more.But still cannot achieve closed-circuit circulation.This article,combined with practical production experience,analysis the method of improved Siemens polysilicon production technology through to the domestic three-production capacity of polysilicon enterprises investigation.From the view of the process design,pollution control,cleaner production production process material in of the green development,test and research material recycling schemes on the production process,the comprehensive utilization of by-products silicon tetrachloride method and chloride ions for polysilicon wastewater removal solution,determine the influencing factors and optimum process conditions of running and optimization scheme,etc.These methods will provide effective environmental advice and guidance for the polysilicon enterprises under construction,proposed or implementing technology to upgrade,and also provide reference and reference for the oversight of the department of environmental protection in the future,and to be environmentfriendly enterprises.Exhaust pressure and cryogenic recovery process can effectively recycle exhaust chlorosilane in the material.We recommend using-35? cryogenic refrigerant in production tail gas recovery.The residual liquid recycling system can effective recovery of residual liquid more than 99% of silicon tetrachloride with the difficult of silicon tetrachloride residual liquid.For large volume,high nitrogen and hydrogen component of smog,neutralization device by exhaust directly on the tail gas absorption process.Through research on comprehensive utilization of a variety of silicon tetrachloride method,this article mainly recommend the silicon tetrachloride hydrogenation,transformation and production of high purity gas phase silica fiber silicon tetrachloride three ways.Calcium chloride evaporation crystallization device can effectively remove chlorine ion in polysilicon production wastewater.This article has also researched the polysilicon chemical risk control problem in recently high-profiled,and put forward the environmental risk control points and Suggestions in polysilicon production through the analysis of the operating experience of the domestic advanced polysilicon production enterprises and the leaking accident of accident lesson.