Recovery system and recovery method of by-product in polycrystalline silicon production

Abstract

The invention discloses a recovery system and a recovery method of a by-product in polycrystalline silicon production. The system and the method are used for recycling the hydrogen, chlorosilane and chlorine hydride gas in the reducing tail gas produced during the polycrystalline silicon production. The recovery method comprises the following steps: a condensing step for separating most of chlorosilane from the reducing tail gas; an adsorption step for removing all chlorine hydride and the rest chlorosilane from the reducing tail gas by using an absorption unit after the condensing step to obtain the pure hydrogen; a regenerating step for regenerating the absorption unit by using the hydrogen so as to remove the chlorosilane and chlorine hydride absorbed by the absorption unit, and obtaining the regenerative gas containing hydrogen, chlorosilane and chlorine hydride; and a cold hydrogenating step for directly feeding the regenerative gas as the raw material of the cold hydrogenation reaction to a cold hydrogenation reactor. According to the system and method provided by the invention, the HCl can be singly separated from the tail gas without an adsorption-de-adsorption device so as to prevent the HCl from being condensedly separated and gasified, and a great number of heat and cooling capacity is saved.

Description

technical field [0001] The invention relates to the field of polysilicon production, in particular to a recovery system and recovery method for by-products in polysilicon production. Background technique [0002] At present, more than 80% polysilicon enterprises at home and abroad adopt the improved Siemens method, but due to the low conversion rate of silicon tetrachloride and high energy consumption in the thermal hydrogenation process, some polysilicon manufacturing enterprises have replaced it with cold hydrogenation process Traditional thermal hydrogenation is used to realize the closed cycle of chlorosilane in the production system, and achieve the purpose of saving energy and reducing consumption. [0003] Recovery systems for the by-products of polycrystalline production are widely used, such as figure 1 shown. The by-product reduction tail gas including hydrogen, chlorosilane and hydrogen chloride produced during polysilicon production is sent to the first condens...

AI Technical Summary

Problems solved by technology

[0004] Cold hydrogenation was originally a process used to prepare trichlorosilane in the early stage of the silane method, and it was directly introduced into the improved Siemens method. Although compared with the traditional improved Siemens method, its energy consumption can be greatly reduced, but due to two different systems Integration between, so there is still room for further optimization

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