Method for recovering reduction system tail gas in polycrystalline silicon production

Abstract

The invention relates to a method for recovering reduction system tail gas in polycrystalline silicon production. The method comprises the following steps: reduction system tail gas is directly fed into a cold hydrogenation system, hydrogen is injected into the cold hydrogenation system, and the volume of injected hydrogen is 15%-21% of the total gas volume of the cold hydrogenation system; the reduction system tail gas and hydrogen are heated by the cold hydrogenation system at the temperature of 540-560 DEG C; the heated reduction system tail gas and hydrogen are input into a cold hydrogenation reactor for hydrogenation, silicon tetrachloride in the reduction system tail gas is enabled to have a reaction with hydrogen and is directly converted into trichlorosilane, and dichlorosilane in the reduction system tail gas is converted into trichlorosilane through a purifying device in the cold hydrogenation reactor. According to the method, the tail gas exhausted from a reduction furnace is directly subjected to hydrogenation as a raw material without cooling, separation or desorption, so that the process can be shortened, and the purposes of energy saving and consumption reduction can be achieved.

Description

technical field [0001] The invention belongs to the technical field of polysilicon production, and relates to a tail gas recovery method of a reduction system in polysilicon production. Background technique [0002] At present, in the polysilicon production process, reduction furnaces are generally used for reduction. However, in the production of polysilicon, since there are a large number of unreacted and reacted silicon tetrachloride and other components in the reduction furnace, the tail gas must be recovered and reused. [0003] Now, the dry tail gas recovery method is generally used. This dry tail gas recovery method requires cooling, adsorption and other technologies to separate the components such as silicon tetrachloride, hydrogen, trichlorosilane, and dichlorodihydrosilane in the tail gas, and then transport them to different The place is recycled and reused, or the silicon tetrachloride is subjected to cold hydrogenation reaction or thermal hydrogenation reactio...

AI Technical Summary

Problems solved by technology

In the whole recycling process, heat energy and cold energy are used to separate the various components, which consume a lot of electric energy, and special treatment processes and equipment are needed to do it, which increases energy consumption for polysilicon production , and increase the follow-up cost of the enterprise

Furthermore, the separated components sometimes cannot be directly used for reduction production

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