Recycling hydrogen purification processing method for producing polysilicon by reducing trichlorosilane

Abstract

The invention discloses a recycling hydrogen purification processing method for producing polysilicon by reducing trichlorosilane. Two groups of metal palladium composite membrane hydrogen purifiers which are serially connected are adopted for carrying out purification processing on recycling hydrogen obtained by trichlorosilane reduction, wherein the first group of metal palladium composite membrane hydrogen purifiers are relatively larger, the ultra-pure hydrogen (H2 purity is more than 99.9999%) after purification processing is returned to a reducing furnace and used as a raw material gas for trichlorosilane reduction; and the second group of hydrogen purifiers are relatively smaller, and the high-pure hydrogen (H2 purity is 99.999%) after purification processing is transmitted to a hydrogen cooling chemical section and used as a raw material gas. The recovery ratio of the recycling hydrogen after the purification processing by adopting the method disclosed by the invention can reach 99%. When hydrogen chloride content is higher in the recycling hydrogen, a necessary dechlorination measure is adopted for lowering HCl content below 0.5 ppm. By adopting the hydrogen purified by the method disclosed by the invention to produce the polysilicon, purity and quality of the polysilicon products can be obviously improved, and an obvious energy-saving emission reduction effect is achieved.

Description

Technical field [0001] The present invention is a method for purifying and treating cyclic hydrogen for polysilicon reduction produced by trichlorosilane. Two sets of metal palladium composite membrane hydrogen purifiers in series are used to purify hydrogen in the trichlorosilane reduction cycle. The first group of metal palladium composite membrane hydrogen purifiers is relatively large, and the purified ultra-pure hydrogen (H 2 Purity>99.9999%) is returned to the reduction furnace to be used for the raw gas for the reduction of trichlorosilane. The second set of purifiers is relatively small, and the purified high-purity hydrogen (H 2 Purity -99.999%) De-cooling hydrogen chemical section is used as raw gas. The recovery rate of the method for purifying and treating the trichlorosilane reduction cycle hydrogen can reach more than 99%. The use of hydrogen purified by the method to produce polysilicon can significantly improve the purity and quality of polysilicon products, a...

AI Technical Summary

Problems solved by technology

[0013] The metal palladium composite membrane hydrogen purifier is used to purify the circulating hydrogen, which can remove these trace CH 4 , O 2 、H 2 O and N 2 And ultra-trace impurities such as B, P, Fe, Ni and Cr are effectively intercepted and removed. However, if only one set of hydrogen purifiers is used, as the hydrogen recovery rate increases, the purity of the purified hydrogen will decrease. Generally, when the hydrogen recovery rate is greater than 92%, recovery of H 2 The purity will be less than 99.9999%

Taking a 3,000-ton / year polysilicon plant as an example, its circulating hydrogen volume is about 25,000m 3 / h, if 8% H 2 empty, then H 2 The discharge volume is 2000m 3 / h, not only causing a serious waste of hydrogen, but also polluting the environment

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