Method and system for purifying trichlorosilane from chlorosilane

Abstract

The invention discloses a method and system for purifying trichlorosilane from chlorosilane. The method comprises the following steps: (1) performing the first purification treatment on chlorosilane to obtain trichlorosilane, the first condensed liquid, the first condensed gas and the first liquid-state heavy component; (2) performing the second purification treatment on the first liquid-state heavy component to obtain the second condensed liquid, the second condensed gas and the second liquid-state heavy component; (3) performing condensation treatment on at least one of the first condensed gas and the second condensed gas to obtain the third condensed liquid and the third condensed gas; and (4) performing the third rectification treatment on at least one of the first condensed liquid and the third condensed liquid to obtain the fourth condensed liquid, the fourth condensed gas and the third liquid-state heavy component. The method for purifying trichlorosilane from chlorosilane disclosed by the embodiment of the invention can be used for preparing trichlorosilane required by electronic-grade polycrystalline silicon.

Description

technical field [0001] The invention belongs to the field of polysilicon production, in particular, the invention relates to a method and a system for purifying trichlorosilane from chlorosilane. Background technique [0002] The application number is 201010576949.8, and the invention patent titled "a rectification process for trichlorosilane" discloses a rectification process for purifying trichlorosilane. The material is fed into the middle of the distillation tower, and the output from the top of the tower enters the middle of the secondary rectification tower, and the material from the bottom of the tower is sent to the storage tank as a finished product of silicon tetrachloride; the output from the top of the secondary distillation tower enters the light component storage tank, The extracted material from the tower kettle enters the middle part of the third-stage rectification tower; the extracted material from the top of the third-stage rectification tower enters the l...

AI Technical Summary

Problems solved by technology

The above scheme has the following disadvantages: (1) the light components and heavy components produced by the rectification system are not recycled, resulting in a large waste of materials; (2) the tail gas produced by the rectification tower is not recycled, and the Under the operating conditions in the patent, the emission of exhaust gas is relatively large, and more chlorosilanes are entrained in the exhaust gas, resulting in waste of materials

The above scheme has the following disadvantages: (1) Each rectification tower is equipped with two-stage tail gas coolers, the cooling medium of the primary cooler is 5-7°C chilled water, and the cooling medium of the secondary cooler is -25--30°C Frozen brine, these two cooling media require two sets of different refrigeration units for refrigeration, and the initial equipment investment and operation consume a lot of energy; (2) There are a large number of coolers, and the temperature of the refrigerant is lower than that of the outdoor for most of the year (3) the dichlorodihydrosilane produced in the rectification process has not been further recycled, resulting in a large material loss; (4) the final silicon tetrachloride product contains more heavy components, which cannot be directly used in downstream processes

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