Method and device for removing impurities from trichlorosilane mixed gas

Abstract

The invention discloses a method and a device for removing impurities from a trichlorosilane mixed gas. The method comprises the steps of: carrying out primary spraying on the trichlorosilane mixed gas in a gas and steam mixture humidifying tower by adopting silicon tetrachloride liquid, absorbing metal chloride and siliceous dust by silicon tetrachloride, introducing wet hydrogen in the trichlorosilane mixed gas to obtain SiO2 through reaction, absorbing boron and phosphorus in the trichlorosilane mixed gas through the SiO2; carrying out secondary spraying on the trichlorosilane mixed gas with the silicon tetrachloride liquid in a bubble column, and further removing the metal chloride to obtain a finished product of a trichlorosilane synthesis gas; and connecting the bubble column used for collecting the silicon tetrachloride obtained by spraying the silicon tetrachloride mixed gas for two times to a washing liquid distilling tower, distilling and purifying the silicon tetrachloride with impurities, and circularly spraying by using the silicon tetrachloride. The impurities are removed by adopting a wet method, the impurities in the trichlorosilane mixed gas can be fully removed to obtain high-quality refined trichlorosilane, the silicon tetrachloride can be circularly utilized, and the purposes of saving energy, reducing consumption and decreasing emission are achieved.

Description

technical field [0001] The invention relates to a synthesis process of trichlorosilane, in particular to a treatment method and device for removing impurities from trichlorosilane mixed gas. Background technique [0002] During the polysilicon production process, the trichlorosilane synthesis gas (mainly composed of trichlorosilane, silicon tetrachloride, dichlorodihydrosilane, hydrogen, hydrogen chloride and other gases) generated from the trichlorosilane synthesis furnace contains various Impurities (including boron B, phosphorus P, and various metal chlorides), among which the removal of B and P impurities is a common headache in the polysilicon industry. At present, most of them adopt single-effect distillation and purification methods, and the cooling capacity at the top of the tower and the heat at the bottom of the tower are not sufficient. Comprehensive utilization, high energy consumption. Contents of the invention [0003] The object of the present invention is ...

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Problems solved by technology

[0002] During the polysilicon production process, the trichlorosilane synthesis gas (mainly composed of trichlorosilane, silicon tetrachloride, dichlorodihydrosilane, hydrogen, hydrogen chloride and other gases) generated from the trichlorosilane synthesis furnace contains various Impurities (including boron B, phosphorus P, and various metal chlorides), among which the removal of B and P impurities is a common headache in the polysilicon industry. At present, most of them use single-effect distillation to purify, and the cooling capacity at the top of the tower and the heat at the bottom of the tower are not sufficient. Comprehensive utilization, high energy consumption

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