A polycrystalline silicon reduction tail gas condensation method and system

Abstract

A polycrystalline silicon reduction tail gas condensation method is provided. The method includes performing a first time of cooling treatment on the reduction tail gas by utilizing environment air; performing a second time of cooling treatment on the reduction tail gas subjected to the first time of cooling treatment by utilizing a cooling capacity from an absorption tower bottom; performing a third time of cooling treatment on the reduction tail gas subjected to the second time of cooling treatment by utilizing frozen brine; performing a first time of gas liquid separation on the reduction tail gas subjected to the third time of cooling treatment; cooling noncondensable gas obtained after the first time of gas liquid separation by utilizing a refrigerant; subjecting the noncondensable gas cooled by the refrigerant to a second time of gas liquid separation; mixing liquid-phase chlorosilane obtained by the two times of gas liquid separation; conveying the mixture to a desorption tower; and by utilizing the cooling capacity obtained after the second time of gas liquid separation, cooling the reduction tail gas after the second time of cooling treatment before cooling treatment by utilizing the frozen brine is performed. Correspondingly, a condensation system is provided. Cooling capacity utilization of the condensation method and the condensation system is reasonable.

Description

technical field [0001] The invention relates to the technical field of polysilicon production, in particular to a polysilicon reduction tail gas condensation method and a polysilicon reduction tail gas condensation system. Background technique [0002] Polysilicon is the building block material for the solar photovoltaic industry. At present, the production of polysilicon mainly adopts the improved Siemens method (that is, the reduction method of trichlorosilane), which refers to the use of vapor deposition method in the reduction furnace through H 2 to reduce SiHCl 3 Thereby preparing polysilicon, the specific reaction equation is: [0003] 3SiHCl 3 +H 2 →2Si+5HCl+SiCl 4 [0004] Because the temperature and other conditions in the reduction furnace are difficult to achieve uniformity, the actual reduction process is very complicated, accompanied by side reactions, which makes the components in the reduction tail gas more complicated, mainly including H 2 , HCl gas an...

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Problems solved by technology

[0008] It can be seen that during the implementation of the above-mentioned technical solution, liquid-phase chlorosilanes at temperatures of 15 to 20°C, -10 to -15°C, -20 to -25, and -35 to -45°C are all sent to the chlorosilane buffer. In tank D, chlorosilanes in different temperature ranges are mixed, so that the temperature of chlorosilanes at higher temperatures (such as 15-20°C) is lowered, while the temperature of chlorosilanes at lower temperatures (such as -35-45°C) The temperature of silane rises, resulting in the loss of cooling capacity, and the utilization of cooling capacity is unreasonable

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