System and method for producing trichlorosilane by cold hydrogenation of silicon tetrachloride

Abstract

The invention discloses a system and a method for producing trichlorosilane by cold hydrogenation of silicon tetrachloride. The system comprises a hydrogenation reaction device, wherein the hydrogenation reaction device is used for carrying out a cold hydrogenation reaction on raw materials including silicon tetrachloride, hydrogen and silicon powder to generate needed trichlorosilane; and the hydrogenation reaction device comprises multi-stage hydrogenation reactors connected in series. When the hydrogenation reaction device works, silicon tetrachloride sequentially passes through each stage of hydrogenation reactor, in which a cold hydrogenation reaction is carried out respectively. At least two hydrogenation reactors are connected in series, so that a one-time hydrogenation rate is far more than that of the conventional cold hydrogenation process added with a catalyst, thus various of consumption, such as heat energy, electric energy and the like for production of trichlorosilane are indirectly reduced. As no catalyst is used in the method, a lot of costs required by purchasing of the catalyst are saved; compared with wearing on pipelines and equipment caused by addition of the catalyst in the prior art, the cold hydrogenation system can be operated stably for a long period of time, and a produced trichlorosilane product has better quality.

Description

technical field [0001] The invention relates to the field of polysilicon production, in particular to a system and a method for producing trichlorosilane by cold hydrogenation of silicon tetrachloride. Background technique [0002] Polysilicon production is an energy-intensive industry. How to improve the process and reduce production costs has become the focus of sustainable development of various enterprises. As a large energy-consuming cold hydrogenation process after the polycrystalline reduction process in polycrystalline production, its internal energy recycling and the improvement of primary hydrogenation rate occupy a large proportion in the energy saving and consumption reduction of the whole system. [0003] At present, the general system structure diagram of the cold hydrogenation process in polysilicon enterprises is as follows: figure 1 shown. The silicon tetrachloride liquid and the preheated hydrogen enter the silicon tetrachloride vaporizer to mix, and the ...

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Problems solved by technology

[0004] In the existing cold hydrogenation process, there are at least the following defects: 1) the heat contained in the reaction product gas is consumed by the condensation unit, resulting in a large amount of waste of refrigerant and heat medium; 2) a large amount of catalyst needs to be consumed; 3 ) The catalyst contains impurities such as aluminum and iron, which not only cause serious wear to the inner wall of the hydrogenation reactor, pipes, and valves, but also reduce the quality of trichlorosilane products; 4) The primary hydrogenation rate is low, only about 25%

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