Method for recovering tail-gas generated during producing polycrystalline silicon using silicon tetrachloride

Abstract

A method for recovering tail gas produced in the process of polysilicon production by tetrachlorosilane comprises the following steps: the tail gas is leached by liquid tetrachlorosilane; the leached tail gas is pressurized and cooled; and hydrogen is separated from hydrogen chloride and dichlordihydrosilicate by an absorbent; the separated hydrogen is absorbed and filtrated by an absorbent, the hydrogen can be recovered; the hydrogen chloride and chlorosilane in the absorbent are heated, the gaseous hydrogen chloride and the gaseous chlorosilane are taken out by the hydrogen, and then the tail gas is recycled; the liquid tetrachlorosilane is heated and / or pressurized, therefore, the hydrogen chloride and the dichlordihydrosilicate are desorbed; and the hydrogen chloride and / or the dichlordihydrosilicate are recovered by gas-liquid separation. By adopting a dry method, the tail gas treated by the method can be reused in the polysilicon production, therefore, the method has the advantages of adequate utilization of raw materials, reducing pollutants, solving the problem of environmental pollution, improving product quality and lowering cost.

Description

technical field [0001] The invention relates to a method for recovering and treating tail gas produced by industrial production of polysilicon, more specifically, to a method for recovering tail gas produced by producing polysilicon by using silicon tetrachloride. Background technique [0002] Polycrystalline silicon is the raw material for preparing monocrystalline silicon, which is ultimately used in the production of integrated circuits and electronic devices. It is one of the basic raw materials with the largest consumption and the highest purity requirements in the information industry. It is also a product and industry that the country encourages the development of. [0003] The world's advanced polysilicon production technology has always been monopolized by companies from the United States, Japan, and Germany. Each company has its own technical secrets and technical characteristics. After continuous research and development, it has formed its own production process. ...

AI Technical Summary

Problems solved by technology

[0004] my country's polysilicon industry started in the 1950s, realized industrialization in the mid-1960s, and developed blindly in the early 1970s. There were more than 20 production plants, all using traditional Siemens technology, backward technology, serious environmental pollution, and material consumption. Large, high production costs, most enterprises lose money and stop production or change production one after another

[0005] The outstanding feature of the traditional polysilicon production process is the tail gas wet recovery technology, that is, the tail gas in the reduction furnace is initially pressurized to separate chlorosilane and then washed with water to recover hydrogen. Due to the process of water washing, impurity gases such as oxygen and carbon dioxide in the water will be released. Contamination of hydrogen, so a large amount of recovered hydrogen needs to be purified again. During the leaching process, chlorosilane is hydrolyzed to produce sewage, which needs further treatment, resulting in environmental pollution and large material consumption.

At the same time, the hydrogen generated in the production has not been fully utilized, which not only wastes energy, but also causes environmental pollution

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