Method for reclaiming hydrogen from tail gas from polysilicon production

Abstract

The invention relates to a hydrogen recovery method in the exhaust generated by producing polysilicon. The exhaust mainly comprises hydrogen, chlorine hydride, dichlorosilane, trichlorosilane and tetrachlorosilane. The method comprises the following steps: pressurizing and cooling the exhaust in order to turn trichlorosilane and tetrachlorosilane to liquid state while hydrogen, chlorine hydride and dichlorosilane still being gas state, so that the gas hydrogen, chlorine hydride and dichlorosilane can be separated from the liquid trichlorosilane and tetrachlorosilane by gas liquid separation; dissolving the gas chlorine hydride and dichlorosilane into the liquid tetrachlorosilane by passing gas hydrogen, chlorine hydride and dichlorosilane through the liquid tetrachlorosilane, so that separating the hydrogen from chlorine hydride and dichlorosilane. The invention recovers the hydrogen in the exhaust by dry treatment and the hydrogen can be reused in the polysilicon production, which makes good use of the material, reduces pollutants, settles the problem of environmental pollution, improves the product quality and reduces the cost.

Description

Technical field [0001] The invention relates to a method for recovering and processing tail gas produced in the industrial production of polysilicon, and more specifically, to a method for recovering hydrogen from the tail gas produced in the production of polysilicon. Background technique [0002] Polycrystalline silicon is the raw material for the preparation of 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 highest purity requirements in the information industry. It is also a product and industry that the state encourages the development of. [0003] The world’s advanced polysilicon production technology has always been monopolized by companies in the United States, Japan, and Germany. Each company has its own technical secrets and technical characteristics. After continuous research and development, its own production technology has been fo...

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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