Decompression acid making process of polysilicon 10barg HCl (hydrogen chloride) tail gas

Abstract

The invention relates to a decompression acid making process of polysilicon 10barg HCl (hydrogen chloride) tail gas, in particular to a specific process technology by which gasification, decompression and water absorption are carried out on 10barg liquid chlorine hydride separated and extracted from the production of polysilicon, thus the tail gas becomes hydrochloric acid and is further recycled. The production process is as follows: heating the liquid chlorine hydride with the pressure of 10barg and the purity of 99%, which is separated and purified by a polysilicon production tail gas recovery unit, to 10-20 DEG C through a heating gasifier, leading the liquid HCl to change from the liquid state to the gas state; then decompressing gas HCl with the pressure of 10barg to 0.1-0.5barg through a decompression device; further introducing the HCl into a spray absorption device for carrying out the water absorption; carrying out circulating counter-current multi-stage concentration and absorption; and producing and preparing the hydrochloric acid with the concentration of 26-31%. In the production process of the polysilicon, as the hydrochloric acid is prepared by exhausting the 10barg HCl separated and purified by the tail gas recovery unit to an HCl thickening absorption device of a waste gas and waste liquid treatment system when a fault occurs in the TCS (trichlorosilane) synthesis, a reasonable treatment way is found out for the 10barg HCl during an accident, thereby ensuring the normal production of a reduction unit, a transformation unit and the tail gas recovery unit, and enhancing the anti-accident capacity of a polysilicon production line.

Description

1. Technical field [0001] The invention relates to a process for producing polysilicon 10 barg HCl tail gas under reduced pressure to produce acid. It is a specific process technology for separating and purifying 10 barg of liquid hydrogen chloride from polysilicon production through gasification, decompression and water absorption to turn it into hydrochloric acid and recycle it. 2. Background technology [0002] HCl is gaseous at normal temperature and pressure, and liquid at cryogenic temperature and high pressure. It is extremely volatile and difficult to store. Once the temperature rises, the liquid HCl will volatilize into gas, and the pressure will rise sharply, causing overpressure in the container and even causing an explosion, which poses a great safety hazard. [0003] In the process of polysilicon production, CDI technology is used to separate and purify the reduced and converted tail gas, and produce 10 barg HCl with a purity of 99%. Under normal circumstances,...

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Problems solved by technology

[0005] The purpose of the present invention is to provide a kind of polysilicon 10bargHCl tail gas decompression acid production process, it can overcome and change in the existing polysilicon production technology, because TCS synthesis breaks down, 10bargHCl is difficult for storage, difficult to handle, easy to explode, affects polysilicon production disadvantages, but also provides a new method for the recycling of its by-products

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