Method for drying hydrogen chloride gas

Abstract

The invention relates to a method for drying a hydrogen chloride gas, which comprises: allowing the hydrogen chloride gas containing water to rise from the bottom part of a drying spray tower along the inner cavity of the drying spray tower; spraying silicon tetrachloride in the inner cavity of the drying spray tower; performing the spray treatment of the hydrogen chloride gas; allowing the sprayed hydrogen chloride gas and the silicon tetrachloride mixed with the hydrogen chloride gas to enter a condenser from the top part of the drying spray tower to perform condensation treatment; and discharging the dried hydrogen chloride gas from the condenser. The silicon tetrachloride decomposes upon the contact with water to form the hydrogen chloride gas and silicon dioxide. The drying of the HCl by using the silicon tetrachloride has the advantages that: the generated HCl can be reused; the water content of the hydrogen chloride gas is reduced to below 50ppm; the conversion rate of silicon powder is improved; the production cost is reduced; the maximum temperature requirement by equipment for operation is 0 DEG C; the cold energy consumption is low; the equipment investment is small; the energy consumption is reduced; and the environmental pollution is relieved.

Description

technical field [0001] The invention relates to a production raw material in the production of trichlorosilane, in particular to a method for drying hydrogen chloride gas in the production of trichlorosilane, and belongs to the technical field of chemical industry. Background technique [0002] Trichlorosilane is a colorless liquid, volatile and deliquescent. The main raw materials for the production of trichlorosilane are industrial silicon and HCl, which are produced in a fluidized bed reactor using silicon powder and hydrogen chloride gas, and decompose and react with water to produce hydrogen chloride gas. It is a first-class flammable material when wet, flammable and explosive, it reacts strongly with oxidants, and burns or explodes when exposed to open flames or high heat. The best external condition for the production of trichlorosilane is to rely on the chlor-alkali plant, which has both direct delivery of chlorine and cheap hydrogen, but the synthesized HCL gas con...

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Problems solved by technology

[0002] Trichlorosilane is a colorless liquid, volatile and deliquescent

The best external condition for the production of trichlorosilane is to rely on the chlor-alkali plant, which has both direct delivery of chlorine and cheap hydrogen, but the synthesized HCL gas contains a lot of water, once the water enters the system, it will be with the Trichlorosilane reacts to form silicon dioxide, which blocks the equipment in the next production process, and ultimately reduces the conversion rate of silicon powder and increases production costs. Therefore, controlling the water content in the raw material hydrogen chloride is the key to increasing the conversion rate and reducing production costs. The essential

[0003] Silicon tetrachloride is a by-product in the production process of trichlorosilane. At present, the scope of use is very narrow, and it is difficult to handle. It has the property of decomposing when it encounters water. It reacts with water to form hydrogen chloride and silicon dioxide. There are no other impurities.

[0004] The traditional process is to reduce the moisture content of hydrogen chloride gas by freezing and cooling. The process is to cool the HCL gas to -17°C with -35°C frozen brine, which can cool most of the water in the HCL gas, thereby To achieve the purpose of drying HCL gas, but this process needs to consume a lot of energy, and the equipment used needs to be made of graphite, which requires a large investment. The water content of hydrogen chloride gas after treatment is about 1000ppm, and the water content is still high, which cannot fundamentally Solve the problem

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