Exhaust recycling technology in production process of polycrystalline silicon

Abstract

The invention discloses an exhaust recycling technology in the production process of polycrystalline silicon. The exhaust recycling technology comprises the following steps that under the catalytic action of a first catalyst, exhaust is subjected to a reaction generated by hydrogen chloride and dichlorosilane in the exhaust, and a first mixture is obtained; the first mixture is cooled to minus 5-55 DEG C, and a first liquid mixture and a first gas mixture are obtained; under the catalytic action of a second catalyst, the first gas mixture is subjected to a reaction generated by dichlorosilane and silicon tetrachloride in the exhaust, and a second mixture is obtained; the second mixture is cooled to be minus 40-minus 10 DEG C, and a second liquid mixture and a second gas-liquid mixture are obtained; the second gas-liquid mixture is subjected to gas-liquid separation, and a third gas mixture and a third liquid mixture are obtained, wherein the main component of the third gas mixture is hydrogen. The phenomena that in the recycling technology in the prior art, hydrogen chloride in the exhaust is absorbed and resolved, and dichlorosilane in the exhaust enters subsequent chlorosilane rectification purification are avoided.

Description

technical field [0001] The invention belongs to the technical field of polysilicon production, and in particular relates to a tail gas recovery process in the polysilicon production process. Background technique [0002] The main components of the tail gas of the reduction furnace or hydrogenation furnace used in the polysilicon production process include: hydrogen, hydrogen chloride, trichlorosilane, dichlorodihydrogen silicon, and silicon tetrachloride. This part of the tail gas must be fully recycled. [0003] The polysilicon tail gas recovery process currently used is mainly: the tail gas of the reduction furnace or hydrogenation furnace used in the production process of polysilicon is passed through the tail gas water cooler, the gas-gas heat exchanger of the tail gas, the frozen brine heat exchanger of -20 ℃ and the tail gas. The subcooler lowers the temperature step by step, using the different boiling points of the components in the tail gas to remove about 30% of th...

AI Technical Summary

Problems solved by technology

Among them, in the above-mentioned tail gas treatment process, the hydrogen chloride in the tail gas is absorbed and analyzed through the absorption tower and the desorption tower, which is not only complicated in equipment and process, but also high in energy consumption.