Hydrogenation method for quickly circulating fluidized silicon tetrachloride

Abstract

The invention relates to a hydrogenation method quickly for circulating fluidized silicon tetrachloride, and method comprises the following steps of: mixing pre-treated silicon power into a hydrogenation rector from the middle, wherein the pressure is 1-5MPa, and charging mixed gas of hydrogen and silicon tetrachloride with the preheating temperature of 400-600DEG C (the molar ratio is 1:(1-5)) into the hydrogenation rector from the bottom; in the hydrogenation rector, wherein the macroscopic tolerance is 0.2-4m / s; quickly fluidizing the silicon power; and carrying out the gas-solid separation on the product gas and the silicon power flowing out of the top of the reactor by a first-stage cyclone separator or a multi-stage cyclone separator, and reflowing the silicon power into the reactor by a circulating pipe, wherein the product gas passes through a waste heat recovery system, a condensation system and a separation system, the trichlorosilane is taken as a hydrogenated product, and the separated silicon tetrachloride and hydrogen can be recycled. The method has the advantages that the gas and the solid can be sufficiently contacted with each other, the heat and the mass can be quickly transferred, and the silicon tetrachloride is high in conversion per pass; a bed layer is even in temperature field, and the product is stable in quality; and the hydrogenation rector of a circulating fluidized bed is high in operation elasticity, high in capacity, and easy for realization of the large-scale production.

Description

technical field [0001] The invention relates to a hydrogenation method of silicon tetrachloride, in particular to a rapid circulation fluidized hydrogenation method of silicon tetrachloride. technical background [0002] During the polysilicon production process, about 14 tons of silicon tetrachloride by-products will be produced for every ton of polysilicon produced. If silicon tetrachloride cannot be recycled or handled improperly, it will not only cause waste of resources, increase the production cost of polysilicon, but also cause major environmental disasters. [0003] Hydrogenation of silicon tetrachloride can obtain high-purity trichlorosilane, which is the raw material for polysilicon production. Therefore, the hydrogenation of silicon tetrachloride solves the recycling of silicon tetrachloride and realizes the closed-circuit production of polysilicon production process. [0004] According to the difference of feed and reaction temperature, the hydrogenation method...

AI Technical Summary

Problems solved by technology

The disadvantages of thermal hydrogenation of silicon tetrachloride are high reaction temperature, high energy consumption, low single-pass conversion rate of silicon tetrachloride, complex process flow, and difficult device operation, etc.

The problem is that the gas-solid contact condition needs to be improved; the macroscopic gas velocity is small, and the silicon tetrachloride treatment capacity is limited; the single-pass conversion rate of silicon tetrachloride is still quite different from the theoretical conversion rate, and there is still a great improvement space

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