Method for preparing high purity polysilicon particle with fluidized bed and bed fluidizing reactor

Abstract

The invention provides a method for preparing high-purity polysilicon particles with a fluidized bed and a fluidized bed reactor, the heating zone and the reaction zone of the fluidized bed are separated from each other in structure. The method for preparing high-purity polysilicon particles by a fluidized bed comprises the steps as follows: a) a fluidizing gas without silicon is inlet to the heating zone of the reactor to lead the polysilicon particles in the heating zone to be a fluidized state, the polysilicon particles are heated by a heating device; b): the heated polysilicon particles are delivered to the reaction zone to which the gas with silicon is inlet, the gas with silicon carries out thermal decomposition or reduction at the surface of the polysilicon particles, thus simple substance silicon is produced and settled on the surface of particles; c): part of polysilicon particles with 0.1-10mm particle size are taken from the lower part of the reactor as the products; d): thefine polysilicon particles which have the diameter of 0.01-1.0mm and are taken as the seed crystal are added to the upper part of the reactor to maintain the quantity of the polysilicon particles inthe reactor. The method and the fluidized bed reactor of the invention have the advantages that the wall of the reactor has less silicon deposition; the reactor can operate continuously for a long period with low energy consumption, etc.

Description

technical field [0001] The invention relates to a method suitable for preparing high-purity polysilicon particles and a fluidized bed reactor, belonging to the field of chemical technology and equipment. Background technique [0002] Polycrystalline silicon is the raw material for preparing monocrystalline silicon and solar cells, and is the foundation of the global electronics industry and photovoltaic industry. According to the purity of silicon content, it can be divided into solar grade silicon (6N) and electronic grade silicon (11N). In the past, silicon materials for solar cells mainly came from off-grade electronic-grade silicon, monocrystalline silicon head and tail materials, pot bottom materials, etc., and the annual supply was very small. With the rapid development of the photovoltaic industry, the demand for polysilicon in solar cells is increasing rapidly. Therefore, countries all over the world are competing to develop new preparation technologies and process...

AI Technical Summary

Problems solved by technology

[0010] Although the technical solutions disclosed in US5,382,412 and US6,007,869 provide a heating zone and a reaction zone, they do not effectively separate the heating zone and the reactor. Due to the strong back-mixing characteristics of the fluidized bed, the reaction zone Part of the silicon-containing reaction gas is mixed back into the heating zone, resulting in deposition on the wall of the heating zone

In addition, there is a strong heat exchange between the particles and the inner wall of the reactor in the heating zone, so that the temperature of the inner wall of the reaction zone is close to the temperature of the silicon particles, which will also lead to the deposition of silicon-containing reactors on the inner wall of the reaction zone

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