Synthetic method and apparatus for trichlorosilane

Abstract

The invention discloses a synthetic method and apparatus for trichlorosilane. According to the method, silicon powder with a particle size in a range of 200 to 400 meshes is used for reaction with hydrogen chloride so as to synthesize trichlorosilane; the used silicon powder has a wide particle size range and is low in production cost and reduced in the difficulty coefficient of production; and since the silicon powder in a wide particle size range has low fluidizing gas velocity, the mole fraction of corresponding introduced hydrogen chloride can be reduced during preparation of trichlorosilane, so difficulty of and cost for tail gas recovery is lowered. Compared with silicon powder used in preparation of trichlorosilane in the prior art, the silicon powder in a particle size range of 200 to 400 meshes in the invention has a greater specific surface area, so a gas-solid contact area is increased and reaction intensity is improved; and thus, the production power of the synthetic method and apparatus for trichlorosilane in the invention is improved.

Description

technical field [0001] The invention belongs to the technical field of polysilicon production, and in particular relates to a method and a device for synthesizing trichlorosilane. Background technique [0002] The production of trichlorosilane by the chlorination method is produced by the gas-solid heterogeneous reaction of metallurgical grade silicon powder and hydrogen chloride gas in a fluidized bed synthesis furnace. Large particle silicon powder in the diameter range, this production process has the following disadvantages: (1) the production cost of industrial silicon powder is high, because the particle size range of silicon powder is narrow, the difficulty of the production process increases, resulting in an increase in production costs; (2) The fluidization gas velocity of large-particle silicon powder is high. In order to ensure the fluidization effect, the flux of hydrogen chloride needs to be increased, resulting in excessive hydrogen chloride in the system, whic...

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Problems solved by technology

[0002] The production of trichlorosilane by the chlorination method is produced by the gas-solid heterogeneous reaction of metallurgical grade silicon powder and hydrogen chloride gas in a fluidized bed synthesis furnace. Large particle silicon powder in the diameter range, this production process has the following disadvantages: (1) the production cost of industrial silicon powder is high, because the particle size range of silicon powder is narrow, the difficulty of the production process increases, resulting in an increase in production costs; (2) The fluidization gas velocity of large-particle silicon powder is high. In order to ensure the fluidization effect, the flux of hydrogen chloride needs to be increased, resulting in excessive hydrogen chloride in the system, which increases the difficulty and cost of tail gas recovery; (3) The specific surface area of ​​large-particle silicon powder Smaller, the gas-solid contact surface is smaller, and the intensity of the reaction is weaker, which limits the increase in the production capacity of the trichlorosilane synthesis unit;

[0003] The main reason why most of the current production processes do not use silicon powder with finer particle size is: (1) fine silicon powder is easily taken out of the fluidized bed by gas in the fluidized bed, and because the traditional process does not recycle, resulting in silicon powder The decline of powder utilization rate leads to the increase of production cost

(2) There are many impurities contained in fine silicon powder, which are easy to cause enrichment at the distribution plate of the synthesis furnace, thereby blocking the distribution plate. Due to the lack of effective solutions in the traditional process, the synthesis furnace is often forced to Parking for maintenance

(3) Long-term operation is difficult, resulting in a large workload for production maintenance

Therefore, in order to reduce the cost increase caused by fine silicon powder, the particle size requirements of the raw material silicon powder are very strict, but this also increases the difficulty of industrial silicon powder processing and increases the processing cost

[0004] Industrial silicon powder contains a small amount of inert components (mainly in the form of silicon dioxide), and because industrial silicon powder contains a small amount of water, this part of water interacts with silicon powder in the fluidized reaction bed to cause some silicon powder Deactivation, inert components accumulate in the fluidized bed of the synthesis furnace because they cannot react with hydrogen chloride, resulting in a decrease in the effective silicon content in the fluidized bed, poor fluidization reaction, and affecting the conversion rate of trichlorosilane

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