Tail gas protective cover of polycrystalline silicon reduction furnace, polycrystalline silicon reduction furnace and polycrystalline silicon production system

Abstract

The utility model relates to a polycrystalline silicon reduction furnace tail gas protective cover, a polycrystalline silicon reduction furnace and a polycrystalline silicon production system. The protective cover comprises a cylindrical side wall and a top cover, the top end of the cylindrical side wall is connected with the top cover, and the bottom end of the cylindrical side wall is connected with a tail gas outlet; a plurality of air inlet through holes which are uniformly distributed in the circumferential direction are formed in the cylindrical side wall; an exhaust through hole is formed in the circle center of the top cover. Compared with the prior art, the exhaust through hole increases the flow of a gas field at the top of the polycrystalline silicon reduction furnace tail gas protective cover, reduces the silicon bonding condition at the top of the polycrystalline silicon reduction furnace tail gas protective cover in a high-temperature gas field, and also can prevent the accumulation of silicon powder at the top of the polycrystalline silicon reduction furnace tail gas protective cover when the silicon powder in the gas field circulates downwards out of the tail gas hole.

Description

Technical Field

[0001] The utility model relates to the technical field of polysilicon production equipment, and in particular to a polysilicon reduction furnace tail gas protection cover, a polysilicon reduction furnace and a polysilicon production system. Background Technique

[0002] Electronic-grade polysilicon material is an indispensable raw material in many high-tech electronic information industries. Electronic-grade polysilicon can not only be applied to solar photovoltaic cells but also be widely used in semiconductor devices such as integrated circuits, playing an irreplaceable role. During the production process of electronic-grade polysilicon, the reduction furnace in the reduction system is an important component. High-purity trichlorosilane and hydrogen react in the reduction furnace at a certain temperature to deposit polysilicon on the silicon core to prepare polysilicon. High-purity trichlorosilane and hydrogen continuously enter the reduction furnace through the intake device of the reduction furnace in a certain ratio, while the reduction tail gas (mainly composed of hydrogen, dichlorosilane, trichlorosilane, tetrachlorosilane, amorphous silicon, hydrogen chloride, etc.) enters the tail gas recovery device through the tail gas outlet of the reduction furnace. When the reduction furnace reaches the shutdown condition, after cooling and purging the reduction furnace, the silicon rods in it are harvested.

[0003] Generally, the tail gas outlet of the reduction furnace is located in the center of the reduction furnace chassis. During the harvesting process of the reduction furnace, once the silicon blocks fall, they will directly fall into the tail gas pipeline from the tail gas outlet, causing blockage of the tail gas pipeline. In the next batch operation, it will cause problems such as unsmooth tail gas emission and pressure fluctuation of the reduction furnace. To prevent the accumulation of fallen silicon blocks from causing blockage of the tail gas pipeline, it is necessary to regularly disassemble and clean the tail gas pipeline of the reduction furnace. Once there is residual chlorosilane material in the pipeline, there are safety risks during the cleaning process. At the same time, the tail gas pipeline belongs to the first-level cleaning pipeline. Frequent disassembly and maintenance will pollute the tail gas system and directly affect the quality of polysilicon products.

[0004] Currently, the main methods for intercepting tail gas in the polysilicon reduction furnace mainly include using a molybdenum alloy tail gas cover. This kind of tail gas cover is expensive, and its structure and air flow channel do not have the function of intercepting silicon powder and silicon blocks in the air flow, and the pipeline facilities and equipment are still severely worn. Another method is to configure alloy or stainless steel components with a mesh structure to cover the tail gas holes, but this also has problems such as being easily corroded, short service life, frequent replacement, frequent maintenance, and affecting production efficiency.

[0005] The Chinese patent with the announcement number CN209065431U and the announcement date of July 5, 2019 discloses a tail gas protective cover for a polysilicon reduction furnace. The protective cover includes a cylindrical side wall, the top end of the cylindrical side wall is connected to a closed top cover, and the lower end of the cylindrical side wall is connected to a tail gas outlet; a plurality of exhaust through holes evenly distributed in the circumferential direction are provided on the cylindrical side wall; the protective cover is a carbon-carbon composite material protective cover. When this tail gas protective cover is used, it is easy to cause silicon powder accumulation and silicon coking above the top cover. The accumulated silicon powder cannot react with the gas, or is carried into the tail gas pipe by the gas flow, affecting the quality of polysilicon products. Summary of the Invention

[0006] The technical problem to be solved by the present utility model is that when the existing protective cover is used, it is easy to cause silicon powder accumulation and silicon coking above the top cover. The accumulated silicon powder cannot react with the gas, or is carried into the tail gas pipe by the gas flow, affecting the quality of polysilicon products.

[0007] To solve the above technical problem, according to one aspect of the present utility model, there is provided a tail gas protective cover for a polysilicon reduction furnace, wherein the protective cover includes a cylindrical side wall and a top cover. The top end of the cylindrical side wall is connected to the top cover, and the bottom end of the cylindrical side wall is connected to a tail gas outlet;

[0008] A plurality of intake through holes evenly distributed in the circumferential direction are provided on the cylindrical side wall;

[0009] An exhaust through hole is provided at the center of the top cover.

[0010] Preferably, the diameter of the top cover is equal to the outer diameter of the cylindrical side wall.

[0011] Preferably, the intake through hole is rectangular.

[0012] Preferably, the exhaust through hole is circular.

[0013] Preferably, the protective cover further includes a tail gas pipe interface, and the tail gas pipe interface is fixedly connected to the bottom end of the cylindrical side wall.

[0014] Preferably, the outer diameter of the cylindrical side wall is greater than the outer diameter of the tail gas pipe interface.

[0015] Preferably, the cylindrical side wall, the top cover and the tail gas pipe interface are integrated.

[0016] Preferably, the cylindrical side wall, the top cover and the tail gas pipe interface are combined.

[0017] According to the second aspect of the present utility model, there is provided a polysilicon reduction furnace including the above-mentioned tail gas protective cover for a polysilicon reduction furnace.

[0018] According to the third aspect of the present utility model, a polysilicon production system is provided, which includes the above-mentioned polysilicon reduction furnace.

[0019] Compared with the prior art, the technical solutions provided by the embodiments of the present utility model can at least achieve the following beneficial effects:

[0020] First, the exhaust through-holes increase the flow of the gas field at the top of the polysilicon reduction furnace tail gas protection cover, reduce the silicon deposition at the top of the polysilicon reduction furnace tail gas protection cover in the high-temperature gas field, and can also prevent the accumulation of silicon powder at the top of the polysilicon reduction furnace tail gas protection cover when the silicon powder in the gas field circulates downward through the tail gas holes.

[0021] Second, in the polysilicon reduction furnace, trichlorosilane and hydrogen are mixed and heated and then sprayed out from the feed hole. When reaching the top, after being blocked by the silicon rods on the furnace wall and the feed air flow of other nozzles, they enter the tail gas pipe through the intake through-holes, slowing down the residence time of the gas flow in the furnace, increasing the efficiency of material reaction and decomposition, and secondly reducing the erosion of the high-temperature gas flow and silicon powder on the tail gas pipe.

[0022] Third, a plurality of circumferentially evenly distributed intake through-holes are provided on the cylindrical side wall, and an exhaust through-hole is provided at the center of the top cover. The polysilicon reduction furnace tail gas protection cover not only prevents silicon blocks from falling into the reduction furnace tail gas pipeline, but also ensures the normal circulation of the reduction furnace tail gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the drawings of the embodiments will be briefly introduced below. Obviously, the drawings described below only relate to some embodiments of the present utility model and do not limit the present utility model.

[0024] Figure 1 It is a schematic structural diagram of a polysilicon reduction furnace tail gas protection cover provided for this embodiment;

[0025] Figure 2 For Figure 1 The developed schematic diagram of the described cylindrical side wall. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] In order to make the objectives, technical solutions, and advantages of the embodiments of the present utility model clearer, the technical solutions of the embodiments of the present utility model will be clearly and completely described below with reference to the drawings of the embodiments of the present utility model. Obviously, the described embodiments are some, but not all, of the embodiments of the present utility model. All other embodiments obtained by those of ordinary skill in the art based on the described embodiments of the present utility model without creative efforts shall fall within the protection scope of the present utility model.

[0027] Unless otherwise defined, the technical terms or scientific terms used herein shall have the ordinary meanings as understood by those of ordinary skill in the art to which the present utility model pertains. The terms "first", "second" and similar terms used in the description and claims of the patent application of the present utility model do not denote any order, quantity or importance, but are only used to distinguish different components. Similarly, terms such as "a" or "an" do not denote a quantity limitation, but mean that there is at least one.

[0028] Reference Figure 1 and Figure 2 In one aspect, this embodiment provides a tail gas protection cover for a polysilicon reduction furnace. The protection cover includes a cylindrical side wall 1, a top cover 2 and a tail gas pipe interface 4. The top end of the cylindrical side wall 1 is connected to the top cover 2, and the tail gas pipe interface 4 is fixedly connected to the bottom end of the cylindrical side wall 1. The tail gas pipe interface 4 is connected to a tail gas outlet.

[0029] Among them, the cylindrical side wall 1, the top cover 2 and the tail gas pipe interface 4 can be combined or integrated. Preferably, the cylindrical side wall 1, the top cover 2 and the tail gas pipe interface 4 are integrated.

[0030] Preferably, the tail gas protection cover for the polysilicon reduction furnace is a carbon-carbon composite material, which can withstand high temperatures, resist corrosion, has high strength, extends the service life, and reduces the maintenance and replacement costs.

[0031] A plurality of intake through holes 3 are circumferentially and uniformly arranged on the cylindrical side wall 1. In this embodiment, the outer diameter of the cylindrical side wall 1 is 340 mm and the height is 150 mm; the number of the intake through holes 3 is four. The intake through holes are rectangular, the arc length of the intake through holes is 140 mm, and the height is 100 mm; the circumferential arc length between adjacent intake through holes is 67 mm.

[0032] The diameter of the top cover 2 is equal to the outer diameter of the cylindrical side wall 1. An exhaust through hole 5 is provided at the center of the top cover 2. The exhaust through hole 5 increases the flow of the gas field at the top of the tail gas protection cover of the polysilicon reduction furnace, reduces the silicon deposition at the top of the tail gas protection cover of the polysilicon reduction furnace in the high-temperature gas field, and can also prevent the accumulation of silicon powder at the top of the tail gas protection cover of the polysilicon reduction furnace when the silicon powder in the gas field circulates downward through the tail gas holes. Preferably, the thickness of the top cover 2 is 15 mm; the exhaust through hole 5 is circular with a diameter of 8 mm.

[0033] Preferably, the length of the tail gas pipe interface 4 is 30 mm and the outer diameter is 258 mm. The outer diameter of the cylindrical side wall 1 is larger than the outer diameter of the tail gas pipe interface 4, which is equivalent to that there is a step at the connection between the tail gas interface 4 and the cylindrical side wall 1.

[0034] The usage method of the polysilicon reduction furnace tail gas protection cover is as follows: insert the tail gas pipe interface 4 into the tail gas pipe. A plurality of intake through holes 3 are circumferentially and uniformly arranged on the cylindrical side wall 1; an exhaust through hole 5 is provided at the center of the top cover 2. Compared with the prior art, the polysilicon reduction furnace tail gas protection cover not only prevents silicon blocks from falling into the reduction furnace tail gas pipeline, but also ensures the normal circulation of the reduction furnace tail gas.

[0035] In the second aspect of this embodiment, a polysilicon reduction furnace is provided, which includes the above-mentioned polysilicon reduction furnace tail gas protection cover. Compared with the prior art, in the reduction furnace, trichlorosilane and hydrogen are mixed and heated and then ejected from the feed hole. After reaching the top and being blocked by the silicon rods on the furnace wall and the feed air flow of other nozzles, they enter the tail gas pipe through the intake through holes 3, which slows down the residence time of the air flow in the furnace, increases the efficiency of material reaction and decomposition, and secondly reduces the erosion of the high-temperature air flow and silicon powder on the tail gas pipe.

[0036] In the third aspect of this embodiment, a polysilicon production system is provided, which includes the above-mentioned polysilicon reduction furnace.

[0037] The above is only an exemplary implementation manner of the present invention, rather than being used to limit the protection scope of the present invention. The protection scope of the present invention is determined by the appended claims.

Claims

1. A tail gas protection cover for a polysilicon reduction furnace, characterized in that The protective cover includes a cylindrical side wall and a top cover. The top end of the cylindrical side wall is connected to the top cover, and the bottom end of the cylindrical side wall is connected to the tail gas outlet. A plurality of intake through holes are circumferentially and evenly arranged on the cylindrical side wall. An exhaust through hole is provided at the center of the top cover.

2. The tail gas protection cover of the polysilicon reduction furnace according to claim 1, wherein The diameter of the top cover is equal to the outer diameter of the cylindrical side wall.

3. The tail gas protection cover of the polysilicon reduction furnace according to claim 1, characterized in that, The intake through holes are rectangular.

4. The polysilicon reduction furnace tail gas protection cover according to claim 1, characterized in that, The exhaust through hole is circular.

5. The tail gas protection cover of the polysilicon reduction furnace according to claim 1, characterized in that The protective cover further includes a tail gas pipe interface, which is fixedly connected to the bottom end of the cylindrical side wall.

6. The tail gas protection cover of the polysilicon reduction furnace according to claim 5, characterized in that, The outer diameter of the cylindrical side wall is greater than the outer diameter of the tail gas pipe interface.

7. The tail gas protection cover of the polysilicon reduction furnace according to claim 5, characterized in that, The cylindrical side wall, the top cover and the tail gas pipe interface are integrated.

8. The tail gas protection cover of the polysilicon reduction furnace according to claim 5, characterized in that The cylindrical side wall, the top cover and the tail gas pipe interface are combined.

9. A polysilicon reduction furnace, characterized in that, A tail gas protective cover for a polysilicon reduction furnace according to any one of claims 1 to 8.

10. A polysilicon production system, characterized in that, A polysilicon reduction furnace including the protective cover according to claim 9.

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