High efficiency cold hydrogenation fluidized bed reactor

Abstract

A high-efficiency cold hydrogenation fluidized bed reactor is characterized by comprising a lower head, a cylinder and an upper head; a material inlet is arranged at the bottom of the lower head, and a gas distributor is arranged above the material inlet; a mixture of silicon tetrachloride and hydrogen enters from the material inlet and is uniformly distributed through the gas distributor; a silicon powder inlet, a silicon powder outlet and a plurality of bubble breakers are arranged above the gas distributor. By symmetrically arranging guide vanes, the airflow forms an "eight" symmetrical direction flow in a single grid block and forms a rotating flow between multiple grid blocks; the reverse arrangement of the guide vanes of the upper and lower bubble breakers makes the bubbles form a rotating cutting when passing through the grid block, which can effectively reduce the diameter of the bubbles and prevent the gas from re-agglomerating into bubbles along the vertical direction after breaking; meanwhile, the residence time of the material can be increased, and the turbulent flow degree of the material in the reactor can be increased, so that the flow field in the cold hydrogenation fluidized bed reactor can be improved, and the conversion efficiency of trichlorosilane can be improved.

Description

Technical Field

[0001] This invention relates to a fluidized bed reactor, and more particularly to a fluidized bed reactor for producing trichlorosilane by cold hydrogenation, which has a high efficiency in defoaming, improves the gas-solid contact level, and effectively improves production efficiency. Specifically, it is a high-efficiency cold hydrogenation fluidized bed reactor. Background Technology

[0002] The silicon wafers used in solar photovoltaic panels are made from high-purity polycrystalline silicon. The production of polycrystalline silicon generates a large amount of highly toxic silicon tetrachloride, which not only harms the environment but also wastes a significant amount of raw materials and increases the production cost of polycrystalline silicon. Silicon tetrachloride processing technologies mainly focus on two directions: one is to prepare silicon tetrachloride into other chemicals, such as fumed silica, organosilicon products, and optical fibers; the other is to produce trichlorosilane. However, the market demand for the former is limited, and silicon tetrachloride cannot be processed in large quantities. Trichlorosilane, as a raw material for polycrystalline silicon production, is not limited by processing volume. Therefore, the hydrogenation of silicon tetrachloride to produce trichlorosilane has become the mainstream method. The cold hydrogenation process is widely used due to its low reaction temperature, high conversion rate, and low operating cost. The cold hydrogenation process involves reacting silicon powder, hydrogen, and silicon tetrachloride in a cold hydrogenation reactor at a reaction temperature of 500-600℃, a pressure of 2-4 MPa, and with a catalyst to generate trichlorosilane. This not only achieves the recycling of silicon tetrachloride but also significantly reduces production costs for enterprises.

[0003] The cold hydrogenation fluidized bed reactor is the core equipment in the cold hydrogenation process. However, due to the generation of bubbles in the gas-solid two-phase flow, the residence time of particles in the reactor is uneven, and the bed fluctuates frequently, significantly reducing the yield of trichlorosilane. To improve the process, bubble-breaking internals are generally added inside the reactor. Currently, bubble-breaking internals in cold hydrogenation fluidized bed reactors are mainly of three types: horizontal components, vertical components, and composite components. After passing through the horizontal components, the gas breaks large bubbles into strip-shaped bubbles, but they will coalesce again after a certain distance. Although the vertical components have a simple structure, they only restrict bubble growth and have very limited effect on breaking bubbles. Composite components are mostly used in catalytic cracking strippers and regenerators, but due to their overly complex structure, they are not widely used in cold hydrogenation fluidized bed reactors.

[0004] As the capacity and size of cold hydrogenation fluidized bed reactors continue to expand, with diameters reaching over 3.5m and single-unit capacity exceeding 200,000 tons / year, improper arrangement of defoamers can lead to poor defoaming effects, thereby significantly reducing the production of trichlorosilane. Summary of the Invention

[0005] The purpose of this invention is to address the problem of reduced yield in existing reactors due to unreasonable bubble breaker design. This invention designs a high-efficiency cold hydrogenation fluidized bed reactor. By arranging several guide vanes with different directions, the airflow forms a symmetrical flow within a single grid block and a rotating flow between multiple grid blocks. The reverse arrangement of the upper and lower layers of bubble breaker guide vanes significantly increases the vertical travel of the airflow, effectively reducing the bubble diameter and improving gas-solid contact. Simultaneously, it increases the material residence time and the turbulence within the reactor, thereby improving the flow field within the cold hydrogenation reactor and increasing the conversion efficiency of trichlorosilane.

[0006] The technical solution adopted in this invention is as follows:

[0007] A high-efficiency cold hydrogenation fluidized bed reactor is characterized in that the fluidized bed reactor is arranged vertically and consists of a lower head 1, a cylinder 2, and an upper head 5; a material inlet 9 is arranged at the bottom of the lower head 1 and a gas distributor 3 is arranged above the material inlet 9. A mixture of silicon tetrachloride and hydrogen enters from the material inlet 9 and is evenly distributed by the gas distributor 3.

[0008] The gas distributor 3 is equipped with a silicon powder inlet 7, a silicon powder outlet 8, and a bubble breaker 4. The bubble breaker 4 is located above the silicon powder inlet 7, and a material outlet 6 is located above the bubble breaker. The bubble breaker 4 is composed of several grid blocks 10. Each grid block 10 consists of an outer baffle 11, a middle baffle 12, and guide vanes 13. The middle baffle 12 divides the grid block into multiple cuboid spaces. The guide vanes 13 are obliquely welded between the outer baffle 11 and the middle baffle 12 or between the middle baffle 12. The guide vanes 13 in the same cuboid space have the same oblique direction, and the guide vanes 13 on both sides of the middle baffle 12 are symmetrically arranged. Multiple holes are opened in the outer baffle 11 around the perimeter, and they are connected to adjacent grid blocks by fasteners 14. Multiple grid blocks can be welded together to form a single grid block. The bolts and fasteners 14 are set according to the specific shape of the reactor. The airflow arrangement direction of adjacent grid blocks 10 is at a 90-degree angle, and the arrangement direction of spaced grid blocks 10 is the same.

[0009] The guide vanes 13 are arranged in a spatial arrangement with an angle α of 0 to 45° to the horizontal direction and an angle β of 30 to 75° to the vertical direction, and the length of a single guide vane is 20 to 50 mm.

[0010] In the reactor, the guide vanes 13 of the odd-numbered layers of bubble breakers are consistent, while the guide vanes 13 of the even-numbered layers of bubble breakers at the same position are arranged in opposite directions.

[0011] The number of bubble breakers 4 is 5 to 15 layers, with the lowest bubble breaker being 600 to 2000 mm vertically from the gas distributor; the vertical spacing between adjacent bubble breakers is 500 to 1000 mm.

[0012] The silicon powder inlet 7 is inserted obliquely into the cylinder 2 at an angle of 30° to 70° with the central axis of the reactor, and the material inlet extends 100mm to 400mm into the cylinder 2; a bubble breaker support plate is welded on the cylinder to support the bubble breaker.

[0013] The beneficial effects of this invention are:

[0014] This invention provides a high-efficiency cold hydrogenation fluidized bed reactor. Its bubble breaker is arranged with several guide vanes in different directions, causing the airflow to flow in a symmetrical "figure-eight" direction within a single grid block, and forming a rotating flow between multiple grid blocks. The opposing arrangement of the guide vanes in the upper and lower layers of bubble breakers causes the bubbles to rotate and cut as they pass through the grid blocks, effectively reducing the bubble diameter and thus achieving bubble breaking. It also prevents the gas from re-aggregating into bubbles along the vertical direction after bubble breaking. Simultaneously, this flow pattern enhances the gas-solid contact effect, increases the turbulence of the material within the reactor, and thus improves the conversion rate of silicon tetrachloride. The single-layer grid is composed of identical grid blocks bolted together, allowing for flexible arrangement into various shapes, greatly facilitating processing and installation. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of the high-efficiency cold hydrogenation fluidized bed reactor of the present invention.

[0016] Figure 2 This is a schematic diagram of a single grid block structure according to the present invention.

[0017] Figure 3 This is a schematic diagram of the guide vane arrangement structure of the present invention.

[0018] Figure 4 This is a schematic diagram of the single-layer bubble breaker structure of the present invention.

[0019] In the figure: 1-lower head, 2-cylinder, 3-gas distributor, 4-bubble breaker, 5-upper head, 6-material outlet, 7-silicon powder inlet, 8-silicon powder outlet, 9-material inlet, 10-grid block, 11-outer baffle, 12-middle baffle, 13-guide vane, 14-fastener. Detailed Implementation

[0020] The following description, in conjunction with specific embodiments and accompanying drawings, is intended to further illustrate the invention but is not intended to limit the scope of the invention.

[0021] like Figure 1-4 As shown.

[0022] A high-efficiency cold hydrogenation fluidized bed reactor, with a vertical arrangement, consists of a lower head 1, a cylindrical body 2, and an upper head 5, as shown below. Figure 1As shown; a material inlet 9 is arranged at the bottom of the reactor lower head 1, and a gas distributor 3 is arranged above the material inlet 9. A mixture of silicon tetrachloride and hydrogen enters from the material inlet 9 and is evenly distributed by the gas distributor 3. A silicon powder inlet 7 and a silicon powder outlet 8 are arranged above the gas distributor 3, and a bubble breaker 4 is arranged above the silicon powder inlet 7. A material outlet 6 is provided above the bubble breaker 4. The bubble breaker 4 is composed of several grid blocks 10, such as... Figure 4 As shown, the grid block 10 consists of an outer baffle 11, a middle baffle 12, and guide vanes 13, as... Figure 2 As shown, the intermediate baffle 12 divides the grid blocks into multiple cuboid spaces. Guide vanes 13 are obliquely welded between the outer baffle 11 and the intermediate baffle 12, or between the intermediate baffle 12. The guide vanes 13 within the same cuboid space have the same oblique direction, and the guide vanes 13 on both sides of the intermediate baffle 12 are symmetrically arranged in oblique directions. Multiple holes are opened in the outer baffle 11 around the perimeter, and fasteners 14 are used to connect them to adjacent grid blocks. Multiple grid blocks can be welded together to form a single grid block. The bolts and fasteners 14 are set according to the specific shape of the reactor interior. The airflow arrangement direction of adjacent grid blocks 10 is at a 90-degree angle, and the arrangement direction of spaced-apart grid blocks 10 is the same. The guide vanes 13 are arranged in a spatial arrangement with an angle α of 0~45° to the horizontal direction and an angle β of 30~75° to the vertical direction (e.g., ...). Figure 3 The length of a single guide vane is 20-50mm. In the reactor, the guide vanes 13 of the odd-numbered layers of bubble breakers are identical, while those of the even-numbered layers are arranged in opposite directions at the same position. The optimal number of bubble breakers 4 is 5-15 layers, with the lowest layer of bubble breakers vertically 600-2000mm from the gas distributor; adjacent bubble breakers are spaced 500-1000mm apart vertically. The silicon powder inlet 7 is inserted obliquely into the cylinder 2 at an angle of 30°-70° to the reactor's central axis, and the material inlet extends 100mm-400mm into the cylinder 2. A bubble breaker support plate is welded onto the cylinder to support the bubble breakers.

[0023] The parts not covered in this invention are the same as or can be implemented using existing technologies.

Claims

1. A cold hydrogenation fluidized bed reactor characterized by: The fluidized bed reactor is vertically arranged and consists of a lower head, a cylindrical body, and an upper head. A material inlet is located at the bottom of the lower head, and a gas distributor is positioned above the material inlet. A mixture of silicon tetrachloride and hydrogen enters through the material inlet and is evenly distributed by the gas distributor. Above the gas distributor are a silicon powder inlet, a silicon powder outlet, and a multi-layer debubbler. A material outlet is located at the top of the upper head. The debubbler consists of several grid blocks, each grid block comprising an outer baffle, a middle baffle, and guide vanes. The middle baffle divides the grid block into multiple cuboid spaces, and the guide vanes are obliquely welded between the outer and middle baffles. The guide vanes are inclined and welded between the intermediate baffles; the guide vanes are arranged in a spatial arrangement with an angle α of 0~45° to the horizontal direction and an angle β of 30~75° to the vertical direction, and the length of a single guide vane is 20~50mm; the guide vanes of the odd-numbered layers of bubble breakers in the reactor are consistent, and the guide vanes of the even-numbered layers of bubble breakers at the same position are arranged in opposite directions; the guide vanes of the bubble breakers in the same cuboid space are inclined in the same direction, and the guide vanes on both sides of the intermediate baffle are arranged symmetrically in the direction of inclination; the airflow arrangement direction of the adjacent grid blocks of the bubble breakers is at a 90-degree angle, and the arrangement direction of the grid blocks that are spaced apart is the same.

2. The cold hydrogenation fluid bed reactor of claim 1, wherein: The bubble breakers are arranged above the silicon powder inlet, in at least two layers.

3. The cold hydrogenation fluid bed reactor of claim 2, wherein: The number of layers in the bubble breaker is 5 to 15.

4. The cold hydrogenation fluid bed reactor of claim 1, wherein: The bubble breaker has multiple through holes for fasteners on its outer side baffles. Adjacent grid blocks are connected by fasteners, and multiple grid blocks are welded together to form a single grid block. Bolts and fasteners are set according to the specific shape of the reactor interior.

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