Bell jar type silicon particle cooling tank

Abstract

The utility model discloses a bell jar type silicon particle cooling tank, including the tank body that adopts the combination of bell jar and bottom disc, be equipped with cooling system on the tank body, be equipped with feed inlet and gas outlet on the bell jar, be equipped with the feed system of blowing purging gas to the tank body in the discharge port and on the bottom disc, cooling system includes the cooling jacket of being equipped with the bell jar outer wall, and is equipped with the cooling coil of bottom disc lower part, the utility model discloses the combination of bell jar and bottom disc forms the bell jar type structure of separable, and the thorough cleaning in the tank is convenient for realizing, and through the combination of feed system, cooling jacket and cooling coil, realizes the combination of gas cooling and water cooling, can not only realize the even, efficient cooling of silicon particle inside and outside, and because its internal structure is simple, fundamentally avoids the silicon problem, and has the dual advantages of efficient cooling and convenient maintenance.

Description

Technical Field

[0001] This utility model relates to a bell-shaped silicon particle cooling tank, specifically to a cooling device suitable for particulate silicon in polycrystalline silicon production, belonging to the field of polycrystalline silicon production technology. Background Technology

[0002] Vapor deposition is a key process for preparing high-purity silicon particles. Its principle involves introducing a gaseous silane compound at high temperature into a reactor (such as a fluidized bed reactor) containing fine silicon seed crystals. The gas reacts chemically on the seed crystal surface, precipitating solid silicon and thus obtaining silicon particles. This process typically involves reactions exceeding 500°C, and the resulting silicon particles must be cooled before subsequent transport and storage. Directly processing the high-temperature silicon particles not only increases the risk of product contamination due to thermal stress, affecting product quality, but also results in significant energy waste. Therefore, efficient cooling of the silicon particles after vapor deposition is crucial.

[0003] Currently, gas cooling is commonly used in the cooling process of granular silicon, and dry gases must be used to prevent silicon particle oxidation or hydrolysis. There are two main types of commonly used cooling gases: one is hydrogen, which is a process gas within the reactor, has good compatibility with silicon particles, and will not introduce additional contamination to the reaction system should backflow occur during unloading; the other is inert gases such as argon, which, although inert to silicon particles, is less commonly used in practice due to difficulties in recycling within the system and the need for additional separation and processing steps. Furthermore, it also requires preventing backflow into the reactor during unloading. Therefore, considering process compatibility and operational convenience, hydrogen is the more commonly used cooling medium.

[0004] In existing technologies, cooling of granular products typically employs water cooling, air cooling, or a combination thereof. However, considering the specific production processes and cooling efficiency requirements of granular silicon, existing cooling devices often fall short of meeting these process demands.

[0005] Taking Chinese patent CN219454437U as an example, this patent discloses a continuous cooling device for easily deliquescent granules, including a feeding hopper, a cooling tank, and a discharging hopper. The upper part of the cooling tank's inner cavity is equipped with a material distributor, the middle part with cooling coils and upper, middle, and lower three-layer gas distributors, enabling simultaneous air-cooling and water-cooling circulation. A discharge port is located at the bottom of the tank. However, this device has a large number of heat exchange tubes, and silicon particles are prone to colliding with the tubes during their descent, potentially causing product contamination and posing risks of tube damage and leakage. Furthermore, the bottom of the device primarily relies on air cooling, resulting in a slow cooling rate.

[0006] Another example is a solid particle cooler disclosed in Chinese patent CN208920901U, which includes a shell and multiple tube bundle assemblies. The shell has an exhaust port and an inlet at the top, and an outlet at the bottom. The tube bundle assemblies are assembled inside the shell, including a sleeve-type header located in the upper section of the shell and several downward-extending heat exchange tube units connected to it, with saturated boiler water flowing inside the tubes. High-temperature solid particles enter through the inlet, exchange heat with the heat exchange tube units to cool down, and are finally discharged through the outlet. The top of the shell also has a cooler distribution pipe, cooling pipes, and cooling coils. Auxiliary cooling is typically activated when the temperature of the inlet particles exceeds 800°C to ensure smooth downward flow and discharge of the particles. This structure also suffers from the problem of densely packed internal heat exchange tubes, making it easy for silicon particles to impact the tubes when falling, potentially leading to contamination or equipment damage.

[0007] In summary, existing particle cooling technologies still have significant limitations. First, the complex internal heat exchange components are prone to particle contamination and equipment damage. Second, the dense tube bundles and distributors create cleaning dead zones inside the tank, making operation and maintenance difficult. Utility Model Content

[0008] The purpose of this invention is to provide a bell-shaped silicon particle cooling tank. The bell and the base are combined to form a separable bell-shaped structure, which facilitates thorough cleaning of the tank. At the same time, the combination of air intake system, cooling jacket and cooling coil realizes the combination of air cooling and water cooling. It can not only achieve uniform and efficient cooling of silicon particles inside and out, but also fundamentally avoid silicon accumulation problems due to its simple internal structure. It has the dual advantages of efficient cooling and easy maintenance.

[0009] This utility model is achieved through the following technical solution: a bell-shaped silicon particle cooling tank, comprising a tank body formed by connecting a bell and a chassis, a cooling system on the tank body, a feed inlet and an air outlet on the bell, and a discharge outlet and an air inlet system for blowing gas into the tank body on the chassis; the cooling system includes a cooling jacket on the outer wall of the bell and a cooling coil on the lower part of the chassis.

[0010] The air intake system includes several air intake holes on the chassis and nozzles connected to the air intake holes. The nozzles are set perpendicular to the chassis and have several nozzles on their side walls.

[0011] The air intake holes are evenly distributed in at least one ring around the circumference of the chassis, with at least four air intake holes in each ring. The number of air intake holes in each ring may be equal or unequal.

[0012] The nozzle is detachably connected to the air inlet via a threaded structure.

[0013] A protective net is installed around the nozzle.

[0014] The bell jar and the chassis are fastened together by bolts, and a sealing gasket is provided at the connection.

[0015] The cooling system also includes a gasket cooling pipe for cooling the sealing gasket.

[0016] The bell jar is equipped with at least one observation mirror, and a hydrogen purging port is configured in the pipe of the observation mirror.

[0017] The bell jar and chassis on the inner wall of the corresponding tank are both coated with silicon carbide.

[0018] The cooling jacket is equipped with a jacket water inlet pipe and a jacket water return pipe, and an exhaust valve is installed on the jacket water return pipe.

[0019] Compared with the prior art, this utility model has the following advantages and beneficial effects: (1) The tank of this utility model adopts a modular structure in which the bell jar and the chassis can be separated and fastened by bolt assembly, which can make the inside of the tank completely open. This fundamentally solves the industry problem that it is difficult to clean the silicon accumulation inside complex containers (with many internal heat exchange tube bundles). It can achieve thorough cleaning of silicon accumulation in every corner of the tank, greatly ensuring the purity of the product and the quality stability between batches.

[0020] (2) This utility model uses multiple cooling methods at different locations on the tank in synergy: First, the silicon material is purged by air cooling through multiple rings of nozzles evenly distributed around the circumference of the chassis inside the tank, achieving bottom-up penetrating cooling; Second, indirect water cooling is achieved through the cooling jacket on the outer wall of the bell jar; Third, the heat exchange in the bottom area is enhanced by the cooling coil at the bottom of the chassis. Based on the combination of air cooling and water cooling, and internal and external cooling methods, the cooling efficiency and uniformity of the silicon particles inside the tank can be effectively guaranteed.

[0021] (3) This utility model greatly simplifies the spatial structure inside the tank. There are no complex components inside, and the silicon particles fall smoothly, which not only effectively avoids the risk of silicon particle contamination and equipment damage caused by collision.

[0022] (4) The design of this utility model is reasonable. The nozzle adopts a detachable design. Its nozzle is located on the side wall or a protective net can be set up, which can prevent silicon particles from entering the air inlet pipe, prevent blockage, and facilitate maintenance. It is equipped with an observation sight glass and a hydrogen purging interface, which facilitates observation of the working conditions inside the tank and keeps the sight glass clear, which can improve the safety of operation and realize safety monitoring.

[0023] (5) The structure of this utility model is reliable. By setting a sealing gasket at the connection of the tank body and setting a special gasket cooling pipe, the sealing reliability at high temperature can be ensured and the service life of the sealing parts can be extended. The bell cover and the inner wall of the chassis are coated with silicon carbide, which can effectively improve the wear resistance and corrosion resistance of the equipment under high temperature conditions. Attached Figure Description

[0024] Figure 1This is a schematic diagram of the structure of this utility model.

[0025] Figure 2 This is a schematic diagram of the chassis structure of this utility model.

[0026] Figure 3 This is a schematic diagram of the nozzle structure of this utility model.

[0027] Figure 4 This is a schematic diagram of the structure of the protective net of this utility model.

[0028] Among them, 1—bell jar, 2—chassis, 3—feed inlet, 4—air outlet, 5—discharge outlet, 6—cooling jacket, 7—air inlet hole, 8—spray head, 9—nozzle, 10—threaded structure, 11—protective net, 12—bolt assembly, 13—sealing gasket, 14—observation sight glass, 15—jacket water supply pipe, 16—jacket water return pipe, 17—exhaust valve, 18—gasket water supply pipe, 19—gasket water outlet pipe, 20—chassis water supply pipe, 21—chassis water outlet pipe, 22—inner ring air inlet pipe, 23—outer ring air inlet pipe. Detailed Implementation

[0029] The present invention will be further described in detail below with reference to the embodiments, but the implementation of the present invention is not limited thereto.

[0030] Example 1: This embodiment is a bell-shaped silicon particle cooling tank, which solves the problems of particle contamination, equipment damage and difficulty in cleaning silicon deposits caused by the complexity of internal heat exchange components in existing cooling containers. The tank body adopts a separable assembly structure consisting of a bell jar 1 and a chassis 2, which can achieve thorough cleaning of silicon deposits inside the tank. At the same time, the internal design of the tank body abandons the existing complex heat exchange tube bundle design. By setting a cooling jacket 6 on the outer wall of the bell jar 1 and setting a cooling coil at the bottom of the chassis 2, combined with the air intake system of the chassis 2, a synergistic cooling system from the outside to the inside and from the bottom to the top is constructed, thereby achieving multi-directional and efficient cooling of silicon particles. It has the advantages of simple structure, high cooling efficiency and easy maintenance.

[0031] like Figure 1As shown, the bell-type silicon particle cooling tank of this embodiment mainly consists of a bell 1, a base 2, and a cooling system. The bell 1 and the base 2 are connected to each other, forming the basic structure of the bell-type tank. Specifically, flanges can be welded to the mating edges of the bell 1 and the base 2, and then these flanges are fastened with bolt assemblies 12 to achieve reliable assembly and sealing of the entire tank. Sealing gaskets 13 can also be used between the flanges fastened by the bolt assemblies 12, such as fluororubber gaskets 13. The size of the sealing gasket 13 is set according to the cross-sectional diameter of the tank, aiming to seal the upper (bell 1) and lower (base 2) parts of the tank when fastened with bolt assemblies 12. A gasket cooling pipe is also provided at the sealing gasket 13, allowing the gasket to be cooled directly by water. Figure 1 In the process, the gasket water enters through the gasket water inlet pipe 18, cools the sealing gasket 13, and is then sent out through the gasket water outlet pipe 19. Circulating water can be used for cooling. Typically, the inlet water temperature is controlled at 33-35℃, and the return water temperature is controlled below 50℃. According to process requirements, this part of the heat is no longer recovered and utilized.

[0032] The bell jar 1 is located on the upper part of the chassis 2. A feed inlet 3 is provided at the center of the top of the bell jar 1, and an outlet 4 is provided on the upper part of the bell jar 1. The bell jar 1 is also equipped with at least one observation mirror 14, and a hydrogen purging port is configured within the connecting pipe of the observation mirror 14. Figure 1 In the middle, two observation mirrors 14 are respectively provided on the upper and lower parts of the bell jar 1 to facilitate observation of the accumulation of silicon particles at different heights inside the tank. The base 2 has a horizontal disc-shaped structure, with a discharge port 5 at the center of the base 2. The base 2 is also equipped with an air intake system, which blows hydrogen gas into the tank from bottom to top to cool the silicon particles. Figure 2 and Figure 3 As shown, the air intake system includes a plurality of air intake holes 7 disposed on the chassis 2 and nozzles 8 connected to the air intake holes 7. The nozzles 8 are disposed perpendicular to the chassis 2 and have a plurality of nozzles 9 disposed on the side wall of the nozzles 8. In this embodiment, the air intake holes 7 are evenly distributed in at least one ring around the circumference of the chassis 2, and the number of air intake holes 7 in each ring is at least 4. The number of air intake holes 7 in each ring may be equal or unequal.

[0033] In a specific implementation case, it can be like this Figure 1 and Figure 2As shown, the air inlet 7 is configured as two concentric rings, with four air inlets 7 in the inner ring, intaked through the inner ring air inlet pipe 22, and eight air inlets 7 in the outer ring, intaked through the outer ring air inlet pipe 23. The nozzle 8 is cylindrical, without an outlet at the top. Several nozzles 9 are located on the sidewall of the nozzle 8. The nozzle 8 is fixed and assembled with the air inlets 7 via a threaded structure 10 at its bottom, facilitating assembly and disassembly. Depending on the area of ​​the chassis 2 and the silicon particle cooling process requirements, the diameter of the air inlet 7 can be set to φ50–100 mm. The height of the nozzle 8 matches the height of the tank, typically set to 0.01–0.5 times the tank height. The nozzles 9 exhaust air from the side, evenly distributed on the side of the nozzle 8. The diameter of the nozzles 9 is controlled between φ2 and 10 mm. Each nozzle 8 has at least 25 openings, which can be adjusted according to the number of air inlets 7 and the silicon material cooling requirements. A protective cover can be fitted tightly against the wall of the nozzle 8 (see [reference]). Figure 4 To protect the nozzle 8, the mesh diameter of the protective mesh 11 is set according to the particle size of the silicon particles, usually between 1 and 2 mm.

[0034] The cooling system in this embodiment includes a cooling jacket 6 and cooling coils. For example... Figure 1 As shown, the cooling jacket 6 is located on the outer wall of the bell jar 1. The cooling jacket 6 is equipped with a jacket water inlet pipe 15 and a jacket water return pipe 16. The jacket cooling water cools the silicon particles inside the bell jar 1 from bottom to top. An exhaust valve 17 is installed at the highest point of the jacket water return pipe 16 to prevent the accumulation of non-condensable gases. The jacket cooling water is cooled using a circulation system of water tank, pump, cooling jacket 6, and water tank. The heat carried away by the jacket cooling water can be reused in other processes of the system. The cooling coil is located at the lower part of the chassis 2, as shown... Figure 1 In the process, the chassis cooling water is cooled by the chassis water inlet pipe 20 and then sent out by the chassis water outlet pipe 21. Its circulation method is the same as that of the jacket cooling water, which can be drawn from the same water tank.

[0035] In a specific implementation case, the jacket water supply temperature is controlled at 30-35℃, the jacket water return temperature is controlled at 45-50℃, the chassis water supply temperature is controlled at 30-35℃, and the chassis water outlet temperature is controlled at 45-50℃.

[0036] In the tank design of this embodiment, to reduce contamination of silicon particles by impurities, silicon carbide spraying can be applied to the inner wall of the tank (including the inner side of the bell jar 1 and the chassis 2), with a silicon carbide coating thickness of approximately 2-5 mm. The outer surfaces of the nozzle 8 and the protective mesh 11 can also be treated with silicon carbide spraying. In actual production, the tank size is usually not strictly limited and can be flexibly designed according to the silicon particle production rate (i.e., production load) to meet the cooling requirements of the silicon particles inside the tank. It is recommended that the material level inside the tank be controlled at a maximum of 70% to reserve a certain emergency buffer space. The tank diameter should preferably be controlled within the range of 1-2 m, and the ratio of tank height to diameter should preferably be maintained between 1:1 and 8:1. If the diameter is too large, the jacket water may not be able to cool the silicon particles sufficiently; if the height is too high, the hydrogen flow path inside the tank will be too long, and the temperature will be high when it reaches the top of the tank, which will affect the cooling effect of the silicon particles at the top. Both of the above situations may lead to a decrease in the silicon particle cooling rate.

[0037] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present utility model shall fall within the protection scope of the present utility model.

Claims

1. A bell-shaped silicon particle cooling tank, characterized in that: The tank is formed by connecting a bell jar (1) and a chassis (2). A cooling system is provided on the tank. The bell jar (1) is provided with a feed inlet (3) and an air outlet (4). The chassis (2) is provided with a discharge outlet (5) and an air intake system for blowing gas into the tank. The cooling system includes a cooling jacket (6) provided on the outer wall of the bell jar (1) and a cooling coil provided on the lower part of the chassis (2).

2. The bell-shaped silicon particle cooling tank according to claim 1, characterized in that: The air intake system includes several air intake holes (7) on the chassis (2) and nozzles (8) connected to the air intake holes (7). The nozzles (8) are set perpendicular to the chassis (2) and several nozzles (9) are provided on the side wall of the nozzles (8).

3. The bell-shaped silicon particle cooling tank according to claim 2, characterized in that: The air inlets (7) are evenly distributed around the circumference of the chassis (2) at least once, with at least 4 air inlets (7) in each circle, and the number of air inlets (7) in each circle may be equal or different.

4. The bell-shaped silicon particle cooling tank according to claim 2, characterized in that: The nozzle (8) is detachably connected to the air inlet (7) via a threaded structure (10).

5. The bell-shaped silicon particle cooling tank according to claim 2, characterized in that: A protective net (11) is installed outside the nozzle (8).

6. The bell-shaped silicon particle cooling tank according to claim 1, characterized in that: The connection between the bell jar (1) and the chassis (2) is fastened by bolt assembly (12), and a sealing gasket (13) is provided at the connection.

7. The bell-shaped silicon particle cooling tank according to claim 6, characterized in that: The cooling system also includes a gasket cooling pipe for cooling the sealing gasket (13).

8. The bell-shaped silicon particle cooling tank according to claim 1, characterized in that: The bell jar (1) is provided with at least one observation mirror (14), and a hydrogen purging port is configured in the pipe of the observation mirror (14).

9. The bell-shaped silicon particle cooling tank according to claim 1, characterized in that: The bell jar (1) and the chassis (2) on the inner wall of the corresponding tank are both coated with silicon carbide.

10. The bell-shaped silicon particle cooling tank according to claim 1, characterized in that: The cooling jacket (6) is provided with a jacket water inlet pipe (15) and a jacket water return pipe (16), and an exhaust valve (17) is provided on the jacket water return pipe (16).

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