A multi-stage silicon particle cooling device

Abstract

The utility model discloses a kind of multistage silicon particle cooling devices, including umbrella-like distributor, cylindrical heat exchange cylinder and heat exchange tank, silicon particle feed inlet is equipped at umbrella-like distributor top, inside material flow channel is equipped, annular outlet is equipped at bottom;Cylindrical heat exchange cylinder is composed of concentrically arranged outer cylinder and inner cylinder, annular interlayer is formed between outer cylinder and inner cylinder, inside heat exchange jacket is arranged along inner cylinder inner wall, outside heat exchange jacket is arranged along outer cylinder outer wall, annular outlet is communicated with annular interlayer top, annular interlayer bottom is communicated with heat exchange tank top by pipeline;Heat exchange jacket is arranged on the outer wall of heat exchange tank, gas purging port and silicon particle outlet are arranged at bottom, gas outlet is arranged at upper portion.The utility model uses cylindrical heat exchange cylinder and heat exchange tank to cool silicon particle in two stages, cylindrical heat exchange cylinder can realize the jacket cooling of inside and outside double circles, can promote cooling effect, the use of umbrella-like distributor can be realized to make silicon particle can be evenly distributed in annular cylindrical heat exchange cylinder and reduce impact, avoid to cause damage and pollution to silicon particle.

Description

Technical Field

[0001] This utility model relates to a multi-stage silicon particle cooling device, specifically a high-efficiency cooling device for silicon particles in the cooling process of granular silicon production, belonging to the field of polycrystalline silicon production technology. Background Technology

[0002] Vapor deposition for silicon particle preparation involves introducing one or more silicon-containing gaseous compounds (silane gases) into a reactor containing fine silicon seed crystals at high temperatures. The gas reacts chemically on the seed crystal surface, precipitating solid silicon to obtain silicon particles, as seen in fluidized bed reactor (FBR) processes. Silicon particles produced by fluidized bed processes typically reach temperatures above 500°C. Since these high-temperature silicon particles cannot be directly transferred, it not only increases the risk of contamination but may also delay production. Furthermore, the heat cannot be recovered, resulting in energy waste. Therefore, cooling the silicon particles prepared by 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 the prior art, Chinese patent CN114963782A discloses a solid particle cooler for cooling devices of granular products. The inner cavity of the cooler is arranged from top to bottom as a material distribution mechanism, several heat exchange units and a discharge unit. The heat exchange unit consists of two headers arranged opposite each other and a pipe row connecting the headers. Both the headers and the pipe row are filled with a cooling medium. The pipe row consists of two rows of heat exchange tubes distributed at the top and bottom. The overlap of the orthographic projection of the two rows of heat exchange tubes on the horizontal plane is ≥0 and less than 100%. The purpose is to realize the gravity flow of solid particles without external force, thereby achieving the effect of enhanced heat exchange. In addition, Chinese patent CN113882825A discloses a solid particle cooling device for coal grading and quality utilization. The cooling device consists of a shell and upper and lower end caps at both ends. The upper end cap has a solid particle inlet, and the lower end cap has a solid particle outlet. The shell is equipped with a spiral heat exchange tube that connects to the cooling medium. When the device is running, the solid particles spirally descend outside the heat exchange tube, and the cooling medium spirally rises inside the heat exchange tube. This is beneficial for the solid particles to mix radially along the shell outside the heat exchange tube, and also for the cooling medium to mix radially inside the heat exchange tube to form turbulence. This can improve the heat transfer coefficient and solve the problem of uneven temperature caused by poor cooling effect of solid particles far from the heat transfer surface.

[0005] It is evident that current cooling devices generally employ an internal heat exchange tube design. While this can be used to cool silicon particles, frequent friction between the silicon particles and the tubes easily leads to damage and contamination of the silicon particles. Furthermore, the impact of the silicon particles increases the risk of leakage from the tubes. Therefore, it is necessary to develop a highly efficient cooling device suitable for silicon particle cooling. Utility Model Content

[0006] The purpose of this invention is to provide a multi-stage silicon particle cooling device. This device uses a cylindrical heat exchange cylinder with jacketed cooling and a heat exchange tank with air cooling to cool silicon particles in two stages. In order to improve the cooling effect, a cylindrical heat exchange cylinder with an annular structure is used to achieve jacketed cooling with inner and outer rings. At the same time, an umbrella-shaped distributor and an optimized structure with a slope are used to ensure that silicon particles are evenly distributed in the annular cylindrical heat exchange cylinder and to reduce impact, so as to avoid damage and contamination to silicon particles.

[0007] This utility model is achieved through the following technical solution: a multi-stage silicon particle cooling device, comprising an umbrella-shaped distributor, a cylindrical heat exchange cylinder, and a heat exchange tank connected sequentially from top to bottom. The top of the umbrella-shaped distributor is provided with a silicon particle inlet, the inside of the umbrella-shaped distributor is provided with a material flow channel, and the bottom of the umbrella-shaped distributor is provided with an annular outlet. The cylindrical heat exchanger consists of an outer cylinder and an inner cylinder arranged concentrically, with an annular jacket formed between the outer cylinder and the inner cylinder. An inner heat exchange jacket is provided along the inner wall of the inner cylinder, and an outer heat exchange jacket is provided along the outer wall of the outer cylinder. The annular outlet is connected to the top of the annular jacket, and the bottom of the annular jacket is connected to the top of the heat exchanger tank through a pipeline. The heat exchange tank is provided with a heat exchange jacket on its outer wall, a gas purging port and a silicon particle outlet at its bottom, and a gas outlet at its upper part.

[0008] The width of the material flow channel is 15-20cm.

[0009] The top of the annular interlayer is sealed, and the bottom of the umbrella-shaped distributor is inserted into the top of the annular interlayer.

[0010] The ratio of the inner diameter of the outer cylinder to the inner cylinder is 10:1 to 5:1.

[0011] Two discharge ports are symmetrically arranged at the bottom of the annular interlayer. The discharge ports are connected to the top of the heat exchange tank through pipelines, and control valves are installed on the pipelines.

[0012] At least two gas purging ports are provided and are evenly distributed along the bottom of the heat exchange tank.

[0013] The material flow channel, the annular jacket, and the inner wall of the heat exchange tank are all provided with a silicon carbide lining or a silicon carbide coating.

[0014] The umbrella-shaped distributor, the inner heat exchange jacket, the outer heat exchange jacket, and the exterior of the heat exchange jacket are all provided with a heat insulation layer.

[0015] The umbrella-shaped distributor, the inner heat exchange jacket, the outer heat exchange jacket, and the exterior of the heat exchange jacket are all provided with a heat insulation layer.

[0016] Compared with the prior art, this utility model has the following advantages and beneficial effects: (1) This utility model adopts an umbrella-shaped distributor to achieve two main objectives: first, to ensure that silicon particles are evenly distributed in the annular interlayer of the cylindrical heat exchanger, thereby providing a guarantee for subsequent efficient cooling; second, to reduce the impact between silicon particles and equipment through its slope design. In addition, heat insulation cotton is installed on the outside of the umbrella-shaped distributor. Its function is, on the one hand, to prevent personnel from being burned by heat dissipation from high-temperature silicon particles and to ensure operational safety; on the other hand, to reduce the heat loss of silicon particles during the distribution process and to ensure that the silicon particles entering the heat exchanger subsequently retain sufficient heat to facilitate effective heat recovery.

[0017] (2) This utility model adopts a combination of a cylindrical heat exchange cylinder and a heat exchange tank to perform two-stage cooling of silicon particles. First, the silicon particles are evenly distributed in the annular jacket of the cylindrical heat exchange cylinder. The heat exchange cylinder has jackets on both the inner and outer sides of the annular jacket, which can simultaneously perform double-sided heat exchange on the silicon particles, achieving efficient cooling. This structure avoids the need to install heat exchange tube bundles inside the equipment and overcomes the limitation of traditional single-sided jackets that can only cool the outer silicon particles. Subsequently, the silicon particles enter the heat exchange tank and are further cooled by the jacket cooling and internal gas purging. After two-stage cooling, the temperature of the silicon particles can be reduced to 40-45℃. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of this utility model.

[0019] Figure 2 This is a top view of the cylindrical heat exchanger of this utility model.

[0020] Figure 3 This is a top view of the heat exchange tank of this utility model.

[0021] Wherein, 1—umbrella-shaped distributor, 11—silicon particle inlet, 12—material flow channel, 13—annular outlet, 2—cylindrical heat exchange cylinder, 21—outer cylinder, 22—inner cylinder, 23—annular jacket, 24—inner heat exchange jacket, 25—outer heat exchange jacket, 26—discharge port, 27—control valve, 3—heat exchange tank, 31—heat exchange jacket, 32—gas purging port, 33—silicon particle outlet, 34—gas outlet. Detailed Implementation

[0022] 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.

[0023] Example 1: This embodiment relates to a multi-stage silicon particle cooling device. The device adopts a vertical layout, and its structure is as follows: Figures 1 to 3 As shown, the system comprises an umbrella-shaped distributor 1, a cylindrical heat exchange cylinder 2, and a heat exchange tank 3, which are connected and fixedly linked from top to bottom. Through the coordinated design of the umbrella-shaped distributor 1, the cylindrical heat exchange cylinder 2, and the heat exchange tank 3, a highly efficient, stable, and safe multi-stage silicon particle cooling system can be constructed. The system first utilizes the umbrella-shaped distributor 1 with its insulation and slope design to achieve uniform silicon particle distribution, reduce mechanical impact, and effectively prevent heat loss and the risk of burns. Subsequently, a double-jacketed system is used to efficiently exchange heat on both sides of the silicon particles in the annular jacket 23 of the cylindrical heat exchange cylinder 2, completely avoiding the limitations of traditional internal tube bundles or single-sided cooling. Finally, secondary cooling is completed in the heat exchange tank 3 through jacketing and gas purging, stabilizing the silicon particle temperature to 40–45°C. The entire device not only effectively improves the cooling efficiency of silicon particles and ensures heat recovery potential, but also achieves significant results in reducing silicon particle breakage, preventing contamination, and ensuring operational safety.

[0024] Furthermore, the specific structure of this embodiment can be summarized as follows: The umbrella-shaped distributor 1 has a silicon particle inlet 11 at its top center for receiving high-temperature silicon particles (500-650℃). Inside, it has a conical or inclined material flow channel 12, the width (inner diameter) of which is designed to be 15-20 cm to ensure smooth and uniform flow of the silicon particles. The bottom opening of the umbrella-shaped distributor 1 is an annular outlet 13. For heat preservation and safety purposes, an insulation layer is wrapped around the outside of the umbrella-shaped distributor 1. Figure 1 (not shown in the image), such as thermal insulation cotton.

[0025] The cylindrical heat exchanger 2 is composed of an inner cylinder 22 and an outer cylinder 21 arranged concentrically, with an annular sandwich 23 formed between the inner cylinder 22 and the outer cylinder 21. For example... Figure 1 As shown, the bottom of the umbrella-shaped distributor 1 is inserted into and fixed at the top opening of the annular interlayer 23, so that the annular outlet 13 is directly connected to the top of the annular interlayer 23. Silicon particles can then fall vertically and evenly into the annular interlayer 23, avoiding contact with the cylinder wall and thus preventing friction. Understandably, the annular outlet 13 of the umbrella-shaped distributor 1 causes the silicon particles to fall into the annular interlayer 23 in a continuous, ring-shaped flow similar to an "annular water curtain." This flow pattern increases the heat dissipation surface area of ​​the silicon particles, ensuring their uniform distribution within the annular interlayer 23, thereby effectively improving the initial heat exchange efficiency.

[0026] like Figure 2 As shown, to achieve efficient heat exchange in the cylindrical heat exchanger 2, an inner heat exchange jacket 24 is provided along the inner wall of the inner cylinder 22, and an outer heat exchange jacket 25 is provided along the outer wall of the outer cylinder 21. The inner heat exchange jacket 24 and the outer heat exchange jacket 25 can be independently or in parallel supplied with a cooling medium (such as cooling water), thereby providing synchronous jacket cooling on both the inner and outer sides for silicon particles falling in the annular jacket 23. This structural design replaces the traditional design of setting heat exchange tube bundles inside the equipment, eliminating the risk of friction and impact between silicon particles and tube bundles.

[0027] Preferably, the inner diameter ratio of the outer cylinder 21 to the inner cylinder 22 is controlled between 10:1 and 5:1 to optimize the cooling channel cross-section. Two symmetrical discharge ports 26 are provided at the bottom of the annular jacket 23. Each discharge port 26 is connected to the top of the lower-level heat exchange tank 3 via a pipeline, and a control valve 27 is installed on each pipeline to adjust the discharge speed according to the silicon particle cooling temperature or the silicon material height. Similarly, insulation layers are also provided on the exterior of the inner heat exchange jacket 24 and the outer heat exchange jacket 25.

[0028] For the heat exchange tank 3, a heat exchange jacket 31 is provided on its outer wall. In addition to a silicon particle outlet 33, at least two gas purging ports 32 are also provided at its bottom. The gas purging ports 32 can be used... Figure 1 The curved tube shown purges gas into the tank from the side, preventing silicon particles from entering the gas tube through the gas purging port 32 and causing blockage. Figure 3As shown, gas purge ports 32 are evenly distributed along the circumference of the tank bottom for introducing cooling gas (such as hydrogen or nitrogen) to achieve through-cooling of the silicon particles. A gas outlet 34 is located at the top of the heat exchange tank 3 for discharging hot gas. Specifically, the silicon particles flowing from the cylindrical heat exchange cylinder 2 enter the heat exchange tank 3 via pipelines and continue to be cooled by the partition walls of the heat exchange jacket 31 and directly by the airflow from the gas purge ports 32, completing a two-stage cooling process. After these two stages of cooling, the silicon particle temperature can be effectively reduced to the target temperature of 40–45°C.

[0029] In a specific implementation example, the umbrella-shaped distributor 1 is insulated with 90mm thick insulation cotton. The cylindrical heat exchanger 2 is insulated with 60mm thick insulation cotton on both the inner heat exchange jacket 24 and the outer heat exchange jacket 25. The outer cylinder 21 has an outer diameter of 2000mm, the inner cylinder 22 has an outer diameter of 1745mm, and a height of 5000mm. From the outside to the inside of the outer cylinder 21, the layers are: 10mm carbon steel plate, 30mm jacket water layer, 15mm composite material, 200mm material layer, 15mm composite material, 30mm jacket water layer, and 10mm... The structure consists of a carbon steel plate, a 15mm composite material layer, a 200mm stacking layer, and another 15mm composite material layer forming an annular jacket 23. The 15mm composite material (such as a composite plate of carbon steel and stainless steel) corresponds to the side walls of the outer cylinder 21 and inner cylinder 22 of the annular jacket 23, respectively. A 10mm carbon steel plate and a 30mm jacket water layer correspond to the inner heat exchange jacket 24 and outer heat exchange jacket 25 of the annular jacket 23, respectively, ultimately forming a hollow column with a diameter of 1690mm inside the cylindrical heat exchange cylinder 2. Hot water at 130–135℃ is introduced into the jacket water layer, and after heat exchange, hot water at 150–155℃ is output. The hot water is then introduced into a flash tank for flash evaporation, producing approximately 2 kg of steam.

[0030] To further enhance the durability of the equipment and prevent material contamination, a silicon carbide lining or coating is provided on all surfaces of the internal structures that come into contact with silicon particles, namely the inner wall of the material flow channel 12 of the umbrella-shaped distributor 1, the inner wall of the annular jacket 23 of the cylindrical heat exchanger 2, and the inner wall of the heat exchange tank 3. This lining or coating has extremely high wear resistance and stability. For example, if a silicon carbide lining is used, its thickness can be set to 5 cm; if a silicon carbide coating is used, its thickness can be set to 2–5 mm.

[0031] The cooling process in this embodiment is as follows: High-temperature silicon particles enter the umbrella-shaped distributor 1 through the silicon particle inlet 11, are evenly dispersed along its material flow channel 12, and then enter the annular jacket 23 of the cylindrical heat exchange cylinder 2 through the annular outlet 13. Here, the silicon particles fall under the influence of gravity (flow velocity of about 1-3 m / s) and remain in the annular jacket 23 (for about 4-8 hours), receiving efficient cooling from both the inner heat exchange jacket 24 and the outer heat exchange jacket 25. After the first stage of cooling, the silicon particle temperature is cooled to 150-200°C, and it enters the heat exchange tank 3 through the bottom outlet 26 and control valve 27 (the silicon material level is determined by the temperature, and the control valve 27 is opened according to the silicon material level to discharge the material; usually, the silicon material level is controlled at 70-80%). In the heat exchange tank 3, the silicon particles are further cooled by the heat exchange jacket 31 and directly cooled by the cooling gas (such as room temperature hydrogen) blown in from the gas purging port 32, completing the second stage of cooling. Finally, the silicon particles cooled to 40-45°C are discharged from the silicon particle outlet 33 at the bottom of the heat exchange tank 3, completing the entire cooling process.

[0032] 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 multi-stage silicon particle cooling device, characterized in that: It includes an umbrella-shaped distributor (1), a cylindrical heat exchange cylinder (2), and a heat exchange tank (3) connected from top to bottom. The top of the umbrella-shaped distributor (1) is provided with a silicon particle inlet (11), the inside of the umbrella-shaped distributor (1) is provided with a material flow channel (12), and the bottom of the umbrella-shaped distributor (1) is provided with an annular outlet (13). The cylindrical heat exchanger (2) is composed of an outer cylinder (21) and an inner cylinder (22) arranged concentrically. An annular jacket (23) is formed between the outer cylinder (21) and the inner cylinder (22). An inner heat exchange jacket (24) is provided along the inner wall of the inner cylinder (22), and an outer heat exchange jacket (25) is provided along the outer wall of the outer cylinder (21). An annular outlet (13) is connected to the top of the annular jacket (23), and the bottom of the annular jacket (23) is connected to the top of the heat exchange tank (3) through a pipeline. The heat exchange tank (3) has a heat exchange jacket (31) on its outer wall, a gas purging port (32) and a silicon particle outlet (33) at its bottom, and a gas outlet (34) at its upper part.

2. The multi-stage silicon particle cooling device according to claim 1, characterized in that: The width of the material flow channel (12) is 15-20cm.

3. The multi-stage silicon particle cooling device according to claim 1, characterized in that: The top of the annular interlayer (23) is sealed, and the bottom of the umbrella-shaped distributor (1) is inserted into the top of the annular interlayer (23).

4. The multi-stage silicon particle cooling device according to claim 1, characterized in that: The ratio of the inner diameter of the outer cylinder (21) to the inner cylinder (22) is 10:1 to 5:

1.

5. The multi-stage silicon particle cooling device according to claim 1, characterized in that: The bottom of the annular interlayer (23) is symmetrically provided with two discharge ports (26). The discharge ports (26) are connected to the top of the heat exchange tank (3) through pipelines, and control valves (27) are provided on the pipelines.

6. The multi-stage silicon particle cooling device according to claim 1, characterized in that: At least two gas purge ports (32) are provided and are evenly distributed along the bottom of the heat exchange tank (3).

7. The multi-stage silicon particle cooling device according to claim 1, characterized in that: The inner walls of the material flow channel (12), the annular jacket (23) and the heat exchange tank (3) are all provided with a silicon carbide lining or a silicon carbide coating.

8. The multi-stage silicon particle cooling device according to claim 1, characterized in that: The umbrella-shaped distributor (1), the inner heat exchange jacket (24), the outer heat exchange jacket (25), and the exterior of the heat exchange jacket are all provided with a heat insulation layer.

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