Tail gas cooling structure and polycrystalline silicon equipment

Abstract

The utility model provides a tail gas cooling structure and polycrystalline silicon equipment, the tail gas cooling structure comprises a jacketed pipe and a guide plate, the jacketed pipe comprises an inner pipe and an outer pipe, the outer pipe sleeves the periphery of the inner pipe, a tail gas channel is formed in the inner pipe, and a cooling cavity for accommodating a cooling medium is formed between the inner pipe and the outer pipe; the guide plate is arranged in the cooling cavity. According to the tail gas cooling structure, the flow guide plate is arranged in the cooling cavity between the inner pipe and the outer pipe, so that the cooling medium flows according to a specific path, it is ensured that the cooling medium sufficiently flows through all areas of the cooling cavity, and cooling is more uniform. And meanwhile, the guide plate is arranged, so that the contact time of the cooling medium and the inner pipe can be prolonged, the heat exchange efficiency is optimized, tail gas in the tail gas channel can be cooled more effectively, and the cooling and heat exchange performance is improved. In addition, the contact temperature of the inner pipe and the tail gas is reduced, so that the silicon junction condition of the inner pipe is reduced, and the cleaning difficulty is further reduced.

Description

Technical Field

[0001] The present application relates to the technical field of polysilicon production, and in particular to an exhaust gas cooling structure and polysilicon equipment. Background Art

[0002] Currently, polysilicon production primarily utilizes a modified Siemens process, with the polysilicon reduction furnace being a core component of this process. The reaction between the raw trichlorosilane and hydrogen produces a by-product exhaust gas mixture consisting of chlorosilane and hydrogen, which is discharged through an exhaust jacket. Due to the high exhaust temperature and inadequate cooling, chlorosilane easily forms silicon on the inner surface of the exhaust jacket.

[0003] After siliconization, it is difficult to clean, which leads to a decrease in the heat transfer performance of the jacketed tube. Firstly, it will affect the service life of the jacketed tube. Secondly, the exhaust gas temperature cannot be lowered, resulting in a high overall temperature in the exhaust gas system, affecting the process. Utility Model Content

[0004] In view of this, the purpose of this application is to propose an exhaust gas cooling structure and polysilicon equipment that improves the cooling and heat exchange effect and reduces the difficulty of cleaning.

[0005] Based on the above purpose, the present application provides an exhaust gas cooling structure, which includes: a jacketed tube, the jacketed tube including an inner tube and an outer tube, the outer tube being sleeved on the outer circumference of the inner tube, an exhaust gas channel being formed in the inner tube, and a cooling cavity for accommodating a cooling medium being formed between the inner tube and the outer tube;

[0006] A guide plate is arranged in the cooling cavity.

[0007] In a preferred embodiment, the direction in which the cooling medium is guided by the guide plate is opposite to the flow direction of the exhaust gas in the exhaust gas channel.

[0008] In a preferred embodiment, the inner tube is provided with a first inlet and a first outlet, and the first inlet and the first outlet are respectively communicated with the exhaust gas channel;

[0009] The outer tube is provided with a second inlet and a second outlet, the second inlet and the second outlet are respectively communicated with the cooling cavity;

[0010] Wherein, the first inlet and the second outlet are arranged at the same end of the jacket tube.

[0011] In a preferred embodiment, in a working state, the extension direction of the jacket tube is a vertical direction, and the first inlet and the second outlet are arranged at the top end of the jacket tube.

[0012] In a preferred embodiment, the guide plate includes a spiral structure, and the spiral structure is wound around the outer circumference of the inner tube.

[0013] In a preferred embodiment, the guide plate is connected to the inner tube, and there is a gap between the guide plate and the outer tube;

[0014] Alternatively, the guide plate is connected to the outer tube, and a gap exists between the guide plate and the inner tube.

[0015] In a preferred embodiment, the exhaust gas cooling structure includes at least two groups of guide plates, and the at least two groups of guide plates are spaced apart and arranged in the cooling cavity.

[0016] In a preferred embodiment, the exhaust gas cooling structure also includes a jacket flange, which is arranged at the end of the jacket tube, and the jacket flange includes a disc body and a raised portion protruding from the disc body toward the inside of the jacket tube, the disc body includes a connecting through hole, the raised portion includes a flange hole, the raised portion is docked with the inner tube, and the flange hole is connected to the exhaust gas channel.

[0017] In a preferred embodiment, the exhaust gas cooling structure also includes a connecting pipe, a first end of the connecting pipe is connected to the cooling chamber, and a second end of the connecting pipe is provided with a connecting flange, and a surface of the connecting flange away from the jacket tube is flush with a surface of the jacket flange away from the jacket tube.

[0018] Based on the same inventive concept, the present application also discloses a polysilicon device, which includes:

[0019] furnace body;

[0020] The exhaust gas cooling structure is connected to the furnace body.

[0021] As can be seen from the above, the exhaust gas cooling structure provided by the present application can guide the cooling medium introduced into the cooling cavity by setting a guide plate in the cooling cavity between the inner tube and the outer tube, so that the cooling medium flows along a specific path, ensuring that the cooling medium fully flows through all areas of the cooling cavity, making the cooling more uniform. At the same time, the provision of a guide plate can increase the contact time between the cooling medium and the inner tube, optimize the heat exchange efficiency, and ensure more effective cooling of the exhaust gas in the exhaust gas channel, thereby improving the cooling and heat exchange performance. In addition, by reducing the temperature at which the inner tube contacts the exhaust gas, the occurrence of siliconization in the inner tube is reduced, thereby reducing the difficulty of cleaning. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in this application or related technologies, the following briefly introduces the drawings required for use in the embodiments or related technical descriptions. Obviously, the drawings described below are merely embodiments of this application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0023] Figure 1 This is a cross-sectional schematic diagram of an exhaust gas cooling structure in one embodiment of the present application;

[0024] Figure 2 This is a cross-sectional schematic diagram of an exhaust gas cooling structure in another embodiment of the present application;

[0025] Figure 3 This is a cross-sectional schematic diagram of a jacket flange in another embodiment of the present application;

[0026] Figure 4 This is a structural diagram of a polysilicon device in another embodiment of the present application.

[0027] Reference numerals

[0028] 100. Exhaust gas cooling structure; 101. Exhaust gas channel; 102. Cooling chamber;

[0029] 1. Jacketed tube; 11. Inner tube; 111. First inlet; 112. First outlet; 12. Outer tube; 121. Second inlet; 122. Second outlet;

[0030] 2. Guide plate;

[0031] 3. Jacket flange; 31. Disc body; 311. Connecting through hole; 32. Raised portion; 321. Flange hole;

[0032] 4. Connecting pipe; 41. Connecting flange;

[0033] 5. Furnace body. DETAILED DESCRIPTION

[0034] In order to make the objectives, technical solutions and advantages of this application more clear, this application is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0035] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the embodiments of the present application should have the usual meanings understood by people with ordinary skills in the field to which this application belongs. The "first", "second" and similar words used in the embodiments of the present application do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0036] In a polysilicon reduction furnace, trichlorosilane (TCS) and hydrogen (H2) enter as feed gases, reacting under high temperature and pressure. The primary reaction is SiHCl3 + H2 = Si + 3HCl, accompanied by side reactions. The resulting tail gas is hot, making direct treatment difficult and dangerous. Instead, it is typically cooled using a tail gas cooling system.

[0037] After extensive research, the inventors discovered that the jacketed tube exhaust cooling structure of current polysilicon equipment consists of only an inner and outer tube. When cooling the exhaust gas, cooling water is passed between the inner and outer tubes, moving directly from one end of the jacketed tube to the other, resulting in suboptimal cooling and heat exchange. Furthermore, silicon begins to form on the inner tube wall at around 400°C, making it difficult to clean.

[0038] Based on this, the present application provides an exhaust gas cooling structure to solve the above technical problems, with specific reference to the following embodiments.

[0039] Reference Figure 1 、 Figure 2 As shown, one embodiment of the present application discloses an exhaust gas cooling structure 100, which includes a jacketed tube 1 and a guide plate 2. The jacketed tube 1 includes an inner tube 11 and an outer tube 12, with the outer tube 12 being sleeved around the outer circumference of the inner tube 11. An exhaust gas channel 101 is formed within the inner tube 11, and a cooling cavity 102 for accommodating a cooling medium is formed between the inner tube 11 and the outer tube 12. The guide plate 2 is disposed in the cooling cavity 102 to guide the flow direction of the cooling medium.

[0040] Specifically, an annular space, i.e., a cooling cavity 102, is formed between the nested inner and outer tubes 11, 12. A cooling medium is introduced into the cooling cavity 102 and flows along the guide plate 2 in the cooling cavity 102 to cool the inner tube 11 and the exhaust passage 101.

[0041] In the exhaust gas cooling structure 100 provided in the present application, by providing a guide plate 2 in the cooling cavity 102 between the inner tube 11 and the outer tube 12, the cooling medium introduced into the cooling cavity 102 can be guided. The guide plate 2 can guide the cooling medium to flow along a specific path, ensuring that the cooling medium fully flows through each area of ​​the cooling cavity 102, making the cooling more uniform. At the same time, providing the guide plate 2 can increase the contact time between the cooling medium and the inner tube 11, optimize the heat exchange efficiency, and ensure more effective cooling of the exhaust gas in the exhaust channel 101, thereby improving the cooling and heat exchange performance. In addition, by reducing the temperature at which the inner tube contacts the exhaust gas, the occurrence of siliconization in the inner tube is reduced, thereby reducing the difficulty of cleaning.

[0042] In the present application, the cooling medium may be a cooling liquid, such as cooling water, or a cooling gas.

[0043] Reference Figure 2 As shown, in one embodiment, the guide plate 2 guides the flow direction of the cooling medium in the cooling cavity 102 to be opposite to the flow direction of the exhaust gas in the exhaust gas channel 101 .

[0044] Among them, the direction of flow of the cooling medium in the cooling chamber 102 is guided by the guide plate 2 so that it is opposite to the flow direction of the exhaust gas in the exhaust channel 101. Since there is always a large temperature difference between the cooling medium and the exhaust gas in the entire jacketed tube 1, this countercurrent heat exchange method can achieve efficient heat exchange, and heat can be continuously and quickly transferred from the exhaust gas to the cooling medium. Compared with the cocurrent method, the heat exchange efficiency can be greatly improved, and the exhaust gas temperature can be more effectively reduced, which helps to meet the subsequent requirements for the exhaust gas temperature and the recycling needs of cooling water.

[0045] For example, the guide plate 2 may be vertically, obliquely, or spirally arranged in the cooling chamber 102 . In other words, the plane where the guide plate 2 is located is parallel to or at an acute angle to the central axis of the jacket tube 1 .

[0046] Please continue to refer to Figure 2 As shown, in one embodiment, the inner tube 11 is provided with a first inlet 111 and a first outlet 112, and the first inlet 111 and the first outlet 112 are respectively connected to the exhaust channel 101. The outer tube 12 is provided with a second inlet 121 and a second outlet 122, and the second inlet 121 and the second outlet 122 are respectively connected to the cooling chamber 102. The first inlet 111 and the second outlet 122 are provided at the same end of the jacket tube 1.

[0047] The first inlet 111 of the exhaust passage 101 and the second outlet 122 of the cooling chamber 102 are arranged at the same end of the jacketed tube 1, and may include an end position and a position where the outer circumferences of the inner and outer tubes are close to the end. Correspondingly, the first outlet 112 of the exhaust passage 101 and the second inlet 121 of the cooling chamber 102 can be arranged at the other end of the jacketed tube 1, and may include an end position and a position where the outer circumferences of the inner and outer tubes are close to the end, thereby achieving a flow direction of the cooling medium in the cooling chamber 102 opposite to the flow direction of the exhaust gas in the exhaust passage 101. The first inlet 111 can be an exhaust gas inlet, and the first outlet 112 can be an exhaust gas outlet. The second inlet 121 can be a water inlet, and the second outlet 122 can be a water outlet.

[0048] Reference Figure 1 、 Figure 2 As shown, in one embodiment, in the working state, the extension direction of the jacket tube 1 is the vertical direction, and the first inlet 111 and the second outlet 122 are arranged at the top end of the jacket tube 1.

[0049] The exhaust gas flows from top to bottom in the exhaust gas channel 101 within the inner tube 11. Simultaneously, in the cooling chamber 102 between the inner tube 11 and the outer tube 12, the cooling medium flows from bottom to top via the guide plate 2. First, a countercurrent heat exchange is formed, thereby achieving efficient heat transfer and improving the cooling effect of the exhaust gas. Second, the cooling medium flowing from bottom to top can fully utilize its own gravity combined with the guiding effect of the guide plate 2 to ensure uniform and stable flow within the cooling chamber 102, avoiding local overheating or uneven cooling, and ensuring the stability and effectiveness of the exhaust gas cooling process.

[0050] Continue to refer to Figure 1 、 Figure 2 As shown, in one embodiment, the guide plate 2 includes a spiral structure, which is wound around the outer circumference of the inner tube 11.

[0051] Among them, the guide plate 2 with a spiral structure can increase the flow length of the cooling medium in the jacketed tube 1, so that the cooling medium has more sufficient contact time with the inner tube exhaust, thereby improving the heat exchange efficiency. The guide plate 2 with a spiral structure can also guide the cooling medium to form a spiral upward flow path in the cooling chamber. This flow mode makes the flow velocity distribution of the cooling medium more uniform, avoiding the situation where the local flow velocity is too fast or too slow, and thus preventing the occurrence of local uneven cooling. At the same time, the spiral guide plate can cause a certain disturbance to the flow of the cooling medium, destroy its laminar state, promote the formation of turbulence, enhance the heat transfer effect, and make the exhaust gas more effectively cooled.

[0052] Continue to refer to Figure 1 、 Figure 2As shown, in one embodiment, the guide plate 2 is connected to the inner tube 11, and a gap exists between the guide plate 2 and the outer tube 12. Specifically, the guide plate 2 is fixed to the outer circumference of the inner tube 11, and a gap exists between the guide plate 2 and the inner wall of the outer tube 12.

[0053] The guide plate 2 can be installed on the outer circumference of the inner tube 11. While guiding the flow, the guide plate 2 also acts as a heat dissipation fin, directly dissipating heat and cooling the inner tube 11. The guide plate 2 does not contact the outer tube 12, and the gap between them can be controlled within one millimeter. During assembly, the guide plate 2 is first fixed to the inner tube 11, and then the outer tube 12 is placed around the outer circumference of the guide plate 2, making installation more convenient. At the same time, the presence of the gap prevents direct contact between the guide plate 2 and the inner wall of the outer tube 12, preventing structural damage caused by factors such as thermal expansion and contraction, and ensuring the stability and reliability of the entire jacketed tube 1 during long-term operation.

[0054] In another embodiment, the guide plate 2 is connected to the outer tube 12, and a gap exists between the guide plate 2 and the inner tube 11. Specifically, the guide plate 2 is fixed to the inner wall surface of the outer tube 12, and a gap exists between the guide plate 2 and the outer peripheral surface of the inner tube 11.

[0055] In one embodiment, the exhaust gas cooling structure 100 includes at least two sets of guide plates 2, spaced apart within the cooling chamber 102. First, providing multiple sets of guide plates 2 further optimizes the flow path of the cooling medium, making the flow more complex and orderly, thereby improving heat exchange efficiency. Second, multiple sets of guide plates 2 help to achieve a more uniform flow distribution of the cooling medium, reducing areas of excessively high or low flow velocity, and avoiding significant variations in local heat exchange effects due to uneven flow, thereby ensuring consistent heat exchange effects along the entire length of the inner tube 11.

[0056] Reference Figure 1 、 Figure 3 As shown, in one embodiment, the exhaust gas cooling structure 100 further includes a jacket flange 3, which is disposed at the end of the jacket tube 1. The jacket flange 3 includes a disc portion 31 and a raised portion 32. The raised portion 32 is formed by the disc portion 31 protruding into the interior of the jacket tube 1. The disc portion 31 includes a connecting through-hole 311, which axially penetrates the disc portion 31. The raised portion 32 includes a flange hole 321, which axially penetrates the raised portion 32. The raised portion 32 is connected to the inner tube 11, and the flange hole 321 is connected to the exhaust gas channel 101.

[0057] Specifically, the jacket flange 3 is sealed at the bottom end of the cooling cavity 102 in the jacket tube 1, and the second inlet 121 can be set at a position near the bottom end of the outer peripheral surface of the outer tube 12. The first outlet 112 can be set at the flange hole 321. Among them, the inner tube 11 and the outer tube 12 can be welded to the jacket flange 3, so as to realize the connection between the inner tube 11 and the outer tube 12, and the jacket flange 3 can seal the cooling cavity 102 between the inner tube 11 and the outer tube 12 to prevent leakage of the cooling medium. Among them, the jacket flange 3 is also connected to other jacket tube sections through the connecting through hole 311. The raised portion 32 in the middle of the jacket flange 3 helps to enhance the structural strength. In addition, the raised portion 32 is located at the end of the cooling cavity 102, which can change the flow state of the cooling medium to a certain extent, causing the cooling medium to form local turbulence or disturbance around the raised portion 32, thereby improving the heat exchange efficiency.

[0058] Reference Figure 1 As shown, in one embodiment, the exhaust gas cooling structure 100 further includes a connecting pipe 4, a first end of the connecting pipe 4 is connected to the cooling chamber 102, and a second end of the connecting pipe 4 is provided with a connecting flange 41, and a surface of the connecting flange 41 away from the jacket tube 1 is flush with a surface of the jacket flange 3 away from the jacket tube 1.

[0059] Specifically, the connecting pipe 4 communicates with the cooling chamber 102 via the second inlet 121, allowing the cooling medium to be introduced into the cooling chamber 102 through the connecting pipe 4. For example, the cooling medium may be cooling water, and the connecting pipe 4 may serve as a water inlet pipe. The connecting pipe 4 may be configured as an L-shaped structure, with the connecting flange 41 flush with the bottom surface of the jacket flange 3, to facilitate connection to other jacketed pipe structures.

[0060] In this application, for example, in order to ensure the heat exchange effect, the inner tube 11 and the guide plate 2 can be made of materials with higher thermal conductivity, respectively, and the specific selection can be made according to actual needs. For example, in terms of metal materials, copper and copper alloys can be used, which have high thermal conductivity and can transfer heat quickly, and are suitable for small systems with extremely high requirements for heat exchange efficiency; aluminum and aluminum alloys can also be used, which have high thermal conductivity, light weight, low cost, and are widely used in general industrial fields; stainless steel can also be used, although its thermal conductivity is lower than the first two, but it has good corrosion resistance and is suitable for occasions with corrosive media. Among non-metallic materials, alumina ceramics can be used, which have high thermal conductivity, high temperature resistance, corrosion resistance and good insulation, and are used in special high-temperature and strong corrosive environments; graphite materials can also be used, which have high thermal conductivity and good chemical stability, and are suitable for heat exchange in high-temperature environments.

[0061] Another embodiment of the present application discloses a polysilicon device, which includes a furnace body 5 and the exhaust gas cooling structure 100 described in the above embodiment. The exhaust gas cooling structure 100 is connected to the furnace body 5. The specific structure, mechanism, and technical effects of the exhaust gas cooling structure 100 are described in the above embodiment and will not be repeated here.

[0062] Exemplarily, the polysilicon equipment is a polysilicon production device, such as a polysilicon reduction furnace. Specifically, in the polysilicon equipment, after the exhaust gas is cooled by the exhaust gas cooling structure 100, silicon powder in the exhaust gas is prevented from being deposited on the inner wall of the inner tube in large quantities, thereby maintaining a long-lasting and efficient cooling effect of the exhaust gas cooling structure. Cooling the exhaust gas also reduces equipment requirements, extending equipment service life, and is also beneficial for exhaust gas purification, reducing environmental impact.

[0063] It should be noted that the above description is limited to some embodiments of the present application. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims can be performed in a different order than that described in the above embodiments and still achieve the desired results. Furthermore, the processes depicted in the accompanying drawings do not necessarily require the specific order or sequential order shown to achieve the desired results.

[0064] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present application (including the claims) is limited to these examples. Within the scope of the present application, the technical features of the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of different aspects of the above embodiments of the present application, which are not provided in detail for the sake of simplicity.

[0065] The embodiments of the present application are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present application should be included in the scope of protection of this application.

Claims

1. An exhaust gas cooling structure, characterized in that: include: A jacketed tube, the jacketed tube comprising an inner tube and an outer tube, the outer tube being sleeved on the outer circumference of the inner tube, an exhaust gas channel being formed in the inner tube, and a cooling cavity for accommodating a cooling medium being formed between the inner tube and the outer tube; A guide plate, the guide plate is arranged in the cooling cavity, The inner tube is provided with a first inlet and a first outlet, wherein the first inlet and the first outlet are respectively communicated with the exhaust gas channel; The outer tube is provided with a second inlet and a second outlet, the second inlet and the second outlet are respectively communicated with the cooling cavity; The first inlet and the second outlet are arranged at the same end of the jacket tube, and the direction in which the cooling medium is guided by the guide plate is opposite to the flow direction of the exhaust gas in the exhaust gas channel.

2. The exhaust gas cooling structure according to claim 1, characterized in that: In a working state, the extension direction of the jacket tube is a vertical direction, and the first inlet and the second outlet are arranged at the top end of the jacket tube.

3. The exhaust gas cooling structure according to claim 1, characterized in that: The guide plate includes a spiral structure, and the spiral structure is wound around the outer circumference of the inner tube.

4. The exhaust gas cooling structure according to claim 1, characterized in that: The guide plate is connected to the inner tube, and there is a gap between the guide plate and the outer tube; Alternatively, the guide plate is connected to the outer tube, and a gap exists between the guide plate and the inner tube.

5. The exhaust gas cooling structure according to claim 1, characterized in that: The exhaust gas cooling structure includes at least two groups of guide plates, and the at least two groups of guide plates are arranged in the cooling cavity at intervals.

6. The exhaust gas cooling structure according to claim 1, characterized in that: The exhaust gas cooling structure also includes a jacket flange, which is arranged at the end of the jacket tube. The jacket flange includes a disc body and a raised portion protruding from the disc body toward the inside of the jacket tube. The disc body includes a connecting through hole, and the raised portion includes a flange hole. The raised portion is docked with the inner tube, and the flange hole is connected to the exhaust gas channel.

7. The exhaust gas cooling structure according to claim 6, characterized in that: The exhaust gas cooling structure also includes a connecting pipe, a first end of which is connected to the cooling cavity, and a second end of which is provided with a connecting flange, and a surface of the connecting flange away from the jacket tube is flush with a surface of the jacket flange away from the jacket tube.

8. A polysilicon device, characterized in that: include: furnace body; The exhaust gas cooling structure according to any one of claims 1 to 7, wherein the exhaust gas cooling structure is connected to the furnace body.

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