A heat exchange device for polycrystalline silicon cold hydrogenation production
By adopting a wound tube heat exchanger and an external tube sheet design, the problems of uneven local heating and stress corrosion in heat exchangers during polycrystalline silicon production were solved, extending service life and reducing costs.
Patent Information
- Application Number
- CN202521766031.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-19
- Publication Date
- 2026-08-25
- Estimated Expiration
- 2035-08-19
AI Technical Summary
In current polysilicon production, two-stage shell-and-tube heat exchangers suffer from uneven heating and excessive temperature differences under high temperature and high pressure conditions, leading to material stress concentration, heat exchange tube breakage and stress corrosion, short service life, and high manufacturing costs.
The spiral-wound heat exchanger replaces the shell-and-tube heat exchanger. The spiral-wound heat exchange tube structure and external tube sheet design, combined with heat exchanger configurations of different areas, use S31603 and S31608 stainless steel materials to avoid uneven expansion force and stress corrosion.
It effectively avoids heat exchange tube breakage and stress corrosion, extends service life, and reduces failure rate and manufacturing cost.
Smart Images
Figure CN224681324U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of heat exchanger technology, specifically to a heat exchange device for the cold hydrogenation production of polycrystalline silicon. Background Technology
[0002] Currently, in the polysilicon production field, the gas phase outlet of the cold hydrogenation reactor uses a two-stage heat exchanger for cascaded cooling. The two-stage heat exchangers are arranged in series, and the material medium is gas phase to gas phase heat exchange. The material is at high temperature (maximum ≥550℃), high pressure (operating pressure up to 2.6MPaG), and contains hydrogen, silicon powder, etc., so its operating conditions are quite harsh.
[0003] In actual use under the above operating conditions, the existing two-stage heat exchanger has the following problems:
[0004] 1. Both stages (first and second stage) of heat exchangers are shell and tube heat exchangers. During heating and cooling, uneven heating and excessive temperature difference may occur in the inner and outer rings of the heat exchange tubes. This leads to stress concentration in the material and uneven expansion force of the inner and outer rings of the heat exchange tubes. Consequently, some heat exchange tubes may break, resulting in leakage and cross-contamination of materials in the tube side and shell side, thus increasing energy consumption.
[0005] 2. The tube sheets at both ends of the heat exchange tube are inside the cylinder, creating a displacement dead zone. The inside of the heat exchanger cannot be completely dried, leaving water molecules. Chlorosilane (material) reacts with water molecules to generate hydrogen chloride, which then ionizes into chloride ions, causing stress corrosion of the material.
[0006] 3. The heat exchange areas of the primary and secondary heat exchangers are the same. The outlet temperature of the tube side of the secondary heat exchanger is lower than the freezing point of chloride, causing chloride to precipitate. This leads to stress corrosion in the heat exchanger made of austenitic stainless steel S31668. If 800H, which is resistant to chloride ion corrosion, is used instead of S31668 to make the heat exchanger, the cost will be 5 times that of the latter, resulting in higher manufacturing costs.
[0007] The combined effect of the above factors results in a short service life for two-stage heat exchangers, with some failing after only 6 months of use. Utility Model Content
[0008] To address the shortcomings of existing technologies, this utility model provides a heat exchange device for polycrystalline silicon cold hydrogenation production, thereby solving the problems of high failure rate and short service life of existing two-stage heat exchangers.
[0009] To achieve the above objectives, the present invention provides the following technical solution:
[0010] A heat exchange device for the cold hydrogenation production of polycrystalline silicon includes:
[0011] The primary heat exchanger and the secondary heat exchanger are arranged in series;
[0012] Both the primary and secondary heat exchangers are wound-tube heat exchangers, with each heat exchange tube changing from a spiral tube to a straight tube at both ends. The spiral tube and the straight tube are connected by an arc, which is bent at a preset radius.
[0013] In one embodiment disclosed in this application, the tube-side inlet of the primary heat exchanger is connected to the gas phase outlet of the cold hydrogenation reactor, the tube-side outlet is connected to the tube-side inlet of the secondary heat exchanger, and the tube-side outlet of the secondary heat exchanger is connected to downstream equipment.
[0014] The shell-side inlet of the secondary heat exchanger is connected to the medium source to introduce the heat exchange medium, and the shell-side outlet is connected to the shell-side inlet of the primary heat exchanger. The shell-side outlet of the primary heat exchanger is connected to the medium source to draw out the heat exchange medium for circulation.
[0015] In one embodiment disclosed in this application, the preset radius is ≥300mm.
[0016] In one embodiment disclosed in this application, the primary heat exchanger and the secondary heat exchanger have the same structure, both including a shell and a pair of tube sheets;
[0017] The tube sheets are fixed to the end caps at both ends of the cylinder in a one-to-one manner.
[0018] In one embodiment disclosed in this application, the primary heat exchanger and the secondary heat exchanger further include shell-side vent pipes;
[0019] The shell-side vent pipe is inclinedly disposed on the end cap of the cylinder near the tube-side inlet.
[0020] In one embodiment disclosed in this application, the heat exchange area of the primary heat exchanger is relatively large;
[0021] The heat exchange area of the secondary heat exchanger is relatively small.
[0022] In one embodiment disclosed in this application, the heat exchange area of the primary heat exchanger is 800-900 m²;
[0023] The heat exchange area of the secondary heat exchanger is 300-400 m².
[0024] In one embodiment disclosed in this application, the tube side material of the primary heat exchanger and the secondary heat exchanger is S31603;
[0025] The shell-side material of the primary and secondary heat exchangers is S31608.
[0026] Compared with the prior art, the beneficial effects of this utility model are:
[0027] 1. The original shell and tube heat exchanger is replaced with a spiral wound heat exchanger. The tube bundle is spiral wound, which can structurally offset the uneven expansion force caused by uneven local heating and large temperature difference of the heat exchange tube. This avoids the situation of material leakage and cross-contamination caused by heat exchange tube breakage, saves energy, reduces heat exchanger operation failures, and extends the service life of the heat exchanger.
[0028] 2. By placing the tube sheet externally, there are no more displacement dead zones inside the shell, thus ensuring that the inside of the heat exchanger can be thoroughly dried without residual water molecules, thereby avoiding stress corrosion of the material.
[0029] 3. Increase the heat exchange area of the primary heat exchanger to quickly reduce the temperature of the material from the gas phase outlet of the cold hydrogenation reactor, and reduce the heat exchange area of the secondary heat exchanger to prevent the temperature at the tube side outlet of the secondary heat exchanger from falling below the chloride precipitation temperature, thereby further avoiding stress corrosion of the material.
[0030] 4. Both S31603 and S31608 are conventional austenitic stainless steels. The coiled tube heat exchanger made of these materials can not only offset the uneven expansion force of the heat exchange tubes, but also eliminate stress corrosion. At the same time, the cost is about 2 / 3 lower than that of the heat exchanger made of 800H, which greatly reduces the manufacturing cost. Attached Figure Description
[0031] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0032] Figure 1 This is a schematic diagram of the structure of this utility model. Detailed Implementation
[0033] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of this invention. Therefore, the drawings and description are considered exemplary in nature and not restrictive.
[0034] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.
[0035] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.
[0036] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in this utility model can be understood according to the specific circumstances.
[0037] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.
[0038] The following disclosure provides many different embodiments or examples for implementing various structures of this invention. To simplify the disclosure, specific examples of components and arrangements are described below. Of course, these are merely examples and are not intended to limit the scope of this invention.
[0039] The embodiments of this utility model will now be described in detail with reference to the accompanying drawings.
[0040] See Figure 1 As shown, this utility model provides a heat exchange device for the cold hydrogenation production of polycrystalline silicon, comprising:
[0041] The primary heat exchanger 10 and the secondary heat exchanger 20 are arranged in series;
[0042] Both the primary heat exchanger 10 and the secondary heat exchanger 20 are wound tube heat exchangers. The two ends of each heat exchange tube are changed from spiral tubes to straight tubes, and the spiral tubes and straight tubes are connected by an arc. The arc is bent according to a preset radius.
[0043] Specifically, the tube-side inlet of the first-stage heat exchanger 10 is connected to the gas-phase outlet of the cold hydrogenation reactor (not shown in the figure), and its tube-side outlet is connected to the tube-side inlet of the second-stage heat exchanger 20. The tube-side outlet of the second-stage heat exchanger 20 is connected to downstream equipment (not shown in the figure). The shell-side inlet of the second-stage heat exchanger 20 is connected to a medium source (not shown in the figure) to introduce the heat exchange medium, and its shell-side outlet is connected to the shell-side inlet of the first-stage heat exchanger 10. The shell-side outlet of the first-stage heat exchanger 10 is connected to the medium source to circulate the heat exchange medium. In this way, the first-stage heat exchanger 10 and the second-stage heat exchanger 20 are arranged in series.
[0044] The original shell-and-tube heat exchanger is replaced with a spiral-wound heat exchanger, whose tube bundle is spirally wound. Structurally, this can offset the uneven expansion force caused by uneven heating and excessive temperature difference in the heat exchange tubes, thereby avoiding the situation where the heat exchange tubes break and cause internal leakage and cross-contamination of materials. This saves energy, reduces the failure rate of the heat exchanger, and extends the service life of the heat exchanger.
[0045] In this embodiment, the preset radius is ≥300mm. This avoids the silicon powder in the material from causing wear on the heat exchange tube during the spiral motion, effectively extending the service life of the heat exchange tube.
[0046] The primary heat exchanger 10 and the secondary heat exchanger 20 have the same structure, both including a shell 11 and a pair of tube sheets 12. The pair of tube sheets 12 are fixed to the end caps at both ends of the shell 11 in a one-to-one manner. In this way, by placing the tube sheets externally, there are no displacement dead zones inside the shell, thereby ensuring that the inside of the heat exchanger can be thoroughly dried without residual water molecules, thus avoiding stress corrosion of the material.
[0047] The primary heat exchanger 10 and the secondary heat exchanger 20 also include a shell-side vent pipe 13, which is inclinedly disposed on the end cap of the shell body 11 near the tube-side inlet.
[0048] The primary heat exchanger 10 has a larger heat exchange area, while the secondary heat exchanger 20 has a smaller heat exchange area. Specifically, the heat exchange area of the primary heat exchanger 10 is 800–900 m², and the heat exchange area of the secondary heat exchanger 20 is 300–400 m². Based on the existing usage of two-stage heat exchangers, increasing the heat exchange area of the primary heat exchanger 10 rapidly reduces the temperature of the material from the gas phase outlet of the cold hydrogenation reactor, while reducing the heat exchange area of the secondary heat exchanger 20 prevents the outlet temperature of the tube side of the secondary heat exchanger 20 from falling below the chloride precipitation temperature, further avoiding stress corrosion of the material.
[0049] In this embodiment, the tube side (e.g., heat exchange tubes) of the primary heat exchanger 10 and the secondary heat exchanger 20 are made of S31603, and the shell side (e.g., shell 11) is made of S31608. Both S31603 and S31608 are conventional austenitic stainless steels. The wound-tube heat exchanger made of these materials can not only offset the uneven expansion force of the heat exchange tubes, but also eliminate stress corrosion. At the same time, the cost is reduced by about 2 / 3 compared with the heat exchanger made of 800H, which greatly reduces the manufacturing cost.
[0050] The above embodiments are merely preferred embodiments of this utility model and are not intended to limit the technical solutions of this utility model. Any technical solution that can be implemented based on the above embodiments without creative effort should be considered to fall within the scope of protection of this utility model patent.
Claims
1. A heat exchange device for the cold hydrogenation production of polycrystalline silicon, characterized in that, include: The primary heat exchanger and the secondary heat exchanger are arranged in series; Both the primary and secondary heat exchangers are wound-tube heat exchangers, with each heat exchange tube changing from a spiral tube to a straight tube at both ends. The spiral tube and the straight tube are connected by an arc, which is bent at a preset radius.
2. The heat exchange device for polycrystalline silicon cold hydrogenation production according to claim 1, characterized in that: The tube-side inlet of the first-stage heat exchanger is connected to the gas phase outlet of the cold hydrogenation reactor, and the tube-side outlet is connected to the tube-side inlet of the second-stage heat exchanger. The tube-side outlet of the second-stage heat exchanger is connected to downstream equipment. The shell-side inlet of the secondary heat exchanger is connected to the medium source to introduce the heat exchange medium, and the shell-side outlet is connected to the shell-side inlet of the primary heat exchanger. The shell-side outlet of the primary heat exchanger is connected to the medium source to draw out the heat exchange medium for circulation.
3. The heat exchange device for polycrystalline silicon cold hydrogenation production according to claim 1, characterized in that, The preset radius is ≥300mm.
4. The heat exchange device for polycrystalline silicon cold hydrogenation production according to any one of claims 1 to 3, characterized in that: The primary heat exchanger and the secondary heat exchanger have the same structure, both including a shell and a pair of tube sheets; The tube sheets are fixed to the end caps at both ends of the cylinder in a one-to-one manner.
5. The heat exchange device for polycrystalline silicon cold hydrogenation production according to claim 4, characterized in that: The primary heat exchanger and the secondary heat exchanger also include shell-side vent pipes; The shell-side vent pipe is inclinedly disposed on the end cap of the cylinder near the tube-side inlet.
6. The heat exchange device for polycrystalline silicon cold hydrogenation production according to claim 1 or 5, characterized in that: The heat exchange area of the primary heat exchanger is relatively large. The heat exchange area of the secondary heat exchanger is relatively small.
7. The heat exchange device for polycrystalline silicon cold hydrogenation production according to claim 6, characterized in that: The heat exchange area of the primary heat exchanger is 800-900 m². The heat exchange area of the secondary heat exchanger is 300-400 m².
8. The heat exchange device for polycrystalline silicon cold hydrogenation production according to claim 1 or 7, characterized in that: The tube side material of the primary heat exchanger and the secondary heat exchanger is S31603. The shell-side material of the primary and secondary heat exchangers is S31608.