A two-pass heat exchanger

Abstract

This utility model belongs to the field of heat exchangers, specifically relating to a two-pass heat exchanger, including a double-shell, tube sheet, first end cap, and heat exchange tubes; a second tube-pass channel is provided inside the shell wall of the double-shell, and tube sheets are provided at both axial ends of the double-shell; the heat exchange tubes are located inside the double-shell and penetrate both tube sheets; the first end cap is located on the tube sheet side and connects the inlet / outlet of the heat exchange tube and the second tube-pass channel; the second tube-pass channel connects to the inlet / outlet of tube-side material; it also includes a shell-side material inlet and a shell-side material outlet connected to the double-shell. The two-pass heat exchanger provided by this utility model, by setting a second tube-pass channel to form a two-pass structure, can improve the heat exchange effect by increasing the heat exchange area of ​​tube-side material and shell-side material, and can also be used as a cooling channel or insulation channel for the double-shell, improving the adaptability of the two-pass heat exchanger in different application scenarios.

Description

Technical Field

[0001] This utility model belongs to the field of heat exchangers, specifically relating to a two-pass heat exchanger. Background Technology

[0002] Traditional shell-and-tube heat exchangers typically employ a single tube-side and shell-side design, with fluid exchanging heat through the tube walls. Heat exchange efficiency is limited by the surface area of ​​the tubes. Furthermore, conventional designs lack effective insulation for the outer shell surface, allowing heat to easily dissipate and reducing heat exchange efficiency. This invention proposes a novel shell-and-tube heat exchanger that incorporates a jacket structure within the shell, integrating the jacket with the tube side to expand the heat transfer surface, thereby increasing the heat exchange area and providing insulation. Utility Model Content

[0003] The technical problem to be solved by this utility model is to provide a double-pass heat exchanger that increases the heat exchange area and achieves the effect of heat preservation or cooling by setting a second tube passage in the outer shell to expand the heat transfer surface.

[0004] This utility model provides a two-pass heat exchanger, including a double-layer shell, a tube sheet, a first end cap, and at least one heat exchange tube;

[0005] The double-shell shell has a second tube pass channel arranged in the axial direction inside the shell wall, and tube sheets are provided at both ends of the double-shell shell in the axial direction.

[0006] The heat exchange tubes are located inside the double-shell structure and penetrate both tube sheets;

[0007] The first end cap is disposed on one of the tube sheet sides, and the first end cap is connected to the inlet / outlet of the heat exchange tube and the second tube side channel;

[0008] The second pipe passage connects to the pipe material inlet / outlet;

[0009] This two-pass heat exchanger also includes a shell-side material inlet and a shell-side material outlet that are connected to the double-layer shell.

[0010] Furthermore, the material inlet / outlet of the tube is located at the end of the second tube passage opposite to the first head.

[0011] Furthermore, multiple heat exchange tubes are arranged at intervals between each other;

[0012] The inlet and outlet of multiple heat exchange tubes are connected to the second tube pass through the first end cap.

[0013] Furthermore, this double-pass heat exchanger also includes a second end cap, which is provided with a tube-side material inlet / outlet;

[0014] The second end cap is located on the other tube sheet side, and the second end cap connects the tube-side material inlet / outlet and the inlet / outlet of multiple heat exchange tubes.

[0015] Furthermore, the second head is a double-layer head, and a third tube passage is provided on the inner wall of the double-layer head;

[0016] The third pipe passage is connected to the second pipe passage at the end opposite to the first end cap, and the pipe passage material inlet / outlet is set on the third pipe passage and is connected to the second pipe passage through the third pipe passage.

[0017] Furthermore, the tube sheet is provided with mounting holes for installing heat exchange tubes and tube sheet guide holes that connect the first end cap, the second end cap, and the second tube pass channel.

[0018] Furthermore, the double-layer shell includes an outer shell and an inner shell coaxially disposed within the outer shell, with the inner wall of the outer shell and the outer wall of the inner shell enclosing each other to form a second tube passage;

[0019] The double-layer head includes a second outer head and a second inner head. The inner wall of the second outer head and the outer wall of the second inner head enclose each other to form a third pipe passage.

[0020] Furthermore, both ends of the outer shell and the inner shell are provided with shell connecting flanges, and the shell connecting flanges are provided with shell flange guide holes, which are connected to the tube sheet guide holes;

[0021] The second outer head and the second inner head are provided with a second head connecting flange at their ends. The second head connecting flange, the tube sheet and the shell connecting flange are fastened together by fasteners. The second head connecting flange is provided with a head flange guide hole that connects the tube sheet guide hole and the third tube passage.

[0022] The first end cap is provided with a first end cap connecting flange, and the first end cap connecting flange, tube sheet and shell connecting flange are fastened together by fasteners; the first end cap is connected to the second tube pass through the tube sheet guide hole.

[0023] Furthermore, the shell-side material inlet and shell-side material outlet are located on both sides of the double-layer shell;

[0024] The double-layered shell contains baffles arranged alternately along the axial direction.

[0025] Furthermore, a spiral guide is provided along the axial direction in the second tube passage.

[0026] The beneficial effects of this invention are that the dual-tube heat exchanger provided by this invention can perform mutual heat exchange between shell-side material and tube-side material. The tube-side material passes through the second tube-side channel and the heat exchange tubes. When the tube-side material passes through the second tube-side channel in the double-shell structure, on the one hand, the flow area of ​​the tube-side material can be expanded, forming a multi-stage heat transfer path, allowing the tube-side material to flow through the heat exchange area of ​​the shell-side material twice, thus expanding the heat exchange area between the tube-side and shell-side materials; on the other hand, when the shell-side material is high-temperature and the tube-side material is low-temperature, if the double-shell structure needs to meet thermal protection requirements, the unexchanged low-temperature tube-side material can flow through the second tube-side channel (in this case, the tube-side material's transport path is the second one mentioned above). In this case, the second tube-side channel can act as a water-cooling clamp for the double-shell structure. The first layer prevents the high-temperature shell material from damaging the thermal protection effect of the double-layer shell, ensuring the external temperature of the double-layer shell and reducing safety hazards. If the double-layer shell needs to meet certain insulation requirements, the second tube-side channel can be used to circulate the low-temperature tube-side material that has undergone heat exchange (in this case, the tube-side material transport path is the first one mentioned above). Since the temperature of the low-temperature tube-side material rises after heat exchange, but remains lower than that of the high-temperature shell material, the second tube-side channel can act as an insulation layer for the double-layer shell, preventing excessive ineffective heat loss within the shell-side material's heat exchange chamber and ensuring the heat exchange effect between the shell-side and tube-side materials. When the shell-side material is low-temperature and the tube-side material is high-temperature, if the double-layer shell needs to be used as a cooling shell, the first tube-side material transport path is used, and the second tube-side channel circulates the cooled tube-side material. If the double-layer shell needs to be used as an insulation shell, the second tube-side material transport path is used, and the second tube-side channel circulates the high-temperature tube-side material, which can improve the insulation and heat exchange effect.

[0027] In summary, the dual-tube heat exchanger provided by this utility model forms a dual-tube structure by setting a second tube passage. It can improve the heat exchange effect by increasing the heat exchange area of ​​the tube-side material and the shell-side material. Furthermore, depending on the flow path of the tube-side material and the initial temperature difference, the second tube passage can be used as a cooling channel or a heat preservation channel for the double-shell shell, thereby improving the adaptability of the dual-tube heat exchanger in different application scenarios. Attached Figure Description

[0028] Appendix Figure 1 This is a schematic diagram of the structure of the double-pass heat exchanger in this utility model;

[0029] Appendix Figure 2 For the appendix Figure 1 Sectional view along line AA;

[0030] Appendix Figure 3 For the appendix Figure 2 Sectional view along the BB direction;

[0031] Appendix Figure 4 For the appendix Figure 3 A schematic diagram of one of the conveying paths for bottom tube material and shell material (solid arrows indicate the flow path of bottom tube material, and hollow arrows indicate the flow path of shell material).

[0032] Appendix Figure 5 For the appendix Figure 3 Enlarged view of the mating area between the lower second head and the tube sheet;

[0033] Appendix Figure 6 For the appendix Figure 3 Enlarged view of the mating area between the lower first head and the tube sheet;

[0034] Appendix Figure 7 This is a cross-sectional view of the double-layer shell in this utility model.

[0035] In the diagram, 1-material inlet / outlet; 2-inner head; 3-outer head; 4-material inlet / outlet; 5-tube sheet; 6-shell-side material outlet; 7-outer shell; 8-inner shell; 9-baffle plate; 10-spiral guide; 11-fastener; 12-first head; 13-shell-side material inlet; 14-heat exchange tube; 15-second tube-side passage; 16-third tube-side passage; 17-head flange guide hole; 18-shell flange guide hole; 19-tube sheet guide hole; 20-sealing ring; 21-shell-side material heat exchange chamber. Detailed Implementation

[0036] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0037] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in this utility model embodiment are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0038] Furthermore, in this utility model, the use of terms such as "first," "second," etc., is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this utility model, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0039] In this utility model, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection, an electrical connection, a physical connection, or a wireless communication connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal connection of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0040] Furthermore, the technical solutions of the various embodiments of this utility model can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this utility model.

[0041] As attached Figure 1 -Appendix Figure 7 As shown, this utility model provides a double-pass heat exchanger, including a double-layer shell, a tube sheet 5, a first end cap 12 and at least one heat exchange tube 14;

[0042] A second tube-side channel 15 is provided in the axial direction inside the double-shell shell wall. The second tube-side channel 15 is used for the flow of tube-side material. The double-shell shell is a hollow structure with openings at both ends. Tube sheets 5 are provided at both ends of the double-shell shell. The two tube sheets 5 block the openings at both ends of the double-shell shell. The hollow part inside the double-shell shell and the opposite side of the two tube sheets 5 enclose the shell-side material heat exchange chamber 21.

[0043] The heat exchange tube 14 is also hollow inside and open at both ends. The hollow interior forms a first tube-side channel for the flow of tube-side material. Thus, the heat exchange tube 14 and the second tube-side channel 15 form a double-tube-side structure. The heat exchange tube 14 is located inside the double-layer shell and penetrates both tube sheets 5. That is, the tube body of the heat exchange tube 14 is located inside the shell-side material heat exchange chamber 21, while the inlet and outlet of the heat exchange tube 14 are located outside the shell-side material heat exchange chamber 21.

[0044] The first end cap 12 is disposed on one side of one of the tube sheets 5, and the first end cap 12 connects the inlet / outlet of the heat exchange tube 14 and the second tube passage 15. Preferably, the first end cap 12 is a cylindrical structure with a hollow interior and an open end. The opening of the first end cap 12 blocks the tube sheet 5, and the hollow interior of the first end cap 12 connects the inlet / outlet of the heat exchange tube 14 and the second tube passage 15. The hollow interior of the first end cap 12 is used for the flow of tube passage material.

[0045] The second pipe passage 15 is connected to the pipe material inlet / outlet 4;

[0046] It also includes a shell-side material inlet 13 and a shell-side material outlet 6 connected to the double-layer shell. The shell-side material flows into the shell-side material heat exchange chamber 21 from the shell-side material inlet 13 and flows out of the shell-side material heat exchange chamber 21 from the shell-side material outlet 6.

[0047] The tubular material has two conveying paths. The first path is described in the attached diagram. Figure 4 In the first configuration, the tube-side material inlet / outlet 4 serves as the tube-side material outlet. The first end cap 12 connects to the outlet of the heat exchange tube 14 and the second tube-side passage 15. In this configuration, the tube-side material flows into the heat exchange tube 14 from the inlet at the end opposite to the first end cap 12, then flows from the outlet of the heat exchange tube 14 into the hollow interior of the first end cap 12, then into the second tube-side passage 15, and finally flows out from the tube-side material outlet. Alternatively, the tube-side material inlet / outlet 4 serves as the tube-side material inlet. The first end cap 12 connects to the inlet of the heat exchange tube 14 and the second tube-side passage 15. In this configuration, the tube-side material flows from the tube-side material inlet into the second tube-side passage 15, then into the hollow interior of the first end cap 12, then into the heat exchange tube 14 from the inlet, and finally flows out from the outlet of the heat exchange tube 14.

[0048] The dual-tube heat exchanger provided by this invention enables heat exchange between shell-side and tube-side materials. The tube-side material passes through the second tube-side channel 15 and the heat exchange tubes 14. When the tube-side material passes through the second tube-side channel 15 in the double-layer shell, it expands the flow area of ​​the tube-side material and forms a multi-stage heat transfer path, allowing the tube-side material to flow through the heat exchange area of ​​the shell-side material twice, thus expanding the heat exchange area between the tube-side and shell-side materials. Furthermore, when the shell-side material is high-temperature and the tube-side material is low-temperature, if the double-layer shell needs to meet thermal protection requirements, the unexchanged low-temperature tube-side material can flow through the second tube-side channel 15 (in this case, the tube-side material's transport path is the second one mentioned above). In this case, the second tube-side channel 15 can act as a water-cooling clamp for the double-layer shell. The first layer prevents the high-temperature shell material from damaging the thermal protection effect of the double-layer shell, ensuring the external temperature of the double-layer shell and reducing safety hazards. If the double-layer shell needs to meet certain insulation requirements, the second tube-side channel 15 can be used to circulate the low-temperature tube-side material that has undergone heat exchange (in this case, the tube-side material transport path is the first one mentioned above). Since the temperature of the low-temperature tube-side material rises after heat exchange, but remains lower than that of the high-temperature shell material, the second tube-side channel 15 can act as an insulation layer for the double-layer shell, preventing excessive ineffective heat loss within the shell-side material heat exchange chamber 21 and ensuring the heat exchange effect between the shell-side and tube-side materials. When the shell-side material is low-temperature and the tube-side material is high-temperature, if the double-layer shell needs to be used as a cooling shell, the first tube-side material transport path is used, and the second tube-side channel 15 circulates the cooled tube-side material. If the double-layer shell needs to be used as an insulation shell, the second tube-side material transport path is used, and the second tube-side channel 15 circulates the high-temperature tube-side material, which can improve the insulation and heat exchange effect.

[0049] In summary, the dual-tube heat exchanger provided by this utility model forms a dual-tube structure by setting a second tube passage 15. It can improve the heat exchange effect by increasing the heat exchange area of ​​the tube-side material and the shell-side material. Furthermore, depending on the flow path of the tube-side material and the initial temperature difference, the second tube passage 15 can be used as a cooling channel or a heat preservation channel for the double-layer shell, thereby improving the adaptability of the dual-tube heat exchanger in different application scenarios.

[0050] In one embodiment, the tube-side material inlet / outlet 4 is located at the end of the second tube-side channel 15 opposite to the first end cap 12. This extends the flow length of the second tube-side channel 15. Preferably, the second tube-side channel 15 covers the entire axial length of the double-layer shell, thereby ensuring the heat exchange effect between the second tube-side channel 15 and the shell-side material heat exchange chamber 21, while also ensuring the cooling effect of the shell-side material heat exchange chamber 21 as a water-cooled structure or the insulation effect as a heat-insulating structure.

[0051] In one embodiment, multiple heat exchange tubes 14 are arranged at intervals between each other, which can greatly increase the conveying capacity of the tube-side material and the heat exchange area between the tube-side material and the shell-side material. (Refer to Appendix) Figure 2 Multiple heat exchange tubes 14 are evenly arranged in the shell-side material heat exchange chamber 21;

[0052] The inlet and outlet of multiple heat exchange tubes 14 are connected to the second tube passage 15 through the first end cap 12.

[0053] In one embodiment, the dual-pass heat exchanger further includes a second end cap, which is a hollow structure with one open end. The second end cap is provided with a tube material inlet / outlet 1. When the tube material adopts the first conveying path described above, the tube material inlet / outlet 1 is the tube material inlet. When the tube material adopts the second conveying path described above, the tube material inlet / outlet 1 is the tube material outlet.

[0054] The second end cap is located on the other tube sheet 5 side. The opening of the second end cap blocks the tube sheet 5. That is, the first end cap 12 and the second end cap are arranged opposite to each other on both sides of the double shell. The second end cap connects the tube side material inlet / outlet 1 and the inlet / outlet of multiple heat exchange tubes 14.

[0055] In this embodiment, the second end cap can concentrate the flow of multiple heat exchange tubes 14 into one, which is convenient for connecting to external tube-side material supply equipment or output equipment.

[0056] In one embodiment, the second end cap is a double-layer end cap, and the inner wall of the double-layer end cap is provided with a third tube passage 16. That is, the second end cap includes an outer end cap 3 and an inner end cap 2, and the inner wall of the outer end cap 3 and the outer wall of the inner end cap 2 enclose the third tube passage 16.

[0057] The third tube passage 16 is connected to the second tube passage 15 at the end away from the first end cap 12, and the tube passage material inlet / outlet 4 is set on the third tube passage 16 and is connected to the second tube passage 15 through the third tube passage 16. The third tube passage 16 can provide thermal protection or insulation for the second end cap.

[0058] In one embodiment, the tube sheet 5 is provided with mounting holes for installing heat exchange tubes 14 and tube sheet guide holes 19 connecting the first end cap, the second end cap, and the second tube-side channel 15. The heat exchange tubes 14 are sealed and installed in the mounting holes, and one tube sheet guide hole 19 connects the second tube-side channel 15 and the first end cap 12, while another tube sheet guide hole 19 connects the second tube-side channel 15 and the third tube-side channel 16. Preferably, multiple tube sheet guide holes 19 are evenly arranged in a ring array to improve the flow guiding efficiency.

[0059] In one specific embodiment, the double-layer shell includes an outer shell 7 and an inner shell 8 coaxially disposed within the outer shell 7, with the inner wall of the outer shell 7 and the outer wall of the inner shell 8 enclosing a second tube passage 15.

[0060] The double-layered head includes a second outer head 3 and a second inner head 2. The inner wall of the second outer head 3 and the outer wall of the second inner head 2 enclose each other to form a third tube-side channel 16. In this embodiment, both the second tube-side channel 15 and the third tube-side channel 16 are annular cavities, which can cover the entire shell-side material heat exchange cavity 21 and the hollow interior of the second head.

[0061] In one embodiment, shell connecting flanges are provided at both ends of the outer shell 7 and the inner shell 8, and shell connecting flanges are provided with shell flange guide holes 18, which are connected to tube sheet guide holes 19.

[0062] The second outer head 3 and the second inner head 2 are provided with a second head connecting flange at their ends. The second head connecting flange, tube sheet 5 and shell connecting flange are fastened together by fasteners 11. The second head connecting flange is provided with a head flange guide hole 17 that connects the tube sheet guide hole 19 and the third tube passage 16.

[0063] The first end cap 12 is provided with a first end cap connecting flange at its end. The first end cap connecting flange, tube sheet 5, and shell connecting flange are fastened together by fasteners 11. The first end cap communicates with the second tube pass channel 15 through the tube sheet guide hole 19. In this embodiment, the installation difficulty of the end cap, tube sheet 5, and double shell can be simplified. Preferably, each flange is a disc-shaped flange, and multiple fasteners 11 are arranged in a ring array. Preferably, the tube sheet 5 is provided with O-rings 20 on the outer and inner sides of the tube sheet guide hole 19 for sealing with the flanges of the end cap and double shell to improve the sealing effect.

[0064] In one preferred embodiment, the shell-side material inlet 13 and the shell-side material outlet 6 are located on both sides of the double-layer shell, thereby increasing the flow distance of the shell-side material.

[0065] Baffles 9 are arranged axially at staggered intervals within the double-layer shell. These baffles 9 further increase the flow distance of the shell-side material, thereby improving the heat exchange efficiency between the shell-side and tube-side materials. In other embodiments, the baffles 9 may also employ other forms of fluid guiding devices, such as multi-pass baffles or other structures that enhance the fluid flow path and turbulence, to further improve heat transfer performance.

[0066] In one preferred embodiment, a spiral guide 10 is axially arranged within the second tube-side channel 15. The spiral guide 10 forces the tube-side material within the second tube-side channel 15 to flow in a spiral pattern, extending the flow path and enhancing turbulence, thereby further strengthening the heat transfer effect. Furthermore, the spiral flow characteristics continuously scour the wall surface of the second tube-side channel 15, inhibiting fouling deposition, preventing localized stagnation, and extending the equipment cleaning and maintenance cycle. In other embodiments, the structure of the spiral guide 10 can be replaced with other designs that guide the fluid to a uniform distribution and increase the fluid travel distance, achieving the same goal of improving heat exchange efficiency.

[0067] The above description is merely an embodiment and does not constitute any limitation on this utility model. Any person skilled in the art can make many possible variations, modifications, or alterations to the technical solution of this utility model without departing from its scope. Therefore, any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of this utility model, without departing from its scope, should fall within the protection scope of this utility model.

Claims

1. A two-tube heat exchanger, characterized in that, It includes a double shell, tube sheet (5), first end cap (12) and at least one heat exchange tube (14); The double-layer shell has a second tube passage (15) arranged in the axial direction inside the shell wall, and the tube sheet (5) is provided at both ends of the double-layer shell in the axial direction. The heat exchange tube (14) is located inside the double shell and penetrates both tube sheets (5). The first end cap (12) is disposed on one of the tube sheets (5) and the first end cap (12) connects the inlet / outlet of the heat exchange tube (14) and the second tube passage (15). The second pipe passage (15) is connected to the pipe material inlet / outlet (4); It also includes a shell-side material inlet (13) and a shell-side material outlet (6) connected to the double-layer shell. The second tube passage (15) can be used as a cooling passage or a heat preservation passage for the double shell, depending on the flow path of the tube material and the initial temperature difference.

2. The two-tube heat exchanger as described in claim 1, characterized in that, The material inlet / outlet (4) of the tube is located at the end of the second tube passage (15) away from the first end cap (12).

3. The two-tube heat exchanger as described in claim 1, characterized in that, The heat exchange tubes (14) are arranged at intervals; The inlet and outlet of each of the multiple heat exchange tubes (14) are connected to the second tube passage (15) through the first end cap (12).

4. The two-tube heat exchanger as described in claim 3, characterized in that, It also includes a second end cap, which is provided with a tube-side material inlet / outlet (1); The second end cap is disposed on the other tube sheet (5) side, and the second end cap is connected to the tube material inlet / outlet (1) and the inlet / outlet of the plurality of heat exchange tubes (14).

5. The two-tube heat exchanger as described in claim 4, characterized in that, The second end cap is a double-layer end cap, and a third tube passage (16) is provided on the inner wall of the double-layer end cap. The third pipe passage (16) is connected to the second pipe passage (15) at the end away from the first end cap (12), and the pipe material inlet / outlet (4) is set on the third pipe passage (16) and is connected to the second pipe passage (15) through the third pipe passage (16).

6. The two-tube heat exchanger as described in claim 5, characterized in that, The tube sheet (5) is provided with mounting holes for installing the heat exchange tube (14) and tube sheet guide holes (19) connecting the first end cap (12), the second end cap and the second tube passage (15).

7. The two-tube heat exchanger as described in claim 6, characterized in that, The double-layer shell includes an outer shell (7) and an inner shell (8) coaxially disposed within the outer shell (7). The inner wall of the outer shell (7) and the outer wall of the inner shell (8) enclose the second tube passage (15). The double-layer end cap includes a second outer end cap (3) and a second inner end cap (2), the inner wall of the second outer end cap (3) and the outer wall of the second inner end cap (2) enclose the third pipe passage (16).

8. The two-tube heat exchanger as described in claim 7, characterized in that, The outer shell (7) and the inner shell (8) are provided with shell connecting flanges at both ends. The shell connecting flanges are provided with shell flange guide holes (18), and the shell flange guide holes (18) are connected to the tube sheet guide holes (19). The second outer end cap (3) and the second inner end cap (2) are provided with a second end cap connecting flange. The second end cap connecting flange, tube sheet (5) and shell connecting flange are fastened together by fasteners (11). The second end cap connecting flange is provided with an end cap flange guide hole (17) that connects the tube sheet guide hole (19) and the third tube passage (16). The first end cap (12) is provided with a first end cap connecting flange at its end. The first end cap connecting flange, tube sheet (5) and shell connecting flange are fastened together by fasteners (11). The first end cap is connected to the second tube passage (15) through the tube sheet guide hole (19).

9. The two-tube heat exchanger as described in any one of claims 1-8, characterized in that, The shell-side material inlet (13) and shell-side material outlet (6) are located on both sides of the double-layer shell; The double-layer shell is provided with baffles (9) arranged alternately along the axial direction.

10. The two-tube heat exchanger as described in any one of claims 1-8, characterized in that, A spiral guide (10) is provided axially inside the second tube passage (15).

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