Shell-and-tube heat exchanger

Abstract

The invention relates to the technical field of heat exchangers, in particular to a shell-and-tube heat exchanger which comprises a shell, two end sockets at the two ends of the shell, two tube plates and a plurality of heat exchange tubes, a spring is arranged in each heat exchange tube, each spring is composed of a plurality of spring sections, and each spring section is large in outer diameter of the two ends and small in outer diameter of the middle. The two ends of the spring section abut against the inner wall of the heat exchange tube, and a gap is formed between the middle of the spring section and the inner wall of the heat exchange tube. According to the shell-and-tube heat exchanger, the purpose of improving the heat exchange efficiency is achieved through a simplified structure different from the prior art, high adaptability of the shell-and-tube heat exchanger to different working conditions is achieved through simple changes on the basis of an existing heat exchanger, high heat efficiency is achieved, and scaling is prevented.

Description

Technical Field

[0001] The invention relates to the technical field of heat exchangers, and in particular to a shell and tube heat exchanger. Background Art

[0002] Shell and tube heat exchanger, also known as shell and tube heat exchanger, refers to a wall-type heat exchanger that encloses the tube bundle in the shell and uses the tube bundle wall as the heat transfer surface. Shell and tube heat exchanger is made of metal materials, with simple structure and reliable operation. Its working principle is that one fluid flows in the tube and the other flows on the shell side, and heat exchange is achieved through the heat exchange tube wall.

[0003] Shell and tube heat exchangers usually have problems such as small heat transfer coefficient and easy scaling in dead flow areas. The improvement of shell and tube heat exchangers in the prior art usually starts from these two points. For example, Song Lifa recorded the enhanced heat transfer of the tube side and the enhanced heat transfer of the shell side in "Ideas, Measures and Development Directions for Improvement of Shell and Tube Heat Exchangers" 2023 Equipment Management and Maintenance, P112-P113, and the Chinese patent with application number and publication number CN101464101A disclosed a shell and tube heat exchanger with built-in springs in the heat exchange tube. The patent proposed a solution of building springs into the heat exchange tube to improve the heat exchange effect. CN 113899228 B improved it and disclosed a shell and tube heat exchanger, including a shell, a head, a tube sheet, and a plurality of heat exchange tubes. A spring is arranged in each heat exchange tube, and the spring and the heat exchange tube are clearance-fitted; at least two steel wires pass through each spring, and each steel wire abuts against the corresponding spring and is connected by spot welding; each steel wire extends from both ends of the corresponding heat exchange tube and is bent; a number of flow-guiding elements are arranged in each spring at the same interval, and each flow-guiding element comprises a core shaft, a spiral sheet arranged on the core shaft, and two connecting plates, and the two ends of the core shaft are rotatably connected to the corresponding connecting plates, and each connecting plate is fixedly connected to the corresponding steel wire.

[0004] The above heat exchanger improves the heat exchange efficiency by disrupting the laminar boundary layer near the inner wall of the heat exchange tube through spring wire and guide piece. However, the above structure is relatively complicated. The length of our company's heat exchanger is usually about 5 meters, and the technical requirements for welding steel wire are quite high, so technical transformation cannot be achieved. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a shell and tube heat exchanger, whose purpose is to provide a simplified structure different from the prior art to achieve the purpose of improving heat exchange efficiency. Another purpose of the present invention is to achieve higher adaptability of the shell and tube heat exchanger to different working conditions through simple changes on the basis of the existing heat exchanger, with higher thermal efficiency and prevent scaling.

[0006] In order to achieve the above object, the technical solution of the present invention is as follows:

[0007] A shell and tube heat exchanger comprises a shell, heads at both ends of the shell, at least one tube sheet and a plurality of heat exchange tubes, each of the heat exchange tubes is provided with a spring, each of the springs is composed of a plurality of spring segments, each of the spring segments has a large outer diameter at both ends and a small outer diameter in the middle, the two ends of the spring segment abut against the inner wall of the heat exchange tube, and there is a distance between the middle of the spring segment and the inner wall of the heat exchange tube.

[0008] The difference between the present invention and the prior art is that the diameter of the spring changes periodically. This periodic change can cause the spring to form an unbalanced state when the tube-side fluid impacts it, thereby causing shaking in the heat exchange tube, disturbing the tube-side fluid in the heat exchange tube, increasing the Reynolds number, and allowing it to be in a turbulent state even at a lower flow rate, thereby having higher adaptability to different working conditions.

[0009] Furthermore, both ends of the heat exchange tube respectively penetrate and extend out of the connected tube sheet, a groove is provided on the heat exchange tube extending out of the tube sheet, an external thread is provided on the outer wall of the heat exchange tube outside the groove, the free end of the spring extends out of the heat exchange tube and bends into the groove, and the free end of the spring is screwed onto a nut at the end of the external heat exchange tube and fastened.

[0010] The use of nuts for limiting the connection makes it easy to connect and disassemble, and allows for quick repair and replacement without damaging the heat exchange tubes. At the same time, the connection is also relatively stable.

[0011] Furthermore, a spoiler is provided on the spring, and the spoiler is located at the inlet of the heat exchange tube (the end where the tube-side fluid enters the heat exchange tube). The spoiler has two arcuate edges, which are open and opposite to each other, and one of the arcuate edges is connected to the middle of the spring segment.

[0012] The spoiler is impacted by the tube-side fluid and vibrates, causing the tube-side fluid flow velocity at the inlet of the heat exchange tube to change alternately between fast and slow. The tube-side fluid flowing in the heat exchange tube forms a large velocity difference, and is then disturbed by the spring to form turbulence.

[0013] Furthermore, the spoiler is spherically arched toward the outlet of the heat exchange tube (the end where the tube-side fluid flows out of the heat exchange tube).

[0014] The spoiler is more sensitive to the impact of the tube-side fluid, so that the tube-side fluid reaches a turbulent state in the heat exchange tube more quickly, achieving higher adaptability of the shell and tube heat exchanger to different working conditions, having higher thermal efficiency, and preventing scaling.

[0015] Furthermore, the spring segment includes a large diameter spring ring, a small diameter spring ring and a plurality of straight section spring rings; the large diameter spring ring is located at both ends of the spring segment, the small diameter spring ring is located in the middle of the spring segment, and the portion between the small diameter spring ring and the large diameter spring ring is the straight section spring ring.

[0016] Furthermore, the outer diameter of the large diameter spring ring is larger than the inner diameter of the heat exchange tube, the outer diameter of the straight section spring ring is equal to the inner diameter of the heat exchange tube in a natural state, and the outer diameter of the small diameter spring ring is less than or equal to 30% of the inner diameter of the heat exchange tube.

[0017] Furthermore, in each of the spring segments, the number of turns of each large-diameter spring ring is 1-2, the number of turns of the small-diameter spring ring is 2-3, and the number of turns of each straight-segment spring ring is 5-15.

[0018] The above arrangement enables the spring section to be in a relatively stable position in the heat exchange tube, regardless of whether the heat exchanger is vertical or horizontal.

[0019] Furthermore, the spring is a tension spring, and when the spring is located in the heat exchange tube, any point on the spring is in a tensioned state.

[0020] Furthermore, a tie rod is connected between the two tube sheets, and the tie rod is connected to a plurality of guide plates through a spacing tube. The cross-section of the spacing tube is "D"-shaped, and the spacing tube has a straight surface and an arc-shaped surface. The straight surfaces of every two adjacent spacing tubes are opposite or the arc-shaped surfaces of every two adjacent spacing tubes are opposite.

[0021] The spacer tube causes the fluid to form a vortex when the fluid bypasses it, promoting fluid turbulence.

[0022] Furthermore, the guide plate is provided with a through hole for the heat exchange tube to pass through, the diameter of the through hole is larger than the outer diameter of the heat exchange tube, and an angle is formed between the central axis of the through hole on the guide plate and the central axis of the heat exchange tube.

[0023] The through holes enable the shell-side fluid to flow through, increasing the turbulence of the shell-side fluid and reducing the pressure drop. The shell-side fluid flowing through the through holes impacts the heat exchange tube wall, thereby strengthening the destruction of the boundary layer of the heat exchange tube wall and improving the heat exchange efficiency.

[0024] Furthermore, the heat exchange tube is outer-coated with a plurality of spiral blades, the spiral blades are in sliding contact with the outer wall of the heat exchange tube, and both ends of the spiral blades respectively contact two adjacent guide plates or one end of the spiral blade contacts the guide plate and the other end contacts the tube sheet.

[0025] Furthermore, the outer edge of the spiral blade is inclined toward the inlet direction of the shell-side fluid.

[0026] The present invention has the following beneficial effects:

[0027] 1. The present invention improves the heat exchange efficiency with a simple structure, reduces the pressure drop of the heat exchanger, reduces the probability of scaling, and is suitable for use in working conditions with different flow rates.

[0028] 2. The present invention has strong adaptability to both low and high flow rates. It can promote fluid turbulence and improve heat exchange efficiency at low flow rates, and can avoid fluid and reduce pressure drop at high flow rates.

[0029] 3. The tube-side fluid of the present invention destroys the interface of the tube-side by spring vibration, thereby improving the heat exchange efficiency. The shell-side fluid destroys the interface by the guidance of the fixed-distance tube and the rotation of the spiral blade, thereby improving the heat exchange efficiency. At the same time, the rotation of the spiral blade solves the scaling problem of the outer wall of the heat exchange tube of the shell-side fluid. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a sectional front view of the present invention;

[0031] Figure 2 yes Figure 1 AA section view;

[0032] Figure 3 It is a schematic structural diagram of the heat exchange tube of the present invention;

[0033] Figure 4 yes Figure 3 A magnified view of part B;

[0034] Figure 5 yes Figure 3 Enlarged view of part C;

[0035] Figure 6 It is a structural schematic diagram of the spring segment of the present invention (tension state);

[0036] Figure 7 It is a structural schematic diagram of the spiral blade of the present invention.

[0037] The numbers in the attached drawings are: 1, shell; 2, head; 3, tube sheet; 4, heat exchange tube; 5, floating head cover; 6, spring segment; 7, slot; 8, nut; 9, spoiler; 10, large diameter spring ring; 11, small diameter spring ring; 12, straight section spring ring; 13, pull rod; 14, fixed distance tube; 15, guide plate; 16, through hole; 17, spiral blade. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0039] A shell and tube heat exchanger comprises a shell 1, two heads 2 at both ends of the shell 1, two tube sheets 3 and a plurality of heat exchange tubes 4, and also comprises a floating head cover 5. Figure 1 and Figure 2As shown, the shell 1, two heads 2 at both ends of the shell 1, two tube sheets 3, a plurality of heat exchange tubes 4 and a floating head cover 5 constitute a floating head heat exchanger; each of the heat exchange tubes 4 is provided with a spring, and each of the springs is composed of a plurality of spring segments 6, each of the spring segments 6 has a large outer diameter at both ends and a small outer diameter in the middle, the two ends of the spring segment 6 abut against the inner wall of the heat exchange tube 4, and there is a gap between the middle of the spring segment 6 and the inner wall of the heat exchange tube 4.

[0040] like Figure 3 As shown, the difference between the present invention and the prior art is that the diameter of the spring changes periodically, and this periodic change can make the spring self-supporting inside the heat exchange tube 4, and at the same time form an unbalanced state when the tube-side fluid impacts, thereby forming shaking in the heat exchange tube, disturbing the tube-side fluid in the heat exchange tube 4, increasing the Reynolds number, and making it possible to be in a turbulent state even at a lower flow rate, and having higher adaptability to different working conditions.

[0041] like Figure 3 and Figure 4 As shown, both ends of the heat exchange tube 4 respectively penetrate and extend out of the connected tube sheet 3, a groove 7 is provided on the heat exchange tube 4 extending out of the tube sheet 3, an external thread is provided on the outer wall of the heat exchange tube 4 outside the groove 7, the free end of the spring extends out of the heat exchange tube 4 and bends into the groove 7, and the free end of the spring is screwed on the nut 8 at the end of the outer heat exchange tube 4 to tighten.

[0042] The nut 8 is used for limiting, and the connection and disassembly of the spring are very convenient, and can be quickly repaired and replaced without damaging the heat exchange tube 4, while the connection is also relatively stable.

[0043] like Figure 3 and Figure 5 As shown, the spring is provided with a spoiler 9, and the spoiler 9 is located at the inlet of the heat exchange tube 4 (the end where the tube-side fluid enters the heat exchange tube), and the spoiler 9 has two arcuate edges, which are in an open and opposite state, and one of the arcuate edges is connected to the middle of the spring segment 6.

[0044] There is only one spoiler 9, which is fixedly connected to the part of the spring with a small diameter and close to the tube-side fluid entrance end of the heat exchange tube 4. Its main purpose is to disturb the tube-side fluid at the entrance of the heat exchange tube 4, so that the tube-side fluid quickly develops into turbulence. Because the spoiler 9 is connected to the spring, the spoiler 9 does not block the fluid flow all the time, but is in a state of shaking due to the impact of the tube-side fluid, so that the flow velocity of the tube-side fluid in the entrance of the heat exchange tube 4 changes alternately between fast and slow, and the tube-side fluid flowing in the heat exchange tube forms a large flow velocity difference, which is then disturbed by the spring to form turbulence.

[0045] The spoiler 9 is spherically arched toward the outlet of the heat exchange tube 4 (the end where the tube-side fluid flows out of the heat exchange tube).

[0046] That is, the spoiler 9 is a part of the spherical crown, which can increase the effect of being impacted by the tube-side fluid, is more sensitive to the impact of the tube-side fluid, and also enables the tube-side fluid to reach a turbulent state faster in the heat exchange tube 4. The present invention is different from the prior art in that the influence of the spoiler 9 of the present invention on the resistance of the tube-side fluid does not increase continuously with the increase of the tube-side fluid resistance. When the tube-side fluid flow rate is relatively low, it can increase the degree of turbulence, so that the tube-side fluid can quickly achieve a turbulent state. After the tube-side fluid flow rate increases, the rebound effect of the spoiler 9 when impacted by the tube-side fluid becomes worse, or even does not rebound, opening the channel originally blocked by the spoiler 9, reducing the resistance, and reducing the pressure drop of the heat exchanger, so that the heat exchanger can be used in occasions with lower flow rates, realizing the higher adaptability of the shell and tube heat exchanger to different working conditions, having higher thermal efficiency, and preventing scaling. At the same time, although the tube-side fluid in a heat exchange tube 4 will form alternating fast and slow flow rates, after the multiple heat exchange tubes 4 are balanced, the overall flow rate is relatively stable, so there will be no water hammer effect.

[0047] like Figure 6 As shown, the spring segment 6 includes a large diameter spring ring 10, a small diameter spring ring 11 and a plurality of straight section spring rings 12; the large diameter spring ring 10 is located at both ends of the spring segment 6, the small diameter spring ring 11 is located in the middle of the spring segment 6, and the portion between the small diameter spring ring 11 and the large diameter spring ring 10 is the straight section spring ring 12.

[0048] The outer diameter of the large diameter spring ring 10 is larger than the inner diameter of the heat exchange tube 4 , the outer diameter of the straight section spring ring 12 is equal to the inner diameter of the heat exchange tube 4 in a natural state, and the outer diameter of the small diameter spring ring 11 is less than or equal to 30% of the inner diameter of the heat exchange tube 4 .

[0049] In each of the spring segments 6, the number of turns of each of the large-diameter spring rings 10 is 1-2, the number of turns of the small-diameter spring ring 11 is 2-3, and the number of turns of each of the straight-segment spring rings 12 is 5-15.

[0050] The spring is a tension spring. When the spring is located in the heat exchange tube 4, any point on the spring is in a tensioned state.

[0051] The diameter of the large diameter spring ring 10 is larger than the inner diameter of the heat exchange tube 4. When located in the heat exchange tube 4, it can effectively abut the inner wall of the heat exchange tube 4 to play a supporting role, so that the small diameter spring ring 11 and the straight section spring ring 12 are in a stretched suspended state, and the spring section 6 can be in a relatively stable position in the heat exchange tube 4, regardless of whether the heat exchanger is vertical or horizontal.

[0052] The length of the tension spring is relatively short in its natural state, and it is relatively convenient to produce, store and transport. Therefore, the large-diameter spring ring 10 on the spring segment 6 of the present invention has a relatively large diameter, and needs to be relatively reduced when the spring is in a stretched state. After the tension spring is stretched, it can form a tensioned state, so that the straight section spring ring 12 remains in a suspended state, forming a better turbulence effect.

[0053] A tie rod 13 is connected between the two tube sheets 3, and the tie rod 13 is positioned and connected with a plurality of guide plates 15 through a spacing tube 14. The cross-section of the spacing tube 14 is "D"-shaped, and the spacing tube 14 has a straight surface and an arc surface. The straight surfaces of every two adjacent spacing tubes 14 are opposite to each other, or the arc surfaces of every two adjacent spacing tubes 14 are opposite to each other.

[0054] Two adjacent distance tubes 14 are in a state of facing each other directly or with arcuate surfaces. Since the distance tubes 14 are not of regular shape, when the shell-side fluid flows through, different flow paths form different bypasses, develop vortices, and promote fluid turbulence.

[0055] The guide plate 15 is provided with a through hole 16 for the heat exchange tube 4 to pass through. The diameter of the through hole 16 is larger than the outer diameter of the heat exchange tube 4. The through hole 16 on the guide plate 15 is inclined, and the central axis of the through hole 16 on the guide plate 15 forms an angle with the central axis of the heat exchange tube 4.

[0056] like Figure 7 As shown, the heat exchange tube 4 is provided with a plurality of spiral blades 17, and the spiral blades 17 are in sliding contact with the outer wall of the heat exchange tube 4, and the two ends of the spiral blades 17 are respectively in contact with two adjacent guide plates 15 or one end of the spiral blade 17 is in contact with the guide plate 15 and the other end is in contact with the tube sheet 3.

[0057] The larger through hole 16 allows the shell-side fluid to flow through, increasing the turbulence of the shell-side fluid and reducing the pressure drop. The through hole 16 is not parallel to the central axis of the heat exchange tube 4, so that the shell-side fluid flowing through the through hole 16 impacts the wall of the heat exchange tube 4, strengthens the destruction of the boundary layer of the wall of the heat exchange tube 4, and improves the heat exchange efficiency.

[0058] The outer edge of the spiral blade 17 is inclined toward the inlet direction of the shell-side fluid, and the spiral blade 17 is impacted by the fluid passing through the through hole 16 and rotates.

[0059] When installing the spring of the present invention, a connecting rod is used to pass through the heat exchange tube 4, and then one end of the spring is fixed on the connecting rod. When the connecting rod is retracted, the spring is pulled through the heat exchange tube 4. Under the action of the pulling force, the large-diameter spring ring 10 of the spring section 6 will be elongated, thereby reducing the diameter. After the connecting rod is retracted, the large-diameter spring ring 10 is pressed against the inner wall of the heat exchange tube due to the restoring force of the spring, and the straight section spring ring 12 is in a tensioned state.

Claims

1. A shell and tube heat exchanger, comprising a shell (1), heads (2) at both ends of the shell (1), a tube sheet (3) and a plurality of heat exchange tubes (4), each of the heat exchange tubes (4) being provided with a spring, characterized in that: Each of the springs is composed of a plurality of spring segments (6), each of the spring segments (6) having a large outer diameter at both ends and a small outer diameter in the middle, the two ends of the spring segment (6) abutting against the inner wall of the heat exchange tube (4), and a distance between the middle of the spring segment (6) and the inner wall of the heat exchange tube (4).

2. The shell and tube heat exchanger according to claim 1, characterized in that: The two ends of the heat exchange tube (4) respectively penetrate and extend out of the connected tube sheet (3); a groove (7) is provided on the heat exchange tube (4) extending out of the tube sheet (3); an external thread is provided on the outer wall of the heat exchange tube (4) outside the groove (7); the free end of the spring extends out of the heat exchange tube (4) and is bent into the groove (7); the free end of the spring is fastened by a nut (8) screwed onto the end of the outer heat exchange tube (4).

3. The shell and tube heat exchanger according to claim 1, characterized in that: The spring is provided with a spoiler (9), the spoiler (9) is located at the entrance of the heat exchange tube (4), the spoiler (9) has two arcuate edges, the two arcuate edges are in an open and opposite state, and one of the arcuate edges is connected to the middle of the spring segment (6).

4. The shell and tube heat exchanger according to claim 3, characterized in that: The spoiler (9) is spherically arched toward the outlet of the heat exchange tube (4).

5. The shell and tube heat exchanger according to claim 1, characterized in that: The spring segment (6) comprises a large-diameter spring ring (10), a small-diameter spring ring (11) and a plurality of straight-section spring rings (12); the large-diameter spring ring (10) is located at both ends of the spring segment (6), the small-diameter spring ring (11) is located in the middle of the spring segment (6), and the portion between the small-diameter spring ring (11) and the large-diameter spring ring (10) is the straight-section spring ring (12).

6. The shell and tube heat exchanger according to claim 5, characterized in that: The outer diameter of the large-diameter spring ring (10) is greater than the inner diameter of the heat exchange tube (4), the outer diameter of the straight section spring ring (12) is equal to the inner diameter of the heat exchange tube (4) in a natural state, and the outer diameter of the small-diameter spring ring (11) is less than or equal to 30% of the inner diameter of the heat exchange tube (4).

7. The shell and tube heat exchanger according to claim 1, characterized in that: The spring is a tension spring. When the spring is located in the heat exchange tube (4), any point on the spring is in a tensioned state.

8. The shell and tube heat exchanger according to any one of claims 1 to 7, characterized in that: A tie rod (13) is connected between the two tube sheets (3), and the tie rod (13) is positioned and connected to a plurality of guide plates (15) via a spacing tube (14). The spacing tube (14) has a "D"-shaped cross section, and the spacing tube (14) has a straight surface and an arcuate surface. The straight surfaces of every two adjacent spacing tubes (14) are opposite to each other, or the arcuate surfaces of every two adjacent spacing tubes (14) are opposite to each other.

9. The shell and tube heat exchanger according to claim 8, characterized in that: The guide plate (15) is provided with a through hole (16) for the heat exchange tube (4) to pass through, the diameter of the through hole (16) is larger than the outer diameter of the heat exchange tube (4), and the central axis of the through hole (16) on the guide plate (15) forms an angle with the central axis of the heat exchange tube (4).

10. The shell and tube heat exchanger according to claim 1, characterized in that: The heat exchange tube (4) is provided with a plurality of spiral blades (17) on its outer sleeve. The spiral blades (17) are in sliding contact with the outer wall of the heat exchange tube (4). The two ends of the spiral blades (17) respectively contact two adjacent guide plates (15), or one end of the spiral blade (17) contacts the guide plate (15) and the other end contacts the tube sheet (3).

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