A shell-and-tube heat exchanger

Abstract

The present application relates to heat exchanger technical field, specifically to a kind of shell-and-tube heat exchanger, including shell, two end covers of shell, two tube sheets and several heat exchange tubes, a spring is arranged in each of the heat exchange tube, each of the spring is made of multiple spring segments, each spring segment is two ends outer diameter is large, middle outer diameter is small, the two ends of spring segment and heat exchange tube inner wall abut, and there is spacing between the middle of spring segment and heat exchange tube inner wall.The present application realizes the purpose of improving heat exchange efficiency by different simplification structure from prior art, realizes the higher adaptability of shell-and-tube heat exchanger under different working conditions by simple change on the basis of existing heat exchanger, has higher thermal efficiency, and prevents scale formation.

Description

Technical Field

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

[0002] A shell-and-tube heat exchanger, also known as a tubular heat exchanger, encloses a tube bundle within a shell, with the tube walls serving as the heat transfer surface. Made of metal, shell-and-tube heat exchangers offer a simple structure and reliable operation. Their operating principle is that one fluid flows through the tubes, while another flows through the shell, exchanging heat through the tube walls.

[0003] Shell-and-tube heat exchangers often have problems such as low heat transfer coefficients and dead zones that are prone to scaling. Improvements to existing shell-and-tube heat exchangers are usually based on these two points. For example, Song Lifa described enhanced heat transfer in the tube side and shell side in "Ideas, Measures, and Development Directions for Shell-and-Tube Heat Exchanger Improvements" (Equipment Management and Maintenance, 2023), p. 112-p. 113. A Chinese patent application with application number and publication number CN101464101A discloses a shell-and-tube heat exchanger with built-in springs in the heat exchange tubes. This patent proposes a solution to improve the heat exchange effect by building springs into the heat exchange tubes. CN 113899228 B improves on this solution and discloses a shell-and-tube heat exchanger comprising a shell, a head, a tube sheet, and a plurality of heat exchange tubes. Each heat exchange tube is provided with a spring, and the spring and the heat exchange tube are loosely 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; each spring is provided with a number of flow-guiding elements at equal intervals, and each flow-guiding element comprises a core shaft, a spiral sheet arranged on the core shaft, and two connecting plates, 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-mentioned 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 flow guide. However, the above structure is relatively complex. 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-mentioned technical problems, the present invention provides a shell and tube heat exchanger, the purpose of which 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 prevention of 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, end covers at both ends of the shell, at least one tube sheet, and a plurality of heat exchange tubes. Each heat exchange tube is provided with a spring, and each spring is composed of a plurality of spring segments. Each spring segment 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 gap 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, the two ends of the heat exchange tube respectively pass through 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 the nut at the end of the outer heat exchange tube and fastened.

[0010] The use of nuts for limiting the connection makes it very convenient to connect and disassemble, and can be quickly repaired and replaced 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, which 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 shakes, 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 flow 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, thereby 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 multiple 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 part 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. 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 positioned and connected to multiple guide plates through a distance tube. The cross-section of the distance tube is "D"-shaped, and the distance tube has a straight surface and an arc-shaped surface. The straight surfaces of every two adjacent distance tubes are opposite or the arc-shaped surfaces of every two adjacent distance tubes are opposite.

[0021] The spacer tube causes the fluid to form vortices when it bypasses the spacer tube, 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 the central axis of the through hole on the guide plate forms an angle with 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, which are in sliding contact with the outer wall of the heat exchange tube. 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 plate.

[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 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 problem of scaling on the outer wall of the heat exchange tube of the shell-side fluid. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0032] Figure 3 It is a structural schematic 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 Magnified view of part C;

[0035] Figure 6 Schematic diagram of the structure 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 accompanying 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. Distance tube; 15. Guide plate; 16. Through hole; 17. Spiral blade. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solutions 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 intended 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, the two heads 2 at both ends of the shell 1, the two tube sheets 3, a plurality of heat exchange tubes 4 and the 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 which 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. This periodic change enables the spring to form self-support inside the heat exchange tube 4, and at the same time forms 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 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 pass through 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. The free end of the spring is screwed onto a nut 8 at the end of the outer heat exchange tube 4 to tighten it.

[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. At the same time, the connection is also relatively stable.

[0043] like Figure 3 and Figure 5 As shown, a spoiler 9 is provided on the spring, 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). The spoiler 9 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 6.

[0044] There is only one spoiler 9, which is fixedly connected to the part of the spring with a small diameter and is close to the tube-side fluid inlet end of the heat exchange tube 4. Its main purpose is to disturb the tube-side fluid at the inlet of the heat exchange tube 4, so that the tube-side fluid quickly develops into turbulent flow. 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 inlet of the heat exchange tube 4 forms an alternating fast and slow change, 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 turbulent flow.

[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 part of the spherical cap, which can increase the effect of being impacted by the tube-side fluid, making it more sensitive to the impact of the tube-side fluid, and also causing the tube-side fluid to reach a turbulent state more quickly in the heat exchange tube 4. The present invention differs from the prior art in that the effect of the spoiler 9 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 low, it can increase the degree of turbulence, causing the tube-side fluid to quickly reach a turbulent state. When the tube-side fluid flow rate increases, the spoiler 9 has a poor rebound effect when impacted by the tube-side fluid, or even no rebound, opening the channel originally blocked by the spoiler 9, reducing resistance, and reducing the pressure drop of the heat exchanger, making the heat exchanger suitable for use in occasions with lower flow rates. This realizes the shell and tube heat exchanger's high adaptability to different working conditions, has high thermal efficiency, and prevents 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 is 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, playing 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. The heat exchanger does not distinguish between vertical and horizontal types.

[0052] The length of the tension spring is relatively short in its natural state, which makes it more convenient to produce, store and transport. Therefore, the large-diameter spring ring 10 on the spring segment 6 of the present invention has a larger 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 to multiple guide plates 15 through a distance tube 14. The cross-section of the distance tube 14 is "D"-shaped, and the distance tube 14 has a straight surface and an arc surface. The straight surfaces of every two adjacent distance tubes 14 are opposite to each other, or the arc surfaces of every two adjacent distance tubes 14 are opposite to each other.

[0054] The adjacent two distance tubes 14 are in a state of facing each other directly or with arc-shaped surfaces. Because the distance tubes 14 are not of regular shape, when the shell-side fluid flows through, different flow paths form different bypasses, which develop into 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. 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.

[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 tube wall of the heat exchange tube 4, strengthens the destruction of the boundary layer of the tube 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 tension, the large-diameter spring ring 10 of the spring section 6 will be elongated, thereby reducing the diameter. After the connecting rod is retracted, due to the restoring force of the spring, the large-diameter spring ring 10 is pressed against the inner wall of the heat exchange tube, 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 which 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). The spring is provided with a spoiler (9), the spoiler (9) is located at the inlet 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). The spoiler (9) is spherically arched toward the outlet of the heat exchange tube (4). 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). 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). 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 distance tube (14). The cross section of the distance tube (14) is "D"-shaped, and the distance tube (14) has a straight surface and an arcuate surface. The straight surfaces of every two adjacent distance tubes (14) are opposite to each other, or the arcuate surfaces of every two adjacent distance tubes (14) are opposite to each other.

2. The shell and tube heat exchanger according to claim 1, characterized in that The two ends of the heat exchange tube (4) respectively pass through 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 screwed onto a nut (8) at the end of the heat exchange tube (4) and fastened.

3. 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.

4. The shell and tube heat exchanger according to claim 1, 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).

5. 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 jacket. 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 plate (3).

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