Leak-proof tube-in-shell heat exchanger

Abstract

The application discloses a leak-proof tube-shell heat exchanger, which comprises a fixed shell, two tube plates, several heat exchange tubes, a shell-side inlet, a shell-side outlet, a tube-side inlet, a tube-side outlet and several baffles, the clearance between the baffle end of each baffle and the inner wall of the shell is larger than the clearance between the rest of the outer circumference of each baffle and the inner wall of the shell, and the baffle ends of two adjacent baffles are oppositely arranged in the radial direction; an annular plate is arranged in the clearance on the axial side of each baffle, the radial outer end of the annular plate is connected with the inner wall of the shell, the radial inner end of the annular plate is located on the radial inner side of the rest of the outer circumference of the corresponding baffle, and the baffle end of each baffle is located on the radial inner side of the radial inner ends of all the annular plates; and the sum of the clearances between each baffle and the annular plates on the two sides of the baffle in the axial direction is smaller than the minimum clearance between the baffle and the inner wall of the shell. The application not only prevents the formation of leakage, improves the heat exchange efficiency, reduces vibration and noise, prolongs the service life, and has the advantages of simple manufacturing, installation and maintenance, and wide application range.

Description

Technical Field

[0001] This invention relates to a shell-and-tube heat exchanger, and more particularly to a leak-proof shell-and-tube heat exchanger with internal baffles. Background Technology

[0002] Heat exchangers, as important industrial equipment, are widely used in various industries such as chemical, petroleum, and energy. The basic function of a heat exchanger is to transfer heat from one fluid medium to another through the tube walls, achieving the purpose of heating or cooling. In the design of a heat exchanger, the hot fluids in the shell and tube sides exchange heat through the heat exchanger's heat transfer walls, and the heat exchange efficiency directly affects the performance of the heat exchanger.

[0003] In traditional shell-and-tube heat exchangers, internal baffles (also called deflectors) guide the shell-side fluid through the tube bundle region to improve shell-side heat transfer efficiency. However, a certain gap is usually left between the baffle and the shell. This is designed for manufacturing, installation, and thermal expansion considerations, and the gap between the baffle and the shell is specified by TEMA standards or the national standard GB / T151. However, the gap between the shell and the baffle can easily cause the fluid to bypass the baffle and flow directly through the gap between the shell and the baffle. This phenomenon is called leakage, bypass flow, or short-circuit flow. Leakage between the shell and the baffle hardly contacts the heat transfer area and is ineffective from a heat transfer perspective. It directly reduces the contact area between the shell-side fluid and the tube bundle, reduces the heat transfer effect, and thus affects the overall efficiency of the heat exchanger. This problem becomes particularly pronounced at low Reynolds numbers on the shell side. At the same time, excessive clearance can lead to unstable fluid flow, which may cause turbulence or recirculation (vortexes) around the baffle. This unstable flow not only increases pressure drop and system energy consumption, but may also cause baffle vibration or even mechanical resonance. These vibrations will accelerate equipment wear, shorten the service life of the heat exchanger, and bring about significant noise problems.

[0004] Currently, leakage is typically reduced by increasing the baffle spacing, reducing the gap between the shell and the baffles, filling with high-temperature sealing materials, or adding elastic baffles. However, these measures still have shortcomings: increasing the baffle spacing can reduce the pressure loss of the liquid through the tube bundle inside the shell, indirectly reducing leakage, but this method significantly reduces the through flow velocity, severely affecting heat exchanger performance; reducing the gap between the shell and the baffles is a straightforward and effective solution to reduce fluid bypass, but the gap width given in heat exchanger standards is an industrial reference value based on performance, installation, and manufacturing costs, making precise control of these tolerances very difficult in large-scale production. This places higher demands on production equipment and processes, increasing costs and process complexity, and posing risks of incompatibility and installation difficulties. Aging and wear of the filling material also affect its long-term performance and make maintenance difficult. Furthermore, while the elastic baffles can seal the gap between the shell and the baffles in the initial stages of operation, as operating time increases, medium fouling, impurities, and fatigue of the elastic material itself can lead to seal failure, resulting in later maintenance costs for baffle repair or replacement. Simultaneously, these elastic baffles are susceptible to vibration from turbulence and recirculation at the baffle edges, generating noise and increasing the risk of shell wear. Existing solutions fail to meet the heat exchanger's requirements in terms of performance, installation and manufacturing costs, and maintainability. Summary of the Invention

[0005] The purpose of this invention is to address the above-mentioned shortcomings of the prior art by providing a leak-proof shell-and-tube heat exchanger. This not only prevents leakage and improves heat exchange efficiency, but also reduces vibration and noise, extends service life, and has the advantages of being easy to manufacture, install, and maintain, and has a wide range of applications.

[0006] To achieve the above objectives, the present invention provides a leak-proof shell-and-tube heat exchanger, comprising a fixed shell, two tube sheets, several heat exchange tubes, a shell-side inlet, a shell-side outlet, a tube-side inlet, a tube-side outlet, and several baffles. The gap between the baffle end of each baffle and the inner wall of the shell is greater than the gap between the remaining outer circumference and the inner wall of the shell. The baffle ends of adjacent baffles are arranged in opposite radial directions. The invention is characterized in that: annular plates are spaced apart on both sides of the axial direction of each baffle. The radial outer end of the annular plate is connected to the inner wall of the shell, and the radial inner end of the annular plate is located radially inner to the remaining outer circumference of the corresponding baffle. The baffle end of each baffle is located radially inner to the radial inner end of all the annular plates. The sum of the axial gaps between each baffle and the annular plates on both sides is less than the minimum gap between the baffle and the inner wall of the shell.

[0007] This invention is based on the principle that fluids tend to follow the path of least pressure loss. By placing annular plates on both sides of a baffle, a structure is formed where two annular plates sandwich the baffle. The sum of the axial clearances between each baffle and the annular plates on either side is less than the minimum clearance between the baffle and the inner wall of the shell. The gap between the shell and the baffle is transformed from a straight, unobstructed leakage channel into a narrow reciprocating flow channel. The pressure loss required to overcome through the gap between the baffle and the shell is significantly increased. The enormous pressure loss required to pass through this narrow channel reduces the leakage flow rate to near-blockage. This not only prevents leakage and improves heat exchange efficiency but also avoids turbulence caused by leakage, vibration of the baffle due to recirculation, and noise. Furthermore, due to the gap between the shell and the baffle, and between the annular plates and the baffle... There is no substantial connection between the baffles, and gaps still exist, allowing for relative displacement between them. This facilitates positional adjustment during installation and eliminates secondary stress on the wall caused by thermal expansion. In addition, the annular plate structure is simple and strong, maintaining structural safety and expected function during long-term operation, thus extending its service life. When fouling accumulates in the narrow reciprocating channel formed by the annular plate and the baffles, the flow cross-section of the narrow reciprocating channel will further shrink, and the pressure loss that needs to be overcome for flow will further increase. Leakage between the shell and the baffles will be more difficult to form, exhibiting a self-reinforcing function. Furthermore, it is easy to manufacture, install, and maintain. The annular plate can be flexibly adjusted according to different heat exchanger structures and operating conditions, making it suitable for heat exchangers of different models and sizes, with a wide range of applications.

[0008] As a further improvement of the present invention, the radial length of each annular plate is greater than 150% of the minimum gap between the baffle plate and the inner wall of the shell; this ensures that the narrow reciprocating flow channel between the annular plate and the baffle plate has a large length, further improving the blocking effect and preventing leakage.

[0009] As a further improvement of the present invention, the thickness of each annular plate is greater than the thickness of each baffle plate; this ensures that the annular plate has sufficient strength and reduces vibration.

[0010] As a further improvement of the present invention, the thickness of each annular plate is less than 50% of the baffle spacing; this can reduce the influence of the annular plates on the flow regime of the fluid during baffle flow, and ensure the shell-side Reynolds number and heat transfer effect.

[0011] As a further improvement of the present invention, the radial outer end of the annular plate is connected to the inner wall of the shell by bonding or welding.

[0012] As a further improvement of the present invention, each baffle is connected to the tube sheet by several tie rods, and several fixed-distance tubes are provided outside each tie rod between each baffle and between the tube sheet and adjacent baffles; this facilitates the installation and fixing of the baffles.

[0013] In summary, this invention not only prevents leakage and improves heat exchange efficiency, but also reduces vibration and noise, extends service life, and has the advantages of being easy to manufacture, install and maintain, and has a wide range of applications. Attached Figure Description

[0014] Figure 1 This is a front view of an embodiment of the present invention.

[0015] Figure 2 for Figure 1 The image shows a magnified view of a section containing a three-baffle plate.

[0016] Figure 3 for Figure 1 Enlarged view of the area.

[0017] Figure 4 for Figure 1 A front view of a baffle plate and two annular plates inside a section of the casing.

[0018] Figure 5 for Figure 4 BB cross-sectional view. Detailed Implementation

[0019] The present invention will be further described below with reference to the accompanying drawings and using a BEM heat exchanger as an example.

[0020] like Figures 1 to 5As shown, this embodiment of a leak-proof shell-and-tube heat exchanger includes a fixed shell 1, two tube sheets 2 and 3, several heat exchange tubes 4, a shell-side inlet 7, a shell-side outlet 8, a tube-side inlet 5, a tube-side outlet 6, and six baffles 9. The heat exchange tubes 4 all pass through the two tube sheets 2 and 3 and are welded and fixed together. Each baffle 9 has several tube holes through which the heat exchange tubes 4 can pass. Each baffle 9 is connected to a tube sheet 2 by several tie rods 10. One end of each tie rod 10 is threaded to a tube sheet 2, and the other end of each tie rod 10 passing through all the baffles 9 is provided with a fastening nut for easy installation and fixation of the baffles 9. Several spacer tubes 11 are provided outside each tie rod 10, located between each baffle 9 and between the tube sheet 2 and adjacent baffles 9. The outer diameter of the spacer tubes 11 is larger than the tube holes and is welded to the baffles 9. The gap between the baffle end 9a of each baffle 9 and the inner wall of the shell is greater than [missing information]. The remaining outer circumference and the inner wall of the shell are not separated. The deflection ends 9a of two adjacent baffles 9 are arranged in opposite directions in the radial direction. An annular plate 12 is provided on both sides of the axial direction of each baffle 9. The radial outer end of the annular plate 12 is connected to the inner wall of the shell by bonding or welding. The radial inner end of the annular plate 12 is located on the radial inner side of the remaining outer circumference of the corresponding baffle 9. The deflection ends 9a of each baffle 9 are located on the radial inner side of the radial inner ends of all annular plates 12. The sum of the axial gaps a1+a2 between each baffle 9 and the annular plates 12 on both sides is less than the minimum gap a3 between the baffle 9 and the inner wall of the shell. The radial length b1 of each annular plate 12 is greater than 150% of the minimum gap a3 between the baffle 9 and the inner wall of the shell. The thickness c1 of each annular plate 12 is greater than the thickness c2 of each baffle 9. The thickness c1 of each annular plate is less than 50% of the baffle spacing c3.

[0021] The device is a liquid-liquid heat exchanger, with the hot medium flowing on the shell side and the cold medium flowing on the tube side. It adopts a pure counter-current heat exchange method. The gap area between the baffle end 9a of each baffle plate 9 and the radial inner end of the two annular plates 12 on the radial surface can be used for the liquid to flow on the shell side.

[0022] This invention is based on the principle that fluids tend to follow the path of least pressure loss. By setting two annular plates 12 in the gap between the two sides of the baffle 9, a structure is formed in which the two annular plates 12 sandwich the baffle 9. The sum of the axial gaps a1+a2 between each baffle 9 and the annular plates 12 on both sides is less than the minimum gap a3 between the baffle 9 and the inner wall of the shell. The gap between the shell 1 and the baffle 9 is transformed from a straight and unobstructed leakage channel into a narrow reciprocating flow channel 13. The pressure loss that needs to be overcome through the gap between the baffle 9 and the shell will be greatly increased. The huge pressure loss required to pass through this narrow channel will reduce the leakage flow to almost blockage. This not only prevents leakage and improves heat exchange efficiency, but also avoids turbulence caused by leakage, vibration and noise of the baffle 9 caused by recirculation. At the same time, due to the gap between the shell 1 and the baffle 9, and the annular plates 12 There is no substantial connection between the annular plate 12 and the baffle plate 9, and a gap still exists between them. Relative displacement can still occur between them, which facilitates position adjustment during the installation stage and eliminates secondary stress on the wall caused by thermal expansion. In addition, the annular plate 12 has a simple structure, small radial length dimension, and good strength, which can maintain structural safety and expected function during long-term operation and extend its service life. When fouling accumulates in the narrow reciprocating channel 13 between the annular plate 12 and the baffle plate 9, the flow cross section of the narrow reciprocating channel 13 will be further reduced, and the pressure loss that needs to be overcome for flow will be further increased. Leakage between the shell 1 and the baffle plate 9 will be more difficult to form, which can enhance the function. It also has the advantages of simple manufacturing, installation and maintenance. The annular plate 12 can be flexibly adjusted according to different heat exchanger structures and operating conditions, and is suitable for heat exchangers of different models and sizes, with a wide range of applications.

[0023] The radial length b1 of each annular plate 12 is greater than 150% of the minimum gap a3 between the baffle plate 9 and the inner wall of the shell, which can ensure that the reciprocating flow channel 13 between the annular plate 12 and the baffle plate 9 has a large length, further improving the blocking effect and preventing leakage.

[0024] The thickness c1 of each annular plate 12 is greater than the thickness c2 of each baffle plate 9, which can ensure that the annular plate has sufficient strength and reduce vibration;

[0025] The thickness c1 of each annular plate is less than 50% of the baffle spacing c3, ​​which can reduce the influence of the annular plate on the flow state of the liquid during baffle flow and ensure the shell-side Reynolds number and heat transfer effect.

[0026] When applying this patent, in cases with different shell-side Reynolds numbers (representing the liquid flow state: laminar or turbulent), this invention can reduce leakage between the shell and baffle by 85%-100%, and correspondingly increase the shell-side heat transfer coefficient by 5-30%. Since more medium participates in effective heat exchange on the shell side of the heat exchanger, the heat transfer performance is enhanced. Therefore, in thermal design, corrections need to be made based on standard heat exchanger designs: when the shell-side Reynolds number is less than 3000, the shell-side heat transfer coefficient needs to be calculated by +20%; when the shell-side Reynolds number is between 3000 and 6000, the shell-side heat transfer coefficient needs to be calculated by +150%; when the shell-side Reynolds number is greater than 6000, the shell-side heat transfer coefficient needs to be calculated by +10%. Because a larger volume of medium participates in effective heat exchange, providing greater heat capacity, the final equipment volume can be reduced by 5%-25%.

[0027] In this embodiment, the heat exchanger shell 1 has an inner diameter of 600mm and is equipped with 640 heat exchange tubes 4 of φ16×1, arranged in an equilateral triangle. Six baffles 9 and six sets of twelve annular plates 12 are installed on the shell side. The baffles 9 are spaced 200mm apart, and the annular plates 12 are 5mm thick. The hot medium inlet is at 80 degrees, flowing in from the shell-side inlet 7 and exiting from the shell-side outlet 8. The cold medium inlet is at 25 degrees, flowing in from the tube-side inlet 5 and exiting from the tube-side outlet 6. The hot medium flow rate is 1.5 times that of the cold medium. The shell-side average Reynolds number is 1100, and the tube-side average Reynolds number is 700. The double annular plate leakage blocking mechanism reduces the leakage rate between the shell and baffles from 28% to 0% of the total flow rate, increases the shell-side heat transfer coefficient by 18%, and increases the equipment area margin by 20%.

[0028] The above embodiments have been used to illustrate the invention, but it should be understood that the above embodiments are for illustrative purposes only and are not intended to limit the invention to the scope of the described embodiments.

Claims

1. A leak-proof shell-and-tube heat exchanger, comprising a fixed shell, two tube sheets, several heat exchange tubes, a shell-side inlet, a shell-side outlet, a tube-side inlet, a tube-side outlet, and several baffles, wherein the gap between the baffle end of each baffle and the inner wall of the shell is greater than the gap between the remaining outer circumference and the inner wall of the shell, and the baffle ends of adjacent baffles are arranged in opposite radial directions; characterized in that: Each baffle plate is provided with an annular plate on both sides of its axial direction with a gap. The outer radial end of the annular plate is connected to the inner wall of the shell, and the inner radial end of the annular plate is located on the inner radial side of the remaining outer circumference of the corresponding baffle plate. The baffle end of each baffle plate is located on the inner radial side of the inner radial end of all the annular plates. The sum of the axial gaps between each baffle plate and the annular plates on both sides is less than the minimum gap between the baffle plate and the inner wall of the shell.

2. The leak-proof shell-and-tube heat exchanger as described in claim 1, characterized in that: The radial length of each annular plate is greater than 150% of the minimum clearance between the baffle plate and the inner wall of the shell.

3. A leak-proof shell-and-tube heat exchanger as described in claim 1 or 2, characterized in that: The thickness of each annular plate is greater than the thickness of each baffle plate.

4. A leak-proof shell-and-tube heat exchanger as described in claim 3, characterized in that: The thickness of each annular plate is less than 50% of the distance between the baffles.

5. A leak-proof shell-and-tube heat exchanger as described in claim 4, characterized in that: The radial outer end of the annular plate is connected to the inner wall of the shell by bonding or welding.

6. A leak-proof shell-and-tube heat exchanger as described in claim 5, characterized in that: Each baffle is connected to the tube sheet by several tie rods, and several fixed-distance tubes are provided outside each tie rod between each baffle and between the tube sheet and adjacent baffles.

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