Thermal stress compensation tube bundle heat exchange structure

Abstract

A kind of heat stress compensation tube bundle heat exchange structure contains cylinder, two ends fixed head and movable head, and several heat exchange tubes in cylinder, first tube plate is clamped between fixed head and cylinder, the other end of cylinder is equipped with adaptive second tube plate, its outwardly extending movable tube plate skirt and connect movable head;Corresponding end wall of cylinder is recessed packing groove, and second tube plate is surrounded by packing space;Movable tube plate skirt outside is equipped with packing gland, its lug enters packing groove and extrudes packing, so that packing and second tube plate abut;Shell side inlet and outlet are on both sides of cylinder, fixed head and movable head have tube side outlet and inlet respectively;Heat exchange tube is connected with tube side inlet and outlet by two tube plates, and tube side medium enters heat exchange tube through inlet, and is discharged from outlet after heat exchange with shell side medium.The utility model solves the problems that traditional heat exchanger is easy to be damaged by thermal stress when temperature difference is large, sealing reliability is insufficient, shell side medium flow resistance is large, and stable heat exchange and convenient maintenance are difficult to be considered, realizes temperature difference adaptation, reliable sealing and efficient heat exchange.

Description

Technical Field

[0001] This utility model belongs to the field of heat exchange, and in particular relates to a heat exchange structure for thermal stress compensation tube bundles. Background Technology

[0002] Heat exchange technology is a core energy transfer process in industries such as industry, energy, and HVAC. It enables fluids at different temperatures to exchange heat without direct mixing, thereby meeting the temperature control needs of various industries. Examples include raw material preheating in the petrochemical industry and turbine exhaust steam condensation in the power industry. It is of great significance for ensuring the efficient and stable operation of industrial processes.

[0003] Currently, the most widely used heat exchangers in the industrial field mainly include two types: shell-and-tube heat exchangers and floating head heat exchangers. Shell-and-tube heat exchangers (also known as fixed tubesheet heat exchangers) consist of a shell, tube bundle, tube sheet, and end caps. The tube sheets at both ends of the tube bundle are rigidly connected to the shell, resulting in a relatively simple overall structure and lower manufacturing cost. They are suitable for applications where the fluid medium is clean and the temperature difference between the tube-side and shell-side fluids is small. Floating head heat exchangers, on the other hand, have structural improvements to address thermal expansion issues. The tube sheet at one end of the tube bundle is not fixed to the shell but is assembled with a floating head cover to form a freely movable floating head structure. Only the tube sheet at the other end is rigidly connected to the shell. This allows them to adapt to applications with a large temperature difference between the tube-side and shell-side fluids, and where the shell-side fluid contains impurities or is prone to scaling. Furthermore, they facilitate cleaning and maintenance of the outer surface of the tube bundle.

[0004] However, both types of traditional heat exchangers have significant drawbacks in practical applications. For shell-and-tube heat exchangers, because the tube bundle and shell are rigidly fixed, when the temperature difference between the tube-side and shell-side fluids is large, the tube bundle and shell will undergo significant thermal deformation due to the difference in their coefficients of thermal expansion. This leads to significant thermal stress at the connection points, which can easily cause tube sheet cracking, tube bundle seal failure, or even shell deformation over long-term operation. Even with the addition of expansion joints, the problem cannot be fundamentally solved, and it also increases the size and cost of the equipment. For floating head heat exchangers, the sealing structure between the floating head and the shell increases the flow resistance of the shell-side fluid, resulting in increased energy consumption. At the same time, its structure includes multiple precision components such as the floating head cover and seals, making it highly complex. This not only increases the manufacturing difficulty and cost but also makes cleaning the inner surface of the tube bundle inconvenient, requiring regular replacement of seals, resulting in short maintenance cycles and high costs. Utility Model Content

[0005] The purpose of this utility model is to provide a thermal stress compensation tube bundle heat exchange structure to solve the technical problems of traditional heat exchangers, such as poor temperature difference adaptability, unreliable sealing, large shell-side pressure loss, inconvenient maintenance, and insufficient optimization of the heat exchange process.

[0006] To achieve the above objectives, the specific technical solution of the thermal stress compensation tube bundle heat exchange structure of this utility model is as follows:

[0007] A thermal stress compensation tube bundle heat exchange structure includes a cylinder, fixed end caps and movable end caps disposed at both ends of the cylinder, and a plurality of heat exchange tubes disposed within the cylinder.

[0008] A first tube sheet is clamped between the fixed end cap and the cylinder. A second tube sheet is provided at the other end of the cylinder, matching the inner wall. A movable tube sheet skirt is provided extending outward from the second tube sheet. The extended end of the movable tube sheet skirt is connected to the movable end cap. An annular packing groove is formed along the inner wall of the cylinder corresponding to the second tube sheet. The packing groove and the outer peripheral end face of the second tube sheet enclose a packing space for placing packing.

[0009] A packing gland is provided on the outer surface of the movable tube sheet skirt connected to the second tube sheet. A packing protrusion is provided on the packing gland along the outer surface of the movable tube sheet skirt to the packing groove. The packing protrusion enters the packing groove and squeezes the packing. The packing fully abuts against the second tube sheet under the squeezing of the packing gland.

[0010] The shell body is provided with a shell-side inlet and a shell-side outlet for the shell-side medium to enter and exit. The fixed end cap is provided with a tube-side outlet, and the movable end cap is provided with a tube-side inlet. The two ends of the heat exchange tube pass through the first tube sheet and the second tube sheet respectively and are connected to the tube-side outlet and the tube-side inlet. The tube-side medium enters from the tube-side inlet, flows through the heat exchange tube and exchanges heat with the shell-side medium, and then exits from the tube-side outlet.

[0011] As a further improvement of this utility model, the outer diameter of the second tube sheet matches the inner diameter of the cylinder, and the movable tube sheet skirt extends along the outer radial direction of the second tube sheet to the outer side of the cylinder.

[0012] As a further improvement of this utility model, a loose flange is movably provided on the outer surface of the movable tube sheet skirt and the movable head connecting side, and a head flange is provided on the outer surface of the movable head and the movable tube sheet skirt connecting side, and the loose flange and the head flange are connected by bolts.

[0013] As a further improvement of this utility model, an annular connecting groove is provided on the outer surface of the movable tube sheet skirt near the movable head. A flange connecting groove is provided on the inner surface of the end of the loose flange facing the head flange, corresponding to the connecting groove. A connecting ring is provided in the connecting groove. The connecting ring protrudes relative to the outer surface of the movable tube sheet skirt. The protruding end of the connecting ring matches the flange connecting groove. The protruding end of the connecting ring enters the flange connecting groove to achieve a stable connection between the loose flange and the head flange.

[0014] As a further improvement of this utility model, a plurality of guide plates are provided inside the cylinder, and the guide plates are staggered inside the cylinder to increase the flow of the shell-side medium inside the cylinder.

[0015] As a further improvement of this utility model, the fixed end cap is connected to the cylinder body through a flange, and the first tube sheet is clamped and fixed between the fixed end cap and the cylinder body.

[0016] As a further improvement of this utility model, a connecting flange is provided on the outer side of the cylinder relative to the second tube sheet. After the packing protrusion enters the connecting groove, the connecting flange and the packing gland are fixed by bolts.

[0017] As a further improvement of this utility model, the filler is flexible graphite or polytetrafluoroethylene.

[0018] As a further improvement of this utility model, the tube-side medium is a coolant, and the shell-side medium is natural gas.

[0019] Beneficial effects:

[0020] In this invention, the second tube sheet matches the inner wall of the shell but is not rigidly fixed to the shell. Combined with the connection design of the movable tube sheet skirt and the movable head, the heat exchange tubes can move freely along the axial direction of the shell as a whole, along with the second tube sheet, the movable tube sheet skirt, and the movable head. When the temperature difference between the tube-side and shell-side fluids changes, the tube bundle can offset the thermal expansion difference through expansion and contraction, completely avoiding the thermal stress caused by rigid fixing in traditional shell-and-tube heat exchangers. No additional expansion joints are needed, simplifying the structure and preventing problems such as tube sheet cracking and sealing failure, significantly improving the equipment reliability and service life under large temperature difference conditions.

[0021] The recessed end of the shell forms a packing groove, which, together with the outer periphery of the second tube sheet, encloses the packing space. The packing gland, through packing protrusions, compresses the packing, allowing it to fully contact the second tube sheet under compression, creating a tight and stable seal that effectively prevents shell-side medium leakage. Compared to the complex sealing components of traditional floating head heat exchangers, this structure has no unnecessary obstructive parts, significantly reducing shell-side medium flow resistance, decreasing pressure loss, and thus reducing fluid transport energy consumption and improving operational economy.

[0022] The tube-side medium enters the heat exchange tubes through the tube-side inlet of the movable head, while the shell-side medium flows through the shell-side inlets and outlets on both sides of the shell. After efficient heat exchange between the two media through the tube walls, the tube-side medium exits from the tube-side outlet of the fixed head. This flow channel design ensures that the two media do not mix directly, and the heat exchange tubes provide sufficient contact area for heat transfer, enabling stable heat exchange. This design is suitable for the core requirements of fluid temperature control in industrial scenarios, especially for processes requiring precise control of media separation and heat exchange efficiency.

[0023] The structure, where the fixed head clamps and secures the first tube sheet to the shell, and the movable tube sheet skirt is directly connected to the movable head, clarifies the assembly logic of the core components (such as heat exchange tubes, tube sheets, and heads), eliminating the need for complex assembly components and reducing manufacturing and assembly difficulty. Furthermore, if basic inspections of the heat exchange tubes or sealing components are required later, the core components can be quickly accessed by disassembling the fixed or movable head. Compared to traditional heat exchangers, this reduces structural disassembly steps and facilitates routine maintenance. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of a thermal stress compensation tube bundle heat exchange structure according to the present invention;

[0025] Figure 2 A schematic diagram of the second tube sheet, movable tube sheet skirt, and movable head structure;

[0026] The markings in the diagram are as follows: 1. Shell; 11. Shell-side inlet; 12. Shell-side outlet; 13. Packing groove; 14. Connecting flange; 15. Baffle plate; 2. Fixed head; 21. Tube-side outlet; 3. Movable head; 31. Tube-side inlet; 32. Head flange; 4. First tube sheet; 5. Second tube sheet; 6. Movable tube sheet skirt; 61. Packing gland; 62. Packing bump; 63. Loose flange; 64. Connecting groove; 65. Flange connecting groove; 66. Connecting ring; 7. Heat exchange tube. Detailed Implementation

[0027] To enhance understanding of this utility model, the present utility model will be further described in detail below with reference to the embodiments and accompanying drawings. These embodiments are only used to explain the present utility model and do not constitute a limitation on the scope of protection of the present utility model.

[0028] Implementation example:

[0029] like Figure 1 and 2 The illustrated thermal stress-compensated tube bundle heat exchange structure includes a shell 1, a fixed end cap 2, a movable end cap 3, a first tube sheet 4, a second tube sheet 5, and heat exchange tubes 6. The shell 1 is a hollow carrier with shell-side inlets and outlets on its side walls. The fixed end cap 2 and movable end cap 3 have tube-side inlets and outlets. Heat exchange tubes 7 are fixed between the first tube sheet 4 and the second tube sheet 5, forming a tube-side channel. Cooling water flows through the tube side, entering from the tube-side inlet 31 of the movable end cap 3, flowing through the heat exchange tubes 7 to the tube-side outlet 21 of the fixed end cap 2. Natural gas to be cooled flows through the shell side, entering from the shell-side inlet 11 of the shell, flowing along the outer wall of the heat exchange tubes 7, and exiting from the shell-side outlet 12, forming a heat exchange path between the cooling water inside the tubes and the natural gas outside. Cooling water and natural gas transfer cooling through the heat exchange tube walls, and the heat of the natural gas is carried away by the cooling water, resulting in a temperature reduction.

[0030] The shell 1 is a cylindrical hollow shell with openings at both ends, made of corrosion-resistant metal, with a smooth inner wall to reduce natural gas flow resistance. Shell-side inlets 11 and outlets 12 are respectively opened on the side walls, forming a bottom-in, top-out path adapted to the flow characteristics of natural gas, avoiding gas-liquid stagnation. Flanges with sealing structures are installed at the interfaces for connecting external natural gas pipelines. As the carrier frame of the overall structure, its interior provides installation space for the heat exchange tubes 7 and guide plates 15, while also forming a flow channel for natural gas in the shell side, guiding the natural gas to fully contact the outer wall of the heat exchange tubes 7 to complete heat exchange. The guide plates 15 are arranged alternately up and down along the heat exchange tubes 7 inside the shell 1 to increase the flow path of natural gas within the shell.

[0031] Both the fixed head 2 and the movable head 3 are shells that are closed at one end and open at the other. They are made of corrosion-resistant metal, and the inner walls are smoothed to reduce cooling water flow resistance and scale buildup. The open ends are equipped with connection structures, and the closed ends have tube-side outlets 21 and 31, respectively. Connecting components are provided at the interfaces for easy connection to external cooling water pipelines. The fixed head 2 serves as the cooling water outlet chamber, ensuring that cooling water is discharged only from the tube-side outlet. The movable head 3 serves as the cooling water inlet chamber and can move synchronously with the expansion and contraction of the heat exchange tubes, preventing leakage along the cooling water flow path. The head flange 32 is an annular metal flange, fixedly connected to the open end of the movable head 3. Bolt holes and sealing grooves (for placing gaskets) are provided on the flange face, making it a key component for the detachable connection between the movable head 3 and the movable tube sheet skirt 6.

[0032] Both the first tube sheet 4 and the second tube sheet 5 are circular metal plates with uniformly spaced through holes matching the heat exchange tubes 7 for fixing both ends of the heat exchange tubes 7. The fixed end cap 2 and the cylinder 1 are connected by flanges. The first tube sheet 4 is clamped between the fixed end cap 2 and the cylinder 1. The edge of the second tube sheet 5 extends to form a movable tube sheet skirt 6, which can slide freely along the inner wall of the cylinder 1. As the core component for fixing and sealing the heat exchange tubes 7, the first tube sheet 4 fixes both ends of the heat exchange tubes 7, forming an independent cooling water flow channel. The first tube sheet 4 achieves a rigid seal at the cooling water outlet end, and the second tube sheet 5 can drive the heat exchange tubes 7 to extend and retract freely, avoiding thermal stress caused by temperature difference from damaging the equipment. At the same time, it forms a sealed space with the packing groove 13 to block natural gas leakage.

[0033] The movable tube sheet skirt 6 is an annular metal structure, welded to one side of the end face of the second tube sheet 5. Its outer surface is a smooth extension of the outer end face of the second tube sheet 5, and an annular connecting groove 64 is formed on the outer surface near the movable head 3. The movable tube sheet skirt 6 acts as a bridge connecting the second tube sheet 5 and the movable head 3, providing stable support for the movable head 3 and ensuring synchronous movement of the two. The connecting groove 64 is used to accommodate the connecting ring 66, which cooperates with the loose flange 63 to achieve precise docking between the movable tube sheet skirt 6 and the movable head 3. At the same time, it provides an installation reference for the packing gland 61, and works with the packing to achieve natural gas sealing, avoiding structural deformation caused by cooling water pressure. The packing groove 13 is an annular groove formed by the indentation of the inner wall of the cylinder 1 near the second tube sheet 5, which together with the outer peripheral end face of the second tube sheet 5 forms a packing space. The packing gland 61 is an annular metal block protruding from the surface of the movable tube sheet skirt 6. A packing protrusion 62 is provided on the side facing the packing groove 13, which can be embedded in the packing groove 13. As a packing clamping component, the packing protrusion 62 is pushed to squeeze the packing by fixing it to the cylinder connecting flange 14, so that the packing produces elastic deformation to enhance the sealing effect.

[0034] The loose flange 63 is an annular metal flange with an inner diameter that matches the outer diameter of the movable tube sheet skirt 6. A flange connection groove 65, matching the connecting groove 64 of the movable tube sheet skirt, is formed on the inner surface of the end facing the head flange 32. Through holes corresponding to the bolt holes of the head flange are evenly distributed on the flange face. Serving as the connection medium between the movable tube sheet skirt 6 and the movable head 3, the flange connection groove 65 matches the connecting ring 66 within the connecting groove 64 of the movable tube sheet skirt 6, ensuring coaxiality with the movable tube sheet skirt 6 and preventing misalignment of the sealing surface during connection. Simultaneously, it is fixed to the head flange 32 with bolts, enabling a detachable connection between the movable tube sheet skirt 6 and the movable head 3, facilitating the disassembly of the movable head 3 during subsequent maintenance.

[0035] The packing is made of a high-temperature resistant, corrosion resistant and elastic material. In this application, the packing is flexible graphite. Through the elastic deformation of the packing, it fits tightly with the second tube sheet 5 and the cylinder 1, adapts to the expansion and contraction of the second tube sheet 6, and always maintains the sealing performance. The packing fits with the outer peripheral end face of the second tube sheet 6, the inner wall of the packing groove 13 and the packing protrusion 62 of the packing gland 61 respectively to form a sealing system.

[0036] The heat exchange tube 7 is made of metal that is resistant to cooling water corrosion. The inner wall is smoothed to reduce water flow resistance and scale buildup, while the outer wall can be finned to increase the contact area with natural gas according to heat exchange requirements. As the core carrier for heat exchange between cooling water and natural gas, cooling water flows inside the tube, and natural gas flows outside. Heat is transferred through the tube wall to achieve natural gas temperature regulation. The fin design improves heat exchange efficiency, and the corrosion-resistant material ensures that cooling water does not leak into the shell side and mix with natural gas. The two ends of the heat exchange tube 7 are inserted into the through holes of the first tube sheet 4 and the second tube sheet 5, respectively, forming a tube bundle structure that runs through the shell. One end is connected to the tube-side outlet 21 of the fixed end cap 2, and the other end is connected to the tube-side inlet 31 of the movable end cap 3.

[0037] In operation, cooling water enters through the tube-side inlet 31 of the movable head 3, is evenly distributed to the interior of each heat exchange tube 7 through the chamber of the movable head 3, flows along the heat exchange tube 7 to the fixed head 2, and finally exits from the tube-side outlet 21, forming a stable flow path in the tube side. Natural gas enters through the shell-side inlet 11 of the cylinder 1, flows along the outer wall of the heat exchange tube 7 inside the cylinder 1, and is guided by the guide plate 15 to extend its flow path. After exchanging heat with the cooling water inside the tube through the tube wall, it exits from the shell-side outlet 12. When the temperature difference between the cooling water and natural gas causes the heat exchange tube 7 to expand and contract, the second tube sheet 5 drives the movable tube sheet skirt 6 and the movable head 3 to slide along the inner wall of the cylinder 1. During the expansion and contraction process, the packing is always tightly fitted to the second tube sheet 5, the packing groove 13 and the movable tube sheet skirt 6 under the pressure of the packing gland 61, maintaining the natural gas sealing effect.

[0038] This application demonstrates strong adaptability to temperature differences and mitigates the risk of thermal stress. Through the expandable design of the second tube sheet 5, movable tube sheet skirt 6, and movable end cap 3, the heat exchange tubes 7 can freely expand and contract with the medium temperature difference, eliminating the need for additional expansion joints. This completely solves the thermal stress problem caused by the rigid fixing of traditional shell-and-tube heat exchangers, preventing tube sheet cracking and seal failure, extending equipment life, and adapting to the conditions where natural gas cooling often involves large temperature differences. A triple elastic seal is formed through the packing groove 13, the packing, and the packing gland 61. The flexible packing remains in contact with the tube bundle as it expands and contracts, preventing natural gas leakage. The tube side achieves a double seal through the connection of the slip-on flange 63, the end cap flange 32, and the heat exchange tubes 7 to the tube sheet, preventing cooling water leakage or mixing with natural gas and ensuring safety. The loose flange 63 and the head flange 32 are detachable. The movable head can be separated by removing the bolts, which makes it easy to clean the scale inside the heat exchange tubes. The packing can be replaced by loosening the packing gland bolts without disassembling the whole unit. During reinstallation, the loose flange and the movable tube sheet skirt are easy to align, reducing maintenance time and downtime. The efficiency is better than that of traditional floating head heat exchangers.

[0039] It is understood that this utility model has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of this utility model. Furthermore, under the teachings of this utility model, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of this utility model. Therefore, this utility model is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of this utility model.

Claims

1. A thermal stress-compensating tube bundle heat exchange structure, characterized in that, It includes a cylindrical body, fixed end caps and movable end caps disposed at both ends of the cylindrical body, and a plurality of heat exchange tubes disposed inside the cylindrical body; A first tube sheet is clamped between the fixed end cap and the cylinder. A second tube sheet is provided at the other end of the cylinder, matching the inner wall. A movable tube sheet skirt is provided extending outward from the second tube sheet. The extended end of the movable tube sheet skirt is connected to the movable end cap. An annular packing groove is formed along the inner wall of the cylinder corresponding to the second tube sheet. The packing groove and the outer peripheral end face of the second tube sheet enclose a packing space for placing packing. A packing gland is provided on the outer surface of the movable tube sheet skirt connected to the second tube sheet. A packing protrusion is provided on the packing gland along the outer surface of the movable tube sheet skirt to the packing groove. The packing protrusion enters the packing groove and squeezes the packing. The packing fully abuts against the second tube sheet under the squeezing of the packing gland. The shell body is provided with a shell-side inlet and a shell-side outlet for the shell-side medium to enter and exit. The fixed end cap is provided with a tube-side outlet, and the movable end cap is provided with a tube-side inlet. The two ends of the heat exchange tube pass through the first tube sheet and the second tube sheet respectively and are connected to the tube-side outlet and the tube-side inlet. The tube-side medium enters from the tube-side inlet, flows through the heat exchange tube and exchanges heat with the shell-side medium, and then exits from the tube-side outlet.

2. The thermal stress compensation tube bundle heat exchange structure according to claim 1, characterized in that, The outer diameter of the second tube sheet matches the inner diameter of the cylinder, and the movable tube sheet skirt extends along the outer radial direction of the second tube sheet to the outside of the cylinder.

3. The thermal stress compensation tube bundle heat exchange structure according to claim 1 or 2, characterized in that, A loose flange is movably provided on the outer surface of the movable tube sheet skirt and the movable head connecting side, and a head flange is provided on the outer surface of the movable head and the movable tube sheet skirt connecting side, and the loose flange and the head flange are connected by bolts.

4. The thermal stress compensation tube bundle heat exchange structure according to claim 3, characterized in that, The movable tube sheet skirt has an annular connecting groove on its outer surface near the movable head. The inner surface of the end of the loose flange facing the head flange has a flange connecting groove corresponding to the connecting groove. A connecting ring is provided in the connecting groove. The connecting ring protrudes relative to the outer surface of the movable tube sheet skirt. The protruding end of the connecting ring matches the flange connecting groove. The protruding end of the connecting ring enters the flange connecting groove to achieve a stable connection between the loose flange and the head flange.

5. The thermal stress compensation tube bundle heat exchange structure according to claim 1, characterized in that, The cylinder is provided with a plurality of guide plates, which are staggered within the cylinder to increase the flow rate of the shell-side medium within the cylinder.

6. The thermal stress compensation tube bundle heat exchange structure according to claim 1, characterized in that, The fixed end cap is connected to the cylinder via a flange, and the first tube sheet is clamped and fixed between the fixed end cap and the cylinder.

7. The thermal stress compensation tube bundle heat exchange structure according to claim 4, characterized in that, A connecting flange is provided on the outer side of the cylinder relative to the second tube sheet. After the packing protrusion enters the connecting groove, the connecting flange and the packing gland are fixed by bolts.

8. The thermal stress compensation tube bundle heat exchange structure according to claim 1, characterized in that, The filler is flexible graphite or polytetrafluoroethylene.

9. The thermal stress compensation tube bundle heat exchange structure according to claim 1, characterized in that, The tube-side medium is a coolant, and the shell-side medium is natural gas.

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