High-pressure-resistant heat exchanger and welding method thereof

Abstract

The invention belongs to the technical field of heat exchange equipment, and particularly relates to a high-pressure-resistant heat exchanger and a welding method thereof.The heat exchanger comprises a shell with the gradient wall thickness, a reinforcing rib end socket, a tube plate, a fall type tube pass channel and a temperature and pressure self-adaption integrated ring, a composite pressure bearing structure is arranged on the outer wall of the fall type tube pass channel, and the reinforcing rib end socket is provided with a cold source pipeline and a heat source pipeline; through the synergistic effect of all the components, the problems that an existing heat exchanger is insufficient in pressure bearing capacity, prone to leakage, prone to freezing and blocking and poor in sealing performance under the working conditions of high pressure and temperature and pressure fluctuation are solved, the operation stability of equipment is improved, and the service life of the equipment is prolonged; according to the welding method, through layered and staged precise welding and stress control, the connection reliability of all parts is ensured, and the high-pressure resistance of equipment is further enhanced.

Description

Technical Field

[0001] This invention belongs to the technical field of heat exchange equipment, specifically relating to a high-pressure resistant heat exchanger and its welding method. Background Technology

[0002] As the core equipment for heat transfer in industrial production, heat exchangers are widely used in many fields such as petroleum, chemical, energy, and metallurgy. Especially in high-pressure conditions (such as high-pressure hydrogenation and high-pressure heat exchange systems), extremely high requirements are placed on the equipment's pressure-bearing capacity, sealing performance, temperature and pressure adaptability, and anti-freezing and anti-blocking capabilities.

[0003] Currently, existing heat exchangers have many shortcomings in their high-pressure resistance design. A detailed analysis of existing technologies reveals the following: One existing high-pressure heat exchanger improves its performance through hemispherical heads, bamboo-like biomimetic heat dissipation tubes, and electron beam welding. However, it lacks a composite pressure-bearing structure and relies solely on the expansion and contraction of the heat dissipation tubes to distribute the load. This makes it difficult to handle concentrated loads under high-pressure conditions. Furthermore, it lacks temperature and pressure adaptive regulation and anti-freezing design, making it prone to sealing failure during temperature and pressure fluctuations and freezing blockage under low-temperature conditions. Another existing technology discloses a high-temperature, high-pressure corrosion-resistant composite heat exchanger, which achieves high-pressure corrosion resistance through composite materials and a split-shell structure. However, the split-shell structure is complex and costly to manufacture, and it also lacks a temperature and pressure adaptive structure and anti-freezing design. Its heat exchange efficiency is not effectively optimized. These technologies fail to address the technical challenges of complex conditions such as high pressure and low temperature.

[0004] In summary, existing heat exchangers with certain high-pressure resistance employ uniform wall thickness shells and fixed support structures, making them ill-suited to adapt to dynamic changes in pressure and temperature. They also lack effective adaptive pressure relief and anti-freeze protection mechanisms, resulting in insufficient reliability under extreme operating conditions. Therefore, there is an urgent need for a heat exchanger structure capable of adapting to high pressure and temperature variations, and possessing anti-freeze and anti-blockage functions, along with a corresponding reliable welding process. Summary of the Invention

[0005] In view of the above-mentioned shortcomings in the existing technology, the purpose of this invention is to provide a high-pressure resistant heat exchanger and its welding method, so as to solve the problems of easy deformation, easy freezing and blockage, and lack of adaptive pressure relief capability of existing heat exchangers under high pressure and large temperature difference conditions.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a high-pressure resistant heat exchanger and its welding method, comprising a gradient wall thickness shell, reinforcing ribs detachably connected to both ends of the gradient wall thickness shell, a tube sheet disposed within the gradient wall thickness shell and cooperating with the corresponding reinforcing ribs to seal, a drop-type tube-side channel disposed on the tube sheet, and a temperature and pressure adaptive integrated ring disposed between the reinforcing ribs and the gradient wall thickness shell. The outer wall of the drop-type tube-side channel is provided with a composite pressure-bearing structure, which includes an axial inner rib, a variable stiffness support unit, an adaptive pressure relief unit, and a spiral baffle. The top and bottom of the reinforcing ribs on both sides are respectively provided with a cold source inlet pipe and a cold source outlet pipe for cold source flow. The top and bottom between the reinforcing ribs and the temperature and pressure adaptive integrated ring are also provided with a heat source inlet pipe and a heat source outlet pipe for heat source flow. An anti-freezing blockage structure is also provided between the gradient wall thickness shell and the drop-type tube-side channel.

[0007] Furthermore, the wall thickness of the gradient wall thickness shell decreases linearly from both ends to the middle region, and the inner wall of the gradient wall thickness shell has annular grooves evenly distributed along the circumference, with elastic pads and temperature sensors provided in the annular grooves.

[0008] Furthermore, the tube sheet includes a base layer, a stress buffer layer and a corrosion-resistant layer connected in sequence. The tube sheet is provided with several interfaces, and the reinforcing rib end cap is provided with a wedge block connected to the interface. A temperature sensor is provided inside the wedge block.

[0009] Furthermore, the temperature and pressure adaptive integrated ring includes an outer ring, an inner ring, a temperature and pressure compensation block, and an elastic element. The outer ring is fixedly connected to the gradient wall thickness shell, the inner ring is provided with a wedge-shaped inclined surface, the outer wall of the elastic element is fixedly connected to the temperature and pressure compensation block, and the temperature and pressure compensation block is engaged and fixed with the wedge-shaped inclined surface.

[0010] Furthermore, the variable stiffness support unit is a shape memory alloy tube disposed on the inner wall of the axial inner rib and wrapping the drop-type tube channel, and the adaptive pressure relief unit is a pressure relief pipe disposed on the outer wall of the shape memory alloy tube, the pressure relief pipe is connected to a pressure relief valve, and the pressure relief valve is connected to the gradient wall thickness shell.

[0011] Furthermore, the drop-type pipe channel includes a horizontal section, a falling section, and an insulation section arranged along the flow direction of the cold source. The falling sections are arranged to cross each other, the horizontal section is connected to the cold source inlet pipe, and the end of the insulation section is connected to the cold source outlet pipe.

[0012] Furthermore, the antifreeze structure includes an antifreeze pipe disposed on the outer wall of the shape memory alloy tube and connected to the heat source inlet pipe, the antifreeze pipe is filled with heat-conducting oil, and a control valve is provided at the connection between the antifreeze pipe and the heat source inlet pipe.

[0013] It also includes a high-pressure heat exchanger welding method, comprising the following steps: S1: Composite pressure-bearing structure layered welding: The elastic gasket and temperature sensor are pre-installed in the annular groove of the gradient wall thickness shell. The axial inner rib and the inner wall of the shell are welded in layers by argon arc welding. After the first layer of root welding, the fit is confirmed by ultrasonic monitoring. During the second layer of fill welding, the welding temperature is controlled synchronously with the temperature sensor to avoid thermal deformation of the elastic gasket. The shape memory alloy tube is sleeved on the outside of the drop-type tube passage. The axial inner rib and the shape memory alloy tube are fixed by laser spot welding. Then, the spiral baffle and the axial inner rib are symmetrically welded in segments along the circumference. Finally, the pressure relief pipe is assembled and connected to the shape memory alloy tube and the pressure relief valve by brazing. S2: Stress-directed welding of tube sheet and shell: After the base layer, stress buffer layer and corrosion-resistant layer of tube sheet are compositely formed, the tube sheet is connected to the gradient wall thickness shell by electron beam welding. During welding, the outer circumferential seam of the tube sheet is welded first, and then the connection point between the tube sheet and the axial inner rib is welded. At the same time, the wedge block of the reinforcing rib head is positioned through the tapered interface of the tube sheet, and the assembly gap is reserved. S3: Temperature and pressure adaptive integrated ring dual-stage welding: First, the outer ring of the temperature and pressure adaptive integrated ring is welded and fixed to the gradient wall thickness shell. Then, the inner ring, temperature and pressure compensation block and elastic element are positioned by wedge-shaped inclined surface. Laser root pass welding is used to fix the axial gap between the inner ring and the outer ring. Finally, the outer ring and the reinforcing rib end cap are alternately welded along the circumference. During the welding process, the welding current is adjusted by the deformation feedback of the temperature and pressure compensation block to ensure the sealing and fitting accuracy. S4: Antifreeze plugging structure co-welding: The antifreeze pipe is attached to the outer wall of the shape memory alloy pipe according to the preset path. The antifreeze pipe and the shape memory alloy pipe are welded in sections by pulse argon arc welding. When welding the connection between the heat source inlet pipe and the antifreeze pipe, the control valve is pre-installed and the adjustment space is reserved. Then, the connection is sealed by brazing. S5: Integrated stress relief and sealing verification: The entire equipment is placed in an annealing furnace for segmented stress relief annealing. During the heating stage, the temperature of the welding area is monitored simultaneously by a temperature sensor. During the heat preservation stage, ultrasonic scanning is used to detect internal defects in the weld. After annealing, the medium is introduced through the cold source inlet pipe and the heat source inlet pipe respectively to test the linkage sealing performance of the pressure relief valve and the control valve and the weld leakage.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. High structural strength and uniform stress distribution: The wall thickness of the gradient wall thickness shell decreases from both ends to the middle. Combined with the support of axial inner ribs and helical baffles, this results in a more uniform stress distribution under high pressure, avoiding deformation or cracking caused by localized stress concentration. The elastic gasket in the annular groove further absorbs the minor deformation of the shell caused by temperature and pressure changes, improving the overall pressure resistance stability.

[0015] 2. Strong adaptability to temperature and pressure changes: The temperature and pressure adaptive integrated ring automatically adjusts the gap when temperature or pressure changes through the cooperation of the inner ring wedge-shaped inclined surface and the temperature and pressure compensation block, compensating for dimensional changes caused by thermal expansion and contraction and preventing seal failure. The shape memory alloy tube, as a variable stiffness support unit, can change its own stiffness according to temperature, further adapting to fluctuations in operating conditions.

[0016] 3. Integrated pressure relief and anti-freeze functions: The adaptive pressure relief unit, linked to the pressure relief valve via a pressure relief pipe, automatically releases the medium when the system is overpressured, ensuring safe operation. The anti-freeze structure utilizes the residual heat in the heat source inlet pipe, circulating heat transfer oil within the anti-freeze pipe to prevent freezing and blockage of the drop-type pipe passage in low-temperature environments, thus improving the equipment's applicability in cold regions.

[0017] 4. High heat exchange efficiency and low flow resistance: The drop-type tube channel adopts a cross-fall section design, which extends the flow path of the cold medium, enhances the turbulence effect, and improves the heat exchange efficiency. The spiral baffle guides the spiral flow of the hot medium, prolongs the heat exchange time, and at the same time avoids medium short circuit and reduces flow resistance.

[0018] 5. In the composite pressure-bearing structure of the present invention, the axial inner ribs disperse the radial pressure of the tube side, the shape memory alloy tube (variable stiffness support unit) adaptively adjusts its stiffness to adapt to temperature and pressure changes, the pressure relief pipe and pressure relief valve (adaptive pressure relief unit) realize automatic pressure relief when the pressure exceeds the standard, and the spiral baffle not only helps to disperse the load, but also changes the flow direction of the heat source and enhances heat exchange. The synergistic effect of each component greatly improves the overall high pressure resistance of the equipment, avoids damage to the tube side channel, and at the same time takes into account the heat exchange efficiency.

[0019] 6. Existing heat exchangers cannot compensate for the relative deformation of their components when temperature and pressure fluctuate, which can easily lead to problems such as increased sealing gaps and media leakage. The temperature and pressure adaptive integrated ring of this invention adaptively compensates for the component deformation caused by temperature and pressure fluctuations through the relative displacement of the temperature and pressure compensation block and the wedge-shaped inclined surface of the inner ring, as well as the deformation of the elastic element. This effectively avoids sealing failure and ensures the stable operation of the equipment under temperature and pressure fluctuation conditions. 7. The anti-freezing structure of this invention uses heat transfer oil inside the anti-freezing pipe to transfer heat from the heat source, and links the temperature sensor and control valve to achieve adaptive adjustment, which can effectively prevent the pipe medium from freezing and blocking under low temperature conditions, and ensure the stable operation of the equipment under low temperature and high pressure conditions. Attached Figure Description

[0020] Figure 1 This paper shows an overall schematic diagram of a high-pressure resistant heat exchanger according to an embodiment of this application; Figure 2 This paper shows an overall schematic diagram of the reinforcing rib end cap of a high-pressure resistant heat exchanger according to an embodiment of this application; Figure 3A schematic diagram of a tube sheet for a high-pressure resistant heat exchanger according to an embodiment of this application is shown; Figure 4 This paper shows an overall schematic diagram of a temperature and pressure adaptive integrated ring for a high-pressure heat exchanger according to an embodiment of this application; Figure 5 This paper shows an overall schematic diagram of a variable stiffness support unit for a high-pressure heat exchanger according to an embodiment of this application. Figure 6 The diagram illustrates the welding steps of a high-pressure heat exchanger welding method according to an embodiment of this application.

[0021] The reference numerals in the accompanying drawings include: 1. Gradient wall thickness shell; 2. Baffle plate; 3. Annular groove; 4. Tube sheet; 5. Base layer; 6. Stress buffer layer; 7. Corrosion resistant layer; 8. Temperature and pressure adaptive integrated ring; 9. Cold source inlet pipe; 10. Cold source outlet pipe; 11. Drop-type tube passage; 12. Drop section; 13. Insulation section; 14. Annular groove; 15. Antifreeze pipe; 16. Heat source inlet pipe; 17. Heat source outlet pipe; 18. Reinforcing rib end cap; 19. Interface; 10. Wedge block; 11. Shape memory alloy tube; 12. Pressure relief pipe; 13. Inner ring; 14. Elastic element; 15. Outer ring; 16. Temperature sensor. Detailed Implementation

[0022] To further illustrate the technical means and effects adopted by the present invention in order to achieve the intended purpose, the following detailed description is provided in conjunction with the accompanying drawings and preferred embodiments, based on the specific implementation methods, structures, features and effects of the present invention.

[0023] Example 1: like Figure 1-5As shown, a high-pressure resistant heat exchanger of the present invention includes a gradient wall thickness shell 1, a reinforcing rib head 13, a tube sheet 4, a drop-type tube-side channel 8, and a temperature and pressure adaptive integrated ring 5. The outer wall of the drop-type tube-side channel 8 is provided with a composite pressure-bearing structure, and the reinforcing rib head 13 is provided with cold source and heat source pipes. An anti-freezing and blockage structure is provided between the gradient wall thickness shell 1 and the drop-type tube-side channel 8. The heat exchanger has a symmetrical structure, and the core components are all assembled around the gradient wall thickness shell 1 to ensure balanced stress under high-pressure conditions. The gradient wall thickness shell 1, as the core load-bearing component of the equipment, has a wall thickness that decreases linearly from both ends to the middle region. This structural design can specifically disperse high-pressure loads—because the stress at the connection between the two ends of the gradient wall thickness shell 1 and the reinforcing rib head 13 is the greatest during equipment operation, the thicker wall thickness at both ends can effectively resist high-pressure impacts, while the decreasing wall thickness in the middle region can reduce the overall weight of the equipment and reduce manufacturing costs while ensuring pressure bearing capacity. On the inner wall of the gradient wall thickness shell 1, several annular grooves 3 are evenly distributed circumferentially. Each annular groove 3 is fitted with an elastic gasket and a temperature sensor 19. The elastic gasket fits tightly against the inner wall of the annular groove 3 and the subsequent composite pressure-bearing structure, which can not only help buffer the radial stress under high pressure, but also improve the sealing performance inside the shell and prevent the leakage of heat source medium inside the shell. The temperature sensor 19 monitors the temperature change of the inner wall of the gradient wall thickness shell 1 in real time, providing signal support for subsequent temperature and pressure regulation and anti-freezing control.

[0024] At both ends of the gradient wall thickness shell 1, reinforcing rib end caps 13 are detachably connected via flanges. These reinforcing rib end caps 13 are used to seal the end openings of the gradient wall thickness shell 1 and provide support for the installation of cold and heat source pipelines. The integrated reinforcing rib structure further enhances the pressure-bearing capacity of the end caps, preventing deformation under high-pressure conditions. Inside the gradient wall thickness shell 1, tube sheets 4 are installed at both ends. The tube sheets 4 cooperate with the corresponding reinforcing rib end caps 13 to achieve a sealed interior of the gradient wall thickness shell 1, preventing leakage of the mixed cold and heat source media. The tube sheet 4 adopts a composite layer structure, consisting of a base layer 401, a stress buffer layer 402, and a corrosion-resistant layer 403 connected sequentially. The base layer 401 serves as the load-bearing foundation, ensuring the structural strength of the tube sheet 4; the stress buffer layer 402 effectively absorbs residual stress generated during welding and working stress during equipment operation, preventing cracking of the tube sheet 4 due to stress concentration; and the corrosion-resistant layer 403 resists corrosion from cold and heat source media, extending the service life of the tube sheet 4. The tube sheet 4 is provided with several interfaces 14. Correspondingly, the reinforcing rib end cap 13 is provided with wedge blocks 1401 that match these interfaces 14. The wedge blocks 1401 are precisely engaged with the interfaces 14 to achieve positioning and fixation of the tube sheet 4 and the reinforcing rib end cap 13, while further improving the sealing performance between the two. The wedge blocks 1401 are also provided with temperature sensors 19, which cooperate with the temperature sensors 19 on the inner wall of the shell to achieve all-round monitoring of the internal temperature of the equipment.

[0025] Between the reinforcing rib head 13 and the gradient wall thickness shell 1, a temperature and pressure adaptive integrated ring 5 is also provided. The temperature and pressure adaptive integrated ring 5 is the core component for realizing temperature and pressure adaptation of the equipment. It is used to compensate for the relative deformation between various components when temperature and pressure fluctuate, and to ensure sealing performance. The temperature and pressure adaptive integrated ring 5 consists of an outer ring 18, an inner ring 17, a temperature and pressure compensation block, and an elastic element 1701. The outer ring 18 is fixedly connected to the outer wall of the end of the gradient wall thickness shell 1 to ensure the overall positioning of the temperature and pressure adaptive integrated ring 5. The inner ring 17 is tightly fitted to the inner wall of the reinforcing rib head 13. The inner side of the inner ring 17 is provided with a wedge-shaped inclined surface. The outer wall of the elastic element 1701 is fixedly connected to the temperature and pressure compensation block. The temperature and pressure compensation block is engaged and fixed with the wedge-shaped inclined surface of the inner ring 17 to form an adaptively adjustable connection structure. When temperature or pressure fluctuations occur during equipment operation, the gradient wall thickness shell 1, the reinforcing rib end cap 13, and the tube sheet 4 will undergo slight thermal expansion and contraction or deformation. At this time, the temperature and pressure compensation block will undergo relative displacement along the wedge-shaped inclined surface of the inner ring 17, and the elastic element 1701 will undergo elastic deformation accordingly. Through this displacement and deformation compensation, the relative deformation between the components is offset, the sealing gap is prevented from increasing, thereby preventing media leakage and ensuring the stable operation of the equipment under temperature and pressure fluctuation conditions.

[0026] A drop-type tube-side channel 8 is fixedly installed on the tube sheet 4. The drop-type tube-side channel 8 is the core channel for the flow of cold source medium. Its structural design ensures smooth flow of cold source and improves heat transfer efficiency. The drop-type tube-side channel 8 is provided with a horizontal section, a falling section 801 and an insulation section 802 in sequence along the flow direction of cold source. The horizontal section is connected to the cold source inlet pipe 6 at the top of the reinforcing head 13. The cold source medium enters the horizontal section through the cold source inlet pipe 6 and then flows into the falling section 801. The falling sections 801 are arranged in a cross pattern. This cross structure can prolong the residence time of the cold source medium in the tube, increase the heat exchange area between the cold source and the heat source, and improve the heat transfer efficiency. The insulation section 802 is connected to the cold source outlet pipe 7 at the bottom of the reinforcing head 13. After heat exchange, the cold source medium flows into the cold source outlet pipe 7 through the insulation section 802 and is discharged outside the equipment. The setting of the insulation section 802 can reduce the heat loss of the cold source medium during the outflow process and ensure heat exchange efficiency.

[0027] The outer wall of the drop-type tube-side channel 8 is wrapped with a composite pressure-bearing structure. This structure enhances the pressure-bearing capacity of the drop-type tube-side channel 8, disperses high-pressure loads, protects the tube-side channel from high-pressure damage, and also helps improve heat exchange efficiency. The composite pressure-bearing structure includes axial inner ribs, variable stiffness support units, adaptive pressure relief units, and spiral baffles 2. The axial inner ribs are arranged along the length of the drop-type tube-side channel 8 and are evenly distributed on the outer wall of the channel. The outer wall of the axial inner ribs is tightly fitted with the inner wall of the gradient wall thickness shell 1, which can effectively disperse the radial high-pressure load on the drop-type tube-side channel 8 and transfer the load to the gradient wall thickness shell 1, thus achieving uniform load distribution.

[0028] The variable stiffness support unit is a shape memory alloy tube 15, which is sleeved on the inner wall of the axial inner rib and wraps around the drop-type tube passage 8. Shape memory alloys have the characteristic of adaptively adjusting stiffness with temperature changes. When the operating temperature or pressure of the equipment changes, the shape memory alloy tube 15 automatically adjusts its own stiffness to adapt to load changes, providing stable support for the drop-type tube passage 8 and avoiding local stress concentration caused by fixed stiffness, further protecting the drop-type tube passage 8. The adaptive pressure relief unit is a pressure relief pipe 16, which is fixedly installed on the outer wall of the shape memory alloy tube 15. One end of the pressure relief pipe 16 is connected to the inside of the shape memory alloy tube 15, and the other end is connected to a pressure relief valve. The pressure relief valve is connected to the inside of the gradient wall thickness shell 1, forming a complete pressure relief circuit. When the internal pressure of the drop-type tube passage 8 exceeds the limit, the excess pressure will be transmitted to the pressure relief valve through the pressure relief pipe 16. The pressure relief valve will automatically open, releasing the excess pressure into the shell side of the gradient wall thickness shell 1, achieving pressure balance and preventing damage to the drop-type tube passage 8 due to excessive pressure, thus ensuring safe operation of the equipment. The spiral baffle 2 is fixedly installed on the outer wall of the axial inner rib and is evenly distributed along the circumference of the gradient wall thickness shell 1. The spiral baffle 2 can not only further disperse the high pressure load transmitted by the axial inner rib, but also change the flow direction of the heat source medium in the shell side, making the heat source medium flow in a spiral shape, avoiding medium short circuit, increasing the heat exchange time between the heat source and the cold source, and enhancing heat transfer efficiency.

[0029] In the region between the reinforcing rib head 13 and the temperature and pressure adaptive integrated ring 5, a shell-side space for the flow of the heat source medium is formed. Correspondingly, a heat source inlet pipe 11 is provided at the top between the reinforcing rib head 13 and the temperature and pressure adaptive integrated ring 5, and a heat source outlet pipe 12 is provided at the bottom. The heat source medium enters the shell-side space through the heat source inlet pipe 11 and, guided by the spiral baffle 2, flows spirally along the axial direction of the gradient wall thickness shell 1, exchanging heat with the cold source medium in the drop-type tube-side channel 8. After the heat exchange is completed, the heat source medium is discharged outside the equipment through the heat source outlet pipe 12. The cold source medium and the heat source medium flow in the tube side and shell side respectively, and heat transfer is achieved through the tube wall of the drop-type tube-side channel 8, completing the heat exchange process.

[0030] To prevent the cold source medium in the drop-type tube-side channel 8 from freezing and blocking the tube-side channel under low-temperature conditions, an anti-freezing structure is provided between the gradient wall thickness shell 1 and the drop-type tube-side channel 8. The anti-freezing structure includes an anti-freezing tube 10, which is tightly fitted to the outer wall of the shape memory alloy tube 15 and is arranged along the length of the drop-type tube-side channel 8. The anti-freezing tube 10 is filled with heat-conducting oil, which has good thermal conductivity and insulation properties. One end of the anti-freezing tube 10 is connected to the heat source inlet pipe 11. At the connection between the anti-freezing tube 10 and the heat source inlet pipe 11, a control valve is provided. The control valve is electrically connected to the temperature sensor 19 and can adaptively adjust according to the temperature signal. When the temperature sensor 19 detects that the internal temperature of the equipment is too low and there is a risk of freezing blockage, the control valve automatically opens, and the high-temperature heat source medium in the heat source inlet pipe 11 flows into the antifreeze pipe 10, heating the heat transfer oil in the antifreeze pipe 10. The heat transfer oil transfers heat to the shape memory alloy pipe 15 and the drop-type tube-side channel 8, insulating the cold source medium in the tube side and preventing freezing blockage. When the temperature rises back to a safe range, the control valve automatically closes, stopping the supply of heat source medium, realizing adaptive control of antifreeze blockage, which not only ensures the antifreeze effect but also avoids energy waste.

[0031] The high-pressure resistant heat exchanger of this invention achieves multiple benefits—high pressure resistance, temperature and pressure adaptation, freeze-blocking prevention, and efficient heat exchange—through the precise connection and synergistic effect of its components. The components work together and support each other, overcoming many shortcomings of existing heat exchangers under high-pressure conditions. Specifically, the gradient wall thickness shell 1 and the composite pressure-bearing structure work together to enhance the overall pressure-bearing capacity of the equipment; the temperature and pressure adaptive integrated ring 5, in conjunction with the temperature sensor 19 and the control valve, enables adaptive adjustment of temperature and pressure fluctuations and freeze-blocking control, ensuring reliable sealing; the drop-type tube-side channel 8, in conjunction with the spiral baffle 2, improves heat exchange efficiency. The design of all components revolves around the core requirements of high pressure resistance and stable operation, ensuring long-term stable operation of the equipment under complex conditions such as high pressure, temperature and pressure fluctuations, and low temperatures.

[0032] like Figure 6 As shown, the present invention also provides a high-pressure resistant heat exchanger welding method, applied to the aforementioned high-pressure resistant heat exchanger. Through layered, staged, precise welding and stress control, the reliability of the connection of each component is ensured, further enhancing the high-pressure resistance performance of the equipment. The specific welding process is as follows: First, the composite pressure-bearing structure is welded in layers. The elastic gasket and temperature sensor 19 are pre-installed in the annular groove 3 of the gradient wall thickness shell 1, ensuring a tight fit between the elastic gasket and the inner wall of the annular groove 3. The temperature sensor 19 is precisely positioned and firmly fixed to prevent displacement during welding. Then, argon arc welding is used to weld the axial inner rib to the inner wall of the gradient wall thickness shell 1 in layers. Argon arc welding is characterized by small welding deformation and high weld quality, making it suitable for welding high-pressure equipment. The first layer is a root pass weld. After the root pass weld is completed, ultrasonic testing is used to check the weld fit, ensuring that there are no defects such as incomplete penetration or porosity, and that the fit meets design requirements. The second layer is a filler weld. During the filler weld, the welding temperature is controlled synchronously and linked with the temperature sensor 19 in the annular groove 3. Welding parameters are adjusted in real time based on the signal from the temperature sensor 19 to prevent excessive welding temperature from causing thermal deformation of the elastic gasket and affecting subsequent sealing performance. After the filler welding is completed, the shape memory alloy tube 15 is fitted onto the outside of the drop-type tube-side channel 8, ensuring that the shape memory alloy tube 15 is tightly fitted to the outer wall of the drop-type tube-side channel 8. Then, the axial inner rib and the shape memory alloy tube 15 are fixed by laser spot welding. Laser spot welding is precise in positioning and the weld points are small, which can avoid affecting the performance of the shape memory alloy tube 15. After spot welding, the spiral baffle 2 and the axial inner rib are symmetrically welded in segments along the circumference. Segmental symmetrical welding can effectively disperse welding stress, avoid local stress concentration, and ensure that the spiral baffle 2 and the axial inner rib are firmly connected. Finally, the pressure relief pipe 16 is assembled, and the pressure relief pipe 16 is connected to the shape memory alloy tube 15 and the pressure relief valve by brazing. The brazed weld has good sealing performance, which can ensure that there is no leakage in the pressure relief circuit.

[0033] Next, stress-directed welding is performed between the tube sheet 4 and the shell. First, the base layer 401, stress buffer layer 402, and corrosion-resistant layer 403 of the tube sheet 4 are connected into one piece using an explosive composite forming process. Explosive composite forming ensures a tight connection between each layer, eliminating delamination defects and guaranteeing the composite layer structure performance of the tube sheet 4. After composite forming, the tube sheet 4 is butt-welded to the gradient wall thickness shell 1 using electron beam welding. Electron beam welding has high welding strength and good weld quality, making it suitable for welding thick-walled components of high-pressure equipment. During welding, the circumferential seam of the outer periphery of the tube sheet 4 is welded first. After the circumferential seam is welded, the connection point between the tube sheet 4 and the axial inner rib is welded. During the welding process, stress-directed welding is used, and the wedge-shaped block 1401 of the reinforcing rib head 13 is positioned simultaneously through the tapered interface 14 on the tube sheet 4, leaving a reasonable assembly gap to reserve space for the subsequent assembly of the temperature and pressure adaptive integrated ring 5 and temperature and pressure compensation. At the same time, it further disperses the welding stress and prevents cracking at the connection between the tube sheet 4 and the shell.

[0034] Then, the temperature and pressure adaptive integrated ring 5 is welded in two stages. In the first stage, the outer ring 18 of the temperature and pressure adaptive integrated ring 5 is welded and fixed to the gradient wall thickness shell 1 using argon arc welding to ensure that the outer ring 18 is firmly connected to the shell and accurately positioned. In the second stage, the inner ring 17, the temperature and pressure compensation block and the elastic element 1701 are assembled according to the design requirements, so that the temperature and pressure compensation block and the wedge-shaped inclined surface of the inner ring 17 are precisely engaged and positioned. Then, laser root pass welding is used to fix the axial gap between the inner ring 17 and the outer ring 18 to ensure that the relative position between the inner ring 17 and the outer ring 18 is fixed and to avoid welding deformation. After the root pass welding is completed, the outer ring 18 and the reinforcing rib head 13 are alternately welded along the circumference. Alternating welding can effectively disperse welding stress and avoid component deformation caused by excessive local temperature. During the welding process, the welding current is adjusted in real time through the deformation feedback of the temperature and pressure compensation block to ensure the sealing and fitting accuracy of the weld and to ensure the adjustment performance of the temperature and pressure adaptive integrated ring 5.

[0035] Next, the antifreeze plugging structure is welded together. The antifreeze tube 10 is tightly attached to the outer wall of the shape memory alloy tube 15 according to the preset path to ensure a tight fit between the antifreeze tube 10 and the shape memory alloy tube 15, which facilitates heat transfer. The antifreeze tube 10 and the shape memory alloy tube 15 are welded in sections using pulsed argon arc welding. Pulsed argon arc welding can effectively control the welding heat input and avoid damage to the shape memory alloy tube 15 and the antifreeze tube 10 due to excessive welding temperature. When welding the connection between the heat source inlet pipe 11 and the antifreeze tube 10, a control valve is pre-installed and a reasonable adjustment space is reserved to ensure that the control valve can be flexibly adjusted later. Then, the connection is sealed by brazing to ensure that there is no leakage at the connection and to ensure the working reliability of the antifreeze plugging structure.

[0036] Finally, integrated stress relief and sealing verification were performed. The welded equipment was placed in an annealing furnace for segmented stress relief annealing. Segmented annealing gradually eliminates residual stress generated during welding, preventing deformation or cracking during equipment operation. During the heating phase, the temperature of the welding area was monitored simultaneously by various temperature sensors 19, and the annealing temperature was adjusted in real time to ensure the annealing effect. During the heat preservation phase, ultrasonic scanning technology was used to detect internal defects in the welds, ensuring that all welds were free of defects such as incomplete penetration, porosity, and cracks, and that the weld quality met the design requirements. After annealing, the corresponding media were introduced through the cold source inlet pipe 6 and the heat source inlet pipe 11 to simulate the actual operating conditions of the equipment. The linkage sealing performance of the pressure relief valve and the control valve, as well as the leakage of all welds, were tested to ensure that the pressure relief valve could open normally to relieve pressure when the pressure exceeded the limit, the control valve could flexibly adjust according to the temperature signal, all welds were leak-free, and the equipment's sealing performance and operational reliability met the requirements. The welding work was then completed.

[0037] The above are merely embodiments of the present invention. The circuits, electronic components, and modules involved are all prior art, fully achievable by those skilled in the art, and require no further explanation. The content protected by this application does not involve improvements to the software and methods. Commonly known structures and characteristics in the solutions are not described in detail here. Those skilled in the art are aware of all common technical knowledge in the field prior to the application date or priority date, are able to access all prior art in that field, and have the ability to apply conventional experimental methods prior to that date. Those skilled in the art can, under the guidance of this application, improve and implement this solution in combination with their own capabilities. Some typical known structures or methods should not be obstacles for those skilled in the art to implement this application. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of the present invention. These should also be considered within the scope of protection of the present invention, and will not affect the effectiveness of the implementation of the present invention or the practicality of the application.

Claims

1. A high-pressure resistant heat exchanger, characterized in that: The device includes a gradient wall thickness shell, reinforcing ribs detachably connected to both ends of the gradient wall thickness shell, a tube sheet located inside the gradient wall thickness shell and sealing with corresponding reinforcing ribs, a drop-type tube-side channel on the tube sheet, and a temperature and pressure adaptive integrated ring located between the reinforcing ribs and the gradient wall thickness shell. The outer wall of the drop-type tube-side channel is provided with a composite pressure-bearing structure, which includes an axial inner rib, a variable stiffness support unit, an adaptive pressure relief unit, and a spiral baffle. The top and bottom of the reinforcing ribs on both sides are respectively provided with cold source inlet and cold source outlet pipes for cold source flow. The top and bottom between the reinforcing ribs and the temperature and pressure adaptive integrated ring are also provided with heat source inlet and heat source outlet pipes for heat source flow. An anti-freezing blockage structure is also provided between the gradient wall thickness shell and the drop-type tube-side channel.

2. A high-pressure resistant heat exchanger as described in claim 1, characterized in that: The wall thickness of the gradient wall thickness shell decreases linearly from both ends to the middle region. The inner wall of the gradient wall thickness shell has annular grooves evenly distributed along the circumference, and elastic pads and temperature sensors are provided in the annular grooves.

3. A high-pressure resistant heat exchanger as described in claim 1, characterized in that: The tube sheet includes a base layer, a stress buffer layer and a corrosion-resistant layer connected in sequence. The tube sheet is provided with several interfaces, and the reinforcing rib end cap is provided with a wedge block connected to the interface. A temperature sensor is provided inside the wedge block.

4. A high-pressure resistant heat exchanger as described in claim 3, characterized in that: The temperature and pressure adaptive integrated ring includes an outer ring, an inner ring, a temperature and pressure compensation block, and an elastic element. The outer ring is fixedly connected to the gradient wall thickness shell, the inner ring is provided with a wedge-shaped inclined surface, the outer wall of the elastic element is fixedly connected to the temperature and pressure compensation block, and the temperature and pressure compensation block is engaged and fixed with the wedge-shaped inclined surface.

5. A high-pressure resistant heat exchanger as described in claim 1, characterized in that: The variable stiffness support unit is a shape memory alloy tube located on the inner wall of the axial inner rib and enclosing the drop-type tube channel. The adaptive pressure relief unit is a pressure relief pipe located on the outer wall of the shape memory alloy tube. The pressure relief pipe is connected to a pressure relief valve, which is connected to the gradient wall thickness shell.

6. A high-pressure resistant heat exchanger as described in claim 1, characterized in that: The drop-type pipe channel includes a horizontal section, a falling section, and an insulation section arranged along the flow direction of the cold source. The falling sections are arranged to cross each other, the horizontal section is connected to the cold source inlet pipe, and the end of the insulation section is connected to the cold source outlet pipe.

7. A high-pressure resistant heat exchanger as described in claim 1, characterized in that: The antifreeze structure includes an antifreeze pipe located on the outer wall of the shape memory alloy tube and connected to the heat source inlet pipe. The antifreeze pipe contains heat-conducting oil, and a control valve is provided at the connection between the antifreeze pipe and the heat source inlet pipe.

8. A welding method for a high-pressure resistant heat exchanger, applied to the high-pressure resistant heat exchanger according to any one of claims 1-7, characterized in that, Includes the following steps: S1: Composite pressure-bearing structure layered welding: The elastic gasket and temperature sensor are pre-installed in the annular groove of the gradient wall thickness shell. The axial inner rib and the inner wall of the shell are welded in layers by argon arc welding. After the first layer of root welding, the fit is confirmed by ultrasonic monitoring. During the second layer of fill welding, the welding temperature is controlled synchronously with the temperature sensor to avoid thermal deformation of the elastic gasket. The shape memory alloy tube is sleeved on the outside of the drop-type tube passage. The axial inner rib and the shape memory alloy tube are fixed by laser spot welding. Then, the spiral baffle and the axial inner rib are symmetrically welded in segments along the circumference. Finally, the pressure relief pipe is assembled and connected to the shape memory alloy tube and the pressure relief valve by brazing. S2: Stress-directed welding of tube sheet and shell: After the base layer, stress buffer layer and corrosion-resistant layer of tube sheet are formed by explosive composite molding, the tube sheet is connected to the gradient wall thickness shell by electron beam welding. During welding, the outer circumferential seam of the tube sheet is welded first, and then the connection point between the tube sheet and the axial inner rib is welded. At the same time, the wedge block of the reinforcing rib head is positioned through the tapered interface of the tube sheet, and the assembly gap is reserved. S3: Temperature and pressure adaptive integrated ring dual-stage welding: First, the outer ring of the temperature and pressure adaptive integrated ring is welded and fixed to the gradient wall thickness shell. Then, the inner ring, temperature and pressure compensation block and elastic element are positioned by wedge-shaped inclined surface. Laser root pass welding is used to fix the axial gap between the inner ring and the outer ring. Finally, the outer ring and the reinforcing rib end cap are alternately welded along the circumference. During the welding process, the welding current is adjusted by the deformation feedback of the temperature and pressure compensation block to ensure the sealing and fitting accuracy. S4: Antifreeze plugging structure co-welding: The antifreeze pipe is attached to the outer wall of the shape memory alloy pipe according to the preset path. The antifreeze pipe and the shape memory alloy pipe are welded in sections by pulse argon arc welding. When welding the connection between the heat source inlet pipe and the antifreeze pipe, the control valve is pre-installed and the adjustment space is reserved. Then, the connection is sealed by brazing. S5: Integrated stress relief and sealing verification: The entire equipment is placed in an annealing furnace for segmented stress relief annealing. During the heating stage, the temperature of the welding area is monitored simultaneously by a temperature sensor. During the heat preservation stage, ultrasonic scanning is used to detect internal defects in the weld. After annealing, the medium is introduced through the cold source inlet pipe and the heat source inlet pipe respectively to test the linkage sealing performance of the pressure relief valve and the control valve and the weld leakage.

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