Heat stress resistant flexible tube plate device and waste heat boiler

Abstract

The invention relates to the technical field of waste heat boilers, and particularly discloses a heat-stress-resistant flexible tube plate device and a waste heat boiler, the heat-stress-resistant flexible tube plate device comprises a variable-diameter connecting section coaxially connected with a tube box side and a shell side, and a thin plate sleeved in the variable-diameter connecting section and coaxially connected with the variable-diameter connecting section; the variable-diameter connecting section comprises a variable-diameter shell connected with the tube box at one end, and a connecting section connected with the variable-diameter shell, the thin plate and the shell respectively; the connecting section is connected with one side, far away from the tube box, of the variable-diameter shell and forms an annular groove coaxially communicated with the tube box; a heat preservation layer is arranged in the annular groove; the cross section of the annular groove is obliquely arranged; the small end of the annular groove is arranged on the side close to the tube box. The stress level is reduced, and the technical problems that in the prior art, the stress of the outer-layer heat exchange tube and the edge stress of the tube plate cannot be considered, and large temperature difference is difficult to deal with are solved.

Description

Technical Field

[0001] This invention relates to the field of waste heat boiler technology, and more specifically, to a heat-stress-resistant flexible tube sheet device and a waste heat boiler. Background Technology

[0002] Under the dual pressures of energy and environmental constraints, waste heat boilers (hereinafter referred to as waste boilers) play a vital role in numerous fields due to their efficient ability to recover industrial waste heat. Waste boilers convert waste heat from high-temperature waste gases and liquids into steam or hot water through heat exchange, which can then be used for power generation, heating, etc., achieving cascaded energy utilization, reducing energy consumption and pollution emissions, and saving costs and enhancing competitiveness for enterprises. In industries such as steel, cement, and chemicals, waste heat boilers can recover waste heat from blast furnace gas, kiln tail gas, and the processes of synthetic ammonia and ethylene cracking, ensuring production operations and reducing overall energy consumption.

[0003] Fire-tube waste heat boilers typically operate under conditions of high temperature and high pressure of the tube-side medium, and are characterized by large temperature differences between the tubes, high corrosion resistance requirements, and strong coupling between heat transfer and stress. Due to the significant inconsistency in thermal expansion between the heat exchange tubes and the shell, a fixed tube sheet would require a large thickness, impacting not only the economics of the equipment but also the flexibility and safety of components in handling complex operating conditions. A feasible solution is to adopt a flexible structure design for the tube sheet of the waste heat boiler. This design compensates for the difference in thermal expansion through elastic deformation, absorbing excess strain energy and thus reducing local stress levels. Furthermore, a thinner tube sheet is beneficial for handling unsteady heat transfer conditions. When temperature fluctuations occur on both sides of the tube sheet, a smaller thermal diffusion depth allows the tube sheet to reach a new thermal equilibrium more quickly, making transient thermal stress fluctuations in the tube sheet relatively controllable.

[0004] The mainstream structural designs of existing flexible tube sheets can be divided into two categories: Type I and Type II flexible tube sheets as specified in Appendix M of GB / T 151-2014. Both types of flexible tube sheets adopt rounded edge transitions to ensure that the elastic deformation of the tube sheet does not generate excessive concentrated stress at the connection between the tube sheet and the shell and tube box. Another approach involves reinforcing one side of the tube sheet edge, such as the Chinese patent with publication number CN213983518U entitled "Flexible Tube Sheet for Waste Heat Boiler," which discloses a design that reduces the localized stress on the outer heat exchange tubes caused by the flexible deformation of the tube sheet edge through edge reinforcement. This approach is suitable for processes with high shell-side pressure. In addition, there are technical solutions that involve setting up a separate cooling chamber on the shell side of the tube sheet and reinforcing it to eliminate thermal stress on the tube sheet and to enhance its rigidity. Examples include Chinese patents CN113137877A (published as "A Flexible Tube Sheet Structure for Coping with Tube-Shell Pressure Difference and Corresponding Waste Heat Boiler") and CN104791747B (published as "A Cooling Chamber for Tube Sheet of a High-Temperature Fire-Tube Waste Heat Boiler").

[0005] However, existing flexible tube sheet designs still have one or more of the following shortcomings: First, flexible tube sheets are typically thin and have poor rigidity, requiring the heat exchange tubes to provide sufficient support. Therefore, the thickness of waste heat boiler heat exchange tubes is usually much greater than that of conventional heat exchange tubes. Since the number of heat exchange tubes is usually very large, the total weight of the heat exchange tube system often becomes one of the main costs of waste heat boilers. A well-designed flexible tube sheet structure can theoretically reduce the requirements for supporting the heat exchange tubes, thereby significantly reducing costs. Currently, most common flexible tube sheets do not have optimized designs in this regard.

[0006] Secondly, the outermost heat exchange tubes are supported by other heat exchange tubes inside, but have no heat exchange tubes on the outside and are close to the shell tube sheet connection area, resulting in a discontinuous structure and asymmetrical stress. Therefore, the opening area where the outer heat exchange tubes connect to the tube sheet often experiences greater concentrated stress, which is one of the core constraints on reducing the thickness of the heat exchange tubes. The detachment of the outer heat exchange tubes from the tube sheet weld is one of the most common structural failures in the actual production process of waste heat boilers.

[0007] In addition, the tube box of the waste heat boiler uses an internal insulation structure, with a temperature close to ambient temperature, while the shell uses an external insulation structure, with a temperature close to the saturation temperature of the high-pressure steam on the shell side. The tube box and shell are located on both sides of the flexible tube sheet and welded to the edge of the tube sheet. The large temperature difference will generate significant thermal stress on both sides of the flexible tube sheet edge, requiring reinforcement of other components of the waste heat boiler. Especially in inland areas with severe winters, traditional flexible tube sheet waste heat boilers place higher demands on project site selection, civil engineering, and other external conditions, significantly increasing project costs.

[0008] Finally, while incorporating a cooling chamber inside the flexible tubesheet can effectively eliminate the dead zone near the shell-side end face of the tubesheet, the heat exchange tubes in this area often have protective insulation material inside to protect the welded structure of the tubesheet-heat exchange tubes. Therefore, increasing the heat transfer coefficient in this area has minimal effect on improving the overall heat exchange capacity of the waste heat boiler. Furthermore, adding unnecessary support plates and tie rods to the flexible tubesheet may severely weaken its fatigue resistance, and the heat exchange tube support structure used to seal the chamber may restrict the free bending deformation of the heat exchange tubes, increasing local stress in the tubes.

[0009] In summary, due to the inherent contradictions between the flexibility of the tube sheet, the support of the heat exchange tubes, the stress on the outer heat exchange tubes, and the stress on the edge of the tube sheet, the existing flexible tube sheet structure design is difficult to balance all aspects of performance. Its application scope is often limited to scenarios with low and medium steam pressure and mild operating environment, and its application range is very limited.

[0010] Therefore, a new type of flexible tube sheet design is needed. This design can not only meet the strength requirements under extreme working conditions (such as cold environments or the requirement to generate high-pressure steam), but also has a longer fatigue life, better adjustability, and wider applicability, thereby meeting the technical requirements of waste heat boiler equipment for safe, stable, and efficient operation. Summary of the Invention

[0011] The technical problem to be solved by this invention is to provide a heat-stress-resistant flexible tube sheet device and waste heat boiler, which reduces the corresponding stress level and solves the technical difficulties of existing technologies that cannot simultaneously address the stress of the outer heat exchange tubes and the edge stress of the tube sheet, and are unable to cope with large temperature differences. The solution adopted by this invention to solve the technical problem is: on the one hand: A heat-resistant stress flexible tube sheet device is provided between a tube box and a shell, including a variable diameter connecting section coaxially connected to the tube box side and the shell side, and a thin plate fitted inside the variable diameter connecting section and coaxially connected. The variable diameter connecting section includes a variable diameter outer shell connected to a pipe box at one end, and connecting sections that are respectively connected to the variable diameter outer shell, the thin plate, and the shell. The connecting section is connected to the side of the variable diameter outer shell away from the pipe box and forms an annular groove that is coaxially connected with the pipe box; an insulation layer is provided in the annular groove. The cross-section of the annular groove is inclined; the small end of the annular groove is located on the side closer to the pipe box.

[0012] In some possible implementations, the connecting section includes a cylindrical straight section that is coaxially connected to the end of the variable diameter outer shell away from the tube box and the shell side, and an annular section that is coaxially fitted inside the cylindrical section and is funnel-shaped; the thin plate is coaxially fitted inside the annular section.

[0013] In some possible implementations, the angle formed by the thin plate and the annular segment is... , ; The smaller end of the variable diameter outer shell is connected to the pipe box, and the radial angle formed between the variable diameter outer shell and the pipe box is... , .

[0014] In some possible implementations, an isolation cover is also included, which is disposed on the side of the housing near the annular segment and is connected and cooperates with the annular segment, the housing and the connecting segment to form an isolation zone; a gap is formed between the side of the isolation cover near the annular segment and the annular segment.

[0015] In some possible implementations, the isolation cover includes a connector mounted inside the housing and located directly above the central tube inside the housing, and an arc-shaped isolation plate connected to the connector, the center of the isolation plate being concentric with the center of the thin plate; The gap between the isolation plate and the annular segment is... , The isolation plate is inclined and forms an angle with the shell along the axial direction. , .

[0016] In some possible implementations, the angle formed by the two ends of the partition plate and the horizontal direction is... , The thickness of the isolation plate is , .

[0017] In some possible implementations, the isolation plate is coaxially arranged with the housing and has an inner diameter of [missing information]. The inner diameter of the annular segment is , .

[0018] In some possible embodiments, a central hole communicating with the tube box and connected to the central tube inside the shell is provided on the thin plate, the central hole being coaxially arranged with the thin plate, and heat exchange holes are also provided on the thin plate; the thickness of the thin plate is [missing information]. ; , This is the support radius of the heat exchanger tube.

[0019] on the other hand: A waste heat boiler includes a tube box, a shell, and a heat-resistant stress-resistant flexible tube sheet device for connecting the tube box and the shell as described above; the tube box, the heat-resistant stress-resistant flexible tube sheet device, and the shell are coaxially connected; a heat exchange tube communicating with heat exchange holes is provided inside the shell.

[0020] In some possible implementations, the inner diameter of the pipe box is The thickness of the side wall of the pipe box is The inner diameter of the shell is The thickness of the shell sidewall is ; Insulation material is provided on the inner wall of the pipe box, and the thickness of the insulation material is [missing information]. , , is the inner diameter of the annular segment.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention optimizes and controls the propagation path of internal forces along various components of the equipment by setting up variable diameter connecting sections, thin plates, and isolation covers, and balances the stress levels at the front-end tube box welding points and heat exchange tube welding points, thereby improving the overall strength of the equipment. The present invention reduces the diameter of the tube box by setting a variable diameter outer shell and a straight section, thereby reducing the area of ​​the unsupported region of the outer heat exchange tube, thus reducing the asymmetry of the local stress on the heat exchange tube and reducing its bending stress and flexural deformation. By setting an isolation cover in the shell side near the edge of the tube sheet, the strong natural convection of the fluid medium boiling at that location is isolated, reducing the temperature difference between the local tube sheet and the front tube box, thereby reducing the local thermal stress level. This invention strengthens the outer heat exchange tubes by reducing the inner diameter of the tube box, thereby reducing the required thickness of the heat exchange tubes to a certain extent and significantly improving the economic efficiency of the equipment. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the waste heat boiler in this invention; Figure 2 This is a schematic diagram of the heat-stress-resistant flexible tube sheet device in this invention; Figure 3 This is a side view of the heat-resistant stress-resistant flexible tube sheet device in this invention; Figure 4 This is a partially enlarged view of the heat-resistant stress-resistant flexible tube sheet device in this invention; Figure 5 This is a schematic diagram of the structure when the variable diameter connection section is not used in the existing calculations, and a schematic diagram of the structure connected to the pipe box and shell. Figure 6 This is a schematic diagram of fluid flow when no isolation shield is used in this invention; Figure 7 This is a schematic diagram of fluid flow when an isolation shield is used in this invention; The components are: 1. Front-end tube box; 2. Variable diameter connection section; 21. Variable diameter outer shell; 22. Straight section; 23. Annular section; 24. Annular groove; 3. Thin plate; 31. Heat exchange hole; 32. Central hole; 33. Central docking section; 4. Isolation cover; 5. Shell; 6. Heat-resistant stress flexible tube sheet device; 7. Rear-end tube box. Detailed Implementation

[0023] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. The terms "first," "second," and similar terms used in this application do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, "a" or "one," etc., do not indicate a quantity limitation, but rather indicate the existence of at least one. In the implementation of this application, "and / or" describes the association relationship of related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. In the description of the embodiments of this application, unless otherwise stated, "multiple" means two or more. For example, multiple positioning posts refer to two or more positioning posts. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0024] The present invention will now be described in detail.

[0025] Example 1: like Figures 1-7 As shown, a heat-resistant stress flexible tube sheet device is provided between the tube box and the shell 5, including a variable diameter connecting section 2 coaxially connected to the tube box side and the shell 5 side, and a thin plate 3 fitted inside the variable diameter connecting section 2 and coaxially connected. The variable diameter connecting section 2 includes a variable diameter outer shell 21 connected to a pipe box at one end, and connecting sections connected to the variable diameter outer shell 21, the thin plate 3, and the shell 5 respectively. The variable diameter outer shell 21 is frustoconical in shape, with its small end inner diameter being the same as the inner diameter of the pipe box, and its large end being connected to the connecting section. The outer diameter of the connecting section is the same as the outer diameter of the shell 5. The connecting section is connected to the side of the variable diameter outer shell 21 away from the pipe box and forms an annular groove 24 coaxially connected to the pipe box; an insulation layer is provided in the annular groove 24; the connecting section includes a cylindrical straight section 22 coaxially connected to the side of the variable diameter outer shell 21 away from the pipe box and in the shape of a cylinder, and an annular section 23 coaxially fitted inside the straight section 22 and in the shape of a trumpet; the thin plate 3 is coaxially fitted inside the annular section 23 and cooperates with the annular section 23 to form a tube sheet; the thin plate 3 and the annular section 23 can be processed by welding or integral molding. The cross-section of the annular groove 24 is inclined; the small end of the annular groove 24 is located on the side close to the pipe box; The inner diameter of the straight section 22 is the same as the inner diameter of the shell 5 and they are connected to each other. The annular section 23 is connected to the straight section 22 and cooperates with the variable diameter shell 21 and the straight section 22 to form an annular groove 24. The cross-section of the annular groove 24 is U-shaped and inclined, and its opening side is connected to the inside of the tube box. The annular groove 24, the tube box, the straight section 22, and the variable diameter shell 21 are coaxially arranged. The present invention forms an annular groove 24 by the cooperation of the variable diameter shell 21 and the annular segment 23. When thermal expansion difference occurs, torque is generated on both sides of the variable diameter shell 21, and the bending stress in this area is reduced by the torsion of the variable diameter shell 21. Furthermore, reverse prestress is applied to the tube sheet through shot peening and other means to balance the secondary stress caused by thermal expansion differences; By setting an insulation layer in the annular groove 24, the heat conduction distance of the welding end face is increased, the local temperature gradient is reduced, and the local thermal stress is reduced. At the same time, the structural discontinuity of the pipe box (welding position) is separated from the position with large temperature gradient (the diameter change area of ​​the variable diameter shell 21), reducing the risk of stress concentration.

[0026] In some possible implementations, the angle formed by the thin plate 3 and the annular segment 23 is... , ; The smaller end of the variable diameter outer shell 21 is connected to the pipe box, and the radial angle formed by the variable diameter outer shell 21 and the pipe box is [value missing]. , .

[0027] In some possible implementations, such as Figure 6 As shown, the steam generated by boiling outside the tube may condense at the connection between the annular section 23 and the straight section 22, resulting in a higher local temperature at that location. This increases the local temperature difference and thermal stress on both sides of the weld between the tube sheet and the tube box. To address this issue, the heat-resistant flexible tube sheet device 6 also includes an isolation cover 4 disposed on the side of the shell 5 near the annular section 23 and connected to the annular section 23, the shell 5, and the connecting section to form an isolation zone. A gap is formed between the isolation cover 4 and the annular section 23 on the side near the annular section 23. The isolation cover 4 includes a connector installed inside the housing 5 and located directly above the central tube inside the housing 5, and an isolation plate connected to the connector and in an arc shape, wherein the center of the isolation plate is concentric with the center of the thin plate 3; The gap between the isolation plate and the annular segment 23 is... , The isolation plate is inclined and forms an angle with the housing 5 along the axial direction. , .

[0028] like Figure 7 As shown, by setting up the isolation cover 4, the fluid at the variable diameter outer shell 21 is isolated from the bubbles generated by evaporation at the heat exchange tubes inside the shell 5 and the strong convective fluid, greatly reducing the risk of boiling bubbles condensing at the variable diameter outer shell 21. At this time, the convective heat transfer coefficient of the variable diameter outer shell 21 is significantly reduced, and the temperature of the variable diameter outer shell 21 decreases accordingly. Its main heat transfer path changes from direct contact with the shell-side fluid to the path from the shell-side fluid through the thin plate 3 to the variable diameter outer shell 21, or from the shell-side fluid through the isolation cover 4 to the variable diameter outer shell 21, or from the shell-side fluid through the shell 5 to the variable diameter outer shell 21. In addition, by reducing the diameter of the tube box, the thermal displacement of the tube box can be effectively reduced, and its deflection deformation can be reduced; correspondingly, the bending stress caused by the uneven local thermal expansion of the tube box is reduced.

[0029] In some possible implementations, in order to effectively achieve the inclined arrangement of the annular segment 23, the angle formed by the two ends of the isolation plate and the horizontal direction is . That is, the angle formed by the projection of the isolation plate onto the two ends of the plane containing the thin plate 3 and the horizontal plane is . , The thickness of the isolation plate is , .

[0030] In some possible implementations, the isolation plate is coaxially arranged with the housing 5 and has an inner diameter of [missing information]. The inner diameter of the annular segment 23 is , .

[0031] In some possible embodiments, a central hole 32 is provided on the thin plate 3, which communicates with the tube box and is connected to the central tube inside the shell 5. The central hole 32 is coaxially arranged with the thin plate 3. Heat exchange holes 31 are also provided on the thin plate 3. The thickness of the thin plate 3 is... ; , This is the support radius of the heat exchanger tube.

[0032] This invention optimizes the force transmission path within the flexible tube sheet through geometric structural parameter design, achieving a rational distribution of the tube sheet material's load-bearing capacity and mitigating the impact of thermal effects. For example... Figure 6 , Figure 7 As shown, a schematic diagram comparing the insulation and thermal deformation of the flexible tube sheet under typical working conditions is given. Since the tube box adopts an insulation structure with an internal insulation lining, its temperature is close to the ambient temperature, and radial shrinkage occurs under cold conditions such as winter. The flexible tube sheet and shell 5 are in direct contact with high-pressure water vapor, and the water and steam are in a state of intense boiling heat transfer. Therefore, the technical temperature of the tube sheet and shell 5 is close to the steam temperature, and radial expansion occurs.

[0033] like Figure 5As shown, when the variable diameter connecting section 2 is not used, the shell 5 and the tube box end are directly connected through the tube sheet. There is a large area of ​​thermal expansion mismatch at the connection, which generates a large local temperature difference stress. The structural discontinuity area and the thinner shell wall area of ​​common waste heat boilers are usually located here. Therefore, a large local stress is superimposed at this point.

[0034] like Figure 4 As shown, when the variable diameter connecting section 2 is designed, due to the presence of the annular groove 24, when thermal expansion difference occurs, torque is generated on both sides of the variable diameter connecting section 2, and the bending stress in this area is reduced by the torsion of the variable diameter connecting section 2.

[0035] This invention adds a variable diameter connecting section 2 and an isolation cover 4 to the heat exchanger shell 5, so that the fluid at the connection between the outer edge of the flexible tube sheet and the tube box and shell 5 is in a relatively static state and does not participate in the intense boiling convective heat transfer inside, thereby forming a relatively heat-insulating zone in a local area. The convective heat transfer coefficient in this area can be significantly reduced, so that the local temperature of the flexible tube sheet device is lower than the tube box temperature, and the corresponding thermal stress of the tube sheet and tube box is eliminated to a certain extent. On the other hand, the variable diameter outer shell 21 radially misaligns the welding end face of the tube box with the welding end face of the shell 5, thereby reducing the unsupported area of ​​the outer heat exchange tube, strengthening the outermost heat exchange tube, and reducing the flexible deformation of the outer heat exchange tube and the local stress between it and the tube hole.

[0036] Example 2: like Figures 1-4 , Figure 7 As shown, a waste heat boiler includes a tube box, a shell 5, and a heat-resistant stress-resistant flexible tube sheet device 6 for connecting the tube box and the shell 5 as described in Embodiment 1; the tube box, the heat-resistant stress-resistant flexible tube sheet device 6, and the shell 5 are coaxially connected; a heat exchange tube communicating with a heat exchange hole 31 is provided inside the shell 5; the tube box includes a front tube box 1 and a rear tube box 7; the heat-resistant stress-resistant flexible tube sheet device 6 consists of two sets; one set is located between the front tube box 1 and the shell 5, with the small end of the variable diameter shell 21 connected to the front tube box 1; the other set is located between the rear tube box 7 and the shell 5, with the small end of the variable diameter shell 21 connected to the rear tube box 7; The heat exchange tube includes an outer heat exchange tube and an inner heat exchange tube, with the inner heat exchange tube disposed between the central tube and the outer heat exchange tube; a central docking section 33 coaxial with the central hole 32 is provided on the side of the thin plate 3 near the shell 5.

[0037] In some possible implementations, the inner diameter of the pipe box is The thickness of the side wall of the pipe box is The inner diameter of the housing 5 is The thickness of the five side walls of the shell is ; Insulation material is provided on the inner wall of the pipe box, and the thickness of the insulation material is [missing information]. , , It is the inner diameter of the annular segment 23.

[0038] Example 3: like Figure 1 As shown, taking a waste heat boiler in a methanation system as an example, the waste heat boiler is designed using the Type II flexible tube sheet specified in Appendix M of the national standard GB / T 151-2014, the flexible tube sheet in publication number CN213983518U, and the heat-resistant stress flexible tube sheet device of this invention. Specifically, the syngas temperature of this waste heat boiler is approximately 600 degrees Celsius, with a pressure of approximately 4 MPa, a steam-side pressure of 12 MPa, and an ambient temperature of 20 degrees Celsius. The waste heat boiler uses an NXN type heat exchanger as specified in GB / T 151-2014, and employs a flexible tube sheet design. The center thickness of the tube sheet is uniformly 35 mm, and the wall thickness of the heat exchange tubes (outer heat exchange tube and inner heat exchange layer) is 4.5 mm. The insulation measures are the same, and the heat exchange tubes (outer heat exchange tube and inner heat exchange layer) do not penetrate the heat exchange hole 31. The allowable stress of the tube sheet material is 186 MPa, and the maximum allowable stress value is 444 MPa according to the linearization evaluation of GB / T 4732.3~4 including secondary stress. At this time, stress linearization analysis is performed on the normal direction of the tube box connection area, the normal direction of the welding area of ​​the heat exchange hole 31, and the tube sheet thickness direction using different designs, and the relevant dimensions are selected within the recommended range.

[0039] The linearization paths are divided into three categories: path one, path two, and path three. For each type of linearization path, multiple paths are taken near the corresponding region and the maximum value of the linearization result is selected. Path one is the thickness direction at the tube box connection, path two is the depth direction of the outer heat exchange tube hole in the tube sheet near the front tube box 1, and path three is the depth direction of the outer heat exchange tube hole in the tube sheet near the rear tube box 7. The analysis results are shown in Table 1. The Type II flexible tube sheet specified in Appendix M of GB / T 151-2014 and the patent CN213983518U both failed the evaluation, while the present invention can meet the evaluation requirements on the selected linearization path.

[0040]

[0041] Table 1 This invention can reduce the diameter of the tube box while improving the stress conditions, significantly saving the amount of material required for the tube box. On the other hand, it significantly improves the stress level in the welding area between the outer heat exchange tubes and the tube sheet, reducing the required thickness of the heat exchange tubes (outer and inner layers), thus greatly reducing the amount of material needed. For example, for a medium to large-sized waste heat boiler with a diameter of 3m and a tube length of 8m (outer and inner layers), reducing the diameter of the tube box and thinning the tube sheet can save approximately 8% to 12% of the tube box weight. While the thickness of the outermost heat exchange tube remains unchanged, the thickness of the central tube can be reduced by 10%, resulting in a weight saving of approximately 5% to 8% for the heat exchange tubes (outer and inner layers). Approximately 10 tons of stainless steel material can be saved, demonstrating a significant cost reduction effect.

[0042] This invention spatially repositions the local welding areas at the edge of the tube sheet by setting a variable-diameter outer shell 21. This introduces new parts and new welding areas, and also accommodates structural shapes that are difficult to process in practice, such as deep grooves or concave structures, thus keeping manufacturing costs comparable to existing conventional tube sheets. The reduced tube wall thickness allows for the arrangement of more heat exchange tubes within the same tube arrangement circle constraint, resulting in shorter equipment length, lower overall material costs, and reduced floor space costs, leading to significant economic benefits.

[0043] This invention is not limited to the specific embodiments described above. The invention extends to any new feature or combination disclosed in this specification, as well as any new method or process step or combination disclosed herein.

Claims

1. A heat-stress-resistant flexible tube sheet device, disposed between a tube box and a shell, characterized in that, It includes a variable diameter connecting section that is coaxially connected to the tube box side and the shell side, and a thin plate that is fitted inside the variable diameter connecting section and coaxially connected; The variable diameter connecting section includes a variable diameter outer shell connected to a pipe box at one end, and connecting sections that are respectively connected to the variable diameter outer shell, the thin plate, and the shell. The connecting section is connected to the side of the variable diameter outer shell away from the pipe box and forms an annular groove that is coaxially connected with the pipe box; an insulation layer is provided in the annular groove. The cross-section of the annular groove is inclined; the small end of the annular groove is located on the side closer to the pipe box.

2. The heat-stress-resistant flexible tube sheet device according to claim 1, characterized in that, The connecting section includes a cylindrical straight section that is coaxially connected to the end of the variable diameter outer shell away from the pipe box and the shell side, and an annular section that is coaxially fitted inside the cylindrical section and is funnel-shaped; the thin plate is coaxially fitted inside the annular section.

3. The heat-stress-resistant flexible tube sheet device according to claim 2, characterized in that, The angle formed by the thin plate and the annular segment is , ; The smaller end of the variable diameter outer shell is connected to the pipe box, and the radial angle formed between the variable diameter outer shell and the pipe box is... , .

4. The heat-stress-resistant flexible tube sheet device according to claim 3, characterized in that, It also includes an isolation cover disposed on the side of the housing near the annular segment and connected and cooperated with the annular segment, the housing and the connecting segment to form an isolation zone; a gap is formed between the side of the isolation cover near the annular segment and the annular segment.

5. The heat-stress-resistant flexible tube sheet device according to claim 4, characterized in that, The isolation cover includes a connector installed inside the housing and located directly above the central tube inside the housing, and an arc-shaped isolation plate connected to the connector, wherein the center of the isolation plate is concentric with the center of the thin plate; The gap between the isolation plate and the annular segment is... , The isolation plate is inclined and forms an angle with the shell along the axial direction. , .

6. The heat-stress-resistant flexible tube sheet device according to claim 5, characterized in that, The angle formed by the two ends of the isolation plate and the horizontal direction is: , The thickness of the isolation plate is , .

7. The heat-stress-resistant flexible tube sheet device according to claim 5, characterized in that, The isolation plate is coaxially arranged with the shell and has an inner diameter of [missing information]. The inner diameter of the annular segment is , .

8. The heat-stress-resistant flexible tube sheet device according to claim 1, characterized in that, A central hole communicating with the tube box and connected to the central tube inside the shell is provided on the thin plate. The central hole is coaxially arranged with the thin plate. Heat exchange holes are also provided on the thin plate. The thickness of the thin plate is [missing information]. ; , This is the support radius of the heat exchanger tube.

9. A waste heat boiler, characterized in that, It includes a tube box, a shell, and a heat-resistant stress-resistant flexible tube sheet device for connecting the tube box and the shell as described in any one of claims 1-8; the tube box, the heat-resistant stress-resistant flexible tube sheet device, and the shell are coaxially connected; a heat exchange tube communicating with heat exchange holes is provided inside the shell.

10. A waste heat boiler according to claim 9, characterized in that, The inner diameter of the pipe box is The thickness of the side wall of the pipe box is The inner diameter of the shell is The thickness of the shell sidewall is ; ; Thermal insulation material is provided on the inner wall of the pipe box, and the thickness of the thermal insulation material is [missing information]. , , is the inner diameter of the annular segment.

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