A flexible tube sheet structure for coping with shell-and-tube pressure difference and corresponding waste heat boiler

Abstract

The present invention relates to the technical field of heat exchange equipment, and specifically to a flexible tube sheet structure for coping with a shell-and-tube pressure difference and a corresponding waste heat boiler, comprising an inlet tube box, an outlet tube box, and a shell-and-tube cylinder. The flexible tube sheet structure comprises a thin tube sheet and a plurality of support plates arranged in parallel, each support plate comprising a plate body and a plurality of tie rods. The thin tube sheet has a plurality of rows of support holes, and a plurality of tie rods are inserted into the corresponding rows of support holes and fixed by countersunk welding. A plurality of reinforcing plates are welded and fixed to each two adjacent support plates. The invention also comprises a retaining ring for limiting the position of the support plates. Compared with the existing technology of densely welding a plurality of tie rods separately, the present invention can arrange and weld each support plate, reducing the manufacturing difficulty. Each row of tie rods is connected into one piece by the plate body, which has a higher overall strength and provides a more effective reinforcement effect for the thin tube sheet. The axial channel of the shell-and-tube space is not blocked by the thick tube sheet, thereby increasing the axial flow rate of cooling water in the shell and improving the heat exchange effect.

Description

Technical Field

[0001] The present invention relates to the technical field of heat exchange equipment used in the fields of petroleum refining, chemical industry, coal chemical industry, and more particularly to a flexible tube sheet structure for coping with shell-and-tube pressure difference and a corresponding waste heat boiler. Background Art

[0002] In fields such as petroleum refining and chemical engineering, coal chemical industry, and others, research on energy-saving technologies is increasing. Heat exchangers are the most widely used and widely used equipment for heat recovery. The junction between the tube sheet and the heat transfer tubes is the core and most vulnerable part of the heat exchanger. A large number of heat exchanger failures occur in this area. Waste heat boilers are a common type of heat exchanger.

[0003] Due to the thickness of traditional tubesheets, heat transfer is slow, temperature gradients are large, and stress concentration is a detrimental factor to equipment operation. This can easily damage the connection between the heat exchange tubes and the tubesheet, making it a major weak point in the heat exchanger. Excessively thick tubesheets also create excessive gaps between the tube holes and the heat exchange tubes, allowing salts to concentrate and scale in these gaps, leading to scaling corrosion. Under high-temperature conditions, thick tubesheet heat exchangers struggle to maintain long-term operation.

[0004] The use of thin tubesheets effectively reduces the temperature difference between the tubesheets, effectively preventing damage to the joints between the heat exchange tubes and the tubesheets, as well as equipment failure caused by tubesheet cracking. However, in large, high-pressure, and high-temperature environments, especially those with large pressure differences between the shell and tube, thin tubesheet waste heat boilers can experience significant deformation of the tubesheets due to the shell-to-tube pressure difference, which can easily lead to failure of the joints between the tubesheets and the heat exchange tubes.

[0005] As a result, the inventors proposed a technology with Chinese patent number CN201720412001.6, entitled "A Double-Tubesheet Combined Rapid Cooling Boiler for Coal Chemical Industry." This technology combines thin tubesheets with thick tubesheets, which are fixed together by dense tension welding. The thin tubesheets can absorb some thermal expansion due to their elastic deformation, and they conduct heat well, minimizing the temperature difference between the two sides of the thin tubesheets. This reduces thermal stress on the tubesheets during operation and enhances the cooling effect. Furthermore, the tie bars connect the thin tubesheets and thick tubesheets into a single unit, strengthening the thin tubesheets and making them less prone to deformation and maintaining a flat surface. This prevents the connection between the thin tubesheets and the shell from being subjected to alternating bending loads, allowing the thin tubesheets to withstand greater pressure.

[0006] From the above, we can see that, on the one hand, since the thin tube sheet and the thick tube sheet are welded and fixed by a large number and dense arrangement, welding and fixing are difficult, and the tie rods and the thick tube sheet are fillet welded, and the fixing strength is low; on the other hand, due to the existence of the thick tube sheet and the dense distribution of the tie rods, the axial channel of the shell-side space is blocked by the thick tube sheet. Although there is a gap between the tube holes of the thick tube sheet and the heat exchange tubes, the cooling water flow in the shell-side space is still greatly restricted, affecting the heat exchange effect. Summary of the Invention

[0007] In response to the above technical problems in the prior art, the present invention provides a flexible tube sheet structure and a corresponding waste heat boiler that can cope with the shell-tube pressure difference. The flexible tube sheet structure is easy to weld, increases the axial flow rate of cooling water in the shell, and improves the heat exchange effect.

[0008] To achieve the above objectives, the present invention provides the following technical solutions:

[0009] Provided is a flexible tube sheet structure for coping with shell-to-tube pressure differential, comprising a thin tube sheet and a plurality of support plates arranged in parallel, each support plate comprising a plate body and a plurality of tie rods, the plurality of tie rods being arranged on the side of the plate body close to the thin tube sheet, the thin tube sheet having a plurality of rows of support holes, the plurality of tie rods of the support plate being inserted into the corresponding rows of support holes and fixed by countersunk welding;

[0010] A plurality of reinforcing plates are welded and fixed between every two adjacent support plates; the improved flexible tube plate structure also includes a retaining ring for limiting the support plates.

[0011] Further preferably, a step is provided on the side of the plate body, and the inner side of the retaining ring is adapted to one side of the step to radially limit the support plate; the end face of the retaining ring is adapted to the other side of the step and there is an expansion gap between them, so that when the flexible deformation of the thin plate tube drives the support plate to displace, the retaining ring axially limits the stroke of the displaced support plate.

[0012] Further preferably, the step of the plate body is provided on the side close to the thin tube sheet, so that the retaining ring can limit the travel of the support plate toward the thin tube sheet, so as to be applicable to the occasion where the shell side pressure is greater than the tube side pressure;

[0013] Or the step of the plate body is set on the side away from the thin tube sheet, so that the retaining ring can limit the travel of the support plate in the direction away from the thin tube sheet, which is suitable for occasions where the tube side pressure is greater than the shell side pressure;

[0014] Or steps are provided on both sides of the plate body away from and close to the thin tube sheet, so that the retaining ring can limit the travel of the support plate in the direction away from and close to the thin tube sheet, so as to be suitable for occasions where either the tube side pressure or the shell side pressure is larger.

[0015] Further preferably, the reinforcing plate is a long strip-shaped plate, and the reinforcing plate is inserted and welded between two adjacent support plates.

[0016] Further preferably, the plate body and the pull rod of each support plate are an integrated structure.

[0017] Further preferably, the supporting hole is a circular hole, and the pull rod is a round rod that matches the supporting hole.

[0018] Further preferably, the plate body has multiple slots running through its thickness, and the multiple slots are arranged along the width and length of the plate body; and / or the reinforcing plate has multiple slots running through its thickness, and the multiple slots are arranged along the width and length of the reinforcing plate.

[0019] Further preferably, the baffle ring is provided with a plurality of liquid holes arranged around its axis.

[0020] The waste heat boiler with the above-mentioned flexible tube sheet structure includes an inlet tube box, an outlet tube box and a shell-side cylinder. The shell-side cylinder has multiple heat exchange tubes built in. The thin tube sheet is connected to the inlet tube box, and the retaining ring is welded and fixed to the inner wall of the shell-side cylinder. One end of the heat exchange tube passes through between two adjacent support plates and then connects to the inlet tube box through the thin tube sheet; the shell-side cylinder is also provided with a rear tube sheet, and the other end of the heat exchange tube passes through the rear tube sheet and connects to the outlet tube box.

[0021] Further preferably, the multiple reinforcing plates between each two adjacent support plates are arranged along the width direction of the support plates: the multiple heat exchange tubes are arranged in a rectangular manner in a longitudinal and transverse alignment, and the reinforcing plates and the support plates are arranged perpendicular to each other; or the multiple heat exchange tubes are arranged in a triangular manner in an adjacent staggered row, and the reinforcing plates are arranged obliquely relative to the support plates, and the inclination directions of the reinforcing plates in two adjacent rows are the same or opposite.

[0022] Beneficial effects of the present invention:

[0023] The flexible tube sheet structure for coping with shell-to-tube pressure difference and the corresponding waste heat boiler of the present invention have the following effects compared with the prior art:

[0024] 1) Due to the support plate reinforcement of the thin tube sheet, the thickness of the thin tube sheet can be made thinner than that of the traditional tube sheet. The connection structure between the heat exchange tube and the thin tube sheet is easier to achieve full penetration deep hole welding, ensuring the quality of the tube head and avoiding high temperature failure and crevice corrosion problems in the connection welds between the heat exchange tube and the thick tube sheet;

[0025] 2) The combination of support plates and retaining rings can enhance the strength of thin tube sheets, preventing them from bending and deforming significantly during use, which could cause equipment failure.

[0026] 3) The connection between the support plate and the reinforcement plate can avoid problems such as instability of each support plate along the arrangement direction;

[0027] 4) The thin tube sheets are welded together through the support plates. The retaining rings, which are not easily deformed, connect the thin tube sheets into one piece through the support plates with greater rigidity, thereby strengthening the strength of the thin tube sheets and preventing them from deformation.

[0028] 5) Compared with the existing technology of densely welding multiple tie bars separately, the present invention can arrange and weld each support plate, which facilitates the welding operation and reduces the manufacturing difficulty;

[0029] 6) Each row of tie rods is connected to each other by the plate body, which has higher overall strength and provides more effective reinforcement for the thin tube sheet;

[0030] 7) Since the thick tube sheet of the prior art is eliminated, the axial channel of the shell side space is not blocked by the thick tube sheet, thereby increasing the axial flow rate of cooling water in the shell side and improving the heat exchange effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of the structure of the waste heat boiler in the embodiment.

[0032] Figure 2 It is the specific structure diagram of position I in the figure.

[0033] Figure 3 for Figure 2 Cross-sectional view in the HH direction.

[0034] Figure 4 Schematic diagram of the support plate in the embodiment.

[0035] Figure 5 for Figure 4 Another visual diagram.

[0036] Figure 6 Schematic diagram of a row of reinforcement plates in an embodiment.

[0037] Figure 7 Schematic diagram of the rectangular arrangement of multiple heat exchange tubes in the embodiment, with a viewing angle of Figure 2 A direction.

[0038] Figure 8 For Figure 7 Schematic diagram of the arrangement of the support plate and reinforcement plate on the foundation, viewing angle Figure 2 B direction.

[0039] Figure 9 Schematic diagram of the triangle arrangement of multiple heat exchange tubes in the embodiment, with a viewing angle of Figure 2 A direction.

[0040] Figure 10 For Figure 9 Schematic diagram of the arrangement of the support plate and reinforcement plate on the foundation, viewing angle Figure 2 B direction.

[0041] Figure 11 For Figure 9 Schematic diagram of another arrangement of support plates and reinforcement plates on the foundation, with a viewing angle of Figure 2 B direction.

[0042] Figure 12 This is a schematic diagram of Example 2, in which the reinforcement plate is shown in a simplified manner.

[0043] Figure 13 This is a schematic diagram of Example 3, in which the reinforcement plate is shown in a simplified manner.

[0044] Reference numerals:

[0045] Inlet pipe box 1, improved flexible tube sheet structure 2, shell-side cylinder 3, rear tube sheet 4, outlet pipe box 5, thin tube sheet 6, support plate 7, reinforcement plate 8, retaining ring 9, heat exchange tube 10, support hole 11, tie rod 12, plate body 13, slot 14, liquid hole 15, expansion gap 16, step 17. DETAILED DESCRIPTION

[0046] The present invention is described in detail below with reference to specific embodiments and accompanying drawings.

[0047] Example 1

[0048] One embodiment of the waste heat boiler of the present invention is as follows Figures 1 to 11 As shown, it includes an inlet pipe box 1, an outlet pipe box 5 and a shell-side cylinder 3. The end of the shell-side cylinder 3 near the inlet pipe box 1 is provided with an improved flexible tube sheet structure 2. The improved flexible tube sheet structure 2 includes a thin tube sheet 6 and a plurality of support plates 7 arranged radially in parallel along the shell-side cylinder 3. Each support plate 7 includes a plate body 13 and a plurality of tie rods 12 of a mutually integrated structure. The plurality of tie rods 12 are arranged on the side of the plate body 13 near the thin tube sheet 6; the thin tube sheet 6 has a plurality of rows of support holes 11, and the plurality of tie rods 12 of the support plate 7 are inserted into the corresponding rows of support holes 11 and are welded and fixed by countersunk welding and polished after welding. The support holes 11 are circular holes, and the tie rods 12 are round rods that match the support holes 11. The "thinness" of the thin tube sheet 6 is relative; its thickness must meet the requirements for flexible deformation. Because the support plate 7 is provided to strengthen the thin tube sheet 6, the thickness of the thin tube sheet 6 can be made thinner than traditional tube sheets. The thin tube sheet 6 is welded together via the tie rods 12 of the support plate 7. The non-deformable retaining ring 9 connects the thin tube sheet 6 into a whole through the more rigid support plate 7, thereby strengthening the thin tube sheet 6, preventing deformation of the thin tube sheet 6, and avoiding problems such as instability of the support plates 7 along the arrangement direction. Furthermore, compared to the existing technology of densely welding multiple tie rods separately, this embodiment can arrange and weld each support plate 7, making the welding operation convenient and reducing the manufacturing difficulty.

[0049] In order to strengthen the strength of the multiple support plates 7 in the arrangement direction, multiple reinforcing plates 8 are welded and fixed between each two adjacent support plates 7. The multiple reinforcing plates 8 are arranged along the width direction of the support plates 7, so that the multiple support plates 7 and the multiple reinforcing plates 8 form a whole. The reinforcing plates 8 are long strips 13, and the reinforcing plates 8 are inserted and welded between each two adjacent support plates 7. In practice, according to the different layout methods of the multiple heat exchange tubes 10, the multiple reinforcing plates 8 can be arranged in various ways: for example, Figure 7 The plurality of heat exchange tubes 10 shown are arranged in a rectangular manner in a longitudinal and transverse alignment, and the reinforcing plate 8 and the supporting plate 7 are as shown in FIG. Figure 8 As shown in the mutually perpendicular tic-tac-toe arrangement; and for Figure 9 The plurality of heat exchange tubes 10 are arranged in a triangular pattern with adjacent rows staggered. The reinforcing plates 8 are arranged obliquely relative to the support plates 7. The inclination direction of the reinforcing plates 8 in two adjacent rows can be as follows: Figure 10 As shown, or Figure 11 The shown ones are tilted in opposite directions.

[0050] Two retaining rings 9 are welded to the inner wall of the shell-side cylinder 3. L-shaped steps 17 are provided on the left and right sides of the support plate 7 near the shell-side cylinder 3. The inner side of the retaining ring 9 fits the radial side of the step 17 to radially limit the support plate 7. The end face of the retaining ring 9 fits the axial side of the step 17, and an expansion gap exists between them. When the flexible deformation of the thin plate tube drives the support plate 7 to move, the retaining ring 9 axially limits the travel of the displaced support plate 7. When the temperature is high, the support plate 7 will expand and elongate. When this expansion is out of sync with the shell-side cylinder 3, an expansion gap 16 needs to be reserved between the retaining ring 9 and the support plate 7. For example, when the tube-side pressure is high, the support plate 7 tends to move to the right, so an expansion gap 16 can be reserved between the support plate 7 and the left retaining ring 9. Conversely, when the shell-side pressure is high, the support plate 7 tends to move to the left, so some expansion gap 16 can be reserved between the support plate 7 and the right retaining ring 9. The combination of the support plate 7 and the retaining ring 9 can strengthen the strength of the thin tube sheet 6 and prevent the thin tube sheet 6 from being greatly bent and deformed during use, which may cause equipment failure. Since the support plate 7 and the retaining ring 9 can strengthen the thin tube sheet 6, the thick tube sheet of the prior art can be eliminated, and the axial channel of the shell space is not blocked by the thick tube sheet, thereby increasing the axial flow rate of the cooling water in the shell and improving the heat exchange effect. The reinforcing plate 8 closest to the inner wall of the shell cylinder 3 is also provided with a step 17. The matching relationship between the step 17 and the retaining ring 9 is the same as the matching relationship between the step 17 of the support plate 7 and the retaining ring 9. In this way, the retaining ring 9 limits the overall position of the support plate 7 and the reinforcing plate 8 more evenly, stably and reliably.

[0051] The shell-side cylinder 3 houses multiple heat exchange tubes 10 arranged in parallel. A thin tube sheet 6 connects to the inlet manifold 1. One end of the heat exchange tube 10 passes between two adjacent support plates 7 and then connects to the inlet manifold 1 via the thin tube sheet 6. The welded connection between the heat exchange tubes 10 and the thin tube sheet 6 facilitates full-penetration deep-hole welding, ensuring tube head quality, compared to the traditional connection between the heat exchange tubes 10 and thicker tube sheets. This full-penetration deep-hole welding of the thin tube sheet 6 avoids high-temperature failure and crevice corrosion in the welds connecting the heat exchange tubes 10 and thicker tube sheets, compared to the traditional connection between thick tube sheets and heat exchange tubes 10. The shell-side cylinder 3 also features a rear tube sheet 4, through which the other end of the heat exchange tube 10 passes before connecting to the outlet manifold 5.

[0052] In this embodiment, the plate body 13 and the reinforcing plate 8 are both provided with a plurality of elliptical slots 14 that penetrate their own thickness, and the plurality of slots 14 are arranged along the width and length directions of the plate body 13 and the reinforcing plate 8. This structure enables the shell-side cooling water to flow quickly and evenly, preventing the occurrence of high-temperature dead corners that may cause high-temperature failure of the equipment.

[0053] Example 2

[0054] The second specific embodiment of the waste heat boiler of the present invention is combined with Figure 12 As shown, the main technical solutions of this embodiment are the same as those of embodiment 1. The technical features not described in this embodiment are explained using embodiment 1 and are not described in detail here. The difference between this embodiment and embodiment 1 is that the shell-side cylinder 3 is only provided with a retaining ring 9, and the step 17 of the plate body 13 is arranged on the side close to the thin tube plate 6, which limits the leftward movement of the support plate 7 in the axial direction, and is suitable for use in an environment with high shell-side pressure.

[0055] In this embodiment, the retaining ring 9 is provided with a plurality of liquid holes 15 arranged around its axis. This structure enables the shell-side cooling water to flow quickly and evenly, preventing the formation of high-temperature dead corners that could cause high-temperature failure of the equipment. The liquid holes 15 are also applicable to the retaining ring 9 of Example 1.

[0056] Example 3

[0057] The third embodiment of the waste heat boiler of the present invention is combined with Figure 13 As shown, the main technical solutions of this embodiment are the same as those of Example 2. The technical features not described in this embodiment are explained using Example 2 and are not described in detail here. The difference between this embodiment and Example 2 is that the step 17 of the plate body 13 is arranged on the side away from the thin tube plate 6, which limits the rightward movement of the support plate 7 in the axial direction and is suitable for use in an environment with high tube pressure.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A flexible tube sheet structure for coping with shell-to-tube pressure differential, characterized by: The invention comprises a thin tube sheet and a plurality of support plates arranged in parallel, each support plate comprising a plate body and a plurality of tie rods, the plurality of tie rods being arranged on the side of the plate body close to the thin tube sheet, the thin tube sheet being provided with a plurality of rows of support holes, the plurality of tie rods of the support plate being inserted into the corresponding rows of support holes and being fixed by countersunk welding; A plurality of reinforcing plates are welded and fixed between each two adjacent support plates; the flexible tube sheet structure also includes a retaining ring for limiting the support plates; A step is provided on the side of the plate body, and the inner side of the retaining ring movably adapts to one side of the step to radially limit the support plate; the end face of the retaining ring adapts to the other side of the step and an expansion gap is provided between them, so that when the flexible deformation of the thin plate tube drives the support plate to move, the retaining ring axially limits the travel of the displaced support plate; The baffle ring is provided with a plurality of liquid holes arranged around its axis.

2. The flexible tube sheet structure for coping with shell-to-tube pressure difference according to claim 1, characterized in that: The step of the plate body is set on the side close to the thin tube sheet, so that the retaining ring can limit the travel of the support plate towards the thin tube sheet, which is suitable for occasions where the shell side pressure is greater than the tube side pressure; Or the step of the plate body is set on the side away from the thin tube sheet, so that the retaining ring can limit the travel of the support plate in the direction away from the thin tube sheet, which is suitable for occasions where the tube side pressure is greater than the shell side pressure; Or steps are provided on both sides of the plate body away from and close to the thin tube sheet, so that the retaining ring can limit the travel of the support plate in the direction away from and close to the thin tube sheet, so as to be suitable for occasions where either the tube side pressure or the shell side pressure is larger.

3. The flexible tube sheet structure for coping with shell-to-tube pressure difference according to claim 1, characterized in that: The reinforcing plate is a long strip plate body, and the reinforcing plate is inserted and welded between two adjacent supporting plates.

4. The flexible tube sheet structure for coping with shell-to-tube pressure difference according to claim 1, characterized in that: The plate body and the pull rod of each supporting plate are an integrated structure.

5. The flexible tube sheet structure for coping with shell-to-tube pressure difference according to claim 1, characterized in that: The supporting hole is a circular hole, and the pull rod is a round rod body matched with the supporting hole.

6. The flexible tube sheet structure for coping with shell-to-tube pressure difference according to claim 1, characterized in that: The plate body has multiple slots extending through its thickness, and the multiple slots are arranged along the width and length of the plate body; and / or the reinforcing plate has multiple slots extending through its thickness, and the multiple slots are arranged along the width and length of the reinforcing plate.

7. A waste heat boiler having a flexible tube sheet structure for coping with a shell-and-tube pressure difference according to any one of claims 1 to 6, characterized in that: It includes an inlet pipe box, an outlet pipe box and a shell-side cylinder. The shell-side cylinder has multiple heat exchange tubes built in. The thin tube sheet is connected to the inlet pipe box, and the retaining ring is welded and fixed to the inner wall of the shell-side cylinder. One end of the heat exchange tube passes through between two adjacent support plates and then connects to the inlet pipe box through the thin tube sheet. The shell-side cylinder is also provided with a rear tube sheet, and the other end of the heat exchange tube passes through the rear tube sheet and is connected to the outlet pipe box.

8. The waste heat boiler according to claim 7, characterized in that: Multiple reinforcing plates between every two adjacent support plates are arranged along the width direction of the support plates: multiple heat exchange tubes are arranged in a rectangular manner in a longitudinal and transverse alignment, and the reinforcing plates and the support plates are arranged perpendicular to each other; or multiple heat exchange tubes are arranged in a triangular manner in an adjacent staggered manner, and the reinforcing plates are arranged obliquely relative to the support plates, and the inclination directions of the reinforcing plates in two adjacent rows are the same or opposite.

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