Multi-connected heat exchanger

Abstract

The invention is a divisional application of a Chinese patent application with the application date of July 26, 2023, the application number of 202310921585. X and the name of'an integrally forcibly sealed multi-connected heat exchanger ', and relates to the technical field of shell-and-tube heat exchangers in petrochemical equipment, in particular to a multi-connected heat exchanger which comprises a plurality of sections of heat exchange modules which are sequentially connected in series, each section of heat exchange module comprises a tube shell and a tube bundle, the tube bundle comprises a plurality of heat exchange tubes and two tube plates, the two tube plates are fixed to the two ends of the tube shell to jointly define a shell pass, the heat exchange tubes are arranged in the shell pass side by side, and a connecting tube communicated with the shell pass is arranged on the side wall of the tube shell; a middle tube box is arranged between every two adjacent heat exchange modules, end tube boxes are arranged at the two ends of the whole heat exchange modules, and the end tube boxes, heat exchange tubes of all the heat exchange modules and the middle tube boxes are communicated to form multiple sections of tube passes. The connecting pipe also serves as a forced sealing structure and enables the multiple sections of tube passes to be sequentially connected in a sealed mode, the overall weight of the heat exchanger and a supporting structure of the heat exchanger are reduced, and the equipment space and the construction cost are saved.

Description

[0001] This application is a divisional application of the Chinese patent application with application date of July 26, 2023, application number 202310921585.X, and name “A multi-connected heat exchanger with integral forced sealing”. Technical Field

[0002] The present invention relates to the technical field of shell and tube heat exchangers in petrochemical equipment, in particular to heat exchangers used in petrochemical industry, coal chemical industry, fertilizer industry, air conditioning and refrigeration, and power facilities, and specifically to a multi-connected heat exchanger. Background Art

[0003] In the existing technology, the shell and tube heat exchanger is the most widely used type of heat exchanger. The shell and tube heat exchanger is also called a shell and tube heat exchanger or a shell and tube condenser. It is widely used in the fields of chemical industry, petroleum, medicine, food, light industry, metallurgy, coking, etc. for convection heat transfer of "liquid-liquid", "steam-steam", and "steam-liquid" heat exchange, as well as heat exchange and condensation processes such as steam condensation and liquid evaporation heat transfer.

[0004] The shell and tube heat exchanger in the prior art generally has the following structure: Figure 1 As shown, it is mainly composed of main components such as tube bundle 01, shell 02, and tube box 03. Among them, tube bundle 01 is the core component of the shell and tube heat exchanger. Tube bundle 01 is usually composed of heat exchange tubes 011, support plates (or baffles) 012, distance tube tie rod assemblies 013 and tube sheets 014. The rows of heat exchange tubes are supported by support plates (or baffles), and their two ends pass through the tube holes of the tube sheets and are connected to the tube sheets to ensure the sealing and strength of the joints.

[0005] Depend on Figure 1 As can be seen, traditional heat exchangers are equipped with pipe boxes to facilitate disassembly and inspection of vulnerable structures such as the tube bundle and pipe joints. The tube bundle and pipe box must be sealed with flange bolts, and the seals must be enforced on both ends of the pipe box. With the development of society and the ever-increasing scale of petrochemical plant construction, the drawbacks of this traditional heat exchanger structure are becoming increasingly prominent.

[0006] First, the increasing number of applications in oil refining and petrochemical plants where heat exchangers are connected in series takes up unnecessary space. Each connection requires a set of flange bolts, increasing construction costs. While eliminating the connecting pipes saves space, flange bolts still need to be used to seal the series heat exchangers, creating a complex structure. To meet the "dual carbon" development goals, it's necessary to improve the combined structure of these heat exchangers.

[0007] Second, as temperatures in petrochemical processes continue to rise, the structural dimensions of newly built heat exchangers not only exceed the nominal diameter limit of 4000mm set forth in the GB / T 151-2014 "Heat Exchangers" standard, but are also being integrated with reactors to form ethylene oxide and propylene oxide reactors, resulting in ever-increasing processing capacity. On the one hand, sealing large-diameter pressure vessels requires the processing of connecting flanges from large forgings. Efficiently transporting large flanges over long distances poses traffic safety concerns, and the integrated manufacturing and application of sealing gaskets with diameters exceeding 4000mm present further challenges. Furthermore, large-diameter flanges require numerous fastening bolts, necessitating significant assembly and disassembly work, and the difficulty in uniformly tightening each bolt, leading to undesirable consequences. Furthermore, the intense and complex reaction processes, coupled with uneven temperatures and thermal stresses, complicate pressure vessel sealing. Internal leakage of the media can impact the production and quality of chemical products and even cause environmental pollution.

[0008] Solving the aforementioned technical bottlenecks in development requires advancing overall structural thinking and strengthening the structure from the perspective of reducing costs and making better use of existing resources. Therefore, it is of engineering significance to improve the above-mentioned problems in the existing technology. Summary of the Invention

[0009] In view of the above technical problems in the prior art, the present invention provides a multi-connected heat exchanger.

[0010] To achieve the above objectives, the present invention provides the following technical solutions:

[0011] A multi-connected heat exchanger is provided, comprising a plurality of heat exchange modules connected in series, each heat exchange module comprising a tube shell and a tube bundle located within the tube shell, the tube bundle comprising a plurality of heat exchange tubes and two tube sheets, the two tube sheets being fixed at both ends of the tube shell to form a shell side, a plurality of heat exchange tubes being arranged in parallel within the shell side and having their ends fixed to corresponding tube sheets, a pipe connecting the shell side being provided on the side wall of the tube shell; an intermediate pipe box being provided between adjacent heat exchange modules, an end pipe box being provided at both ends of the heat exchange module as a whole, the end pipe box, the heat exchange tubes of each heat exchange module and the intermediate pipe box being connected to form a multi-section tube side; a forced sealing structure being provided on the outside of the heat exchange module, which simultaneously seals and connects the multi-section tube sides in sequence. The pipe also serves as the forced sealing structure, the pipe being a curved pipe, the end of which is provided with a connecting flange, a short stud and a nut locking member, and the pipes connecting different heat exchange modules being connected and fixed to each other via the short stud and the nut locking member.

[0012] As a further alternative, the pipes of non-adjacent, mutually separated heat exchange modules are connected to each other.

[0013] As a further optional solution, the shell and tube diameters of adjacent heat exchange modules are the same, and the intermediate pipe box between the adjacent heat exchange modules is a straight cylinder; or the shell and tube diameters of adjacent heat exchange modules are different, and the intermediate pipe box between the adjacent heat exchange modules is a frustum cylinder.

[0014] As a further optional solution, the heat exchange module also includes baffles, distance tubes and pull rods located in the shell side. Multiple baffles are arranged in parallel and have tube holes for the heat exchange tubes to pass through. The ends of the pull rods are fixed to the tube sheets and pass through multiple baffles. The distance tubes are sleeved outside the pull rods and axially press against the baffles, thereby limiting the distance between different baffles.

[0015] Beneficial effects of the present invention:

[0016] The multi-connected heat exchanger of the present invention has the following advantages compared with the prior art:

[0017] (1) It avoids the need for an independent set of flange bolt fasteners at each connection in the prior art, reduces the large flanges for connecting and sealing the intermediate sections, reduces the overall weight of the heat exchanger and its supporting structure, and saves equipment space and construction costs.

[0018] (2) During the operation of the heat exchanger, the temperature of the tube bundle and the shell is higher than the temperature of the fasteners around the shell. The thermal elongation of the shell is slightly longer than that of similar steel fasteners, which makes the connection ports of each section stick together more tightly to strengthen the seal and improve the overall strength and overall stiffness of the heat exchanger.

[0019] (3) The integral forced seal can be installed on site, and the segmented structure of the heat exchangers connected in series can be transported in sections, which facilitates safe and efficient transportation and reduces transportation costs.

[0020] (4) The integral forced seal can be installed on site, and the segmented structure can be hoisted in sections, which facilitates on-site construction organization and reduces hoisting costs.

[0021] (5) It saves equipment space and construction costs. The heat exchanger has the characteristics of simple structure, easy assembly and disassembly, and long service life.

[0022] (6) The integral forced-sealed multi-section heat exchanger is particularly suitable for high-temperature, low-pressure, large-diameter, extra-long, and extra-heavy multi-section heat exchange conditions of the tube side fluid. It is suitable for both vertical and horizontal multi-section heat exchangers and has the characteristics of simple structure, easy assembly and disassembly, and long service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural diagram of a heat exchanger in the prior art.

[0024] Figure 2 This is a structural diagram of Example 1 of a multi-connected heat exchanger in the embodiments.

[0025] Figure 3 This is a structural diagram of Example 2 of a multi-connected heat exchanger in the embodiments.

[0026] Figure 4 This is a structural diagram of Example 3 of a multi-connected heat exchanger in the embodiments.

[0027] Figure 5 This is a structural diagram of Example 4 of a multi-connected heat exchanger in the embodiments.

[0028] Figure 6 This is a structural diagram of Example 5 of a multi-connected heat exchanger in the embodiments.

[0029] Figure 7 This is a structural diagram of Example 6 of a multi-connected heat exchanger in the embodiments. DETAILED DESCRIPTION

[0030] The present invention is described in detail below with reference to specific embodiments and accompanying drawings.

[0031] One of the specific embodiments of the multi-connected heat exchanger of the present invention is as follows: Figure 2 As shown, it includes multiple heat exchange modules connected in series. In practice, the number of heat exchange modules can be changed to other values as needed. Figure 2 The figure shows four heat exchange modules, which are the first heat exchange module 1, the second heat exchange module 2, the third heat exchange module 3 and the fourth heat exchange module 4 from bottom to top. The structures of the heat exchange modules in each section are basically the same. Figure 2Only the third heat exchange module 3 is specifically illustrated with its internal structure, while the other heat exchange modules are briefly illustrated. The third heat exchange module 3 includes a tube shell 14 and a tube bundle located within the tube shell 14. The tube bundle includes a plurality of heat exchange tubes 11 and two tube sheets 12. The two tube sheets 12 are fixed to the two ends of the tube shell 14 and together form a shell side. The plurality of heat exchange tubes 11 are arranged in parallel within the shell side and their two ends are fixed to the corresponding tube sheets 12. The side wall of the tube shell 14 is provided with a connecting pipe 141 for circulating the cooling medium that is connected to the shell side. The heat exchange module also includes a baffle 10, a distance tube, and a tie rod located within the shell side. The plurality of baffles 10 are arranged in parallel and have tube holes for the heat exchange tubes to pass through. The ends of the tie rods are fixed to the tube sheets 12 and pass through the plurality of baffles 10. The distance tubes are sleeved outside the tie rods and axially press against the baffles 10, thereby limiting the distance between different baffles 10. Intermediate pipe boxes are located between adjacent heat exchange modules, and end pipe boxes are located at both ends of the entire heat exchange module. For example, a tapered lower end pipe box 5 is located at the lower end of the first heat exchange module 4. A first intermediate pipe box 6 is located between the first and second heat exchange modules 2. A second intermediate pipe box 7 is located between the second and third heat exchange modules 3. A third intermediate pipe box 8 is located between the third and fourth heat exchange modules 4. A top pipe box 9 is located on top of the fourth heat exchange module 4. It can be seen that the shell and tube diameters of adjacent heat exchange modules can be the same or different. If the shell and tube diameters are the same, the intermediate pipe boxes between adjacent heat exchange modules are straight cylinders; if the shell and tube diameters are different, the intermediate pipe boxes between adjacent heat exchange modules are frustoconical cylinders. The lower end pipe box 5, the heat exchange tubes of the first heat exchange module 1, the first intermediate pipe box 6, the heat exchange tubes of the second heat exchange module 2, the second intermediate pipe box 7, the heat exchange tubes of the third heat exchange module 3, the third intermediate pipe box 8, the heat exchange tubes of the fourth heat exchange module 4, and the upper end pipe box 9 are connected in sequence, thus forming a multi-section pipe pass. The plurality of heat exchange modules are integrally supported on the skirt 13 as a vertical multi-connected heat exchanger, which can actually be changed to a horizontal multi-connected heat exchanger arranged laterally.

[0032] In this embodiment, a forced sealing structure is provided on the outside of the heat exchange module, which simultaneously seals and connects the multiple tube sections in sequence. Specifically, the forced sealing structure includes a first extension flange 15, a second extension flange 16, studs, and fastening nuts 17. The first extension flange 15 and the second extension flange 16 are respectively fixed to the tube sheets of different heat exchange modules. Figure 2 The forced seal structure simultaneously seals all tubes. The first extension flange is fixed to the upper tube sheet of the first heat exchange module 1, and the second extension flange 16 is fixed to the lower tube sheet of the fourth heat exchange module 4, which is the last. The first extension flange 16 and the second extension flange 17 are fixed to each other via studs and fastening nuts 17, thereby tightening the first extension flange 15 and the second extension flange 16 toward each other. Multiple sets of studs and fastening nuts 17 are arranged around the circumference of the heat exchanger.

[0033] As can be seen above, the pipe connections between adjacent heat exchanger sections do not rely on separate flange bolts for forced sealing. Instead, all pipe connections between the heat exchanger sections are centrally secured and sealed via a forced sealing structure installed around the perimeter of the heat exchanger. This eliminates the need for large flanges for individual connection and sealing between intermediate sections, reducing the overall weight of the heat exchanger and its supporting structure, saving equipment space and construction costs. The heat exchanger boasts a simple overall structure, easy assembly and disassembly, and a long service life. A single set of standard studs and fastening nuts 17 effectively achieves forced connection between the tube and shell sides of all heat exchanger sections, achieving high efficiency.

[0034] The above studs are studs without a shoulder in the middle, or studs with a shoulder in the middle. The shoulder is used to support the corresponding extension flange. Loosening the nut at one end of the stud does not affect the tightening of the nut at the other end of the stud.

[0035] Example 2

[0036] The second specific embodiment of the multi-connected heat exchanger of the present invention has the same main technical solution as that of the first embodiment. The features not explained in the present embodiment are explained in the first embodiment and will not be described in detail here. The difference between the present embodiment and the first embodiment is that Figure 3 As shown, the forced sealing structure only seals and connects part of the pipe passage at the same time: the first extension flange 15 is fixed to the upper tube sheet of the first heat exchange module 1 in the first position, and the third extension flange 18 is fixed to the lower tube sheet of the third heat exchange module 3 in the middle. The shorter studs and fastening nuts 19 realize the forced connection of the pipe passages of the first heat exchange module 1, the second heat exchange module 2, and the third heat exchange module 3. As for the pipe passage of the fourth heat exchange module 4, a traditional connection method can be adopted, that is, a compatible mode combining the traditional and this innovation. This embodiment mainly illustrates that only the pipe passages of part of the heat exchange module adopt the overall forced sealing structure. Similarly, the first extension flange can be fixed to the lower tube sheet of the fourth heat exchange module 4 in the last position, and the second extension flange can be fixed to the tube sheet of the second heat exchange module / third heat exchange module. They can then be tightened together by studs and fastening nuts to achieve the overall forced sealing of part of the pipe passage.

[0037] Example 3

[0038] The third embodiment of the present invention is a multi-connected heat exchanger. The main technical solution of this embodiment is the same as that of the first embodiment. The features not explained in this embodiment are explained in the first embodiment and will not be described again. The difference between this embodiment and the first embodiment is that Figure 4As shown, all connections between the pipes of each heat exchange module are centrally secured and sealed by a forced seal structure installed around the perimeter of the heat exchanger. This forced seal structure also includes a third extension flange 18 fixed to the tube sheet of the intermediate heat exchange module. The studs are divided into upper studs 20 and lower studs 21. The ends of the lower studs 21 pass through the first extension flange 15 and the third extension flange 18, respectively, and are screwed into the fastening nuts for locking. The ends of the upper studs 20 pass through the second extension flange 16 and the third extension flange 18, respectively, and are screwed into the fastening nuts for locking.

[0039] This embodiment uses two sets of studs of different specifications, upper studs 20 and lower studs 21. The two sets of studs are installed alternately along the circumferential intervals of the flange. While achieving forced connection between the tube side and the shell side of all sections of the heat exchange modules, after the seals between the upper sections of the heat exchange modules are disassembled, the seals between the lower sections of the heat exchange modules can continue to be maintained, or vice versa, while the seals between the lower sections of the heat exchange modules are disassembled, the seals between the upper sections of the heat exchange modules can be maintained.

[0040] Of course, using only the upper stud 20 or the lower stud 21 of the same set of double-headed studs can also realize the forced connection of the tube side and the shell side of the multi-stage heat exchange module, which is equivalent to changing to the structure of Example 2.

[0041] Example 4

[0042] The fourth embodiment of the multi-connected heat exchanger of the present invention has the same main technical solution as that of the first embodiment. The features not explained in the present embodiment are explained in the first embodiment and will not be described again here. The difference between the present embodiment and the first embodiment is that Figure 5 As shown, the forced sealing structure also includes a platform steel structure 22, which is fixed to an external reinforced slow-setting soil foundation 25. The ends of some studs 24 pass through the first extension flange 15 and the platform steel structure 22, respectively, and are then screwed into fastening nuts. The ends of other studs 23 pass through the third extension flange 18 and the platform steel structure 22, respectively, and are then screwed into fastening nuts. In this way, the pipes of the first heat exchange module 1, the second heat exchange module 2, and the third heat exchange module 3 are completely sealed.

[0043] In practice, the third extension flange 18 can be relocated to the tube sheet of the fourth heat exchange module 4 as in Example 1. This way, the tubes of all four heat exchange modules are sealed by the mandatory sealing structure. Furthermore, in conjunction with the structure of Example 3, an extension flange can be installed on the lower tube sheet of the fourth heat exchange module 4. This extension flange can be secured to the third extension flange 18, the platform steel structure 22, or the first extension flange 15 via studs to achieve overall sealing. This embodiment illustrates the possibility of adding the platform steel structure 22 to provide more secure support for the extension flange, thereby improving overall strength and stability.

[0044] Example 5

[0045] The fifth specific embodiment of a multi-connected heat exchanger of the present invention has the same main technical solution as that of the first embodiment. The features not explained in the present embodiment are explained in the first embodiment and will not be described in detail here. The difference between the present embodiment and the first embodiment is that Figure 6 As shown, the pipe connecting the side wall of the shell and tube to the shell also serves as the forced sealing structure. The pipe is a bend pipe 26, and the end of the bend pipe 26 is provided with a connecting flange 27, a short stud and a nut locking piece 28. The pipes connected to different heat exchange modules are connected and fixed to each other via the short stud and the nut locking piece 28.

[0046] Considering the overall structure of these connections, the tension of the shell-side pipe of the upper heat exchange module assists the sealing of the tube and shell sides of the lower heat exchange module. Disassembly and inspection of the upper forced connection does not affect the lower forced connection. Long studs and their nut fasteners can also be eliminated.

[0047] Of course, the forced sealing of the pipes in this embodiment can coexist with the double-ended tie rods and platform steel structure of other embodiments, achieving forced sealing in multiple ways. The sealing of the pipes between the two heat exchange modules is achieved through a self-tightening seal caused by thermal expansion during operation. The platform steel structure and the rigid pipe structure jointly limit the thermal expansion of the heat exchanger, converting displacement loads into sealing loads to compress the gaskets.

[0048] Example 6

[0049] The sixth specific embodiment of a multi-connected heat exchanger of the present invention has the same main technical solution as that of the fifth embodiment. The features not explained in the present embodiment are explained in the fifth embodiment and will not be described in detail here. The difference between the present embodiment and the fifth embodiment is that Figure 6 As shown, the pipes of non-adjacent, mutually separated heat exchange modules are interconnected, such as the pipe 30 between the first heat exchange module 1 and the third heat exchange module 3, and the pipe 31 between the second heat exchange module 2 and the fourth heat exchange module 4. This connection method simultaneously realizes the forced connection of the first heat exchange module 1, the second heat exchange module 2, and the third heat exchange module 3 from an overall perspective, and also realizes the forced connection of the second heat exchange module 2, the third heat exchange module 3, and the fourth heat exchange module 4. There is an overlap between the two forced connections, and disassembling one of the forced connections does not affect the other forced connection. At the same time, it also realizes the forced connection of the shell side between the first heat exchange module 1 and the third heat exchange module 3, and the forced connection of the shell side between the second heat exchange module 2 and the fourth heat exchange module 4, and also eliminates the need for stud bolts and their nut fasteners.

[0050] In the description of the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connected," and "fixed" should be understood in a broad sense. For example, they may refer to fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention in specific circumstances.

[0051] The standard parts used in the present invention can all be purchased from the market, and special-shaped parts can be customized according to the description in the specification and the drawings. The specific connection methods of each part adopt conventional means such as mature bolts, rivets, welding, etc. in the existing technology. The machinery, parts and equipment all adopt conventional models in the existing technology, and the circuit connection adopts the conventional connection method in the existing technology, which will not be described in detail here.

[0052] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

[0053] 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 multi-connected heat exchanger, characterized by: It comprises a plurality of heat exchange modules connected in series in sequence, each heat exchange module comprises a tube shell and a tube bundle located in the tube shell, the tube bundle comprises a plurality of heat exchange tubes and two tube sheets, the two tube sheets are fixed to the two ends of the tube shell and together form a shell side, a plurality of heat exchange tubes are arranged in parallel in the shell side and their two ends are fixed to the corresponding tube sheets, and a connecting pipe connecting the shell side is provided on the side wall of the tube shell; an intermediate pipe box is provided between adjacent heat exchange modules, and end pipe boxes are provided at both ends of the heat exchange module as a whole, the end pipe boxes, the heat exchange tubes of each heat exchange module and the intermediate pipe box are connected to form a multi-section tube side; a forced sealing structure is provided on the outside of the heat exchange module, which simultaneously seals and connects the multiple sections of tube sides in sequence; the connecting pipe also serves as the forced sealing structure, the connecting pipe is a bent pipe, and the end of the bent pipe is provided with a connecting flange, a short stud and a nut locking piece, and the connecting pipes connected to different heat exchange modules are connected and fixed to each other via short studs and nut locking pieces.

2. The multi-connected heat exchanger according to claim 1, characterized in that: The pipes of non-adjacent, mutually separated heat exchange modules are connected to each other.

3. The multi-connected heat exchanger according to claim 1, characterized in that: The shell and tube diameters of adjacent heat exchange modules are the same, and the intermediate tube box between the adjacent heat exchange modules is a straight cylinder; or the shell and tube diameters of adjacent heat exchange modules are different, and the intermediate tube box between the adjacent heat exchange modules is a truncated cone cylinder.

4. The multi-connected heat exchanger according to claim 1, characterized in that: The heat exchange module also includes baffles, distance tubes and tie rods located in the shell side. Multiple baffles are arranged in parallel and have tube holes for the heat exchange tubes to pass through. The ends of the tie rods are fixed to the tube sheets and pass through multiple baffles. The distance tubes are sleeved outside the tie rods and axially press against the baffles, thereby limiting the distance between different baffles.

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