An integrally forced-sealed multi-connected heat exchanger

Abstract

The present invention relates to the technical field of shell-and-tube heat exchangers in petrochemical equipment, and particularly relates to a multi-connected heat exchanger with integral forced sealing, which includes multiple heat exchange modules connected in series in sequence. Each heat exchange module includes a shell and a tube bundle. The tube bundle includes multiple heat exchange tubes and two tube sheets. The two tube sheets are fixed at both ends of the shell to jointly enclose a shell side. The multiple heat exchange tubes are arranged side by side in the shell side. A nozzle communicating with the shell side is provided on the side wall of the shell. An intermediate header tank is provided between the heat exchange modules, and end header tanks are provided at both ends of the whole heat exchange module. The end header tanks, the heat exchange tubes of each heat exchange module and the intermediate header tank are connected and communicated to form multiple sections of tube passes. A forced sealing structure is arranged on the outer side of the heat exchange module, which simultaneously seals and connects the multiple sections of tube passes in sequence, avoiding the need for forced sealing with flange bolts between each intermediate section, reducing the overall weight of the heat exchanger and its supporting structure, saving equipment space and construction costs, and having the characteristics of simple structure, convenient installation and disassembly, and long service life as a whole.

Description

Technical Field

[0001] The present invention relates to the technical field of shell-and-tube heat exchangers in petrochemical equipment, and particularly to a heat exchanger dedicated for heat exchange in petrochemical, coal chemical, fertilizer industry, air-conditioning refrigeration, and power facilities. Specifically, it relates to a multi-connected heat exchanger with integral forced sealing. Background Art

[0002] In the prior art, the shell-and-tube heat exchanger is one of the most widely used heat exchangers. The shell-and-tube heat exchanger is also called a tubular heat exchanger or a tubular condenser, and is widely used in convective heat transfer of "liquid-liquid", "vapor-vapor", "vapor-liquid" heat exchange, as well as heat transfer condensation processes such as steam condensation and liquid evaporation in fields such as chemical industry, petroleum, medicine, food, light industry, metallurgy, and coking.

[0003] The general structure of the shell-and-tube heat exchanger in the prior art is as Figure 1 shown, and it is mainly composed of main components such as a tube bundle 01, a shell 02, and a tube box 03. Among them, the tube bundle 01 is the core component of the shell-and-tube heat exchanger. The tube bundle 01 is usually composed of heat exchange tubes 011, support plates (or baffle plates) 012, a fixed-distance tube tie rod assembly 013, and tube sheets 014. The rows of heat exchange tubes are supported by support plates (or baffle plates), and their two ends penetrate into the tube holes of the tube sheets and are connected to the tube sheets, so as to ensure the sealing performance and strength of the joints.

[0004] As Figure 1 can be seen, the traditional heat exchanger main body is provided with a tube box for inspecting vulnerable structures such as tube joints of the tube bundle after disassembly. The tube bundle and the tube box must be forced-sealed by flange bolts, and the two tube boxes at both ends are forced-sealed separately. With the development of social economy, the construction scale of petrochemical plants is getting larger and larger, and the disadvantages of this traditional structure of the heat exchanger are becoming more and more prominent.

[0005] First, in refinery and petrochemical plants, the scenario of combining multiple heat exchangers in series is becoming more and more common. The pipeline connection between single heat exchangers occupies unnecessary space, and each connection requires a set of flange bolt fasteners, increasing the engineering construction cost. If the connecting pipelines are cancelled, although a certain amount of space is saved, the flange bolt fasteners are still required for sealing between the series-connected heat exchangers before and after, and the structure is still relatively complex. Under the "dual carbon" development goal, it is necessary to improve the combined structure of such heat exchangers.

[0006] Second, as the temperature of the deep processing of petrochemical processes gets higher and higher, the structural dimensions of newly built heat exchangers not only break through the limit of the nominal diameter not exceeding 4,000 mm in the standard of GB / T 151—2014 "Heat Exchangers", but also are integrated with reactors to form ethylene oxide reactors, propylene oxide reactors, etc., and the processing capacity is also increasing. On the one hand, the sealing of large-diameter pressure shells requires the processing of connecting flanges with large forgings. There are traffic safety problems in the long-distance and efficient transportation of large flanges. There are more difficulties in the overall manufacturing and application process of large-diameter gaskets above 4,000 mm. On the other hand, the number of fastening bolts for large-diameter flanges is large, the installation and disassembly workload is large, and it is difficult to balance the tightening force of each bolt, resulting in adverse results caused by humans. On the other hand, the reaction process is intense and complex. The additional temperature difference stress caused by uneven temperature increases the sealing difficulty of the pressure shell. The internal leakage of the medium will affect the production and quality of chemical products, and even leak out and pollute the environment.

[0007] To solve the above technical bottleneck problems in development, it is necessary to promote the overall structural thinking and strengthen the structure particularly from the perspective of making more full use of existing resources while reducing cost investment. Therefore, it has engineering significance to improve the problems existing in the above-mentioned existing technologies. Summary of the Invention

[0008] In view of the above technical problems existing in the prior art, the present invention provides a multi-connected heat exchanger with integral forced sealing.

[0009] To achieve the above object, the present invention provides the following technical solutions:

[0010] Provide a multi-connected heat exchanger with integral forced sealing, including multiple heat exchange modules connected in series in sequence. Each heat exchange module includes a shell and a tube bundle located inside the shell. The tube bundle includes multiple heat exchange tubes and two tube sheets. The two tube sheets are fixed at both ends of the shell to jointly enclose a shell side. The multiple heat exchange tubes are arranged side by side in the shell side and their two ends are fixed to the corresponding tube sheets. A nozzle communicating with the shell side is provided on the side wall of the shell; an intermediate header is provided between adjacent heat exchange modules, and end headers are provided at both ends of the whole heat exchange module. The end headers, the heat exchange tubes of each heat exchange module and the intermediate header are connected and communicated to form multiple sections of tube sides; a forced sealing structure is arranged outside the heat exchange module, which simultaneously seals and connects the multiple sections of tube sides in sequence.

[0011] As a further optional solution, the forced sealing structure includes a first extended flange, a second extended flange, a stud and a fastening nut. The first extended flange and the second extended flange are respectively fixed to the tube sheets of different heat exchange modules. The first extended flange and the second extended flange are fixed to each other via the stud and the fastening nut, so as to pull the first extended flange and the second extended flange towards each other.

[0012] As a further alternative, the forced sealing structure simultaneously makes all the tube passes be sealed and connected: the first extended flange is fixed to the upper tube sheet of the first heat exchange module, and the second extended flange is fixed to the lower tube sheet of the last heat exchange module.

[0013] As a further alternative, the forced sealing structure further includes a third extended flange fixed to the tube sheet of the intermediate heat exchange module. The stud is divided into an upper stud and a lower stud. The two ends of the lower stud respectively pass through the first extended flange and the third extended flange and then are screwed into the fastening nut. The two ends of the upper stud respectively pass through the second extended flange and the third extended flange and then are screwed into the fastening nut.

[0014] As a further alternative, the forced sealing structure only makes some of the tube passes be sealed and connected simultaneously: the first extended flange is fixed to the tube sheet of the first or the last heat exchange module, and the second extended flange is fixed to the tube sheet of the middle heat exchange module.

[0015] As a further alternative, the forced sealing structure further includes a platform steel structure fixed to the external reinforced concrete foundation. The two ends of some studs respectively pass through the first extended flange and the platform steel structure and then are screwed into the fastening nut. The two ends of the other part of the studs respectively pass through the second extended flange and the platform steel structure and then are screwed into the fastening nut.

[0016] As a further alternative, the connecting pipe serves as the forced sealing structure. The connecting pipe is a bent pipe, and the end of the bent pipe is provided with an adapter flange, a short stud and a nut locking member. The connecting pipes communicating between different heat exchange modules are mutually connected and fixed via the short stud and the nut locking member.

[0017] As a further alternative, the connecting pipes of non-adjacent and mutually separated heat exchange modules are connected to each other.

[0018] As a further alternative, the shell diameters of adjacent heat exchange modules are the same, and the intermediate header box between the adjacent heat exchange modules is a straight cylinder; or the shell diameters of adjacent heat exchange modules are different, and the intermediate header box between the adjacent heat exchange modules is a frustum cylinder.

[0019] As a further alternative, the heat exchange module further includes baffles, spacers and tie rods located in the shell side. Multiple baffles are arranged in parallel and are provided with tube holes for the heat exchange tubes to pass through. The end of the tie rod is fixed to the tube sheet and passes through multiple baffles. The spacer is sleeved outside the tie rod and axially abuts against the baffle, so as to limit the distance between different baffles.

[0020] The beneficial effects of the present invention:

[0021] A multi-connected heat exchanger with integral forced sealing according to the present invention has the following advantages compared with the prior art:

[0022] (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 in the middle sections, lightens the overall weight of the heat exchanger and its supporting structure, saves equipment space and construction costs.

[0023] (2) During the operation of the heat exchanger, the temperature of the tube bundle and the shell is higher than that of the fasteners around the shell. The thermal elongation of the shell is slightly longer than that of the fasteners made of the same type of steel, making the connection ports of each section fit more closely together to strengthen the seal and improve the overall strength and stiffness of the heat exchanger.

[0024] (3) The overall forced seal can be installed on-site at the device. The segmented structure of the heat exchangers connected in series can be transported in sections, which is convenient for safe and efficient transportation and reduces transportation costs.

[0025] (4) The overall forced seal can be installed on-site at the device. The segmented structure can be hoisted in sections, which is convenient for on-site construction organization and reduces hoisting costs.

[0026] (5) It saves equipment space and construction costs. The heat exchanger has the characteristics of simple structure, easy installation and disassembly, and long service life.

[0027] (6) The multi-connected heat exchanger with overall forced seal is especially suitable for multi-section heat exchange conditions with high temperature, low pressure, large diameter, extra-long and extra-heavy tube-side fluids. It is suitable for both vertical and horizontal multi-connected heat exchangers and has the characteristics of simple structure, easy installation and disassembly, and long service life. Description of the Drawings

[0028] Figure 1 It is a schematic structural diagram of a heat exchanger in the prior art.

[0029] Figure 2 It is a schematic structural diagram of Embodiment 1 of a multi-connected heat exchanger with overall forced seal in the embodiment.

[0030] Figure 3 It is a schematic structural diagram of Embodiment 2 of a multi-connected heat exchanger with overall forced seal in the embodiment.

[0031] Figure 4 It is a schematic structural diagram of Embodiment 3 of a multi-connected heat exchanger with overall forced seal in the embodiment.

[0032] Figure 5 It is a schematic structural diagram of Embodiment 4 of a multi-connected heat exchanger with overall forced seal in the embodiment.

[0033] Figure 6 It is a schematic structural diagram of Embodiment 5 of a multi-connected heat exchanger with overall forced seal in the embodiment.

[0034] Figure 7Schematic structural diagram of Embodiment Six of an integrally forced-sealed multi-connected heat exchanger in the embodiments. Specific embodiments

[0035] The present invention will be described in detail below in conjunction with specific embodiments and the accompanying drawings.

[0036] One specific embodiment of an integrally forced-sealed multi-connected heat exchanger of the present invention is as Figure 2 shown, including multiple heat exchange modules connected in series in sequence. In practice, the number of heat exchange modules can be changed to other values according to needs. Figure 2 Four heat exchange modules are schematically shown, 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 each heat exchange module are basically the same. Figure 2 Only the internal structure of the third heat exchange module 3 is specifically schematically shown herein, and the other heat exchange modules are briefly schematically shown. The third heat exchange module 3 includes a shell 14 and a tube bundle located inside the shell 14. The tube bundle includes multiple heat exchange tubes 11 and two tube sheets 12. The two tube sheets 12 are fixed at both ends of the shell 14 to jointly enclose a shell side. The multiple heat exchange tubes 11 are arranged in parallel in the shell side and their two ends are fixed to the corresponding tube sheets 12. A nozzle 141 for flowing a cooling medium is provided on the side wall of the shell 14 to communicate with the shell side. The heat exchange module further includes baffle plates 10, spacer tubes, and tie rods located in the shell side. Multiple baffle plates 10 are arranged in parallel and are provided with 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 multiple baffle plates 10. The spacer tubes are sleeved outside the tie rods and axially abut against the baffle plates 10, thereby restricting the distance between different baffle plates 10. An intermediate header is provided between adjacent heat exchange modules, and end headers are provided at both ends of the overall heat exchange module. For example, a conical lower end header 5 is provided at the lower end of the first heat exchange module 4, a first intermediate header 6 is provided between the first heat exchange module 1 and the second heat exchange module 2, a second intermediate header 7 is provided between the second heat exchange module 2 and the third heat exchange module 3, a third intermediate header 8 is provided between the third heat exchange module 3 and the fourth heat exchange module 4, and a top header 9 is provided at the top of the fourth heat exchange module 4. It can be seen that the shell diameters of adjacent heat exchange modules can be the same or different. If the shell diameters are the same, the intermediate header between the adjacent heat exchange modules is a straight cylinder; if the shell diameters are different, the intermediate header between the adjacent heat exchange modules is a frustum cylinder. The lower end header 5, the heat exchange tubes of the first heat exchange module 1, the first intermediate header 6, the heat exchange tubes of the second heat exchange module 2, the second intermediate header 7, the heat exchange tubes of the third heat exchange module 3, the third intermediate header 8, the heat exchange tubes of the fourth heat exchange module 4, and the upper end header 9 are sequentially communicated, thus forming multiple tube passes. The overall multiple heat exchange modules are supported on a skirt support 13. As a vertical multi-connected heat exchanger, it can actually be changed to a horizontal multi-connected heat exchanger arranged horizontally.

[0037] In this embodiment, a forced sealing structure is provided outside the heat exchange module, which simultaneously seals and connects multiple successive tube passes. Specifically: The forced sealing structure includes a first extended flange 15, a second extended flange 16, a stud bolt, and a fastening nut 17. The first extended flange 15 and the second extended flange 16 are respectively fixed to the tube sheets of different heat exchange modules. Figure 2 In the forced sealing structure, all tube passes are simultaneously sealed and connected. The first extended flange is fixed to the upper tube sheet of the first heat exchange module 1 at the head, and the second extended flange 16 is fixed to the lower tube sheet of the fourth heat exchange module 4 at the end. The first extended flange 16 and the second extended flange 17 are fixed to each other via the stud bolt and the fastening nut 17, thereby pulling the first extended flange 15 and the second extended flange 16 towards each other. Multiple groups of stud bolts and fastening nuts 17 are arranged circumferentially around the heat exchanger.

[0038] As can be seen from the above, there is no direct separate flange bolt forced sealing structure for the connection of the tube passes between adjacent two sections of heat exchange modules. Instead, the connection of the tube passes between all sections of heat exchange modules is integrally tightened and sealed through the forced sealing structure installed around the heat exchanger. This avoids the large flanges for separate connection and sealing in the middle sections, reduces the overall weight of the heat exchanger and its supporting structure, saves equipment space and construction costs, and the heat exchanger has the characteristics of simple overall structure, convenient installation and disassembly, and long service life. A set of standard stud bolts and fastening nuts 17 realizes the forced connection of the tube passes and shell passes of all sections of heat exchange modules, which is efficient.

[0039] The above stud bolts are stud bolts without shoulders in the middle or stud bolts with shoulders in the middle. The shoulders are used to abut against the corresponding extended flanges. Loosening the nut at one end of the stud bolt does not affect the fastening of the nut at the other end of the stud bolt.

[0040] Embodiment 2

[0041] The second specific embodiment of a multi-connected heat exchanger with integral forced sealing according to the present invention. The main technical solution of this embodiment is the same as that of Embodiment 1. For the features not explained in this embodiment, the explanations in Embodiment 1 are adopted and will not be elaborated here. The difference between this embodiment and Embodiment 1 is as follows. Figure 3As shown, the forced sealing structure only seals and connects part of the tube side simultaneously: The first extension flange 15 is fixed to the upper tube sheet of the first heat exchange module 1 at the head, 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 stud bolts and fastening nuts 19 realize the forced connection of the tube sides of the first heat exchange module 1, the second heat exchange module 2, and the third heat exchange module 3. As for the tube side of the fourth heat exchange module 4, a traditional connection method can be adopted, that is, a combined and compatible mode of traditional and this innovation. This embodiment mainly shows that only the tube sides of some heat exchange modules adopt an integral forced sealing structure. Similarly, it can be changed to that the first extension flange is fixed to the lower tube sheet of the fourth heat exchange module 4 at the end, and the second extension flange is changed to be fixed to the tube sheet of the second heat exchange module / third heat exchange module, and then they are tightened by stud bolts and fastening nuts to also realize the integral forced sealing of part of the tube side.

[0042] Embodiment 3

[0043] The third specific embodiment of a multi-connected heat exchanger with integral forced sealing of the present invention. The main technical solution of this embodiment is the same as that of Embodiment 1. For the features not explained in this embodiment, the explanations in Embodiment 1 are adopted and will not be elaborated here. The difference between this embodiment and Embodiment 1 is that, as Figure 4 shown, the connections of the tube sides between all sections of heat exchange modules are also all integrally fastened and sealed through the forced sealing structure installed around the heat exchanger. The forced sealing structure further includes a third extension flange 18 fixed to the tube sheet of the intermediate heat exchange module. The stud bolts are divided into upper stud bolts 20 and lower stud bolts 21. The two ends of the lower stud bolt 21 respectively pass through the first extension flange 15 and the third extension flange 18 and then are screwed into the fastening nuts for locking. The two ends of the upper stud bolt 20 respectively pass through the second extension flange 16 and the third extension flange 18 and then are screwed into the fastening nuts for locking.

[0044] This embodiment simultaneously uses two sets of stud bolts with different specifications, namely the upper stud bolts 20 and the lower stud bolts 21. The two sets of stud bolts are alternately installed at intervals along the flange circumference. While realizing the forced connection of the tube sides and shell sides of all sections of heat exchange modules, after unsealing between the upper sections of heat exchange modules, the sealing between the lower sections of heat exchange modules can continue to be maintained, or vice versa. While unsealing between the lower sections of heat exchange modules, the sealing between the upper sections of heat exchange modules can be maintained.

[0045] Of course, only using one set of stud bolts with the specification of the upper stud bolts 20 or the lower stud bolts 21 can also realize the forced connection of the tube sides and shell sides of multiple sections of heat exchange modules, which is equivalent to changing to the structure of Embodiment 2.

[0046] Embodiment 4

[0047] The fourth specific embodiment of the multi-connected heat exchanger of the present invention is a whole forced seal. The main technical scheme 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 5 As shown, the forced sealing structure also includes a platform steel structure 22, which is fixed on an external steel slow-setting soil foundation 25, and both ends of a part of the studs 24 pass through the first extension flange 15 and the platform steel structure 22 and are screwed into the fastening nuts, and both ends of another part of the studs 23 pass through the third extension flange 18 and the platform steel structure 22 and are screwed into the 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 sealed as a whole.

[0048] Of course, in practice, the position of the third extension flange 18 can be changed to the tube sheet fixed to the fourth heat exchange module 4 in Example 1, so that the tubes of the four heat exchange modules are sealed by the forced sealing structure. Of course, in combination with the structure of Example 3, an extension flange is set on the lower tube sheet of the fourth heat exchange module 4, and the extension flange is fixed with the third extension flange 18, the platform steel structure 22 or the first extension flange 15 by studs to achieve overall sealing. This embodiment is intended to illustrate that the platform steel structure 22 can be added to provide a more secure support for the extension flange, and the overall strength and stability are improved.

[0049] Example 5

[0050] The fifth specific embodiment of the multi-connected heat exchanger of the present invention with integral forced sealing is the same 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 connecting pipe of the side wall of the tube shell connected to the shell side also serves as the forced sealing structure. The connecting pipe is a bent pipe 26, and the end of the bent pipe 26 is provided with a connecting flange 27, a short stud and a nut locking piece 28. The connecting pipes connected to different heat exchange modules are connected and fixed to each other via short studs and nut locking pieces 28.

[0051] From the overall perspective, the tension of the shell-side pipe of the upper heat exchange module plays an auxiliary role in the sealing of the tube side and shell side of the lower heat exchange module. After disassembling and inspecting the upper forced connection, it will not affect the lower forced connection. It can also save the double-headed long studs and their nut fasteners.

[0052] Certainly, the takeover forced seal of this embodiment can coexist with the double-headed tie rods and platform steel structures of other embodiments to achieve forced seal in multiple aspects. The seal of the tube side between two heat exchange modules is achieved through self-tightening seal during operation due to thermal expansion. The platform steel structure and the rigid takeover structure are used together to limit the thermal elongation of the heat exchanger, and the displacement load is converted into a sealing load to compress the gasket.

[0053] Embodiment 6

[0054] This is the sixth specific embodiment of an integrally forced-sealed multi-connected heat exchanger of the present invention. The main technical solution of this embodiment is the same as that of Embodiment 5. For the features not explained in this embodiment, the explanations in Embodiment 5 are adopted and will not be elaborated here. The difference between this embodiment and Embodiment 5 is that, as Figure 6 shown, the takeovers of non-adjacent and mutually separated heat exchange modules are connected to each other. For example, the takeover 30 between the first heat exchange module 1 and the third heat exchange module 3, and the takeover 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 the other forced connection is not affected after disassembling and inspecting one of the forced connections. At the same time, 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 are also realized, and the double-headed long studs and their nut fasteners are also saved.

[0055] In the description of the present invention, unless otherwise clearly specified and defined, the terms "installation", "connection", "connection", and "fixation" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0056] The standard parts used in the present invention can all be purchased from the market. The special-shaped parts can be customized according to the description in the specification and the drawings. The specific connection methods of each part all adopt conventional means such as bolts, rivets, and welding in the existing technology. The machines, 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 elaborated here.

[0057] Although embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

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

Claims

1. A multi-connected heat exchanger with integral forced sealing, characterized in that: It includes multiple heat exchange modules connected in series in sequence. Each heat exchange module includes a shell and a tube bundle located inside the shell. The tube bundle includes multiple heat exchange tubes and two tube sheets. The two tube sheets are fixed at both ends of the shell to jointly enclose a shell side. The multiple heat exchange tubes are arranged in parallel in the shell side and their two ends are fixed to the corresponding tube sheets. A nozzle communicating with the shell side is provided on the side wall of the shell; an intermediate header tank is provided between adjacent heat exchange modules, and end header tanks are provided at both ends of the overall heat exchange module. The end header tanks, the heat exchange tubes of each heat exchange module, and the intermediate header tank are connected and communicated to form multiple tube passes; a forced sealing structure is arranged outside the heat exchange module, which simultaneously makes the multiple tube passes in sequence be hermetically connected; The forced sealing structure includes a first extended flange, a second extended flange, a stud, and a fastening nut. The first extended flange and the second extended flange are respectively fixed to the tube sheets of different heat exchange modules. The first extended flange and the second extended flange are fixed to each other via the stud and the fastening nut, so as to tightly pull the first extended flange and the second extended flange towards each other; The forced sealing structure further includes a platform steel structure, which is fixed to the external reinforced concrete foundation. Both ends of some studs respectively pass through the first extended flange and the platform steel structure and then are screwed into the fastening nut, and both ends of the other part of the studs respectively pass through the second extended flange and the platform steel structure and then are screwed into the fastening nut.

2. The multi-connected heat exchanger with integral forced sealing according to claim 1, characterized in that: The forced sealing structure simultaneously makes all the tube passes be hermetically connected: the first extended flange is fixed to the upper tube sheet of the first heat exchange module, and the second extended flange is fixed to the lower tube sheet of the last heat exchange module.

3. The multi-connected heat exchanger with integral forced sealing according to claim 2, characterized in that: The forced sealing structure further includes a third extended flange fixed to the tube sheet of the intermediate heat exchange module. The stud is divided into an upper stud and a lower stud. Both ends of the lower stud respectively pass through the first extended flange and the third extended flange and then are screwed into the fastening nut, and both ends of the upper stud respectively pass through the second extended flange and the third extended flange and then are screwed into the fastening nut.

4. The multi-connected heat exchanger with integral forced sealing according to claim 1, characterized in that: The forced sealing structure only makes some of the tube passes be hermetically connected simultaneously: the first extended flange is fixed to the tube sheet of the first or last heat exchange module, and the second extended flange is fixed to the tube sheet of the intermediate heat exchange module.

5. The multi-connected heat exchanger with integral forced seal according to claim 1, characterized in that: The nozzle also serves as the forced sealing structure. The nozzle is a bent pipe, and an adapter flange, a short stud, and a nut locking member are provided at the end of the bent pipe. The nozzles of different heat exchange modules communicating with each other are connected and fixed to each other via the short stud and the nut locking member.

6. The multi - connection heat exchanger with integral forced sealing according to claim 5, characterized in that: The nozzles of non-adjacent and mutually separated heat exchange modules are connected to each other.

7. The multi-connected heat exchanger with integral forced sealing according to claim 1, characterized in that: The shell diameters of adjacent heat exchange modules are the same, and the intermediate header tank between the adjacent heat exchange modules is a straight cylinder; or the shell diameters of adjacent heat exchange modules are different, and the intermediate header tank between the adjacent heat exchange modules is a frustum cylinder.

8. The multi-connected heat exchanger with integral forced sealing according to claim 1, characterized in that: The heat exchange module further includes baffle plates, spacer pipes, and tie rods located in the shell side. Multiple baffle plates are arranged in parallel and are provided with 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 baffle plates. The spacer pipes are sleeved outside the tie rods and axially abut against the baffle plates, so as to limit the distance between different baffle plates.

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