Tandem pipe reactor with jacketed pipe provided with thin-wall expansion joints

Abstract

The utility model relates to the technical field of petrochemical equipment, in particular to a serial pipe reactor with jacketed pipes provided with thin-wall expansion joints, which comprises a plurality of straight jacketed pipes and a plurality of bent pipes, each straight jacketed pipe comprises an inner pipe and an outer pipe, and the inner pipe is arranged in the outer pipe in a penetrating manner to form an annular straight jacketed flow channel; the inner pipes of the plurality of straight sleeves are connected in series through a bent pipe to form a medium flow channel for conveying and reacting reaction materials, and the straight jacket flow channels of the plurality of straight sleeves are connected in series to form a cooling flow channel for conveying a cooling medium; local sections of an outer pipe of the straight casing pipe are arranged to be expansion joints, each expansion joint is of a thin-wall corrugated pipe structure, and reinforcing rings are arranged on the outer side and / or the inner side of the bent position of each expansion joint. Compared with the prior art, the expansion joint adopts a thin-wall structure, so that the expansion joint is easier to deform and absorbs thermal elongation stress; the thin-wall expansion joint is easier to weld thoroughly, various welding means such as manual electric arc welding, argon arc welding and automatic submerged arc welding are also suitable for being flexibly used, and the work efficiency is improved; the usage amount of steel is saved, consumables are reduced, and the cost is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of petrochemical equipment, in particular to a series tube reactor with a thin-walled expansion joint in a jacketed pipe. Background Technique

[0002] In the prior art, polyolefins (such as polypropylene and polyethylene) are the varieties with the largest production and consumption in general synthetic resins. The common production technologies of polyolefins usually include three types: slurry process, gas phase process and solution process. The so-called slurry process (Slurry Process), also known as slurry method or solvent process method, is the earliest process technology used for producing polypropylene in the world. The slurry process technology is the main method for producing HDPE. The production process is as follows: propylene or ethylene is mixed with a hydrocarbon solvent, and the produced polymer is suspended in the solvent. The industrial application time of the slurry process is earlier, the process technology is mature, and the pressure and temperature are lower during the production process. According to the reactor form, the reaction equipment used in the slurry process can be divided into two types: stirred tank reactor and series tube reactor.

[0003] In the prior art, a common series tube reactor includes several straight sleeve pipes set according to production capacity, as well as corresponding jacket connecting pipes, elbows, mounting supports, connecting beams, etc. The straight sleeve pipe includes an inner pipe and an outer pipe. The ends of the elbows are connected in series with the ends of the inner pipe in sequence to form a communicating flow channel for the transportation and reaction of reaction materials. Since heat is generated during the polymerization reaction, a jacket flow channel is formed between the inner pipe and the outer pipe of the straight sleeve pipe. The jacket connecting pipe is connected to the outer pipe to connect the jacket flow channels into a communicating flow channel for transporting the cooling medium. The reaction heat is carried away by the cooling medium in the jacket flow channel. A corrugated expansion joint, a mounting support and a support beam seat are arranged on the outer pipe of the straight sleeve pipe. The connecting beam is connected to the support beam seat by bolts to combine the straight sleeve pipes into a three-dimensional framework. Since the series tube reactor is supported by multiple bases, that is, each straight sleeve pipe is provided with a corresponding mounting support, errors in the length, axial position, orientation, elevation, spacing, etc. of the straight sleeve pipes, as well as many factors such as the parallelism of the straight sleeve pipes, the perpendicularity of the flanges, and the manufacturing errors of the elbows, will all affect the installation and sealing performance of the loop pipe at the same time; and the series tube reactor is made of low-temperature steel, and has high requirements for manufacturing, welding and heat treatment. In order to make the material flow smoothly in the straight sleeve pipe, the inner wall of the inner pipe must be polished multiple times to be close to a mirror surface to prevent the reactants from sticking to the wall and causing explosive polymerization.

[0004] For example, the structure of a series tube reactor for producing 300,000 tons / year of polypropylene is as Figure 1As shown in the figure, it mainly consists of six straight sleeves (the first straight sleeve R1, the second straight sleeve R2, the third straight sleeve R3, the fourth straight sleeve R4, the fifth straight sleeve R5, and the sixth straight sleeve R6) each with a length of 50m and an outer diameter of φ609.6×16mm, five 180° large elbows (the first elbow A1, the second elbow A2, the third elbow A3, and two elbows at the bottom), and one 90° elbow connected in sequence to form a circular whole. And through five outer elbows connected to the outer pipe at the inner elbow, it is located on a relatively high platform foundation. An axial flow pump is provided at the inner elbow at the bottom of the string of pipes. The reaction material enters the string reactor from the reaction material inlet 1A, is stirred and circulated in the pipe driven by the axial flow pump, and reacts under the action of the catalyst to form slurry polypropylene, which is discharged from the reaction material outlet 1B and enters the granulation system; the cooling medium enters from the cooling medium inlet of the jacket flow channel and flows out from the cooling medium outlet of the jacket flow channel. Six mounting supports are located at the lower parts of the straight sleeves R1, R2, R3, R4, R5, and R6. There are five jacket connecting pipes connecting the jackets to each other. The cooling water in the jacket takes away the heat released by the reaction in the inner pipe through the partition wall to maintain the normal operation of the reaction process. This string reactor is located on a platform foundation 11m high, and the whole equipment weighs about 210 tons. In order to coordinate the difference in thermal expansion displacement caused by different temperatures between the inner pipe and the outer pipe, expansion joints are attached to the jacket; expansion joints, support beam seats and supports are also attached to the jacket. Adjacent jackets are connected by steel profiles to form eight space platforms.

[0005] With the shortage of petroleum resources, in order to meet the huge demand and development of the market for ethylene special materials, new and more stringent requirements have been put forward for the structure, production capacity and quality of the string reactor equipment. With the further expansion of the production capacity scale, the body structure of the string reactor in the above-mentioned existing technology is getting higher and higher, and the latitude of the location where the reactor is installed and operated is also getting higher and higher. Since the straight sleeves adopt an integral slender vertical structure, when these factors are combined, the following deficiencies will occur:

[0006] The difference in thermal expansion and contraction displacement between the inner pipe and the outer pipe of the string reactor increases. When relying solely on the traditional corrugated expansion joint structure to absorb and buffer this difference, the best effect cannot be achieved. Even more wave numbers are required, the manufacturing accuracy is getting lower and lower, and its operating function is getting more and more difficult to guarantee.

[0007] Below, the existing technology document [1] puts forward the problems that need attention in the analysis and design of thick-walled expansion joints by comparing the differences in the calculation methods of thick-walled expansion joints in GB / T 16749 and foreign relevant standards. At present, there is a certain research on the analysis and calculation of the expansion joints of the string reactor, but it is not specific and in-depth enough.

[0008] In the design of conventional pressure-bearing equipment, the design of pipeline expansion joints has the standard GB / T 12777—2019 [2], usually with a relatively thin wall thickness. The design of the corrugated expansion joint for pressure vessels has the standard GB / T 16749—2018 [3] , usually with a relatively thick wall thickness. The string-tube reactor combines the characteristics of a pressure vessel and a pipeline and is a special equipment with multiple corrugated expansion joints welded. Therefore, it is not advisable to continue along the traditional technical route and still design it according to the corrugated expansion joint for pressure vessels. The characteristics of the expansion joint of the loop reactor should be studied, including the overall characteristics of the expansion joint and the characteristics of each corrugation, stress and deformation conditions, and explore the optimized design of the expansion joints of the jacketed pipe and the connecting pipe, especially the design and application of the thin-walled expansion joint of the pipeline.

[0009] [1] Chu Jianwei. Discussion on the stress analysis problem of the national standard thick-walled expansion joint [J]. Petrochemical Equipment, 2023, 52(04): 49-52

[0010] [2] State Administration for Market Regulation, Standardization Administration of the People's Republic of China. General technical conditions for metal bellows expansion joints: GB / T 12777-2019 [S]. Beijing: China Standards Press, 2019

[0011] [3] State Administration for Market Regulation, Standardization Administration of the People's Republic of China. Corrugated expansion joints for pressure vessels: GB / T16749-2018 [S]. Beijing: China Standards Press, 2018

[0012] To sum up, in order to quickly adapt to the current market environment with a large demand for string-tube reactors with high production capacity and large structure in the new construction and expansion of petrochemical industry, to meet the requirements of capacity increase, energy expansion, upgrading of traditional string-tube reactors, and high production capacity with a polypropylene production capacity of more than 600,000 tons per year, developing a new structure of high-production-capacity string-tube reactors has profound and significant industrial and economic significance. Summary of the Invention

[0013] Aiming at all or part of the above technical problems existing in the prior art, the utility model provides a string-tube reactor with a jacketed pipe and a thin-walled expansion joint.

[0014] To achieve the above object, the utility model provides the following technical solutions:

[0015] Provide a string-tube reactor with a jacketed pipe and a thin-walled expansion joint, including multiple straight pipes and multiple bent pipes. Each straight pipe includes an inner pipe and an outer pipe, and the inner pipe passes through the outer pipe to form an annular straight jacket flow channel; the inner pipes of multiple straight pipes are connected in series via bent pipes to form a medium flow channel for conveying reaction materials and carrying out reactions, while the straight jacket flow channels of multiple straight pipes are connected in series to form a cooling flow channel for conveying cooling medium; a local section of the outer pipe of the straight pipe is set as an expansion joint, and its characteristics are: the expansion joint is a single-layer or multi-layer thin-walled corrugated pipe structure with a wall thickness less than 2 mm for each layer, and a reinforcing ring is arranged on the outer side and / or the inner side of the bending part of the expansion joint.

[0016] As a further optional technical solution, the string tube reactor further includes a plurality of jacket connecting pipes; sealing structures are provided at both ends of the straight jacket flow channel to seal the two ports of the straight jacket flow channel;

[0017] The straight jacket flow channels of the plurality of straight sleeve pipes are connected in series in the following way: the elbow is a single-layer pipe, and both ends of the jacket connecting pipe are connected to the outer pipe side walls of different straight sleeve pipes and communicate with the corresponding straight jacket flow channels, so that the straight jacket flow channels of two adjacent straight sleeve pipes are directly communicated through the jacket connecting pipe;

[0018] Alternatively, each elbow is a double-layer pipe including an outer elbow and an inner elbow, and the outer elbow is sleeved outside the inner elbow to form an annular bent jacket flow channel; the inner pipes of different straight sleeve pipes are connected in series through the inner elbows to form the medium flow channel; sealing structures are respectively provided at both ends of the bent jacket flow channel to seal the two ports of the bent jacket flow channel; one end of the jacket connecting pipe is connected to the outer pipe side wall of the straight sleeve pipe and communicates with the straight jacket flow channel, and the other end of the jacket connecting pipe is connected to the outer elbow side wall of the elbow and communicates with the bent jacket flow channel, so that the straight jacket flow channels of two adjacent straight sleeve pipes are communicated through the jacket connecting pipe and the bent jacket flow channel.

[0019] As a further optional technical solution, the expansion joint is also provided on the jacket connecting pipe and / or the outer elbow.

[0020] As a further optional technical solution, mounting supports are arranged on the outer wall of the outer pipe of each straight sleeve pipe, so that the straight sleeve pipe is divided into an upper pipe section of the straight sleeve pipe and a lower pipe section of the straight sleeve pipe, and the expansion joints are provided on both the upper pipe section of the straight sleeve pipe and the lower pipe section of the straight sleeve pipe.

[0021] As a further optional technical solution, the waveform of the expansion joint includes but is not limited to Ω shape and a U-shaped structure with a closed end.

[0022] As a further optional technical solution, leakage detection holes are provided at the connection between the waveform of the expansion joint and the end pipe.

[0023] As a further optional technical solution, the expansion joint is an integrally formed structure without weld connection between waveforms; or the expansion joint is formed by welding a plurality of waveforms in sequence.

[0024] As a further optional technical solution, guide protection devices are uniformly arranged on the outer periphery of the waveform of the expansion joint, and the guide protection devices include a plurality of tie rods, a ring plate fixed to the outer pipe, and nuts for locking the tie rods to the ring plate.

[0025] As a further optional technical solution, the outer strengthening ring located on the outside is an integral ring structure, and / or the inner strengthening ring located on the inside is a split group welding structure.

[0026] As a further optional technical solution, a backing plate is provided in the straight jacket flow channel, and the backing plate is assembled and welded to the outer wall of the inner pipe or to the inner walls at both ends of the expansion joint.

[0027] Advantages of the present utility model:

[0028] A series tube reactor with a thin-walled expansion joint of the present utility model has the following advantages compared with the prior art: The expansion joint adopts a thin-walled structure, which is more likely to deform and absorb thermal elongation stress; the thin-walled expansion joint is easier to penetrate by welding and is also suitable for flexible use of various welding methods such as manual arc welding, argon arc welding, and submerged arc automatic welding, improving work efficiency; it saves the usage amount of steel, reduces consumables, and lowers costs.

[0029] Furthermore, a reinforcing ring is provided at the expansion joint to protect the expansion joint. Description of the drawings

[0030] Figure 1 It is a schematic diagram of an existing series tube reactor.

[0031] Figure 2 It is a schematic structural diagram of Embodiment 1 of a single straight sleeve of the series tube reactor of the present utility model.

[0032] Figure 3 It is a schematic structural diagram of Embodiment 2 of a single straight sleeve of the series tube reactor of the present utility model.

[0033] Figure 4 It is a schematic structural diagram of Embodiment 3 of a single straight sleeve of the series tube reactor of the present utility model.

[0034] Figure 5 It is a schematic diagram of an embodiment of the straight sleeve of the series tube reactor of the present utility model with an expansion joint, showing that the reinforcing ring is located outside the expansion joint.

[0035] Figure 6 It is a schematic diagram of another embodiment of the straight sleeve of the series tube reactor of the present utility model with an expansion joint, showing that the reinforcing ring is located inside the expansion joint.

[0036] Figure 7 It is a schematic diagram of an embodiment of the straight sleeve of the series tube reactor of the present utility model with an expansion joint, showing that the reinforcing ring is located outside and inside the expansion joint.

[0037] Figure 8 It is a schematic diagram of the reinforcing ring.

[0038] Reference numerals:

[0039] Inner tube 1, outer tube 2, straight jacket flow channel 3, expansion joint 4, reinforcing ring 5, installation support 6, upper section of straight sleeve 7, lower section of straight sleeve 8, backing plate 9, tie rod 10, ring plate 11, nut 12. Specific implementation mode

[0040] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present utility model. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0041] The series tube reactor of this embodiment, as Figures 1 to 7 shown, includes six straight sleeves and multiple bent tubes. The reaction material enters the series tube reactor from the reaction material inlet 1A and discharges from the reaction material outlet 1B. Each straight sleeve includes an inner tube 1 and an outer tube 2, and the inner tube 1 is inserted through the outer tube 2 to form an annular straight jacket flow channel 3. The inner tubes 1 of multiple straight sleeves are connected in series via bent tubes to form a medium flow channel for conveying and reacting the reaction material, while the straight jacket flow channels 3 of multiple straight sleeves are connected in series to form a cooling flow channel for conveying the cooling medium.

[0042] This series tube reactor further includes multiple jacket communication pipes; the straight jacket flow channels 3 of multiple straight sleeves are connected in series in the following way: the bent tube is a single-layer tube, and both ends of the jacket communication pipe are connected to the side walls of the outer tubes 2 of different straight sleeves and communicate with the corresponding straight jacket flow channels 3, so that the straight jacket flow channels 3 of adjacent two straight sleeves are directly connected through the jacket communication pipe. This series connection structure is a traditional series connection method. Later, the inventor also designed the bent tube as a double-layer jacket structure, that is, each bent tube is a double-layer tube including an outer elbow and an inner elbow, and the outer elbow is sleeved outside the inner elbow to form an annular bent jacket flow channel; the inner tubes 1 of different straight sleeves are connected in series via the inner elbows to form the medium flow channel; sealing structures are respectively provided at both ends of the straight jacket flow channel 3 and the bent jacket flow channel to seal both ends of the straight jacket flow channel 3 and both ends of the bent jacket flow channel; one end of the jacket communication pipe is connected to the side wall of the outer tube 2 of the straight sleeve and communicates with the straight jacket flow channel 3, and the other end of the jacket communication pipe is connected to the side wall of the outer elbow of the bent tube and communicates with the bent jacket flow channel, so that the straight jacket flow channels 3 of adjacent two straight sleeves are connected through the jacket communication pipe and the bent jacket flow channel. For the structures of the bent sleeve and the jacket communication pipe, reference can be made to the Chinese patent documents with the publication numbers CN219984696U, CN219984695U, and CN219984692U, which will not be elaborated here.

[0043] The above is the basic structure of the existing series tube reactor, and the series tube reactor of this embodiment also has these bases. As an improvement:

[0044] The local section of the outer pipe of the straight sleeve is set as an expansion joint 4. The expansion joint 4 is a single-layer or multi-layer thin-wall corrugated pipe structure with a wall thickness of less than 2 mm for each layer. A reinforcing ring 5 is provided on the outer side and / or inner side of the bending part of the expansion joint 4. As Figure 5 shown, the reinforcing ring 5 is located on the outer side of the expansion joint 4; as Figure 6 shown, the reinforcing ring 5 is located inside the expansion joint 4; as Figure 7 shown, the reinforcing ring 5 is located on the inner side and the outer side of the expansion joint 4.

[0045] Similarly, in practice, the expansion joint may also be provided on the jacket connecting pipe and / or the outer elbow, and it is also a thin-wall corrugated pipe structure.

[0046] An installation support 6 is provided on the outer wall of the outer pipe 2 of each straight sleeve, so as to divide the straight sleeve into an upper pipe section 7 of the straight sleeve and a lower pipe section 8 of the straight sleeve. The expansion joint 4 is provided on both the upper pipe section 7 of the straight sleeve and the lower pipe section 8 of the straight sleeve. Figure 2 As shown, the expansion joint 4 of the upper pipe section 7 of the straight sleeve is arranged near the top position. As Figure 3 shown, the expansion joint 4 of the upper pipe section 7 of the straight sleeve is arranged near the bottom position. As Figure 4 shown, the expansion joints 4 are respectively provided at the top and the bottom of the upper pipe section 7 of the straight sleeve.

[0047] In this embodiment, the waveform of the expansion joint 4 is an Ω-shaped or a U-shaped structure with a closed end, or a combination of these two shapes.

[0048] In practice, a leak detection hole may be provided at the connection between the waveform of the expansion joint 4 and the end pipe, that is, at the end position of the expansion joint. Of course, in practice, the leak detection hole can also be cancelled according to needs.

[0049] In this embodiment, the expansion joint 4 is an integrally formed structure without a weld connection between the waveforms; it is manufactured by inputting high-pressure water into a seamless steel pipe to make multiple sections of the cylindrical body bulge outwards to form waveforms and wave crests; before inputting high-pressure water, a reinforcing ring 5 is provided between multiple sections of the cylindrical body to prevent it from bulging outwards to form wave troughs. The expansion joints of the existing string tube reactors are all thick-walled and all have one or even multiple longitudinal welds. Many of the multi-wave expansion joints of the original string tube reactors also have circumferential welds. Or the expansion joint is still a welded structure, and multiple waveforms are welded together in sequence.

[0050] In this embodiment, a guiding and protecting device is uniformly arranged around the outer periphery of the waveform of the expansion joint 4. The guiding and protecting device includes a plurality of tie rods 10, a ring plate 11 fixed to the outer pipe 2, and a nut 12 for locking the tie rods 10 to the ring plate 11. The enhanced guiding and protecting device has both the traditional protection function of guiding along the axial direction and the new protection function of bearing a certain lateral bending moment, avoiding the additional load on the waveform beyond the medium working conditions.

[0051] The outer reinforcing ring 5 is an integral ring structure. The thin-walled corrugation of the expansion joint 4 is made of seamless steel pipe. The inner reinforcing ring 5 is a split and welded structure. The reinforcing ring 5 is divided into multiple petals. After the corrugated expansion forming, the multiple petals are put in one by one and combined into the whole ring. The ends of the petals can be welded to the adjacent petal ends. Figure 8 After the whole ring is processed, it is then divided into four petals by wire cutting. The two parallel cutting lines shown by the dashed lines are also parallel to the diameter. The assembly sequence is to install a or b first, and then install c or d.

[0052] The straight jacket flow channel 3 is provided with a backing plate 9. The backing plate 9 is welded to the outer wall of the inner pipe 1 or to the inner walls at both ends of the expansion joint 4. A backing plate 9 spanning all the corrugations is arranged in the gap between the expansion joint 4 of the straight sleeve jacket and the inner pipe 1 of the straight sleeve. The backing plate 9 can be welded to the outer wall of the inner pipe 1 or to the inner walls of the rings at both ends of the expansion joint 4, but cannot be welded to both the inner pipe 1 and the rings at both ends of the expansion joint 4 simultaneously, nor can it be welded to the corrugations. The backing plate 9 enables the jacket and the inner pipe 1 to transfer loads when in radial contact, avoiding the corrugations from bearing additional loads outside the medium working conditions.

[0053] In the description of the present invention, obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. The components of the embodiments of the present invention usually described and illustrated herein can be arranged and designed in various different configurations.

[0054] Therefore, the above detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the present invention claimed, but merely represents the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present invention.

[0055] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "middle", "upper", "lower", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the invention product is usually placed during use. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation to the present invention. In addition, the terms "first", "second", etc. are only used for descriptive distinction and cannot be understood as indicating or implying relative importance.

[0056] In the description of the present utility model, it should be noted that unless otherwise clearly defined and limited, the terms "arranged", "connected" and "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection or an integral connection. It may be a mechanical connection or an electrical connection. It may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific situations.

Claims

1. A string tube reactor with a thin-walled expansion joint in a jacketed tube, comprising a plurality of straight tubes and a plurality of bent tubes. Each straight tube includes an inner tube and an outer tube, and the inner tube is inserted through the outer tube to form an annular straight jacket flow channel. The inner tubes of the plurality of straight tubes are connected in series via the bent tubes to form a medium flow channel for conveying and reacting reaction materials, while the straight jacket flow channels of the plurality of straight tubes are connected in series to form a cooling flow channel for conveying a cooling medium. A partial section of the outer tube of the straight tube is provided as an expansion joint, and the characteristics are as follows: The expansion joint is a single-layer or multi-layer thin-wall corrugated pipe structure with a wall thickness of less than 2 mm for each layer. A reinforcing ring is provided on the outer side and / or inner side of the bent portion of the expansion joint.

2. The series tube reactor with a jacketed tube and a thin-walled expansion joint according to claim 1, characterized in that: The string tube reactor further includes a plurality of jacket connecting pipes; sealing structures are provided at both ends of the straight jacket flow channel to seal the two ports of the straight jacket flow channel. The straight jacket flow channels of the plurality of straight sleeve pipes are connected in series in the following way: the bent pipe is a single-layer pipe, and both ends of the jacket connecting pipe are connected to the outer pipe side walls of different straight sleeve pipes and communicate with the corresponding straight jacket flow channels, so that the straight jacket flow channels of two adjacent straight sleeve pipes are directly communicated through the jacket connecting pipe. Alternatively, each bent pipe is a double-layer pipe including an outer elbow and an inner elbow, and the outer elbow is sleeved outside the inner elbow to form an annular bent jacket flow channel; the inner pipes of different straight sleeve pipes are connected in series to form the medium flow channel; sealing structures are respectively provided at both ends of the bent jacket flow channel to seal the two ports of the bent jacket flow channel; one end of the jacket connecting pipe is connected to the outer pipe side wall of the straight sleeve pipe and communicates with the straight jacket flow channel, and the other end of the jacket connecting pipe is connected to the outer elbow side wall of the bent pipe and communicates with the bent jacket flow channel, so that the straight jacket flow channels of two adjacent straight sleeve pipes are communicated through the jacket connecting pipe and the bent jacket flow channel.

3. A series tube reactor with a jacketed tube and a thin-walled expansion joint according to claim 2, characterized in that: The expansion joint is also provided on the jacket connecting pipe and / or the outer elbow.

4. A series tube reactor with a thin-walled expansion joint in the jacketed tube according to claim 1, characterized in that: Mounting supports are provided on the outer wall of the outer pipe of each straight sleeve pipe, so that the straight sleeve pipe is divided into an upper pipe section and a lower pipe section of the straight sleeve pipe, and the expansion joint is provided on both the upper pipe section and the lower pipe section of the straight sleeve pipe.

5. A string tube reactor with a jacketed tube and a thin-walled expansion joint according to claim 1, characterized in that: The waveforms of the expansion joint include but are not limited to Ω-shaped and closed U-shaped structures.

6. A series tube reactor with a jacketed tube and a thin-walled expansion joint according to claim 1, characterized in that: Leak detection holes are provided at the connection between the waveform of the expansion joint and the end pipe.

7. A string tube reactor with a jacketed tube and a thin-walled expansion joint according to claim 1, characterized in that: The expansion joint is an integrally formed structure without weld connection between waveforms; or the expansion joint is formed by welding a plurality of waveforms in sequence.

8. A series tube reactor with a jacketed tube and a thin-walled expansion joint according to claim 1, characterized in that: Guide protection devices are uniformly arranged on the outer periphery of the waveform of the expansion joint. The guide protection devices include a plurality of tie rods, a ring plate fixed to the outer pipe, and nuts for locking the tie rods to the ring plate.

9. A string tube reactor with a jacketed tube and a thin-walled expansion joint according to claim 1, characterized in that: The reinforcing ring located on the outer side is an integral ring structure, and / or the reinforcing ring located on the inner side is a split and welded structure.

10. A series tube reactor with a thin-walled expansion joint in the jacketed tube according to claim 1, characterized in that: A backing plate is provided in the straight jacket flow channel, and the backing plate is welded to the outer wall of the inner pipe or to the inner walls at both ends of the expansion joint.

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