Glandless packing type connector with pre-tightening compensation and heat exchanger with same

Abstract

The present application relates to petrochemical equipment technical field, specifically to the packing gland type pipe with pre-tightening compensation and heat exchanger with same, including inner tube, outer tube and sealing assembly, the inner tube is worn in the outer tube, sealing assembly is slidably sealedly connected with the outer wall of the outer tube and the inner tube, sealing assembly includes packing gland, sealing gland, packing and fastener, the inner side of sealing gland and the outer wall surface of the inner tube are provided with accommodating ring cavity, the packing is located in the accommodating ring cavity, the packing gland is connected with the sealing gland and the end of the packing away from the outer tube is compressed; the accommodating ring cavity is provided with an inclined body, the inner side of the sealing gland and the outer wall surface of the inner tube are provided with a snap ring, the snap ring is closely combined with the outer wall of the inner tube, and the end of the packing close to the outer tube is compressed by the snap ring. Compared with the prior art, the snap ring is used to compress the packing, the structure is simple, and assembly is convenient; the packing can be prevented from extruding into the gap between the snap ring and the inner tube, and the long-term sealing effect of the packing is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of petrochemical equipment technology, specifically to a stuffing box nozzle with pre-tightening compensation and a heat exchanger incorporating it. Background Technology

[0002] Heat exchangers are widely used in the chemical and petrochemical industries, serving as indispensable and commonly used process equipment. In recent years, with the development of energy-saving technologies, the recovery of high- and low-temperature heat energy using heat exchangers has brought significant economic benefits. Since the beginning of the 21st century, with the rapid development of large-scale equipment, the use of large heat exchangers has become increasingly widespread and frequent, with increasing technical difficulty and higher reliability requirements. How to ensure heat exchange effects, improve thermal efficiency, and enhance equipment reliability has become a crucial research topic, leading to a proliferation of large heat exchanger technologies for applications under special process conditions.

[0003] Loop reactors are primarily used in the production of polypropylene and polyethylene in the petrochemical industry, and are also commonly found in slurry coolers, butene coolers, and other production equipment in the petrochemical field. In existing technology, a typical loop reactor includes several straight sleeves, corresponding jacketed connecting pipes, elbows, and connecting beams, arranged according to its production capacity. Each pair of straight sleeves is connected in series with two elbows, forming a connecting channel. Because polymerization is exothermic, it generates a large amount of heat. Therefore, the straight sleeves have jacketed channels formed by the inner and outer pipes, and these channels are connected in series through jacketed connecting pipes located at the elbows and connecting to the outer pipes. The cooling medium within the jacketed channels carries away the reactive heat. The outer pipes of the straight sleeves are also equipped with corrugated expansion joints, mounting supports, and support beam seats. The connecting beams are bolted to the support beam seats, connecting the straight sleeves into a three-dimensional frame loop reactor. This makes the loop reactor a multi-foundation support structure, meaning that each straight sleeve is supported by its corresponding mounting support.

[0004] In existing loop reactors, a straight sleeve with displacement buffers is used. The straight sleeve is 50m high. The upper section of the straight sleeve, located above the mounting support, has a three-wavelength corrugated expansion joint type displacement buffer, while the lower section, located below the mounting support, has a one-wavelength corrugated expansion joint type displacement buffer. Both corrugated expansion joint type displacement buffers are mounted on the outer sleeve. The inner sleeve is connected to flanges and elbows at both ends. However, when the height of the straight sleeve exceeds 50m, the displacement difference due to thermal expansion and contraction between the inner and outer sleeves increases. If only the corrugated expansion joint type displacement buffers of the above structure are used to absorb and buffer this displacement difference, the required wavelength will gradually increase. For example, increasing the wave number to four or more can lead to a decrease in overall manufacturing precision and unevenness between different waveforms, resulting in frequent defective products. Furthermore, the fatigue strength is also poor, and the lifespan is shorter, making it increasingly difficult to guarantee operational efficiency. Moreover, the thickness of the weld between the waveform expansion joint type displacement buffer and the outer shell of the tube is subject to certain requirements; it cannot be too thin, as increased thickness leads to increased costs. Therefore, this single waveform expansion joint type displacement buffer is particularly unsuitable for large-scale loop reactors with straight sleeves longer than 50m. Referring to the applicant's previous research, such as the Chinese patent document CN102068951B, which discloses a loop reactor with displacement buffer, a displacement buffer is provided between the inner and outer tubes of the straight sleeve to absorb the thermal expansion and contraction displacement between the inner and outer tubes. The displacement buffer is connected to the outer tube and is either a stuffing box double-sealed displacement buffer or a stuffing box double-sealed displacement buffer combined with a waveform expansion joint type displacement buffer. It features the ability to adapt to the needs of large-scale and high-capacity production, strong performance in absorbing thermal expansion and contraction displacement, good sealing performance, high strength, and simple assembly.

[0005] Traditional sealing principle

[0006] As shown above, the sealing principle of the stuffing box in a loop reactor is that the pressure plate of the packing gland applies a load to the packing, causing plastic and elastic deformation. During the compression process, axial compression is generated, and radial force is also produced, resulting in a tight seal with the outer wall of the inner tube and the inner wall of the outer tube. The compression force of the pressure plate is related to the pressure of the medium in the jacket between the inner and outer tubes, as well as other factors such as the permeability of the medium. The general consensus is that the required compression force should be directly proportional to the medium pressure. The packing length is generally proportional to the medium pressure; higher pressures require more packing rings.

[0007] Technical problems exist

[0008] In practical applications, excessive packing rings can lead to insufficient compression force, making it difficult for the packing to reach the deeper layers due to friction. The innermost rings of packing may not provide a proper seal due to insufficient compression, further increasing friction between the packing and the outer pipe and consequently increasing thermal stress on the outer pipe. Therefore, more packing is not necessarily better; it should be determined through calculation and experience.

[0009] The first problem is the insufficient attention paid to the dynamic nature of the sealing structure. Only the axial sliding of the outer tube seal was recognized, neglecting the radial changes in the sealing structure. The internal pressure of the medium, the radial pressure of the stuffing box, and thermally induced radial expansion all cause changes in the radial sealing diameter and clearance. In fact, the radial dynamics of the structure are the primary factor in sealing; axial dynamics must be converted into radial dynamics to affect the seal. Regardless of whether the two sealing surfaces are relatively stationary, sliding axially, or rotating circumferentially, in the axial and radial sealing functions of the stuffing box, the radial sealing function is often primary, and the axial sealing function is secondary. This differs from the axial and radial sealing functions of O-rings, where the axial sealing function is often primary and the radial sealing function secondary in end cap O-ring seals.

[0010] The second problem lies in the crude design of the outer tube's seal. Current technology for sealing between the inner and outer tubes makes it difficult to confirm the relationship between the temperature conditions of the stuffing box application and the structure and dimensions specified in the standards, and fails to analyze in detail the adverse effects of high-temperature structural deformation on the seal. Existing standards generally use a common amplification factor multiplied by the design pressure as a basic requirement, which does not easily take into account the difference between the radial sealing principle of the stuffing box and the axial sealing principle of the equipment flange studs.

[0011] For example, Chinese patent document CN102836683A discloses a self-tightening stuffing box sealing displacement buffer and a ring tube reactor. In addition to absorbing thermal expansion and contraction displacement, it also has a triple sealing function: first, the primary sealing of the rubber sealing ring; second, the dynamic sealing of the packing; and third, the self-tightening sealing of the inclined sealing body after the packing is squeezed, which enhances its dynamic sealing performance.

[0012] The existing technology mentioned above relies on a rubber sealing ring to block one end of the packing. The structure of the packing combined with the rubber sealing ring is complex. The rubber sealing ring has a certain degree of elasticity, which makes it inconvenient to install. In addition, the rubber sealing ring will deform, and the packing can easily squeeze into the gap between the rubber sealing ring and the outer wall of the inner tube. Summary of the Invention

[0013] In view of the above-mentioned technical problems in the prior art, the present invention provides a stuffing box nozzle with pre-tightening compensation and a heat exchanger with the same.

[0014] To achieve the above objectives, the present invention provides the following technical solution:

[0015] A stuffing box type fitting with pre-tightening compensation is provided, comprising an inner tube, an outer tube, and a sealing assembly. The inner tube is inserted into the outer tube. The sealing assembly slidably seals the outer tube to the outer wall of the inner tube. The sealing assembly includes a packing pressure ring, a sealing box, packing, and fasteners. The sealing box is connected to the end of the outer tube. A receiving annular cavity is provided between the inner side of the sealing box and the outer wall of the inner tube. The packing is located in the receiving annular cavity. The packing pressure ring and the sealing box cooperate with each other. One end of the packing pressure ring presses the end of the packing away from the outer tube, and the other end of the packing pressure ring is connected to the sealing box by fasteners. An inclined body is provided in the receiving annular cavity. The packing conforms to the inclined surface of the inclined body so that the inclined surface simultaneously squeezes the packing in the radial and axial directions when the inner tube is thermally expanded. The sealing box is characterized by having a metal retaining ring between the inner side of the sealing box and the outer wall of the inner tube. The retaining ring is tightly fitted to the outer wall of the inner tube and presses the end of the packing near the outer tube.

[0016] As a further optional solution, a limiting step is provided on the inner side of the sealing box, and a limiting groove is provided on the retaining ring. The limiting groove is embedded in the limiting step to limit the retaining ring in the direction of receiving the ring cavity; a mating conical surface is provided between the outer wall surface of the retaining ring and the sealing box.

[0017] As a further alternative, the retaining ring is welded to the outer wall of the inner tube.

[0018] As a further alternative, the retaining ring is fixed to the outer wall of the inner tube by bolts.

[0019] As a further alternative, the inclined body is located on the inner wall of the sealing box, and the inclined surface of the inclined body gradually rises along the thermal elongation direction of the inner tube.

[0020] As a further alternative, the inclined body is located on the outer wall of the inner tube, and the inclined surface of the inclined body gradually decreases along the thermal elongation direction of the inner tube.

[0021] As a further alternative, the retaining ring is provided with a support portion that extends to the end of the ring cavity that abuts against the packing.

[0022] A heat exchanger, which is a series-tube reactor, includes multiple straight and bent tubes. Each bent tube includes an outer bend and an inner bend, with the outer bend fitting over the inner bend to form an annular bent-jacket flow channel. Each straight tube includes an inner straight tube and an outer straight tube, with the inner straight tube passing through the outer straight tube. An annular straight-jacket flow channel is formed between the inner and outer straight tubes. The inner bend and the inner straight tube are connected in series to form a medium flow channel for transporting reactants and for reaction. The straight-jacket flow channel and the bent-jacket flow channel are connected in series to form a cooling flow channel for transporting cooling medium. The characteristic feature is that the straight tubes and / or bent tubes are pre-tightened and compensated stuffing box nozzles as described above.

[0023] A heat exchanger, which is a shell-and-tube heat exchanger, includes an upper tube box, a lower tube box, an upper tube sheet, a lower tube sheet, a shell, and multiple heat exchange tubes arranged in parallel. The upper tube sheet is fixed to the upper end of the shell, the upper tube box is fixed to the top of the upper tube sheet and is provided with an outlet pipe, the lower tube box includes a box body and an inlet pipe, and the inlet pipe is fixed to the box body; the upper end of the heat exchange tube is fixed to the upper tube sheet and communicates with the upper tube box; the lower tube sheet is located inside the shell and a gap is left between its periphery and the inner wall of the shell; a floating tube box and a floating connecting pipe are provided in the shell and the lower tube box, the upper end of the floating tube box is fixedly connected to the lower tube sheet, the lower end of the heat exchange tube is connected to the lower tube sheet and communicates with the floating tube box, the upper end of the floating connecting pipe is fixedly connected to and communicates with the floating tube box, the floating connecting pipe passes through the inlet pipe, and there is a movable space between the bottom of the floating tube box and the lower tube box. The floating connecting pipe and the inlet pipe are filled with a pre-tightened compensation stuffing box as described above, the floating connecting pipe is the inner tube, and the inlet pipe is the outer tube.

[0024] Specifically, the floating tube box and the lower tube sheet are connected by a detachable flange, and / or the lower tube box and the shell are connected by a detachable flange.

[0025] The beneficial effects of this invention are:

[0026] The pre-tightening compensated stuffing box nozzle and heat exchanger of the present invention, compared with the prior art, use a retaining ring to compress the packing, which is simple in structure and easy to assemble; moreover, the retaining ring is not easily deformed, and the packing is fully clamped by the retaining ring and the packing pressure ring. Combined with the inclined body in the ring cavity, the axial and radial sealing effect of the packing can be fully utilized during operation; furthermore, the retaining ring can fit tightly against the outer wall of the inner tube to prevent the packing from being squeezed into the gap between the retaining ring and the inner tube, thus ensuring the long-term sealing effect of the packing. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the stuffing gland nozzle with pre-tightening compensation in Example 1.

[0028] Figure 2 This is a schematic diagram of the stuffing gland nozzle with pre-tightening compensation in Example 2.

[0029] Figure 3 This is a schematic diagram of the packing gland nozzle with pre-tightening compensation in Example 3.

[0030] Figure 4 This is a schematic diagram of the stuffing gland nozzle with pre-tightening compensation in Example 4.

[0031] Figure 5 This is a schematic diagram of the packing gland nozzle with pre-tightening compensation in Example 5.

[0032] Figure 6This is a schematic diagram of the stuffing gland nozzle with pre-tightening compensation in Example 6.

[0033] Figure 7 This is a schematic diagram of the structure of the serial tube reactor in the embodiment.

[0034] Figure 8 This is a schematic diagram of the shell-and-tube heat exchanger in the embodiment.

[0035] Figure label:

[0036] Inner tube 1, outer tube 2;

[0037] Sealing assembly 3, packing ring 31, sealing box 32, receiving ring cavity 321, limiting step 322, packing 33, fastener 34, retaining ring 35, limiting groove 351, support part 352; inclined body 36;

[0038] Upper tube box 4, exhaust pipe 41, lower tube box 5, box body 51, inlet pipe 52, upper tube sheet 6, lower tube sheet 7, shell 8, heat exchange tube 9, floating tube box 10, floating pipe 11. Detailed Implementation

[0039] The present invention will be described in detail below with reference to specific embodiments and accompanying drawings.

[0040] One specific embodiment of the pre-tightening compensated stuffing box nozzle of the present invention is as follows: Figure 1 As shown, the device includes an inner tube 1, an outer tube 2, and a sealing assembly 3. The inner tube 1 is inserted into the outer tube 2. The sealing assembly 3 slidably seals the end of the outer tube 2 to the outer wall of the inner tube 1. The sealing assembly 3 includes a packing ring 31, a sealing gland 32, packing 33, and fasteners 34. The sealing gland 32 is welded and fixed to the end of the outer tube 2. A receiving annular cavity 321 is provided between the inner side of the sealing gland 32 and the outer wall of the inner tube 1. The packing 33 is filled in the receiving annular cavity 321. The L-shaped packing ring 31 and the sealing gland 32 cooperate with each other. One end of the packing ring 31 presses the end of the packing 33 away from the outer tube 2. The other end of the packing ring 31 is connected to the sealing gland 32 through the fasteners 34. The fasteners 34 are bolt and nut assemblies. The degree of pressing of the packing 33 is adjusted by tightening the nuts.

[0041] In this embodiment, a rigid metal retaining ring 35 is provided between the inner side of the sealing box 32 and the outer wall of the inner tube 1. The retaining ring 35 fits tightly against the outer wall of the inner tube 1, and presses the end of the packing 33 near the outer tube 2. In this way, the retaining ring 35 and the packing pressure ring 31 together clamp and limit the packing 33. The rigid metal retaining ring 35 is not easily deformed, and has a good limiting and compressing effect on the packing 33.

[0042] In this embodiment, a limiting step 322 is provided on the inner side of the sealing box 32, and a limiting groove 351 is provided on the retaining ring 35. The limiting groove 351 is embedded in the limiting step 322 to limit the retaining ring 35 towards the receiving annular cavity 321. This method eliminates the need for welding and bolt holes on the outer surface of the inner tube 1, preventing damage and making it the optimal embodiment. In practice, a small-angle mating conical surface can be provided between the outer wall of the retaining ring 35 and the sealing box 32 to ensure that the inner wall of the retaining ring 35 always adheres tightly to the outer surface of the inner tube 1, preventing the packing from squeezing into the gap. Specifically, the retaining ring 35 is provided with a support portion 352, which extends into the receiving annular cavity 321 and abuts against the end of the packing 33, improving the limiting effect on the packing 33. A radial space is left between the support 352 and the inner wall of the sealing box 52, so that the packing 33 is partially squeezed into the radial space. During operation, the packing 33 inside squeezes the support 321 towards the inner tube 1, so that the pressure ring 55 is more closely attached to the outer wall of the inner tube 1.

[0043] In this embodiment, an inclined body 3 with a right-angled triangular cross-section is provided in the receiving ring cavity 321. The long right-angle side of the inclined body 3 is attached to the inner wall surface of the sealing box 32, and the packing ring 31 abuts against the short right-angle side of the inclined body 3. Along the thermal elongation direction of the inner tube 1, the inclined surface of the inclined body 3 gradually rises, and the packing 33 is attached to the inclined surface of the inclined body 3. During use, the inner tube 1 is heated and elongated, and the retaining ring 35 and the packing 33 are driven by friction. Figure 1 As the packing 33 slides from left to right, it is simultaneously compressed and deformed radially and axially as it climbs the inclined surface of the inclined body 3. The diameter of the packing 33 is reduced due to space constraints, thus improving the sealing effect both radially and axially. Even if the packing 33 is not fully compressed and is in a pre-tightened state during assembly, it still provides pre-tightening compensation during operation.

[0044] Example 2

[0045] A second specific embodiment of the pre-tightening compensated stuffing box nozzle of the present invention, as follows: Figure 2 As shown, the main technical solution of this embodiment is the same as that of Embodiment 1. Features not explained in this embodiment are explained using the methods in Embodiment 1, and will not be repeated here. The difference between this embodiment and Embodiment 1 is that the retaining ring 35 is welded and fixed to the outer wall surface of the inner tube 1. Welding is a secondary preferred solution.

[0046] Example 3

[0047] The third specific embodiment of the pre-tightening compensated stuffing box nozzle of the present invention is as follows: Figure 3As shown, the main technical solution of this embodiment is the same as that of Embodiment 1. Features not explained in this embodiment are explained using the methods in Embodiment 1, and will not be repeated here. The difference between this embodiment and Embodiment 1 is that the retaining ring 35 is fixed to the outer wall of the inner tube 1 by bolts. Bolt holes need to be opened on the outer surface of the inner tube 1, which will obviously be damaged, but loosening the bolts makes it easy to disassemble the parts. Therefore, this embodiment is the third option.

[0048] Example 4

[0049] The fourth specific embodiment of the pre-tightening compensated stuffing box nozzle of the present invention is as follows: Figure 4 As shown, the main technical solution of this embodiment is the same as that of Embodiment 1. Features not explained in this embodiment are explained using the methods in Embodiment 1, and will not be repeated here. The difference between this embodiment and Embodiment 1 is that the inclined body 3 is located on the outer wall surface of the inner tube 1, and the inclined surface of the inclined body 3 gradually decreases along the thermal elongation direction of the inner tube 1. Although the packing 33 slides in the direction of larger space, the space accommodating the annular cavity 321 is compressed, and the packing 33 can still improve the sealing effect to a certain extent in both the axial and radial directions.

[0050] Example 5

[0051] The fifth specific embodiment of the pre-tightening compensated stuffing box nozzle of the present invention, as follows: Figure 5 As shown, the main technical solution of this embodiment is the same as that of embodiment 4. Features not explained in this embodiment are explained in embodiment 4 and will not be repeated here. The difference between this embodiment and embodiment 4 is that the retaining ring 35 is welded and fixed to the outer wall surface of the inner tube 1.

[0052] Example 6

[0053] The sixth specific embodiment of the pre-tightening compensated stuffing box nozzle of the present invention, as follows: Figure 6 As shown, the main technical solution of this embodiment is the same as that of embodiment 4. Features not explained in this embodiment are explained in embodiment 4 and will not be repeated here. The difference between this embodiment and embodiment 4 is that the retaining ring 35 is fixed to the outer wall of the inner tube 1 by bolts.

[0054] The present invention also provides a heat exchanger with a pre-tightened compensation packing gland nozzle according to any of embodiments 1 to 6, wherein one application combines... Figure 7 As shown, the heat exchanger is a series-tube reactor. Figure 7This diagram illustrates a prior art series-tube reactor, which will be used to illustrate this example. It includes multiple straight sleeves R1-R6 and bent sleeves A1, A2, and A3. Each bent sleeve includes an outer bend and an inner bend, with the outer bend fitting over the inner bend to form an annular bent-jacket flow channel. Each straight sleeve includes an inner straight pipe and an outer straight pipe, with the inner straight pipe passing through the outer straight pipe, forming an annular straight-jacket flow channel between them. The inner bend and the inner straight pipe are connected in series to form a medium flow channel for transporting reactants and for the reaction process. The straight-jacket flow channel and the bent-jacket flow channel are connected in series via a connecting pipe through the side wall of the outer pipe 2 to form a cooling flow channel for transporting cooling medium. 1B and 1A are the inlet and outlet of the cooling flow channel and the medium flow channel, respectively. In a specific application, the straight sleeve is a pre-tightened compensation stuffing box type connecting pipe as described in any of the above embodiments, with the inner pipe serving as the inner pipe 1 and the outer straight pipe serving as the outer pipe 2. Similarly, the elbow can also be a pre-tightening compensation stuffing box pipe as described in any of the above embodiments, with the inner elbow as the inner pipe 1 and the outer elbow as the outer pipe 2.

[0055] The second type of heat exchanger with a pre-tightened compensated stuffing box nozzle in any of the application embodiments 1 to 6 of the present invention, such as Figure 8 As shown, it is a shell-and-tube heat exchanger, including an upper tube box 4, a lower tube box 5, an upper tube sheet 6, a lower tube sheet 7, a shell 8, and multiple heat exchange tubes 9 arranged in parallel. The upper tube sheet 6 is fixed to the upper end of the shell 8. The upper tube box 4 is fixed to the top of the upper tube sheet 6 and is provided with an exhaust pipe 41. The lower tube box 5 includes a housing 51 and an inlet pipe 52, with the inlet pipe 52 fixed to the housing 51. The upper ends of the heat exchange tubes 9 are welded and fixed to the upper tube sheet 6 and connected to the upper tube box 4. The lower tube sheet 7 is located in the shell. A gap is left between the interior and periphery of the body 8 and the inner wall of the shell 8; a floating tube box 10 and a floating pipe 11 are provided inside the shell 8 and the lower tube box 5. The upper end of the floating tube box 10 is fixedly connected to the lower tube sheet 7, the lower end of the heat exchange tube 9 is connected to the lower tube sheet 7 and communicates with the floating tube box 10, the upper end of the floating pipe 11 is fixedly connected to and communicates with the floating tube box 10, and the floating pipe 11 passes through the air inlet pipe 52. There is a movable space between the floating tube box 10 and the bottom of the lower tube box 5. In a specific application, the floating pipe 11 and the air inlet pipe 52 are stuffing gland type pipes with pre-tightening compensation of any of the above embodiments, the floating pipe 11 serves as the inner pipe 1, and the air inlet pipe 52 serves as the outer pipe 2.

[0056] Specifically, the floating tube box 10 and the lower tube sheet 7 are connected by a detachable flange, and / or the lower tube box 5 and the shell 8 are connected by a detachable flange, which facilitates manufacturing, installation and maintenance.

[0057] In the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0058] All standard parts used in this invention can be purchased from the market, and irregular parts can be customized according to the description and drawings. The specific connection methods of each part adopt conventional methods such as bolts, rivets, and welding that are mature in the prior art. The machinery, parts and equipment adopt conventional models in the prior art, and the circuit connection adopts conventional connection methods in the prior art, which will not be described in detail here.

[0059] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A stuffing box type fitting with pre-tightening compensation, comprising an inner tube, an outer tube, and a sealing assembly, wherein the inner tube is inserted into the outer tube, and the sealing assembly slidably seals the outer tube to the outer wall of the inner tube. The sealing assembly includes a packing pressure ring, a sealing box, packing, and fasteners. The sealing box is connected to the end of the outer tube, and a receiving annular cavity is provided between the inner side of the sealing box and the outer wall surface of the inner tube. The packing is located in the receiving annular cavity. The packing pressure ring and the sealing box cooperate with each other. One end of the packing pressure ring presses the end of the packing away from the outer tube, and the other end of the packing pressure ring is connected to the sealing box by fasteners. An inclined body is provided in the receiving annular cavity, and the packing conforms to the inclined surface of the inclined body so that the inclined surface simultaneously compresses the packing in the radial and axial directions when the inner tube is thermally expanded. The fitting is characterized in that: A metal retaining ring is provided between the inner side of the sealing box and the outer wall of the inner tube. The retaining ring fits tightly against the outer wall of the inner tube and presses the end of the packing near the outer tube. The retaining ring is provided with a support part that extends into the receiving ring cavity and abuts against the end of the packing. A radial space is left between the support part and the inner wall of the sealing box, so that part of the packing is squeezed into the radial space. During operation, the packing inside is squeezed towards the support part towards the inner tube, making the retaining ring fit more tightly against the outer wall of the inner tube.

2. The stuffing box fitting with pre-tightening compensation according to claim 1, characterized in that: The inner side of the sealing box is provided with a limiting step, and the retaining ring is provided with a limiting groove. The limiting groove is embedded in the limiting step to limit the retaining ring in the direction of receiving the ring cavity; a mating conical surface is provided between the outer wall surface of the retaining ring and the sealing box.

3. The stuffing box fitting with pre-tightening compensation according to claim 1, characterized in that: The retaining ring is welded and fixed to the outer wall of the inner tube.

4. The stuffing box fitting with pre-tightening compensation according to claim 1, characterized in that: The retaining ring is fixed to the outer wall of the inner tube by bolts.

5. The stuffing box fitting with pre-tightening compensation according to claim 2, 3, or 4, characterized in that: The inclined body is located on the inner wall of the sealing box, and the inclined surface of the inclined body gradually rises along the thermal elongation direction of the inner tube.

6. The stuffing box fitting with pre-tightening compensation according to claim 2, 3, or 4, characterized in that: The inclined body is located on the outer wall of the inner tube, and the inclined surface of the inclined body gradually decreases along the thermal elongation direction of the inner tube.

7. A heat exchanger, which is a series-tube reactor, includes multiple straight and bent tubes. Each bent tube includes an outer bend and an inner bend, with the outer bend fitting over the inner bend to form an annular bent-jacket flow channel. Each straight tube includes an inner straight tube and an outer straight tube, with the inner straight tube passing through the outer straight tube. The inner and outer straight tubes form an annular straight-jacket flow channel. The inner bend and the inner straight tube are connected in series to form a medium flow channel for transporting reactants and for reaction. The straight-jacket flow channel and the bent-jacket flow channel are connected in series to form a cooling flow channel for transporting cooling medium. Its characteristic is: The straight sleeve and / or bent sleeve are the stuffing gland fittings with pre-tightening compensation as described in any one of claims 1 to 6.

8. A heat exchanger, which is a shell-and-tube heat exchanger, includes an upper tube box, a lower tube box, an upper tube sheet, a lower tube sheet, a shell, and multiple heat exchange tubes arranged in parallel. The upper tube sheet is fixed to the upper end of the shell, the upper tube box is fixed to the top of the upper tube sheet and is provided with an outlet pipe, the lower tube box includes a box body and an inlet pipe, the inlet pipe is fixed to the box body; the upper end of the heat exchange tube is fixed to the upper tube sheet and communicates with the upper tube box; the lower tube sheet is located inside the shell and a gap is left between its periphery and the inner wall of the shell; a floating tube box and a floating connecting pipe are provided in the shell and the lower tube box, the upper end of the floating tube box is fixedly connected to the lower tube sheet, the lower end of the heat exchange tube is connected to the lower tube sheet and communicates with the floating tube box, the upper end of the floating connecting pipe is fixedly connected to and communicates with the floating tube box, the floating connecting pipe passes through the inlet pipe, and there is a movable space between the bottom of the floating tube box and the lower tube box. Its characteristic is: The floating connector and the intake pipe are both filled with a pre-tightened, compensated stuffing box connector as described in any one of claims 1 to 6, with the floating connector serving as the inner pipe and the intake pipe serving as the outer pipe.

9. The heat exchanger according to claim 8, characterized in that: The floating tube box and the lower tube sheet are connected by a detachable flange, and / or the lower tube box and the shell are connected by a detachable flange.

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