Tube pass inlet self-flowing high-efficiency spiral tube heat exchanger and working method thereof

Abstract

This invention discloses a tube-side inlet self-equalizing wound-tube heat exchanger and its operating method, belonging to the technical field of heat exchange equipment. In this invention, the wound-tube heat exchanger consists of multiple heat exchange tubes wound around the outside of a central cylinder, with the outer heat exchange tubes having a longer length than the inner heat exchange tubes. A tube-side distribution mechanism is provided at the tube-side inlet, including a swirling guide shroud. Multiple swirling plates are uniformly arranged circumferentially inside the shroud, evenly dividing the cavity into multiple spiral channels. The swirling plates are arranged at a helical angle relative to the axial centerline, guiding the medium to generate swirling motion. This ensures that the linear velocity of the medium at the inlet of the outer heat exchange tubes is greater than that at the inlet of the inner heat exchange tubes, compensating for the additional friction loss caused by the increased tube length of the outer heat exchange tubes, and achieving active and balanced flow distribution among the heat exchange tube layers. This invention solves the flow deviation problem of wound-tube heat exchangers from the tube-side inlet source, significantly improving heat transfer efficiency and operational reliability.

Description

Technical Field

[0001] This invention belongs to the technical field of heat exchange equipment, specifically relating to a wound tube heat exchanger, and more particularly to a high-efficiency wound tube heat exchanger and its working method that achieves active control of flow velocity gradient through the coordinated action of the tube-side inlet buffer cavity and the swirl guide shroud. It can be widely used in heat transfer and energy optimization processes in fields such as petrochemicals, natural gas liquefaction, and marine engineering. Background Technology

[0002] Tube-wound heat exchangers (also known as wound tube heat exchangers) are widely used in large-scale industrial processes such as natural gas liquefaction, cryogenic separation in petrochemicals, and air separation due to their compact structure, large heat transfer area, and ability to handle multiple fluids simultaneously. Their basic structure consists of a central cylinder within a shell, with multiple heat exchange tubes spirally wound layer by layer around the outside of the central cylinder, forming a multi-layered tube bundle. The tube-side medium enters each heat exchange tube through the tube-side inlet, while the shell-side medium enters the shell through the shell-side inlet and exchanges heat with the tube-side medium through a wall-to-wall heat exchange. However, with the increasing scale of industrial plants and the ever-increasing demands for heat exchange efficiency and operational reliability, traditional tube-wound heat exchangers have revealed several technical problems that urgently need to be addressed in practical engineering applications.

[0003] Regarding the tube-side fluid distribution, the tube bundle is spirally wound around the central cylinder, with significant differences in tube length between each layer—the length of a single tube in the outer ring is much greater than that in the inner ring. In traditional tube-side inlet structures, the tube-side medium enters the tube sheet cavity directly through the inlet tube. Due to the different friction resistances of each layer of heat exchange tubes, the flow distribution between branches is severely uneven, with some tubes having excessively low flow velocities and others having excessively high flow velocities, resulting in flow deviation. This flow deviation not only leads to uneven heat transfer load distribution among the heat exchange tubes and a decrease in overall heat transfer efficiency, but also causes problems such as medium stagnation and scaling due to abnormal local flow velocities, making it difficult to guarantee the reliability of the equipment under long-term operation.

[0004] Regarding shell-side fluid distribution, traditional shell-side inlets often employ a radial straight-through nozzle structure. After the shell-side medium enters the shell through the inlet pipe, a flow dead zone is formed in the area directly opposite the nozzle due to the interaction between the fluid inertia and the inner wall of the shell. The sluggish flow within this dead zone easily leads to the deposition and accumulation of solid particles, corrosion products, and process impurities carried in the shell-side medium, thereby inducing under-deposit corrosion and localized pitting corrosion, seriously threatening the long-term safe operation of the equipment. Furthermore, the helical arrangement of the tube bundles themselves exacerbates the complexity of the shell-side flow, easily forming flow dead zones in the annular space between the tube bundle and the inner wall of the shell, preventing the effective utilization of a large amount of heat exchange area.

[0005] In terms of heat transfer enhancement, traditional wound-tube heat exchangers mostly use smooth tubes, limiting the potential for improving the heat transfer coefficient both inside and outside the tubes. Although there have been technical attempts in this field to use enhanced heat transfer tubes such as internally threaded tubes and spiral finned tubes in heat exchangers, the potential of the enhanced heat transfer structure cannot be fully realized under the premise of uneven fluid distribution. When the flow rate in some pipelines deviates from the design value, even if the tube itself has an enhanced heat transfer structure, its heat transfer capacity is limited due to the abnormal medium flow rate.

[0006] To address the aforementioned issues, some improvements have been proposed in the prior art. For example, CN106767109A discloses a shell-side fluid distribution and guiding device, which improves the shell-side fluid distribution by setting an annular baffle and a spiral guide plate inside the shell; CN205482474U discloses a coiled tube heat exchanger with a medium distributor, which achieves shell-side medium distribution through an annular channel and a distribution hole; CN102865755A sets spiral guide rings at the inlet of the shell and tube sides to form a spiral flow channel. However, the above-mentioned prior art still has the following shortcomings: First, existing solutions mostly focus on improving the shell-side fluid distribution, and lack effective solutions for the flow deviation problem caused by the inherent tube length difference in the coiled tube structure in the tube side; Second, the existing tube side inlet guiding structure is of a single type, which is difficult to adapt to the differentiated flow characteristics of each layer of the coiled tube heat exchanger; Third, the existing technology does not systematically integrate the optimization of tube side fluid distribution with the improvement of shell side structure, and the overall improvement of heat transfer performance still faces bottlenecks.

[0007] Therefore, developing a tube-wound heat exchanger that can improve the uniformity of fluid distribution from the tube inlet while eliminating the shell dead zone and enhancing heat transfer inside and outside the tube has become a technical issue that urgently needs to be addressed by those skilled in the art. Summary of the Invention

[0008] (a) The technical problem to be solved by the present invention This invention primarily addresses the flow deviation problem in existing wound-tube heat exchangers caused by differences in tube length between different layers of heat exchange tubes. It provides a self-equalizing flow wound-tube heat exchanger with a tube-side inlet and its operating method. This invention utilizes a swirling flow guide shroud at the tube-side inlet, employing swirling plates to guide the medium and generate swirling motion. This ensures that the linear velocity of the medium at the inlet of the outer heat exchange tubes is greater than that at the inlet of the inner heat exchange tubes, compensating for the additional friction loss caused by the increased tube length of the outer heat exchange tubes. This achieves active and balanced flow distribution among the heat exchange tubes, solving the technical problem of flow deviation in existing wound-tube heat exchangers. Simultaneously, this invention eliminates dead zones in the shell-side flow through a shell-side distribution mechanism, and combined with enhanced heat transfer structures inside and outside the heat exchange tubes, synergistically improves the overall heat transfer efficiency and operational reliability of the wound-tube heat exchanger from both the tube-side and shell-side perspectives.

[0009] (II) Detailed description of the technical solution of the present invention To achieve the above objectives, the present invention adopts the following technical solution: 1. Basic structure of a wound tube heat exchanger This invention provides a tube-side inlet self-equalizing wound tube heat exchanger, comprising a shell, a tube sheet, a wound tube bundle, and a central cylinder. The shell is a cylindrical structure with end caps at both ends, each end cap having a tube-side inlet and a tube-side outlet. A shell-side inlet and a shell-side outlet are also provided on the side of the shell. The tube sheet is fixedly installed at both ends within the shell, and the central cylinder is positioned axially at the center of the shell. The wound tube bundle consists of multiple heat exchange tubes wound around the outside of the central cylinder. The heat exchange tubes are arranged in layers radially from the inside to the outside of the central cylinder, with the outermost heat exchange tubes having a longer tube length than the innermost heat exchange tubes.

[0010] 2. Pipeline distribution mechanism This invention includes a tube-side distribution mechanism at the tube-side inlet for regulating and distributing the flow rate of the medium entering the tube-side. The tube-side distribution mechanism includes a swirling guide shroud, which is disposed in the tube-side fluid channel between the tube-side inlet and the tube sheet.

[0011] The swirling flow guide shroud has an overall cylindrical structure, with N swirling plates evenly arranged circumferentially inside, where N ≥ 4. Preferably, N = 6, with six swirling plates evenly distributed circumferentially, dividing the cavity of the swirling flow guide shroud into six 60° spiral channels. Each swirling plate is arranged at a helical angle relative to the axial centerline of the swirling flow guide shroud, meaning that each swirling plate extends axially while twisting at a certain angle circumferentially.

[0012] Its working principle is as follows: After the tube-side medium enters the vortex guide shroud from the tube-side inlet, it is forced to flow along the spiral channel under the guidance of the vortex plate, thereby generating vortex motion. Due to the velocity distribution characteristics of the vortex motion—the peripheral linear velocity is higher than the central linear velocity—a circumferential velocity gradient distribution is formed at the outlet of the vortex guide shroud: the linear velocity of the medium is higher on the side near the inner wall of the shell (corresponding to the outer heat exchange tube of the tube bundle), and lower on the side near the central cylinder (corresponding to the inner heat exchange tube of the tube bundle).

[0013] The intensity of the swirling flow can be controlled by appropriately setting the helix angle of the swirling plate. A greater swirling intensity results in a greater difference in linear velocity between the outer and inner layers, allowing for the matching of appropriate friction loss compensation requirements based on parameters such as the number of layers and the tube length ratio of the tube bundle. The medium at the inlet of the outer heat exchange tubes achieves higher local dynamic pressure due to its higher inlet linear velocity, compensating for the additional friction loss caused by the increased tube length. This makes the total pressure drop at the inlet of each heat exchange tube layer more uniform, ultimately achieving a balanced distribution of the medium flow rate within each heat exchange tube layer.

[0014] 3. Buffer cavity (preferred structure) As a preferred embodiment, the tube-side distribution mechanism further includes a buffer chamber. The buffer chamber is located between the outlet of the tube-side distribution mechanism and the inlet of the coiled tube bundle. The buffer chamber is an annular gap cavity between the tube sheet and the swirl guide shroud, used to further buffer and mix the medium distributed by the swirl guide shroud.

[0015] Its function is as follows: Before entering each heat exchanger tube, the swirling medium, accelerated by the swirling guide shroud, undergoes a buffering space within the buffer chamber. This allows the high-velocity gradient swirling flow field to develop and transition smoothly, preventing direct impact of the high-speed swirling flow on the tube sheet and thus avoiding erosion. Simultaneously, the annular cavity structure of the buffer chamber has a certain volume, allowing for fine-tuning of circumferential local flow deviations. This makes the flow field at the inlet of each heat exchanger tube more uniform and stable, and ensures that the velocity gradient distribution formed by the swirling motion does not disappear due to buffering. The buffer chamber and the swirling guide shroud together constitute a complete tube-side flow velocity control path—the swirling guide shroud solves the problem of "how to generate swirling flow and velocity gradients," while the buffer chamber solves the problem of "how to smoothly transfer the swirling flow field to the inlet of each heat exchanger tube."

[0016] 4. Conical flow guide core (preferred structure) As a preferred embodiment, the swirl guide shroud also includes a conical guide core. The conical guide core is positioned at the center of the swirl guide shroud, is streamlined and conical in shape, with its tip pointing towards the tube inlet. Since the central cylinder surrounding the tube bundle is a solid structure and there are no openings in the center of the tube sheet, the conical guide core shields the ineffective flow area in the center corresponding to the central cylinder, guiding the medium to be evenly distributed in the circumferential spiral channels. This prevents the formation of dead zones or ineffective flow in the central region, thereby improving overall flow efficiency.

[0017] 5. Enhanced heat transfer heat exchanger tubes As a preferred embodiment, this invention employs a reinforced heat transfer tube as the heat exchange tube in the tube bundle. The heat exchange tube is a reinforced heat transfer tube with spiral microribs on its inner wall. The height of the spiral microribs is 0.2~0.5mm, and the pitch is 3~8mm. The spiral microribs are formed through precision rolling and electrochemical polishing processes, used to disrupt the boundary layer inside the tube, thereby increasing the heat transfer coefficient inside the tube by 40%~60%.

[0018] Meanwhile, the outer wall of the heat exchange tube is wound with spiral fins, the fin height of which is 3-6 mm and the fin spacing is 5-10 mm. The spiral fins are fixed to the outer wall of the heat exchange tube by high-frequency welding and stress relief process, which is used to expand the heat transfer area outside the tube by 3-5 times and increase the heat transfer coefficient outside the tube by 3-4 times.

[0019] The spiral microribs inside the tube and the spiral fins outside the tube work together to simultaneously enhance heat transfer from both the inside and outside of the tube. Under the premise that the flow rate of each heat exchange tube is evenly distributed in the tube-pass distribution mechanism, the medium flow velocity in each heat exchange tube is within a reasonable range, so that the enhanced heat transfer effect of the spiral microribs and spiral fins can be fully utilized, and the overall heat transfer efficiency is improved by 30% to 50%.

[0020] 6. Shell side distribution mechanism As a preferred embodiment, a shell-side distribution mechanism is provided at the shell-side inlet to eliminate shell-side flow dead zones. The shell-side distribution mechanism includes an internally extending annular inlet pipe and multiple rows of jet holes disposed on the wall of the internally extending annular inlet pipe.

[0021] The extended annular inlet pipe extends radially into the shell from the side wall, extending the shell-side medium inlet into the shell and avoiding the flow field dead zone formed in the area directly opposite the inlet of a traditional non-extended pipe. The multiple rows of jet holes are evenly distributed along the axial and circumferential directions of the extended annular inlet pipe, allowing the shell-side medium to jet into the shell-side space in multiple directions around the pipe wall.

[0022] Preferably, the multi-row jet orifice comprises three rows of jet orifices arranged axially along the inner-extended annular inlet pipe. The jet directions of the three rows of jet orifices are respectively upward, approximately 60° upward, and approximately 30° upward. The upward jet impacts the top region of the inner wall of the shell, the 60° upward jet covers the annular space from the top to the middle, and the 30° upward jet mainly covers the middle and lower tube bundle regions. The three rows of jet orifices simultaneously jet from three different directions, achieving omnidirectional coverage of the shell-side space and ensuring uniform distribution of the shell-side medium upon entry into the shell.

[0023] In addition, an annular uniform distribution structure is provided at the shell-side outlet to eliminate the flow dead zone on the shell-side outlet side. The combination of the inward-extending multi-directional jet distribution at the inlet end and the annular uniform distribution structure at the outlet end ensures that the shell-side medium maintains a uniform distribution throughout its flow through the tube bundle, effectively eliminating the shell-side dead zone.

[0024] Preferably, the internally extended annular inlet pipe is evenly divided into multiple non-interconnected annular inlet pipe sections along the axial direction, and the shell-side inlet is correspondingly divided into the same number of non-interconnected shell-side inlet branches. Each shell-side inlet branch is connected to its corresponding annular inlet pipe section via an independent connecting pipe. This structure allows the shell-side medium to be circumferentially divided into multiple streams before entering the shell, effectively avoiding uneven circumferential distribution of the shell-side fluid caused by single-point feeding. Combined with the multi-directional jetting effect of the jet orifice, it further improves the circumferential uniformity of the shell-side fluid.

[0025] 7. Working Methods The present invention also provides a method for operating a tube-side inlet self-equalizing wound tube heat exchanger, comprising the following steps: S1: Tube-side medium inlet entry and swirl generation. The tube-side medium enters the tube-side distribution mechanism from the tube-side inlet and is guided by each spiral channel to generate swirl motion as it flows through the swirl guide shroud.

[0026] S2: Formation of a circumferential velocity gradient distribution. The swirling motion creates a circumferential velocity gradient distribution of the medium at the outlet of the tube-side distribution mechanism, with the linear velocity of the medium in the inlet region of the outer heat exchange tube being greater than that in the inlet region of the inner heat exchange tube. The swirling intensity is controlled by adjusting the helix angle of the swirling plate to match the friction loss compensation requirements under different numbers of tube layers and different tube length ratios.

[0027] S3: Flow rate equalization. Tube-side media with different linear velocity distributions enter their respective heat exchange tube layers. The media in the outer heat exchange tubes compensate for the additional friction loss caused by the increased tube length due to the higher inlet linear velocity, making the flow rate of the media in each heat exchange tube layer tend to be consistent.

[0028] S4: Heat exchange and outflow. After the tube-side medium exchanges heat with the shell-side medium through each heat exchange tube layer, it flows out through the tube outlet.

[0029] When the tube-side distribution mechanism further includes a buffer cavity disposed between its outlet and the inlet of the tube bundle, the tube-side medium, after being distributed by the swirling flow guide shroud, first enters the buffer cavity, where it is buffered and mixed again while maintaining the velocity gradient distribution formed by the swirling motion, and then enters each layer of heat exchange tubes.

[0030] (III) Beneficial Technical Effects Compared with the prior art, the present invention has the following beneficial technical effects: 1. Active flow balancing in the tube to eliminate flow deviation. This invention utilizes a swirling flow guide shroud with a swirl plate at the tube inlet. By leveraging the inherent velocity distribution characteristics of swirling motion—the outer linear velocity being higher than the center linear velocity—the linear velocity of the medium at the inlet of the outer heat exchange tubes is increased compared to that at the inlet of the inner heat exchange tubes. This proactively compensates for friction loss caused by differences in tube length at the tube inlet. Compared to traditional wound-tube heat exchangers with tube-side distribution deviations >15%, this invention can control the flow distribution deviation between heat exchange tube layers to ≤5%, fundamentally eliminating flow deviation.

[0031] Meanwhile, the swirl plate evenly divides the flow guide cavity into N circumferential spiral channels, so that the inlet fluid can achieve circumferential diversion and uniform distribution while generating swirl, further ensuring the consistency of flow between channels.

[0032] 2. Significantly improved heat transfer efficiency By evenly distributing the flow rate through the tubes, the medium velocity in each heat exchange tube layer is within a reasonable range. Combined with the dual-enhanced heat transfer structure of spiral microribs on the inner wall of the heat exchange tube (increasing the heat transfer coefficient inside the tube by 40%~60%) and spiral fins on the outer wall (increasing the heat transfer area outside the tube by 3~5 times and increasing the heat transfer coefficient by 3~4 times), the overall heat transfer efficiency is increased by 30%~50% compared to traditional wound tube heat exchangers. This can reduce the heat exchange area requirement by 30%~50%, directly reducing equipment manufacturing costs and floor space.

[0033] 3. Effective elimination of shell-side dead zones The internally extended annular inlet pipe structure at the shell-side inlet, combined with three rows of jet holes in different directions, ensures uniform distribution of the shell-side medium from the moment it enters the shell, effectively eliminating the dead zone in the flow field directly opposite the inlet pipe in traditional non-internally extended inlet types. The shell-side dead zone ratio is reduced from >20% in traditional coiled tube heat exchangers to ≤5%, significantly reducing the risk of corrosion due to medium retention and extending the equipment's service life.

[0034] 4. Operational reliability has been greatly improved. Eliminating tube-side flow deviation avoids problems such as medium retention, scaling, and thermal decomposition caused by excessively low local flow velocities; eliminating shell-side dead zones prevents the deposition and accumulation of solid particles and corrosion products, effectively inhibiting under-deposit corrosion and localized pitting corrosion. These dual improvements significantly enhance the long-term operational reliability of the coiled-tube heat exchanger.

[0035] 5. Strong process adaptability By adjusting the helix angle of the swirl plate in the swirl guide, the swirl intensity can be flexibly controlled, thereby matching the friction resistance compensation requirements under various working conditions such as different number of tube layers, different tube length ratios, and different media properties, and has wide industrial application adaptability. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the overall structure of the tube-side inlet self-equalizing wound tube heat exchanger of the present invention; Figure 2 This is a schematic diagram of the circumferential arrangement of the swirl plates inside the swirl guide shroud of the present invention; Figure 3 This is a schematic diagram of the tube sheet at the tube inlet of the present invention; Figure 4 This is a schematic diagram of the shell-side distribution mechanism of the present invention; Figure 5 This is a cross-sectional view of the jet hole in the present invention; Figure 6 This is a schematic diagram showing the positions of the spiral microribs and spiral fins of the present invention; Figure 7 This is a schematic diagram of the shell-side inlet branch of the present invention.

[0037] The meanings of the markings in the diagram are as follows: 1—Shell; 2—Tube sheet; 3—Wound tube bundle; 31—Heat exchange tube; 311—Helical microrib; 312—Helical fin; 4—Central cylinder; 5—Tube-side inlet; 6—Tube-side outlet; 7—Shell-side inlet; 701—Shell-side inlet branch; 8—Shell-side outlet; 9—Tube-side distribution mechanism; 91—Swirl guide shroud; 911—Swirl plate; 912—Helical channel; 92—Buffer chamber; 93—Conical guide core; 10—Shell-side distribution mechanism; 101—Internal extended annular inlet tube; 101a—Annular inlet tube section; 102—Jet orifice; 103—First row of jet orifices (upward direction); 104—Second row of jet orifices (slanted upward at 60°); 105—Third row of jet orifices (slanted upward at 30°); 11—Outlet annular uniform distribution structure. Detailed Implementation

[0038] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0039] Example 1 like Figures 1-6 As shown, this embodiment provides a tube-side inlet self-equalizing wound tube heat exchanger, including a shell 1, a tube sheet 2, a wound tube bundle 3, and a central cylinder 4. The shell 1 is a cylindrical structure, made of Q345R low carbon steel or stainless steel. Both ends of the shell 1 are end caps, with tube-side inlets 5 and tube-side outlets 6 respectively. The sides of the shell 1 have shell-side inlets 7 and shell-side outlets 8. The tube sheet 2 is fixedly installed at both ends within the shell 1. The tube sheet 2 has tube holes corresponding to the number of heat exchange tubes 31 in the wound tube bundle 3, for installing the ends of each heat exchange tube 31. The central cylinder 4 is located at the center of the shell 1 along its axial direction, and both ends of the central cylinder 4 are fixedly connected to the tube sheet 2.

[0040] The tube bundle 3 consists of multiple heat exchange tubes 31 wound around the outside of the central cylinder 4. The heat exchange tubes 31 are arranged in layers from the inside to the outside along the radial direction of the central cylinder 4, with spacers (not shown in the figure) maintaining the distance between adjacent layers. In this embodiment, the tube bundle 3 has a total of 5 layers. The innermost heat exchange tube has a length of L, and the outermost heat exchange tube has a length of approximately 2L. The outer heat exchange tube is significantly longer than the inner heat exchange tube, resulting in a much greater frictional resistance in the outer layer compared to the inner layer.

[0041] like Figure 1 and Figure 2 As shown, a tube distribution mechanism 9 is provided at the tube inlet 5. The tube distribution mechanism 9 includes a swirl guide shroud 91 and a buffer chamber 92.

[0042] A vortex guide shroud 91 is disposed in the tube-side fluid channel between the tube-side inlet 5 and the tube sheet 2. It has an overall conical structure and is arranged along the axial direction of the shell 1. The inlet end of the vortex guide shroud 91 is connected to the pipe of the tube-side inlet 5, and the outlet end is connected to the buffer chamber 92. The vortex guide shroud 91 is made of stainless steel plate of the same or similar material as the shell 1, either welded or integrally cast.

[0043] The interior of the swirl guide shroud 91 is uniformly equipped with six swirl plates 911 (N=6) along the circumference. These six swirl plates 911 are evenly distributed circumferentially, dividing the cavity of the swirl guide shroud 91 into six 60° spiral channels 912. Each swirl plate 911 is arranged at a helical angle relative to the axial centerline of the swirl guide shroud 91, meaning that each swirl plate 911 extends axially while twisting at a certain angle in the circumferential direction. In this embodiment, the helical angle of the swirl plate 911 is 30°~45°, which can be adjusted according to actual operating conditions.

[0044] The swirl deflector 91 is manufactured using precision casting, forming a single piece. The swirl plate 911 is integrally connected to the inner wall of the swirl deflector 91, ensuring structural strength and dimensional accuracy. The thickness of the swirl plate 911 is 3-8mm, with its inner edge facing the center and its outer edge fixedly connected to the inner wall of the swirl deflector 91. The surface of the swirl plate 911 needs to be polished to reduce fluid flow resistance.

[0045] The buffer cavity 92 is located between the outlet of the tube distribution mechanism 9 and the inlet of the coiled tube bundle 3, that is, in the annular gap cavity between the outlet end of the vortex guide shroud 91 and the tube sheet 2. The axial width of the buffer cavity 92 is determined according to the number of layers and the diameter of the coiled tube bundle 3. In this embodiment, the axial width of the buffer cavity 92 is 1 / 4 of the axial length of the vortex guide shroud 91.

[0046] A sealing structure is provided between the buffer chamber 92 and the tube sheet 2 to ensure that the tube-side medium does not leak to the shell side.

[0047] like Figure 1 and Figure 2 As shown, a conical guide core 93 is also provided inside the swirl guide shroud 91. The conical guide core 93 is located at the center of the swirl guide shroud 91, and it is streamlined and conical, with the tip of the cone pointing towards the tube inlet 5. The diameter of the large end of the conical guide core 93 matches the diameter of the central cylinder 4, and is used to shield the ineffective flow area in the middle of the central cylinder 4, guiding the medium to be evenly distributed in the circumferential spiral channels 912. The conical guide core 93 is fixed to the tube sheet 2. The conical guide core 93 is made of stainless steel, and its surface is polished to reduce fluid resistance.

[0048] In this embodiment of the wound-tube heat exchanger, the heat exchange tube 31 is a reinforced heat transfer tube. For example... Figure 6As shown, the inner wall of the heat exchange tube 31 is provided with spiral microribs 311, with a rib height of 0.3 mm and a pitch of 5 mm. The spiral microribs 311 are formed by precision rolling and electrochemical polishing, and their cross-section is trapezoidal or triangular, used to disrupt the boundary layer inside the tube and increase the heat transfer coefficient inside the tube. The outer wall of the heat exchange tube 31 is wound with spiral fins 312, with a fin height of 4.5 mm and a fin spacing of 8 mm. The spiral fins 312 are fixed to the outer wall of the heat exchange tube 31 by high-frequency welding and stress relief process, and their material is copper or aluminum, used to expand the heat transfer area outside the tube.

[0049] like Figure 1 , Figure 4 and Figure 5 As shown, a shell-side distribution mechanism 10 is provided at the shell-side inlet 7. The shell-side distribution mechanism 10 includes an internally extending annular inlet pipe 101 and multiple rows of jet holes 102 disposed on the wall of the internally extending annular inlet pipe 101. The internally extending annular inlet pipe 101 extends radially into the interior of the shell 1 from the side wall of the shell 1.

[0050] In some implementations, such as Figure 4 and Figure 7 As shown, the extended annular inlet pipe 101 is evenly divided into four non-interconnected annular inlet pipe sections 101a along the axial direction. Correspondingly, the shell-side inlet 7 is also evenly divided into four non-interconnected shell-side inlet branches 701. Each shell-side inlet branch 701 is connected to its corresponding annular inlet pipe section 101a via an independent connecting pipe, thereby achieving the diversion of the shell-side medium into four circumferential regions. This structure allows the shell-side medium to be circumferentially diverted into four streams before entering the shell, effectively avoiding uneven circumferential distribution caused by single-point feeding. Combined with the multi-directional jetting effect of the jet orifice 102, it further improves the circumferential uniformity of the shell-side fluid.

[0051] The jet orifices 102 comprise three rows arranged axially along the inner annular inlet pipe 101: the first row of jet orifices 103 jets flow in a straight upward direction, the second row of jet orifices 104 jets flow in an oblique upward direction of approximately 60°, and the third row of jet orifices 105 jets flow in an oblique upward direction of approximately 30°. Each row contains 30 to 50 jet orifices 102, evenly distributed circumferentially along the inner annular inlet pipe 101. The three rows of jet orifices 102 simultaneously jet from three different directions, achieving omnidirectional coverage of the shell-side space.

[0052] An annular distribution structure 11 is provided at the shell-side outlet 8. The annular distribution structure 11 is an annular channel disposed between the inner wall of the shell 1 and the outer wall of the tube bundle 3. The annular distribution structure 11 has distribution holes or guide vanes (not shown in the figure) inside to eliminate the flow dead zone on the shell-side outlet side. Preferably, the structure of the annular distribution structure 11 is the same as the structure of the shell-side distribution mechanism 10.

[0053] The working process of this embodiment The operating method of the tube-side inlet self-equalizing flow wound tube heat exchanger in this embodiment includes the following steps: S1: Tube-side medium inlet entry and swirl generation. The tube-side medium enters the tube-side distribution mechanism 9 through the tube-side inlet 5. The medium first enters the swirl guide shroud 91, and under the guidance of six swirl plates 911, it is forced to flow along six 60° spiral channels 912. Since each swirl plate 911 is set at a helical angle relative to the axial centerline, the medium generates swirl motion when flowing through the spiral channels 912. The swirl intensity can be controlled by adjusting the helical angle of the swirl plates 911. In this embodiment, the swirl intensity can be adjusted by replacing the swirl guide shroud 91 with different helical angles.

[0054] The conical guide core 93 shields the ineffective flow area in the center corresponding to the central cylinder 4, and guides the medium to be evenly distributed in the circumferential spiral channels 912, so as to avoid the formation of ineffective flow of the medium in the central area.

[0055] S2: Formation of a circumferential velocity gradient distribution. The swirling motion causes a circumferential velocity gradient distribution of the tube-side medium at the outlet of the swirling guide shroud 91—high linear velocity at the periphery and low linear velocity at the center. Specifically, the linear velocity of the medium near the inner wall of the shell 1 is higher, corresponding to the inlet region of the outer heat exchange tubes 31 of the tube bundle 3; the linear velocity of the medium near the central cylinder 4 is lower, corresponding to the inlet region of the inner heat exchange tubes 31 of the tube bundle 3.

[0056] S3: Buffering and Smooth Transition. The swirling medium, accelerated by the swirling guide shroud 91, enters the buffer chamber 92. Within the buffer chamber 92, the high-velocity gradient swirling flow field develops and transitions smoothly. Simultaneously, the annular cavity structure of the buffer chamber 92 fine-tunes the circumferential local flow deviation, making the flow field at the inlet of each heat exchange tube 31 more uniform and stable. The buffering process in the buffer chamber 92 maintains the velocity gradient distribution formed by the swirling motion while preserving the velocity difference between the outer and inner media.

[0057] S4: Flow rate equalization. After flowing out of the buffer chamber 92, the tube-side media with different linear velocity distributions enter their respective layers of heat exchange tubes 31 on the tube sheet 2. The media in the outer heat exchange tubes 31 achieves higher local dynamic pressure due to its higher inlet linear velocity, compensating for the additional friction loss caused by the increased tube length. The total pressure drop at the inlet of each heat exchange tube 31 tends to be consistent, resulting in a balanced flow rate distribution within each heat exchange tube 31. Actual testing shows that the flow rate distribution deviation between the heat exchange tubes 31 in this embodiment is ≤5%.

[0058] S5: Shell-side medium inflow and distribution. The shell-side medium enters the shell-side distribution mechanism 10 through the shell-side inlet 7. The shell-side medium first enters the internally extended annular inlet pipe 101, and then flows simultaneously through three rows of jet holes 102 in the upward, 60° upward, and 30° upward directions, respectively, achieving omnidirectional coverage of the shell-side space. The shell-side medium is uniformly distributed from the beginning of its entry into the shell 1, effectively eliminating the dead zone in the flow field directly opposite the inlet of a traditional non-internally extended inlet pipe.

[0059] S6: Heat Exchange. The tube-side medium flows through each layer of heat exchange tubes 31, while the shell-side medium flows within the shell 1. Heat exchange occurs between the two through the tube walls of the heat exchange tubes 31. The tube-side medium transfers heat to the shell-side medium (or vice versa), achieving heat transfer. With a balanced flow rate distribution across the tubes, the flow velocity of the medium within each heat exchange tube 31 is within a reasonable range, allowing the enhanced heat transfer effect of the spiral microribs 311 and spiral fins 312 to be fully utilized. In this embodiment, the overall heat transfer efficiency is improved by approximately 40% compared to traditional wound-tube heat exchangers.

[0060] S7: Medium outflow. After heat exchange is completed, the tube-side medium collects at tube outlet 6 and flows out; the shell-side medium flows through the entire length of the tube bundle 3 and then collects at shell outlet 8 via the annular distribution structure 11. The annular distribution structure 11 further eliminates the flow dead zone on the shell-side outlet side.

[0061] Example 2 The difference between this embodiment and Embodiment 1 is that the number of swirl plates N=4 within the swirl guide shroud 91. The four swirl plates 911 are evenly distributed circumferentially, uniformly dividing the cavity of the swirl guide shroud 91 into four 90° spiral channels 912. This embodiment is suitable for applications with a small number of pipe layers (e.g., 2-3 layers), where a smaller velocity gradient is required, and the four swirl plates 911 are sufficient to achieve uniform flow distribution and velocity gradient control. Other structures and operating methods in this embodiment are the same as in Embodiment 1 and will not be repeated here.

[0062] Example 3 The difference between this embodiment and Embodiment 1 is that the number of swirl plates N=8 within the swirl guide shroud 91. Eight swirl plates 911 are evenly distributed circumferentially, uniformly dividing the cavity of the swirl guide shroud 91 into eight 45° spiral channels 912. This embodiment is suitable for applications with a large number of tube layers (e.g., 6-8 layers), where more precise circumferential flow splitting and velocity gradient control are required; the eight swirl plates 911 achieve better uniform distribution. Other structures and operating methods in this embodiment are the same as in Embodiment 1 and will not be repeated here.

[0063] Example 4 The difference between this embodiment and Embodiment 1 is that the axial width of the buffer chamber 92 is 1 / 5 of the axial length of the swirl guide shroud 91. The narrower buffer chamber 92 is suitable for applications with low viscosity and good flowability, where the medium can smoothly enter the heat exchange tube 31 without requiring an excessively long buffering distance. Other structures and operating methods in this embodiment are the same as in Embodiment 1 and will not be repeated here.

[0064] Example 5 The difference between this embodiment and Embodiment 1 is that the axial width of the buffer cavity 92 is 1 / 3 of the axial length of the swirl guide shroud 91. The wider buffer cavity 92 is suitable for working conditions with high viscosity and poor fluidity of the medium, where a longer buffer distance is required to achieve sufficient flow field development and circumferential homogenization. Other structures and operating methods in this embodiment are the same as in Embodiment 1 and will not be repeated here.

[0065] Example 6 The difference between this embodiment and Embodiment 1 is that the tube distribution mechanism 9 does not include the buffer chamber 92. The outlet end of the swirling guide shroud 91 is directly opposite to the tube sheet 2, and the swirling medium accelerated by the swirling guide shroud 91 directly enters each heat exchange tube 31. This embodiment is suitable for operating conditions with strict limitations on installation space or high medium cleanliness, where buffering and flow stabilization are not required. The other structures and operating methods of this embodiment are basically the same as those of Embodiment 1, except that the buffering process in step S3 is omitted.

[0066] Preferred range of process parameters Based on practical engineering applications, the preferred parameter ranges for each component of this invention are as follows: Number of swirl vanes N: N=4~12, preferably N=6. When the number of swirl vanes is too small (N<4), the circumferential flow uniformity is insufficient; when the number of swirl vanes is too large (N>12), the spiral channel is too narrow, increasing the flow resistance.

[0067] The helix angle of the swirl plate is 20°~50°, preferably 30°~40°. When the helix angle is too small (<20°), the swirling intensity is insufficient and an effective velocity gradient cannot be formed; when the helix angle is too large (>50°), the flow resistance increases significantly.

[0068] Swirl plate thickness: 3~10mm, preferably 4~6mm. If the thickness is too thin, the structural strength is insufficient and it is easy to deform during long-term operation; if the thickness is too thick, it increases flow resistance and equipment weight.

[0069] Axial width of the buffer chamber: 1 / 6 to 1 / 2 of the axial length of the vortex guide shroud, preferably 1 / 5 to 1 / 3. If the width is too small, the buffering effect will be insufficient; if the width is too large, it will increase the axial dimension of the equipment and waste space.

[0070] The height of the helical microribs is 0.2~0.5mm, preferably 0.3~0.4mm. If the rib height is too small, the boundary layer disruption will be insufficient; if the rib height is too large, the flow resistance will increase.

[0071] Spiral microrib pitch: 3~8mm, preferably 4~6mm.

[0072] Spiral fin height: 3~6mm, preferably 4~5mm.

[0073] Spiral fin spacing: 5~10mm, preferably 6~8mm.

[0074] Industrial Application Notes This invention can be widely applied to heat exchange processes in the following industrial fields: In the field of natural gas liquefaction: it serves as the main cryogenic heat exchanger in large-scale natural gas liquefaction plants, handling the heat exchange of multiple fluid streams.

[0075] In the petrochemical industry: it is used for heat recovery and cold energy utilization in the cryogenic separation process of petrochemicals.

[0076] In the field of air separation: used for heat and cold exchange in air separation units.

[0077] In the field of marine engineering: heat exchange equipment used in offshore floating liquefied natural gas production, storage and offloading facilities, especially suitable for offshore swaying conditions.

[0078] Other cryogenic engineering fields: heat exchange equipment for processes such as hydrogen liquefaction and rare gas separation.

[0079] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. 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 spirit and scope of the present invention. Any modifications, equivalent substitutions, improvements, etc., should be included within the protection scope of the present invention.

Claims

1. A tube-side inlet self-equalizing wound tube heat exchanger, comprising a shell (1), a tube sheet (2), a wound tube bundle (3), and a central cylinder (4), wherein the wound tube bundle (3) is composed of multiple heat exchange tubes (31) wound around the outside of the central cylinder (4), and in each layer of heat exchange tubes (31), the tube length of the outer layer of heat exchange tubes is greater than that of the inner layer of heat exchange tubes, characterized in that, Also includes: A tube-side distribution mechanism (9) is installed at the tube-side inlet (5) and includes a swirl guide shroud (91); The swirling guide hood (91) has N swirling plates (911) uniformly arranged circumferentially inside, where N≥4. The N swirling plates (911) uniformly divide the cavity of the swirling guide hood (91) into N spiral channels (912). The N swirl plates (911) are arranged at a helical angle relative to the axial center line of the swirl guide shroud (91), guiding the medium flowing through the swirl guide shroud (91) to generate swirling motion, so that the linear velocity of the medium at the inlet of the outer heat exchange tube is greater than that at the inlet of the inner heat exchange tube.

2. The tube-side inlet self-equalizing wound-tube heat exchanger according to claim 1, characterized in that, The number of swirl plates (911) is N=6. The six swirl plates (911) are evenly distributed circumferentially, which evenly divides the cavity of the swirl guide hood (91) into six spiral channels (912).

3. A tube-side inlet self-equalizing wound-tube heat exchanger according to claim 1, characterized in that, The tube distribution mechanism (9) further includes a buffer chamber (92), which is located between the outlet of the tube distribution mechanism (9) and the inlet of the tube bundle (3).

4. A tube-side inlet self-equalizing wound-tube heat exchanger according to claim 1, characterized in that, The swirling flow guide shroud (91) is also provided with a conical flow guide core (93), which is located at the center of the swirling flow guide shroud (91) to shield the ineffective flow area in the middle of the central cylinder (4) and guide the medium to be evenly distributed in each circumferential spiral channel (912).

5. A tube-side inlet self-equalizing wound-tube heat exchanger according to claim 1, characterized in that, The heat exchange tube (31) is an enhanced heat transfer tube with spiral microribs (311) on the inner wall. The height of the spiral microribs (311) is 0.2~0.5mm and the pitch is 3~8mm. The heat exchange tube (31) has spiral fins (312) wound around its outer wall. The spiral fins (312) have a fin height of 3~6mm and a fin spacing of 5~10mm.

6. A tube-side inlet self-equalizing wound-tube heat exchanger according to claim 1, characterized in that, A shell-side distribution mechanism (10) is provided at the shell-side inlet (7). The shell-side distribution mechanism (10) includes an inwardly extending annular inlet pipe (101) and multiple rows of jet holes (102) provided on the pipe wall of the inwardly extending annular inlet pipe (101). The inwardly extending annular inlet pipe (101) extends from the side wall of the shell (1) into the interior of the shell (1). The multiple rows of jet holes (102) are evenly distributed along the axial and circumferential directions of the inwardly extending annular inlet pipe (101). The multi-row jet orifice (102) includes three rows of jet orifices arranged axially along the inner-extended annular inlet pipe (101), with the jet directions of the three rows of jet orifices being the upward direction, the oblique upward direction at 60°, and the oblique upward direction at 30°, respectively.

7. A tube-side inlet self-equalizing wound-tube heat exchanger according to claim 6, characterized in that, An outlet annular uniform distribution structure (11) is provided at the shell-side outlet (8) to eliminate the flow dead zone on the shell-side outlet side; The internally extended annular inlet pipe (101) is divided into multiple non-interconnected annular inlet pipe sections (101a) along the axial direction. The shell-side inlet (7) is also divided into the same number of non-interconnected shell-side inlet branches (701). Each shell-side inlet branch (701) is connected to the corresponding annular inlet pipe section (101a) through an independent connecting pipe.

8. A method for operating a tube-side inlet self-equalizing flow wound tube heat exchanger, employing the tube-side inlet self-equalizing flow wound tube heat exchanger as described in any one of claims 1 to 7, characterized in that, Includes the following steps: S1: The tube-side medium enters the tube-side distribution mechanism (9) from the tube-side inlet (5) and is guided by each spiral channel (912) to generate swirling motion when it flows through the swirling guide shroud (91); S2: The swirling motion causes the tube-side medium to form a circumferential velocity gradient distribution at the outlet of the tube-side distribution mechanism (9), and the linear velocity of the medium in the inlet region of the outer heat exchange tube is greater than that of the medium in the inlet region of the inner heat exchange tube. S3: The tube-side medium with different linear velocity distribution enters each of the corresponding heat exchange tubes (31). The medium in the outer heat exchange tube compensates for the additional friction loss caused by the increase in tube length by the higher inlet linear velocity, so that the flow rate of the medium in each heat exchange tube (31) tends to be consistent. S4: After the tube-side medium flows through each heat exchange tube (31) and exchanges heat with the shell-side medium, it is collected at the tube-side outlet (6) and flows out.

9. The operating method of a tube-side inlet self-equalizing wound-tube heat exchanger according to claim 8, characterized in that, In step S1, the swirling intensity of the swirling motion is controlled by adjusting the helix angle of the swirling plate (911) to match the friction resistance compensation requirements under different tube winding layers and different tube length ratios.

10. The operating method of a tube-side inlet self-equalizing wound-tube heat exchanger according to claim 8, characterized in that, When the tube-side distribution mechanism (9) further includes a buffer cavity (92) disposed between its outlet and the inlet of the coiled tube bundle (3), the tube-side medium, after being distributed by the swirling flow guide shroud (91), first enters the buffer cavity (92), and while maintaining the velocity gradient distribution formed by the swirling motion, it is buffered and mixed again before entering each layer of heat exchange tubes (31).

Images