Double-layer heat exchange tube and shell-and-tube heat exchanger

Abstract

The invention relates to the technical field of heat exchangers, and particularly discloses a double-layer heat exchange tube and a shell-and-tube heat exchanger, the double-layer heat exchange tube comprises an inner tube and an outer tube, the inner tube is sleeved in the outer tube, an interlayer is formed between the inner tube and the outer tube, communicating ends are arranged at the parts, close to the two ends of the inner tube, in the interlayer, and the communicating ends are communicated with the inner tube. A plurality of communicating ends are arranged at intervals in the circumferential direction, the communicating ends are connected with the outer wall of the inner pipe and the inner wall of the outer pipe in a sealed mode, a penetrating-connecting cavity is formed between every two adjacent communicating ends in the circumferential direction, plugging heads are arranged at the two ends of the inner pipe, and flow guide holes are formed in the outer walls, close to the two ends, of the outer pipe. The flow guide holes penetrate through the communicating end in the radial direction and then communicate with the interior of the inner pipe. Due to the fact that the heat exchange tube is of the double-layer structure, fluid on one side flows inside and outside the tube while flowing, fluid on the other side circulates in the interlayer, the heat exchange area in unit volume is greatly increased, the heat exchange efficiency is improved, and the equipment volume is reduced under the same heat exchange capacity.

Description

Technical Field

[0001] This invention relates to the field of heat exchanger equipment technology, specifically to a double-layer heat exchange tube and a shell-and-tube heat exchanger. Background Technology

[0002] A heat exchanger is a device that transfers some of the heat from a hot fluid to a cold fluid; it is also called a heat exchanger. Heat exchangers play an important role in chemical, petroleum, power, food, and many other industrial production processes. Heat exchangers can be classified into various types according to their structure, with shell-and-tube heat exchangers being one such type.

[0003] This heat exchanger structure is as follows Figure 1 As shown, it mainly includes heat exchange tubes 15, a cylinder 12, and end caps 14 at both ends. The heat exchange tubes 15 are bidirectionally connected, with both ends welded to the tube sheet 13. Fluid from one side enters through the end cap 14 at one end, passes through the interior of the heat exchange tubes 15, and flows out through the end cap 14 at the other end. Fluid from the other side enters through the inlet on one side of the cylinder 12, exchanges heat with the outer wall of the heat exchange tubes 15, and flows out through the outlet on the other side of the cylinder 12.

[0004] The aforementioned heat exchange tubes can be curved or straight. During operation, the fluid enters from one end of the heat exchange tube and flows out from the other end. The internal fluid exchanges heat with the external medium through the tube wall. Currently, heat exchange tubes are generally single-layer structures, with a cross-section as shown in the figure. Figure 2 As shown. Single-layer heat exchange tubes have lower manufacturing costs, but their disadvantage is that the heat exchange area is related to the tube diameter for a given length. Once the tube diameter is determined, the heat exchange area per unit volume cannot be increased. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of single-layer heat exchange tubes used in current shell-and-tube heat exchangers by providing a double-layer heat exchange tube and a shell-and-tube heat exchanger. The heat exchange tube has a double-layer structure, with fluid flowing both inside and outside the tube on one side, while fluid flows in the interlayer on the other side. This increases the heat exchange area within a single volume, which is beneficial for improving heat exchange efficiency.

[0006] This invention is achieved through the following technical solution: In a first aspect, the present invention provides a double-layer heat exchange tube, comprising an inner tube and an outer tube, wherein the inner tube is sleeved within the outer tube and an interlayer is formed between the inner tube and the outer tube, wherein a connecting end is provided in the interlayer near both ends of the inner tube, and multiple connecting ends are spaced apart circumferentially at each end, wherein the connecting end forms a sealed connection with the outer wall of the inner tube and the inner wall of the outer tube, and a through cavity is formed between two adjacent connecting ends in the circumferential direction, wherein a sealing head is provided at both ends of the inner tube, and a flow guide hole is provided on the outer wall near both ends of the outer tube, and the flow guide hole passes radially through the connecting end and communicates with the interior of the inner tube.

[0007] In the above scheme, a jacket is formed between the inner and outer tubes of the heat exchanger tubes and connected by a connecting end. The inner tube has plugs at both ends to allow fluid to flow into the jacket. The outer tube has guide holes on its outer walls at both ends, which radially pass through the connecting end and communicate with the interior of the inner tube. During operation, fluid on one side flows outside the outer tube and simultaneously enters the inner tube through the guide holes. Fluid on the other side flows through the jacket between the inner and outer tubes via the connecting cavity. During heat exchange, the fluid in the jacket simultaneously exchanges heat with the fluids on the outside of the outer tube and the inside of the inner tube, greatly increasing the heat exchange area per unit volume, improving heat exchange efficiency, and reducing the equipment size for the same heat exchange capacity.

[0008] As a further aspect of the present invention, the interlayer has a rack arranged axially in the middle of the inner tube, and multiple racks are spaced apart circumferentially. The racks form a sealed connection with both the outer wall of the inner tube and the inner wall of the outer tube, and a flow-dividing cavity is formed between two adjacent racks circumferentially. By arranging multiple racks circumferentially between the inner and outer tubes, with the racks located in the interval between the connecting ends, and a flow-dividing cavity formed between two adjacent racks, the fluid, after entering the outer tube, can flow through the through-hole at one end to each flow-dividing cavity, thus improving the heat exchange effect.

[0009] As a further embodiment of the present invention, the axial length of the rack is less than the inner spacing distance between the connecting ends at both ends of the inner tube, and an annular connecting cavity is formed between the end of the rack and the inner side of the adjacent connecting end.

[0010] By forming an annular connecting cavity between the end of the rack and the inner side of the adjacent connecting end, after the fluid enters the outer tube, it can enter the connecting cavity at one end through the through-cavity at one end, and then flow from the connecting cavity to each branch cavity. Similarly, after the fluid leaves the branch cavity, it flows into the connecting cavity at the other end, and then flows out of the outer tube through the through-cavity at the other end. The two connecting cavities mentioned above can play a fluid buffering role, which is conducive to the fluid entering the branch cavity or the through-cavity.

[0011] As a further aspect of the present invention, the rack and the inner tube are integrally formed, and the rack and the inner wall of the outer tube are connected together by diffusion welding. By integrating the rack structure onto the outer wall of the inner tube and connecting the rack and the inner wall of the outer tube by diffusion welding, the production and manufacturing of the double-layer heat exchange tube can be facilitated, while the heat transfer efficiency and the overall strength of the double-layer heat exchange tube can be improved.

[0012] As a further aspect of the present invention, the rack is evenly distributed circumferentially, and the resulting flow distribution cavities have the same volume and symmetrical positions, which is beneficial to improving the uniformity of heat exchange.

[0013] As a further aspect of the present invention, the connecting end and the inner tube are integrally formed, and the connecting end is connected to the inner wall of the outer tube by diffusion welding. By integrating the connecting end onto the outer wall of the inner tube and connecting the connecting end to the inner wall of the outer tube by diffusion welding, the production and manufacturing of the double-layer heat exchange tube can be facilitated, while the heat transfer efficiency and the overall strength of the double-layer heat exchange tube can be improved.

[0014] As a further aspect of the present invention, the connecting ends are evenly distributed circumferentially, and the resulting through-cavities have the same volume and symmetrical positions, which is beneficial to improving the fluid flow and also to improving the heat exchange effect of the double-layer heat exchange tube.

[0015] As a further aspect of the present invention, the side of the sealing head away from the end of the inner tube is a spherical structure. By designing the outer end of the sealing head as a spherical structure, the fluid can be guided uniformly, reducing resistance loss, and the fluid can smoothly enter the interlayer under the guidance of the spherical surface.

[0016] As a further embodiment of the present invention, the sealing head and the end of the inner tube are sealed by welding or by an assembly structure.

[0017] As a further embodiment of the present invention, the number of the guide holes is the same as the number of the connecting ends distributed circumferentially, and the guide holes are located at the center of each connecting end. With this configuration, the two ends of the double-layer heat exchange tube have multiple guide holes, and each guide hole can be evenly distributed circumferentially, which is beneficial for uniformly guiding the fluid on the outside of the outer tube into and out of the inside of the inner tube, reducing resistance loss, and improving the heat exchange effect.

[0018] As a further aspect of the present invention, both the inner wall of the inner tube and the outer wall of the outer tube are provided with axially oriented protrusions, which are uniformly distributed circumferentially. By providing multiple protrusions on the inner wall of the inner tube and the outer wall of the outer tube, the heat exchange capacity between the inner and outer tubes and the fluid can be further enhanced.

[0019] In a second aspect, the present invention provides a shell-and-tube heat exchanger, comprising a shell, a tube sheet, end caps, and a double-layer heat exchange tube as described in any one of the first aspects. The tube sheet is respectively sealed to both ends of the shell, and the end caps are respectively sealed to the outside of the tube sheet. The two ends of the outer tube in the double-layer heat exchange tube are sealed to the tube sheet, and the two ends of the outer tube communicate with the inside of the end caps. The shell is provided with a primary fluid inlet pipe and a primary fluid outlet pipe, and the two end caps are respectively provided with a secondary fluid inlet pipe and a secondary fluid outlet pipe.

[0020] Because this shell-and-tube heat exchanger uses the aforementioned double-layer heat exchange tubes, the primary-side fluid enters the shell and flows outside the outer tube, while simultaneously flowing into the inner tube through the guide holes. The secondary-side fluid enters the end cap and flows through the through-cavity between the inner and outer tubes. During heat exchange, the secondary-side fluid in the jacket exchanges heat with both the primary-side fluid on the outside of the outer tube and the inside of the inner tube, greatly increasing the heat exchange area per unit volume, improving the heat exchanger's efficiency, and reducing the size of the heat exchange equipment for the same heat exchange capacity.

[0021] Compared with the prior art, the present invention has the following advantages and beneficial effects: The double-layer heat exchange tube of this invention includes an inner tube and an outer tube, with an interlayer formed between them and connected by a connecting end. The inner tube has end caps at both ends, and the outer tube has flow guide holes on its outer wall near both ends, which radially pass through the connecting end and communicate with the interior of the inner tube. During operation, fluid on one side flows outside the outer tube and simultaneously enters the inner tube through the flow guide holes. Fluid on the other side flows through the interlayer between the inner and outer tubes via the connecting cavity. During heat exchange, the fluid in the interlayer simultaneously exchanges heat with the fluids on the outside of the outer tube and the inside of the inner tube, greatly increasing the heat exchange area per unit volume, improving heat exchange efficiency, and reducing the equipment size for the same heat exchange capacity. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings: Figure 1 This is a schematic diagram of a traditional shell-and-tube heat exchanger. Figure 2 This is a schematic diagram of a traditional heat exchanger tube cross-section; Figure 3 This is a schematic diagram of the main cross-section of the double-layer heat exchange tube in this invention; Figure 4 For the present invention Figure 3 Schematic diagram of AA section in the middle; Figure 5 For the present invention Figure 3 Schematic diagram of the BB cross section in the middle; Figure 6 For the present invention Figure 3 Schematic diagram of the CC section in the image; Figure 7 This is a schematic diagram of the main cross-section of the shell-and-tube heat exchanger in this invention.

[0023] The attached diagram shows the markings and corresponding component names: 1-Outer tube; 2-Connecting end; 3-Flow guide hole; 4-Connecting cavity; 5-Inner tube; 6-Sealing head; 7-Rack; 8-Through-connecting cavity; 9-Contact part; 10-Flow splitting cavity; 11-Protrusion; 12-Cylinder; 13-Tube sheet; 14-End cap; 15-Heat exchange tube; 16-Primary side fluid inlet pipe; 17-Primary side fluid outlet pipe; 18-Secondary side fluid inlet pipe; 19-Secondary side fluid outlet pipe. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0026] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly indicating the number, specific order, or primary and secondary relationship of the indicated technical features.

[0027] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0028] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A exists, A and B exist simultaneously, and B exists. In addition, the character " / " in this document generally indicates that the related objects before and after it have an "or" relationship.

[0029] In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0030] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces), unless otherwise explicitly specified.

[0031] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0032] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," 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. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0033] The traditional shell-and-tube heat exchanger structure mainly includes heat exchange tubes, a shell, and end caps at both ends. The heat exchange tubes are bidirectionally connected, with both ends welded to the tube sheet. Fluid from one end enters through the heat exchange tube from one end cap and flows out from the other end cap, while fluid from the other end enters from one side of the shell, exchanges heat with the outer wall of the heat exchange tube, and flows out from the other side.

[0034] Traditional shell-and-tube heat exchangers typically use single-layer heat exchange tubes. While this type of tube has a lower manufacturing cost, its drawback is that the heat exchange area is related to the tube diameter for a given length. Once the tube diameter is determined, the heat exchange area per unit volume cannot be increased, thus affecting the efficiency of the heat exchanger.

[0035] In view of this, after long-term and in-depth research, the applicant invented a heat exchange tube with a double-layer structure. The heat exchange tube has a sandwich between the inner and outer tubes. When the fluid flows on one side, it flows both inside and outside the tube at the same time, while the fluid on the other side flows in the sandwich. This increases the heat exchange area within a single volume, which is beneficial to improving the heat exchange efficiency.

[0036] Please refer to Figures 3 to 7 The double-layer heat exchange tube 15 provided in this embodiment includes an inner tube 5 and an outer tube 1. The inner tube 5 is sleeved in the outer tube 1, and an interlayer is formed between the inner tube 5 and the outer tube 1. A connecting end 2 is provided in the interlayer near both ends of the inner tube 5, and multiple connecting ends 2 are spaced apart circumferentially at each end. The connecting end 2 forms a sealed connection with the outer wall of the inner tube 5 and the inner wall of the outer tube 1. A through cavity 8 is formed between two adjacent connecting ends 2 in the circumferential direction. A sealing head 6 is provided at both ends of the inner tube 5. A guide hole 3 is provided on the outer wall of the outer tube 1 near both ends, and the guide hole 3 passes radially through the connecting end 2 and communicates with the inside of the inner tube 5.

[0037] The inner tube 5 and the outer tube 1 are arranged coaxially, that is, the axis of the inner tube 5 coincides with the axis of the outer tube 1, and a sandwich is formed between the inner tube 5 and the outer tube 1. That is, the diameter of the outer wall of the inner tube 5 is smaller than the diameter of the inner wall of the outer tube 1, and there is a certain gap between the two to allow fluid to flow.

[0038] The connecting end 2 is located between the outer wall of the inner tube 5 and the inner wall of the outer tube 1, forming a sealed connection with the inner tube 5 and the outer tube 1, connecting the inner tube 5 and the outer tube 1 into a whole. The thickness of the connecting end 2 is the radial gap value between the inner tube 5 and the outer tube 1. Multiple connecting ends 2 are provided on the outer wall of the inner tube 5 near both ends. The connecting ends 2 at each end are arranged circumferentially, and a through cavity 8 is formed between adjacent connecting ends 2, through which the fluid in the outer tube 1 can pass.

[0039] The outer tube 1 has open ends, and the inner tube 5 is sealed at both ends with plugs 6. The outer tube 1 has guide holes 3 on its outer wall near both ends. These guide holes 3 pass radially through the connecting end 2 and communicate with the interior of the inner tube 5. Fluid on one side can enter from one end of the outer tube 1 and flow along the interlayer, then exit from the other end. Fluid on the other side can flow through the guide holes 3 while flowing outside the outer tube 1, thus entering the interior of the inner tube 5.

[0040] The double-layer heat exchange tube 15 in this application includes an inner tube 5 and an outer tube 1. An interlayer is formed between the inner tube 5 and the outer tube 1, and they are connected by a connecting end 2. The inner tube 5 has sealing heads 6 at both ends, and the outer tube 1 has flow guide holes 3 on its outer wall near both ends. These flow guide holes 3 radially pass through the connecting end 2 and communicate with the interior of the inner tube 5. During operation, fluid on one side flows outside the outer tube 1 and simultaneously enters the interior of the inner tube 5 through the flow guide holes 3. Fluid on the other side flows through the interlayer between the inner tube 5 and the outer tube 1 via the through-hole 8. During heat exchange, the fluid in the interlayer simultaneously exchanges heat with the fluids outside the outer tube 1 and inside the inner tube 5, greatly increasing the heat exchange area per unit volume, improving heat exchange efficiency, and reducing the equipment volume for the same heat exchange capacity.

[0041] According to some embodiments of this application, a rack 7 is provided axially in the middle of the inner tube 5 in the interlayer, and multiple racks 7 are spaced apart circumferentially. The racks 7 form a sealed connection with the outer wall of the inner tube 5 and the inner wall of the outer tube 1. A flow divider cavity 10 is formed between two adjacent racks 7 in the circumferential direction.

[0042] By setting a rack 7 between the inner tube 5 and the outer tube 1, the rack 7 is located in the interval between the connecting ends 2 at both ends, and the rack 7 extends axially and is distributed in multiple circumferential directions. A flow divider 10 is formed between two adjacent racks 7. After the fluid enters the inner tube 1, it can flow to each flow divider 10 through the through-hole 8 at one end, which is beneficial to improving the heat exchange effect.

[0043] According to some embodiments of this application, the axial length of the rack 7 is less than the inner spacing distance between the connecting ends 2 at both ends of the inner tube 5, and an annular connecting cavity 4 is formed between the end of the rack 7 and the inner side of the adjacent connecting end 2.

[0044] An annular connecting cavity 4 is formed between the end of the rack 7 and the inner side of the adjacent connecting end 2. After the fluid enters the outer tube 1, it can enter the connecting cavity 4 at one end through the through cavity 8 at one end, and then flow from the connecting cavity 4 to each branch cavity 10. Similarly, after the fluid leaves the branch cavity 10, it flows into the connecting cavity 4 at the other end, and then flows out of the outer tube 1 through the through cavity 8 at the other end. The two connecting cavities 4 mentioned above can play a fluid buffering role, which is conducive to the fluid entering the branch cavity 10 or the through cavity 8.

[0045] According to some embodiments of this application, the rack 7 and the inner tube 5 are integrally formed, and the rack 7 and the inner wall of the outer tube 1 are connected together by diffusion welding.

[0046] By integrating the rack 7 structure onto the outer wall of the inner tube 5 and connecting the rack 7 to the inner wall of the outer tube 1 through diffusion welding, the production and manufacturing of the double-layer heat exchange tube 15 can be facilitated, while the efficiency of heat transfer and the overall strength of the double-layer heat exchange tube 15 can be improved.

[0047] According to some embodiments of this application, the racks 7 are uniformly distributed circumferentially. By uniformly distributing the racks 7 circumferentially, the resulting flow distribution cavities 10 have the same volume and symmetrical positions, which helps to improve the uniformity of heat transfer.

[0048] According to some embodiments of this application, the connecting end 2 and the inner tube 5 are integrally formed, and the connecting end 2 and the inner wall of the outer tube 1 are connected together by diffusion welding.

[0049] By integrating the connecting end 2 onto the outer wall of the inner tube 5 and connecting the connecting end 2 to the inner wall of the outer tube 1 through diffusion welding, the production and manufacturing of the double-layer heat exchange tube 15 can be facilitated, while the efficiency of heat conduction and the overall strength of the double-layer heat exchange tube 15 can be improved.

[0050] It should be noted that the above-mentioned diffusion welding is a solid-state joining technology in metallurgical engineering. It achieves reliable joining of the same or different materials by causing atomic diffusion on the surface of the material under high temperature and pressure to form an interfacial bonding layer. It is mainly divided into two categories: solid-state diffusion welding and instantaneous liquid-state diffusion welding, and is suitable for welding materials such as ceramics and metals.

[0051] This technology comprises three stages: physical contact, atomic diffusion, and bonding layer expansion. The core parameters are temperature, pressure, and time. Using an intermediate layer can alleviate residual stress in ceramic / metal welding and improve wettability. Spark plasma sintering technology, due to its low-temperature and rapid characteristics, has been used for diffusion welding of alumina ceramics and stainless steel. The superplastic forming / diffusion bonding combination process has enabled near-margin manufacturing of aerospace titanium alloy and aluminum alloy components.

[0052] Transition liquid phase diffusion welding combines the advantages of brazing and diffusion welding, achieving high-performance connections through intermediate layer melting and diffusion. It is applied to novel materials such as intermetallic compounds and single-crystal high-temperature alloys. Plasma-activated low-temperature diffusion welding technology overcomes the challenges of joining amorphous and single-crystal alloys, achieving joint performance exceeding 90% of that of the base material.

[0053] In this application, after the inner tube 5 is inserted into the outer tube 1, the contact part 9 of the two is connected into a whole by diffusion welding. The inner and outer tubes are connected by diffusion welding, which is simple to process and has high reliability.

[0054] According to some embodiments of this application, the connecting ends 2 are uniformly distributed circumferentially. By uniformly distributing the connecting ends 2 circumferentially, the resulting through-cavities 8 have the same volume and symmetrical positions, which is beneficial to improving fluid flow and also enhances the heat exchange effect of the double-layer heat exchange tube 15.

[0055] According to some embodiments of this application, the side of the plugging head 6 away from the end of the inner tube 5 is a spherical structure. By designing the outer end of the plugging head 6 as a spherical structure, the fluid can be guided uniformly, reducing resistance loss, and the fluid can smoothly enter the interlayer under the guidance of the spherical surface.

[0056] According to some embodiments of this application, the sealing head 6 and the end of the inner tube 5 are sealed by welding or by an assembly structure. The sealing head 6 is mainly used to seal the end opening of the inner tube 5, allowing fluid to pass through the interlayer.

[0057] Specifically, the structure of the aforementioned plug head 6 may include a plug section and a spherical end located at one end of the plug section. During installation, the plug section is inserted into the opening of the inner tube 5, so that one side of the spherical end is tightly against the end face of the inner tube 5. The plug head 6 and the end of the inner tube 5 can be sealed by welding, for example, by sealing the outer edge of the spherical end to the end of the inner tube 5 with a circumferential weld. Alternatively, the plug head 6 and the end of the inner tube 5 can also be sealed by an assembly structure, for example, by designing the plug section of the plug head 6 and the inner wall of the inner end as an interference fit, and assembling the two by press-fitting.

[0058] According to some embodiments of this application, the number of guide holes 3 is the same as the number of connecting ends 2 distributed circumferentially, and the guide holes 3 are located at the center of each connecting end 2. By designing the guide holes 3 at the center of each connecting end 2, the two ends of the double-layer heat exchange tube 15 have multiple guide holes 3, and each guide hole 3 can be evenly distributed circumferentially, which is beneficial for uniformly guiding the fluid outside the outer tube 1 into and out of the inner tube 5, reducing resistance loss, and improving the heat exchange effect.

[0059] According to some embodiments of this application, a plurality of protrusions 11 are provided axially on the inner wall of the inner tube 5 and the outer wall of the outer tube 1, and the protrusions 11 are evenly distributed circumferentially. By providing a plurality of protrusions 11 on the inner wall of the inner tube 5 and the outer wall of the outer tube 1, the heat exchange capacity between the inner tube 5 and the outer tube 1 and the fluid can be further enhanced.

[0060] It should be noted that the cross-sectional shape of the aforementioned protrusion 11 can be of various configurations, such as rectangular, square, triangular, semi-cylindrical, etc., and is not limited here.

[0061] The specific manufacturing process of the double-layer heat exchange tube 15 in this application is roughly as follows: 1) First, process the outer tube 1, and its outer wall can be kept smooth or processed with protrusions 11.

[0062] 2) Process the connecting end 2 and the rack 7 on the outer wall of the inner tube 5, and make their outer wall dimensions consistent with the inner wall dimensions of the outer tube 1, so that they fit tightly; process the connecting cavity 4 and the through cavity 8 on the outer wall of the inner tube 5, so that their outer wall dimensions are smaller than the inner wall dimensions of the outer tube 1 and maintain a certain gap; the outer wall of the inner tube 5 can be kept smooth or have a protrusion 11 processed on it.

[0063] 3) Insert the inner tube 5 into the outer tube 1, and connect the contact parts 9 of the two into a whole by diffusion welding.

[0064] 4) At the point where the connecting end and the inner wall of the outer tube 1 are diffused and welded, a flow guide hole 3 is processed, with a quantity of no less than two, so that the fluid outside the outer tube 1 can enter and exit the inner tube 5.

[0065] 5) Install sealing heads 6 at both ends of the inner tube 5. They can be welded or otherwise sealed. The ends of the sealing heads 6 are designed with a spherical structure to reduce fluid resistance.

[0066] This application provides a shell-and-tube heat exchanger, including a shell 12, a tube sheet 13, end caps 14, and a double-layer heat exchange tube 15 as described above. The tube sheet 13 is respectively sealed to both ends of the shell 12, and the end caps 14 are respectively sealed to the outside of the tube sheet 13. The two ends of the outer tube 1 in the double-layer heat exchange tube 15 are sealed to the tube sheet 13, and the two ends of the outer tube 1 are in communication with the inside of the end caps 14. The shell 12 is provided with a primary fluid inlet pipe 16 and a primary fluid outlet pipe 17, and the two end caps 14 are respectively provided with a secondary fluid inlet pipe 18 and a secondary fluid outlet pipe 19.

[0067] The aforementioned cylinder 12 is cylindrical, with two tube sheets 13 welded to both ends of the cylinder 12, and two end caps 14 welded to the outer sides of the two tube sheets 13. The outer tube 1 of the double-layer heat exchange tube 15 is welded to the tube sheet 13 at both ends, and the two ends of the outer tube 1 are connected to the inside of the end caps 14. Multiple double-layer heat exchange tubes 15 can be welded onto the aforementioned tube sheet 13. Figure 7 Only one double-layer heat exchange tube 15 is shown in the diagram.

[0068] Because the double-layer heat exchange tube 15 has a double-layer structure including an inner tube 5 and an outer tube 1, the primary-side fluid enters the cylinder 12 and flows outside the outer tube 1, while simultaneously flowing into the inner tube 5 through the guide hole 3. The secondary-side fluid enters the end cap 14 and flows through the through-hole 8 in the interlayer between the inner tube 5 and the outer tube 1. During heat exchange, the secondary-side fluid in the interlayer exchanges heat with the primary-side fluid on the outside of the outer tube 1 and the inside of the inner tube 5, greatly increasing the heat exchange area per unit volume, improving the heat exchange efficiency of the heat exchanger, and reducing the volume of the heat exchange equipment for the same heat exchange capacity.

[0069] Specifically, during operation, the primary fluid A enters the interior of the cylinder 12 through the primary fluid inlet pipe 16 on the cylinder 12, and then splits into two fluids A1 and A2. A1 flows along the outer wall of the outer pipe 1, while A2 enters the inner pipe 5 through the guide hole 3 and flows along the inner pipe 5. Finally, fluid A2 flows out from the guide hole 3 at the other end and merges with fluid A1 before flowing out from the primary fluid outlet pipe 17 of the cylinder 12.

[0070] The secondary fluid B enters the interior of the end cap 14 through the secondary fluid inlet pipe 18 on the end cap 14, and then enters the port of the outer pipe 1. Under the guidance of the plug head 6, the fluid B enters the connecting cavity 4 from the through cavity 8 at one end, then enters the diversion cavity 10, then enters the connecting cavity 4 at the other end, then flows out from the through cavity 8 at the other end, and finally enters the end cap 14 at the other end, and flows out from the secondary fluid outlet pipe 19 on the end cap 14.

[0071] During the above process, the fluid on the side of the cylinder 12 simultaneously exchanges heat with the fluid on both the inner and outer walls of the double-layer heat exchange tube 15 and the fluid in the interlayer. The specific flow paths of fluid A and fluid B are shown in [reference needed]. Figure 7 As shown in the image.

[0072] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A double-layer heat exchange tube, characterized in that, The device includes an inner tube (5) and an outer tube (1). The inner tube (5) is fitted inside the outer tube (1), and a sandwich is formed between the inner tube (5) and the outer tube (1). The sandwich is provided with connecting ends (2) near both ends of the inner tube (5), and multiple connecting ends (2) are spaced apart along the circumference of each end. The connecting ends (2) form a sealed connection with the outer wall of the inner tube (5) and the inner wall of the outer tube (1). A through cavity (8) is formed between two adjacent connecting ends (2) along the circumference. The inner tube (5) is provided with sealing heads (6) at both ends. The outer tube (1) is provided with guide holes (3) on the outer wall near both ends, and the guide holes (3) pass through the connecting ends (2) radially and communicate with the inside of the inner tube (5).

2. The double-layer heat exchange tube according to claim 1, characterized in that, In the interlayer, a rack (7) is provided axially in the middle of the inner tube (5), and multiple racks (7) are provided circumferentially. The racks (7) form a sealed connection with the outer wall of the inner tube (5) and the inner wall of the outer tube (1). A flow divider cavity (10) is formed between two adjacent racks (7) in the circumferential direction.

3. The double-layer heat exchange tube according to claim 2, characterized in that, The axial length of the rack (7) is less than the inner spacing distance between the connecting ends (2) at both ends of the inner tube (5), and an annular connecting cavity (4) is formed between the end of the rack (7) and the inner side of the adjacent connecting end (2).

4. The double-layer heat exchange tube according to claim 2, characterized in that, The rack (7) and the inner tube (5) are integrally formed, and the rack (7) and the inner wall of the outer tube (1) are connected together by diffusion welding.

5. The double-layer heat exchange tube according to claim 2, characterized in that, The rack (7) is evenly distributed circumferentially.

6. The double-layer heat exchange tube according to claim 1, characterized in that, The connecting end (2) and the inner tube (5) are integrally formed, and the connecting end (2) and the inner wall of the outer tube (1) are connected together by diffusion welding.

7. The double-layer heat exchange tube according to claim 1, characterized in that, The connecting ends (2) are evenly distributed circumferentially.

8. The double-layer heat exchange tube according to claim 1, characterized in that, The side of the plug (6) away from the end of the inner tube (5) has a spherical structure.

9. The double-layer heat exchange tube according to claim 1, characterized in that, The sealing head (6) and the end of the inner tube (5) are sealed by welding or by assembly structure.

10. The double-layer heat exchange tube according to claim 1, characterized in that, The number of the guide holes (3) is the same as the number of the connecting ends (2) distributed circumferentially, and the guide holes (3) are located at the center of each connecting end (2).

11. The double-layer heat exchange tube according to claim 1, characterized in that, The inner wall of the inner tube (5) and the outer wall of the outer tube (1) are provided with convex strips (11) along the axial direction, and the convex strips (11) are evenly distributed in the circumferential direction.

12. A shell-and-tube heat exchanger, characterized in that, The device includes a cylinder (12), a tube sheet (13), end caps (14), and a double-layer heat exchange tube as described in any one of claims 1-11. The tube sheet (13) is sealed to both ends of the cylinder (12), and the end caps (14) are sealed to the outside of the tube sheet (13). The two ends of the outer tube (1) in the double-layer heat exchange tube are sealed to the tube sheet (13), and the two ends of the outer tube (1) are connected to the inside of the end caps (14). The cylinder (12) is provided with a primary fluid inlet pipe (16) and a primary fluid outlet pipe (17), and the two end caps (14) are respectively provided with a secondary fluid inlet pipe (18) and a secondary fluid outlet pipe (19).

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