Heat exchange pipe end groove structure and heat exchanger

Abstract

The utility model discloses a heat exchange tube end groove structure and a heat exchanger, the heat exchange tube end groove structure comprises a heat exchange tube and a tube plate, the tube plate is provided with a plurality of tube holes for the heat exchange tube to penetrate through, and the edge of each tube hole is provided with a first groove; the heat exchange tube is coaxially inserted into a tube hole of the tube plate, the tube end of the heat exchange tube extends out of the front end face of the tube plate, a second groove is machined in the inner wall of the tube end of the heat exchange tube, the second groove is an inner V-shaped groove or an inner arc-shaped groove, and the root of the second groove exceeds the front end face of the tube plate; and the heat exchange tube and the tube plate are welded into a whole. The heat exchange tube end groove structure has the advantages that a heat exchange tube end groove structure calculation model is established, grooves are machined in the tube plate and the tube end of the heat exchange tube in combination with the model, the grooves in the tube end are in an inner V shape or an inner arc shape, the tube end appearance of the heat exchange tube is changed, welding stress distribution of the heat exchange tube is changed, tube end cracking and tube opening pollution are effectively prevented, and the heat exchange tube end structure is simple in structure and convenient to operate. The service life of the heat exchanger is prolonged.

Description

Technical Field

[0001] This application relates to the field of welding, and more particularly to a heat exchanger tube end bevel structure and a heat exchanger. Background Technology

[0002] Heat exchanger tubes, as the primary medium for heat exchange, play a crucial role in condensers. Due to their exposure to complex conditions such as corrosion, oxidation, and high pressure, and the influence of equipment vibration, heat exchanger tubes often face the risk of partial or complete failure, which can ultimately affect the normal operation of the heat exchanger. Austenitic stainless steel, with its good toughness, strong weldability, and excellent corrosion resistance, wear resistance, mechanical properties, toughness, and machinability, is a widely chosen material for heat exchanger tubes in the industry, and is extensively used in petroleum, chemical, and medical device industries. However, austenitic stainless steel is highly sensitive to contamination by low-melting-point substances such as copper. Numerous studies and case studies have documented weld cracks and hot-working cracks caused by copper contamination in actual production applications. Traditional heat exchanger tube-to-tubesheet welding methods typically involve passing the heat exchanger tube through the tubesheet, creating a bevel on the tubesheet, and then welding the two together. Under the stress concentration during welding, cracking caused by copper contamination becomes more sensitive and severe, leading to tube end cracking failure, such as… Figure 11 , Figure 12 As shown, the cracks all start from the inside of the pipe end and extend longitudinally along the pipe end thickness and the inner wall.

[0003] like Figures 3-6 As shown, the tube ends of the traditional heat exchange tube 1' in the current tubular heat exchanger equipment are I-bevels 11'. Tube end cracks often occur during the welding of the traditional tube sheet 2', mainly due to stress concentration. The maximum Mises stress caused by welding is concentrated on the inner wall of the tube end. In addition, the I-bevel is prone to contamination of the inner wall of the tube end by the positioning mandrel of the welding equipment. The combination of these two factors makes the possibility of cracking even greater.

[0004] Therefore, there is an urgent need for a heat exchange tube that can effectively change the welding stress distribution, prevent tube end cracks, and reduce or avoid tube end contamination. Utility Model Content

[0005] In view of the shortcomings of the prior art described above, the purpose of this application is to provide a heat exchange tube end bevel structure and heat exchanger to solve the problems of easy cracking at the tube end and easy contamination at the tube opening.

[0006] To solve the above problems, the technical solution adopted in this application is:

[0007] The heat exchange tube end bevel structure described in this application includes a heat exchange tube and a tube sheet, characterized in that: the tube sheet is provided with a plurality of tube holes for inserting the heat exchange tube, and a first bevel is provided at the edge of the tube hole; the heat exchange tube is coaxially inserted into the tube hole of the tube sheet, the tube end of the heat exchange tube extends outward from the front end face of the tube sheet, and a second bevel is processed on the inner wall of the tube end of the heat exchange tube, the second bevel being an inner V-shaped bevel or an inner arc-shaped bevel, and the root of the second bevel extending beyond the front end face of the tube sheet; the heat exchange tube and the tube sheet are welded as a whole.

[0008] As a preferred embodiment of this application, the first bevel is an outwardly inclined inward V-shaped bevel.

[0009] As a preferred embodiment of this application, the height of the first bevel is 1 to 5 mm.

[0010] As a preferred embodiment of this application, the height of the first bevel is 2 mm.

[0011] As a preferred embodiment of this application, the inclination angle of the first bevel is 30° to 60°.

[0012] As a preferred embodiment of this application, the inclination angle of the first bevel is 45°.

[0013] As a preferred embodiment of this application, the second bevel is an outwardly inclined inward V-shaped bevel.

[0014] As a preferred embodiment of this application, the height of the second bevel is 1 / 4 to 3 / 4 of the wall thickness of the heat exchange tube.

[0015] As a preferred embodiment of this application, the heat exchange tube has a wall thickness of 2 mm.

[0016] As a preferred embodiment of this application, the height of the second bevel is 0.5 to 6 mm.

[0017] As a preferred embodiment of this application, the height of the second bevel is 1 mm.

[0018] As a preferred embodiment of this application, the inclination angle θ of the second bevel is 30° to 60°.

[0019] As a preferred embodiment of this application, the inclination angle θ of the second bevel is 45°.

[0020] As a preferred embodiment of this application, the second bevel is an inner arc-shaped bevel, and the inner arc-shaped bevel is concave to the first bevel.

[0021] As a preferred embodiment of this application, the bevel radius of the second bevel is 1 / 2 to 1 / 2 of the wall thickness of the heat exchange tube.

[0022] As a preferred embodiment of this application, the bevel radius of the second bevel is 2 mm.

[0023] As a preferred embodiment of this application, the end of the heat exchange tube extends 3-7 mm beyond the front end face of the tube sheet on the side closest to the tube end.

[0024] As a preferred embodiment of this application, the end of the heat exchange tube extends 5 mm beyond the front end face of the tube sheet on the side closest to the tube end.

[0025] This application also provides a heat exchanger, characterized in that it includes a heat exchange tube end bevel structure manufactured according to the heat exchange tube end bevel structure processing method described in this application or a heat exchange tube end bevel structure as described in this application.

[0026] This application also provides a method for processing the bevel structure at the end of a heat exchanger tube, characterized by including the steps of establishing a calculation model of the bevel structure at the end of the heat exchanger tube and processing the bevel structure at the end of the heat exchanger tube based on the calculation model.

[0027] The steps for establishing a calculation model for the bevel structure of the heat exchanger tube ends include:

[0028] Based on the material properties, dimensional parameters, and installation position parameters of the tube sheet and heat exchange tubes, a geometric model of the heat exchange tube end bevel structure is established in the modeling software. In the geometric model, the edge of the tube hole of the tube sheet is designed with a first bevel, and the inner wall of the tube end of the heat exchange tube is designed with a second bevel.

[0029] The geometric model is divided, and the number of weld passes and layers required for simulating the assembly of tube sheets and heat exchange tubes is determined.

[0030] The welding process of the weld bead is simulated, and a double ellipsoidal heat source model is established; the double ellipsoidal heat source model includes a front half-ellipsoidal heat source model and a rear half-ellipsoidal heat source model;

[0031] The double ellipsoidal heat source model is loaded onto the geometric model for processing, and the solution is obtained based on finite element software to obtain the heat source simulation results; the heat source simulation results include the weld cross-sectional morphology and the temperature field and stress field data of the model changing with time, and the stress deformation field.

[0032] Based on the heat source simulation results, the processing parameters of the heat exchange tube end bevel structure are corrected to ensure that the maximum Mises stress concentration point of the heat exchange tube is moved to the inside of the heat exchange tube, thereby generating the processing parameters of the heat exchange tube end bevel structure; the processing parameters include at least the morphological parameters of the first bevel, the morphological parameters of the second bevel, and the welding relative positions of the first bevel and the second bevel.

[0033] As a preferred embodiment of this application, the steps for fabricating the heat exchanger tube end bevel structure based on the calculation model of the heat exchanger tube end bevel structure include:

[0034] Based on the processing parameters of the modified heat exchanger tube end bevel structure, a first bevel is processed on the edge of the tube hole in the tube sheet, and a second bevel is processed on the inner wall of the heat exchanger tube end.

[0035] The heat exchange tube is coaxially inserted into the tube hole of the tube sheet, and the root of the second bevel of the heat exchange tube is kept beyond the front end face of the tube sheet. The tube sheet and the heat exchange tube are welded at the first bevel. The front end face of the tube sheet and the tube end of the heat exchange tube are connected by the weld, thus completing the assembly and processing of the bevel structure of the heat exchange tube end.

[0036] As a preferred embodiment of this application, the simulation of the weld bead surfacing process and the establishment of a double ellipsoidal heat source model are carried out in the following steps: the weld bead surfacing process is simulated using the birth and death element technique, and the birth and death element subroutine is used to control the movement of the birth and death elements in coordination with the heat source to simulate the material addition process of the weld bead; the heat source subroutine is compiled and imported into the finite element software to establish a double ellipsoidal heat source model.

[0037] As a preferred embodiment of this application, the heat flow expression at any point within the front semi-ellipsoidal heat source model is:

[0038] When 0 ≤ z ≤ h:

[0039]

[0040] When h≤z≤H:

[0041]

[0042] The heat flow expression for any point within the rear hemispherical heat source model is:

[0043] When 0 ≤ z ≤ h:

[0044]

[0045] When h≤z≤H:

[0046]

[0047] In the formula: q(x,y,z) represents the heat flux distribution of the double ellipsoidal heat source model [J / (m 2 ·s)];Q f The heat (W) obtained for the first half of the heat source model; h is the inflection point depth (m); H is the heat source depth (m); l is the scaling factor; z is the z-axis coordinate (m) of the double ellipsoidal heat source model; a1 is the shape parameter of the first half of the ellipsoid; a2 is the shape parameter of the second half of the ellipsoid; b is the shape parameter of the ellipsoid.

[0048] As a preferred embodiment of this application, the second bevel is an outwardly inclined inward V-shaped bevel, the height of the second bevel is 1 / 4 to 3 / 4 of the wall thickness of the heat exchange tube, and the inclination angle θ of the second bevel is 30° to 60°.

[0049] As a preferred embodiment of this application, the height of the second bevel is 1 mm, and the inclination angle θ of the second bevel is 45°.

[0050] As a preferred embodiment of this application, the second bevel is an inner arc-shaped bevel, and the inner arc-shaped bevel is concave to the first bevel.

[0051] As a preferred embodiment of this application, the bevel radius of the second bevel is 1 / 2 to 1 / 2 of the wall thickness of the heat exchange tube.

[0052] As a preferred embodiment of this application, the bevel radius of the second bevel is 2 mm.

[0053] As a preferred embodiment of this application, the number of welding layers is 2. The welding current for the first layer is 120A, the welding voltage is 12V, and the welding speed is 160mm / min. The welding current for the second layer is 122A, the welding voltage is 12V, and the welding speed is 120mm / min.

[0054] As a preferred embodiment of this application, when the first bevel and the second bevel are outwardly inclined inward V-shaped bevels, the bevel parameters include the outer diameter of the heat exchange tube, the wall thickness of the heat exchange tube, the length of the tube end extending out of the tube sheet, the inner diameter of the tube sheet, the height of the first bevel, the inclination angle of the first bevel, the height of the second bevel, and the inclination angle of the second bevel.

[0055] As a preferred embodiment of this application, when the first bevel is an outwardly inclined inner V-shaped bevel and the second bevel is an inner arc-shaped bevel, the bevel parameters include the outer diameter of the heat exchange tube, the wall thickness of the heat exchange tube, the length of the tube end of the heat exchange tube extending out of the tube sheet, the inner diameter of the tube sheet, the height of the first bevel, the inclination angle of the first bevel, and the bevel radius of the second bevel.

[0056] Compared with the prior art, the beneficial effects of this application are: establishing a calculation model of the heat exchange tube end bevel structure, and processing bevels at the tube ends of the tube sheet and heat exchange tubes according to the model; by changing the tube end morphology of the heat exchange tube and the staggered front and back of the bevels to form staggered welding positions, thereby changing the welding stress distribution of the heat exchange tube, so that the welding stress of the heat exchange tube is moved from the inside of the tube end to the inside of the heat exchange tube, effectively preventing tube end cracking and tube opening contamination, and improving the service life of the heat exchanger. Attached Figure Description

[0057] Figure 1 This is a schematic diagram of the heat exchanger tube end bevel structure in Example 1.

[0058] Figure 2This is a schematic diagram showing the parameter annotations for the heat exchanger tube end bevel structure in Example 1.

[0059] Figure 3 This is a schematic diagram of the heat exchanger tube end bevel structure in Example 2.

[0060] Figure 4 This is a schematic diagram showing the parameter annotations for the heat exchanger tube end bevel structure in Example 2.

[0061] Figure 5 This is a schematic diagram of the simulation calculation model of the heat exchanger tube end bevel structure of Embodiment 1 of this application (number of elements: 20840, number of nodes: 24600).

[0062] Figure 6 and Figure 7 These are schematic diagrams showing the simulation calculation results of the heat exchanger tube end bevel structure of Embodiment 1 of this application.

[0063] Figure 8 This is a schematic diagram of the simulation calculation model of the heat exchanger tube end bevel structure of Embodiment 2 of this application (number of elements: 20840, number of nodes: 24600).

[0064] Figure 9 and Figure 10 This is a schematic diagram of the simulation calculation results of the heat exchanger tube end bevel structure in Embodiment 2 of this application.

[0065] Figure 11 and Figure 12 The failure of heat exchange tubes with I-beveled ends in traditional tubular heat exchanger equipment is due to cracking at the tube ends.

[0066] Figure 13 This is a schematic diagram of the structure of a traditional I-bevel heat exchanger tube end.

[0067] Figure 14 This is a magnified view of a portion of the end of a heat exchanger tube with a traditional I-bevel.

[0068] Figure 15 and Figure 16 This is a magnified view of the welding point and weld site of a traditional I-groove heat exchanger tube end, where B is the weld and C is the heat-affected zone.

[0069] Figure 17 A schematic diagram of the simulation calculation model of the heat exchanger tube end with type I bevel (number of elements: 21160, number of nodes: 24256).

[0070] Figure 18 This is a schematic diagram of the heat source model at the end of the heat exchanger tube with an I-type bevel.

[0071] Figure 19 and Figure 20This is a schematic diagram of the simulation calculation results for the heat exchanger tube end with an I-type bevel, where D is the observation section.

[0072] In the attached diagram: 1-Heat exchange tube; 11-Second bevel; 2-Tube sheet; 21-First bevel; 22-Front end face; 1'-Conventional heat exchange tube; 11'-Type I bevel; 2'-Conventional tube sheet. Detailed Implementation

[0073] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. This application can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application.

[0074] It should be noted that the process equipment or apparatus not specifically mentioned in the following embodiments are all conventional equipment or apparatus in the art.

[0075] Furthermore, it should be understood that the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps, does not preclude the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps, unless otherwise stated. It should also be understood that the combined connection relationship between one or more devices / apparatus mentioned in this application does not preclude the existence of other devices / apparatus before or after the combined devices / apparatus, or the insertion of other devices / apparatus between these explicitly mentioned devices / apparatus, unless otherwise stated. Moreover, unless otherwise stated, the numbering of each method step is merely a convenient tool for identifying each method step, and not for limiting the order of the method steps or limiting the scope of implementation of this application. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of implementation of this application.

[0076] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0077] In the description of this application, it should be understood that the terms "upper," "lower," "left," "right," "inner," "outer," "axial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, features defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0078] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0079] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0080] The present application will be further described below with reference to specific embodiments, but the scope of protection of the present application is not limited thereto.

[0081] like Figures 1-4 As shown, this application provides a heat exchange tube end bevel structure. The tube sheet 2 is provided with a plurality of tube holes for inserting heat exchange tubes 1. A first bevel 21 is provided at the edge of the tube hole. The heat exchange tube 1 is coaxially inserted into the tube hole of the tube sheet 2. The tube end of the heat exchange tube 1 extends outward from the front end face of the tube sheet 2. A second bevel 11 is processed on the inner wall of the tube end of the heat exchange tube 1. The second bevel 11 is an inner V-shaped bevel or an inner arc-shaped bevel, and the root of the second bevel 11 extends beyond the front end face 22 of the tube sheet 2. The heat exchange tube 1 and the tube sheet 2 are welded into a whole.

[0082] like Figures 1-4 As shown, the first bevel 21 is an outward-sloping inward V-shaped bevel.

[0083] like Figures 1-4 As shown, the height of the first bevel is 1–5 mm, preferably 2 mm.

[0084] like Figures 1-4 As shown, the inclination angle of the first bevel is 30° to 60°, preferably 45°.

[0085] like Figures 1-4 As shown, the end of the heat exchange tube 1 extends 3-7 mm beyond the front end face of the tube sheet 2 near the tube end. Preferably, it is 5 mm.

[0086] The inner V-shaped bevel of the heat exchanger tube end bevel structure in this application is as follows: Figure 2 and Figure 3 As shown in the figure, the meanings of each parameter are as follows: OD - outer diameter of heat exchange tube, T - wall thickness of heat exchange tube, L - length of heat exchange tube forming tube sheet, ID - inner diameter of tube sheet, h - height of V-groove in tube sheet, ψ - angle of V-groove in tube sheet, t - height of V-groove in heat exchange tube, θ - angle of V-groove in heat exchange tube.

[0087] like Figure 1 and Figure 2 As shown, the second bevel 11 is an outward-sloping inward V-shaped bevel.

[0088] like Figure 1 and Figure 2 As shown, the height of the second bevel 11 is 1 / 4 to 3 / 4 of the wall thickness of the heat exchange tube 1.

[0089] In some embodiments of this utility model, the wall thickness of the heat exchange tube is 2mm.

[0090] In some embodiments of this invention, the height of the second bevel is 0.5–6 mm, preferably 1 mm.

[0091] In some embodiments of this invention, the inclination angle θ of the second bevel is 30° to 60°, preferably 45°.

[0092] like Figure 1 and Figure 2 As shown, the second bevel 11 is an inner arc-shaped bevel. The concave surface of this inner arc-shaped bevel faces the first bevel.

[0093] like Figure 1 and Figure 2 As shown, the bevel radius of the second bevel 11 is 1 / 2 to 1 / 2 of the wall thickness of the heat exchange tube 1.

[0094] like Figure 1 and Figure 2 As shown, the bevel radius of the second bevel is 2mm.

[0095] This application also provides a heat exchanger, including a heat exchange tube end bevel structure processed according to the calculation model establishment method of the heat exchange tube end bevel, or a heat exchange tube end bevel structure as described in this application.

[0096] This application also provides a method for processing the bevel structure of the heat exchanger tube end, including the step of establishing a calculation model of the bevel structure of the heat exchanger tube end and the step of processing the bevel structure of the heat exchanger tube end based on the calculation model of the bevel structure of the heat exchanger tube end.

[0097] S1 establishes a geometric model of the heat exchanger tube end bevel structure in the modeling software based on the material properties, size parameters and position parameters of the heat exchanger tube and tube sheet. In the geometric model, a first bevel is designed at the edge of the tube hole of the tube sheet and a second bevel is designed on the inner wall of the tube end of the heat exchanger tube.

[0098] S2 divides the geometric model and determines the number of weld passes and layers required for simulating the assembly of tube sheets and heat exchange tubes;

[0099] S3 uses the birth and death element technique to simulate the weld bead surfacing process. The birth and death element subroutine controls the movement of the birth and death elements in conjunction with the heat source to simulate the material accumulation process of the weld bead. The heat source subroutine is compiled and imported into the finite element software to establish a double-ellipsoidal heat source model. This double-ellipsoidal heat source model includes a front semi-ellipsoidal heat source model and a rear semi-ellipsoidal heat source model, wherein:

[0100] The heat flow expression for any point within the front semi-ellipsoidal heat source model is:

[0101] When 0 ≤ z ≤ h:

[0102]

[0103] When h≤z≤H:

[0104]

[0105] The steps for fabricating the heat exchanger tube end bevel structure based on the calculation model of the heat exchanger tube end bevel structure include:

[0106] When 0 ≤ z ≤ h:

[0107]

[0108] When h≤z≤H:

[0109]

[0110] In the formula: q(x,y,z) represents the heat flux distribution of the double ellipsoidal heat source model [J / (m 2 ·s)];Q fHeat (W) is obtained for the first half of the heat source model; h is the inflection point depth (m); H is the heat source depth (m); l is the scaling factor; z is the z-axis coordinate of the double ellipsoidal heat source model (m); a1 is the shape parameter of the first half of the ellipsoid; a2 is the shape parameter of the second half of the ellipsoid; b is the ellipsoid shape parameter.

[0111] S4 loads the double ellipsoidal heat source model onto the geometric model for processing. The heat source subroutine is compiled in the Visual Studio compilation platform using the Fortran language and imported into the Abaqus finite element software. The simulation results of the heat source are obtained based on the Abaqus finite element software. The heat source simulation results include the weld cross-sectional morphology and the temperature field and stress field data of the model changing with time, as well as the stress deformation field.

[0112] S5 corrects the processing parameters of the heat exchanger tube end bevel structure based on the heat source simulation results to ensure that the maximum Mises stress concentration point of the heat exchanger tube is moved to the inside of the heat exchanger tube; the processing parameters include at least the morphology, relative position and bevel parameters of the first bevel on the tube sheet and the second bevel on the heat exchanger tube.

[0113] Based on the processing parameters of the modified heat exchanger tube end bevel structure, S6 processes the first bevel at the edge of the tube hole in the tube sheet and the second bevel on the inner wall of the heat exchanger tube end.

[0114] S7 inserts the heat exchange tube coaxially into the tube hole of the tube sheet, and keeps the root of the second bevel of the heat exchange tube beyond the front end face of the tube sheet. Weld the tube sheet and the heat exchange tube at the first bevel, and connect the front end face of the tube sheet and the tube end of the heat exchange tube through the weld, thus completing the assembly and processing of the bevel structure of the heat exchange tube end.

[0115] Steps S1 to S5 are steps to establish a calculation model for the bevel structure of the heat exchanger tube end; steps S6 to S7 are steps to process the bevel structure of the heat exchanger tube end based on the calculation model.

[0116] In some embodiments of this application, the number of welding layers is 2. The welding current for the first layer is 120A, the welding voltage is 12V, and the welding speed is 160mm / min. The welding current for the second layer is 122A, the welding voltage is 12V, and the welding speed is 120mm / min.

[0117] Example 1

[0118] Taking the inner V-groove at the end of the heat exchanger tube as an example, the heat source subroutine was compiled in the Visual Studio compilation platform using the Fortran language and imported into the Abaqus finite element software to simulate the stress distribution of the welded joint.

[0119] Specifically, the parameters of the tube sheet and heat exchanger tubes in this embodiment with the tube end bevel structure are as follows: Heat exchanger tube material grade GB / T 13296S31603, specification φ25*2mm. Tube sheet material grade S31603Ⅲ, thickness 85mm, inner diameter φ25.3mm, tube extension length beyond the outer surface of the tube sheet 5mm. The parameters of the heat exchanger tube end bevel structure in this embodiment are as follows: OD=25mm, T=2mm, L=5mm, ID=25.3mm, h=2mm, ψ=45°, t=1mm, θ=45°. The calculation is performed for the inner V-shaped bevel at the tube end; the second bevel diagram of the heat exchanger tube end is shown below. Figure 1 and Figure 2 The settlement results are shown below. Figure 6 and Figure 7 .

[0120] Filler wire welding was achieved using the birth-death element technique. Specifically, the application of a moving heat source was implemented: first layer welding current: 120A, welding voltage: 12V, welding speed: 160mm / min; second layer welding current: 122A, welding voltage: 12V, welding speed: 120mm / min. Simulation parameters are shown in Table 1, and the simulation calculation model is shown in [Table 1]. Figure 5 The simulation results are shown below. Figure 6 and Figure 7 .

[0121] Table 1 Simulation parameters for filler wire welding using the birth-death element technique.

[0122]

[0123] Based on the above calculations, the maximum Mises stress at the inner V-groove of the pipe end is 331 MPa, and it is distributed inside the pipe.

[0124] Example 2

[0125] For the inner arc-shaped bevel of the heat exchanger tube end bevel structure, the heat source subroutine was compiled in the Visual Studio compilation platform using the Fortran language and imported into the Abaqus finite element software to simulate the stress distribution of the welded joint.

[0126] like Figure 3 and Figure 4 As shown, taking the inner circular bevel at the tube end as an example, the meanings of each parameter in the figure are as follows: OD - outer diameter of heat exchange tube, T - wall thickness of heat exchange tube, L - length of heat exchange tube forming tube sheet, ID - inner diameter of tube sheet, h - height of V-shaped bevel in inner tube sheet, ψ - angle of V-shaped bevel in inner tube sheet, R - radius of inner circular bevel of heat exchange tube.

[0127] Specifically, taking the inner circular bevel at the tube end as an example, the parameters of the tube sheet and heat exchanger tubes in this embodiment are as follows: Heat exchanger tube material grade GB / T 13296S31603, specification φ25*2mm. Tube sheet material grade S31603Ⅲ, thickness 85mm, inner diameter φ25.3mm, tube extending 5mm beyond the outer surface of the tube sheet. The parameters of the heat exchanger tube end bevel structure in this application are as follows: OD=25mm, T=2mm, L=5mm, ID=25.3mm, h=2mm, ψ=45°, R=2mm. The inner bevel at the tube end is calculated, and the second bevel diagram of the heat exchanger tube end is shown below. Figure 3 and Figure 4 See the simulation calculation model. Figure 8 The settlement results are shown below. Figure 9 and Figure 10 .

[0128] Filler wire welding is achieved using the birth and death unit technology, with specific parameters the same as in Example 1.

[0129] Based on the above calculations, the maximum Mises stress at the inner circular bevel of the pipe end is 319 MPa, and it is distributed inside the pipe.

[0130] Comparative Example 1 uses a traditional heat exchanger tube with an "I"-shaped bevel as an example for illustration. The heat source subroutine is compiled using Fortran within the Visual Studio compilation platform and imported into the Abaqus finite element software to simulate the stress distribution of the welded joint.

[0131] Specifically, the parameters of the tube sheet and heat exchanger tubes in this embodiment with the tube end bevel structure are as follows: The heat exchanger tube material grade is GB / T 13296S31603, with a specification of φ25*2mm. The tube sheet material grade is S31603Ⅲ, with a thickness of 85mm, an inner diameter of φ25.3mm, and a tube extension length of 5mm beyond the outer surface of the tube sheet. The parameters of the heat exchanger tube end bevel structure in this application are as follows: OD = 25mm, T = 2mm, L = 5mm, ID = 25.3mm, h = 2mm, ψ = 45°. Calculations are performed, and the conventional I-type bevel diagram for heat exchanger tube ends is shown below. Figures 13-16 See the simulation calculation model. Figure 17 The settlement results are shown below. Figures 19-20 A schematic diagram of the failure of the heat exchanger tubes with I-bevel joints in an actual tubular heat exchanger is shown below. Figure 11 and Figure 12 As shown.

[0132] Filler wire welding is achieved using the birth and death unit technology, with specific parameters the same as in Example 1.

[0133] Based on the above calculations, the maximum Mises stress of the Type I bevel is 392 MPa, and it is distributed on the inner wall of the very end of the pipe, making the pipe end extremely prone to cracking. Furthermore, the Type I bevel is easily scraped against the positioning mandrel of the welding torch, leading to pipe end contamination.

[0134] The test results from Examples 1, 2 and Comparative Example 1 show that the improved heat exchange tube end bevel structure changes the welding stress distribution by altering the tube end morphology; and it also prevents tube end contamination and cracking by changing the tube end morphology.

[0135] The above embodiments are for illustrating the implementation schemes disclosed in this application and should not be construed as limiting this application. Furthermore, various modifications listed herein, as well as variations in methods and compositions of the utility model, will be apparent to those skilled in the art without departing from the scope and spirit of this application. Although this application has been specifically described in conjunction with various specific preferred embodiments, it should be understood that this application should not be limited to these specific embodiments. In fact, various modifications as described above that are obvious to those skilled in the art to obtain the utility model should be included within the scope of this application.

Claims

1. A heat exchange tube end bevel structure, comprising a heat exchange tube (1) and a tube sheet (2), characterized in that, The tube sheet (2) is provided with a plurality of tube holes for inserting heat exchange tubes (1), and the front end face of the tube hole is provided with a first bevel (21); the heat exchange tube (1) is coaxially inserted into the tube hole of the tube sheet (2), the tube end of the heat exchange tube (1) extends outward from the front end face of the tube sheet (2), the inner wall of the tube end of the heat exchange tube (1) is processed with a second bevel (11), the second bevel (11) is an inner V-shaped bevel or an inner arc bevel, and the root of the second bevel (11) extends beyond the front end face (22) of the tube sheet (2); the heat exchange tube (1) and the tube sheet (2) are welded into a whole.

2. The heat exchanger tube end bevel structure according to claim 1, characterized in that: The first bevel (21) is an outward-sloping inward V-shaped bevel.

3. The heat exchanger tube end bevel structure according to claim 2, characterized in that: The height of the first bevel (21) is 1 to 5 mm; the inclination angle θ of the first bevel (21) is 30° to 60°.

4. The heat exchanger tube end bevel structure according to claim 1, characterized in that: The second bevel (11) is an outward-sloping inward V-shaped bevel.

5. The heat exchanger tube end bevel structure according to claim 4, characterized in that: The height of the second bevel (11) is 1 / 4 to 3 / 4 of the wall thickness of the heat exchange tube (1).

6. The heat exchanger tube end bevel structure according to claim 4, characterized in that: The inclination angle θ of the second bevel (11) is 30° to 60°.

7. The heat exchanger tube end bevel structure according to claim 1, characterized in that: The second bevel (11) is an inner arc bevel, and the inner arc bevel is concave to the first bevel.

8. The heat exchanger tube end bevel structure according to claim 7, characterized in that: The bevel radius of the second bevel (11) is 1 / 2 to 1 / 2 of the wall thickness of the heat exchange tube (1).

9. The heat exchanger tube end bevel structure according to claim 1, characterized in that: The end of the heat exchange tube (1) extends 3 to 7 mm from the front end face (22) of the tube sheet (2) near the end of the tube.

10. A heat exchanger, characterized in that: Includes the heat exchange tube end bevel structure as described in any one of claims 1 to 8.

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