Shell and tube heat exchanger with nichrome medium tube stack and production process of shell and tube heat exchanger

Abstract

The invention provides a shell and tube heat exchanger with a nichrome medium tube set and a production process of the shell and tube heat exchanger. The shell and tube heat exchanger comprises baffle plates. The medium pipe group penetrates through the baffle plate through holes and is used for carrying out energy exchange; the medium pipe group is in clearance fit with the baffle plate and is connected with the baffle plate in a welding manner through brazing filler metal; the flow collecting cover is communicated with the medium pipe group; the tube plate is welded with the flow collecting cover; the medium pipe set is matched with the pipe plate, welded and connected with the pipe plate, and the medium pipe set is made of nickel-chromium alloy materials. The heat exchanger welded through the welding process that the brazing furnace is adopted for integrated welding is safe and reliable, the labor intensity of workers can be relieved, operation is easy, professionals are not needed, then the labor cost is reduced, the working efficiency is greatly improved, and meanwhile the production cost is reduced by reducing the welding types.

Description

Technical Field

[0001] The present invention belongs to the technical field of heat exchanger preparation, and particularly relates to a shell-and-tube heat exchanger with a nickel-chromium alloy medium tube group and its production process. Background Art

[0002] A heat exchanger includes a tube sheet, a tube group, a shell, a baffle plate, an inlet liquid cover, and an outlet liquid cover. The tube group includes short connecting tubes, straight tubes, and U-shaped joints. When assembled in the traditional way, single welding is required for each part of the heat exchanger to form multiple working steps, and then the working steps are assembled and connected by methods such as flame brazing or expansion jointing.

[0003] When using flame brazing for welding, first, the tube sheet and the short connecting tube are welded by flame brazing. After completing the welding of this working step, it is then welded to the straight tube and the U-shaped joint. Then, the baffle plate is installed on the straight tube to form an integral body, and finally, the integral body is installed into the shell to complete the assembly of the heat exchanger.

[0004] However, during welding, the heat exchanger cannot be welded integrally, which leads to the need for multi-point welding during welding, resulting in difficulties, long processing time, and easy leakage.

[0005] If expansion jointing is used, the protrusions on the pipe wall are matched with the grooves of the expansion joint by physical expansion to make them tightly connected together. During the heat exchange process of the heat exchanger, the material is easily affected by thermal expansion and contraction, and there is a risk of leakage at the expansion joint.

[0006] Traditional medium tubes are made of copper tubes, and the trace elements contained in the aqueous medium used inside the copper tubes will cause corrosion of the copper tubes, and a large amount of water scale is easily generated on the outer wall. The medium used during the removal of the water scale will cause secondary corrosion of the copper tubes. If simply replaced with a stainless steel pipeline, the basic heat exchange performance requirements cannot be met, and because stainless steel has poor plasticity, it is not easy to produce using traditional processing techniques.

[0007] In view of this, how to solve the defects existing in the above technical solutions, that is, to ensure the heat exchange performance of the heat exchanger, extend the service life of the heat exchanger, and reduce the maintenance risk, it is necessary to develop a shell-and-tube heat exchanger with a nickel-chromium alloy medium tube and its production process. Summary of the Invention

[0008] In view of the problems existing in the background art, on the one hand, the present invention provides a shell-and-tube heat exchanger with a nickel-chromium alloy medium tube group, including internal components welded by a welding process using a brazing furnace for integral welding, including:

[0009] A baffle plate;

[0010] A medium tube group passing through the through holes of the baffle plate and used for energy exchange;

[0011] The medium tube group is in clearance fit with the baffle plate and is connected by soldering with solder;

[0012] A header connected to the medium tube group;

[0013] A tube sheet welded to the header;

[0014] The medium tube group is fitted with the tube sheet and connected by welding,

[0015] The medium tube group is made of nickel-chromium alloy.

[0016] Optionally, it further includes a housing, and the internal components are arranged inside the housing;

[0017] The housing includes multiple groups of housing plates;

[0018] The medium tube group is arranged inside the housing,

[0019] The medium tube group is assembled with the housing through the baffle plate.

[0020] Optionally, the header includes a first header, an intermediate header, and a second header,

[0021] The medium tube group includes multiple groups of medium tubes,

[0022] The second header is provided with a second medium port,

[0023] The second header is connected to the intermediate header through one group of the medium tubes of the medium tube group,

[0024] and is connected to another group of the medium tubes of the medium tube group through the intermediate header,

[0025] and another group of the medium tubes of the medium tube group is connected to the first header,

[0026] The first header further includes a first medium port.

[0027] Optionally, the welding connection method adopted by the tube sheet and the header is insertion lap welding connection;

[0028] The housing, baffle plate, header, medium tube group, and tube sheet of the heat exchanger formed by integrally welding through a brazing furnace are all made of metal.

[0029] A welding process for a shell-and-tube heat exchanger with a nickel-chromium alloy medium tube group includes the following steps:

[0030] S1, Prepare each component of the heat exchanger and conduct inspections,

[0031] The components include a first header, an intermediate header, a second header, a housing, and a baffle plate;

[0032] S2, Assembly 1, complete the assembly of the internal components;

[0033] S3, Assembly 2, complete the overall assembly;

[0034] S4, Place the assembled heat exchanger as a whole into a brazing furnace for one-time welding.

[0035] Optionally, step S2 further includes the following steps:

[0036] S2.1, Place the tube sheet and the baffle plate on the assembly tooling simultaneously;

[0037] S2.2, Assembly between the medium tube group and the baffle plate, including:

[0038] Pass the medium tube group through the through holes of the baffle plate so that the medium tube group and the baffle plate are matched,

[0039] There is a gap between the medium tube group and the baffle plate, and the gap is filled with brazing filler metal;

[0040] S2.3, Assembly between the medium tube group and the tube sheet, including:

[0041] The medium tube group and the baffle plate are matched;

[0042] Place the medium tube solder on the outer diameter of the medium tube group,

[0043] Insert the medium tube group with the medium tube solder into the sunken material placement groove provided on the tube sheet.

[0044] Optionally, step S3 further includes assembling the housing by multiple groups of shell plates, placing the internal components in step S2 into the housing,

[0045] Assemble the housing on the tube sheet of the internal components;

[0046] Assemble the header and the tube sheet.

[0047] Optionally, insert and lap the first header, the intermediate header, and the second header with the tube sheet;

[0048] Fill the solder in the sunken groove, and the sunken groove is opened at the position where the header is connected to the tube sheet.

[0049] Optionally, step S3 further includes the following steps,

[0050] S3-1, Assembly between the shell plate and the baffle plate, including:

[0051] Place the solder on the contact points of the shell plates to form a first solder filling layer;

[0052] Assemble the shell plates onto the internal components in step S2 respectively, and make the vertical surface of the baffle plate and the end surface of the shell plate closely adhere through the first solder filling layer;

[0053] S3-2. The assembly between the tube sheet and the shell includes:

[0054] By setting a second welding layer at the connection position of adjacent two groups of the shell plates,

[0055] Fix the position by spot welding the second welding layer to realize the connection between adjacent shell plates and form a shell;

[0056] First welding layers are provided at the connection positions of the tube sheet and the shell plates, so that the tube sheet and the shell are closely adhered;

[0057] S3-3. Assemble the tube sheet and the manifold

[0058] In summary, the beneficial effects of the present invention are:

[0059] 1. The heat exchanger of the present invention with a nickel-chromium alloy material medium tube group can achieve the heat transfer performance required by the standard, greatly extend the overall service life, and reduce the leakage risk that may occur during later cleaning and maintenance.

[0060] 2. The present invention enables the product to be safe and reliable through multi-component integrated welding, can reduce the labor intensity of workers, is simple to operate, does not require professionals, thereby reducing the labor cost, and greatly improves the work efficiency. At the same time, by reducing the types of welding (such as argon welding, flame soldering, etc.), the production cost is reduced.

[0061] 3. The present invention replaces the U-shaped joint of the traditional extended pipeline by adding an intermediate manifold, which is simple to install. When performing integrated welding in a brazing furnace, all welding points are concentrated on the tube sheet, reducing the number of welding points, and thus greatly reducing the probability of leakage points.

[0062] 4. The present invention adopts overall out-of-furnace assembly. During the assembly process, a brazing flux is filled in the welding parts, and the connection method of spot welding or gap control is carried out between the workpieces during the assembly process, reducing the working hours consumed by welding and the processing cost brought by welding. After the assembly is completed, high-temperature solder is melted in the furnace, and the solder slowly fills the gap by capillary action to realize the connection between components, meet the welding requirements, and satisfy the product design requirements. Description of the Drawings

[0063] Figure 1Schematic diagram of the overall structure of an embodiment of a shell-and-tube heat exchanger with a nickel-chromium alloy medium tube group according to the present invention;

[0064] Figure 2 Schematic diagram of the structure of the sealed tube part of an embodiment of a shell-and-tube heat exchanger with a nickel-chromium alloy medium tube group according to the present invention;

[0065] Figure 3 For the present invention Figure 2 Enlarged view of the structure of the medium tube group in the present invention;

[0066] Figure 4 Enlarged view of the baffle plate structure of an embodiment of a shell-and-tube heat exchanger with a nickel-chromium alloy medium tube group according to the present invention;

[0067] Figure 5 Two-dimensional view of the partial structure of an embodiment of a shell-and-tube heat exchanger with a nickel-chromium alloy medium tube group according to the present invention;

[0068] Figure 6 Enlarged view of the structure at the connection position between the tube sheet and the medium tube group of an embodiment of a shell-and-tube heat exchanger with a nickel-chromium alloy medium tube group according to the present invention;

[0069] Figure 7 For the present invention Figure 5 Enlarged view of the partial structure in the present invention;

[0070] Figure 8 Enlarged view of the structure at the second medium port position of the collector hood of an embodiment of a shell-and-tube heat exchanger with a nickel-chromium alloy medium tube group according to the present invention;

[0071] Figure 9 Enlarged view of the structure at the position of the intermediate collector hood of a shell-and-tube heat exchanger with a nickel-chromium alloy medium tube group according to the present invention;

[0072] Figure 10 Schematic diagram of the overall structure of a conventional heat exchanger.

[0073] Reference numerals:

[0074] 100, heat exchanger;

[0075] 10, housing; 101, first welding layer; 102, shell plate;

[0076] 20, collector hood; 201, first collector hood; 202, intermediate collector hood; 203, second collector hood; 204, second medium port

[0077] 30, baffle plate; 301, baffle plate vertical surface; 303, through hole;

[0078] 40, medium tube group;

[0079] 4011, medium tube solder;

[0080] 50. Tube sheet; 501. Sinking groove; 502. Filler layer A of solder; 503. Sinking type discharging groove; 504. Channel;

[0081] 60. First filler layer of solder;

[0082] 70. Second welding layer;

[0083] 80. Second filler layer of solder. Detailed implementation manners

[0084] This application document is mainly used for the heat exchange of fluid media.

[0085] In traditional medium pipes, copper pipes are used. However, trace elements contained in the aqueous medium used inside the copper pipes can cause corrosion of the copper pipes, and a large amount of water scale is likely to be generated on the outer wall. The medium used in the process of removing the water scale will cause secondary corrosion to the copper pipes. If simply replaced with stainless steel pipelines, the basic heat exchange performance requirements cannot be met, and because stainless steel has poor plasticity, it is not easy to be produced by traditional processing techniques. In order to meet the heat exchange performance requirements of the heat exchanger per unit volume, it is necessary to increase the actual heat exchange area of the medium pipe group inside the heat exchanger. By reducing the diameter of the medium pipe and increasing the number of medium pipes, the traditional expansion joint process is difficult to apply. To solve the above technical problems, as Figure 1-10 shown, this embodiment provides a shell-and-tube heat exchanger 100 with a nickel-chromium alloy medium pipe group, including internal components welded by a welding process using a brazing furnace for integral welding, including a baffle plate 30.

[0086] Further, the heat exchanger 100 includes a housing 10 assembled by multiple groups of shell plates 102,

[0087] and a medium pipe group 40 disposed inside the housing 10 for energy exchange,

[0088] a baffle plate 30 for the medium pipe group 40 to pass through is disposed inside the housing 10, and it is assembled with the housing 10 through the baffle plate 30. The baffle plate 30 is located inside the housing 10 and can enable the medium to flow at a predetermined flow rate and in a predetermined direction.

[0089] a header 20 communicated with the medium pipe group 40, and the header 20 is assembled with the housing 10 through a tube sheet 50. The header 20 is welded to the tube sheet 50; the medium pipe group 40 is matched with the tube sheet 50 and is welded and connected;

[0090] The medium pipe group 40 is made of nickel-chromium alloy material. The nickel-chromium alloy material is preferably martensitic, austenitic, ferritic and duplex stainless steel, and more preferably 303, 304, 316, 317 austenitic stainless steel.

[0091] The medium tube group adopts at least one group of medium tubes;

[0092] The housing 10, the baffle 30, the current collector cover 20, the medium tube group 40 and the tube sheet 50 are integrally welded through a brazing furnace to form the overall heat exchanger 100.

[0093] Furthermore, the brazing furnace can be a vacuum furnace, a continuous tunnel furnace or other welding furnaces that can implement the one-piece welding solution of this application.

[0094] Furthermore, the housing 10, the baffle 30, the current collector cover 20 and the tube sheet 50 of the heat exchanger 100 are made of stainless steel, and can also be made of metals such as carbon steel, copper or aluminum.

[0095] Furthermore, the baffle 30 includes the baffle vertical surface 301, and the baffle vertical surface 301 is closely attached to the inner wall of the shell plate 102 of the housing 10.

[0096] In this embodiment, the heat exchanger with a medium tube group made of nickel-chromium alloy material can achieve the heat transfer performance required by the standard, greatly extend the overall service life, reduce the leakage risk that may occur during later cleaning and maintenance, and is welded by the welding process of one-piece welding through a brazing furnace, making the product safe and reliable, reducing the labor intensity of workers, being simple to operate, not requiring professional personnel, thus reducing the labor cost, greatly improving the work efficiency, and at the same time reducing the types of welding (such as argon welding, flame brazing, etc.), thereby reducing the production cost.

[0097] The traditional heat exchanger tube group includes short connecting tubes, straight tubes and U-shaped joints. During assembly, the U-shaped joints need to be inserted into the tube sheet for mechanical expansion or connected by flame brazing. Moreover, due to reducing the diameter of the medium tubes and increasing the number of medium tubes, it is impossible to use expansion joints. If flame brazing is used for connection, since most of the internal structure of the heat exchanger is a U-shaped circuit, it is necessary to use U-shaped joints to perform multi-point welding with short tubes and straight tubes. When welding, it is necessary to weld row by row from high to low. When the first row of welding is completed and the second row of welding is carried out, the residual temperature of the flame will be generated. Due to the large density of the tube pitch, the residual temperature will affect the welding of the first row, forming leakage points. Therefore, professional workers with extremely strong professional capabilities are required for professional welding, and the production cost is extremely high, and even so, it is still impossible to completely avoid the appearance of leakage points. For this reason, the present invention solves the above technical problems, please refer to Figure 1-10 as shown

[0098] The flow hood 20 includes a first flow hood 201, an intermediate flow hood 202 and a second flow hood 203. The medium tube group 40 includes at least one group of medium tubes. The diameter of a single medium tube in the medium tube group 40 is 3 - 7 mm, and preferably 5 mm. When the diameter is 5 mm, the heat exchange performance of the heat exchanger is 11 - 12 Kw per square meter.

[0099] The second flow hood 203 is provided with a second medium port 204. The second flow hood 203 is connected to the intermediate flow hood 202 through one group of the medium tubes in the medium tube group 40, and is connected to the other group of the medium tubes in the medium tube group 40 through the intermediate flow hood 202. The other group of the medium tubes in the medium tube group is connected to the first flow hood 201.

[0100] Further, the first flow hood 201 further includes a first medium port.

[0101] In this embodiment, those skilled in the art should be able to understand that for a traditional heat exchanger as Figure 10 shown, when connecting the U-shaped joint in the extended path pipeline, multiple spot welds are required, which results in multiple weld points at the tube sheet and the U-shaped joint. The installation is relatively cumbersome and requires staff with extremely strong professional capabilities for professional welding, resulting in extremely high production costs. Moreover, even so, it is still impossible to completely avoid the occurrence of leakage points. Therefore, in the present invention, by adding an intermediate flow hood 202, the U-shaped joint in the traditional extended path pipeline is replaced. The installation is simple. When performing integral welding in a brazing furnace, all the weld points are concentrated on the tube sheet, reducing the number of weld points, and thus greatly reducing the probability of leakage points.

[0102] Further, the shell plate 102 is arranged in a quadrilateral shape with a middle bulge. The shell formed by combining multiple groups of shell plates arranged in a quadrilateral shape with a middle bulge has higher pressure-bearing capacity.

[0103] A welding process for a shell-and-tube heat exchanger with a nickel-chromium alloy medium tube group includes the following steps:

[0104] Step S1: Prepare each component of the heat exchanger and conduct inspections.

[0105] Among them, the components include a first flow hood, an intermediate flow hood, a second flow hood, a shell and a baffle.

[0106] Step S2: Assembly 1, complete the assembly of internal components.

[0107] Step S3: Assembly 2, complete the overall assembly.

[0108] Step S4: Put the assembled heat exchanger as a whole into a brazing furnace for one-time welding.

[0109] Further, in practical applications, it can be determined whether to clean each component before completing step S2 according to the actual application situation. If cleaning is carried out, the following steps are further included:

[0110] (1) Preliminary rinsing, preliminarily cleaning each component with pure water to remove obvious dust and particulate matter on the surface of the component;

[0111] (2) Oil stain cleaning, soaking each component in hot water containing a cleaning agent and using an ultrasonic cleaner to remove the oil stains on each component;

[0112] (3) Drying, drying naturally or blowing dry.

[0113] Further, step S2 further includes the following steps:

[0114] S2.1. Place the tube sheet and the baffle plate on the assembly tooling simultaneously;

[0115] S2.2. Assembly between the medium tube group and the baffle plate, including:

[0116] Pass the medium tubes of the medium tube group 40 through the through holes of the baffle plate, so that the medium tubes of the medium tube group 40 and the baffle plate are in clearance fit,

[0117] where there is a gap of 0.1 - 0.2 mm between the medium tubes of the medium tube group 40 and the baffle plate, and the gap is filled with brazing filler metal; by filling the brazing filler metal in the gap, when it is placed in a brazing furnace for welding, the filled brazing filler metal in the gap slowly capillary-fills the gap, making the medium tubes of the medium tube group 40 and the baffle plate form a sealed connection, preventing the external circulation medium from flowing out through the gap between the straight tube and the through hole of the baffle plate, enabling the external circulation medium to flow completely along the specified route, and reducing pressure loss and energy exchange difference;

[0118] S2.3. Complete the assembly between the medium tube group and the tube sheet to form an internal component, and the medium tubes of the medium tube group 40 are matched with the tube sheet;

[0119] Place the medium tube solder 4011 on the outer diameter of the medium tubes of the medium tube group 40, and insert the medium tubes of the medium tube group 40 with the medium tube solder 4011 into the sunken material placement groove 504 provided on the tube sheet 50;

[0120] By opening the sunken material placement groove 504 on the tube sheet 50, it is convenient to fix the solder, so that the medium tubes of the medium tube group and the sunken material placement groove are in a tightly attached state, and at the same time, when in the welding state, it can ensure that the molten solder flows along the specified route and does not flow turbulently.

[0121] Further, in actual application, the depth of the sunken material discharge groove 504 can be set according to the value of the solder in the dielectric tube 4011. For example:

[0122] If the inner diameter of the solder is 4.9 mm * wire diameter 0.8 mm, then the depth of the sunken material discharge groove 504 is: 2 mm.

[0123] In this embodiment, those skilled in the art should be able to understand that when in the welding state, since all the solder will soften and expand during the heating process, and then the shape of the solder changes. Due to the small distance and large density between adjacent dielectric tube groups, the solder easily flows onto adjacent dielectric tube groups. As a result, there is less solder on this dielectric tube group, causing leakage. To solve the above technical problems, the present invention opens a sunken material discharge groove 504 on the tube sheet 50 to facilitate fixing the solder, so that a tight connection state is presented between the dielectric tube group and the sunken material discharge groove. And at the same time, when in the welding state, it can ensure that the molten solder flows along the specified route without turbulent flow.

[0124] Further, multiple groups of grooves are also provided on the dielectric tubes of the dielectric tube group at the position of the sunken material discharge groove 504 on the tube sheet 50 in step S2, and the grooves continuously extend along the longitudinal direction of the straight tube. By opening the grooves, it is convenient for the molten solder to be guided during the welding state.

[0125] Step S3 further includes the following steps

[0126] Step S3.1, the housing 10 is prefabricated by assembling multiple groups of shell plates 102, and the internal components in step S2 are placed in the housing 10.

[0127] Step S3.2, the housing 10 is assembled on the tube sheet 50 of the internal components;

[0128] Step S3.3, the manifold and the tube sheet 50 are assembled.

[0129] Further, the specific assembly between the manifold and the tube sheet specifically further includes the following steps

[0130] The manifold (the first manifold, the intermediate manifold and the second manifold) is inserted and overlapped with the tube sheet 50;

[0131] By filling solder in the sinking groove, the sinking groove is opened at the connection position between the manifold (the first manifold, the intermediate manifold and the second manifold) and the tube sheet 50.

[0132] In this embodiment, the present invention adopts overall off-furnace assembly. During the assembly process, brazing flux is filled (filled or adhered) at the welding parts, and spot welding or gap control connection methods are used between workpieces during the assembly process (no welding operation is performed during assembly), reducing the working hours consumed by welding and lowering the processing cost brought by welding. After the assembly is completed, high-temperature brazing filler metal is melted in the furnace, and the brazing filler metal slowly fills the gap by capillary action (moistening the weld bead) to achieve the connection between components, meeting the welding requirements and satisfying the product design needs.

[0133] Furthermore, the brazing furnace can be selected according to actual needs, and it can be a vacuum furnace, a tunnel furnace, or other equipment that can achieve the welding method of the present application. For example, when used in a vacuum furnace,

[0134] (1) Put the assembled exchanger to be welded as a whole into the vacuum furnace; heat the vacuum furnace to 420°C - 470°C, hold for 20 - 32 minutes, and apply a vacuum pressure of 1.5 - 2.0 Ebar to make the workpieces evenly heated; avoid insufficient heat inside the stacked workpieces.

[0135] (2) Heat the vacuum furnace to 860°C - 920°C, hold for 20 - 45 minutes, and apply a vacuum pressure of 1.5 - 2.0 Ebar to make the workpieces evenly heated; avoid insufficient heat inside the stacked workpieces.

[0136] (3) Heat the vacuum furnace to 1000°C - 1350°C, hold for 20 - 35 minutes, and apply a vacuum pressure of 1.5 - 2.0 Ebar to make the workpieces and welding materials evenly heated; avoid insufficient heat inside the stacked workpieces and uneven temperature of the welding materials.

[0137] (4) Heat the vacuum furnace to 1000°C - 1500°C, preferably 1135 degrees, hold for 25 - 55 minutes, and apply a vacuum pressure of 1.5 - 2.0 Ebar to make the welding materials liquefy and perform capillary action in the weld to fill the weld with brazing filler metal; avoid welding defects of workpieces caused by insufficient time and temperature.

[0138] (5) After the workpieces complete the above heating and heat preservation stages, cool down. When the temperature drops below 50 degrees, the vacuum furnace is depressurized, and the integrally welded exchanger is taken out.

[0139] If used in a tunnel furnace, heat the first zone of the tunnel furnace to 980 - 1085°C and set a gas flow rate of 1 - 2.5 L / min;

[0140] Heat the second zone of the tunnel furnace to 1020 - 1120°C and set a gas flow rate of 2 - 4 L / min;

[0141] The three zones of the tunnel furnace are heated to 1020 - 1120 °C, and a gas flow rate of 2 - 4 L / min is set;

[0142] The four zones of the tunnel furnace are heated to 1020 - 1120 °C, and a gas flow rate of 2 - 3 L / min is set.

[0143] After the welding is completed, the exchanger with integrated welding is taken out. Among them, the speed of the tunnel furnace mesh belt is 160 - 200 mm / min; the cooling water pressure is 0.05 - 0.15 MPa.

[0144] Example Two

[0145] In actual application, the components are integrally installed in the pre - assembled shell. However, when using the above - mentioned assembly method, an assembly gap needs to be reserved. If the assembly gap is small, there will be difficulties in assembly. While a larger assembly gap is convenient for assembly, the fluid will flow out through the gap, and the outflowing fluid beam will cause the gas - liquid medium to form turbulence, hindering the convection and conduction of heat and reducing the heat exchange efficiency. To solve the above - mentioned technical problems, this application improves step S3. Please refer to Figure 1-10 as shown in

[0146] A welding process for a shell - and - tube heat exchanger with a nickel - chromium alloy medium tube group includes the following steps:

[0147] Step S1: Prepare each component of the heat exchanger and conduct inspections.

[0148] Among them, the components include the first header, the middle header, the second header, the shell, and the baffle plate;

[0149] Step S2: Assembly One, complete the assembly of the internal components;

[0150] Step S3: Assembly Two, complete the overall assembly;

[0151] Step S4: Put the assembled heat exchanger as a whole into the brazing furnace for one - time welding.

[0152] Furthermore, in actual application, it can be judged according to the actual application situation whether to clean each component before completing step S2. If cleaning is carried out, the following steps are also included:

[0153] (1) Preliminary rinsing, preliminarily clean each component with pure water to remove obvious dust and particulate matter on the surface of the components;

[0154] (2) Oil stain cleaning, soak each component in hot water containing a cleaning agent, and use an ultrasonic cleaning machine to remove the oil stains on each component;

[0155] (3) Drying, air - dry it naturally or by blowing.

[0156] Further, step S2 further includes the following steps:

[0157] S2.1. Place the tube sheet and the baffle plate on the assembly tooling simultaneously;

[0158] S2.2. Assembly between the medium tube group and the baffle plate, including:

[0159] Pass the medium tube group 40 through the through holes of the baffle plate, so that the medium tube group 40 and the baffle plate are in clearance fit,

[0160] where there is a clearance of 0.1 - 0.2 mm between the medium tubes of the medium tube group 40 and the baffle plate, and the clearance is filled with brazing filler metal; by filling the brazing filler metal in the clearance, when it is placed in the brazing furnace for welding, the filled brazing filler metal in the clearance slowly fills the clearance by capillary action, so that the medium tubes of the medium tube group 40 and the baffle plate form a sealed connection, preventing the external circulation medium from flowing out of the clearance between the straight tube and the through holes of the baffle plate, making the external circulation medium flow completely along the specified route, reducing pressure loss and energy exchange difference;

[0161] S2.3. Complete the assembly between the medium tube group and the tube sheet to form an internal component, and the medium tubes of the medium tube group 40 cooperate with the tube sheet 50;

[0162] Place the medium tube solder 4011 on the outer diameter of the medium tubes of the medium tube group 40, and insert the medium tubes of the medium tube group 40 with the medium tube solder 4011 into the sunken feeding groove 504 provided on the tube sheet 50;

[0163] By providing the sunken feeding groove 504 on the tube sheet 50, it is convenient to fix the solder, so that the medium tube group and the sunken feeding groove are in close contact with each other, and at the same time when in the welding state, it can ensure that the molten solder flows along the specified route without turbulent flow.

[0164] Further, in actual application, the depth of the sunken feeding groove 504 can be set according to the value of the medium tube solder 4011, for example:

[0165] If the inner diameter of the solder is 4.9 mm * wire diameter 0.8 mm, then the depth of the sunken feeding groove 504 is: 2 mm.

[0166] In this embodiment, those skilled in the art should be able to understand that when in the welding state, since all solders will soften and expand during heating, the solder morphology will change. Due to the small distance and large density between adjacent dielectric tube groups, the solder easily flows onto adjacent dielectric tube groups. As a result, there is less solder on this dielectric tube group, causing leakage. To solve the above technical problems, the present invention provides a sunken material placement groove 504 on the tube sheet 50 to facilitate fixing the solder, so that a tight connection state is presented between the dielectric tube group and the sunken material placement groove. At the same time, when in the welding state, it can ensure that the liquid solder flows along a specified route without turbulent flow.

[0167] Further, multiple groups of grooves are also provided on the dielectric tubes of the dielectric tube group at the position of the sunken material placement groove 504 on the tube sheet 50, and the grooves continuously extend along the longitudinal direction of the straight tube. By providing the grooves, it is convenient for the liquid solder to be guided during the welding state.

[0168] Step S3 further includes the following steps

[0169] S3-1, The assembly between the shell plate 102 and the baffle plate 30 includes:

[0170] Place the brazing filler metal at the contact points of the shell plate 102 to form a first brazing filler metal filling layer 60.

[0171] Assemble the shell plate 102 on the internal components in step S2 respectively. Through the first brazing filler metal filling layer 60, the baffle plate vertical surface 301 and the end surface of the shell plate 102 are closely attached.

[0172] S3-2, The assembly between the tube sheet 50 and the shell 10 includes:

[0173] By providing a second welding layer 70 at the connection position between two adjacent shell plates 102.

[0174] Fix the position by spot welding the second welding layer 70 to realize the connection between adjacent shell plates 102 and form the shell 10.

[0175] First welding layers 101 (welding points between the tube sheet and the shell) are provided at the connection positions between the tube sheet 50 and the shell plate 102, so that the tube sheet 50 and the shell 10 are closely attached.

[0176] S3-3, Assemble the tube sheet 50 and the manifold 20.

[0177] Further, the specific assembly between the manifold 20 and the tube sheet 50 further includes the following steps

[0178] Insert and lap joint the current collector cover 20 (the first current collector cover, the intermediate current collector cover, and the second current collector cover) with the tube sheet 50.

[0179] Fill the sinking groove with solder, where the sinking groove is opened at the connection position between the current collector cover (the first current collector cover, the intermediate current collector cover, and the second current collector cover) and the tube sheet 50.

[0180] In this embodiment, the present invention assembles multiple groups of shell plates on the baffle plates of the internal components completed in step S3, making the baffle plates 30 and the shell plates closely adhere to each other without leaving a gap; preventing the circulating medium from flowing out through the gap between the shell plates and the baffle plates, facilitating assembly while reducing heat loss and improving heat exchange efficiency.

[0181] Furthermore, the brazing furnace can be selected according to actual needs, and it can be a vacuum furnace, a tunnel furnace, or other equipment that can achieve the welding method of the present application. For example, when used in a vacuum furnace,

[0182] (1) Put the assembled exchanger to be welded as a whole into the vacuum furnace; heat the vacuum furnace to 420°C - 470°C, hold for 20 - 32 min, and apply a vacuum pressure of 1.5 - 2.0 Ebar; make the workpiece uniformly heated; avoid insufficient heat inside the stacked workpieces.

[0183] (2) Heat the vacuum furnace to 860°C - 920°C, hold for 20 - 45 min, and apply a vacuum pressure of 1.5 - 2.0 Ebar; make the workpiece uniformly heated; avoid insufficient heat inside the stacked workpieces.

[0184] (3) Heat the vacuum furnace to 1000°C - 1350°C, hold for 20 - 35 min, and apply a vacuum pressure of 1.5 - 2.0 Ebar; make the workpiece and the welding material uniformly heated; avoid insufficient heat inside the stacked workpieces and uneven temperature of the welding material.

[0185] (4) Heat the vacuum furnace to 1000°C - 1500°C, preferably 1135 degrees, hold for 25 - 55 min, and apply a vacuum pressure of 1.5 - 2.0 Ebar; make the welding material liquefy and perform capillary action in the weld to fill the weld with brazing filler metal; avoid welding defects of the workpiece caused by insufficient time and temperature.

[0186] (5) After the workpiece completes the above heating and holding stages, cool down. When the temperature drops to 50 degrees or below, the vacuum furnace is depressurized, and the integrally welded exchanger is taken out.

[0187] If used in a tunnel furnace, heat the first zone of the tunnel furnace to 980 - 1085°C and set the gas flow rate to 1 - 2.5 L / min.

[0188] The temperature of the second zone of the tunnel furnace is raised to 1020 - 1120 °C, and a gas flow rate of 2 - 4 L / min is set;

[0189] The temperature of the third zone of the tunnel furnace is raised to 1020 - 1120 °C, and a gas flow rate of 2 - 4 L / min is set;

[0190] The temperature of the fourth zone of the tunnel furnace is raised to 1020 - 1120 °C, and a gas flow rate of 2 - 3 L / min is set.

[0191] After welding is completed, take out the integrally welded exchanger, where the speed of the tunnel furnace mesh belt is 160 - 200 mm / min; the cooling water pressure is 0.05 - 0.15 MPa.

[0192] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. Although exemplary embodiments are disclosed in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present invention and to convey the concept of the present invention completely to those skilled in the art.

[0193] In the description of this specification, the descriptions referring to terms such as "certain embodiments", "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0194] In the present invention, the terms "first", "second", and "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance; the term "plural" means two or more, unless otherwise clearly defined. Terms such as "installation", "connection", "connection", and "fixation" should all be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; "connection" can be a direct connection or an indirect connection through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0195] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than being restrictive. Although the present invention has been described in detail with reference to the embodiments, those of ordinary skill in the art should understand that any modification or equivalent replacement of the technical solutions of the present invention does not depart from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A shell and tube heat exchanger with a nickel-chromium alloy medium tube group, characterized in that: Includes internal components welded using a one-piece brazing furnace welding process, including: Baffles; A medium tube group passing through the through hole of the baffle plate and used for energy exchange; The medium pipe group and the baffle plate are clearance-matched and are welded and connected by solder; A collecting cover connected to the medium pipe group; A tube sheet welded to the collecting cover; The medium pipe group is matched with the tube sheet and connected by welding. The medium tube group is made of nickel-chromium alloy.

2. A shell and tube heat exchanger with a nickel-chromium alloy medium tube group according to claim 1, characterized in that: comprising a housing, wherein the internal components are arranged in the housing; The shell includes multiple groups of shell plates; The medium pipe group is arranged in the shell, The medium pipe group is assembled with the shell through the baffle.

3. The shell and tube heat exchanger with a nickel-chromium alloy medium tube group according to claim 1, characterized in that: The current collecting cover comprises a first current collecting cover, an intermediate current collecting cover and a second current collecting cover. The medium pipe group includes multiple groups of medium pipes, The second collecting cover is provided with a second medium port, The second collecting cover is connected to the middle collecting cover through one group of medium pipes of the medium pipe group. and is connected to another group of medium pipes of the medium pipe group through the intermediate collecting cover, Another group of medium pipes of the medium pipe group is connected to the first collecting cover, The first header also includes a first media port.

4. The shell and tube heat exchanger with a nickel-chromium alloy medium tube group according to claim 1, characterized in that: The welding connection method adopted by the tube sheet and the collector is an insertion overlap welding method; The shell, baffles, collecting cover, medium tube group and tube sheet are integrally welded by a brazing furnace, and the shell, baffles, tube sheet and collecting cover of the heat exchanger are all made of metal.

5. A welding process for a shell and tube heat exchanger with a nickel-chromium alloy medium tube group, characterized in that: The following steps are involved: S1, prepare the components of the heat exchanger and inspect them. The components include a first collecting cover, an intermediate collecting cover, a second collecting cover, a shell and a baffle; S2, assembly one, complete the assembly of internal components; S3, assembly 2, complete the overall assembly; S4, putting the assembled heat exchanger into a brazing furnace for one-time welding.

6. A welding process for a shell and tube heat exchanger with a nickel-chromium alloy medium tube group according to claim 5, characterized in that: Step S2 also includes the following steps: S2.1, place the tube sheet and baffles on the assembly tool at the same time; S2.2, assembly between medium pipe group and baffle plate, including: Pass the medium pipe group through the through hole of the baffle plate so that the medium pipe group and the baffle plate match each other. There is a gap between the medium tube group and the baffle, and the gap is filled with solder; S2.3, assembly between medium tube group and tube sheet, including: The medium tube group and the baffle plate are matched; Place the medium pipe solder on the outer diameter of the medium pipe group, The medium pipe group with medium pipe solder is extended into a sunken discharge trough arranged on the tube plate.

7. The welding process of a shell and tube heat exchanger with a nickel-chromium alloy medium tube group according to claim 5, characterized in that: Step S3 also includes assembling the shell by multiple sets of shell plates, placing the internal components in step S2 in the shell, Assembling the shell onto the tube sheet of the internal assembly; The collecting cover and the tube sheet are assembled.

8. The welding process of a shell and tube heat exchanger with a nickel-chromium alloy medium tube group according to claim 7, characterized in that: Inserting and overlapping the first collecting cover, the middle collecting cover, and the second collecting cover with the tube sheet; The sinking groove is opened at the joint position between the collecting cover and the tube plate by filling the solder in the sinking groove.

9. The welding process of a shell and tube heat exchanger with a nickel-chromium alloy medium tube group according to claim 5, characterized in that: Step S3 also The following steps are included: S3-1, the assembly between the shell plate and the baffle plate comprises: Placing solder on the contact points of the shell plates to form a first solder filling layer; Assembling the plurality of shell plates on the internal components in step S2 respectively, and making the baffle vertical surface and the shell plate end surface closely attached to each other through the first solder filling layer; S3-2, the assembly between the tube sheet and the shell includes: By providing a second welding layer at the joint position of two adjacent groups of shell plates, The second welding layer is spot welded to fix the position and connect the adjacent shell plates to form a shell; A first welding layer is provided at the joint position of the tube sheet and the shell plate, so that the tube sheet and the shell are closely attached; S3-3, assembling the tube sheet and the collecting cover.

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