A heat exchanger helium leak detection device and method

Abstract

The present application belongs to the technical field of heat exchanger leak detection, and particularly relates to a heat exchanger helium leak detection device and method, wherein the heat exchanger helium leak detection device comprises: a helium leak detection secondary side simulation cylinder body, which has cylinder body end covers on the two axial sides and is provided with a cylinder body through hole, and the inner wall of the cylinder body through hole is provided with a sealing groove; a fixing member, which is used for mounting a straight pipe heat exchanger in the helium leak detection secondary side simulation cylinder body; two sealing members, which are respectively mounted in the sealing grooves; two pressing cover plates, which are respectively fixed on the cylinder body end covers, and the axial inner surfaces of the pressing cover plates abut against the sealing members; a closed cavity is formed between the two pressing cover plates, the two sealing members, the straight pipe heat exchanger and the helium leak detection secondary side simulation cylinder body; and a detection interface, which is mounted on the helium leak detection secondary side simulation cylinder body and is in communication with the closed cavity. The present application adopts a full mechanical connection structure to avoid the pollution and cost problems caused by welding sealing, the device can be repeatedly used, and is suitable for occasions with high cleanliness requirements such as nuclear power.

Description

Technical Field

[0001] This invention belongs to the field of heat exchanger leak detection technology, specifically relating to a heat exchanger helium leak detection device and method. Background Technology

[0002] Helium leak detection is one of the most sensitive leak detection methods currently available for industrial applications, capable of detecting leaks as small as 1.0 × 10⁻⁶. -9 ~1.0×10 -12 Pa·m 3 / s level. During the heat exchanger manufacturing process, designers usually require manufacturers to perform helium leak testing on the welds of the heat exchanger tubes and tube sheets, because the quality of the tube and tube sheet welds directly affects the heat exchange efficiency and sealing performance of the primary and secondary loops of the heat exchanger, and is a key process in the equipment manufacturing process.

[0003] For open-structure heat exchangers, the secondary heat exchange side is open and lacks full sealing characteristics, making it difficult to establish an effective sealed cavity. Existing technologies typically require complex temporary sealing solutions, such as welded temporary seals, which not only lead to high costs but may also reduce the actual leak detection rate. Furthermore, for equipment with extremely high cleanliness requirements, such as primary loop heat exchangers in nuclear power plants, the removal of welded temporary seals generates weld slag, dust, and other contaminants, severely affecting the cleanliness of the equipment and presenting numerous drawbacks.

[0004] Therefore, there is an urgent need to design a new type of helium leak detection device to overcome the shortcomings of existing technologies. Summary of the Invention

[0005] This invention addresses the high cost and poor cleanliness issues associated with the conventional method of welding temporary sealing for helium leak detection in open-structure heat exchangers. The aim is to provide a helium leak detection device and method for heat exchangers.

[0006] A heat exchanger helium leak detection device, the heat exchanger helium leak detection device comprising:

[0007] The helium leak detection secondary side simulation cylinder has cylinder end caps on both axial sides. The cylinder end caps have cylinder through holes along the axial direction for the tube sheet to be tested of the straight tube heat exchanger to pass through. The inner wall of the cylinder through hole has a sealing groove, and the outer side of the sealing groove is open.

[0008] A fastener for installing the straight-tube heat exchanger into the helium leak detection secondary side simulation cylinder;

[0009] Two sealing elements are respectively installed in the corresponding sealing grooves, and the circumferential inner wall of the sealing element is used to abut against the circumferential outer wall of the corresponding tube sheet to be tested to form a radial seal;

[0010] Two clamping covers are fixed to the corresponding end caps of the cylinder by fasteners. The axial inner surface of the clamping cover abuts against the corresponding sealing element to compress the sealing element and cause it to deform radially. A closed cavity is formed between the two clamping covers, the two sealing elements, the straight tube heat exchanger, and the helium leak detection secondary simulated cylinder.

[0011] The detection interface is installed on the helium leak detection secondary side simulation cylinder and communicates with the closed cavity. The detection interface is used to connect a vacuum pump for vacuuming operations and to connect a helium source for filling tracer gas operations.

[0012] Optionally, the sealing element is an O-ring, the cross-sectional diameter of which is larger than the groove depth of the sealing groove, so that the O-ring partially protrudes from the inner wall of the cylinder through hole when not under pressure.

[0013] Optionally, the inner axial surface of the pressing cover plate is provided with a ring of pressing protrusions, which abut against the corresponding sealing element.

[0014] Optionally, the helium leak detection secondary side simulation cylinder is equipped with an expansion joint for adjusting the axial clearance during assembly.

[0015] Optionally, the heat exchanger helium leak detection device further includes:

[0016] A pressure gauge is installed on the helium leak detection secondary side simulation cylinder, and the pressure gauge is used to detect the pressure information inside the closed cavity.

[0017] Optionally, the helium leak detection secondary-side simulation cylinder includes:

[0018] A first cylindrical body, having a cylindrical body end cap on one axial side and a first flange on the other axial side;

[0019] The second cylinder has a second flange on one axial side and a cylinder end cap on the other axial side; a sealing plate is provided between the first flange and the second flange and is fixed by fasteners to achieve a sealed connection between the first cylinder and the second cylinder.

[0020] Optionally, the end cap of the second cylinder on the other side of the axial direction is fixed to the straight tube heat exchanger by the fastener.

[0021] Optionally, the fastener is a clamp or a clip, which is fixed to the shell of the straight tube heat exchanger. The clamp or clip is located on one side close to the second shell and is fixed to the shell end cap on the other side of the second shell axially using fasteners.

[0022] Optionally, the fastener is a flange connecting plate, which is connected to the flange of the straight tube heat exchanger. The flange connecting plate is located on one side close to the second cylinder and is fixed to the cylinder end cover on the other side of the second cylinder axially using fasteners.

[0023] Optionally, the sealing plate is a vacuum rubber plate.

[0024] A method for helium leak detection of a heat exchanger, using the helium leak detection device described in this invention, includes:

[0025] S1. The straight tube heat exchanger is installed in the helium leak detection secondary side simulation cylinder using fasteners. The tube sheets to be tested on both sides of the straight tube heat exchanger are exposed on both axial sides of the helium leak detection secondary side simulation cylinder, and the two sealing elements are respectively formed with the circumferential outer wall of the tube sheets to be tested on both sides to form a radial seal.

[0026] S2, a vacuum pump is connected through the detection interface to evacuate the sealed cavity, maintain pressure, and test the negative pressure sealing performance;

[0027] S3. After confirming that the negative pressure sealing is qualified, connect the helium source through the test interface, fill the sealed cavity with tracer gas helium, maintain the pressure and test the positive pressure sealing.

[0028] S4. After confirming that the positive pressure sealing is qualified, perform helium leak testing on the tube sheet end face of the primary side of the straight tube heat exchanger for each tube and tube sheet weld.

[0029] S5. After the test is completed, recover or release the helium gas in the sealed cavity, and remove each component in the reverse order of installation.

[0030] Beneficial effects: The present invention has at least one or more of the following advantages:

[0031] 1. This invention achieves radial sealing between the seal and the outer circumferential wall of the tube sheet by axially pressing the sealing element with a clamping cover plate, causing radial deformation. This structure fully utilizes the radial compression of the seal to compensate for the gap between the tube sheet and the through-hole of the cylinder, resulting in good sealing adaptability and eliminating reliance on the flatness of the tube sheet end face. Simultaneously, a closed cavity is formed between the two clamping cover plates, the two seals, the straight-tube heat exchanger, and the simulated cylinder, completely enclosing the area to be inspected on the secondary side of the heat exchanger, providing a reliable detection space for helium leak detection. The fully mechanical connection structure avoids the pollution and cost issues associated with welding and sealing, and the device is reusable, making it suitable for applications with high cleanliness requirements, such as nuclear power plants.

[0032] 2. The sealing element of this invention uses an O-ring, a standard component, which is low in cost and provides stable and reliable sealing performance. The cross-sectional diameter of the O-ring is set to be greater than the groove depth of the sealing groove, so that a portion of the O-ring protrudes from the inner wall of the cylinder's through-hole in the uncompressed state. When the pressure cover plate is axially pressed, the O-ring is compressed and undergoes radial deformation, with the protruding portion tightly fitting against the circumferential outer wall of the tube sheet, forming a reliable radial sealing interface with excellent sealing effect. Simultaneously, this dimensional relationship ensures that the sealing element has sufficient compression margin, compensating for gap deviations between the tube sheet and the through-hole, as well as minor wear of the sealing element after repeated disassembly and assembly, thus extending the service life of the device.

[0033] 3. The clamping protrusion of the present invention concentrates the axial pressure of the clamping cover plate on the seal to a local area of ​​the seal, making the radial deformation of the seal more concentrated and significant when under pressure. Reliable radial sealing can be achieved with a smaller tightening torque, reducing the difficulty of operation. At the same time, the clamping protrusion can effectively prevent the seal from moving outward or being squeezed outward during the pressure process, and guide the seal material to expand uniformly inward along the radial direction, ensuring that a continuous and pressure-uniform sealing contact zone is formed between the seal and the outer wall of the tube sheet, improving the uniformity and durability of the seal.

[0034] 4. This invention, through the design of an expansion joint, makes the axial length of the helium leak detection secondary side simulation cylinder adjustable. During assembly, the expansion joint can compensate for axial dimensional deviations caused by machining errors, installation errors, or thermal expansion and contraction, avoiding problems such as forced assembly or insufficient compression of seals due to dimensional mismatch. This reduces assembly difficulty and the requirements for the machining accuracy of components. At the same time, the expansion joint can absorb thermal stress caused by temperature changes, preventing the sealing structure from failing due to thermal stress, thus improving the reliability, assembly adaptability, and service life of the device.

[0035] 5. The pressure gauge of this invention can monitor the vacuum and positive pressure in the sealed cavity in real time, allowing operators to intuitively judge the sealing performance of the device without relying on external testing equipment. In negative pressure sealing tests, the sealing performance can be determined by observing the pressure rise value. In positive pressure sealing tests, the sealing performance can be determined by observing whether the pressure drops steadily. The pressure gauge and the helium mass spectrometer leak detector complement each other for verification. The former is used for rapid verification of the overall sealing performance of the sealed cavity, while the latter is used for precise leak detection of single-pipe welds. The combination of the two further improves the accuracy and efficiency of the test.

[0036] 6. This invention sets the helium leak detection secondary side simulation cylinder as a detachable structure composed of a first cylinder and a second cylinder connected by a flange, which facilitates the installation and disassembly of the device. During installation, the two cylinder sections are simply inserted from both sides of the heat exchanger and then joined at the middle flange, eliminating the need for a long axial insertion from the tube sheet end, thus reducing the operating space requirements. At the same time, the flange connection surface forms a second sealing barrier through the sealing plate, which, together with the radial seal at the cylinder end cap, constitutes a double sealing structure, significantly improving the redundancy and reliability of the seal. In addition, the split structure facilitates the processing, transportation, replacement, and maintenance of each component, reducing manufacturing costs and maintenance difficulty. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of one structure of the present invention;

[0038] Figure 2 for Figure 1 A magnified view of a portion of point A in the middle;

[0039] Figure 3 for Figure 1 A magnified view of a portion of point B in the middle;

[0040] Figure 4 This is a schematic diagram of one structure of the second cylinder in this invention;

[0041] Figure 5 for Figure 4 Side view;

[0042] Figure 6 for Figure 1 A magnified view of a portion of the image. Detailed Implementation

[0043] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, so as to better understand the purpose, features and advantages of the present invention. It should be understood that the embodiments shown in the drawings are not intended to limit the scope of the present invention, but are only for illustrating the essential spirit of the technical solution of the present invention.

[0044] In the following description, certain specific details are set forth for the purpose of illustrating various disclosed embodiments in order to provide a thorough understanding of the various disclosed embodiments. However, those skilled in the art will recognize that the embodiments may be practiced without one or more of these specific details. In other instances, well-known apparatuses, structures, and techniques associated with this application may not have been shown or described in detail to avoid unnecessarily obscuring the description of the embodiments.

[0045] Throughout this specification, references to "an embodiment" or "an embodiment" indicate that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Therefore, the appearance of "in an embodiment" or "an embodiment" in various places throughout the specification does not necessarily refer to the same embodiment. Furthermore, a particular feature, structure, or characteristic may be combined in any manner in one or more embodiments.

[0046] In the following description, in order to clearly demonstrate the structure and operation of the present invention, a number of directional terms will be used. However, terms such as "front", "back", "left", "right", "outside", "inside", "outward", "inward", "up", and "down" should be understood as convenient terms and not as limiting terms.

[0047] This invention provides a heat exchanger helium leak detection device, which includes a helium leak detection secondary side simulation cylinder, a fixing component, two sealing components, two pressure cover plates, and a detection interface.

[0048] The helium leak detection secondary side simulation cylinder has cylinder end caps on both sides along the axis. The cylinder end caps have cylinder through holes along the axis for the tube sheet to be tested of the straight tube heat exchanger to pass through. The inner wall of the cylinder through hole has a sealing groove, and the outer side of the sealing groove is open along the axis.

[0049] The fastener is used to install the straight tube heat exchanger in the helium leak detection secondary side simulation cylinder.

[0050] Two seals are installed in their respective sealing grooves, and the inner circumferential wall of the seal is used to abut against the outer circumferential wall of the corresponding tube sheet to be tested to form a radial seal.

[0051] Two clamping covers are fixed to the corresponding cylinder end caps by fasteners. The axial inner surface of the clamping cover abuts against the corresponding seal to compress the seal and cause it to deform radially. A closed cavity is formed between the two clamping covers, the two seals, the straight tube heat exchanger, and the helium leak detection secondary side simulated cylinder.

[0052] The detection interface is installed on the secondary side of the helium leak detection simulation cylinder and is connected to the closed cavity. The detection interface is used to connect a vacuum pump for vacuuming operations and to connect a helium source for filling tracer gas operations.

[0053] The heat exchanger helium leak detection device of the present invention uses a mechanical seal to simulate the secondary side sealed shell, thereby overcoming the problems of difficult sealing, high cost, and poor cleanliness in the prior art. This device can be repeatedly disassembled and used, significantly reducing detection costs and improving sealing performance while ensuring detection accuracy.

[0054] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0055] Reference Figures 1 to 6 The heat exchanger helium leak detection device of the present invention includes a helium leak detection secondary side simulation cylinder, a fixing member 20, two sealing members, two pressing cover plates, and a detection interface 50. The two sealing members are a first sealing member 31 and a second sealing member 32, and the two pressing cover plates are a first pressing cover plate 41 and a second pressing cover plate 42.

[0056] The helium leak detection secondary side simulation cylinder has cylinder end caps on both axial sides, namely the first cylinder end cap 11 and the second cylinder end cap 12. Each cylinder end cap has a cylinder through hole along the axial direction for the tube sheet 91 of the straight tube heat exchanger 90 to be tested to pass through. The inner wall of the cylinder through hole has a sealing groove, and the outer side of the sealing groove is open.

[0057] In specific implementation, the cylinder end cap can adopt a circular ring structure, with the through hole in the middle being the cylinder through hole. A sealing groove is opened on one side end face of the cylinder end cap near the inner wall, and the sealing groove has an end face opening and an inner side opening, so that after the sealing element is placed in the sealing groove, the sealing element can abut against the inner end face of the cylinder end cap on its outer side in the axial direction, and at the same time, the sealing element can abut against the circumferential outer wall of the tube plate 91 to be tested on its inner side in the radial direction.

[0058] In practice, the two cylinder end caps can be pre-welded to the axial sides of the simulated cylinder on the secondary side of the helium leak detection.

[0059] The straight tube heat exchanger 90 is installed in the helium leak detection secondary side simulation cylinder through the fastener 20. After the straight tube heat exchanger 90 is installed, the tube sheets 91 to be tested on both sides of the straight tube heat exchanger 90 are exposed.

[0060] The first sealing element 31 is installed in the sealing groove of the first cylinder end cover 11, and the second sealing element 32 is installed in the sealing groove of the second cylinder end cover 12. The circumferential inner wall of each sealing element is used to abut against the circumferential outer wall of the corresponding tube sheet 91 to be tested to form a radial seal.

[0061] The first clamping cover plate 41 is fixed to the first cylinder end cover 11 by fasteners, and the second clamping cover plate 42 is fixed to the second cylinder end cover 12 by fasteners. The axial inner surface of the first clamping cover plate 41 abuts against the first sealing element 31 to compress the first sealing element 31 and cause it to deform radially. The axial inner surface of the second clamping cover plate 42 abuts against the second sealing element 32 to compress the second sealing element 32 and cause it to deform radially.

[0062] A closed cavity is formed between the first pressing cover plate 41, the second pressing cover plate 42, the first sealing element 31, the second sealing element 32, the straight tube heat exchanger 90, and the helium leak detection secondary side simulation cylinder.

[0063] In practical implementation, the two clamping cover plates can adopt a circular structure with an axial through hole in the middle, so that the tube sheets 91 to be tested on both sides of the straight tube heat exchanger 90 are exposed. Preferably, the inner diameter of the clamping cover plate is the same as the outer diameter of the tube sheet 91 to be tested.

[0064] The detection interface 50 is installed on the helium leak detection secondary side simulation cylinder and is connected to the closed cavity. The detection interface 50 is used to connect a vacuum pump for vacuuming operation and to connect a helium source for filling tracer gas operation.

[0065] This invention achieves radial sealing between the seal and the outer circumferential wall of the tube sheet by setting a sealing groove on the inner wall of the tube sheet through hole and opening it axially outward, and cooperating with the pressure cover plate to axially press the seal to cause radial deformation. The sealing adaptability is good and does not depend on the flatness of the tube sheet end face. At the same time, a closed cavity is formed between the two pressure cover plates, the two seals, the straight tube heat exchanger and the simulated tube sheet, which completely covers the secondary side of the heat exchanger to be inspected, providing a reliable detection space for helium leak detection. The all-mechanical connection structure avoids the pollution and cost problems caused by welding and plugging. The device can be reused and is particularly suitable for high-cleanliness requirements such as nuclear power.

[0066] In one embodiment, both the first sealing element 31 and the second sealing element 32 are O-rings. The cross-sectional diameter of the O-ring is larger than the groove depth of the sealing groove, so that the O-ring partially protrudes from the inner wall of the cylinder through hole when not under pressure.

[0067] In this embodiment, the O-ring is a standard part, which is low in cost and has stable and reliable sealing performance. The cross-sectional diameter of the O-ring is set to be greater than the groove depth of the sealing groove, so that a part of the O-ring protrudes from the inner wall of the cylinder through hole when it is not under pressure. When the pressure cover plate is axially pressed, the O-ring is compressed and undergoes radial deformation. The protruding part fits tightly against the circumferential outer wall of the tube sheet, forming a reliable radial sealing interface. At the same time, this dimensional relationship ensures that the seal has sufficient compression margin, which can compensate for the gap deviation between the tube sheet and the through hole and the slight wear of the seal after multiple disassembly and assembly, thus extending the service life of the device.

[0068] In one embodiment, the axial inner surfaces of the first pressing cover plate 41 and the second pressing cover plate 42 are each provided with a ring of pressing protrusions 43, which abut against the corresponding sealing elements.

[0069] Reference Figure 2 The pressing protrusion 43 on the first pressing cover plate 41 abuts against the axial outer side of the first sealing member 31. (Refer to...) Figure 3 The pressing protrusion 43 on the second pressing cover plate 42 abuts against the axial outer side of the second seal 32.

[0070] In this embodiment, the axial pressure of the pressing cover plate on the seal is concentrated on a local area of ​​the seal by the pressing protrusion 43. This makes the radial deformation of the seal more concentrated and significant when under pressure, and a reliable radial seal can be achieved with a smaller tightening torque, reducing the difficulty of operation. At the same time, the pressing protrusion 43 can effectively prevent the seal from moving outward or being squeezed outward during the pressing process, and guide the seal material to expand uniformly inward along the radial direction, ensuring that a continuous and pressure-uniform sealing contact zone is formed between the seal and the outer wall of the tube sheet, thus improving the uniformity and durability of the seal.

[0071] In one embodiment, reference is made to Figure 1 The helium leak detection secondary side simulation cylinder is equipped with an expansion joint 60, which is used to adjust the axial clearance during assembly.

[0072] The expansion joint 60 in this embodiment makes the axial length of the helium leak detection secondary side simulation cylinder adjustable. During assembly, the expansion joint 60 can compensate for axial dimensional deviations caused by machining errors, installation errors, or thermal expansion and contraction, avoiding problems such as forced assembly or insufficient compression of the seal due to size mismatch, reducing assembly difficulty and the requirements for the machining accuracy of parts. At the same time, the expansion joint 60 can absorb thermal stress caused by temperature changes, preventing the sealing structure from failing due to thermal stress, and improving the reliability, assembly adaptability, and service life of the device.

[0073] In one embodiment, reference is made to Figure 1 The heat exchanger helium leak detection device also includes a pressure gauge 70, which is installed on the secondary side of the helium leak detection simulation cylinder and is used to detect the pressure information inside the closed cavity.

[0074] In this embodiment, the pressure gauge 70 can monitor the vacuum and positive pressure within the sealed cavity in real time, allowing operators to intuitively judge the sealing performance of the device without relying on external testing equipment. In negative pressure sealing tests, the sealing performance can be determined by observing the pressure rise value. In positive pressure sealing tests, the sealing performance can be determined by observing whether the pressure drops steadily. The pressure gauge 70 and the helium mass spectrometer leak detector complement each other for verification. The former is used for rapid verification of the overall sealing performance of the sealed cavity, while the latter is used for precise leak detection of single-pipe welds. The combination of the two further improves the accuracy and efficiency of the test.

[0075] In one embodiment, reference is made to Figure 1 , Figures 4 to 6 The helium leak detection secondary side simulation cylinder includes a first cylinder 13 and a second cylinder 14.

[0076] The first cylinder 13 has a first cylinder end cap 11 on one axial side and a first flange 15 on the other axial side. The second cylinder 14 has a second flange 16 on one axial side and a second cylinder end cap 12 on the other axial side. A sealing plate 17 is provided between the first flange 15 and the second flange 16 and is fixed by fasteners to achieve a sealed connection between the first cylinder 13 and the second cylinder 14.

[0077] In this embodiment, the helium leak detection secondary side simulation cylinder is configured as a detachable structure consisting of a first cylinder 13 and a second cylinder 14 connected by flanges, which facilitates the installation and disassembly of the device. During installation, the two cylinder sections are simply inserted from both sides of the heat exchanger and then joined at the middle flange, eliminating the need for a long axial insertion from the tube sheet end, thus reducing the required operating space. At the same time, the flange connection surface forms a second sealing barrier through the sealing plate 17, which, together with the radial seal at the cylinder end cap, constitutes a double sealing structure, significantly improving the redundancy and reliability of the seal. In addition, the split structure facilitates the processing, transportation, replacement, and maintenance of each component, reducing manufacturing costs and maintenance difficulty.

[0078] In practical implementation, the sealing plate 17 is preferably made of vacuum rubber. Vacuum rubber plates have excellent elasticity and sealing performance. Under the normal pressure applied by the fasteners, they can produce sufficient elastic deformation, which can effectively fill the microscopic uneven surface between the two flanges and form a reliable airtight seal. At the same time, vacuum rubber plates have good high vacuum resistance and low outgassing rate characteristics, which will not introduce additional background signal interference during helium leak detection, ensuring the accuracy of the test results. In addition, vacuum rubber plates are commercially available standard materials, which are inexpensive and easy to replace, reducing the maintenance cost of the device.

[0079] In one embodiment, the second cylinder end cap 12 on the other side of the second cylinder 14 is fixed to the straight tube heat exchanger 90 by a fastener 20.

[0080] In practice, the axial lengths of the two cylinders are set differently, such as... Figure 1 As shown, the axial length of the first cylinder 13 is greater than the axial length of the second cylinder 14. In this case, the detection port 50, expansion joint 60, and pressure gauge 70 are preferably installed on the first cylinder 13 with the longer axial length. The second cylinder 14 with the shorter axial length is used to fix it to the straight tube heat exchanger 90.

[0081] In this embodiment, the axial length of the second cylinder (short cylinder) is set to be less than the axial length of the first cylinder (long cylinder), so that the position of the fastener is closer to the end cap 12 of the second cylinder, which significantly shortens the fixing path and improves the connection rigidity and positioning accuracy between the device and the heat exchanger. The shorter cantilever length reduces the torque amplification effect during the assembly process and reduces the risk of seal failure due to vibration or external impact. At the same time, the short cylinder structure is compact, which facilitates installation and fastening operations in the limited operating space of the heat exchanger, and is especially suitable for working conditions where the space around the tube sheet is limited.

[0082] Of course, when the secondary simulated cylinder of the helium leak detection is not a detachable structure, the fastener can be fixed to any cylinder end cap.

[0083] In one embodiment, the fastener 20 can be a clamp or a clip, which is fixed to the shell of the straight tube heat exchanger 90. The clamp or clip is located on one side near the second cylinder 14 and is fixed to the second cylinder end cap 12 on the other side of the second cylinder 14 by fasteners.

[0084] The fastener 20 can also be a flange connecting plate, which is connected to the flange of the straight tube heat exchanger 90. The flange connecting plate is located on the side close to the second shell 14 and is fixed to the second shell end cover 12 on the other side of the second shell 14 by fasteners.

[0085] The clamp or clip structure in this embodiment is simple and easy to install and remove, does not damage the heat exchanger shell, and can adapt to a certain range of shell diameter deviations. Positioning the clamp / clamp / flange connecting plate near the second cylinder minimizes the lever arm of the fixing point, resulting in a more stable and reliable fixation. Directly fixing the clamp / clamp / flange connecting plate to the cylinder end cover with fasteners clarifies the positioning reference of the short cylinder, ensuring the relative positional accuracy between the short cylinder end cover and the heat exchanger tube sheet, thereby ensuring precise and controllable compression of the seal. Furthermore, this embodiment provides two optional fixing methods: clamp / clamp fixing and flange connecting plate fixing, which can be flexibly selected according to the heat exchanger shell structure, expanding the applicability of the device.

[0086] In specific implementation, refer to Figure 5 The inner surface of the second cylindrical end cover 12 is provided with a plurality of internal threaded holes evenly arranged in the circumferential direction. The fastener can be a bolt that passes through the fixing member 20 and the internal threaded hole. By evenly tightening the bolt, the fixing member 20 and the straight tube heat exchanger 90 connected thereto are fixed to the second cylindrical end cover 12.

[0087] Of course, multiple external threaded holes are uniformly arranged circumferentially on the outer surface of the first cylinder end cap 11 and the second cylinder end cap 12, and multiple bolt through holes are uniformly arranged circumferentially on the first clamping cover plate 41 and the second clamping cover plate 42. The length direction of the bolt through holes is axial, and multiple bolts pass through the bolt through holes and the external threaded holes. By tightening the bolts, the first clamping cover plate 41 applies uniform axial pressure to the first sealing element 31, and the second clamping cover plate 42 applies uniform axial pressure to the second sealing element 32.

[0088] This invention also provides a method for helium leak detection in heat exchangers, which uses the helium leak detection device provided in the above embodiments of this invention to perform helium leak detection, and specifically includes the following steps:

[0089] S1, Device assembly and positioning: The straight tube heat exchanger 90 is installed in the helium leak detection secondary side simulation cylinder using the fastener 20. The tube sheets 91 to be tested on both sides of the straight tube heat exchanger 90 are exposed on both axial sides of the helium leak detection secondary side simulation cylinder, and the two seals are ensured to form radial seals with the circumferential outer walls of the tube sheets 91 to be tested on both sides respectively.

[0090] When the helium leak detection secondary side simulation cylinder has a first cylinder 13 and a second cylinder 14, step S1 preferably includes the following assembly process:

[0091] The straight tube heat exchanger 90 is fixed to the second cylinder end cover 12 on the opposite side of the second cylinder 14 using the fastener 20; the first sealing member 31 is placed in the sealing groove of the first cylinder end cover 11, and the second sealing member 32 is placed in the sealing groove of the second cylinder end cover 12; the first cylinder 13 is inserted from one side of the straight tube heat exchanger 90, and the inner end face of the first pressing cover plate 41 is pressed against the outer end face of the tube sheet 91 to be tested of the straight tube heat exchanger 90, and the first sealing member 31 is pressed and compressed to form an end face seal on one side; the first cylinder 13 is adjusted. In the circumferential orientation, the first flange 15 of the first cylinder 13 is aligned with the second flange 16 of the second cylinder 14. A sealing plate 17 is placed between the first flange 15 and the second flange 16, and fasteners are used to secure the first flange 15 and the second flange 16 together. A second compression cover plate 42 is installed from the other side of the straight tube heat exchanger 90, and the second compression cover plate 42 is fixed to the second cylinder end cover 12 of the second cylinder 14 with fasteners, so that the second sealing element 32 inside the second cylinder end cover 12 of the second cylinder 14 is compressed, forming an end face seal on the other side.

[0092] S2, Negative pressure sealing test: Connect a vacuum pump through test interface 50 to evacuate the sealed cavity, maintain pressure and test the negative pressure sealing performance;

[0093] In practice, the following testing process is preferred:

[0094] Connect the detection interface 50 to the vacuum pump via valves and pipelines; start the vacuum pump to evacuate the sealed cavity; once the vacuum level reaches the predetermined value, close the vacuum pump and valves to maintain the pressure; observe the pressure inside the sealed cavity. If the pressure rise within the specified time meets the preset standard requirements, the negative pressure sealing of the device is deemed qualified.

[0095] S3, Positive pressure sealing test: After confirming that the negative pressure sealing is qualified, connect the helium source through the test interface 50, fill the closed cavity with tracer gas helium, maintain the pressure and test the positive pressure sealing.

[0096] In practice, the following testing process is preferred:

[0097] After confirming that the negative pressure sealing is qualified, switch the detection interface 50 to the helium source; fill the closed cavity with tracer gas helium at the specified pressure, close the valve and maintain the pressure after the pressurization is completed; observe the pressure in the closed cavity. If the pressure is stable within the preset range, the positive pressure sealing of the device is determined to be qualified.

[0098] S4, Helium Leak Detection: After confirming that the positive pressure sealing is qualified, helium leak detection is performed on the tube sheet end face of the primary side of the straight tube heat exchanger 90 one by one on the tube sheet weld.

[0099] In practice, the following testing process is preferred:

[0100] After confirming that the positive pressure sealing is qualified, the operator uses a single-core full absorption electro-dynamic suction gun clamp connected to the helium mass spectrometer leak detector to scan and suck up the weld between each tube and the tube sheet on the tube sheet end face of the primary side of the heat exchanger; the helium mass spectrometer leak detector will display the leakage rate in real time, thereby judging the sealing quality of each weld.

[0101] S5, Device Dismantling: After the test is completed, recover or release the helium gas in the sealed cavity through the test interface 50, and then dismantle each component in the reverse order of installation.

[0102] This embodiment provides a complete operation process from device assembly and sealing verification to weld leak detection and dismantling and recycling. The operation steps are clear and the sequence is reasonable. S2 and S3 respectively perform negative pressure sealing test and positive pressure sealing test, forming a dual verification mechanism to ensure that the device itself is fully qualified before formal helium leak detection, avoiding the risk of misjudging weld leaks due to device leakage, and ensuring the authenticity and reliability of the test results. In S4, a single-core full-absorption electro-dynamic suction gun is used to scan tube by tube, which can realize accurate leak detection and quantitative leakage rate of each tube and tube sheet weld, with accurate positioning and high detection sensitivity. In S5, the dismantling process of the fully mechanical connection does not generate weld slag, dust and other pollutants. Each component can be properly stored for reuse, which is especially suitable for occasions with high cleanliness requirements and batch testing, such as nuclear power products, and significantly reduces the overall cost of a single test.

[0103] The preferred embodiments of the present invention have been described in detail above. However, it should be understood that after reading the above teachings, those skilled in the art can make various alterations or modifications to the present invention. These equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A helium leak detection device for a heat exchanger, characterized in that, The heat exchanger helium leak detection device includes: The helium leak detection secondary side simulation cylinder has cylinder end caps on both axial sides. The cylinder end caps have cylinder through holes along the axial direction for the tube sheet to be tested of the straight tube heat exchanger to pass through. The inner wall of the cylinder through hole has a sealing groove, and the outer side of the sealing groove is open. A fastener for installing the straight-tube heat exchanger into the helium leak detection secondary side simulation cylinder; Two sealing elements are respectively installed in the corresponding sealing grooves, and the circumferential inner wall of the sealing element is used to abut against the circumferential outer wall of the corresponding tube sheet to be tested to form a radial seal; Two clamping covers are fixed to the corresponding end caps of the cylinder by fasteners. The axial inner surface of the clamping cover abuts against the corresponding sealing element to compress the sealing element and cause it to deform radially. A closed cavity is formed between the two clamping covers, the two sealing elements, the straight tube heat exchanger, and the helium leak detection secondary simulated cylinder. The detection interface is installed on the helium leak detection secondary side simulation cylinder and communicates with the closed cavity. The detection interface is used to connect a vacuum pump for vacuuming operations and to connect a helium source for filling tracer gas operations.

2. The heat exchanger helium leak detection device as described in claim 1, characterized in that, The sealing element is an O-ring, and the cross-sectional diameter of the O-ring is larger than the groove depth of the sealing groove, so that the O-ring partially protrudes from the inner wall of the cylinder through hole when not under pressure.

3. The heat exchanger helium leak detection device as described in claim 1, characterized in that, The inner axial surface of the pressure cover plate is provided with a ring of pressure protrusions, which abut against the corresponding sealing element.

4. The heat exchanger helium leak detection device as described in claim 1, characterized in that, The helium leak detection secondary side simulation cylinder is equipped with an expansion joint for adjusting the axial clearance during assembly.

5. The heat exchanger helium leak detection device as described in claim 1, characterized in that, The heat exchanger helium leak detection device also includes: A pressure gauge is installed on the helium leak detection secondary side simulation cylinder, and the pressure gauge is used to detect the pressure information inside the closed cavity.

6. The heat exchanger helium leak detection device as described in any one of claims 1 to 5, characterized in that, The helium leak detection secondary side simulation cylinder includes: A first cylindrical body, having a cylindrical body end cap on one axial side and a first flange on the other axial side; The second cylinder has a second flange on one axial side and a cylinder end cap on the other axial side; a sealing plate is provided between the first flange and the second flange and is fixed by fasteners to achieve a sealed connection between the first cylinder and the second cylinder.

7. The heat exchanger helium leak detection device as described in claim 6, characterized in that, The end cap of the second cylinder on the other side of the axial direction is fixed to the straight tube heat exchanger by the fixing member.

8. The heat exchanger helium leak detection device as described in claim 7, characterized in that, The fastener is a clamp or a clip, which is fixed to the shell of the straight tube heat exchanger. The clamp or clip is located on one side close to the second cylinder and is fixed to the cylinder end cap on the other side of the second cylinder axially using fasteners. Alternatively, the fastener is a flange connecting plate, which is connected to the flange of the straight tube heat exchanger. The flange connecting plate is located on one side close to the second cylinder and is fixed to the cylinder end cover on the other side of the second cylinder axially using fasteners.

9. The heat exchanger helium leak detection device as described in claim 6, characterized in that, The sealing plate is made of vacuum rubber.

10. A method for helium leak detection in a heat exchanger, characterized in that, Helium leak detection using the heat exchanger helium leak detection device according to any one of claims 1 to 9 includes: S1. The straight tube heat exchanger is installed in the helium leak detection secondary side simulation cylinder using fasteners. The tube sheets to be tested on both sides of the straight tube heat exchanger are exposed on both axial sides of the helium leak detection secondary side simulation cylinder, and the two sealing elements are respectively formed with the circumferential outer wall of the tube sheets to be tested on both sides to form a radial seal. S2, a vacuum pump is connected through the detection interface to evacuate the sealed cavity, maintain pressure, and test the negative pressure sealing performance; S3. After confirming that the negative pressure sealing is qualified, connect the helium source through the test interface, fill the sealed cavity with tracer gas helium, maintain the pressure and test the positive pressure sealing. S4. After confirming that the positive pressure sealing is qualified, perform helium leak testing on the tube sheet end face of the primary side of the straight tube heat exchanger for each tube and tube sheet weld. S5. After the test is completed, recover or release the helium gas in the sealed cavity, and remove each component in the reverse order of installation.

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