Leak detection device and method for a shell-and-tube heat exchanger

Abstract

The present invention provides a leak detection device and a leak detection method for a shell-and-tube heat exchanger. The device includes a voltage stabilization module, a detection module, and a water storage module. The detection module includes a plurality of vacuum covers, which are respectively arranged at both ends of the heat transfer tubes to be detected. The vacuum cover at one end of the heat transfer tube to be detected is connected to the voltage stabilization module, and the vacuum cover at the other end is connected to the water storage module; the vacuum cover is a transparent part. In the present invention, a voltage stabilization module, a detection module, and a water storage module are provided. The detection module includes vacuum covers arranged at both ends of the heat transfer tubes to be detected. The voltage stabilization module evacuates the interior of the heat transfer tubes to be detected through the vacuum covers, and the water storage module injects water into the interior of the heat transfer tubes to be detected. The device and method of the present application detect multiple heat transfer tubes with the same isolation boundary simultaneously, improving the detection efficiency; taking the continuous generation of bubbles as the identification mark of the leakage signal to eliminate the interference under unstable states and improving the detection accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of heat exchanger detection devices, and particularly to a leak detection device and a leak detection method for a shell-and-tube heat exchanger. Background Art

[0002] The structure of a shell-and-tube heat exchanger mainly consists of a shell, end plates at both ends of the shell, and tube bundles installed inside the shell. The outer circular surfaces at both ends of the tube bundles are hermetically connected to the end plates, and the wall surface of the tube bundle enclosed in the shell is used as the heat transfer surface. The main manufacturing materials are carbon steel, stainless steel, and copper. During manufacturing, manual arc welding is generally used for welding the tube sheet and the tube bundle. The weld shapes have various degrees of defects, such as depressions, pores, slag inclusions, etc., and the distribution of weld stresses is also uneven. Leakage is likely to occur after long-term operation; at the same time, the heat transfer tubes are relatively slender and are prone to perforation-type leak points after being impacted by fluid and vibrating.

[0003] Leakage detection is mainly applied to the detection work for ensuring the safe operation of pressure-bearing components or equipment and systems operating in a vacuum environment. Conventional leakage detection techniques include the positive pressure helium sucking method, the vacuum helium spraying method, and the pressure change method.

[0004] For the detection of open pressure-bearing components, the detection method mainly involves contact detection of suspected leak points, and tracer gas is applied for positioning to determine the specific location; however, for the inspection of heat transfer tubes inside closed containers such as shell-and-tube heat exchangers, due to the inaccessibility of personnel and equipment, the use is limited; the positive pressure helium sucking method and the vacuum helium spraying method using helium leak detection have the problem of difficult boundary isolation.

[0005] The pressure change method generally uses the static pressure rise method or the static pressure drop method to detect the heat transfer tubes. During detection, plugs are used to block both ends of the heat transfer tubes. However, due to the process limitations of the plugs and the conditions of the tube sheet, the tube sheet circumferential welds cannot be detected and the observed phenomena are not obvious, and it is easy to cause missed detection and false detection of the sealed weld between the heat transfer tube and the tube sheet due to human error; at the same time, when using such methods for detecting the heat transfer tube bundles of shell-and-tube heat exchanger equipment, they are usually carried out in the way of checking each tube one by one, with low efficiency, unobvious effects, and great limitations. Summary of the Invention

[0006] In view of the above-mentioned disadvantages of the prior art, the purpose of the present invention is to provide a leak detection device and a leak detection method for a shell-and-tube heat exchanger, which are used to solve the problems of limited use, difficult boundary isolation existing in the prior art when using the positive pressure helium sucking method and the vacuum helium spraying method, and the problems of inability to detect tube sheet circumferential welds and low efficiency existing in the pressure change method.

[0007] To achieve the above and other related purposes, the present invention provides a leak detection device for a shell-and-tube heat exchanger, including a pressure stabilization module, a detection module, and a water storage module. The detection module includes a plurality of vacuum covers, which are respectively arranged at both ends of the heat transfer tube to be detected. The vacuum cover at one end of the heat transfer tube to be detected is connected to the pressure stabilization module, and the vacuum cover at the other end is connected to the water storage module; the vacuum cover is a transparent member.

[0008] Preferably, the pressure stabilization module includes an air extraction component, a gas-liquid separation component, and a pressure monitoring component. The gas-liquid separation component is respectively connected to the air extraction component and the pressure monitoring component through a gas guide pipe, and the gas-liquid separation component is communicated with the vacuum cover at one end of the heat transfer tube to be detected through an air extraction pipeline.

[0009] Preferably, a branch pipe is further arranged on the gas guide pipe between the gas-liquid separation component and the pressure monitoring component. The branch pipe is communicated with the atmosphere, and a pressure control valve is arranged on the branch pipe.

[0010] Preferably, the water storage module includes a water storage tank, a circulation pump, a flow controller, and a water injection circuit pipe. The water injection circuit pipe connects the water storage tank and the vacuum cover at one end of the detection module; a water injection control valve is further arranged on the water injection circuit pipe, and the circulation pump is installed in the water storage tank; the circulation pump, the flow controller, and the water injection control valve are sequentially arranged on the water injection circuit pipe.

[0011] Preferably, the water storage module further includes a circulating water circuit pipe, which connects the water storage tank and the vacuum cover connected with the water injection circuit pipe and a circulating water control valve is further arranged on the circulating water circuit pipe.

[0012] Preferably, an air outlet is arranged on the vacuum cover connected to the pressure stabilization module, and an inlet / outlet is arranged on the vacuum cover connected to the water storage module.

[0013] Preferably, the leak detection device for the shell-and-tube heat exchanger further includes a calibration module, which includes a calibration circuit and a calibration component. The calibration component is connected to the vacuum cover connected with the water storage module through the calibration circuit; a calibration control valve is further arranged on the calibration circuit.

[0014] Preferably, the calibration component is a standard leak hole component.

[0015] Preferably, a plurality of the vacuum covers are hermetically connected to both ends of the heat transfer tube to be detected.

[0016] To achieve the above and other related purposes, the present invention also provides a leak detection method for a shell-and-tube heat exchanger, which uses the leak detection device for the shell-and-tube heat exchanger, and the specific steps are as follows:

[0017] A1: Install vacuum covers at both ends of the heat transfer tube to be detected. The vacuum cover at one end of the heat transfer tube to be detected is connected to the pressure stabilizing module, and the vacuum cover at the other end is connected to the water storage module.

[0018] A2: Start the pressure stabilizing module to establish the vacuum degree inside the heat transfer tube to be detected.

[0019] A3: Start the water storage module to inject water into the heat transfer tube to be detected.

[0020] A4: Observe whether there are bubbles through the vacuum cover at the connection with the pressure stabilizing module. If there are bubbles, there is a leakage point; if there are no bubbles, there is no leakage point.

[0021] As described above, the leak detection device and method for a shell-and-tube heat exchanger of the present invention have the following beneficial effects:

[0022] The leak detection device and method for a shell-and-tube heat exchanger of the present invention are provided with a pressure stabilizing module, a detection module, and a water storage module. The detection module includes vacuum covers arranged at both ends of the heat transfer tube to be detected. The pressure stabilizing module evacuates the inside of the heat transfer tube to be detected through the vacuum covers, and the water storage module injects water into the inside of the heat transfer tube to be detected. Under the condition of continuous vacuum pumping, if there is a leakage point in the heat transfer tube to be detected, due to the pressure difference between the inside and outside of the heat transfer tube to be detected, gas will enter the inside of the heat transfer tube from the leakage point, thus generating bubbles in the vacuum cover, and then it can be judged that the heat transfer tube to be detected has a leak. By using the device and method of the present application, multiple heat transfer tubes with the same isolation boundary can be detected simultaneously, improving the detection efficiency; taking the continuous generation of bubbles as the identification mark of the leakage signal to eliminate the interference under unstable conditions and improve the detection accuracy; the vacuum cover can wrap the ends of the heat transfer tube to be detected and can detect the welds at the ends of the heat transfer tube to be detected, with a wide range of applications. Description of the Drawings

[0023] Figure 1 It is a working schematic diagram of the leak detection device for the shell-and-tube heat exchanger of the present invention;

[0024] Figure 2 It is a structural schematic diagram of the heat transfer tube to be detected of the leak detection device for the shell-and-tube heat exchanger of the present invention;

[0025] Figure 3 It is a working flowchart of the leak detection method for the shell-and-tube heat exchanger of the present invention.

[0026] Description of the reference numerals:

[0027] 1. Voltage stabilizing module; 101. Air extraction component; 102. Gas-liquid separation component; 103. Pressure monitoring component; 104. Pressure control valve; 2. Detection module; 201. Heat transfer tube to be detected; 202. Upper vacuum cover; 203. Lower vacuum cover; 204. Air extraction pipeline; 205. Air outlet; 206. Inlet / outlet water port; 207. Leak point; 3. Water storage module; 301. Water storage tank; 302. Circulation pump; 303. Flow controller; 304. Water injection control valve; 305. Circulating water control valve; 306. Water injection loop pipe; 307. Circulating water loop pipe; 308. Liquid guide pipe; 4. Calibration module; 401. Calibration control valve; 402. Calibration component; 403. Calibration loop. Detailed implementation mode

[0028] The following is a specific example to illustrate the implementation mode of the present invention. Those familiar with this technology can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0029] It should be noted that the structures, ratios, sizes, etc. shown in the drawings of this specification are only used to cooperate with the content disclosed in the specification for those familiar with this technology to understand and read, and are not used to limit the limited conditions under which the present invention can be implemented. Therefore, they do not have technical essence. Any modification of the structure, change of the proportional relationship or adjustment of the size, without affecting the expected effect and the purpose that the present invention can achieve, should still fall within the scope covered by the technical content disclosed in the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" cited in this specification are only for the convenience of clear narration, and are not used to limit the scope under which the present invention can be implemented. The change or adjustment of their relative relationship, without substantial change in the technical content, should also be regarded as the scope within which the present invention can be implemented.

[0030] As Figure 1 shown, the present invention provides a leak detection device for a shell-and-tube heat exchanger, including a voltage stabilizing module 1, a detection module 2, and a water storage module 3. The detection module 2 includes a plurality of vacuum covers, which are respectively hermetically installed at both ends of the heat transfer tube 201 to be detected. The vacuum cover at one end of the heat transfer tube 201 to be detected is connected to the voltage stabilizing module 1, and the vacuum cover at the other end is connected to the water storage module 3; the vacuum cover is a transparent part.

[0031] The leak detection device for the shell-and-tube heat exchanger involved in the present invention (hereinafter referred to as the leak detection device) is provided with a voltage stabilization module 1, a detection module 2, and a water storage module 3. The inside of the heat transfer tube 201 to be detected is made in a vacuum state through the voltage stabilization module 1, and water is injected into the inside of the heat transfer tube 201 to be detected through the water storage module 3. When there is a leak point 207 in the heat transfer tube 201 to be detected, due to the air pressure difference inside and outside the heat transfer tube 201 to be detected, air will enter the inside of the heat transfer tube 201 from the leak point 207. The operator can observe whether there are bubbles through the transparent vacuum hood, so as to judge whether there is a leak point 207 in the heat transfer tube 201 to be detected.

[0032] For the leak detection device of the shell-and-tube heat exchanger involved in the present invention, transparent vacuum hoods are arranged at both ends of the heat transfer tube 201 to be detected. Whether there is a leak point 207 is judged by whether bubbles are generated under the vacuum condition of the heat transfer tube 201 to be detected, eliminating the interference of the existing detection method under the unstable state. The vacuum hoods wrap the welds at both ends of the heat transfer tube 201 to be detected, overcoming the defect that the static pressure rise method or the static pressure drop method cannot detect the end welds. With this leak detection device, the vacuum hoods can simultaneously detect multiple heat transfer tubes 201 to be detected, and the detection efficiency is high. With this leak detection device, the generated bubbles can be directly observed, and it can be directly determined whether there is a leak point 207 in the area to be detected inside the transparent vacuum hood, and the size and position of the leak point 207 can be quickly determined, avoiding the use of the dichotomy method to determine the leak point 207, greatly shortening the detection time; at the same time, multiple heat transfer tubes 201 to be detected can also be detected together, and the heat transfer tubes 201 with leaks can be quickly found according to whether bubbles appear, improving the detection efficiency.

[0033] Preferably, as Figure 2 shown, in this embodiment, the shape of the heat transfer tube 201 to be detected is U-shaped. The vacuum hood connected to the upper opening of the U-shaped heat transfer tube is the upper vacuum hood 202, and the vacuum hood connected to the lower opening of the U-shaped heat transfer tube is the lower vacuum hood 203.

[0034] Preferably, as Figure 1 shown, the voltage stabilization module 1 includes an air extraction component 101, a gas-liquid separation component 102, and a pressure monitoring component 103. The gas-liquid separation component 102 is respectively connected to the air extraction component 101 and the pressure monitoring component 103 through air ducts. The gas-liquid separation component 102 is communicated with the upper vacuum hood 202 through an air extraction pipeline 204. Further, the air extraction component 101 is used to provide the power source for evacuating the heat transfer tube 201 to be detected; the gas-liquid separation component 102 is used to separate water and gas from the medium to protect the air extraction component 101; the pressure monitoring component 103 is used to monitor the pressure in the gas-liquid separation component 102 in real time and adjust the vacuum pressure state in the gas-liquid separation component 102 at any time.

[0035] Preferably, as Figure 1As shown, a branch pipe is also provided on the air duct between the gas-liquid separation component 102 and the pressure monitoring component 103. The branch pipe is connected to the atmosphere, and a pressure control valve 104 is provided on the branch pipe. In this embodiment, the branch pipe is connected to the atmosphere, and a pressure control valve 104 is provided on the branch pipe. The operator uses the pressure control valve 104 to adjust the pressure in the gas-liquid separation component 102 on the one hand, and on the other hand, after the detection is completed, the gas-liquid separation component 102 is connected to the atmosphere to restore the pressure in the gas-liquid separation component 102. Further, in this embodiment, the vacuum degree in the gas-liquid separation component 102 needs to be maintained within the range of -0.05 ± 0.01 MPa.

[0036] Preferably, as Figure 1 shown, the water storage module 3 includes a water storage tank 301, a circulation pump 302, a flow controller 303, and a water injection circuit pipe 306. The water injection circuit pipe 306 connects the water storage tank 301 and the lower vacuum cover 203; a water injection control valve 304 is also provided on the water injection circuit pipe 306. The circulation pump 302 is installed in the water storage tank 301; the circulation pump 302, the flow controller 303, and the water injection control valve 304 are sequentially provided on the water injection circuit pipe 306. Further, in this embodiment, the water in the water storage tank 301 enters the heat transfer tube 201 to be detected through the circulation pump 302 → the flow controller 303 → the water injection control valve 304 → the lower vacuum cover 203. The flow controller 303 is used to control the flow rate of water, on the one hand, to prevent the upper vacuum cover 202 from being washed away by too fast water injection, and on the other hand, to prevent bubbles from being generated in the water due to too fast water injection, which affects the accuracy of leak detection. The water storage module 3 is mainly used to inject water medium into the heat transfer tube 201 to be detected and store the water medium after the test is completed.

[0037] Preferably, as Figure 1 shown, the water storage module 3 further includes a circulating water circuit pipe 307. The circulating water circuit pipe 307 connects the water storage tank 301 and the lower vacuum cover 203, and a circulating water control valve 305 is also provided on the circulating water circuit pipe 307. Further, in this embodiment, the circulating water circuit pipe 307 is connected as a branch to the water injection circuit pipe 306, and the opening and closing of the circulating water circuit pipe 307 is controlled by the circulating water control valve 305.

[0038] Preferably, as Figure 1 shown, an air outlet 205 is provided on the upper vacuum cover 202, and an inlet / outlet 206 is provided on the lower vacuum cover 203. In this embodiment, the gas-liquid separator is connected to the upper vacuum cover 202 through a suction pipe 204 and the air outlet 205, and the water storage tank 301 is connected to the lower vacuum cover 203 through the water injection circuit pipe 306 and the inlet / outlet 206.

[0039] Preferably, as Figure 1As shown, the leak detection device of the shell-and-tube heat exchanger further includes a calibration module 4. The calibration module 4 includes a calibration loop 403 and a calibration component 402. The calibration component 402 is connected to the lower vacuum cover 203 through the calibration loop 403. A calibration control valve 401 is also provided on the calibration loop 403. Further, in this embodiment, the calibration loop 403 is also connected to the water injection loop pipe 306 as a branch. Further, the calibration component 402 is a standard leak hole component. The calibration module 4 is used for system calibration to provide a reference for subsequent leak detection.

[0040] Preferably, as Figure 1 , Figure 2 shown, several vacuum covers are hermetically connected to both ends of the heat transfer tube 201 to be detected. In this embodiment, the number of vacuum covers is two, and in this embodiment, the vacuum covers are hermetically connected to the ends of the heat transfer tube 201 to be detected by evacuating.

[0041] Preferably, as Figure 1 shown, the gas-liquid separation component 102 and the water storage tank 301 are also connected through a liquid guide pipe 308, and a valve (not shown) is installed on the liquid guide pipe 308.

[0042] To achieve the above and other related purposes, the present invention also provides a method for detecting leaks in a shell-and-tube heat exchanger, using the above-mentioned leak detection device of the shell-and-tube heat exchanger. As Figure 3 shown, the specific steps are as follows:

[0043] A1: Connect the above-mentioned components. As Figure 1 shown, connect the components of each module, and confirm that the initial state of each control valve is closed.

[0044] A2: Establish a vacuum degree. As Figure 1 shown, specifically: Start the air extraction component 101. The air extraction component 101 works to extract the air in the gas-liquid separation component 102. Under the action of atmospheric pressure, the air in the heat transfer tube 201 to be detected is extracted through the air extraction pipeline 204, and the heat transfer tube 201 to be detected is in a vacuum environment. The pressure monitoring component 103 is used to detect the vacuum degree in the gas-liquid separation component 102 and adjust the opening degree of the pressure control valve 104 so that the vacuum degree in the gas-liquid separation component 102 is -0.05 ± 0.01 MPa. If the pressure monitoring component 103 detects that the vacuum degree in the gas-liquid separation component 102 is within the above range and remains unchanged within a certain period of time, it proves that the vacuum degree is qualified; if the pressure monitoring component 103 detects that the air pressure in the gas-liquid separation component 102 cannot always be within the above range, or the pressure changes significantly within a certain period of time, it proves that the vacuum degree is unqualified, and it is necessary to check the components connected in step A1 and the boundaries of the vacuum covers to ensure tightness until the vacuum degree detected by the pressure monitoring component 103 is qualified.

[0045] A3: Water injection. As Figure 1 shown, open the water injection control valve 304 on the water injection circuit pipe 306, turn on the circulation pump 302. The circulation pump 302 operates, and the water in the water storage tank 301 passes through → the circulation pump 302 → the flow controller 303 → the water injection control valve 304 → the lower vacuum hood 203 and enters the heat transfer pipe 201 to be detected until the water level submerges the upper pipe orifice of the heat transfer pipe 201 to be detected. After the water injection is completed, close the water injection control valve 304. During the water injection process, the flow controller 303 controls the water injection flow rate. On the one hand, it avoids washing off the upper vacuum hood 202 due to too fast water injection; on the other hand, it avoids generating bubbles in the water due to too fast water injection, which affects the accuracy of leak detection.

[0046] A4: System calibration. As Figure 1 shown, adjust the pressure control valve 104 to keep the vacuum degree detected by the pressure monitoring component 103 at -0.05 ± 0.01 MPa and hold the pressure for a period of time (about 5 min). If no bubbles are generated, install the standard leak hole component at the calibration component 402, open the calibration control valve 401 for system calibration, so as to determine the system sensitivity. Specifically: install the standard leak hole component and open the calibration control valve 401, the calibration circuit 403 is connected. Under the action of the atmospheric pressure difference, air passes through the standard leak hole component → the calibration control valve 401 → the calibration circuit 403 → into the heat transfer pipe 201 to be detected, and bubbles appear at the lower vacuum hood 203. Record the time t1 when the bubbles appear at this time; under the action of the air pressure difference, the bubbles flow, aggregate and grow larger in the heat transfer pipe 201 to be detected. When bubbles appear at the upper vacuum hood 202, record the time t2 when the bubbles appear at this time; therefore, the reaction time of the bubbles in the heat transfer pipe 201 to be detected is △t0 (i.e., t2 - t1), and thus the movement speed s of the bubbles in the heat transfer pipe 201 to be detected can be calculated as s = (the length of the heat transfer pipe 201 to be detected / △t0). If no bubbles are observed in the lower vacuum hood 203 after installing the calibration leak hole component, replace the standard leak hole component with a larger leak rate and repeat the above steps. After the calibration is completed, close the calibration control valve 401. The system calibration steps are only executed during the first leak detection.

[0047] A5: Leak detection. Connect the heat transfer pipe 201 to be detected to this leak detection device, adjust the pressure control valve 104 to keep the vacuum degree detected by the pressure monitoring component 103 at -0.05 ± 0.01 MPa. Take 1.5 to 2.5 times the reaction time △t0 in the calibrated state as the observation time △t for routine detection. If no continuous bubble generation phenomenon is observed in the upper vacuum hood 202 within the observation time △t, it is determined that this heat transfer pipe 201 to be detected has no problem, record it as qualified, and proceed with subsequent operations; if the continuous bubble generation phenomenon is observed in the upper vacuum hood 202 and record the relevant positions, it is determined as unqualified.

[0048] A5.1: In this embodiment, multiple heat transfer tubes 201 to be detected can be connected to the upper vacuum cover 202 and the lower vacuum cover 203 at one time. By checking whether bubbles appear in the upper vacuum cover 202 through each heat transfer tube 201 to be detected, it can be quickly determined whether there is a leakage point 207 in the heat transfer tube 201 to be detected. At the same time, based on the time difference T between adjacent bubbles, the position of the leakage point 207 can be roughly estimated. Specifically: the distance between the leakage point 207 and the upper vacuum cover 202 = (the time difference T between adjacent bubbles * the moving speed s of the bubbles).

[0049] A6: Pressure relief. After all the heat transfer tubes 201 to be detected are detected, as Figure 1 shown, the air extraction component 101 is closed, and the pressure control valve 104 is opened to restore the vacuum degree in the gas-liquid separation component 102 to the atmospheric pressure state.

[0050] A7: Drainage. When the air pressure in the gas-liquid separation component 102 returns to the atmospheric pressure, the circulating water control valve 305 is opened, and the water in the heat transfer tube 201 to be detected is drained into the water storage tank 301 through the circulating water circuit pipe 307. The heat transfer tube 201 to be detected is disassembled to prepare for the next group of detections.

[0051] A7.1: In this embodiment, during the leakage detection process, the gas-liquid separation component 102 collects the water overflowing from the upper vacuum cover 202. After the detection is completed, the valve on the liquid guide pipe 308 between the gas-liquid separation component 102 and the water storage tank 301 is opened to allow the water in the gas-liquid separation component 102 to enter the water storage tank 301.

[0052] Regarding the leak detection device for the shell-and-tube heat exchanger of the present invention, the gas outside the leakage point 207 in the negative pressure environment will enter the heat transfer tube 201 to be detected due to the pressure difference. When the heat transfer tube 201 to be detected is filled with water and stabilized, the bubbles will move directionally due to the pressure difference inside the heat transfer tube, and continuous bubbles will be generated at the upper vacuum cover 202 after a period of time; using this characteristic, this leak detection device is manufactured. As Figure 2 shown, the gas enters the interior of the heat transfer tube 201 to be detected through the leakage point 207 and forms bubbles in the water. The bubbles grow, gather, move directionally, and burst at the upper vacuum cover 202 under the action of the pressure difference; the size of the leakage point 207 is initially determined by the speed of the bubbles appearing, and the distance between the leakage point 207 and the upper vacuum cover 202 is initially determined by the time difference between adjacent bubbles to judge the approximate position of the leakage point 207.

[0053] The leak detection device for the shell-and-tube heat exchanger of the present invention adopts the following technical means to produce the following technical effects, specifically as follows:

[0054] 1. A transparent vacuum cover is used to isolate the boundary of the port of the heat transfer tube 201 to be detected, and a sealed cavity is formed for the heat transfer tube 201 to be detected through the vacuum cover. Utilizing the characteristics of negative pressure, the presence of bubbles in the vacuum cover is observed, and the detection area covers the tube sheet circumferential weld, enabling the detection of the weld and eliminating the defect that the plug is used for boundary isolation in detection techniques such as the static pressure rise method or the static pressure drop method and the weld cannot be detected.

[0055] 2. The vacuum cover is used to conduct parallel detection on multiple heat transfer tubes 201 to be detected, eliminating the situation where the detection module 2 is unavailable due to differences in heat exchanger types, heat transfer tube diameters, and heat transfer tube arrangement methods, and improving the scope of use. Detecting multiple heat transfer tubes 201 to be detected simultaneously improves the detection efficiency.

[0056] 3. The gas-liquid separation component 102 and the pressure monitoring component 103 are used to achieve real-time monitoring and control.

[0057] 4. The water storage module 3 is adopted to increase the availability of the detection medium. The detection medium is homologous with the cooling medium, is not restricted by the environment, and has strong compatibility.

[0058] 5. After connecting all components, a standard leak hole component is used to test the sensitivity and response time to ensure accuracy. After calibration tests are carried out with the standard leak hole component, the leak detection method for this shell-and-tube heat exchanger can effectively detect leak points 207 with a leakage rate of 10 -3 Pa·m 3 / s, meeting the requirements of engineering applications.

[0059] 6. Using the continuous generation of bubbles at the upper vacuum cover 202 as the identification mark for confirming the leak point 207, interference in the unstable state is excluded, and the phenomenon is obvious and easy to judge.

[0060] 7. According to the speed and size of the bubbles generated at the leak point 207, the leakage rate level of the leak point 207 can be approximately determined.

[0061] 8. By using a transparent vacuum cover, it is possible to directly determine whether there is a leak point 207 in the heat transfer tube 201 to be detected and the approximate position of the leak point 207 based on the observed bubbles, avoiding the use of the dichotomy method to determine the presence of the leak point 207, greatly shortening the detection time, and making a semi-quantitative estimate of the leak point 207 by referring to the rate and size of the bubbles generated by the standard leak hole component, which is fast and convenient.

[0062] Therefore, the present invention effectively overcomes various shortcomings in the prior art and has high industrial utilization value.

[0063] The above embodiments are only illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A method for detecting leaks in a shell-and-tube heat exchanger, characterized in that: A leak detection device for a shell-and-tube heat exchanger, the leak detection device for the shell-and-tube heat exchanger comprising a pressure stabilization module (1), a detection module (2), and a water storage module (3). The detection module (2) comprises a plurality of vacuum covers which are respectively arranged at both ends of a heat transfer tube to be detected (201). The vacuum cover at one end of the heat transfer tube to be detected (201) is connected to the pressure stabilization module (1), and the vacuum cover at the other end is connected to the water storage module (3). The vacuum cover is a transparent member. The number of heat transfer tubes to be detected (201) is multiple, and the multiple heat transfer tubes to be detected (201) have the same isolation boundary. The leak detection device for the shell-and-tube heat exchanger detects the multiple heat transfer tubes to be detected (201) simultaneously. The specific steps are as follows: A1: Install the vacuum covers at both ends of the heat transfer tube to be detected (201). The vacuum cover at one end of the heat transfer tube to be detected (201) is connected to the pressure stabilization module (1), and the vacuum cover at the other end is connected to the water storage module (3). A2: Start the pressure stabilization module (1) to establish the vacuum degree inside the heat transfer tube to be detected (201). A3: Start the water storage module (3) to inject water into the heat transfer tube to be detected (201). A4: Observe whether there are bubbles through the vacuum cover at the connection with the pressure stabilization module (1). If there are bubbles, there is a leakage point (207). If there are no bubbles, there is no leakage point (207). The leak detection device for the shell-and-tube heat exchanger further comprises a calibration module (4), the calibration module (4) comprising a calibration circuit (403) and a calibration component (402). The calibration component (402) is connected to the vacuum cover connected to the water storage module (3) through the calibration circuit (403). A calibration control valve (401) is further arranged on the calibration circuit (403). The calibration component (402) is a standard leak hole component. When detecting for the first time, install the standard leak hole component at the calibration component (402), open the calibration control valve (401), the calibration circuit (403) is connected, air enters the heat transfer tube to be detected (201) through the standard leak hole component, and bubbles appear in the vacuum cover at one end of the heat transfer tube to be detected (201). Record the appearance time t1 of the bubbles at this time. The bubbles move in the heat transfer tube to be detected (201). When they move to the vacuum cover at the other end, record the appearance time t2 of the bubbles at this time. The reaction time of the bubbles in the heat transfer tube to be detected (201) is △t0 = t2 - t1. The movement speed s of the bubbles in the heat transfer tube to be detected (201) = the length of the heat transfer tube to be detected (201) / △t0. When detecting the heat transfer tube to be detected (201), if bubbles appear and the time difference between adjacent bubbles is T, then the distance between the leakage point and the vacuum cover connected to the pressure stabilization module (1) is the time difference T of adjacent bubbles * the movement speed s of the bubbles.

2. The leak detection method of the shell-and-tube heat exchanger according to claim 1, characterized in that: The voltage stabilizing module (1) includes an air extraction component (101), a gas-liquid separation component (102), and a pressure monitoring component (103). The gas-liquid separation component (102) is connected to the air extraction component (101) and the pressure monitoring component (103) through air ducts. The gas-liquid separation component (102) is connected to a vacuum hood at one end of the heat transfer tube (201) to be detected through an air extraction pipeline (204).

3. The leak detection method of the shell-and-tube heat exchanger according to claim 2, characterized in that: A branch pipe is further provided on the air duct between the gas-liquid separation component (102) and the pressure monitoring component (103). The branch pipe is connected to the atmosphere and a pressure control valve (104) is provided on the branch pipe; the pressure in the gas-liquid separation component (102) is adjusted by adjusting the opening degree of the pressure control valve (104), and the pressure in the gas-liquid separation component (102) is restored after the detection of the heat transfer tube (201) to be detected is completed.

4. The leak detection method of the shell-and-tube heat exchanger according to claim 1, characterized in that: The water storage module (3) includes a water storage tank (301), a circulation pump (302), a flow controller (303), and a water injection circuit pipe (306). The water injection circuit pipe (306) connects the water storage tank (301) and a vacuum hood at one end of the detection module (2); a water injection control valve (304) is further provided on the water injection circuit pipe (306), and the circulation pump (302) is installed in the water storage tank (301); the circulation pump (302), the flow controller (303), and the water injection control valve (304) are sequentially provided on the water injection circuit pipe (306).

5. The leak detection method of the shell-and-tube heat exchanger according to claim 4, characterized in that: The water storage module (3) further includes a circulating water circuit pipe (307). The circulating water circuit pipe (307) connects the water storage tank (301) and the vacuum hood connected to the water injection circuit pipe (306), and a circulating water control valve (305) is further provided on the circulating water circuit pipe (307).

6. The leak detection method of the shell-and-tube heat exchanger according to claim 1, characterized in that: An air outlet (205) is provided on the vacuum hood connected to the voltage stabilizing module (1), and an inlet / outlet (206) is provided on the vacuum hood connected to the water storage module (3).

7. The leak detection method of the shell-and-tube heat exchanger according to claim 1, characterized in that: It further includes a calibration module (4). The calibration module (4) includes a calibration circuit (403) and a calibration component (402). The calibration component (402) is connected to the vacuum hood connected to the water storage module (3) through the calibration circuit (403); a calibration control valve (401) is further provided on the calibration circuit (403).

8. The leak detection method of the shell-and-tube heat exchanger according to claim 7, characterized in that: The calibration component (402) is a standard leak hole component.

9. The leak detection method of the shell-and-tube heat exchanger according to claim 1, wherein: A plurality of the vacuum hoods are hermetically connected to both ends of the heat transfer tube (201) to be detected.

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