Infrared detection system and method for heat leakage on complex metal surfaces

Abstract

This invention provides an infrared detection system and method for thermal leakage on complex metal surfaces, comprising: a high-temperature steam generating unit; and an infrared imaging unit including an infrared camera capable of capturing infrared image sequences of a test sample. The high-temperature steam generating unit sequentially injects high-temperature steam into the test sample to heat it, with different pressures in the sample during the two steam injections. During each steam injection, the infrared camera captures a sequence of infrared images of the test sample. The infrared detection system identifies leakage points in the test sample by performing differential analysis on the infrared image sequences from the two heating processes. This invention effectively eliminates interference from different emissivities on the surface of the test piece, achieving accurate and convenient detection of thermal leakage on complex metal surfaces.

Description

Technical Field

[0001] This invention relates to the field of infrared leak detection technology, and in particular to an infrared detection system and method for thermal leakage on complex metal surfaces. Background Technology

[0002] Leak detection is a crucial aspect of monitoring and operating valves, pressure vessels, and pipelines. Traditional methods of applying soap suds for leak detection are increasingly being replaced by emerging non-destructive leak detection technologies due to drawbacks such as the dangers associated with high-pressure gas leaks and the time-consuming nature of the process.

[0003] Currently, non-destructive leak detection mainly includes acoustic detection methods such as ultrasonic methods. Among them, ultrasonic methods use ultrasonic waves outside the range of hearing frequency for detection, which does not require destroying the test sample and has the advantages of fast detection speed, safety, and no radiation. However, these detection methods also have obvious disadvantages, such as environmental noise strongly affecting the sample test results, thus greatly limiting their application scope.

[0004] In addition, non-destructive leak detection technology based on infrared thermography has been widely explored. However, the most common application of infrared thermography at present is only the tiling measurement of temperature on a two-dimensional plane. This measurement method is only the most basic application of infrared thermography, and due to the limitations of the working principle of thermal imagers, its application is very limited, especially for complex surfaces where the emissivity distribution is not uniform. Therefore, the plane temperature obtained when using this method for detection contains many abnormal points.

[0005] In the field of non-destructive leak detection of materials, the most mature infrared thermography techniques are pulse thermography and modulated thermography. The essence of these techniques is to obtain the thermal response of the surface under two different heating methods and then use subsequent image processing, such as phase mapping, to obtain the defects in the material. However, these methods require the material surface to be coated with black paint to obtain a relatively uniform emissivity on the specimen surface.

[0006] However, for specimens with complex geometric structures and non-penetrating defects such as corrosion holes and castings on metal surfaces like valves, pressure vessels, and pipelines, studies have shown that applying black paint to complex surfaces not only affects the distribution of the black paint due to the non-planar geometry, but also increases factors that alter the shape of radiation. Therefore, applying black paint, a commonly used method in the field of infrared detection, is not a good choice in this case.

[0007] Currently, common detection technologies for leaks on metal surfaces are partly based on leak points on a uniform material surface, meaning that surface emissivity does not interfere with the leak; and partly based on leak detection for cold fluids, where cold fluids appear as cold spots on infrared thermograms, while interfering factors appear as hot spots, so there is no conflict.

[0008] Currently, research on infrared detection technology for thermal leakage on complex metal surfaces is very limited. This is primarily due to the significant limitations of infrared thermal imagers when dealing with metallic materials. More critically, infrared imagers cannot eliminate interference from varying emissivity on the surface of the specimen; non-penetrating holes and surface defects can create false leak points when detected by infrared imagers. While traditional methods exist for obtaining the emissivity of complex specimen surfaces, such as dual-band infrared methods for emissivity correction, these methods are overly complex and expensive. Furthermore, the emissivity correction for leakage processes is not entirely consistent with the measurement and correction of emissivity for simple object surfaces, thus limiting their widespread application. Alternatively, dual-reference, dual-background methods can be used to obtain the surface emissivity, but since complex metal surfaces are non-Lambertian, even small deviations in emissivity can directly cause significant differences in displayed temperature, posing significant difficulties for emissivity calculation and hindering its engineering applications. Therefore, providing an infrared detection system and method capable of accurately and conveniently detecting thermal leakage on complex metal surfaces is a pressing technical problem that needs to be solved by those skilled in the art. Summary of the Invention

[0009] This invention designs an infrared detection system and method for heat leakage on complex metal surfaces, so as to achieve accurate and convenient detection of heat leakage on complex metal surfaces.

[0010] To address the above problems, this invention discloses an infrared detection system for heat leakage on complex metal surfaces, comprising:

[0011] The high-temperature steam generating unit is capable of filling the test sample with high-temperature steam;

[0012] An infrared imaging unit, comprising an infrared camera capable of capturing a sequence of infrared images of a test sample;

[0013] During the infrared detection of heat leakage, the high-temperature steam generating unit fills the test sample with high-temperature steam twice to heat the test sample, and the pressure in the test sample is different during the two heating processes.

[0014] During the two fillings with high-temperature steam, the infrared camera captures infrared image sequences of the test sample. The infrared detection system identifies the leakage points of the test sample by performing difference analysis on the infrared image sequences captured by the infrared camera during the two heating processes.

[0015] Furthermore, the infrared detection system also includes:

[0016] The shut-off valve, the high-temperature steam generating unit, the test sample and the shut-off valve are arranged in sequence and connected by a pipeline;

[0017] During one of the processes of filling the test sample with high-temperature steam, the shut-off valve is opened, allowing the high-temperature steam that the high-temperature steam generating unit fills into the test sample to be discharged through the shut-off valve after flowing through the test sample, thereby adjusting the pressure in the test sample to a lower pressure value.

[0018] During another process of filling the test sample with high-temperature steam, the shut-off valve is closed, so that the high-temperature steam filled into the test sample by the high-temperature steam generating unit cannot be discharged through the shut-off valve after flowing through the test sample, and accumulates between the high-temperature steam generating unit, the test sample and the shut-off valve, thereby adjusting the pressure in the test sample to a higher pressure value.

[0019] Furthermore, during the first injection of high-temperature steam into the test sample, the shut-off valve opens, and during the second injection of high-temperature steam into the test sample, the shut-off valve closes.

[0020] Furthermore, the infrared detection system also includes:

[0021] A cooling unit that can fill the test sample with a cooling medium and cool the test sample;

[0022] The cooling medium includes cooling water and / or cooling air.

[0023] Furthermore, the high-temperature steam generating unit includes:

[0024] A water storage tank and a steam boiler are provided. The water storage tank is connected to the steam boiler via a pipe, and the steam boiler is connected to the test sample via a pipe. Water in the water storage tank flows into the steam boiler and is heated to generate high-temperature steam. The high-temperature steam generated by the steam boiler is then injected into the test sample.

[0025] Furthermore, the high-temperature steam generating unit also includes:

[0026] A pressure gauge is installed on the pipe between the steam boiler and the test sample to detect the pipe pressure at its location.

[0027] A check valve, installed on the pipe between the steam boiler and the test sample, is used to prevent high-temperature steam from flowing back into the steam boiler.

[0028] A method for infrared detection of heat leakage on complex metal surfaces, wherein the infrared detection method employs an infrared detection system for heat leakage on complex metal surfaces for leakage detection, and the infrared detection method includes the following steps:

[0029] S1, high-temperature steam is injected into the test sample twice by a high-temperature steam generating unit to heat the test sample and obtain infrared image sequences of the test sample under different pressures; wherein, the infrared image sequence obtained during the first inflation and heating is recorded as the first infrared image sequence, and the infrared image sequence obtained during the second inflation and heating is recorded as the second infrared image sequence.

[0030] S2, select the temperature of a flat surface area of ​​the test sample in one frame of the first infrared image sequence as the first reference temperature T. flat-ref ;

[0031] S3, Obtain the temperature of the corresponding region in one frame of the second infrared image sequence as the second reference temperature T. flat ;

[0032] S4, compared to the first reference temperature T flat-ref Second reference temperature T flat The relative size, if |T flat -T flat-ref If |≤ preset value △T, then the first reference temperature T flat-ref Second reference temperature T flat Match successful, continue to step S5; if |T flat -T flat-ref |>Preset value △T, then the first reference temperature T flat-ref Second reference temperature T flat If the matching fails, repeat step S3 to obtain the second reference temperature T again using a different infrared image. flat Then, the first reference temperature T is re-established. flat-ref Second reference temperature T flat The matching continues until a match is found.

[0033] S5, the first reference temperature T flat-ref The corresponding infrared image and the second reference temperature T flat The corresponding infrared images form an image pair;

[0034] S6, perform a difference analysis on the two infrared images in the image pair obtained in step S5, and calculate the temperature difference ΔT between each region in the two infrared images. r1 , where △T r1 =|T r -T ref-r |, the T ref-r The T represents the temperature values ​​of each region in the infrared images from the first infrared image sequence; r These are the temperature values ​​of each region in the infrared images from the second infrared image sequence;

[0035] S7, based on the temperature difference △T r1 The size of the point of thermal leakage on the complex metal surface is determined.

[0036] Furthermore, step S7 includes:

[0037] Determine the temperature difference ΔT r1 If the temperature is greater than 3°C, the area is considered a leak point; otherwise, the area is considered to be free of leaks.

[0038] Furthermore, step S7 includes:

[0039] After step S6, steps S2 to S6 are repeated. n different pairs of infrared images are selected to form image pairs, and the temperature difference value of each region in each image pair is calculated. Then, the average of the n temperature differences of each region is taken as the final temperature difference value ΔT of that region. r2 And based on the final temperature difference ΔT r2 The magnitude of the value determines the heat leakage point on the complex metal surface, where n≥2.

[0040] Furthermore, step S7 includes:

[0041] After step S6, repeat steps S2 to S6, selecting n different pairs of infrared images to form image pairs, and calculating the temperature difference ΔT in each region of each image pair. r3 Then, according to the temperature difference ΔT r3 The size of the leak point is used to make a preliminary determination.

[0042] The preliminary judgment results were then investigated, and only when all temperature differences ΔT in a certain area were considered... r3 Only when all indications point to the area as a heat leak point is the area considered the final heat leak point.

[0043] Furthermore, step S1 includes:

[0044] S11, First inflation and heating: Adjust the position of the infrared camera so that it faces the test area in the test sample. Then, water from the water tank is pumped to the steam boiler. Set the temperature and flow rate of the high-temperature steam output from the steam boiler. Inject high-temperature steam into the test sample through the steam boiler to heat the test sample. At the same time, measure the pressure P1 in the test sample and capture the infrared image sequence of the test sample using the infrared camera to obtain the first infrared image sequence. At this time, the shut-off valve is open, and the high-temperature steam generated by the steam boiler can be discharged through the shut-off valve after flowing through the test sample.

[0045] S12, Initial cooling: Water in the water storage tank is used as cooling water and introduced into the test sample through the cooling water delivery pipe to perform initial cooling on the test sample;

[0046] S13, Re-cooling: External air is introduced into the test sample through a cooling air delivery pipe by a fan to re-cool the test sample and remove the cooling water remaining in the infrared detection system at the same time.

[0047] S14, Second inflation heating: Adjust the infrared detection system to the state of the first inflation heating, but close the shut-off valve, capture the second infrared image sequence, and record the pressure in the test sample during the second inflation heating as P2, then P2 > P1. The infrared detection system and method for thermal leakage on complex metal surfaces described in this application uses the high-temperature steam generating unit to inject high-temperature steam into the test sample twice to heat the test sample, and the pressure in the test sample is different during the two high-temperature steam heating processes; then, by performing difference analysis on the infrared image sequences of the test sample during the two heating processes, the leakage point of the test sample can be identified, which can effectively eliminate the interference of different emissivity on the surface of the test piece, and realize accurate and convenient detection of thermal leakage on complex metal surfaces. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the structure of the infrared detection system for heat leakage on complex metal surfaces described in this invention;

[0049] Figure 2 These are photographs of the test samples used in the embodiments of the present invention;

[0050] Figure 3 The infrared images of the test samples used in the embodiments of the present invention were obtained using conventional methods.

[0051] Figure 4 Infrared images of the test samples used in the embodiments of the present invention obtained during the first inflation and heating process;

[0052] Figure 5 Infrared images of the test sample used in the embodiments of the present invention obtained during the second inflation and heating process;

[0053] Figure 6 This is a photograph of the operation interface used in this invention to compare infrared image sequences obtained from two inflation and heating processes.

[0054] Figure 7 Infrared photographs obtained by processing different image pairs.

[0055] Explanation of reference numerals in the attached diagram: 1. Fan; 2. Water tank; 3. First control valve; 4. Water pump; 5. Pressure gauge; 6. Check valve; 7. Steam boiler; 8. Test sample; 9. Circular slide rail; 10. Water tank; 11. Discharge pipe; 12. Vertical slide rail; 13. Infrared camera; 14. Fixed platform; 15. Shut-off valve; 16. Second control valve; 17. Third control valve; 18. Fourth control valve; 19. Fifth control valve; 20. Sixth control valve. Detailed Implementation

[0056] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0057] Example 1

[0058] like Figures 1-7 As shown, a complex metal surface heat leakage infrared detection system includes:

[0059] The high-temperature steam generating unit is capable of filling the test sample 8 with high-temperature steam;

[0060] An infrared camera unit includes an infrared camera 13, which is capable of capturing infrared sequence images of the test sample 8.

[0061] During the infrared detection of heat leakage, the high-temperature steam generating unit fills the test sample 8 with high-temperature steam twice to heat the test sample 8, and the pressure in the test sample 8 is different during the two fillings of high-temperature steam for heating.

[0062] During the two fillings with high-temperature steam, the infrared camera 13 captures infrared image sequences of the test sample 8. The infrared detection system identifies the leakage points of the test sample 8 by performing difference analysis on the infrared image sequences captured by the infrared camera 13 during the two heating processes.

[0063] Furthermore, in this application, when the test sample 8 is heated by high-temperature steam for the first time, the pressure in the test sample 8 is recorded as P1; when the test sample 8 is heated by high-temperature steam for the second time, the pressure in the test sample 8 is recorded as P2. In implementing this application, the key is to obtain the thermal leakage state of the test sample 8 under two different pressures. Therefore, when using the infrared detection system described in this application for testing, the relative magnitudes of P1 and P2 can be set as P1 > P2, or P1 < P2.

[0064] Preferably, the relative sizes of P1 and P2 are set to P1 < P2.

[0065] For the purpose of clearly and concisely explaining this application, the following explanation is based on P1 < P2. When the relative size of P1 and P2 is set to P1 > P2, only the corresponding parameters and calculation process need to be changed, and this application will not repeat the details.

[0066] Furthermore, the infrared detection system also includes:

[0067] The shut-off valve 15 is arranged in sequence with the high-temperature steam generating unit, the test sample 8 and the shut-off valve 15 connected by a pipeline.

[0068] During one of the processes of filling the test sample 8 with high-temperature steam, the shut-off valve 15 is opened, so that the high-temperature steam filled into the test sample 8 by the high-temperature steam generating unit can be discharged through the shut-off valve 15 after flowing through the test sample 8, thereby adjusting the pressure in the test sample 8 to a lower pressure value P1.

[0069] During another process of filling the test sample 8 with high-temperature steam, the shut-off valve 15 is closed, so that the high-temperature steam filled into the test sample 8 by the high-temperature steam generating unit cannot be discharged through the shut-off valve 15 after flowing through the test sample 8, and accumulates between the high-temperature steam generating unit, the test sample 8 and the shut-off valve 15, thereby adjusting the pressure in the test sample 8 to a higher pressure value P2.

[0070] Preferably, the shut-off valve 15 is opened during the first filling of the test sample 8 with high-temperature steam, and closed during the second filling of the test sample 8 with high-temperature steam.

[0071] Furthermore, the infrared detection system also includes:

[0072] The cooling unit is capable of filling the test sample 8 with a cooling medium and cooling the test sample 8.

[0073] Furthermore, the high-temperature steam generating unit includes:

[0074] The water storage tank 2 and the steam boiler 7 are connected by a pipe. The steam boiler 7 is connected to the test sample 8 by a pipe. Water in the water storage tank 2 flows into the steam boiler 7 and is heated to generate high-temperature steam. The high-temperature steam generated by the steam boiler 7 is then injected into the test sample 8.

[0075] Furthermore, the high-temperature steam generating unit also includes:

[0076] Water pump 4 is disposed between the water storage tank 2 and the steam boiler 7, and the water pump 4 is used to pump water from the water storage tank 2 to the steam boiler 7.

[0077] Furthermore, the high-temperature steam generating unit also includes:

[0078] Pressure gauge 5, which is installed on the pipe between the steam boiler 7 and the test sample 8, is used to detect the pipe pressure at its location;

[0079] Check valve 6, which is installed on the pipe between the steam boiler 7 and the test sample 8, is used to prevent high-temperature steam from flowing back into the steam boiler 7.

[0080] Preferably, the check valve 6 is disposed between the steam boiler 7 and the pressure gauge 5.

[0081] Furthermore, the high-temperature steam generating unit also includes multiple control valves, specifically as follows:

[0082] The first control valve 3 is located between the water storage tank 2 and the water pump 4 and is used to control the discharge of water from the water storage tank 2.

[0083] The third control valve 17 is located between the steam boiler 7 and the test sample 8 and is used to control the discharge of high-temperature steam from the steam boiler 7.

[0084] Preferably, the third control valve 17 is disposed between the steam boiler 7 and the check valve 6.

[0085] Furthermore, the infrared camera unit also includes:

[0086] Fixed platform 14,

[0087] The annular slide rail 9 is a horizontally arranged annular track located on the fixed platform 14.

[0088] A vertical slide rail 12 is a track arranged in a vertical direction. The vertical slide rail 12 is arranged on the annular slide rail 9 and can slide along the annular slide rail 9.

[0089] The infrared camera 13 is mounted on the vertical slide rail 12, and the infrared camera 13 can slide up and down along the vertical slide rail 12;

[0090] In use, the height of the infrared camera 13 can be adjusted by sliding it up and down along the vertical slide rail 12; the position of the infrared camera 13 in the horizontal plane can be adjusted by sliding it along the annular slide rail 9, so that the infrared camera 13 is positioned directly facing the test sample 8 or directly facing the area to be detected in the test sample 8.

[0091] As some embodiments of this application, the infrared camera unit can automatically adjust the position of the infrared camera 13 by manually adjusting the position of the infrared camera 13, or by driving the infrared camera 13 and the vertical slide rail 12 to move by a motor or the like.

[0092] Preferably, in this application, the position and shooting parameters of the infrared camera 13 can be automatically adjusted by software installed on a terminal such as a mobile phone or computer.

[0093] Furthermore, the cooling medium used by the cooling unit includes cooling water and / or cooling air.

[0094] Furthermore, the cooling unit includes:

[0095] The cooling water delivery pipe is connected at both ends to the water storage tank 2 and the test sample 8, respectively. The water in the water storage tank 2 can be delivered to the test sample 8 as cooling water through the cooling water delivery pipe.

[0096] Furthermore, the cooling unit includes:

[0097] Fan 1,

[0098] The cooling air delivery pipe is connected at both ends to the fan 1 and the test sample 8, respectively. The fan 1 and the cooling air delivery pipe can deliver atmospheric air as cooling air to the test sample 8.

[0099] Preferably, the cooling medium used in the cooling unit includes cooling water and cooling air. When using the infrared detection system, cooling water should be introduced into the test sample 8 for initial cooling first, and then cooling air should be introduced into the test sample 8 for further cooling, while removing the residual cooling water in the infrared detection system.

[0100] Furthermore, the cooling unit also includes:

[0101] The fourth control valve 18 is installed on the cooling water delivery pipeline, and the opening and closing of the cooling water delivery pipeline can be controlled by the fourth control valve 18.

[0102] A fifth control valve 19 is provided on the cooling air delivery pipe. Preferably, the fifth control valve 19 is located near the air outlet of the fan 1. The fifth control valve 19 can control the opening and closing of the cooling air delivery pipe.

[0103] Furthermore, the infrared detection system also includes:

[0104] The sixth control valve 20 is located between the water storage tank 2 and the water pump 4 to prevent cooling water from entering the water pump 4 when the cooling water delivery pipeline is delivering cooling water.

[0105] The second control valve 16 is located between the pressure gauge 5 and the test sample 8 and is used to control whether fluid can enter the test sample 8.

[0106] Furthermore, as some embodiments of this application, the infrared detection system further includes:

[0107] Water tank 10, which is an open container at the top, and the outlet of the shut-off valve 15 is suspended above the water tank 10 through a pipe, so that the fluid discharged from the outlet of the shut-off valve 15, whether it is gas or liquid, can be discharged through the outlet of the shut-off valve 15.

[0108] The discharge pipe 11 is connected to the outlet of the water tank 10 and is used to discharge the water in the water tank 10 into a selected container or pipe.

[0109] As some other embodiments of this application, the infrared detection system further includes:

[0110] Water tank 10, which is a closed container, and the outlet of the shut-off valve 15 is inserted into the water tank 10 through a pipe, so that the fluid discharged from the outlet of the shut-off valve 15 can be discharged into the water tank 10 through the outlet of the shut-off valve 15.

[0111] The discharge pipe 11 is connected to the outlet of the water tank 10 and is used to discharge the fluid in the water tank 10 into a selected container or pipe.

[0112] Example 2

[0113] like Figures 1-7 As shown, this application also provides an infrared detection method for heat leakage on complex metal surfaces, including the following steps:

[0114] S1, high-temperature steam is injected into the test sample 8 twice by a high-temperature steam generating unit to heat the test sample 8 and obtain infrared image sequences of the test sample 8 under different pressures; wherein, the infrared image sequence obtained during the first inflation and heating is recorded as the first infrared image sequence, and the infrared image sequence obtained during the second inflation and heating is recorded as the second infrared image sequence.

[0115] S2, select the temperature of a flat surface area of ​​the test sample 8 in one frame of the first infrared image sequence as the first reference temperature T. flat-ref ;

[0116] S3, Obtain the temperature of the corresponding region in one frame of the second infrared image sequence as the second reference temperature T. flat ;

[0117] S4, compared to the first reference temperature T flat-ref Second reference temperature T flat The relative size, if |T flat -T flat-ref If |≤ preset value △T, then the first reference temperature T flat-ref Second reference temperature T flat Match successful, continue to step S5; if |T flat -T flat-ref |>Preset value △T, then the first reference temperature T flat-ref Second reference temperature T flat If the matching fails, repeat step S3 to obtain the second reference temperature T again using a different infrared image. flat Then, the first reference temperature T is re-established. flat-ref Second reference temperature T flat The matching continues until a match is found.

[0118] S5, the first reference temperature T flat-ref The corresponding infrared image and the second reference temperature T flat The corresponding infrared images form an image pair;

[0119] S6, perform a difference analysis on the two infrared images in the image pair obtained in step S5, and calculate the temperature difference ΔT between each region in the two infrared images. r1 , where △T r1 =|T r -T ref-r |, the T ref-r The T represents the temperature values ​​of each region in the infrared images from the first infrared image sequence; r These are the temperature values ​​of each region in the infrared images from the second infrared image sequence;

[0120] S7, based on the temperature difference △T r1 The size of the point of thermal leakage on the complex metal surface is determined.

[0121] In step S4, when |T flat -T flat-ref |>Preset value △T, replace with another frame of infrared image and reacquire the second reference temperature T flat At this time, only the selected infrared image in the second infrared image sequence needs to be replaced, but the selected surface area does not need to be replaced. This needs to be done at the first reference temperature T. flat-ref The corresponding region obtains a second reference temperature T flat .

[0122] Furthermore, in step S6, when the pressure value P1 in the test sample 8 during the first inflation and heating is less than the pressure value P2 in the test sample 8 during the second inflation and heating, the temperature difference ΔT r1 =T r -T ref-r ; where T r T represents the temperature value of each region in the infrared image from the second infrared image sequence in the image pair; ref-r The temperature value of each region in the infrared image from the first infrared image sequence in the image pair.

[0123] Conversely, when P2 < P1, the temperature difference ΔT r1 =T ref-r -T r .

[0124] In this application, P1 < P2, and the temperature difference ΔT is defined as follows: r1 =T r -T ref-r The infrared detection method described in this application will be illustrated using an example.

[0125] Furthermore, step S7 includes:

[0126] Determine the temperature difference ΔT r1 If the temperature is greater than 3°C, the area is considered a leak point; otherwise, the area is considered to be free of leaks.

[0127] As in some other embodiments of this application, step S7 includes:

[0128] After step S6, steps S2 to S6 are repeated. n different pairs of infrared images are selected to form image pairs, and the temperature difference value of each region in each image pair is calculated. Then, the average of the n temperature differences of each region is taken as the final temperature difference value ΔT of that region. r2And based on the final temperature difference ΔT r2 If the temperature is greater than 3°C, the area is determined to be a leak point; otherwise, the area is determined to be without leakage, thus identifying the thermal leak point on the complex metal surface, where n≥2.

[0129] As in some other embodiments of this application, step S7 includes:

[0130] After step S6, repeat steps S2 to S6, selecting n different pairs of infrared images to form image pairs, and calculating the temperature difference ΔT in each region of each image pair. r3 Then, according to the temperature difference ΔT r3 The size of the leak point is used to make a preliminary determination.

[0131] The preliminary judgment results were then investigated, and only when all temperature differences ΔT in a certain area were considered... r3 Only when all temperatures are greater than 3°C, indicating that the area is a heat leak point, is the area considered the final heat leak point.

[0132] Furthermore, step S1 includes:

[0133] S11, First inflation and heating: Adjust the position of the infrared camera 13 so that it faces the test area in the test sample 8. Then, open the first control valve 3, the sixth control valve 20, the third control valve 17, the second control valve 16, and the shut-off valve 15. Turn on the water pump 4 and the steam boiler 7. The water pump 4 transports water from the water tank 2 to the steam boiler 7. Set the temperature and flow rate of the high-temperature steam output by the steam boiler 7. Inject high-temperature steam into the test sample 8 through the steam boiler 7 to heat the test sample 8. At the same time, obtain the pressure in the infrared system through the pressure gauge 5, especially measure the pressure P1 in the test sample 8. Take an infrared image sequence of the test sample 8 through the infrared camera 13 to obtain the first infrared image sequence. At this time, since the shut-off valve 15 is open, the high-temperature steam generated by the steam boiler 7 can be discharged through the shut-off valve 15 after flowing through the test sample 8.

[0134] S12, Initial cooling: Close the sixth control valve 20 and open the fourth control valve 18. The water in the water storage tank 2 is used as cooling water and enters the test sample 8 through the cooling water delivery pipe to perform initial cooling on the test sample 8.

[0135] S13, Cooling again: Close the first control valve 3 and the fourth control valve 18, open the fifth control valve 19, start the fan 1, and introduce external air into the test sample 8 through the cooling air delivery pipe to cool the test sample 8 again, while removing the residual cooling water in the infrared detection system.

[0136] S14, Second inflation heating: Adjust the infrared detection system to the state of the first inflation heating, but close the shut-off valve 15. The temperature and flow rate of the high-temperature steam output by the steam boiler 7 remain unchanged, i.e., the internal pressure of the boiler remains unchanged. Take the second infrared image sequence. When taking the second infrared image sequence, record the pressure in the test sample during the second inflation heating as P2. The pressure in the test sample 8 is P2 > P1. At the same time, the temperature T of the flat area on the surface of the test sample 8 is... flat Able to maintain the temperature T of the flat area on the surface of the test sample 8 during the first inflation and heating process. flat-ref A value close to, preferably, when capturing the first infrared image sequence and the second infrared image sequence, is |T flat -T flat-ref |≤ preset value △T, where the preset value △T here is the same as the preset value △T in the aforementioned step S4.

[0137] Furthermore, in step S4, the preset value △T = 3℃.

[0138] As some embodiments of this application, the infrared detection system and infrared detection method can be applied to detect thermal leaks in samples such as defective valves, pressure vessels, and metal pipes.

[0139] Furthermore, regarding the test sample 8, according to existing infrared thermal imaging technology:

[0140] I(T r =ε(T)I(T)+[1-ε(T)]I(T) u );

[0141] I(T ref-r )=ε(T ref )I(T ref )+[1-ε(T ref )]I(T u );

[0142] Meanwhile, T can be directly calculated using the built-in program of the thermal imager. r , and T ref-r ;

[0143] Wherein, ε(T) and ε(T) refI(T) and I(T) represent the emissivity of the metal during the second and first gas-filling heating processes, respectively; ref The terms I(T) represent the radiation intensity of the metal during the second inflation heating and the first inflation heating, respectively; u The I(T) represents the radiation intensity corresponding to the environmental reflection during the second inflation heating and the first inflation heating; r ) and I(T ref-r The value represents the surface radiation intensity after considering the overall effect of the actual surface temperature and ambient temperature during the second inflation heating and the first inflation heating.

[0144] The working principle of the infrared detection system and infrared detection method described in this application is described below:

[0145] First, during the two inflation and heating processes, the radiation intensity I(T) in infrared thermography... r The calculation formula is as follows:

[0146] I(T r =ε(T)I(T)+[1-ε(T)]I(T) u );

[0147] Where T is the surface temperature of the test sample, which can be further subdivided according to the selected location:

[0148] Surface temperature at the smoothest part of the surface, T flat ;

[0149] Surface temperature at the pseudo-leak point, T pseudo ;

[0150] Surface temperature at the actual leak point, T true ;T r The surface radiation temperature taking into account the overall effect of the actual surface temperature and the ambient temperature;

[0151] ε(T) is the emissivity at that temperature;

[0152] I(T) is the radiation intensity corresponding to this temperature;

[0153] T u Ambient temperature;

[0154] At the radiation intensity I(T) r In the calculation formula, when the measurement distance is sufficiently short, the air absorption rate can be ignored. To simplify the problem, assume the ambient temperature is T. u The surface of the test sample is consistently affected, and the overall surface emissivity of the test sample is set to 1. Therefore, the measurement process is mainly based on the surface radiation temperature T of the test sample. rAt the same time, the radiation I(T) corresponding to the environmental reflection effect. u It can be considered as part of surface radiation.

[0155] During the first inflation and heating process, the shut-off valve 15 at the end of test sample 8 opens; during the second inflation and heating process, the shut-off valve 15 at the end of test sample 8 closes, leaving test sample 8 in a state similar to "pressure buildup." Therefore, it is obvious that test sample 8, with the same leakage opening, will leak more water vapor during the second inflation and heating process, resulting in more water vapor condensation. This causes the temperature at the actual leakage point to differ between the two heating processes, while the temperatures of other surfaces in test sample 8 remain largely consistent. Therefore, this application uses the temperature of a smooth surface as the reference temperature T during the first heating process. flat-ref During the second heating process, the temperature T is marked at the same location. flat Therefore, the basis for image processing is: T flat-ref ≈T flat .

[0156] Therefore, before performing infrared image sequence processing, the first reference temperature T is first determined. flat-ref Second reference temperature T flat The size of the infrared image sequences obtained from the two inflation processes are compared and combined to form image pairs.

[0157] Then, when calculating the difference in radiation intensity in each region of the two infrared images in the image pair:

[0158] For the smooth surface of test sample 8, the radiation intensity I(T) at the smooth surface of test sample 8 during the second heating process is as follows: flat-r )=ε(T flat )I(T flat )+[1-ε(T flat )]I(T u );

[0159] And, the radiation intensity I(T) at the smooth surface of sample 8 during the first heating process was tested. flat-ref-r )=ε(T flat-ref )I(T flat-ref )+[1-ε(T flat-ref )]I(T u );

[0160] The emissivity of smooth-surfaced metals is very low, around 0.2.

[0161] Simultaneously, ε(T) flat )I(T flat )≈ε(T flat-ref )I(T flat-ref );

[0162] [1-ε(T flat )]I(T u )≈[1-ε(T flat-ref )]I(T u );

[0163] At this point, subtracting the image of the flat portion of the test sample 8 yields:

[0164] I(T flat-r )-I(T flat-ref-r )≈0;

[0165] Similarly, for the spurious leak point in test sample 8, the radiation intensity I(T) at the spurious leak point on the surface of test sample 8 during the second heating process is as follows: pseudo-r )=ε(T pseudo )I(T pseudo )+[1-ε(T pseudo )]I(T u );

[0166] In addition, the radiation intensity I(T) at the pseudo-leakage point on the surface of sample 8 during the first heating process was tested. pseudo-ref-r )=ε(T pseudo-ref )I(T pseudo-ref )+[1-ε(T pseudo-ref )]I(T u );

[0167] Since the emissivity at the spurious leak point is high, close to 1, then:

[0168] ε(T pseudo )I(T pseudo ) >> [1-ε(T pseudo )]I(T u );

[0169] ε(T pseudo-ref )I(T pseudo-ref ) >> [1-ε(T pseudo-ref )]I(T u This means that the radiation corresponding to the environmental reflection in this area can be ignored, and similar to the flat section, due to the pseudo-leakage point T during the first heating process... pseudo-ref The pseudo-leak point T during the second heating process pseudo Similar, therefore,

[0170] ε(T pseudo )I(T pseudo )≈ε(T pseudo-ref )I(T pseudo-ref );

[0171] After subtracting the images, we get:

[0172] I(T pseudo-r )-I(T pseudo-ref-r )≈0;

[0173] In this way, false leak points can also be eliminated.

[0174] Based on this, for the actual leak point in test sample 8, the radiation intensity I(T) at the actual leak point on the surface of test sample 8 was tested during the second heating process. true-r )=ε(T true )I(T true )+[1-ε(T true )]I(T u );

[0175] In addition, the radiation intensity I(T) at the actual leakage point on the surface of sample 8 during the first heating process was tested. true-ref-r )=ε(T true-ref )I(T true-ref )+[1-ε(T true-ref )]I(T u );

[0176] Since the emissivity at the actual leak point is high, close to 1, then:

[0177] ε(T true )I(T true ) >> [1-ε(T true )]I(T u );

[0178] ε(T true-ref )I(T true-ref ) >> [1-ε(T true-ref )]I(T u This means that the radiation corresponding to the environmental reflection in this area can also be ignored.

[0179] However, at the actual leak point in test sample 8, due to steam condensation, a positive temperature gradient will occur during the two inflation heating processes. That is, the temperature at the actual leak point in test sample 8 during the second inflation heating process will be significantly higher than during the first inflation heating process. Simultaneously, because the leakage amount at the actual leak point differs between the two inflation heating processes, both the temperature and radiation at the actual leak point will show significant differences. At this point:

[0180] T true >T true-ref ;

[0181] ε(T true)≥ε(T true-ref );

[0182] According to I(T) true-r )-I(T true-ref-r After subtracting the image radiation intensity of this region, I(T) true-r )-I(T true-ref-r If ) > 0, the corresponding temperature difference ΔT in the infrared image r1 =T true-r -T true-ref-r If the temperature is >3℃, then the actual leakage point of test sample 8 can be obtained.

[0183] Thus, the temperature difference ΔT after subtracting the images can be used as a basis for calculation. r1 This is used to eliminate false leak points, reveal the real leak points, and determine whether each area is a real leak point.

[0184] Example 3

[0185] The following describes the processing procedure and results of the infrared detection system and method described in this application through actual testing of physical objects:

[0186] Select Appendix Figure 2 The valve shown was used as a test sample for actual testing. It can be seen that, in the attached... Figure 2 The test sample displayed has areas wrapped with PTFE tape and black paint as spurious leak points. Meanwhile, the actual leak point is the leak point where the internal ball valve's controllable opening is located. Infrared images captured by infrared camera 13 are shown below. Figure 3 As shown, in Figure 3 As can be seen, the area where the raw material tape is wrapped and the black paint spots form a false leakage area, interfering with the detection results. After performing the infrared detection method according to steps S1~S7, a first infrared image sequence and a second infrared image sequence are obtained. Then, infrared image analysis software is used to compare the two infrared images in the image pair, and two infrared images that meet the conditions are selected to form an image pair. One image pair is as follows: Figure 4 and Figure 5 As shown, then as Figure 6 As shown, the two infrared images that make up the image pair are compared, and the temperature difference ΔT in each region of the two infrared images is calculated. r1 And based on the temperature difference ΔT r1 The size of the heat leak point on the complex metal surface is determined, and the results are as follows: Figure 7 As shown in a, b, and c, where, Figure 7 'a' is T flat = 38.3℃, Figure 7 b is T flat = 40.6℃, Figure 7 c is T flat = 44℃, at the same time, Figure 7 The three pictures T flat-ref Both are 41℃. The calculated temperature difference ΔT at the leakage point in Figure a is: r1 =13.1K, the temperature difference ΔT at the leak point in Figure b is 13.1K. r1 =13.3K, the temperature difference ΔT at the leak point in Figure c is 13.3K. r1 =14.1K, which is much larger than the temperature difference ΔT in other regions. r1 .

[0187] This indicates that the same image from the first heating process was selected as a reference. T flat-ref =41℃), select different images of the second heating process ( T flat = 38.3℃, T flat = 40.6℃, T flat The leak point could be successfully located at temperatures of 44℃, and when T flat - T flat-ref When the absolute value of the difference is ≤3℃, the influence of interfering factors can be effectively eliminated.

[0188] In addition, traditional methods were used to perform infrared thermal leakage detection on the test samples. The test process was similar to the first inflation and heating process described in this application, and will not be repeated here.

[0189] Comparing the above figures, it can be seen that different image pairs were selected in Figure 9, namely the second reference temperature T. flat and the first reference temperature T flat-ref Even when there is a certain deviation between the two, leak point detection can still yield good test results.

[0190] Therefore, it can be seen that the infrared detection system and method for thermal leakage of complex metal surfaces described in this application combines the infrared image sequences of two different gas-filling and heating processes into an image pair. After difference calculation and analysis, the leakage point located eliminates the interference of false leakage points caused by different structures of the metal surface, avoids the process of reverse calculation of the metal surface emissivity, and can more intuitively and quickly locate the leakage point. It can be promoted and used in engineering.

[0191] In summary, the infrared detection system and method for thermal leakage on complex metal surfaces described in this application are based on the comparison of temperature gradients during highly transient processes on complex metal surfaces. During detection, a shut-off valve is installed at the end of the test sample, and the same heating steam parameters, including temperature and flow rate, are provided to achieve unsteady-state heating of the test sample: a process of primary heating (shut-off valve open) - cooling (shut-off valve open) - secondary heating (shut-off valve closed). Infrared image sequences of leakage from the test sample are obtained under the conditions of the shut-off valve being open and closed, and during the two heating processes. Precise spatial positioning is achieved by controlling the infrared camera with high-precision ring and vertical slide rails. Computer software is used to pair and subtract the infrared image sequences according to the reference temperature of the test sample wall, and combined with experiments, the actual temperature difference range of the leakage is given, successfully achieving leakage detection and location. This can eliminate the influence of uneven metal surface emissivity on the detection results. Although the invention has been disclosed above, it is not limited thereto. In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. An infrared detection system for heat leakage on complex metal surfaces, characterized in that, include: A high-temperature steam generating unit is capable of filling the test sample (8) with high-temperature steam; An infrared camera unit includes an infrared camera (13) capable of capturing infrared sequence images of the test sample (8); During the infrared detection of heat leakage, the high-temperature steam generating unit fills the test sample (8) with high-temperature steam twice to heat the test sample (8), and the pressure in the test sample (8) is different when the high-temperature steam is filled and heated twice. During the two fillings of high-temperature steam, the infrared camera (13) captures the infrared image sequence of the test sample (8) respectively. The infrared detection system identifies the leakage point of the test sample (8) by performing difference analysis on the infrared image sequence captured by the infrared camera (13) during the two heating processes. The aforementioned infrared detection system for thermal leakage on complex metal surfaces employs the following infrared detection method for thermal leakage on complex metal surfaces, the infrared detection method comprising the following steps: S1, high-temperature steam is injected into the test sample twice by a high-temperature steam generating unit to heat the test sample and obtain infrared image sequences of the test sample under different pressures; wherein, the infrared image sequence obtained during the first inflation and heating is recorded as the first infrared image sequence, and the infrared image sequence obtained during the second inflation and heating is recorded as the second infrared image sequence. S2, select the temperature of a flat surface area of ​​the test sample in one frame of the first infrared image sequence as the first reference temperature T. flat-ref ; S3, Obtain the temperature of the corresponding region in one frame of the second infrared image sequence as the second reference temperature T. flat ; S4, compared to the first reference temperature T flat-ref Second reference temperature T flat The relative size, if |T flat -T flat-ref If |≤ preset value △T, then the first reference temperature T flat-ref Second reference temperature T flat Match successful, continue to step S5; if |T flat -T flat-ref |>Preset value △T, then the first reference temperature T flat-ref Second reference temperature T flat If the matching fails, repeat step S3 to obtain the second reference temperature T again using a different infrared image. flat Then, the first reference temperature T is re-established. flat-ref Second reference temperature T flat The matching continues until a match is found. S5, the first reference temperature T flat-ref The corresponding infrared image and the second reference temperature T flat The corresponding infrared images form an image pair; S6, perform a difference analysis on the two infrared images in the image pair obtained in step S5, and calculate the temperature difference ΔT between each region in the two infrared images. r1 , where △T r1 =|T r -T ref-r |, the T ref-r The T represents the temperature values ​​of each region in the infrared images from the first infrared image sequence; r These are the temperature values ​​of each region in the infrared images from the second infrared image sequence; S7, based on the temperature difference △T r1 The size of the point of thermal leakage on the complex metal surface is determined.

2. The infrared detection system according to claim 1, characterized in that, The infrared detection system also includes: The high-temperature steam generating unit, the test sample (8), and the shut-off valve (15) are arranged in sequence and connected by a pipeline; During one of the processes of filling the test sample (8) with high-temperature steam, the shut-off valve (15) is opened, so that the high-temperature steam filled into the test sample (8) by the high-temperature steam generating unit can be discharged through the shut-off valve (15) after flowing through the test sample (8), thereby adjusting the pressure in the test sample (8) to a lower pressure value. During another process of filling the test sample (8) with high-temperature steam, the shut-off valve (15) is closed, so that the high-temperature steam filled into the test sample (8) by the high-temperature steam generating unit cannot be discharged through the shut-off valve (15) after flowing through the test sample (8), and accumulates between the high-temperature steam generating unit, the test sample (8) and the shut-off valve (15), thereby adjusting the pressure in the test sample (8) to a higher pressure value.

3. The infrared detection system according to claim 2, characterized in that, During the first filling of the test sample (8) with high-temperature steam, the shut-off valve (15) is opened, and during the second filling of the test sample (8) with high-temperature steam, the shut-off valve (15) is closed.

4. The infrared detection system according to claim 1, characterized in that, The infrared detection system also includes: A cooling unit that can fill the test sample (8) with a cooling medium and cool the test sample (8); The cooling medium includes cooling water and / or cooling air.

5. The infrared detection system according to claim 1, characterized in that, The high-temperature steam generating unit includes: A water storage tank (2) and a steam boiler (7) are connected to the steam boiler (7) via a pipe. The steam boiler (7) is connected to the test sample (8) via a pipe. Water in the water storage tank (2) flows into the steam boiler (7) and is heated to generate high-temperature steam. The steam boiler (7) fills the test sample (8) with the generated high-temperature steam.

6. The infrared detection system according to claim 5, characterized in that, The high-temperature steam generating unit also includes: Pressure gauge (5), which is installed on the pipe between the steam boiler (7) and the test sample (8), is used to detect the pipe pressure at its location; A check valve (6) is installed on the pipe between the steam boiler (7) and the test sample (8) to prevent high-temperature steam from flowing back into the steam boiler (7).

7. The infrared detection system according to claim 1, characterized in that, Step S7 includes: Determine the temperature difference ΔT r1 If the temperature is greater than 3°C, the area is considered a leak point; otherwise, the area is considered to be free of leaks.

8. The infrared detection system according to claim 7, characterized in that, Step S7 includes: After step S6, steps S2 to S6 are repeated. n different pairs of infrared images are selected to form image pairs, and the temperature difference value of each region in each image pair is calculated. Then, the average of the n temperature differences of each region is taken as the final temperature difference value ΔT of that region. r2 And based on the final temperature difference ΔT r2 The magnitude of the value determines the heat leakage point on the complex metal surface, where n≥2.

9. The infrared detection system according to claim 7, characterized in that, Step S7 includes: After step S6, repeat steps S2 to S6, selecting n different pairs of infrared images to form image pairs, and calculating the temperature difference ΔT in each region of each image pair. r3 Then, according to the temperature difference ΔT r3 The size of the leak point is used to make a preliminary determination. The preliminary judgment results were then investigated, and only when all temperature differences ΔT in a certain area were considered... r3 Only when all indications point to the area as a heat leak point is the area considered the final heat leak point.

10. The infrared detection system according to claim 1, characterized in that, Step S1 includes: S11, First inflation and heating: Adjust the position of the infrared camera so that it faces the test area in the test sample. Then, water from the water tank is pumped to the steam boiler. Set the temperature and flow rate of the high-temperature steam output from the steam boiler. Inject high-temperature steam into the test sample through the steam boiler to heat the test sample. At the same time, measure the pressure P1 in the test sample and capture the infrared image sequence of the test sample using the infrared camera to obtain the first infrared image sequence. At this time, the shut-off valve is open, and the high-temperature steam generated by the steam boiler can be discharged through the shut-off valve after flowing through the test sample. S12, Initial cooling: Water in the water storage tank is used as cooling water and introduced into the test sample through the cooling water delivery pipe to perform initial cooling on the test sample; S13, Re-cooling: External air is introduced into the test sample through a cooling air delivery pipe by a fan to re-cool the test sample and remove the cooling water remaining in the infrared detection system at the same time. S14, Second inflation heating: Adjust the infrared detection system to the state of the first inflation heating, but close the cut-off valve, capture the second infrared image sequence, and record the pressure in the test sample during the second inflation heating as P2, then P2 > P1.

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