Hot-state filter pore size distribution testing device and testing method thereof

Abstract

A device and method for testing the pore size distribution of filter media under hot conditions are disclosed. The testing device includes a heating unit, a sample container, a liquid injection unit, a wetting unit, a gas inlet unit, and a detection unit. The heating unit includes a heating oven. The sample container is centrally located within the detection chamber, with a platform at the bottom of the container for placing the filter media sample. A vent hole is located at the center of this platform. The liquid injection unit injects the wetting liquid into the chamber. The wetting unit evacuates the chamber. The gas inlet unit introduces gas towards the vent. The detection unit includes a pressure detection mechanism, a measuring mechanism, and a circular track. The pressure detection mechanism detects the pressure on the upper and lower sides of the filter media sample. The measuring mechanism is movably mounted on the inner ring of the circular track. An illumination module, a microscope lens, and a CT scanning module are located on the side of the measuring mechanism away from the circular track. Using this device, pore size photographs and pore size distribution data of the filter media sample under simulated high-temperature conditions can be obtained.

Description

Technical Field

[0001] This invention relates to the technical field of filter media, and in particular to a device and method for testing the pore size distribution of filter media under hot conditions. Background Technology

[0002] While industrial production drives economic development, it also brings environmental problems. Baghouse dust collectors are the mainstay of industrial dust removal, and the filter bag, as the core component of a baghouse dust collector, directly affects the dust removal efficiency. The pore size distribution of the filter media used to manufacture the filter bag directly affects its filtration efficiency and service life. Especially under high-temperature conditions, thermal deformation of the material may lead to changes in the pore structure, thereby affecting dust removal performance.

[0003] Existing testing technologies are mostly based on ambient temperature environments, which makes it difficult to accurately reflect the microscopic characteristics of filter media under actual operating conditions. Summary of the Invention

[0004] The purpose of this invention is to provide a device and method for testing the pore size distribution of filter media under hot conditions. This device integrates heating, wetting and imaging systems to achieve accurate measurement of the pore size distribution of filter media under hot conditions, making up for the shortcomings of traditional methods and providing reliable technical support for the performance evaluation of filter media.

[0005] To achieve the above objectives, the solution of the present invention is: A hot filter media pore size distribution testing device includes a heating unit, a sample container, a liquid injection unit, an immersion unit, an air inlet unit, and a detection unit; The heating unit includes a heating oven, which has a spherical detection chamber, and the sample container and the detection unit are disposed inside the detection chamber; The sample container is a high-temperature resistant and transparent cylindrical open container, and is centrally located in the detection chamber. The bottom of the sample container is a platform for placing filter material samples, and the center of the platform has a vent hole that connects to the bottom of the sample container. The liquid injection unit is used to inject the wetting liquid into the cavity; the wetting unit is used to evacuate the cavity so that the filter material sample is fully immersed in the wetting liquid; the air inlet unit is used to input gas toward the air vent. The detection unit includes a pressure detection mechanism, a measuring mechanism, and two circular tracks. The pressure detection mechanism is used to detect the pressure on the upper and lower sides of the filter sample. The two circular tracks are concentrically arranged with the detection chamber and surround the sample container at a certain angle. At least one measuring mechanism is movably installed on the inner ring surface of the circular tracks. The measuring mechanism is provided with an illumination module, a microscope head, and a CT scanning module on the side away from the circular tracks.

[0006] Furthermore, a hollow support rod is connected to the bottom of the sample container. The lower end of the support rod is connected to the bottom of the detection chamber. The inner cavity of the support rod is connected upward to the vent. The lower end of the inner cavity of the support rod is connected to the air intake pipe of the air intake unit.

[0007] Furthermore, the air intake unit includes the air intake pipe, a gas pressure sensor, and a gas cylinder; one end of the air intake pipe is provided with a switch valve to connect to the lower end of the inner cavity of the support rod, and the other end of the air intake pipe is connected to the gas cylinder; the gas pressure sensor is located in the middle of the air intake pipe.

[0008] Furthermore, the pressure detection mechanism includes at least two pressure sensors, which are located above and below the filter sample in the placement platform, respectively. The lower pressure sensor is located at the upper end of the inner cavity of the support rod below the air vent, and the upper pressure sensor is located on the inner wall of the sample container cavity.

[0009] Furthermore, the heating oven is composed of two hemispheres that are interlocked and sealed, with several snap fasteners spaced circumferentially at the joint between the two hemispheres; the heating unit also includes a heating mechanism, a heat preservation mechanism, a temperature sensor, and a PID temperature control module for heating and maintaining the temperature of the detection chamber; the heat preservation mechanism includes two hemispherical heat preservation layers respectively disposed on the inner walls of the two hemispheres, the heating mechanism includes two heating tubes respectively disposed inside the heat preservation mechanism in the two hemispheres, the temperature sensor is multiple and evenly distributed between the heating tubes, and the PID temperature control module is disposed outside the detection chamber and electrically connected to the heating mechanism and the temperature sensor.

[0010] Furthermore, the injection unit includes an injection pipe, a pump, and a storage container. One end of the injection pipe extends into the detection chamber of the heating oven and is connected to the cavity of the sample container. The other end of the injection pipe is connected to the pump, which is installed on the storage container and is used to draw the wetting liquid in the storage container.

[0011] Furthermore, the immersion unit includes a conduit and a vacuum pump. One end of the conduit extends from the outside into the cavity inside the heating oven, and the other end of the conduit is connected to the vacuum pump, which is used to create a vacuum.

[0012] Furthermore, the measuring mechanism includes a walking mechanism that allows the sample container to rotate along a circular track; the microscope head and CT scanning module are arranged side by side, and the illumination module includes several illumination lamps disposed around the periphery of the microscope head and CT scanning module.

[0013] Furthermore, one of the two circular tracks is horizontally positioned, while the other circular track is inclined at a 45-degree angle to the horizontally positioned circular track. The inclined circular track is located outside the horizontally positioned circular track, and there is a gap between them for the measuring mechanism to pass through. The outer ring surfaces of the two circular tracks are respectively connected and fixed to the inner wall of the detection chamber by several connecting rods.

[0014] The present invention also provides a method for testing the pore size distribution of filter media under hot conditions, using the aforementioned testing device, and comprising the following steps: S1. Turn on the heating oven, place the selected filter material sample to be tested on the platform, and ensure that it is flat and wrinkle-free, then turn off the heating oven. S2. Start the liquid injection unit to inject the wetting liquid into the sample container. At the same time, the wetting unit works in concert to make the wetting liquid evenly penetrate into the micropores of the filter material sample. S3. Start the heating mechanism and control the temperature field inside the heating oven to maintain a constant high temperature between 200 and 300 degrees Celsius so that the filter material sample can reach the preset working conditions in a stable thermal field. S4. Adjust the air pressure of the intake unit to 0.5~0.6 MPa, and input nitric oxide gas into the vent. S5. Start the measurement unit. The measurement mechanism in the measurement unit moves along the circular track and repeatedly scans the surface of the filter material sample. With the cooperation of the illumination module and the microscope, the pore size of the filter material sample under the simulated actual working conditions at high temperature is obtained. The pore size distribution data of the filter material sample under the simulated actual working conditions at high temperature is obtained by CT scanning. The capillary pressure change of the filter material sample is recorded by the pressure sensor.

[0015] By adopting the above technical solution, this invention tests the performance of filter media. A heating oven is used for heating, and a liquid injection unit and a wetting unit are employed to fully wet the filter media. Then, an air inlet unit is used to input gas towards the filter media, facilitating testing using the immersion pressure method. Simultaneously, a measuring unit on a circular track, along with an illumination module and a microscope, allows for the acquisition of pore size images of the filter media sample under simulated high-temperature conditions. CT scanning provides pore size distribution data of the filter media sample under simulated high-temperature conditions, facilitating subsequent modeling. A pressure detection mechanism records changes in capillary pressure within the filter media. Subsequently, with the corresponding algorithm model, a three-dimensional pore size distribution map can be generated through fusion analysis, achieving dynamic reconstruction of the filter media's microstructure under high-temperature conditions. The entire testing process is conducted in the sealed environment of the heating oven, effectively avoiding external temperature and humidity interference and ensuring data authenticity. Attached Figure Description

[0016] Figure 1 This is a perspective view of the testing device according to an embodiment of the present invention; Figure 2for Figure 1 Exploded view; Figure 3 This is a cross-sectional schematic diagram of the heating unit according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the measuring mechanism according to an embodiment of the present invention; Figure 5 This is a partial cross-sectional view of the sample container in an embodiment of the present invention; Labeling explanation: Filter media sample 10; Heating unit 1, heating oven 11, hemisphere 111, buckle 112, pulley base 113, control rod 114, detection chamber 115, heating mechanism 12, heat preservation mechanism 13, temperature sensor 14, PID temperature control module 15; Sample container 2, cavity 21, placement platform 211, vent 212, support rod 22; Injection unit 3, injection pipe 31, liquid pump 32, liquid storage container 33; Immersion unit 4, conduit 41, vacuum pump 42; 5. Intake unit 5, intake pipe 51, gas pressure sensor 52, gas cylinder 53, switch valve 54; The system includes a detection unit 6, a pressure detection mechanism 61, a pressure sensor 611, a measuring mechanism 62, an illumination module 621, a microscope head 622, a CT scanning module 623, a circular track 63, and a connecting rod 64. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0018] like Figure 1 and Figure 2 As shown, the hot filter media pore size distribution testing device of this embodiment includes a heating unit 1, a sample container 2, a liquid injection unit 3, a wetting unit 4, an air inlet unit 5, and a detection unit 6.

[0019] The heating unit 1 includes a spherical heating oven 11, which is composed of two hemispheres 111 that are interlocked and sealed. Several snap fasteners 112 can be circumferentially spaced at the seam between the two hemispheres 111, allowing the two hemispheres 111 to be interlocked or separated. In this embodiment, the two hemispheres 111 can be interlocked left and right, and both can have a wheeled base 113 at their bottom. Control rods 114 can be installed on opposite sides to move the wheels of the hemispheres 111, thus enabling the two hemispheres 111 to open and close.

[0020] After the two hemispheres 111 are fastened together, a spherical detection chamber 115 is formed inside; the detection chamber 115 is used to house the sample container 2 and the detection unit 6.

[0021] The liquid injection unit 3, the wetting unit 4, and the air intake unit 5 can be located on the outside of the heating oven 11.

[0022] The heating unit 1 further includes a heating mechanism 12, a heat preservation mechanism 13, a temperature sensor 14, and a PID temperature control module 15 for heating and maintaining the temperature of the detection chamber 115. The heat preservation mechanism 13 may include two hemispherical heat preservation layers respectively disposed on the inner walls of the two hemispheres 111. The heating mechanism 12 may include two heating tubes respectively disposed on the inner side of the heat preservation mechanism 13 in the two hemispheres 111 for heating the detection chamber 115. There may be multiple temperature sensors 14, which may be evenly distributed between the tubes of the heating tubes for detecting the temperature inside the detection chamber 115. The PID temperature control module 15 may be disposed outside the detection chamber 115 and electrically connected to the heating mechanism 12 and the temperature sensors 14. It can adjust the heating mechanism 12 inside the detection chamber 115 according to the temperature detected by each temperature sensor 14, so that the temperature field inside the detection chamber 115 can be maintained at a predetermined temperature, usually between 200 degrees and 300 degrees.

[0023] The PID temperature control module 15 is illustrated in a schematic diagram. For its specific working principle, please refer to existing technologies.

[0024] The sample container 2 is a high-temperature resistant and transparent cylindrical open container. The bottom of the cavity 21 of the sample container 2 is a placement platform 211, which is used to place the filter material sample 10 to be tested. The center of the placement platform 211 is provided with a vent 212 that connects to the bottom surface of the sample container 2. The sample container 2 can be made of high-temperature resistant transparent glass or transparent ceramic.

[0025] The sample container 2 can be centrally located inside the detection chamber 115 with its opening facing upwards. A support rod 22 can be connected to the bottom of the sample container 22, and the lower end of the support rod 22 is connected to the bottom of the detection chamber 115.

[0026] The liquid injection unit 3 includes an injection pipe 31, a liquid pump 32, and a liquid storage container 33. One end of the injection pipe 31 extends into the detection chamber 115 of the heating oven 11 and is connected to the cavity 21 of the sample container 2. The other end of the injection pipe 31 is connected to the liquid pump 32, which is installed on the liquid storage container 33 and is used to draw the wetting liquid in the liquid storage container 33 and inject the wetting liquid into the cavity 21 through the injection pipe 31. The wetting liquid can be silicone oil.

[0027] The immersion unit 4 includes a conduit 41 and a vacuum pump 42. One end of the conduit 41 extends from the outside into the heating oven 11, specifically into the cavity 21 of the sample container 2. The other end of the conduit 41 is connected to the vacuum pump 42, which is used to evacuate the sample container 2 in the detection chamber 115 so that the filter material sample on the placement platform 211 can be fully immersed in the immersion liquid, allowing the sample to fully absorb the liquid without generating bubbles.

[0028] The air intake unit 5 includes an air intake pipe 51, a gas pressure sensor 52, and a gas cylinder 53. One end of the air intake pipe 51 is connected to the lower end of the heating oven 11 and is connected to the lower end of the inner cavity of the support rod 22 in the detection chamber 115. The upper end of the inner cavity of the support rod 22 is connected upward to the air vent 212 on the bottom platform 211 of the cavity 21. The other end of the air intake pipe 51 is connected to the gas cylinder 53. In this way, the gas cylinder 53 can input gas, such as nitric oxide, into the sample container 2, which is convenient for testing experiments using the bubble pressure method (bubble point method).

[0029] The gas pressure sensor 52 can be installed in the middle of the air inlet pipe 51 to confirm the pressure of the gas output from the gas cylinder and to verify the pressure of the gas cylinder outlet valve, ensuring that the gas pressure in the input sample container 2 meets the requirements.

[0030] Meanwhile, a switching valve 54 may be provided between the lower end of the air inlet pipe 51 and the heating oven 11. When the immersion unit 4 evacuates the detection chamber 115, the switching valve 54 can be closed to block the connection between the air inlet pipe 51 and the detection chamber 115.

[0031] The detection unit 6 includes a pressure detection mechanism 61, a measuring mechanism 62, and two circular tracks 63.

[0032] See Figure 5The pressure detection mechanism 61 includes at least two pressure sensors 611, which are located above and below the filter sample 10 in the placement platform 211, respectively. Specifically, the lower pressure sensor 611 can be set at the upper end of the inner cavity of the support rod 22 below the vent 212, and can detect the gas pressure entering the vent 212, that is, detect the pressure below the filter sample 10. The upper pressure sensor 611 can be set on the inner wall of the cavity 21 of the sample container 2, and can detect the pressure above the filter sample 10. Thus, by detecting the pressure above and below the filter sample 10, the pressure change difference after the gas passes through the filter sample 10 can be obtained.

[0033] Two circular tracks 63 are concentrically arranged with the detection chamber 115 and surround the sample container 2 at a certain angle. Specifically, one circular track 63 can be horizontally arranged, and the other circular track 63 can be arranged at approximately a 45-degree angle with the horizontally arranged circular track 63. The outer ring surface of the circular track 63 can be connected and fixed to the inner wall of one hemisphere 111 of the detection chamber 115. At least one measuring mechanism 62 is movably installed on the inner ring surface of each circular track 63. In this embodiment, multiple measuring mechanisms 62 are evenly spaced circumferentially on each circular track 63. The side of the measuring mechanism 62 away from the circular track 63 is provided with an illumination module 621, a microscope head 622, and a CT scanning module 623. The microscope head 622 and the CT scanning module 623 can be arranged side by side. The illumination module 621 includes several illumination lamps arranged around the microscope head 622 and the CT scanning module 623.

[0034] In this embodiment, each measuring mechanism 62 may be equipped with a walking mechanism (not shown in the figure, but can be referred to in the prior art), and can rotate around the sample container 2 along the circular track 63 by means of the walking mechanism, so as to realize illumination, microscopic imaging and CT scanning of the filter material sample in the sample container 2.

[0035] Both the pressure sensor 611 and the measuring mechanism 62 are high-temperature resistant devices, capable of operating normally within the high-temperature detection chamber 115.

[0036] In this embodiment, one of the two circular tracks 63 is horizontally positioned, while the other is vertically tilted. This avoids interference between the circular track 63 and the support rod 22 and the guide tube 41, and also allows each measuring mechanism 62 to completely capture and scan the entire filter material sample 10.

[0037] In this embodiment, the inclined arc track 63 is located outside the horizontally arranged ring track 63, and there is a gap between them for the measuring mechanism 62 to move through; the outer ring surfaces of the two arc tracks 63 are respectively connected and fixed to the inner wall of the detection chamber 115 through a number of connecting rods 64, and specifically the outer ring surfaces of the two arc tracks 63 are respectively connected to the inner wall of the hemisphere 111 through connecting rods 64.

[0038] Using the aforementioned testing apparatus, this embodiment can employ the following hot-state filter media pore size distribution testing method to test the filter media performance.

[0039] Specifically, this may include the following steps: Select the filter material sample 10 to be tested and cut it to a size suitable for the material platform 211, for example, cut it into a circle with a radius of 5 cm.

[0040] S1. Open the heating oven 11, place the selected filter material sample 10 to be tested on the placement platform 211, and ensure that it is flat and wrinkle-free. Then close the heating oven 11 and ensure that the two hemispheres 111 are locked together and sealed.

[0041] S2. Start the liquid injection unit 3. The liquid pump 32 accurately injects the wetting liquid into the sample container 2 along the liquid injection tube 31. At the same time, the vacuum pump 42 of the wetting unit 4 works in coordination to make the wetting liquid evenly penetrate into the micropores of the filter material sample 10. S3. Start the heating mechanism 12, set the target temperature through the PID temperature control module 15 and adjust it in real time through the temperature sensor 14, and cooperate with the heat preservation mechanism 13 to maintain the temperature field inside the heating oven 11 at a constant high temperature between 200 and 300 degrees, so that the filter material sample 10 can reach the preset working conditions in a stable thermal field. S4. Ensure that the air intake unit 5 has sufficient gas and check that the air pipe is connected correctly. After checking that everything is correct, open the main valve of the gas cylinder and adjust the air pressure to 0.5~0.6 MPa, and open the switch valve 54 under the storage platform 211. S5. Start the measurement unit. Each measurement mechanism 62 in the measurement unit moves along the circular track 63 and repeatedly scans the surface of the filter material sample 10. With the cooperation of the illumination module 621 and the microscope head 622, the pore size photograph of the filter material sample 10 under the simulated actual working conditions at high temperature can be obtained. The pore size distribution data of the filter material sample 10 under the simulated actual working conditions at high temperature can be obtained by CT scanning, which is convenient for subsequent modeling. Combined with the pressure sensor 611, the capillary pressure change of the filter material sample is recorded. When the measuring unit is working, it can take 600 photos per minute and rotate once every 2 minutes. The above describes the testing method of this embodiment. The entire testing process is carried out in a closed environment, which effectively avoids interference from external temperature and humidity and ensures the authenticity of the data. Through multiple sets of repeated experiments, the measurement results of the device have good reproducibility and stability, and can be widely used in the testing and improvement of filter material performance in the fields of high-temperature flue gas treatment such as power and metallurgy.

[0042] The testing device of this invention can obtain pore size photographs and pore size distribution data of filter media under hot conditions, as well as capillary pressure changes. The data obtained by the measurement unit is then transmitted to the data processing unit. With the help of the corresponding algorithm model, a three-dimensional pore size distribution map can be generated through fusion analysis, thereby realizing the dynamic reconstruction of the microstructure of the filter media under high temperature conditions.

[0043] The algorithm model mainly references the following methods: 1. Graphical method: Pore ​​image analysis is a method for digitally and quantitatively analyzing the pores of thin rock sections using backscatter scanning electron microscopy or conventional microscopy. It is used to determine parameters such as pore size and shape. The principle involves setting a grayscale threshold to distinguish pores from minerals, collecting data such as pore area (A), perimeter (P), and diameter, and then calculating three parameters: equivalent circle diameter (ECD = 4πA(1 / 2)), roundness (R = 4πA / P²), and shape factor. During analysis, the microscope magnification needs to be adjusted according to different pore sizes, thousands of pore parameters are processed in batches, and correlations are established with reservoir permeability and water saturation.

[0044] With technological advancements, microscopic equipment combined with artificial intelligence software has enabled multi-scale pore image analysis, encompassing intelligent pore extraction and 3D reconstruction techniques across micrometer- to nanometer-scale CT. Deep learning and image recognition algorithms have been used to construct intelligent pore recognition models, enabling the calculation of pore radius and volume distribution, as well as full-scale characterization, through multi-level, multi-scale image input.

[0045] 2. Soaking and pressing method: The bubble pressure method (bubble point method) works by generating bubbles when gas from one side of the sample passes through the sample and reaches the wetting liquid on the other side. The pore size of the sample is calculated using this method. Its detection principle is based on capillary theory. When gas passes through a liquid-wetted diaphragm, it must overcome the additional pressure (bubble pressure) created by the surface tension of the liquid within the pores of the diaphragm. This pressure is calculated using the formula: d = 4γcosθ / P, where d is the pore diameter, γ is the surface tension of the wetting liquid, θ is the contact angle between the wetting liquid and the diaphragm, and P is the gas pressure. By gradually increasing the gas pressure and recording the gas permeation rate at different pressures, the maximum pore size, average pore size, and pore size distribution can be calculated.

[0046] The above description is merely a preferred embodiment of the present invention, and the scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, equivalent changes and modifications without departing from the principle of the present invention should still fall within the scope of protection of the present invention.

[0047] In the description of the embodiments of this application, it should be understood that the indicated orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings, or the orientations or positional relationships commonly used when the product is in use, or the orientations or positional relationships commonly understood by those skilled in the art. These are only for the convenience of describing this application and simplifying the description, and are not intended to indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. In the description of this application, "a plurality of" and "several" mean two or more, unless otherwise explicitly specified.

Claims

1. A device for testing the pore size distribution of filter media under hot conditions, characterized in that: It includes a heating unit, a sample container, a liquid injection unit, an immersion unit, an air intake unit, and a detection unit; The heating unit includes a heating oven, which has a spherical temperature-controlled detection chamber inside. The sample container and the detection unit are disposed inside the detection chamber. The sample container is a high-temperature resistant and transparent cylindrical open container, and is centrally located in the detection chamber. The bottom of the sample container is a platform for placing filter material samples, and the center of the platform has a vent hole that connects to the bottom of the sample container. The liquid injection unit is used to inject the wetting liquid into the cavity; the wetting unit is used to evacuate the cavity so that the filter material sample is fully immersed in the wetting liquid; the air inlet unit is used to input gas toward the air vent. The detection unit includes a pressure detection mechanism, a measuring mechanism, and two circular tracks. The pressure detection mechanism is used to detect the pressure on the upper and lower sides of the filter sample. The two circular tracks are concentrically arranged with the detection chamber and surround the sample container at a certain angle. At least one measuring mechanism is movably installed on the inner ring surface of the circular tracks. The measuring mechanism is provided with an illumination module, a microscope head, and a CT scanning module on the side away from the circular tracks.

2. The hot-state filter media pore size distribution testing device according to claim 1, characterized in that: The sample container is connected to a hollow support rod at the bottom. The lower end of the support rod is connected to the bottom of the detection chamber. The inner cavity of the support rod is connected to the vent at the top. The lower end of the inner cavity of the support rod is connected to the air inlet pipe of the air inlet unit.

3. The hot-state filter media pore size distribution testing device according to claim 2, characterized in that: The air intake unit includes the air intake pipe, a gas pressure sensor, and a gas cylinder; one end of the air intake pipe is equipped with a switch valve that can be opened and closed to connect to the lower end of the inner cavity of the support rod, and the other end of the air intake pipe is connected to the gas cylinder; the gas pressure sensor is located in the middle of the air intake pipe.

4. The hot-state filter media pore size distribution testing device according to claim 2, characterized in that: The pressure detection mechanism includes at least two pressure sensors, which are located above and below the filter sample in the placement platform. The lower pressure sensor is located at the upper end of the inner cavity of the support rod below the air vent, and the upper pressure sensor is located on the inner wall of the sample container cavity.

5. The hot-state filter media pore size distribution testing device according to claim 1, characterized in that: The heating oven is composed of two hemispheres that are interlocked and sealed together, with several snap fasteners spaced circumferentially at the seam between the two hemispheres. The heating unit also includes a heating mechanism, a heat preservation mechanism, temperature sensors, and a PID temperature control module for heating and maintaining the temperature of the detection chamber. The heat preservation mechanism includes two hemispherical heat preservation layers respectively disposed on the inner walls of the two hemispheres. The heating mechanism includes two heating tubes respectively disposed inside the heat preservation mechanism in the two hemispheres. There are multiple temperature sensors, which are evenly distributed between the heating tubes. The PID temperature control module is located outside the detection chamber and is electrically connected to the heating mechanism and the temperature sensors.

6. The hot-state filter media pore size distribution testing device according to claim 1, characterized in that: The liquid injection unit includes an injection pipe, a liquid pump, and a liquid storage container. One end of the injection pipe extends into the detection chamber of the heating oven and is connected to the cavity of the sample container. The other end of the injection pipe is connected to the liquid pump, which is installed on the liquid storage container and is used to draw the wetting liquid in the liquid storage container.

7. The hot-state filter media pore size distribution testing device according to claim 1, characterized in that: The immersion unit includes a conduit and a vacuum pump. One end of the conduit extends from the outside into the cavity inside the heating oven, and the other end of the conduit is connected to the vacuum pump, which is used to create a vacuum.

8. The hot filter media pore size distribution testing device according to claim 1, characterized in that: The measuring mechanism includes a walking mechanism, which allows the sample container to rotate along a circular track. The microscope head and CT scanning module are arranged side by side, and the illumination module includes several illumination lamps located around the microscope head and CT scanning module.

9. The hot-state filter media pore size distribution testing device according to claim 1, characterized in that: One of the two circular tracks is horizontally positioned, while the other circular track is inclined at a 45-degree angle to the horizontal circular track. The inclined circular track is located outside the horizontal circular track, and there is a gap between them for the measuring mechanism to pass through. The outer ring surfaces of the two circular tracks are respectively connected and fixed to the inner wall of the detection chamber by several connecting rods.

10. A method for testing the pore size distribution of filter media under hot conditions, characterized in that, The testing apparatus described in any one of claims 1-9 comprises the following steps: S1. Turn on the heating oven, place the selected filter material sample to be tested on the platform, and ensure that it is flat and wrinkle-free, then turn off the heating oven. S2. Start the liquid injection unit to inject the wetting liquid into the sample container. At the same time, the wetting unit works together to make the wetting liquid evenly penetrate into the micropores of the filter material sample. S3. Start the heating mechanism and control the temperature field inside the heating oven to maintain a constant high temperature between 200 and 300 degrees Celsius so that the filter material sample can reach the preset working conditions in a stable thermal field. S4. Adjust the air pressure of the intake unit to 0.5~0.6 MPa, and input nitric oxide gas into the vent. S5. Start the measurement unit. The measurement mechanism in the measurement unit moves along the circular track and repeatedly scans the surface of the filter material sample. With the cooperation of the illumination module and the microscope, the pore size of the filter material sample under the simulated actual working conditions at high temperature is obtained. The pore size distribution data of the filter material sample under the simulated actual working conditions at high temperature is obtained by CT scanning. The capillary pressure change of the filter material sample is recorded by the pressure sensor.

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