Local filtering efficiency detection device

Abstract

The utility model discloses a local filtering efficiency detection device, which belongs to the technical field of biological safety protection, and comprises a scanning dust generating device, a filtering device and a sampling device, the scanning dust generating device and the sampling device are respectively arranged at the upstream and the downstream of a filter, the filter is arranged at the air inlet of the filtering device, and the sampling device is arranged at the air outlet of the filtering device. The sampling device is located in an inner cavity of the filtering device, the scanning and dust generating device is used for scanning and moving within the breadth range of the filter, the sampling device is used for sampling airflow passing through the filter in real time, and a leakage point is positioned through abnormal rising of a sampling value. According to the utility model, the scanning dust generation device is used for scanning dust generation at the upstream of the filter, the local upstream concentration of the filter is improved, the local leakage defect position is accurately identified by recording the sampling concentration change of the sampling device at the downstream fixed point, and ideal test precision can be obtained on the basis of lower cost, safety and reliability.

Description

Technical Field

[0001] The utility model relates to the technical field of biosafety protection, in particular to a local filtration efficiency detection device. Background Technique

[0002] With the large-scale construction of high-level biosafety protection facilities, the selection and evaluation of relevant protection equipment in corresponding high-level laboratories have received more and more attention. The exhaust air of air-conditioning systems in high-level biosafety laboratories, biosafety protection workshops, etc. must be filtered by exhaust high-efficiency filters before being discharged, and the exhaust high-efficiency filters must be able to perform in-situ leak detection tests.

[0003] At present, there are two in-situ leak detection methods used in engineering: a) maintaining a uniform and stable particle concentration upstream of the filter, and using a movable small-area sampling port near the downstream of the filter to perform point-by-point scanning tests on the filter element and the frame to detect local leakage defects, the scanning leak detection method; b) maintaining a uniform and stable particle concentration upstream of the filter, setting sampling points at a uniform concentration downstream of the filter, and calculating the overall transmittance of the filter by comparing the upstream and downstream concentrations, the efficiency leak detection method.

[0004] In engineering applications, the above two methods have the following problems:

[0005] (1) The leak detection exhaust device by the full efficiency method has great advantages in equipment cost. However, existing data shows that the accuracy gap between the overall transmittance and the local transmittance is significant, and the overall transmittance of the same leak hole is only 2.4% - 6.1% of the local transmittance. At the same time, the full efficiency method leak detection can only judge the overall efficiency of the filter and cannot effectively identify the types and positions of local leakage defects of the filter.

[0006] (2) The scanning leak detection method can effectively judge the types of local leakage defects of the filter and identify the defect positions through point-by-point scanning. The mainstream products in the market application in the past 10 years are all scanning exhaust high-efficiency filter devices. To realize the scanning drive action downstream of the filter, the shaft body needs to pass through an opening in the box body, and only grease sealing can be used at the place where the shaft body passes through, and there is a possibility of leakage after using for a period of time. In addition, during the scanning process, there are a large number of transmission components inside the downstream cavity of the filter, which will increase the possibility of problems such as shaft detachment, damage, and trachea blockage after long-term use. At the same time, the price of the leak detection exhaust high-efficiency filter device is much higher than that of the efficiency method exhaust high-efficiency filter device.

[0007] It can be seen that the above-mentioned existing exhaust high-efficiency filter devices still have inconveniences and defects in structure and application and urgently need to be further improved. How to create a device that can effectively identify the types and positions of local leakage defects of the filter, has a low cost and is safe and reliable has become the goal that the current industry urgently needs to improve. Summary of the Utility Model

[0008] The purpose of the present utility model is to provide a local filtration efficiency detection device to solve the problems existing in the above-mentioned prior art. By using a scanning dust generation device to scan and generate dust upstream of the filter, the local upstream concentration of the filter is increased. By recording the change in the sampling concentration of the sampling device at a fixed point downstream, the position of local leakage defects can be accurately identified, and ideal test accuracy can be obtained on the basis of low cost, safety and reliability.

[0009] To achieve the above purpose, the present utility model provides the following solutions:

[0010] The present utility model provides a local filtration efficiency detection device, including a scanning dust generation device and a sampling device. The scanning dust generation device and the sampling device are respectively arranged upstream and downstream of the filter. The filter is installed at the air inlet of the filtering device. The sampling device is located inside the filtering device. The scanning dust generation device is used to scan and move within the width range of the filter, and the sampling device is used to perform real-time sampling on the airflow passing through the filter, and locate the leakage point through the abnormal increase of the sampling value.

[0011] Preferably, the scanning dust generation device includes a scanning dust generation head and a scanning enclosure that penetrates from front to back. The scanning enclosure is installed at the air inlet. The scanning dust generation head is located inside the scanning enclosure and faces the filter. The scanning dust generation head is connected with a hollow scanning connecting rod, and the end of the scanning connecting rod far from the scanning dust generation head is an injection port.

[0012] Preferably, rake-shaped grooves are arranged on the side of the scanning enclosure. The scanning connecting rod penetrates through the rake-shaped grooves and can move within the rake-shaped grooves. The rake-shaped grooves include a main groove for changing the scanning position longitudinally and rake tooth grooves for lateral scanning movement. The rake tooth grooves are uniformly distributed on the main groove, and the main groove is communicated with the rake tooth grooves.

[0013] Preferably, the scanning dust generation head adopts a scanning funnel. The inlet end of the scanning funnel is a small-diameter end, and the outlet end of the scanning funnel is a large-diameter end. The small-diameter end is connected with the scanning connecting rod, and the large-diameter end faces the filter.

[0014] Preferably, the sampling device includes a sampling head, a conduit and a sampling instrument. The sampling head is located inside the filtering device, and the conduit connects the sampling head and the sampling instrument.

[0015] Preferably, the filtering device includes a first ventilation section and a second ventilation section. One end of the first ventilation section is provided with the air inlet, the other end of the first ventilation section is connected with the second ventilation section, the inner diameter of the first ventilation section is larger than the inner diameter of the second ventilation section, and the sampling head is arranged inside the second ventilation section.

[0016] Preferably, the sampling head includes a sampling tube, and a sampling port is provided on the windward surface of the sampling tube.

[0017] Preferably, the sampling tube includes an I-shaped main sampling tube and a sampling branch tube vertically connected to the transverse arm of the I-shaped main sampling tube. The I-shaped main sampling tube and the sampling branch tube are in the same plane, and this plane is perpendicular to the air flow direction.

[0018] The present utility model also provides a method for detecting local filtration efficiency, which uses the local filtration efficiency detection device described above, and includes the following steps:

[0019] S1. Turn on the scanning dust generation device;

[0020] S2. Move the scanning dust generation head close to the filter;

[0021] S3. Move the scanning dust generation head at a uniform speed, and the moving path covers the entire width of the filter;

[0022] S4. Monitor the downstream sampling data in real time. When the scanning dust generation head is located at the leakage point, the downstream sampling value will increase abnormally, and the leakage point can be located.

[0023] Preferably, the outlet diameter of the scanning dust generation head is greater than or equal to the moving distance per second, and the abnormal data appears at a specific leakage point for more than one second.

[0024] The present utility model has achieved the following technical effects compared with the prior art:

[0025] The present utility model uses a scanning dust generation device to generate dust upstream of the filter, increasing the local upstream concentration of the filter. By recording the change in the sampling concentration of the sampling device at a fixed downstream point, the local leakage defect position can be accurately identified. Compared with the full-efficiency leak detection method, the test accuracy is improved. Compared with the scanning leak detection method, the cost is reduced and the safety and reliability are improved. It can obtain ideal test accuracy on the basis of low cost, safety and reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0027] Figure 1 It is a schematic diagram of the overall structure of the present utility model;

[0028] Figure 2Schematic diagram of the dust emission device for scanning

[0029] Figure 3 Schematic diagram of the sampling device

[0030] Figure 4 Front view of the sampling head

[0031] Figure 5 Experimental device for verifying the feasibility of the scanning method

[0032] Figure 6 Experimental device for the upstream uniform condition

[0033] Figure 7 Experimental device for the upstream non-uniform condition

[0034] Figure 8 Verification of the identifiability of local defects during the dynamic process of upstream dust emission scanning

[0035] Among them, 1. Dust emission device for scanning; 11. Scanning enclosure; 12. Connector; 13. Scanning dust emission head; 14. Scanning connecting rod; 15. Injection port; 16. Rake-shaped groove; 2. Filter device; 21. First ventilation section; 22. Second ventilation section; 23. Filter; 3. Sampling device; 31. Sampling head; 311. Sampling main pipe; 312. Sampling branch pipe; 32. Conduit

[0036] 10. Prefilter; 20. First dust emission port; 30. Aerosol flow equalizing orifice plate; 40. First sampling point; 50. Aerosol injection port; 60. Second dust emission port; 70. Test high-efficiency filter; 80. Second sampling point; 90. Flexible connection; 100. Exhaust fan Detailed implementation manners

[0037] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention

[0038] The purpose of the present invention is to provide a local filtration efficiency detection device to solve the problems existing in the prior art. By using a dust emission device for scanning to emit dust upstream of the filter, the local upstream concentration of the filter is increased. By recording the change in the sampling concentration of the sampling device at a fixed point downstream, the position of local leakage defects can be accurately identified, and ideal test accuracy can be obtained on the basis of low cost, safety and reliability

[0039] To make the above objects, features, and advantages of the present utility model more obvious and understandable, the present utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0040] As Figures 1 to 4 shown, the present utility model provides a local filtration efficiency detection device, including a scanning dust generating device 1 and a sampling device 3. The scanning dust generating device 1 is used to generate an aerosol airflow, and the sampling device 3 is used to detect the aerosol concentration after being filtered by the filter 23. The scanning dust generating device 1 and the sampling device 3 are respectively arranged upstream and downstream of the filter 23, that is, the aerosol airflow emitted by the scanning dust generating device 1 reaches the sampling device 3 after being filtered by the filter 23. The filtering device 2 can be made of stainless steel in the shape of a square or a circle, etc. The filter 23 is installed at the air inlet of the filtering device 2 in the form of being pressed by a rubber strip or sealed by a liquid tank. The sampling device 3 is located inside the filtering device 2. When the scanning dust generating device 1 works, it scans and moves within the area of the filter 23, so that the aerosol airflow gradually passes through different areas of the filter 23. The sampling device 3 samples the airflow passing through the filter 23 in real time. If there is a local leakage point in the filter 23, when the scanning dust generating device 1 passes through this leakage point, it will cause the sampling value of the sampling device 3 to increase abnormally. Thus, the leakage point can be located by the abnormal increase of the sampling value.

[0041] The present utility model uses the scanning dust generating device 1 to generate dust upstream of the filter 23, improves the local upstream concentration of the filter 23, and accurately identifies the position of local leakage defects by recording the change of the sampling concentration of the sampling device 3 at a fixed point downstream. Compared with the full-efficiency leak detection method, the test accuracy is improved. Compared with the scanning leak detection method, the cost is reduced and the safety and reliability are improved. It can obtain ideal test accuracy on the basis of low cost, safety and reliability.

[0042] As Figure 2 shown, the scanning dust generating device 1 includes a scanning dust generating head 13 and a scanning enclosure 11 that penetrates through from front to back. The scanning enclosure 11 is installed at the air inlet of the filtering device 2 through a connecting member 12 (structures such as screws and flanges) to form a channel for aerosol generation. At the same time, the air passing area of the scanning enclosure 11 is larger than the area of the filter 23 so as not to affect the air intake volume of the filter 23. The scanning dust generating head 13 is located inside the scanning enclosure 11 and its outlet faces the filter 23. The scanning dust generating head 13 is connected with a hollow scanning connecting rod 14. One end of the scanning connecting rod 14 far from the scanning dust generating head 13 is an injection port 15, and the injection port 15 is used to connect the dust generating device. The scanning connecting rod 14 is both equivalent to the conveying pipeline of the aerosol and can be used as the moving support of the scanning dust generating head 13, that is, by moving the scanning connecting rod 14, the scanning dust generating head 13 can be driven to scan and move within the area of the filter 23.

[0043] Furthermore, the cross-sectional shape of the scanning enclosure 11 is consistent with the format shape of the filter 23, for example, both are rectangular or circular. Rake-shaped grooves 16 can be provided on the side of the scanning enclosure 11. The rake-shaped grooves 16 are used to restrict and define the movement of the scanning link 14, so that the scanning link 14 completes the scanning action along a certain path. The scanning enclosure 11 can be used as a scanning fixed bracket, and the scanning link 14 can be used as a sliding rod. Specifically, the length direction of the scanning link 14 is perpendicular to the plane where the rake-shaped grooves 16 are located. The scanning link 14 passes through the rake-shaped grooves 16 and can move within the rake-shaped grooves 16. The movement mentioned here includes the movement perpendicular to the plane where the rake-shaped grooves 16 are located and the movement parallel to the plane. The rake-shaped grooves 16 include a main groove and rake teeth grooves that communicate with each other. The rake teeth grooves are evenly distributed, different rake teeth grooves are parallel to each other, the rake teeth grooves are perpendicular to the main groove, the main groove is used to change the scanning position longitudinally, and the rake teeth grooves are used to move the scan laterally. It should be noted that to ensure that every part of the filter 23 can be covered and scanned by the scanning dust generating head 13, the outlet width of the scanning dust generating head 13 should be greater than or equal to the spacing between the rake teeth grooves.

[0044] In a further solution, the scanning dust generating head 13 can adopt a scanning funnel. For example, a scanning funnel with a specification of 1.5 cm × 8 cm (diameter × length) can be used. The inlet end of the scanning funnel is the small-diameter end, and the outlet end of the scanning funnel is the large-diameter end. During application, the small-diameter end is connected to the scanning link 14, the large-diameter end faces the filter 23, and is at a relatively short distance (2 cm to 3 cm) from the windward surface of the filter 23, and scans the entire filter 23 and its frame at a constant speed (1.5 cm / s). The setting of the scanning funnel can increase the coverage area of the scanning dust generating head 13 and ensure the scanning efficiency.

[0045] As Figure 3 and Figure 4 As shown, the sampling device 3 includes a sampling head 31, a conduit 32, and a sampling instrument. Among them, the sampling head 31 is located inside the filtering device 2, and the conduit 32 connects the sampling head 31 and the sampling instrument. The sampling instrument is arranged outside the filtering device 2. The conduit 32 enters the inside of the filtering device 2 through a hole opened on the filtering device 2 and is connected to the sampling head 31. The hole on the filtering device 2 should be sealed. The best placement position of the sampling head 31 is the position where the airflow after passing through the filter 23 has been fully mixed. In this way, the sampling accuracy can be guaranteed, and numerical fluctuations and inaccuracies can be avoided.

[0046] Combined with Figure 1As shown, the filtering device 2 may include a first ventilation section 21 and a second ventilation section 22. One end of the first ventilation section 21 is provided with an air inlet, and the other end of the first ventilation section 21 is connected to the second ventilation section 22. Since the filter 23 is installed at the air inlet, the air flow filtered by the filter 23 will first enter the first ventilation section 21 and then flow into the second ventilation section 22. The inner diameter of the first ventilation section 21 is larger than that of the second ventilation section 22. The first ventilation section 21 itself has a certain length, and the filtered air flow can basically reach a fully mixed state within the first ventilation section 21 or after the first ventilation section 21 ends. Therefore, the sampling head 31 can be arranged in the second ventilation section 22 to sample the fully mixed air flow by using the sampling head 31. In addition, since the inner diameter of the second ventilation section 22 is smaller, the concentration of the filtered air flow can be increased, thereby further improving the sampling accuracy.

[0047] As Figure 3 and Figure 4 shown, the sampling head 31 includes a sampling tube, and the sampling tube can be made of a stainless steel pipe with an inner diameter of 5 mm. A 2-mm hole slot is opened along the pipe on the windward surface of the sampling tube as the sampling port. By setting the sampling tube, the sampling area of the sampling head 31 can be increased, and the air flow can be sampled better by using the sampling port.

[0048] Furthermore, the sampling tube may include an I-shaped sampling main pipe 311 and sampling branch pipes 312 vertically connected to the transverse arms of the I-shaped sampling main pipe 311. The middle of the I-shaped sampling main pipe 311 is communicated with a conduit 32. The I-shaped sampling main pipe 311 and the sampling branch pipes 312 are in the same plane, and the plane is perpendicular to the air flow direction. When the air flow passes through the plane where the sampling tube is located, it can enter the inside of the sampling tube through the sampling port on the sampling tube and then enter the sampling instrument through the conduit 32.

[0049] Combining again with Figures 1 to 4 shown, the present utility model also provides a method for detecting the local filtration efficiency, which can be applied to the local filtration efficiency detection device described above, including the following steps:

[0050] S1. Turn on the scanning dust generating device 1;

[0051] S2. Move the scanning dust generating head 13 of the scanning dust generating device 1 close to the filter 23;

[0052] S3. Move the scanning dust generating head 13 at a constant speed, and the moving path covers the entire area of the filter 23;

[0053] S4. Monitor the sampling data of the downstream sampling device 3 in real time. When the scanning dust generating head 13 is at the leakage point, the downstream sampling value will increase abnormally, and the leakage point can be located.

[0054] Furthermore, the outlet diameter of the dust emission scanning head 13 is greater than or equal to its moving distance per second, so as to ensure that the abnormal data appearance time at a specific leakage point exceeds one second, which can ensure that the aerosol can pass through the leakage point and improve the success rate of leakage point detection.

[0055] The specific embodiments of the local filtration efficiency detection provided by the present utility model are as follows:

[0056] 1) Turn on the dust emission scanning device 1, adjust the compressed air volume and pressure to ensure that the generated aerosol is uniform and stable, and the local upstream concentration at the position where the filter 23 faces the dust emission scanning head 13 is not less than 200,000 particles / 2.83 liters (counter method) or 10 mg / m 3 (photometer method).

[0057] 2) Use a scanning dust emission head 13 with a fixed size (a 1.5 cm × 8 cm scanning funnel). The scanning dust emission head 13 is at a relatively short distance (2 cm - 3 cm) from the windward surface of the filter 23 installed in place. A scanning enclosure 11 is fixedly installed at the air inlet of the filter 23 as a scanning fixed bracket. A graduated scanning connecting rod 14 is used as a sliding rod to connect with the scanning dust emission head 13. When moving the scanning connecting rod 14 on the side of the air outlet, the scanning dust emission head 13 can be linked to move horizontally parallel to the windward surface of the filter 23. By adjusting different positions, the entire surface of the filter 23 can be scanned.

[0058] 3) For holes of the same size, the leakage amount is proportional to the local concentration. By increasing the dust content at the local position upstream of the filter 23, increasing the dust passing amount at the local defect point, and improving the accuracy of downstream sampling to identify defects. At the same time, maintain a reasonable scanning speed (1.5 cm / s) to ensure that the abnormal data appearance time at a specific leakage point exceeds one second. According to relevant experimental data, the downstream concentration value scanned to the defect point can be 10 times higher than that at the defect-free place 4 or more, which can effectively help identify the number and location of local defects of the filter 23 on site.

[0059] 4) Set a sampling device 3 downstream to ensure that the downstream gas sampling value can fully represent the downstream aerosol concentration.

[0060] 5) Monitor the downstream sampling data in real time. When the scanning dust emission head 13 is located at the leakage point, the downstream sampling value will show an abnormal increase, and the leakage point can be located. Select aerosols with an aerodynamic particle size less than 0.5 or 5.0 microns. The test means that can be used include but are not limited to: photometers, laser particle counters, etc.

[0061] Combined Figures 5 to 8 As shown in

[0062] I. Scheme description

[0063] As Figure 5 shown, an experimental device was established to verify the feasibility of the testing method proposed by the present utility model.

[0064] The functions of each part of the experimental device are described as follows:

[0065] The pre-filter 10 is used to pre-filter the test high-efficiency filter 70 to eliminate the influence of environmental atmospheric dust on the experimental results.

[0066] The first dust injection port 20 is used to introduce artificial dust under the upstream uniform working condition.

[0067] The aerosol flow equalizing orifice plate 30 is used to mix the artificial dust emitted from the first dust injection port 20 under the upstream uniform working condition.

[0068] The first sampling point 40 is used to connect the particle sampling instrument to detect the upstream concentration of the test high-efficiency filter 70 under the upstream uniform working condition.

[0069] The aerosol injection port 50 is used to introduce artificial dust through a pipeline under the upstream non-uniform working condition.

[0070] The second dust injection port 60 is used to introduce artificial dust upstream of the test high-efficiency filter 70 under the upstream non-uniform working condition to achieve a local high concentration upstream of the test high-efficiency filter 70.

[0071] For the test high-efficiency filter 70, the filter element and the frame are installed intact, and a leakage point is artificially created to form a local defect.

[0072] The second sampling point 80 is more than ten pipe diameters downstream of the test high-efficiency filter 70. After ensuring the downstream concentration is uniform, the downstream concentration is sampled in the pipeline.

[0073] The flexible connection 90 is used as a shock absorption measure between the pipeline and the exhaust fan 100.

[0074] The exhaust fan 100 is variable-frequency, and the air volume can be adjusted.

[0075] The standard air volume of this experimental device is 1000 m 3 / h. The size of the test high-efficiency filter 70 is 610×610×120. A 0.7-mm standard injection needle is used to artificially create a leakage point; the distance of the downstream test point from the downstream of the test high-efficiency filter 70 is ensured to be not less than ten pipe diameters, and a 2.83 L / min dust particle counter is used for sampling.

[0076] The experimental device can achieve two working conditions for comparison: the upstream uniform condition and the upstream non-uniform condition. Keeping the artificial dust generation amount constant, the artificial dust is respectively introduced into the first dust generation port 20 and the second dust generation port 60. Under the upstream uniform condition, all the artificial dust is evenly dispersed at various positions upstream of the test high-efficiency filter 70; under the upstream non-uniform condition, the artificial dust is introduced near the upstream of the test high-efficiency filter 70 to simulate the actual improved test accuracy in the state where the scanning dust generation head 13 covers local defect points.

[0077] II. Experimental Scheme

[0078] 1. Upstream Uniform Condition

[0079] As Figure 6 shown, the experimental device is used to achieve a uniform dust generation state upstream of the test high-efficiency filter 70. This condition simulates the local defect detection of the test high-efficiency filter 70 by the conventional efficiency method. First, after the pre-filter 10 eliminates the environmental influence, artificial dust is sent into the pipeline from the first dust generation port 20. After being evenly distributed by the aerosol flow equalizing orifice plate 30, a uniform state is achieved, and the artificial dust concentration upstream of the test high-efficiency filter 70 is made uniform. Ensure that the upstream aerosol concentration in the pipeline at the first sampling point 40 is uniform. Under the upstream uniform condition, the upstream concentration value is obtained at the first sampling point 40 through the particle sampling instrument. After the system is stable, when verifying the local defect of the test high-efficiency filter 70, the second sampling point 80 is connected to the particle sampling instrument to obtain the downstream concentration value. The data measured under the upstream uniform condition is used as the system control group.

[0080] 2. Upstream Non-uniform Condition

[0081] As Figure 7 shown, the experimental device is used to achieve a non-uniform dust generation condition upstream of the test high-efficiency filter 70. This condition simulates the difference in downstream testing when the scanning dust generation head 13 covers local defect points. First, after the pre-filter 10 eliminates the environmental influence, artificial dust is sent into the pipeline from the aerosol injection port 50 and ejected through the second sampling point 80, so that the local concentration at the local defect is much greater than other positions. After the system is stable, when verifying the local defect of the test high-efficiency filter 70, the second sampling point 80 is connected to the particle sampling instrument to obtain the downstream concentration value.

[0082] III. Precision Verification of Static Upstream Non-uniform Condition

[0083] The upstream uniform condition and the upstream non-uniform condition are respectively compared. Keeping the dust generation amount of the aerosol dust generation device stable, the aerosol generation device is respectively connected to the first dust generation port 20 and the aerosol injection port 50 of the experimental device, and the second dust generation port 60 is placed at the artificially created leakage point. The following table shows the comparative experimental data.

[0084] Appendix 1 Precision Verification of Static Upstream Non-uniform Condition

[0085]

[0086] IV. Verification of the Identifiability of Local Defects in the Dynamic Process of Upstream Dust Generation Scanning

[0087] Using a scanning funnel with a size of 1.5 cm × 8 cm, dust is generated by scanning the test high-efficiency filter 70, and the scanning speed of the second dust generation port 60 is 1.5 cm / s. Keeping the dust generation amount of the aerosol dust generation device stable, the second sampling point 80 records the dust concentration downstream in real time.

[0088] As Figure 8 shown, the scanning distance is about 610 mm, the total scanning time is about 41 seconds. For the artificial leakage points made with a standard-sized injection needle of 0.7 mm, there are about 3 seconds of abnormal data during the scanning process, and the leakage points can be effectively identified.

[0089] V. Preliminary Experimental Conclusions

[0090] 1. The scheme for increasing the local dust concentration upstream of the test high-efficiency filter 70 is feasible, and the local defect points of the test high-efficiency filter 70 can be effectively identified. With the same total dust generation amount, the local dust generation scheme can increase the downstream concentration by more than 300 times.

[0091] 2. The identifiability of local defects in the dynamic process of upstream dust generation scanning is highly feasible. It can ensure abnormal data for more than 2 seconds. Verified by experiments, the local defect positions can be effectively identified.

[0092] In the present utility model, specific examples are used to elaborate on the principle and implementation manner of the present utility model. The descriptions of the above embodiments are only used to help understand the method and its core idea of the present utility model; at the same time, for those of ordinary skill in the art, according to the idea of the present utility model, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present utility model.

Claims

1. A local filtration efficiency detection device, characterized in that: It includes a scanning dust generating device, a filtering device and a sampling device. The scanning dust generating device and the sampling device are respectively arranged upstream and downstream of the filter. The filter is installed at the air inlet of the filtering device. The sampling device is located inside the filtering device. The scanning dust generating device is used to scan and move within the width range of the filter. The sampling device is used to perform real-time sampling on the air flow passing through the filter, and locate the leakage point by the abnormal increase of the sampling value.

2. The partial filtration efficiency detection device according to claim 1, characterized in that: The scanning dust generating device includes a scanning dust generating head and a scanning enclosure that penetrates through from front to back. The scanning enclosure is installed at the air inlet. The scanning dust generating head is located inside the scanning enclosure and faces the filter. The scanning dust generating head is connected with a hollow scanning connecting rod, and the end of the scanning connecting rod far away from the scanning dust generating head is an injection port.

3. The local filtration efficiency detection device according to claim 2, wherein: Rake-shaped grooves are arranged on the side of the scanning enclosure. The scanning connecting rod penetrates through the rake-shaped grooves and can move within the rake-shaped grooves. The rake-shaped grooves include a main groove for changing the scanning position longitudinally and rake teeth grooves for lateral scanning movement. The rake teeth grooves are evenly distributed on the main groove, and the main groove is communicated with the rake teeth grooves.

4. The partial filtration efficiency detection device according to claim 2, characterized in that: The scanning dust generating head adopts a scanning funnel. The inlet end of the scanning funnel is a small-diameter end, and the outlet end of the scanning funnel is a large-diameter end. The small-diameter end is connected with the scanning connecting rod, and the large-diameter end faces the filter.

5. The partial filtration efficiency detection device according to claim 1, wherein: The sampling device includes a sampling head, a conduit and a sampling instrument. The sampling head is located inside the filtering device, and the conduit connects the sampling head and the sampling instrument.

6. The local filtration efficiency detection device according to claim 5, characterized in that: The filtering device includes a first ventilation section and a second ventilation section. One end of the first ventilation section is provided with the air inlet, and the other end of the first ventilation section is connected with the second ventilation section. The inner diameter of the first ventilation section is larger than that of the second ventilation section, and the sampling head is arranged inside the second ventilation section.

7. The local filtration efficiency detection device according to claim 5, characterized in that: The sampling head includes a sampling tube, and a sampling port is arranged on the windward surface of the sampling tube.

8. The local filtration efficiency detection device according to claim 7, characterized in that: The sampling tube includes an I-shaped sampling main pipe and sampling branch pipes vertically connected to the transverse arms of the I-shaped sampling main pipe. The I-shaped sampling main pipe and the sampling branch pipes are in the same plane, and this plane is perpendicular to the air flow direction.

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