Method for detecting filtering efficiency of filter in full particle size range

Abstract

The invention discloses a method for detecting the filtering efficiency of a filter in a full particle size range, which comprises the following steps: S1, assembling a detection device, fixing a filter membrane in a filter cavity, and detecting the air tightness of the filter cavity; s2, generating dust-containing gas with fixed concentration by adopting a dust generating device; s3, inputting dust-containing gas generated by the dust generating device into the upstream of the filtering cavity; s4, detecting the number concentration of particulate matters at the upstream of the filter cavity through a filter efficiency detection unit, penetrating the dusty gas through the filter membrane, filtering the dust by the filter membrane, and detecting the number concentration of particulate matters at the downstream of the filter cavity through the filter efficiency detection unit; s5, detecting the pressure difference between the upstream of the filtering cavity and the downstream of the filtering cavity; and S6, calculating the filtering efficiency of the filter according to a corresponding formula. The comprehensive filtering performance of the polydisperse particles in a real environment can be reflected, and the actual reference value of a result is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of particulate filtration, and particularly to a method for detecting the filtration efficiency of a filter in the full particle size range. Background Art

[0002] Productive dust will be generated during the production process. The sources of productive dust are very extensive, and almost all mines and factories can generate dust during the production process. Large particle size dust will settle under the action of gravity, while small particle size dust will be suspended in the air, causing mechanical wear and being prone to dust explosion when encountering a fire source. At the same time, fine particulate matter will enter the alveolar area of the operator with breathing, causing serious harm to their health. Although in recent years, China has studied and applied a variety of dust reduction technologies, due to the technological characteristics of some operation processes, it is difficult to ensure that the dust concentration in the operation environment does not exceed the dust concentration threshold of relevant standards. Therefore, in the workplace where productive dust is generated, in order to protect the health of the operators, respiratory protection equipment needs to be worn during the operation to achieve the purpose of isolating dust.

[0003] Currently, respiratory protection equipment mainly relies on filter media filtration, and realizes the filtration and separation of dust through mechanisms such as inertial collision, interception, diffusion, gravity, and electrostatic adsorption. Currently, the detection of the filtration efficiency of filters usually calculates based on the mass concentration of particulate matter before and after filtration. Since the mass of large particle size particulate matter is usually large, therefore, the filtration efficiency detection method based on mass concentration may lead to an overestimation of the filtration efficiency of the filter for small particle size particulate matter, and it is difficult to accurately reflect the true filtration efficiency of the filter when filtering small particle size particulate matter.

[0004] Based on the above technical problems, the present invention provides a method for detecting the filtration efficiency of a filter in the full particle size range. Summary of the Invention

[0005] The object of the present invention is to provide a method for detecting the filtration efficiency of a filter in the full particle size range to solve the problems existing in the prior art.

[0006] To achieve the above object, the present invention provides the following solution: The present invention provides a method for detecting the filtration efficiency of a filter in the full particle size range, including the following steps: S1. Assemble the detection device, fix the filter membrane in the filtration chamber with a filter membrane clamp, and detect the airtightness of the filtration chamber; S2. Generate a dust-containing gas with a fixed concentration using a dust generation device; S3. Input the dust-containing gas generated by the dust generation device into the upstream of the filtration chamber; S4. Detect the particle number concentration in the upstream of the filtration chamber through a filtration efficiency detection unit. After the detection result tends to be stable, record the particle number concentration of 0.1 - 10 μm in the upstream of the filtration chamber , the dusty gas passes through the filter membrane, the dust is filtered by the filter membrane, and the number concentration of particulate matter with a size of 0.1 - 10 μm downstream of the filter cavity is detected by the filtration efficiency detection unit. ; S5. Detect the pressure difference between the upstream and downstream of the filter cavity through the pressure difference detection unit, and the waste gas is recovered and treated through the waste gas collector; S6. Calculate the filtration efficiency of the filter for particulate matter with a particle size of according to the following formula : .

[0007] According to the precise detection method for the filtration efficiency of the filter in the full particle size range provided by the present invention, in S2, the dust generation device includes: A dust bin, which is connected to the upstream of the filter cavity; An air filtration unit, which includes an air compressor and a second high-efficiency filter. The air compressor is connected to the second high-efficiency filter, and the high-efficiency filter is communicated with a first three-way valve; A first dust generation unit, which includes an aerosol generation pipeline. Both ends of the aerosol generation pipeline are respectively connected to the first three-way valve and a first three-way joint. The aerosol generation pipeline is successively connected in series with an aerosol generator and a drying pipe along the air flow direction. The first three-way joint is communicated with the dust bin through an air inlet pipe.

[0008] According to the precise detection method for the filtration efficiency of the filter in the full particle size range provided by the present invention, in S4, the filtration efficiency detection unit is respectively connected to the upstream and downstream of the filter cavity through a second three-way valve.

[0009] According to the precise detection method for the filtration efficiency of the filter in the full particle size range provided by the present invention, the filtration efficiency detection unit includes a scanning mobility particle sizer, an optical particle sizer, and a third three-way joint. The third three-way joint is connected to the scanning mobility particle sizer through a nano-scale particle detection pipeline, and the third three-way joint is connected to the optical particle sizer through a micro-scale particle detection pipeline. The third three-way joint is connected to the second three-way valve. An upstream particle detection port is opened on the upstream of the filter cavity, and a downstream particle detection port is opened on the downstream of the filter cavity. The upstream particle detection port and the downstream particle detection port are respectively connected to the second three-way valve.

[0010] According to the precise detection method for the filtration efficiency of filters within the full particle size range provided by the present invention, a dust-containing gas sampling port is provided on the dust bin. The dust-containing gas sampling port is connected to an electrostatic neutralizer through a sampling pipeline. An air inlet is provided upstream of the filtration chamber. The electrostatic neutralizer is connected to a second three-way joint. A detection air path inlet pipeline is connected between the second three-way joint and the air inlet. A bypass air path is connected between the second three-way joint and a first high-efficiency filter.

[0011] According to the precise detection method for the filtration efficiency of filters within the full particle size range provided by the present invention, in S5, a flow control system is provided between the waste gas collector and the filtration chamber. The flow control system includes a detection air path outlet pipeline. The detection air path outlet pipeline is connected to the waste gas collector. A filter filtration efficiency detection chamber air outlet is provided downstream of the filtration chamber. An air outlet pipeline is connected between the filter filtration efficiency detection chamber air outlet and the detection air path outlet pipeline. A flow regulating valve, a flow meter, and a vacuum pump are sequentially connected in series along the gas flow direction on the detection air path outlet pipeline.

[0012] According to the precise detection method for the filtration efficiency of filters within the full particle size range provided by the present invention, the dust bin and the waste gas collector are communicated through a dust-containing gas outlet pipeline.

[0013] According to the precise detection method for the filtration efficiency of filters within the full particle size range provided by the present invention, in S5, the differential pressure detection unit includes a differential pressure gauge. An upstream pressure drop detection port and a downstream pressure drop detection port are respectively provided upstream and downstream of the filtration chamber. The upstream pressure drop detection port and the downstream pressure drop detection port are respectively connected to the differential pressure gauge.

[0014] The present invention discloses the following technical effects: 1) Traditional methods mostly target single particle sizes (such as the MPPS point) or test in sub-particle size segments, while this method synchronously detects in the full particle size range of 0.1 - 10 μm, covering the complete range from sub-micron to fine particles.

[0015] 2) The present invention can identify the filtration efficiency of filters for the most difficult-to-capture particle sizes, avoiding the misunderstanding of "locally efficient but overall inefficient".

[0016] 3) The present invention can reflect the comprehensive filtration performance of multi-dispersed particles in the real environment, enhancing the practical reference value of the results.

[0017] 4) The dust generation device in the present invention can generate dust-containing gases with different compositions, adapting to various industrial scenarios.

[0018] 5) The filter membrane clamp design supports rapid replacement of the filter membrane, enabling efficient testing in multiple batches. Description of the Drawings

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0020] Figure 1 It is a flowchart of a method for detecting the filtration efficiency of a filter in the full particle size range.

[0021] Among them, 1. Air compressor; 2. Second high-efficiency filter; 3. First three-way valve; 4. Aerosol generation pipeline; 5. Aerosol generator; 6. Drying pipe; 7. Dust generator; 8. Dust generation pipeline; 9. First three-way joint 1; 10. Air inlet pipe; 11. Dust bin; 12. Dust-containing air outflow pipeline; 13. Exhaust gas collector; 14. Dust-containing air sampling port; 15. Sampling pipeline; 16. Electrostatic neutralizer; 17. Detection gas path inlet pipeline; 18. Air inlet; 19. Filter cavity; 20. Filter membrane clamp; 21. Outlet of the filter efficiency detection cavity of the filter; 22. Outlet pipeline; 23. Upstream pressure drop detection port; 24. Downstream pressure drop detection port; 25. Upstream particulate matter detection port; 26. Downstream particulate matter detection port; 27. Differential pressure gauge; 28. Second three-way valve; 29. Third three-way joint; 30. Nanoscale particulate matter detection pipeline; 31. Micron-scale particulate matter detection pipeline; 32. Scanning mobility particle sizer; 33. Optical particle sizer; 34. First high-efficiency filter; 35. Branch gas path; 36. Second three-way joint; 37. Flow regulating valve; 38. Flow meter; 39. Vacuum pump; 40. Detection gas path outlet pipeline. Specific embodiments

[0022] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0023] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the drawings and specific embodiments.

[0024] Refer to Figure 1 , the present invention provides a method for detecting the filtration efficiency of a filter in the full particle size range, including the following steps: S1. Assemble the detection device, fix the filter membrane in the filter cavity 19 using the filter membrane clamp 20, and detect the airtightness of the filter cavity 19; S2. Generate dust-containing gas with a fixed concentration using a dust generation device; S3. Input the dust-containing gas generated by the dust generation device upstream of the filter chamber 19; S4. Detect the particle number concentration upstream of the filter chamber 19 through the filtration efficiency detection unit. After the detection result tends to be stable, record the particle number concentration of 0.1 - 10 μm particles inside the upstream of the filter chamber 19 , the dust-containing gas passes through the filter membrane, and the dust is filtered by the filter membrane. Detect the particle number concentration of 0.1 - 10 μm particles downstream of the filter chamber through the filtration efficiency detection unit ; S5. Detect the pressure difference between the upstream and downstream of the filter chamber 19 through the pressure difference detection unit, and the waste gas is recovered and treated through the waste gas collector 13; S6. Calculate the filtration efficiency of the filter for particles with a particle size of according to the following formula : .

[0025] The filter membrane clamp 20 refers to a device that fixes the filter membrane and ensures the airtightness of the detection chamber. Specifically, it can be realized by using a metal clamp with a sealing ring to prevent the leakage of unfiltered gas from affecting the detection accuracy. The dust generation device refers to a generation system that can stably output aerosol with a target concentration. Specifically, it can be realized by combining multi-stage filtration and an aerosol generator 5 to ensure the concentration stability of the test particles. The filtration efficiency detection unit refers to a combination of instruments that can count the number of particles by particle size segment. Specifically, it can be realized by connecting an electrical mobility analyzer and an optical counter in parallel, covering the detection ranges of nano-scale and micron-scale particle sizes respectively. The pressure difference detection unit refers to a device that measures the filtration resistance. Specifically, it can be realized by using a high-precision pressure difference sensor to reflect the air permeability of the filter membrane under the actual use state. The waste gas collector 13 refers to a device that treats the test exhaust gas. Specifically, it can be realized by combining a bag filter and an activated carbon adsorber, which complies with the laboratory safety specifications.

[0026] Specifically, the airtightness verification of the detection device can ensure that the gas path completely passes through the filter membrane during the test. The stability of the dust-containing gas concentration is a prerequisite for obtaining reliable detection results, which is achieved by precisely controlling the aerosol generation parameters. The synchronous detection of the upstream and downstream particle number concentrations needs to be carried out under a dynamic equilibrium state. When the fluctuation range of the detection value is less than 5%, it is determined to be a stable state. The pressure difference measurement data can assist in judging the clogging situation of the filter membrane. When the pressure difference exceeds the set threshold, the test is automatically terminated. The efficiency calculation formula uses a segmented integration method to calculate the filtration efficiency for each particle size interval separately, and finally generates a complete efficiency-particle size relationship curve.

[0027] With such a design, traditional methods can only obtain the overall filtration efficiency value, while this method can be accurate to the efficiency value at each particle size point. Due to the large contribution of large particle size particles, the mass concentration method may yield a filtration efficiency of 90%, while the actual filtration efficiency of small particle size particles may be less than 70%. Through number concentration detection, this solution can accurately identify the efficiency lowland in the small particle size range, providing a clear direction for filter media improvement.

[0028] Through the above technical solution, this application has achieved precise mapping of the filtration efficiency in the full particle size range, and the test results can distinguish the filtration performance differences of particulate matter with different particle sizes. This method can identify the efficiency weak points that cannot be found by traditional detection methods, providing multi-dimensional data support for the selection of respiratory protection equipment and effectively avoiding health risks caused by insufficient filtration of small particle size particles.

[0029] This application further proposes a dust generation device, which includes a dust bin 11, an air filtration unit, and a first dust generation unit; the dust bin 11 is connected to the upstream of the filtration cavity 19; the air filtration unit includes an air compressor 1 and a second high-efficiency filter 2, the air compressor 1 is connected to the second high-efficiency filter 2, and the high-efficiency filter is communicated with a first three-way valve 3; the first dust generation unit includes an aerosol generation pipeline 4, both ends of the aerosol generation pipeline 4 are respectively connected to the first three-way valve 3 and a first three-way joint, and the aerosol generation pipeline 4 is successively connected in series with an aerosol generator 5 and a drying pipe 6 along the air flow direction, and the first three-way joint is communicated with the dust bin 11 through an air inlet pipe 10.

[0030] Among them, the dust bin 11 refers to a closed container for storing and transporting dust-containing gas, which can be specifically made of stainless steel, and a stirring device can be arranged inside it to prevent dust settlement. The air compressor 1 refers to a device that compresses and transports ambient air to the filtration unit, which can be specifically realized by an oil-free screw compressor and is used to provide an oil-free clean air source. The second high-efficiency filter 2 refers to a device for filtering compressed air, which can be specifically realized by a HEPA filter and can remove residual particulate matter in the compressed air to ensure gas purity. The aerosol generator 5 refers to a device for generating particulate matter with a specific particle size, which can be specifically realized by a collision type or ultrasonic type generator and is used to generate aerosol as test particulate matter. The drying pipe 6 refers to a tubular structure for drying the aerosol, and silica gel or molecular sieve can be specifically used as a desiccant to remove moisture in the aerosol to avoid caking.

[0031] Specifically, the compressed air output by the air compressor 1 enters the first three-way valve 3 after being purified by the second high-efficiency filter 2. One stream of air passes through the aerosol generator 5 to generate aerosol, and then the moisture is removed through the drying pipe 6 to form a stable aerosol stream. This aerosol stream is mixed with another stream of clean air at the first three-way joint to form a dust-containing gas with controllable concentration, and is transported to the dust bin 11 through the intake pipe 10. The dust-containing gas in the dust bin 11 is then introduced upstream of the filter cavity 19 to provide a standardized test gas source for the filtration efficiency detection.

[0032] With such a design, traditional dust-producing devices usually directly mix dust and air through a single gas path, which easily leads to fluctuations in gas concentration or particle agglomeration. In this solution, by independently setting the aerosol generation and air purification units, combining the drying treatment and the multi-path mixing structure, the aerosol concentration and particle size distribution can be precisely controlled. At the same time, the introduction of the high-efficiency filter effectively avoids the interference of impurities in the compressed air on the test results.

[0033] Through the above technical solutions, this application solves the problems of unstable gas concentration and uneven dispersion of particulate matter during the dust production process, and realizes the precise preparation of dust-containing gas through modular design. This device can generate a uniform aerosol that meets the test requirements, providing reliable input conditions for the subsequent filtration efficiency detection, thereby ensuring the accuracy and repeatability of the detection data.

[0034] This application further proposes that the filtration efficiency detection unit is connected to the upstream and downstream of the filter cavity 19 through the second three-way valve 28 respectively.

[0035] Among them, the second three-way valve 28 refers to a valve device with three channels, which can specifically be realized by a three-way ball valve made of metal or engineering plastic. Its function is to select and connect the upstream or downstream detection gas path by switching the valve state. The filtration efficiency detection unit refers to a combination of devices used to measure the particulate matter concentration and particle size distribution, which can specifically be realized by integrating detection instruments such as a particulate matter size spectrometer. Its function is to collect and analyze the particulate matter data upstream and downstream of the filter cavity 19.

[0036] Specifically, during the filtration efficiency detection process, the second three-way valve 28 is connected to the upstream particulate matter detection port 25 upstream of the filter cavity 19 and the downstream particulate matter detection port 26 downstream through pipelines respectively. When it is necessary to detect the upstream particulate matter concentration, the second three-way valve 28 switches to the path connecting the upstream detection port and the filtration efficiency detection unit; after the data is stable, the valve state is switched again to connect the downstream detection port and the detection unit. Through this switching method, the same set of detection equipment can obtain the particulate matter concentration data upstream and downstream respectively, avoiding the systematic error caused by parallel detection of multiple devices.

[0037] With such a design, traditional detection methods usually adopt upstream and downstream independent detection devices with fixed connections, which not only increases the equipment cost but also may affect the result accuracy due to the measurement accuracy differences between different devices. This solution combines a single detection unit with a valve switching design, which not only simplifies the detection process but also ensures data consistency, significantly improving the calculation accuracy of the filtration efficiency in the full particle size range.

[0038] Through the above technical solution, the present application realizes high-precision synchronous detection of the particulate matter concentrations upstream and downstream of the filtration chamber 19, effectively solving the calculation deviation problem caused by the particle size distribution difference in the traditional mass concentration method, and providing a reliable data basis for evaluating the true filtration efficiency of the filter for particulate matter of different particle sizes.

[0039] The present application further proposes that the filtration efficiency detection unit includes a scanning mobility particle sizer 32, an optical particle sizer 33, and a third three-way joint 29. The third three-way joint 29 is connected to the scanning mobility particle sizer 32 through a nano-scale particulate matter detection pipeline 30, and the third three-way joint 29 is connected to the optical particle sizer 33 through a micro-scale particulate matter detection pipeline 31. The third three-way joint 29 is connected to the second three-way valve 28. An upstream particulate matter detection port 25 is opened on the upstream of the filtration chamber 19, and a downstream particulate matter detection port 26 is opened on the downstream of the filtration chamber 19. The upstream particulate matter detection port 25 and the downstream particulate matter detection port 26 are respectively connected to the second three-way valve 28.

[0040] Among them, the scanning mobility particle sizer 32 refers to a device for measuring the number concentration of nano-scale particulate matter based on the principle of electrophoresis migration. Specifically, a differential mobility analyzer can be used. This device classifies charged particles in a migration tube by applying an electric field and obtains particle size distribution data in cooperation with a particle counter. The optical particle sizer 33 refers to a device for measuring the number concentration of micro-scale particulate matter based on the principle of light scattering. Specifically, a laser scattering particle counter can be used. This device inversely calculates the particle size information by recording the light scattering intensity when the particles pass through the laser beam. The third three-way joint 29 refers to a gas path connector with three interfaces. Specifically, a T-shaped metal pipe fitting can be used to divert the upstream or downstream gas path to different detection devices. The nano-scale particulate matter detection pipeline 30 refers to a pipeline for transporting aerosol containing nano-scale particles. Specifically, a conductive silica gel tube can be used to prevent particle loss caused by electrostatic adsorption. The micro-scale particulate matter detection pipeline 31 refers to a pipeline for transporting aerosol containing micro-scale particles. Specifically, a polytetrafluoroethylene tube can be used to avoid inertial deposition of particles on the pipe wall.

[0041] Specifically, the second three-way valve 28 first switches to the upstream detection port. The dusty gas is divided into two paths through the third three-way joint 29: the nanoscale particles enter the scanning electrical mobility particle sizer to complete the number concentration detection in the particle size range of 0.1 - 1 μm, and the micron-scale particles enter the optical particle sizer to complete the number concentration detection in the particle size range of 1 - 10 μm. After the upstream concentration stabilizes, the second three-way valve 28 switches to the downstream detection port, and the above-mentioned particle size-separated detection process is repeated. By respectively obtaining the number concentration data of each particle size range upstream and downstream, the fractional filtration efficiency of the filter in the full particle size range can be accurately calculated.

[0042] With such a design, the traditional method only evaluates the filtration efficiency through the change in mass concentration. However, due to the excessive proportion of large particle size particles in the total mass, it leads to misjudgment of the filtration efficiency of small particle sizes. This solution completely eliminates the particle size deviation problem of the mass concentration method through particle size-separated number concentration detection. At the same time, dedicated detection pipelines are used to separately transport particles of different particle sizes, avoiding cross-interference of particles of different particle sizes during transportation.

[0043] Through the above technical solution, this application can accurately obtain the filtration efficiency data of particles of each particle size in the range of 0.1 - 10 μm, avoiding errors caused by the mass concentration detection method. For example, when filtering nanoscale particles, even if their mass proportion is less than 0.1%, the filtration efficiency can still be accurately evaluated through the change in number concentration, which is crucial for evaluating the PM0.3 filtration performance of protective masks.

[0044] This application further proposes that a dusty gas sampling port 14 is opened on the dust bin 11. The dusty gas sampling port 14 is connected to the static eliminator 16 through a sampling pipeline 15. An air inlet 18 is opened upstream of the filter cavity 19. The static eliminator 16 is connected to the second three-way joint 36. A detection gas path air inlet pipeline 17 is connected between the second three-way joint 36 and the air inlet 18. A bypass gas path 35 is connected between the second three-way joint 36 and the first high-efficiency filter 34.

[0045] Among them, the dusty gas sampling port 14 refers to a channel opened on the surface of the dust bin 11 for extracting samples of dusty gas, which can be specifically realized by using a valve structure with adjustable opening to control the sampling flow rate.

[0046] Among them, the static eliminator 16 refers to a device that eliminates the surface charge of particulate matter by releasing ions, which can be specifically realized by using a radioactive source or a corona discharge device to avoid the interference of the detection results caused by the aggregation of charged particulate matter due to electrostatic force.

[0047] Among them, the second three-way joint 36 refers to a pipe fitting with three interfaces, which can be specifically realized by using a three-way pipe structure made of metal or plastic to switch the connection state between the detection gas path and the bypass gas path 35.

[0048] Among them, the bypass air passage 35 refers to an auxiliary air flow passage that bypasses the filter cavity 19, which can be specifically implemented by connecting an independent pipeline to the first high-efficiency filter 34, and is used to maintain the system pressure balance and filter particulate matter in the bypass gas.

[0049] Specifically, before the dust-containing gas enters the filter cavity 19, a part of the air flow is extracted through the dust-containing air flow sampling port 14 of the dust bin 11, and is transported through the sampling pipeline 15 to the static eliminator 16 for charge elimination treatment. The treated air flow is divided by the second three-way joint 36. One part enters the detection air passage inlet pipeline 17 and is introduced into the air inlet 18 upstream of the filter cavity 19, and the other part is discharged after being purified by the first high-efficiency filter 34 through the bypass air passage 35. By adjusting the valve opening of the second three-way joint 36, the air flow ratio entering the detection air passage and the bypass air passage 35 can be controlled, so as to ensure the uniformity of the particulate matter concentration in the detection air passage while maintaining the stable operation of the system.

[0050] With such a design, the existing detection system usually directly collects the untreated dust-containing gas without considering the influence of the particulate matter charge effect on the detection accuracy. And this solution can eliminate the surface charge of the particulate matter by introducing the static eliminator 16, avoiding the measurement deviation of the particle size distribution caused by electrostatic adsorption. At the same time, the setting of the bypass air passage 35 effectively balances the system pressure fluctuation and solves the problem of unstable particulate matter concentration caused by sudden flow changes in traditional single-air-passage detection.

[0051] Through the above technical solutions, this application can improve the representativeness of the dust-containing gas sample, avoid detection errors caused by charged particulate matter, and at the same time maintain the stability of the detection environment through shunt control, thereby improving the accuracy of the filter efficiency detection result.

[0052] This application further proposes to set a flow control system between the waste gas collector 13 and the filter cavity 19. The flow control system includes a detection air passage outlet pipeline 40, the detection air passage outlet pipeline 40 is connected to the waste gas collector 13, a filter efficiency detection cavity air outlet 21 is opened downstream of the filter cavity 19, and the filter efficiency detection cavity air outlet 21 and the detection air passage outlet pipeline 40 are connected through an air outlet pipeline 22. A flow regulating valve 37, a flow meter 38, and a vacuum pump 39 are sequentially connected in series along the gas flow direction on the detection air passage outlet pipeline 40.

[0053] Among them, the detection air passage outlet pipeline 40 refers to a pipeline used to guide the flow of the filtered waste gas, which can be specifically implemented by using corrosion-resistant metal or plastic materials, and its function is to form a waste gas transmission channel.

[0054] Among them, the flow regulating valve 37 refers to a device that can adjust the gas flow, which can be specifically implemented by using a manual or electric valve, and is used to control the gas flow rate in the detection air passage.

[0055] Among them, the flowmeter 38 refers to an instrument for measuring the volumetric flow rate of gas, and specifically, a vortex street type or thermal type flow sensor can be used to achieve it, which is used to monitor the exhaust gas flow data in real time.

[0056] Among them, the vacuum pump 39 refers to a gas conveying device that generates negative pressure, and specifically, a centrifugal type or rotary vane type vacuum pump 39 can be used to achieve it, which is used to maintain a stable pressure difference environment in the detection gas path.

[0057] Specifically, during the detection process, the exhaust gas enters the outlet air pipe 40 of the detection gas path from the air outlet downstream of the filter cavity 19, and successively flows through the flow regulating valve 37, the flowmeter 38, and the vacuum pump 39. The flow regulating valve 37 controls the gas flow velocity through the opening degree adjustment, the flowmeter 38 synchronously monitors the actual flow value, and the vacuum pump 39 maintains a constant negative pressure in the pipeline through the suction effect. The three work together to keep the gas flow in the detection gas path dynamically stable, avoiding the detection error of the particulate matter concentration caused by the flow fluctuation.

[0058] With such a design, the traditional filtration efficiency detection system usually lacks a closed-loop flow control link, and only extracts gas through a fixed-power device, unable to adjust the flow rate in real time. However, in this solution, by connecting the flow regulating valve 37, the flowmeter 38, and the vacuum pump 39 in series, a closed-loop feedback control is formed, which can dynamically optimize the gas flow velocity during the detection process to ensure that the upstream and downstream particulate matter concentrations are detected under the same flow rate benchmark.

[0059] Through the above technical solution, this application effectively solves the problem of the filtration efficiency calculation error caused by the flow fluctuation in the traditional detection method. By precisely controlling the gas flow in the detection gas path, the change in the particulate matter distribution caused by the unstable flow velocity is avoided, thereby improving the accuracy and repeatability of the filtration efficiency detection results in the full particle size range.

[0060] This application further proposes a technical solution in which the dust bin 11 and the exhaust gas collector 13 are connected through the dust-containing gas outlet air pipe 12.

[0061] Among them, the dust bin 11 refers to a container for storing and supplying dust-containing gas. Specifically, a sealed bin body can be made of metal or polymer material, and a stirring device can be arranged inside it to achieve uniform dispersion of the dust. This structure is used to provide a dust-containing gas flow with a stable concentration for the detection system.

[0062] Among them, the exhaust gas collector 13 refers to a device for recovering and treating dust-containing gas. Specifically, a negative pressure adsorption or filtration type purification device can be used, and the exhaust gas is treated through physical adsorption or chemical decomposition methods. This device is used to prevent the dust generated during the detection process from spreading to the external environment.

[0063] Among them, the dust-containing air outlet pipeline 12 refers to the pipeline connecting the dust bin 11 and the waste gas collector 13, which can specifically adopt a corrosion-resistant metal pipe or a flexible hose, and achieve airtight connection through flanges or clamps. This pipeline is used to form a closed air flow circulation path to avoid dust leakage.

[0064] Specifically, the dust-containing air outlet pipeline 12 directly connects the dust bin 11 and the waste gas collector 13, so that the dust-containing gas not intercepted by the filter membrane during the detection process can be directly transported to the waste gas collector 13 for purification treatment. During the air flow circulation process, the connection port of the pipeline to the dust bin 11 can be set at the bottom of the bin body to facilitate the efficient output of the dust-containing gas; a flow control valve can be installed at the inlet of the waste gas collector 13 to adjust the air flow pressure in the pipeline. Through the design of this closed path, dust is restricted within the closed system during transportation, reducing the risk of environmental pollution to the outside.

[0065] With such a design, in the traditional detection system, the dust bin 11 and the waste gas collector 13 are usually independent units, and the waste gas needs to be transported through an open space or complex pipelines, which easily leads to secondary dust diffusion. This solution forms a closed circulation path through the pipeline structure directly connecting the two, which can effectively avoid the escape of particulate matter during the detection process and reduce the interference of external air flow fluctuations on the detection stability.

[0066] Through the above technical solution, the present application can achieve closed-loop control of the dust air flow in the detection system, and solve the detection error problem caused by dust diffusion in the open system. The pipeline connection method simplifies the waste gas treatment process, enables the unfiltered particulate matter to directly enter the collector, avoids the operator from being exposed to the dust environment, and reduces the explosion risk caused by the residue of dust inside the equipment.

[0067] The present application further proposes a precise detection method for the filtration efficiency of filters in the full particle size range. When detecting the pressure difference between the upstream and downstream of the filtration cavity 19, the pressure difference detection unit includes a differential pressure gauge 27. Upstream and downstream of the filtration cavity 19, an upstream pressure drop detection port 23 and a downstream pressure drop detection port 24 are respectively opened, and the upstream pressure drop detection port 23 and the downstream pressure drop detection port 24 are respectively connected to the differential pressure gauge 27.

[0068] Among them, the differential pressure gauge 27 refers to an instrument used to measure the pressure difference between two points of a fluid, which can specifically be implemented by a digital differential pressure sensor or a mechanical U-shaped tube differential pressure gauge. By real-time monitoring of the pressure difference between the upstream and downstream, it can reflect the resistance change of the filter membrane during the filtration process.

[0069] Among them, the upstream pressure drop detection port 23 and the downstream pressure drop detection port 24 refer to the interfaces opened on the filtration cavity 19, which can specifically be implemented by a tubular structure with a sealing thread. By connecting the two detection ports to the two ends of the differential pressure gauge 27 respectively, it ensures the accurate transmission of the pressure signal to the detection unit.

[0070] Specifically, pressure drop detection ports are respectively arranged upstream and downstream of the filtering cavity 19. The two detection ports are directly connected to the differential pressure gauge 27 through pipelines to form a complete differential pressure detection loop. When the dust-containing gas flows through the filter membrane, due to the interception of particulate matter by the filter membrane, a pressure difference will be formed between the upstream and the downstream. The differential pressure gauge 27 detects the pressure difference between the two detection ports and outputs the pressure drop data in real time, providing a basis for evaluating the filtering resistance of the filter membrane.

[0071] With such a design, the existing differential pressure detection methods usually rely on a single measurement point or indirectly calculate the pressure loss, and cannot directly reflect the actual pressure drop on both sides of the filter membrane. This solution can eliminate measurement errors and ensure the accuracy of differential pressure data by setting independent detection ports at both ends of the filtering cavity 19 and connecting them to the differential pressure gauge 27.

[0072] Through the above technical solution, this application can accurately measure the dynamic pressure drop change during the filtering process, provide key parameters for evaluating the comprehensive performance of the filter, avoid misjudgment of the filtering efficiency caused by differential pressure measurement deviation, and thus improve the reliability of the detection results.

[0073] This application further proposes a precise detection method for the filtering efficiency of the filter in the full particle size range. The differential pressure detection unit includes a differential pressure gauge 27. An upstream pressure drop detection port 23 and a downstream pressure drop detection port 24 are respectively opened upstream and downstream of the filtering cavity 19. The upstream pressure drop detection port 23 and the downstream pressure drop detection port 24 are respectively connected to the differential pressure gauge 27.

[0074] Among them, the differential pressure gauge 27 refers to a device used to measure the pressure difference before and after the gas flows through the filter membrane. Specifically, it can be implemented by a digital micro differential pressure sensor. Its range can be set, for example, to 0 - 5000 Pa, and the accuracy can reach, for example, ±1 Pa, thereby capturing the dynamic pressure drop change during the filtering process in real time.

[0075] Among them, the upstream pressure drop detection port 23 refers to an opening structure arranged in the upstream area of the filtering cavity 19. Specifically, it can be implemented by a metal pipe joint with an inner diameter of 3 - 5 mm. Its installation position can be, for example, 50 - 100 mm away from the holding position of the filter membrane clip 20 to avoid the airflow disturbance area.

[0076] Among them, the downstream pressure drop detection port 24 refers to an opening structure arranged in the downstream area of the filtering cavity 19. Its structural dimensions can be, for example, symmetrically arranged with the upstream detection port. Its installation position can be, for example, 80 - 120 mm away from the downstream surface of the filter membrane to ensure the representativeness of the measurement data.

[0077] Specifically, during the filtration efficiency detection process, the pressure drop signal generated when the dusty gas passes through the filter membrane is conducted to the differential pressure gauge 27 through the upstream pressure drop detection port 23 and the downstream pressure drop detection port 24 respectively. By detecting the pressure difference at both ends, the differential pressure gauge 27 can synchronously reflect the actual working state of the filter membrane during the filtration process. Further, the pressure difference data can be correlated with the particulate matter number concentration detection results for evaluating the resistance characteristics of the filter membrane when filtering particulate matter of different particle sizes.

[0078] In some specific embodiments, the connecting pipeline of the differential pressure gauge 27 can be configured with damping elements, such as capillary tubes or buffer cavities, and its length can be, for example, 200 - 300 mm, for eliminating the interference of airflow pulsation on pressure measurement. The opening position of the detection port can avoid the bending section of the filtration cavity 19, for example, select the middle area of the straight pipe section to ensure the stability of the measurement data.

[0079] Designed in this way, traditional filtration efficiency detection often ignores the dynamic monitoring of differential pressure or only uses a single detection point to estimate the pressure drop value. This solution realizes the accurate in-situ measurement of filtration resistance by symmetrically arranging dedicated detection ports upstream and downstream of the filtration cavity 19 and configuring a high-precision differential pressure gauge 27. This design can effectively avoid the distortion of pressure drop data caused by the deviation of the detection port position or the insufficient accuracy of the sensor.

[0080] Through the above technical solutions, this application can accurately capture the real-time pressure drop changes during the operation of the filter, providing key parameters for evaluating the comprehensive performance of the filter membrane. This data can be cross-validated with the particulate matter number concentration detection results to assist in identifying the blocking state of the filter membrane when filtering particulate matter of different particle sizes, thereby improving the reliability and accuracy of the filtration efficiency detection results.

[0081] This application further proposes that the differential pressure detection unit includes a differential pressure gauge 27, and an upstream pressure drop detection port 23 and a downstream pressure drop detection port 24 are respectively opened upstream and downstream of the filtration cavity 19, and the upstream pressure drop detection port 23 and the downstream pressure drop detection port 24 are respectively connected to the differential pressure gauge 27.

[0082] Among them, the differential pressure gauge 27 refers to a device used to measure the pressure change before and after the gas flows through the filtration cavity 19, and specifically can be implemented by a diaphragm differential pressure sensor, and real-time differential pressure data is obtained by connecting the upstream and downstream pressure interfaces. The upstream pressure drop detection port 23 refers to an opening structure arranged on the upstream side wall of the filtration cavity 19, and specifically can be implemented by a metal pipe joint with a sealing ring, for conducting the upstream gas pressure to the differential pressure gauge 27. The downstream pressure drop detection port 24 refers to an opening structure arranged on the downstream side wall of the filtration cavity 19, and specifically can adopt an interface form symmetric to the upstream detection port, and forms a closed-loop detection circuit with the differential pressure gauge 27 through a pressure guiding pipeline.

[0083] Specifically, the differential pressure detection unit captures the gas pressure signals upstream and downstream of the filter cavity 19 through two symmetrically arranged detection ports respectively, and the differential pressure gauge 27 converts the pressure difference between the two ports into an electrical signal for output. During the process of dusty gas passing through the filter membrane, as particulate matter accumulates on the surface of the filter membrane, the differential pressure between upstream and downstream will gradually increase, and the data output by the differential pressure gauge 27 can reflect the degree of filter membrane blockage in real time. During the detection process, the differential pressure data and the particulate matter concentration data are collected synchronously to form a comprehensive evaluation of the filter performance.

[0084] With such a design, traditional filter efficiency detection methods usually only focus on the change in particulate matter concentration and ignore the influence of differential pressure parameters on the filtration state. By adding a differential pressure detection function, this solution can directly obtain the filter membrane pressure drop data while detecting the filtration efficiency, realizing dual monitoring of filtration performance and resistance.

[0085] Through the above technical solution, this application solves the technical defect that the degree of filter membrane blockage cannot be evaluated in traditional detection. The differential pressure data can assist in judging whether the filter is in a normal working state, avoid detection errors caused by excessive blockage of the filter membrane, and ensure the credibility of the filtration efficiency detection result.

[0086] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0087] The above-described embodiments are only descriptions of the preferred embodiments of the present invention and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solution of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A precise detection method for the filtration efficiency of a filter within the full particle size range, characterized in that, The steps include the following: S1. Assemble the detection device, fix the filter membrane in the filter cavity (19) using a filter membrane clamp (20), and detect the airtightness of the filter cavity (19). S2. Generate a dust-containing gas with a fixed concentration using a dust generation device. S3. Input the dust-containing gas generated by the dust generation device into the upstream of the filter cavity (19). S4. Detect the particulate matter number concentration upstream of the filtration cavity (19) through the filtration efficiency detection unit. After the detection result tends to be stable, record the particulate matter number concentration of 0.1 - 10 μm inside the upstream of the filtration cavity (19). , The dust-containing gas passes through the filter membrane, and the dust is filtered by the filter membrane. Detect the particulate matter number concentration of 0.1 - 10 μm downstream of the filtration cavity (19) through the filtration efficiency detection unit. ; S5. Detect the pressure difference between the upstream and downstream of the filter cavity (19) through a pressure difference detection unit, and recover and treat the waste gas through a waste gas collector (13). S6. Calculate the filtration efficiency of the filter for particulate matter with a particle size of as follows : 。 2. The precise detection method for the filtration efficiency of a filter within the full particle size range according to claim 1, characterized in that, In S2, the dust generation device includes: A dust bin (11), which is connected to the upstream of the filter cavity (19). An air filtration unit, which includes an air compressor (1) and a second high-efficiency filter (2). The air compressor (1) is connected to the second high-efficiency filter (2), and the high-efficiency filter is communicated with a first three-way valve (3). A first dust generation unit, which includes an aerosol generation pipeline (4). The two ends of the aerosol generation pipeline (4) are respectively connected to the first three-way valve (3) and a first three-way joint. Along the air flow direction, an aerosol generator (5) and a drying pipe (6) are sequentially connected in series on the aerosol generation pipeline (4). The first three-way joint is communicated with the dust bin (11) through an air inlet pipe (10).

3. The precise detection method for the filtration efficiency of a filter within the full particle size range according to claim 1, characterized in that, In S4, the filter efficiency detection unit is respectively connected to the upstream and downstream of the filter cavity (19) through a second three-way valve (28).

4. The precise detection method for the filtration efficiency of a filter within the full particle size range according to claim 3, characterized in that, The filter efficiency detection unit includes a scanning mobility particle sizer (32), an optical particle sizer (33), and a third three-way joint (29). The third three-way joint (29) is connected to the scanning mobility particle sizer (32) through a nano-scale particle detection pipeline (30). The third three-way joint (29) is connected to the optical particle sizer (33) through a micro-scale particle detection pipeline (31). The third three-way joint (29) is connected to the second three-way valve (28). An upstream particle detection port (25) is opened on the upstream of the filter cavity (19), and a downstream particle detection port (26) is opened on the downstream of the filter cavity (19). The upstream particle detection port (25) and the downstream particle detection port (26) are respectively connected to the second three-way valve (28).

5. The precise detection method for the filtration efficiency of a filter within the full particle size range according to claim 2, wherein, A dust-containing air sampling port (14) is opened on the dust bin (11). The dust-containing air sampling port (14) is connected to an electrostatic neutralizer (16) through a sampling pipeline (15). An air inlet (18) is opened on the upstream of the filter cavity (19). The electrostatic neutralizer (16) is connected to a second three-way joint (36). The second three-way joint (36) is connected to the air inlet (18) through a detection air path inlet pipeline (17). The second three-way joint (36) is connected to a first high-efficiency filter (34) through a bypass air path (35).

6. The precise detection method for the filtration efficiency of a filter within the full particle size range according to claim 1, characterized in that, In S5, a flow control system is provided between the exhaust gas collector (13) and the filtration chamber (19). The flow control system includes a detection air path outlet pipe (40). The detection air path outlet pipe (40) is connected to the exhaust gas collector (13). An air outlet (21) for detecting the filtration efficiency of the filter is provided downstream of the filtration chamber (19). The air outlet (21) for detecting the filtration efficiency of the filter is connected to the detection air path outlet pipe (40) through an outlet pipe (22). A flow control valve (37), a flow meter (38), and a vacuum pump (39) are connected in series along the gas flow direction on the detection air path outlet pipe (40).

7. The precise detection method for the filtration efficiency of a filter within the full particle size range according to claim 2, wherein The dust bin (11) is communicated with the exhaust gas collector (13) through a dust-containing gas outlet pipe (12).

8. The precise detection method for the filtration efficiency of a filter within the full particle size range according to claim 1, characterized in that, In S5, the differential pressure detection unit includes a differential pressure gauge (27). An upstream pressure drop detection port (23) and a downstream pressure drop detection port (24) are respectively provided upstream and downstream of the filtration chamber (19). The upstream pressure drop detection port (23) and the downstream pressure drop detection port (24) are respectively connected to the differential pressure gauge (27).

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