A method and device for monitoring and early warning of a composite parameter of an air sampling filter of an air suction type

Abstract

The application discloses a kind of methods and devices for monitoring and early warning of air sampling filter cotton composite parameters of air-breathing type, and relates to the technical field of air-breathing type air sampling, and its technical solution points are: obtaining the steady-state pressure difference by calculating upstream and downstream air pressure of filter cotton;Obtain the pulsatile signal and extract the pulsatile frequency and pulsatile amplitude by frequency spectrum analysis;According to the change amount of steady-state pressure difference, pulsatile frequency and pulsatile amplitude relative to their respective reference values, distinguish normal state, fiber aging early warning, dust blockage fault and filter cotton damage fault through fault discrimination matrix;According to the classification early warning signal output by the distinguishing result.The application realizes the early warning of filter cotton state and the accurate distinction of fault type by fusing three characteristic parameters of steady-state pressure difference, pulsatile frequency and pulsatile amplitude, and simultaneously realizes long-term stable operation in high dust environment through the structure design of stable pressure dustproof buffer gas cavity and polytetrafluoroethylene microporous flow filter membrane.

Description

Technical Field

[0001] This invention relates to the field of aspirating air sampling technology, and more specifically, to a method and device for monitoring and early warning of composite parameters of aspirating air sampling filter cotton. Background Technology

[0002] Air-breathing sampling systems are widely used in early fire detection and ambient air quality monitoring. This system uses an air pump to draw air from the protected area through sampling pipelines and delivers it to the detector unit for analysis. An external filter, a key component at the sampling pipeline inlet, intercepts larger dust particles in the air, preventing them from entering the detector and interfering with smoke or gas detection. During use, the filter gradually accumulates dust and becomes clogged, or experiences fiber aging and localized damage. Failure to replace it promptly will obstruct the sampling airflow, reduce detector sensitivity, and in severe cases, even create blind spots in fire detection.

[0003] Currently, monitoring the condition of filter cotton mainly relies on a single steady-state differential pressure method, which involves installing differential pressure sensors on both sides of the filter cotton and triggering an alarm when the differential pressure exceeds a preset threshold. However, the above-mentioned existing technology, which relies on only a single differential pressure dimension for judgment, has the following shortcomings: First, differential pressure changes are not sensitive to minor damage to the filter cotton and early fiber aging. An alarm is only triggered when the filter cotton is severely clogged or has large-area damage causing a significant change in air pressure, resulting in a serious alarm lag. Second, a single differential pressure cannot distinguish between three different types of fault states: aging, clogging, and damage. Maintenance personnel cannot predict the cause of the fault and the required spare parts, leading to low maintenance efficiency. Third, in high-dust environments, the differential pressure sensor probe is directly exposed to the dusty airflow, making it susceptible to dust contamination and measurement drift. Frequent shutdowns for calibration are required, affecting the long-term operational stability of the system.

[0004] Therefore, researching and designing a method and device for monitoring and early warning of composite parameters of aspirating air sampling filter cotton that can overcome the above-mentioned defects is an urgent problem to be solved. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a method and device for monitoring and early warning of composite parameters of aspirating air sampling filter cotton. By integrating characteristic parameters of three dimensions—steady-state pressure difference, airflow pulsation frequency, and pulsation amplitude—a fault discrimination matrix is ​​constructed to accurately identify and classify filter cotton aging, clogging, and damage faults, overcoming the shortcomings of existing technologies such as alarm lag and inability to distinguish fault types.

[0006] The above-mentioned technical objective of the present invention is achieved through the following technical solution: Firstly, a method for monitoring and early warning of composite parameters of aspirating air sampling filter cotton is provided, including the following steps: Obtain the upstream and downstream air pressures of the filter cotton, and calculate the steady-state pressure difference based on the upstream and downstream air pressures; Acquire airflow pulsation signals and perform spectral analysis on the airflow pulsation signals to extract pulsation frequency and pulsation amplitude; Based on the changes in the steady-state pressure difference, the pulsation frequency, and the pulsation amplitude relative to their respective reference values, a fault discrimination matrix is ​​used to distinguish between normal state, fiber aging warning, dust accumulation blockage fault, and filter cotton damage fault. Based on the differentiation results, the corresponding graded early warning signal is output.

[0007] Furthermore, the airflow pulsation signal is collected by a pressure sensor or pulsation detection diaphragm encapsulated inside a pressure-stabilizing and dust-proof buffer air chamber. The inlet and outlet of the pressure-stabilizing and dust-proof buffer air chamber are both covered with polytetrafluoroethylene microporous flow equalization membranes to isolate dust and stabilize airflow.

[0008] Furthermore, the spectrum analysis includes performing a fast Fourier transform on the airflow pulsation signal, extracting the dominant frequency peak as the pulsation frequency, and extracting the amplitude corresponding to the dominant frequency peak as the pulsation amplitude.

[0009] Furthermore, the method of distinguishing between normal state, fiber aging warning, dust accumulation and blockage fault, and filter cotton damage fault through the fault discrimination matrix includes: When the change in steady-state differential pressure is less than the lower limit threshold of aging differential pressure, the pulsation frequency is less than the damage frequency offset threshold, and the change in pulsation amplitude is less than the damage amplitude threshold, it is judged to be in a normal state. When the steady-state pressure difference change is greater than or equal to the lower limit threshold of the aging pressure difference and less than or equal to the blockage pressure difference threshold, the pulsation frequency offset is greater than or equal to the aging frequency offset threshold, and the pulsation amplitude change is less than the aging amplitude threshold, it is determined to be a fiber aging warning. When the steady-state pressure difference change is greater than or equal to the blockage pressure difference threshold, and the pulsation amplitude change is less than or equal to the blockage amplitude threshold, it is determined to be a dust accumulation blockage fault. When the steady-state pressure difference change is less than the preset pressure difference value, the pulsation frequency offset is greater than or equal to the damage frequency offset threshold, and the pulsation amplitude change is greater than or equal to the damage amplitude threshold, the filter cotton is determined to be damaged.

[0010] Furthermore, the preset differential pressure value is the difference between the blockage differential pressure threshold and the aging differential pressure lower limit threshold.

[0011] Furthermore, the tiered early warning signals include a green normal indication, a yellow planned maintenance indication, and a red immediate replacement indication; A yellow indicator is output when the problem is identified as a fiber aging warning, and a red indicator is output when the problem is identified as a dust accumulation blockage or filter cotton damage.

[0012] Furthermore, the method also includes: Once the determination result of the fault discrimination matrix remains stable for a preset anti-shake duration, a corresponding graded early warning signal is output.

[0013] Furthermore, the establishment of the benchmark value specifically involves: After installing the clean filter cotton, the average steady-state pressure difference within a preset time period is collected as the steady-state pressure difference reference value. The airflow pulsation signal within a preset time period is collected and its spectrum is analyzed. The peak value of the main frequency is used as the reference value of the pulsation frequency, and the amplitude corresponding to the peak value of the main frequency is used as the reference value of the pulsation amplitude.

[0014] Furthermore, the method also includes: Based on the rate of change of the steady-state pressure difference and the threshold in the fault discrimination matrix, the remaining service life of the filter cotton is estimated, and the remaining service life is output through the graded early warning signal or communication module.

[0015] Secondly, a device for monitoring and early warning of composite parameters of aspirating air sampling filter cotton is provided, comprising: The air pressure acquisition module is used to acquire the upstream and downstream air pressures of the filter cotton, and calculate the steady-state pressure difference based on the upstream and downstream air pressures. The signal analysis module is used to acquire airflow pulsation signals and perform spectral analysis on the airflow pulsation signals to extract the pulsation frequency and pulsation amplitude. The fault discrimination module is used to distinguish normal state, fiber aging warning, dust accumulation and blockage fault and filter cotton damage fault by means of the fault discrimination matrix based on the change of steady-state pressure difference, the pulsation frequency and the pulsation amplitude relative to their respective reference values. The graded early warning module is used to output corresponding graded early warning signals based on the differentiation results.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention provides a method for monitoring and early warning of composite parameters of a suction-type air sampling filter cotton. It calculates the steady-state pressure difference by simultaneously acquiring the upstream and downstream air pressures of the filter cotton, and performs spectral analysis on the airflow pulsation signal to extract the pulsation frequency and amplitude. The changes in steady-state pressure difference, pulsation frequency, and pulsation amplitude relative to their respective reference values ​​are then input into a fault discrimination matrix for comprehensive judgment, achieving a leap from a single pressure difference dimension to three-dimensional feature fusion. The steady-state pressure difference reflects the macroscopic resistance change of the filter cotton, the pulsation frequency reflects the microscopic acoustic characteristics change of the filter cotton's pore structure, and the pulsation amplitude reflects the degree of airflow energy attenuation. These three factors characterize the state of the filter cotton from different physical dimensions. When the filter cotton undergoes fiber aging, changes in the pore microstructure first cause a shift in the pulsation frequency, while the steady-state pressure difference has not yet increased significantly. When the filter cotton suffers minor damage, airflow short-circuiting leads to a drastic anomaly in the pulsation amplitude, while the steady-state pressure difference does not decrease significantly. When the filter cotton is clogged with dust, the steady-state pressure difference rises sharply while the pulsation amplitude attenuates. The fault discrimination matrix comprehensively utilizes the changing trends and threshold relationships of these three feature quantities, enabling it to identify aging warnings and damage faults in the early stages of filter cotton failure. Compared with the traditional method that relies solely on a single steady-state pressure difference, it improves the sensitivity and specificity of fault identification, achieving early warning and accurate classification of filter cotton status.

[0017] 2. This invention achieves physical isolation between the sensing element and the high-dust sampling airflow by encapsulating the airflow pulsation signal acquisition element inside a pressure-stabilized, dust-proof, and buffered air chamber, and attaching polytetrafluoroethylene (PTFE) microporous flow-equalizing filter membranes to both the air inlet and outlet of the chamber. The PTFE microporous flow-equalizing filter membrane traps dust particles larger than 0.2μm to 2μm in the air while allowing gas molecules to pass through smoothly. This ensures that the airflow entering the chamber is filtered of dust and undergoes flow equalization, forming a stable pressure field. This structural design not only eliminates dust contamination and wear on the sensing element, allowing the sensor's measurement accuracy to remain at its factory state for a long time without the need for mid-term calibration, but also suppresses high-frequency noise interference in the airflow through flow equalization, improving the signal-to-noise ratio of the pulsation signal, thereby providing a high-quality raw signal for subsequent spectrum analysis.

[0018] 3. This invention establishes a mapping relationship between steady-state pressure difference changes, pulsation frequency shifts, pulsation amplitude changes, and four filter cotton states through eight thresholds and four discrimination rules set in the fault discrimination matrix. Specifically, the judgment condition for the normal state sets a low threshold to ensure no false alarms when the filter cotton is clean; the judgment condition for fiber aging warning utilizes the high sensitivity of pulsation frequency shifts to microstructural changes, identifying aging trends before a significant increase in pressure difference; the judgment condition for dust accumulation and blockage combines a significant increase in pressure difference with amplitude attenuation, eliminating interference from pressure difference fluctuations caused by changes in fan speed; and the judgment condition for filter cotton damage combines a sudden drop in pressure difference with drastic anomalies in frequency amplitude, reliably identifying minor damage. The preset pressure difference value is defined as the difference between the blockage pressure difference threshold and the aging pressure difference lower limit threshold, ensuring logical connection between damage and blockage judgments in the pressure difference dimension and avoiding blind spots in the judgment between the two.

[0019] 4. This invention transforms complex fault diagnosis results into intuitive visual signals by setting up three levels of early warning signals: green for normal operation, yellow for planned maintenance, and red for immediate replacement. The green indicator corresponds to a normal state, requiring no attention from maintenance personnel; the yellow indicator warns of fiber aging, prompting planned maintenance to be scheduled soon, allowing maintenance personnel to prepare spare parts in advance and avoid downtime due to spare parts shortages; the red indicator corresponds to dust accumulation or filter damage, indicating the need for immediate replacement, allowing maintenance personnel to quickly locate the fault type and bring the appropriate tools and spare parts to the site. This tiered early warning mechanism seamlessly integrates into existing periodic inspection procedures. Maintenance personnel do not need to carry professional testing tools; they can predict the fault type and urgency simply by the indicator light color, significantly reducing troubleshooting time and improving maintenance efficiency.

[0020] 5. This invention provides maintenance personnel with a quantified maintenance time reference by predicting the remaining service life of the filter cotton based on the rate of change of steady-state pressure difference and the threshold in the fault discrimination matrix. Utilizing the rate of change and acceleration of pressure difference, combined with a uniform acceleration motion model, it calculates the time required for the current pressure difference to reach the clogging pressure threshold, dynamically adapting to changes in the dust accumulation rate of the filter cotton under different operating conditions. When dust accumulation accelerates, the estimated remaining service life will shorten accordingly; when dust accumulation slows down, the estimated remaining service life will extend. This adaptive prediction method, compared to a fixed-time-cycle maintenance strategy, is more in line with actual usage, avoiding waste caused by premature replacement and preventing filter failure due to delayed replacement. Attached Figure Description

[0021] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and form part of this application, do not constitute a limitation thereof. In the drawings: Figure 1This is a flowchart from Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the device structure in Embodiment 2 of the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0023] Example 1: A method for monitoring and early warning of composite parameters of aspirating air sampling filter cotton, such as... Figure 1 As shown, it includes the following steps: S1: Obtain the upstream and downstream air pressure of the filter cotton, and calculate the steady-state pressure difference based on the upstream and downstream air pressure; S2: Acquire airflow pulsation signals and perform spectral analysis on the airflow pulsation signals to extract pulsation frequency and pulsation amplitude; S3: Based on the changes in steady-state pressure difference, pulsation frequency, and pulsation amplitude relative to their respective reference values, the fault discrimination matrix distinguishes between normal state, fiber aging warning, dust accumulation blockage fault, and filter cotton damage fault. S4: Output the corresponding graded early warning signal based on the differentiation results.

[0024] In step S1, the upstream and downstream air pressures of the filter cotton are obtained by air pressure sensors encapsulated inside the two pressure-stabilized dustproof buffer air chambers.

[0025] Specifically, the air inlet of the upstream pressure-stabilizing and dust-proof buffer air chamber is connected to the sampling tube of the suction-type air sampling system, and the air outlet of the chamber is connected to the air inlet side pipe of the external filter cotton filter box. The sampling airflow upstream of the filter cotton enters the upstream pressure-stabilizing and dust-proof buffer air chamber through the chamber inlet. After the dust is filtered and evenly distributed by the polytetrafluoroethylene microporous flow equalization filter membrane, the airflow pressure fluctuation is effectively suppressed, forming a stable pressure field. The air pressure sensor encapsulated inside the chamber senses the stable air pressure inside the chamber and outputs the air pressure upstream of the filter cotton. Meanwhile, the inlet of the downstream pressure-stabilizing and dust-proof buffer air chamber is connected to the outlet of the external filter cotton filter box via a pipeline, and the outlet of the chamber is connected to the suction pump via a pipeline. The airflow downstream of the filter cotton enters the downstream pressure-stabilizing and dust-proof buffer air chamber through the inlet, and after being filtered and homogenized by a polytetrafluoroethylene microporous flow equalization membrane, the air pressure downstream of the filter cotton is sensed and output by a pressure sensor encapsulated inside the chamber. .

[0026] The readings from two barometric pressure sensors are read synchronously according to a preset detection cycle. The detection cycle can be flexibly set according to site conditions, ranging from 30 seconds to 5 minutes, to avoid frequent data acquisition increasing the data processing burden while ensuring timely monitoring. At the end of each acquisition cycle, the upstream pressure is read. and downstream air pressure The instantaneous value is then used to calculate the steady-state pressure difference across the filter cotton using the following formula. : .

[0027] It should be noted that after the clean filter cotton is initially installed in the aspirating air sampling system, a baseline parameter establishment procedure should be performed once. In this procedure, the data acquisition and calculation steps of this method should also be performed, and the arithmetic mean of the instantaneous steady-state pressure difference values ​​over 30 consecutive minutes should be taken to obtain the steady-state pressure difference baseline value. It is stored in non-volatile memory.

[0028] In step S2, the airflow pulsation signal is collected by a pulsation detection diaphragm encapsulated inside the voltage-stabilizing and dust-proof buffer air chamber.

[0029] Specifically, the pulsation detection diaphragm is installed inside the pressure-stabilizing and dust-proof buffer air chamber. Since both the inlet and outlet of the chamber are covered with PTFE microporous flow-equalizing filter membranes, the airflow entering the chamber has already had dust filtered out and undergone flow equalization, but still retains the inherent pressure pulsation component. The pulsation detection diaphragm senses the instantaneous pressure fluctuations of the airflow within the chamber and converts them into an analog voltage signal, which is the airflow pulsation signal. The amplitude of the airflow pulsation signal is proportional to the instantaneous change in airflow pressure, and its frequency components reflect the turbulent characteristics of the airflow after passing through the filter cotton and the passing frequency of the suction pump blades, among other characteristics.

[0030] The analog airflow pulsation signal output from the pulsation detection diaphragm is converted from analog to digital. The sampling frequency of the analog-to-digital converter is no less than 100Hz to ensure that the high-frequency components in the airflow pulsation can be captured.

[0031] Spectral analysis was performed on the digitized airflow pulsation signal. The Fast Fourier Transform (FFT) algorithm was used, with a transform window length of 1024 sampling points. A Hanning window was selected to reduce spectral leakage, and the overlap rate between adjacent windows was 50%. The FFT converted the time-domain airflow pulsation signal into a frequency-domain signal, obtaining the amplitude distribution of each frequency component.

[0032] The frequency component with the largest amplitude is extracted from the spectrum. The frequency value of this component is taken as the pulsation frequency f, with the unit Hz; the amplitude corresponding to this frequency component is taken as the pulsation amplitude A, with the unit Pa. The pulsation frequency f reflects the dominant frequency characteristic of the airflow pulsation, which is usually related to the passing frequency of the intake pump blades and its harmonics; the pulsation amplitude A reflects the energy magnitude of this dominant frequency component, which is closely related to the resistance state of the airflow passing through the filter cotton.

[0033] It should be noted that after the clean filter cotton is initially installed in the aspirating air sampling system, a baseline parameter establishment procedure should be performed once. In this procedure, the data acquisition and spectrum analysis steps of this method should also be performed, and the instantaneous values ​​of the pulsation frequency over a continuous 30-minute period should be statistically averaged to obtain the baseline value of the pulsation frequency. The corresponding pulsation amplitudes are statistically averaged to obtain the baseline value of the pulsation amplitude. They are stored together in non-volatile memory.

[0034] In step S3, the steady-state pressure difference change, the pulsation frequency offset, and the pulsation amplitude change are calculated first.

[0035] steady-state pressure difference change The calculation formula is: ; in, The current steady-state pressure difference is calculated in step S1. This is the benchmark value for steady-state pressure difference.

[0036] Pulse frequency offset The calculation formula is: ; in, To extract the current pulsation frequency, This is the reference value for the pulsation frequency. This represents the pulsation frequency offset.

[0037] Pulse amplitude change The calculation formula is: ; in, The current pulsation amplitude extracted in step S2. This is the baseline value for the pulsation amplitude. This represents the change in the amplitude of the pulsation.

[0038] The three variables mentioned above are input into the fault discrimination matrix and compared with the preset threshold to distinguish the four operating conditions.

[0039] When the steady-state pressure difference changes Less than the lower limit threshold of aging pressure difference pulsation frequency Less than the breakage frequency offset threshold And the change in pulsation amplitude Less than the damage amplitude threshold When the filter cotton's pore structure is intact and airflow is smooth, no maintenance is required.

[0040] When the steady-state pressure difference changes Greater than or equal to the lower limit threshold of aging pressure difference And less than or equal to the blockage differential pressure threshold , Pulse frequency offset Greater than or equal to the aging frequency offset threshold And the change in pulsation amplitude Less than the aging amplitude threshold When the filter cotton pores expand microscopically and its elasticity decreases, the airflow pulsation spectrum characteristics shift. However, at this point, the filter cotton still has a certain filtration efficiency and has not yet reached the point where immediate replacement is necessary.

[0041] When the steady-state pressure difference changes Greater than or equal to the blockage differential pressure threshold And the change in pulsation amplitude Less than or equal to the blockage amplitude threshold When the dust accumulation is detected, it is determined to be a dust blockage fault. Dust blockage is characterized by a large amount of dust filling the pores of the filter cotton, resulting in a significant increase in airflow resistance, a sharp rise in steady-state pressure difference, and a significant decrease in the amplitude of airflow pulsation due to energy attenuation.

[0042] When the steady-state pressure difference changes Less than the preset pressure difference value , Pulse frequency offset Greater than or equal to the breakage frequency offset threshold And the change in pulsation amplitude Greater than or equal to the damage amplitude threshold When this occurs, it is determined to be a filter cotton damage fault. The damage fault manifests as holes or cracks in the filter cotton, causing a short circuit in the airflow and a sudden drop in steady-state pressure differential. Simultaneously, the turbulence generated at the damage site causes severe anomalies in the frequency and amplitude of pulsations. The preset pressure differential value... Blockage differential pressure threshold Lower threshold of aging pressure difference The difference is calculated using the following formula: .

[0043] The values ​​of the above thresholds are determined based on the power of the on-site suction pump, the total length of the pipeline, and the local atmospheric pressure. Lower limit threshold for aging pressure difference. The value range is the steady-state pressure difference reference value. 120% to 150%, clogging differential pressure threshold The value range is the steady-state pressure difference reference value. 200% to 300%, aging frequency offset threshold The value range is the pulse frequency reference value. 5% to 10% of the breakage frequency deviates from the threshold The value range is the pulse frequency reference value. 15% to 30%, aging amplitude threshold The value range is the reference value of the pulsation amplitude. 60% to 80%, blockage amplitude threshold The value range is the reference value of the pulsation amplitude. 40% to 60%, damage amplitude threshold The value range is the reference value of the pulsation amplitude. 30% to 50%.

[0044] Before outputting the graded warning signal, anti-shake logic must be executed. The corresponding graded warning signal is output only after the fault discrimination matrix's judgment result has remained stable for a preset anti-shake duration. The preset anti-shake duration ranges from 3 to 5 minutes and is used to prevent misjudgments caused by instantaneous airflow disturbances. If the judgment result changes within the preset anti-shake duration, the timer is reset and restarted until the judgment result remains stable for the preset anti-shake duration.

[0045] It should be noted that the establishment of the benchmark value is as follows: after installing the clean filter cotton, the average steady-state pressure difference over a preset period is collected as the steady-state pressure difference benchmark value. Collect airflow pulsation signals within a preset time period and perform spectrum analysis, using the peak value of the dominant frequency as the reference value for the pulsation frequency. The amplitude corresponding to the peak value of the main frequency is used as the reference value of the pulsation amplitude. The preset time period ranges from 30 to 60 minutes to ensure that the baseline value reflects the initial state of the filter cotton.

[0046] In step S4, the graded warning signals include a green normal indication, a yellow planned maintenance indication, and a red immediate replacement indication. The green normal indication corresponds to a normal state, indicating that the filter cotton is in good condition and requires no maintenance. The yellow planned maintenance indication corresponds to a fiber aging warning, indicating that the filter cotton has shown signs of fiber aging and that planned maintenance should be scheduled in the near future. The red immediate replacement indication corresponds to dust accumulation clogging or filter cotton damage, indicating that the filter cotton has failed and needs to be replaced immediately.

[0047] Furthermore, this invention includes the estimation of the remaining service life of the filter cotton. The remaining service life of the filter cotton is estimated based on the rate of change of steady-state pressure difference and a threshold in the fault discrimination matrix. The rate of change of steady-state pressure difference... The calculation formula is: ; in, for steady-state pressure difference at time t, for steady-state pressure difference at time t, The adjustment period is set to a value ranging from 2 hours to 12 hours.

[0048] Further calculation of the acceleration due to pressure difference change The calculation formula is as follows: ; in, for The rate of change of steady-state pressure difference at time t. for The rate of change of steady-state pressure difference at time t.

[0049] Based on the acceleration of pressure difference change and the current steady-state pressure difference and the blockage differential pressure threshold The estimated remaining useful life is calculated using the following formula. : ; This invention is based on a uniformly accelerated motion model, assuming that the acceleration of pressure difference changes is constant, and calculates the time required for the current pressure difference to reach the blockage pressure difference threshold.

[0050] The estimated remaining service life is output via tiered warning signals or a communication module. Tiered warning signals indicate the remaining service life through different flashing frequencies of a yellow indicator light; for example, low-frequency flashing indicates a longer remaining time, while high-frequency flashing indicates a shorter remaining time. The communication module can send the estimated remaining service life as a data packet to the central control system or the terminal equipment of maintenance personnel for reference in scheduling maintenance.

[0051] It should be noted that the remaining service life is only calculated when the total runtime is greater than or equal to 2T, to ensure sufficient historical data for calculating the rate of change of pressure difference and acceleration, thereby improving the accuracy of the prediction. When the filter cotton is replaced, the baseline parameter establishment process is re-executed, and the remaining service life prediction is also reset accordingly.

[0052] Example 2: A device for monitoring and early warning of composite parameters of aspirating air sampling filter cotton, which is used to implement the method for monitoring and early warning of composite parameters of aspirating air sampling filter cotton described in Example 1, such as... Figure 2 As shown, it includes an external filter cotton filter box, a pressure-stabilizing and dustproof buffer air chamber, an air pressure acquisition module, a signal analysis module, a fault diagnosis module, and a graded early warning module.

[0053] An external filter cartridge is installed in the sampling pipeline of an air intake sampling system. The external filter cartridge has an air inlet and an air outlet, and contains removable filter cotton. Air enters the external filter cartridge through the air inlet, is filtered by the filter cotton, and then flows out through the air outlet. Pressure-stabilizing and dust-proof buffer chambers are arranged on both the air inlet and outlet sides of the external filter cartridge.

[0054] The pressure-stabilizing and dust-proof buffer air chamber is a one-piece injection-molded sealed cavity. It has an air inlet and an air outlet, located at opposite ends of the chamber. At both the air inlet and outlet, a polytetrafluoroethylene (PTFE) microporous flow equalization membrane is attached, with a pore size ranging from 0.2 μm to 2 μm. The PTFE microporous flow equalization membrane traps dust particles larger than the membrane pores while allowing gas molecules to pass through smoothly, thus filtering and equalizing the airflow entering the chamber. Inside the chamber, a pressure sensor (for pressure acquisition) and a pulsation detection diaphragm (for signal analysis) are encapsulated. Neither the pressure sensor nor the pulsation detection diaphragm directly contacts external dust; instead, pressure and pulsation are indirectly transmitted through the PTFE microporous flow equalization membrane and the sampling air path.

[0055] Specifically, the air pressure acquisition module is used to acquire the upstream and downstream air pressures of the filter cotton and calculate the steady-state pressure difference based on the upstream and downstream air pressures; the signal analysis module is used to acquire airflow pulsation signals and perform spectral analysis on the airflow pulsation signals to extract the pulsation frequency and pulsation amplitude; the fault discrimination module is used to distinguish between normal state, fiber aging warning, dust accumulation blockage fault, and filter cotton damage fault based on the changes in steady-state pressure difference, pulsation frequency, and pulsation amplitude relative to their respective reference values ​​through a fault discrimination matrix; and the graded warning module is used to output corresponding graded warning signals based on the discrimination results.

[0056] Working Principle: This invention calculates the steady-state pressure difference by simultaneously acquiring the upstream and downstream air pressures of the filter cotton, and performs spectral analysis on the airflow pulsation signal to extract the pulsation frequency and amplitude. The changes in steady-state pressure difference, pulsation frequency, and pulsation amplitude relative to their respective reference values ​​are then input into a fault discrimination matrix for comprehensive judgment, achieving a leap from a single pressure difference dimension to three-dimensional feature fusion. The steady-state pressure difference reflects the macroscopic resistance change of the filter cotton, the pulsation frequency reflects the microscopic acoustic characteristics change of the filter cotton's pore structure, and the pulsation amplitude reflects the degree of airflow energy attenuation. These three factors characterize the state of the filter cotton from different physical dimensions. When the filter cotton undergoes fiber aging, changes in the pore microstructure first cause a shift in the pulsation frequency, while the steady-state pressure difference has not yet increased significantly. When the filter cotton suffers minor damage, airflow short-circuiting leads to a drastic anomaly in the pulsation amplitude, while the steady-state pressure difference does not decrease significantly. When the filter cotton is clogged with dust, the steady-state pressure difference rises sharply while the pulsation amplitude attenuates. The fault discrimination matrix comprehensively utilizes the changing trends and threshold relationships of these three feature quantities, enabling it to identify aging warnings and damage faults in the early stages of filter cotton failure. Compared with the traditional method that relies solely on a single steady-state pressure difference, it improves the sensitivity and specificity of fault identification, achieving early warning and accurate classification of filter cotton status.

[0057] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0058] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0059] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0060] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0061] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for monitoring and early warning of composite parameters of aspirating air sampling filter cotton, characterized in that, Includes the following steps: Obtain the upstream and downstream air pressures of the filter cotton, and calculate the steady-state pressure difference based on the upstream and downstream air pressures; Acquire airflow pulsation signals and perform spectral analysis on the airflow pulsation signals to extract pulsation frequency and pulsation amplitude; Based on the changes in the steady-state pressure difference, the pulsation frequency, and the pulsation amplitude relative to their respective reference values, a fault discrimination matrix is ​​used to distinguish between normal state, fiber aging warning, dust accumulation blockage fault, and filter cotton damage fault. Based on the differentiation results, the corresponding graded early warning signal is output.

2. The method for monitoring and early warning of composite parameters of aspirating air sampling filter cotton according to claim 1, characterized in that, The airflow pulsation signal is collected by a pressure sensor or a pulsation detection diaphragm encapsulated inside a pressure-stabilized, dust-proof, and buffer air chamber. The inlet and outlet of the pressure-stabilizing and dust-proof buffer air chamber are both covered with polytetrafluoroethylene microporous flow equalization membranes to isolate dust and stabilize airflow.

3. The method for monitoring and early warning of composite parameters of aspirating air sampling filter cotton according to claim 1, characterized in that, The spectrum analysis includes performing a fast Fourier transform on the airflow pulsation signal, extracting the dominant frequency peak as the pulsation frequency, and extracting the amplitude corresponding to the dominant frequency peak as the pulsation amplitude.

4. The method for monitoring and early warning of composite parameters of aspirating air sampling filter cotton according to claim 1, characterized in that, The method of distinguishing between normal state, fiber aging warning, dust accumulation and blockage, and filter cotton damage through a fault discrimination matrix includes: When the change in steady-state differential pressure is less than the lower limit threshold of aging differential pressure, the pulsation frequency is less than the damage frequency offset threshold, and the change in pulsation amplitude is less than the damage amplitude threshold, it is judged to be in a normal state. When the steady-state pressure difference change is greater than or equal to the lower limit threshold of the aging pressure difference and less than or equal to the blockage pressure difference threshold, the pulsation frequency offset is greater than or equal to the aging frequency offset threshold, and the pulsation amplitude change is less than the aging amplitude threshold, it is determined to be a fiber aging warning. When the steady-state pressure difference change is greater than or equal to the blockage pressure difference threshold, and the pulsation amplitude change is less than or equal to the blockage amplitude threshold, it is determined to be a dust accumulation blockage fault. When the steady-state pressure difference change is less than the preset pressure difference value, the pulsation frequency offset is greater than or equal to the damage frequency offset threshold, and the pulsation amplitude change is greater than or equal to the damage amplitude threshold, the filter cotton is determined to be damaged.

5. The method for monitoring and early warning of composite parameters of aspirating air sampling filter cotton according to claim 4, characterized in that, The preset differential pressure value is the difference between the blockage differential pressure threshold and the aging differential pressure lower limit threshold.

6. The method for monitoring and early warning of composite parameters of aspirating air sampling filter cotton according to claim 4, characterized in that, The graded early warning signals include a green normal indication, a yellow planned maintenance indication, and a red immediate replacement indication; A yellow indicator is output when the problem is identified as a fiber aging warning, and a red indicator is output when the problem is identified as a dust accumulation or filter cotton damage.

7. The method for monitoring and early warning of composite parameters of aspirating air sampling filter cotton according to claim 4, characterized in that, The method also includes: Once the determination result of the fault discrimination matrix remains stable for a preset anti-shake duration, a corresponding graded early warning signal is output.

8. The method for monitoring and early warning of composite parameters of aspirating air sampling filter cotton according to claim 1, characterized in that, The establishment of the benchmark value is specifically as follows: After installing the clean filter cotton, the average steady-state pressure difference within a preset time period is collected as the steady-state pressure difference benchmark value. The airflow pulsation signal within a preset time period is collected and its spectrum is analyzed. The peak value of the main frequency is used as the reference value of the pulsation frequency, and the amplitude corresponding to the peak value of the main frequency is used as the reference value of the pulsation amplitude.

9. The method for monitoring and early warning of composite parameters of aspirating air sampling filter cotton according to claim 1, characterized in that, The method also includes: Based on the rate of change of the steady-state pressure difference and the threshold in the fault discrimination matrix, the remaining service life of the filter cotton is estimated, and the remaining service life is output through the graded early warning signal or communication module.

10. A suction-type air sampling filter cotton composite parameter monitoring and early warning device, characterized in that, include: The air pressure acquisition module is used to acquire the upstream and downstream air pressures of the filter cotton, and calculate the steady-state pressure difference based on the upstream and downstream air pressures. The signal analysis module is used to acquire airflow pulsation signals and perform spectral analysis on the airflow pulsation signals to extract the pulsation frequency and pulsation amplitude. The fault discrimination module is used to distinguish normal state, fiber aging warning, dust accumulation and blockage fault and filter cotton damage fault by means of the fault discrimination matrix based on the change of steady-state pressure difference, the pulsation frequency and the pulsation amplitude relative to their respective reference values. The graded early warning module is used to output corresponding graded early warning signals based on the differentiation results.

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