A real-time detection system and method for aerosol mass concentration based on TEOM

Abstract

The present invention belongs to the field of aerosol detection safety evaluation, and specifically relates to a real-time detection system and method for aerosol mass concentration based on TEOM, including: a control and analysis module, a gas flow control module connected thereto, an air control module, and a TEOM oscillation detection module; the gas flow control module is used to keep the gas output flow rate constant; the air control module is used to transport the sample gas to be measured mixed with aerosol or air to the TEOM oscillation detection module; the control and analysis module is used to obtain the output flow rate of the gas flow control module and send a control signal to the gas flow control module; at the same time, according to the oscillation frequencies of different filter holders, the mass concentration of aerosol particles per unit time is obtained in real time. The present invention can continuously measure and approximately calculate the total particle mass concentration of aerosol per unit volume in real time, which is particularly important for units such as the field of aerosol inhalation safety evaluation that require a large amount of dense data.

Description

Technical Field

[0001] The present invention belongs to the field of aerosol detection safety evaluation, and specifically relates to a real-time detection system and method for aerosol mass concentration based on TEOM. Background Art

[0002] An air aerosol particle mass concentration detection device is a necessary device for monitoring the atmospheric environmental pollution degree and detecting the aerosol concentration in inhalation safety evaluation. With the country's attention and emphasis on atmospheric environmental pollution and the in-depth research in the field of inhalation aerosol inhalation safety, there is an urgent need for a device that can simply and conveniently, real-time detect and truly and accurately present the aerosol mass concentration in the gas. However, due to the very complex composition of aerosol particles, the densities, refractive indices, volatilities, and air movement states of various different components are all different, and the current detection instruments on the market are all based on the light refraction method (represented by CEL-712 and HRH-AOCM, which are only sensitive to the volume of particulate matter but cannot accurately distinguish particulate matter with different densities), and chemical analysis methods (usually high-performance liquid chromatography, which is time-consuming and laborious and requires a long time to obtain data), and the total mass concentration of aerosols cannot be presented in real time and effectively. Summary of the Invention

[0003] The purpose of the present invention is to provide a real-time detection system and method for aerosol mass concentration based on TEOM, which can comprehensively consider the air flow rate data and temperature and humidity correction coefficients to accurately present the total mass concentration of aerosols in the current air in real time, so as to overcome the defect that the total mass concentration of aerosols cannot be presented in real time and effectively.

[0004] The technical solution adopted by the present invention to achieve the above purpose is: a real-time detection system for aerosol mass concentration based on TEOM, including: a control and analysis module, and a gas flow control module, an air comparison module, and a TEOM oscillation detection module connected thereto;

[0005] The gas flow control module is used to receive the control signal sent by the control and analysis module to keep the gas output flow rate constant;

[0006] The air comparison module is used to open the path of the sample to be tested or the air path according to the control instruction sent by the control and analysis module, and transport the aerosol sample gas to be tested or air mixed with it to the TEOM oscillation detection module;

[0007] The TEOM oscillation detection module is used to detect the oscillation frequencies of different filter membrane clips when receiving the aerosol sample gas to be tested or air mixed with it and the control signal sent by the control and analysis module, and send them to the control and analysis module in real time;

[0008] The control and analysis module is used to obtain the output flow rate of the gas flow control module according to the current seasonal average temperature and average air pressure, and send a control signal to the gas flow control module; meanwhile, it obtains the oscillation frequencies of different filter membrane clips detected by the TEOM oscillation detection module, and obtains the mass concentration of aerosol particles per unit time in real time.

[0009] The air control module includes a device housing, an air delivery pipeline and a pipeline for the sample to be measured connected to the device housing;

[0010] There are two air inlets and one air outlet on the device housing; one air inlet is connected to the air delivery pipeline, the other air inlet is connected to the pipeline for the sample to be measured, and the air outlet is connected to the TEOM oscillation detection module through a pipeline;

[0011] Solenoid valve A and solenoid valve B are respectively provided on the air delivery pipeline and the pipeline for the sample to be measured, and solenoid valve A and solenoid valve B are respectively connected to the control and analysis module;

[0012] An air filter is also provided on the air delivery pipeline.

[0013] The TEOM oscillation detection module includes: an oscillation detection tube, a laser Doppler vibrometer, a filter membrane clip, a through electromagnetic coil and an AC power supply;

[0014] The oscillation detection tube is arranged perpendicular to the ground. One end of the oscillation detection tube is an oscillation end, which is connected to the air outlet of the air control module, and the other end is an air outlet end, which is connected to the gas flow control module;

[0015] There are two through electromagnetic coils, which are symmetrically arranged outside the oscillation end of the oscillation detection tube through fixed brackets and are respectively connected to the AC power supply;

[0016] A filter slot is arranged inside the oscillation end of the oscillation detection tube, and the filter membrane clip is installed in the filter slot to realize the replacement of filter membrane clips with different masses during the detection process;

[0017] The laser Doppler vibrometer is connected to the control and analysis module, and the emission direction of the laser detection end of the laser Doppler vibrometer is arranged corresponding to the outer wall of the oscillation end of the oscillation detection tube.

[0018] The oscillation detection tube is of a conical structure, and the inner wall of the oscillation end is coated with a nano-hollow glass microsphere coating.

[0019] The gas flow control module includes: a suction pump, a gas flow controller and an air filter connected in sequence;

[0020] A flowmeter and a solenoid valve are provided on the pipeline between the gas flow controller and the air filter; the input end of the air filter is connected to the air outlet end of the TEOM oscillation detection module;

[0021] Both the air extraction pump and the gas flow controller are connected to the control and analysis module. When the control and analysis module sends a control signal, after the air extraction pump receives the air extraction pump control signal, the air extraction pump starts and provides the air extraction power; the gas flow controller receives the gas flow controller control signal, and the gas flow controller adjusts the opening and closing degree of the solenoid valve to make the value of the flowmeter equal to the value set by the control and analysis module, so as to control the gas flow rate.

[0022] A control method for a real-time detection system of aerosol mass concentration based on TEOM includes the following steps:

[0023] 1) The gas flow controller receives the control signal sent by the control and analysis module to keep the gas output flow rate constant;

[0024] 2) Obtain the elastic coefficient of the oscillation detection tube in the TEOM oscillation detection module;

[0025] 3) Detect the oscillation frequency of the air through a laser Doppler vibrometer and send the detected oscillation frequency of the air to the control and analysis module;

[0026] The laser Doppler vibrometer of the TEOM oscillation detection module detects the oscillation frequency of the sample gas to be measured and sends the detected oscillation frequency of the sample gas to be measured to the control and analysis module;

[0027] 4) Replace N groups of filter membrane clips with different masses. Each time a filter membrane clip is replaced, execute step 3), and after sending all the detected oscillation frequency data to the control and analysis module, execute step 5);

[0028] 5) The control and analysis module analyzes according to all the oscillation frequency data to obtain the aerosol particle mass concentration in the sample gas to be measured.

[0029] The specific content of step 1) is as follows:

[0030] The control and analysis module obtains the output flow rate of the gas flow control module according to the current seasonal average temperature and average air pressure set by the user. Specifically:

[0031] The control and analysis module controls the output flow rate of the gas flow control module to be:

[0032]

[0033] Among them, FlowSP1 is the target volume flow of the gas flow controller, TempAVG is the average temperature set by the user, TempSTD is the standard temperature, PAVG is the seasonal average air pressure input by the user, and PSTD is the standard pressure;

[0034] Compare the measured value of the flowmeter on the current gas flow controller with the output flow rate FlowSP0, and adjust the opening and closing degree of the solenoid valve on the gas flow control module to keep the output flow rate of the gas flow controller constant at FlowSP0.

[0035] The specific content of step 2) is as follows:

[0036] Measure the vibration frequency of the pre-weighed test gas passing through the filter membrane clip as the final frequency F1, and use a laser Doppler vibrometer to detect the oscillation frequency of the air passing through the filter membrane clip as the initial frequency F0;

[0037] Then the elastic coefficient of the oscillation detection tube is:

[0038]

[0039] Among them, dm is the mass of the test sample gas passing through the filter membrane clip - the mass of the filter membrane clip passing through the air.

[0040] The specific content of step 3) is as follows:

[0041] Introduce air as a control group. The control analysis module controls the solenoid valve B to close and the solenoid valve A to open. Then the air flows out along one of the air inlets through the air filter and enters the TEOM oscillation detection module; the air passes through the filter membrane clip of the TEOM oscillation detection module. The control analysis module controls the coil to be energized, and the laser Doppler vibrometer detects the oscillation frequency of the air and sends the detected oscillation frequency of the air to the control analysis module;

[0042] After the laser Doppler vibrometer detects the oscillation frequency of the air, the control analysis module controls the solenoid valve A to close and the solenoid valve B to open. Then the sample gas to be measured flows out at the other air inlet along the gas flow direction and enters the TEOM oscillation detection module; the sample gas to be measured passes through the filter membrane clip of the TEOM oscillation detection module. The control analysis module controls the coil to be energized, and the laser Doppler vibrometer detects the oscillation frequency of the sample gas to be measured and sends the detected oscillation frequency of the sample gas to be measured to the control analysis module.

[0043] The specific content of step 5) is as follows:

[0044] The control analysis module respectively obtains N groups of oscillation frequency data under different mass filter membrane clips collected by the Doppler laser vibrometer as F1 - FN;

[0045] According to Obtain the mass change amounts corresponding to N groups of different quality filter membrane clips respectively, that is: dm1 - dmN;

[0046] Fit dm1 - dmN to obtain the power trend curve of the mass change amount, that is:

[0047]

[0048] Substitute dm1 - dmN into M0, and calculate K2 and n according to the measured FN and F0 each time;

[0049] Substitute the obtained K2 and n into the following formula, then the aerosol particle mass concentration in the sample gas to be measured:

[0050]

[0051] Among them, T is the air flow sampling duration controlled by the control analysis module, K2 is the fitting calculation coefficient of each filter membrane clip, n is the fitting calculation power of each filter membrane clip, K0 is the elastic coefficient of the oscillation detection tube without load; F0 is the oscillation frequency of air passing through the filter membrane clip, F1 is the vibration frequency of the sample gas to be measured passing through the filter membrane clip, FlowSP1 is the volume flow rate of the set point, TempAVG is the average temperature set by the user, TempSTD is the standard temperature, PAVG is the average seasonal air pressure set by the user, and PSTD is the standard pressure.

[0052] The present invention has the following beneficial effects and advantages:

[0053] 1. The present invention is similar to the traditional standard balance weighing method in operation and can be self-inspected and verified, but it also makes up for many shortcomings of the traditional balance weighing method, and is convenient for large-scale promotion and alternative use compared with other complex equipment.

[0054] 2. The present invention is uniformly controlled and processed by the control analysis module, and the software can automatically tune and fit the calculation, greatly reducing the manual participation of personnel and avoiding calculation errors.

[0055] 3. The present invention fills the blank in the domestic market that there is no device that can accurately measure the total particle mass concentration of aerosols in real time;

[0056] 4. The present invention can continuously measure (the value can be obtained in 10s), and approximately calculate the total particle mass concentration per unit volume of aerosols in real time, which is particularly important for units with a large amount and density of data requirements in the field of aerosol inhalation safety evaluation. Brief Description of the Drawings

[0057] Figure 1 Structural schematic diagram of the present invention;

[0058] Figure 2 Principle schematic diagram of the gas flow control module of the present invention;

[0059] Figure 3 Schematic diagram of the principle of the air control module of the present invention;

[0060] Figure 4 Schematic diagram of the principle of the TEOM oscillation detection module of the present invention;

[0061] Figure 5 Power-law trend curve of the mass change of the present invention. Specific implementation mode

[0062] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0063] As Figure 1 shown, the TEOM aerosol mass concentration detection system mainly consists of four parts, namely a control and analysis module and a gas flow control module, an air control module, and a TEOM oscillation detection module connected thereto;

[0064] The gas flow control module is used to receive the control signal sent by the control and analysis module to keep the output gas flow rate constant;

[0065] The air control module is used to open the path of the sample to be tested or the air path according to the control instruction sent by the control and analysis module, and transport the aerosol sample gas or air mixed with the sample to be tested to the TEOM oscillation detection module;

[0066] The TEOM oscillation detection module is used to detect the oscillation frequencies of different filter membrane clips when receiving the aerosol sample gas or air mixed with the sample to be tested and the control signal sent by the control and analysis module, and send them to the control and analysis module in real time;

[0067] The control and analysis module is used to obtain the output flow rate of the gas flow control module according to the average temperature and average air pressure of the current season, and send a control signal to the gas flow control module; at the same time, according to the oscillation frequencies of different filter membrane clips detected by the TEOM oscillation detection module, it obtains the mass concentration of aerosol particles per unit time in real time.

[0068] As Figure 2As shown in the figure, it is a schematic diagram of the principle of the gas flow control module of the present invention. The first part is the constant air flow rate control module. This module consists of a 21-type gas flow controller of the ALICAT brand (range: 0.1 - 10.0 L / min, including two components: a flow meter and a solenoid valve, installed on the pipeline between the gas flow controller and the air filter), an air filter (SMC brand, filtration accuracy ≤ 0.01 um), and an air extraction pump (a conventional oil-free vacuum pump powered by 220V, maximum vacuum negative pressure ≤ -90 Kpa); the air extraction pump, the gas flow controller, and the air filter are connected in sequence, and the input end of the air filter is connected to the outlet end of the TEOM oscillation detection module; both the air extraction pump and the gas flow controller are connected to the control and analysis module;

[0069] According to the control signals of the control and analysis module (including the operation signal of the air extraction pump and the gas flow control signal), first, the control and analysis module system sends a control signal. The vacuum pump receives the signal and starts to operate to provide the air extraction power. The gas flow controller receives the signal and adjusts the opening and closing degree of the solenoid valve according to the measured signal of the flow meter (the gas flow controller has its own PID closed-loop control and can self-tune to reach the set flow rate). The filter filters the particulate impurities in the extracted gas to ensure that the flow controller and the air extraction pump are not contaminated. In this way, this module can extract a constant-speed and stable air flow D from the connected environment, and the flow rate control accuracy ≤ 0.1 L / min.

[0070] As Figure 3 shown in the figure, it is a schematic diagram of the principle of the air comparison module of the present invention. The second part is the air comparison module, which includes: a device housing, an air delivery pipeline and a pipeline for the sample to be measured connected to the device housing;

[0071] There are two air inlets and one air outlet on the device housing; one air inlet is connected to the air delivery pipeline, the other air inlet is connected to the pipeline for the sample to be measured, and the air outlet is connected to the TEOM oscillation detection module through a pipeline;

[0072] Solenoid valves A and B are respectively installed on the air delivery pipeline and the pipeline for the sample to be measured, and solenoid valves A and B are respectively connected to the control and analysis module;

[0073] An air filter is also installed on the air delivery pipeline.

[0074] As Figure 4 shown in the figure, it is a schematic diagram of the principle of the TEOM oscillation detection module of the present invention. The third part is the TEOM oscillation detection module:

[0075] The TEOM oscillation detection module includes: an oscillation detection tube, a laser Doppler vibrometer, a filter membrane clip, a solenoid coil, and an AC power supply;

[0076] The oscillation detection tube is arranged perpendicular to the ground. One end of the oscillation detection tube is the oscillation end, which is connected to the air outlet of the air comparison module, and the other end is the air outlet end, which is connected to the gas flow control module;

[0077] There are two electromagnetic coils, which are symmetrically arranged outside the oscillation end of the oscillation detection tube through fixed brackets and are respectively connected to an AC power supply;

[0078] A filter film slot is provided inside the oscillation end of the oscillation detection tube, and the filter film clip is installed in the filter film slot to realize the replacement of filter film clips with different masses during the detection process;

[0079] The laser Doppler vibrometer is connected to the control and analysis module, and the emission direction of the laser detection end of the laser Doppler vibrometer is set corresponding to the outer wall of the oscillation end of the oscillation detection tube.

[0080] The inner wall of the oscillation end of the oscillation detection tube is coated with a nano-hollow glass microsphere coating. For the nano-hollow glass microsphere coating, it only needs to contain glass microspheres and other adhesives. The particle size of the glass microspheres is ≤1um. This material is often used as a surface thermal insulation material after being mixed with other adhesives due to its good reflection effect on light.

[0081] TEOM (Tapered Element Oscillating Microbalance) is that in the mass sensor, the oscillation detection tube is an oscillating hollow conical tube, and a replaceable filter film clip is installed at its oscillation end. The oscillation frequency depends on the characteristics of the conical tube and its mass. The laser Doppler vibrometer is used to detect the vibration frequency of the conical tube. When in use, an AC voltage with a frequency of 24V and 50HZ is applied to the coils on both sides of the conical tube to make the conical tube vibrate left and right at a fixed frequency. This is the blank group; then the sampling air flow is connected to pass through the filter film, and the particulate matter in the air flow is deposited on the filter film. The change in the mass of the filter film causes a change in the oscillation frequency. The mass of the particulate matter deposited on the filter film is calculated through the change in the oscillation frequency, and then the mass concentration of the particulate matter in this period is calculated based on the flow rate, the on-site ambient temperature and air pressure.

[0082] The principle of TEOM is to compare the oscillation of the conical element at its natural frequency (air oscillation frequency) with the oscillation frequency under the condition of a particulate-laden mass (oscillation frequency of the aerosol particle-enriched oscillation). (The oscillation frequency of the oscillation detection tube is determined by the physical characteristics of the oscillation device, the mass of the filter membrane participating in the oscillation, and the mass of the particulate matter deposited on the filter membrane. Due to the physical characteristics of the TEOM oscillation device, the mass of the filter membrane participating in the oscillation is fixed and unchanged. Therefore, the oscillation frequency of the oscillation device actually depends on the mass of the particulate matter on the filter membrane.) The oscillation frequency is measured by a laser Doppler vibrometer (to ensure the sensitivity of the vibrometer, fixed scattering microbeads can be coated on the outer layer of the conical element). When the air flow containing aerosol particles enters the TEOM conical tube, the aerosol is filtered and attached to the filter membrane, and the air is pumped away by the air flow constant speed control module. At this time, the oscillation coil is energized, and the system frequency value can be measured by the Doppler vibrometer and transmitted to the backend control analysis module control and calculation module in real time.

[0083] As Figure 1 shown, the detection method of the present invention is specifically as follows:

[0084] 1) The gas flow controller receives the control signal sent by the control analysis module to keep the gas output flow rate constant;

[0085] 2) Obtain the elastic coefficient of the oscillation detection tube in the TEOM oscillation detection module;

[0086] 3) Detect the oscillation frequency of the air through a laser Doppler vibrometer and send the detected oscillation frequency of the air to the control analysis module;

[0087] The laser Doppler vibrometer of the TEOM oscillation detection module detects the oscillation frequency of the sample gas to be measured and sends the detected oscillation frequency of the sample gas to be measured to the control analysis module;

[0088] 4) Replace 5 groups of filter membrane clips with different masses. Each time a filter membrane clip is replaced, execute step 3), and after sending all the detected oscillation frequency data to the control analysis module, execute step 5);

[0089] 5) The control analysis module analyzes according to all the oscillation frequency data to obtain the aerosol particle mass concentration in the sample gas to be measured.

[0090] For step 1), in this embodiment, obtaining the output flow rate of the gas flow control module is specifically as follows:

[0091] The control analysis module is based on the current seasonal average temperature and average air pressure set by the user. For the flow rate calculation, under standard temperature and pressure of 25°C and 1 standard atmosphere, the user must input the seasonal average temperature (Ave.Temp.) and average atmospheric pressure (Ave.Pres.) of the monitoring point, so that the instrument samples at the corrected volumetric flow rate. The processor calculates the correct mass flow rate set point (flow rate) through the following formula:

[0092] The control analysis module controls the output flow rate of the gas flow control module to be:

[0093]

[0094] where FlowSP1 is the target volumetric flow rate of the gas flow controller (equivalent to the flow rate at 25°C and 1 atmosphere), TempAVG is the average temperature set by the user, TempSTD is the standard temperature (25°C), PAVG is the seasonal average air pressure (atmospheric pressure, 1 atmosphere is 1013.2 mbar or 760 mmHg) input by the user, and PSTD is the standard pressure (1 Atm);

[0095] According to the comparison between the measured value of the flow meter on the current gas flow controller and the output flow rate FlowSP0, adjust the opening and closing degree of the solenoid valve on the gas flow control module to make the gas flow controller maintain a constant output flow rate to FlowSP0.

[0096] Step 2), specifically:

[0097] Measure the vibration frequency of the pre-weighed test gas passing through the filter membrane clip as the final frequency F1, and the laser Doppler vibrometer detects the oscillation frequency of the air passing through the filter membrane clip as the initial frequency F0;

[0098] The conical element is essentially a hollow cantilever with a specific elastic coefficient and mass. In any elastic-mass system, if the mass increases, the oscillation frequency decreases and follows the following formula:

[0099] F = (K / M)^0.5

[0100] where: F = frequency; K = elastic coefficient; M = mass

[0101] K and M have the same unit, and the changes in mass and frequency can be expressed as:

[0102] Then the elastic coefficient of the oscillation detection tube is:

[0103]

[0104] Wherein, dm is the mass of the test sample gas passing through the filter membrane clip - the mass of the filter membrane clip of the passing air. Therefore, K0 (as the calibration constant of the instrument) is determined by measuring the frequencies with or without a specific mass (pre - weighed TEOM filter membrane assembly).

[0105] Step 3) is specifically as follows:

[0106] Air is introduced as the control group. The control analysis module controls the solenoid valve B to close and the solenoid valve A to open. Then the air flows out along one of the air inlets through the air filter and enters the TEOM oscillation detection module; the air passes through the filter membrane clip of the TEOM oscillation detection module. The control analysis module controls the coil to be energized, and the laser Doppler vibrometer detects the oscillation frequency of the air and sends the detected oscillation frequency of the air to the control analysis module;

[0107] After the laser Doppler vibrometer detects the oscillation frequency of the air, the control analysis module controls the solenoid valve A to close and the solenoid valve B to open. Then the sample gas to be measured flows out at the other air inlet along the air flow direction and enters the TEOM oscillation detection module; the sample gas to be measured passes through the filter membrane clip of the TEOM oscillation detection module. The control analysis module controls the coil to be energized, and the laser Doppler vibrometer detects the oscillation frequency of the sample gas to be measured and sends the detected oscillation frequency of the sample gas to be measured to the control analysis module.

[0108] In step 5), this embodiment uses 5 filter membrane clips with different weights. The specific method is as follows:

[0109] The control analysis module is based on 5 groups of filter membrane clips with different weights (respectively M1, M2, M3, M4, M5) collected by the Doppler laser vibrometer. Then the oscillation coil is energized, and the Doppler laser vibrometer will respectively give the oscillation frequency data under different masses (respectively F1, F2, F3, F4, F5). The data of this embodiment is specifically: M1 = 2g, M2 = 4g, M3 = 8g, M4 = 16g, M5 = 32g; F1 = 500Hz, F2 = 230Hz, F3 = 130Hz, F4 = 90Hz, F5 = 35Hz;

[0110] For the above F1 - F5 through the formula The mass change amounts corresponding to 5 groups of filter membrane clips with different masses are respectively obtained, that is: dm1 - dm5;

[0111] Fit dm1 - dm5 to obtain the power - law trend curve of the mass change amount, as Figure 5 shown, that is, the power - law trend curve graph of the mass change amount of the present invention. The curve is:

[0112]

[0113] Substitute dm1 - dmN into M0, and calculate K2 and n according to the measured FN and F0 each time. In this embodiment, K2 = 1681.3 and n = -1.088 are obtained.

[0114] Substitute the obtained K2 = 1681.3 and n = -1.088 into the following formula, then the mass concentration of aerosol particles in the sample gas to be measured:

[0115]

[0116] Where T is the air flow sampling duration controlled by the control analysis module, K2 is the fitting calculation coefficient of each filter membrane clip, n is the fitting calculation power of each filter membrane clip, K0 is the elastic coefficient of the oscillation detection tube without load; F0 is the oscillation frequency of air passing through the filter membrane clip, F1 is the vibration frequency of the sample gas to be measured passing through the filter membrane clip, FlowSP1 is the volume flow rate of the set point, TempAVG is the average temperature set by the user, TempSTD is the standard temperature, PAVG is the seasonal average air pressure set by the user, and PSTD is the standard pressure.

[0117] The present invention is based on the improved microbalance oscillation principle (TEOM) with a fixed filter membrane clip, and the control analysis module is assisted to correct the fitting algorithm. Through the constant flow suction of air, the air passes through the filter membrane at a constant speed, and the attached particulate matter will impact and settle on the membrane to change the mass of the membrane. Then, through the oscillation of the TTEOM conical element at its natural frequency and the comparison with the oscillation frequency under the condition of being loaded with particulate matter, the mass data signal of the accumulated particulate matter will be reflected in real time. Then, according to the pre-fitted software algorithm, integrating the air flow velocity data and the temperature and humidity correction coefficient, the total mass concentration of aerosol in the current air can be presented accurately in real time, making up for many deficiencies of other types of detection instruments on the current market.

[0118] The above is only the embodiment of the present invention and is not used to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, expansion, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A real-time detection system for aerosol mass concentration based on TEOM, characterized in that, Comprising: A control analysis module and a gas flow control module, an air control module, and a TEOM oscillation detection module connected thereto; The gas flow control module is configured to receive a control signal sent by the control analysis module to keep the size of the gas output flow constant; The air control module is configured to open the path of the sample to be measured or the air path according to the control instruction sent by the control analysis module, and convey the aerosol sample gas to be measured or air mixed therein to the TEOM oscillation detection module; The TEOM oscillation detection module is configured to detect the oscillation frequencies of different filter membrane clips when receiving the aerosol sample gas to be measured or air mixed therein and the control signal sent by the control analysis module, and send them to the control analysis module in real time; The control analysis module is configured to obtain the size of the output flow of the gas flow control module according to the average temperature and average air pressure of the current season, and send a control signal to the gas flow control module; at the same time, according to the oscillation frequencies of different filter membrane clips detected by the TEOM oscillation detection module, obtain the mass concentration of aerosol particles per unit time in real time.

2. The real-time aerosol mass concentration detection system based on TEOM according to claim 1, wherein The air control module includes a device housing and an air delivery pipeline and a pipeline for the sample to be measured connected to the device housing; Two air inlets and one air outlet are provided on the device housing; one air inlet is connected to the air delivery pipeline, the other air inlet is connected to the pipeline for the sample to be measured, and the air outlet is connected to the TEOM oscillation detection module through a pipeline; Solenoid valves A and B are respectively provided on the air delivery pipeline and the pipeline for the sample to be measured, and the solenoid valves A and B are respectively connected to the control analysis module; An air filter is further provided on the air delivery pipeline.

3. The real-time detection system for aerosol mass concentration based on TEOM according to claim 1, characterized in that The TEOM oscillation detection module includes: an oscillation detection tube, a laser Doppler vibrometer, a filter membrane clip, a solenoid coil, and an AC power supply; The oscillation detection tube is arranged perpendicular to the ground, one end of the oscillation detection tube is an oscillation end, which is connected to the air outlet of the air control module, and the other end is an air outlet end, which is connected to the gas flow control module; There are two solenoid coils, which are symmetrically arranged outside the oscillation end of the oscillation detection tube through fixed brackets respectively, and are respectively connected to the AC power supply; A filter slot is provided inside the oscillation end of the oscillation detection tube, and the filter membrane clip is installed in the filter slot to realize the replacement of filter membrane clips with different masses during the detection process; The laser Doppler vibrometer is connected to the control analysis module, and the emission direction of the laser detection end of the laser Doppler vibrometer is arranged corresponding to the outer wall of the oscillation end of the oscillation detection tube.

4. The real-time aerosol mass concentration detection system based on TEOM according to claim 3, characterized in that, The oscillation detection tube is of a conical structure, and the inner wall of the oscillation end is coated with a nano-hollow glass microsphere coating.

5. The real-time aerosol mass concentration detection system based on TEOM according to claim 1, characterized in that, The gas flow control module includes: a suction pump, a gas flow controller, and an air filter connected in sequence; A flow meter and a solenoid valve are provided on the pipeline between the gas flow controller and the air filter; the input end of the air filter is connected to the air outlet end of the TEOM oscillation detection module; The air extraction pump and the gas flow controller are both connected to the control and analysis module. When the control and analysis module sends a control signal, after the air extraction pump receives the air extraction pump control signal, the air extraction pump starts and provides the air extraction power; the gas flow controller receives the gas flow controller control signal, and the gas flow controller adjusts the opening and closing degree of the solenoid valve to make the value of the flow meter equal to the value set by the control and analysis module, so as to control the gas flow rate.

6. The control method of a real-time detection system for aerosol mass concentration based on TEOM according to claim 1, characterized in that, It includes the following steps: 1) The gas flow controller receives the control signal sent by the control and analysis module to keep the gas output flow rate constant; 2) Obtain the elastic coefficient of the oscillation detection tube in the TEOM oscillation detection module; 3) Detect the oscillation frequency of the air through a laser Doppler vibrometer and send the detected oscillation frequency of the air to the control and analysis module; The laser Doppler vibrometer of the TEOM oscillation detection module detects the oscillation frequency of the sample gas to be measured and sends the detected oscillation frequency of the sample gas to be measured to the control and analysis module; 4) Replace N groups of filter membrane clips with different masses. Each time a filter membrane clip is replaced, execute step 3), and after sending all the detected oscillation frequency data to the control and analysis module, execute step 5); 5) The control and analysis module analyzes according to all the oscillation frequency data to obtain the aerosol particle mass concentration in the sample gas to be measured.

7. According to the control method of a TEOM-based aerosol mass concentration real-time detection system as described in claim 6, step 1), specifically: The control and analysis module obtains the output flow rate of the gas flow control module according to the currently set average temperature and average air pressure of the user, specifically: The control and analysis module controls the output flow rate of the gas flow control module to be: Among them, FlowSP1 is the target volume flow rate of the gas flow controller, TempAVG is the average temperature set by the user, TempSTD is the standard temperature, PAVG is the seasonal average air pressure input by the user, and PSTD is the standard pressure; Compare the measured value of the flow meter on the current gas flow controller with the output flow rate FlowSP0, and adjust the opening and closing degree of the solenoid valve on the gas flow control module to keep the output flow rate of the gas flow controller constant at FlowSP0.

8. According to the control method of a TEOM-based aerosol mass concentration real-time detection system as described in claim 6, step 2), specifically: Measure the vibration frequency of the test gas passing through the filter membrane clip as the final frequency F1, and the laser Doppler vibrometer detects the oscillation frequency of the air passing through the filter membrane clip as the initial frequency F0; Then the elastic coefficient of the oscillation detection tube is: Among them, dm is the mass of the test sample gas passing through the filter membrane clip - the mass of the filter membrane clip passing through the air.

9. According to the control method of a TEOM-based aerosol mass concentration real-time detection system as described in claim 6, step 3) specifically is: Air is introduced as a control group. The control and analysis module controls the solenoid valve B to close and the solenoid valve A to open. Then, the air flows out along one of the air inlet outlets through the air filter and enters the TEOM oscillation detection module. The air passes through the filter membrane clip of the TEOM oscillation detection module. The control and analysis module controls the coil to be energized. The laser Doppler vibrometer detects the oscillation frequency of the air and sends the detected oscillation frequency of the air to the control and analysis module. After the laser Doppler vibrometer detects the oscillation frequency of the air, the control and analysis module controls the solenoid valve A to close and the solenoid valve B to open. Then, the sample gas to be measured flows out at the other air inlet along the air flow direction and enters the TEOM oscillation detection module. The sample gas to be measured passes through the filter membrane clip of the TEOM oscillation detection module. The control and analysis module controls the coil to be energized. The laser Doppler vibrometer detects the oscillation frequency of the sample gas to be measured and sends the detected oscillation frequency of the sample gas to be measured to the control and analysis module.

10. The control method of a real-time aerosol mass concentration detection system based on TEOM according to claim 6, wherein step 5) is specifically as follows: The control and analysis module respectively obtains F1 - FN as the oscillation frequency data under N groups of different mass filter membrane clips collected by the Doppler laser vibrometer; According to Obtain the mass change amounts corresponding to N groups of different quality filter membrane clips respectively, namely: dm1 - dmN; Fit dm1 - dmN to obtain the power-law trend curve of the mass change amount, that is: Substitute dm1 - dmN into M0, and calculate K2 and n according to the measured FN and F0 each time; Substitute the obtained K2 and n into the following formula, then the aerosol particle mass concentration in the sample gas to be measured: Among them, T is the air flow sampling duration controlled by the control and analysis module, K2 is the fitting calculation coefficient of each filter membrane clip, n is the fitting calculation power of each filter membrane clip, K0 is the elastic coefficient of the oscillation detection tube without load; F0 is the oscillation frequency of the air passing through the filter membrane clip, F1 is the vibration frequency of the sample gas to be measured passing through the filter membrane clip, FlowSP1 is the set-point volume flow, TempAVG is the average temperature set by the user, TempSTD is the standard temperature, PAVG is the seasonal average air pressure set by the user, and PSTD is the standard pressure.

Images