Solute concentration indirect detection system and method based on particulate matter sensor

Abstract

The invention belongs to the technical field of aerosol measurement, and particularly relates to a system and a method for indirectly detecting solution solute concentration based on a particulate matter sensor. The system is mainly composed of a liquid storage tank, an aerosol generating device, a drying treatment unit and a particulate matter sensor. The method comprises the following steps: during detection, firstly, putting a solution to be detected into a liquid storage tank, carrying out atomization treatment by an aerosol generator, and converting a liquid sample to be detected into uniform aerosol particles; then carrying out dehydration treatment through a drying pipe to form dry solid particles; and finally, detecting the mass concentration of the particulate matters in the dry aerosol in real time by adopting a particulate matter sensor, and calculating the mass of the solute contained in the solution on the basis of a mass conservation principle in combination with the atomization flow parameter of the aerosol generator and the volume of the solution to be detected consumed in the atomization process. Non-contact real-time monitoring is achieved, the problem of solution pollution of a traditional electrode method is avoided, and the method has wide application prospects in the fields of environment monitoring, pharmacy, food safety detection and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of aerosol measurement, and particularly relates to a solute concentration detection system and method. Background Art

[0002] As a core analysis technology in fields such as environmental monitoring, biopharmaceuticals, and the food industry, the accuracy and convenience of solution concentration detection directly affect product quality control and process optimization efficiency. Existing detection systems generally face three problems: "accuracy - cost - universality". Although high - end instruments based on chromatography can achieve ultra - high accuracy of ±0.1%, the cost of a single device is high, and professional operators are required for maintenance; although electronic detection devices such as conductivity sensors and ion - selective electrodes have the ability of real - time online monitoring, they are easily affected by environmental factors such as solution pH fluctuations and co - existing ion interferences; while simple devices such as refractometers and densitometers are easy to operate, but their limitations in relying on physical property databases lead to a detection failure rate of up to 40% for new compounds and multi - component mixtures. Especially in scenarios such as high - throughput detection and extreme working conditions, traditional methods have significant shortcomings in terms of response speed, anti - interference ability, and equipment durability. Therefore, developing a new generation of concentration detection technology with low cost, high robustness, and broad applicability has become the key breakthrough to break through the industry's productivity bottleneck and achieve precise intelligent manufacturing. Summary of the Invention

[0003] In view of the deficiencies of the existing technology, the purpose of the present invention is to provide an indirect detection system and method for solute concentration based on a particulate sensor with low detection cost, high robustness, and wide applicability.

[0004] The present invention realizes high - precision, non - contact in - situ concentration detection by quantitatively converting a liquid to - be - measured solution into solid aerosol particles, combining a particulate sensor with a mass conservation algorithm, and is applicable to high - precision solute concentration analysis in fields such as environmental pollutant monitoring, pharmaceutical process quality control, and food safety detection.

[0005] The indirect detection system for solute concentration based on a particulate sensor provided by the present invention specifically includes a liquid storage tank, an aerosol generating device, a drying treatment unit, and a particulate sensor; wherein:

[0006] The liquid storage tank is used for storing the liquid to be measured, and a capacitive liquid level sensor can be optionally integrated inside to calculate the solution consumption by real - time monitoring of the liquid level change.

[0007] The body of the liquid storage tank is made of quartz or polytetrafluoroethylene and can withstand the corrosion of strong acids, strong alkalis, and organic solvents.

[0008] The aerosol generating device atomizes the liquid to be measured into aerosol, with the requirements: the atomization particle size range is 20 - 200 nm, and the gas flow control accuracy is ±2%.

[0009] The aerosol generating device specifically uses a constant flow collision type aerosol generator or an ultrasonic nebulizer, etc., which are atomizers that can meet the conditions. The constant flow collision type generator atomizes the solution into aerosol particles with a particle size of 20 - 200 nm through the Venturi effect and a microporous collision plate. The gas flow rate is measured by a high-precision mass flow controller (MFC), and the fluctuation range is less than ±0.1 L / min; the ultrasonic nebulizer uses a piezoelectric ceramic transducer to achieve stable atomization of the solution, and the adjustable range of the atomization amount is 0.1 - 5 mL / min.

[0010] A liquid reflux device can also be selectively provided between the liquid storage tank and the aerosol generating device to recover large droplets that are not fully atomized, which is specifically determined according to the selected aerosol generating device.

[0011] The drying treatment unit dries the aerosol particles to volatilize the solvent in the aerosol to form solid particulate matter.

[0012] The drying treatment unit specifically uses a multi-stage diffusion drying tube or a nafion tube, etc.

[0013] A diverter can also be selectively provided between the aerosol generating device and the drying treatment unit to balance the flow rate difference between the particulate matter sensor and the aerosol generating device, which is specifically determined according to the actual situation.

[0014] The particulate matter sensor is used to detect the aerosol-containing gas stream after drying.

[0015] Specifically, optical scattering or β-ray attenuation detection principles, etc., can be used. The detection sensitivity is related to different monitoring principles. Therefore, for different monitoring methods, there will be certain differences in the measured mass concentration deviation.

[0016] The present invention also provides an indirect detection method for the solute concentration of the solution based on the above system. The specific process is as follows:

[0017] First, inject the solution to be measured into the liquid storage tank, start the aerosol generating device, generate aerosol particles with uniform particle size through the aerosol generating device, the gas flow rate is measured by a mass flowmeter, and the atomization time is 5 - 30 minutes, which can be appropriately adjusted according to the size of the solute concentration of the solution;

[0018] Subsequently, the aerosol enters the drying treatment unit for solvent removal to volatilize the solvent in the aerosol to form solid particulate matter; the dried particulate matter is continuously detected by the particulate matter sensor for the mass concentration (Cp); specifically, the solute concentration is calculated based on the law of conservation of mass. The formula is:

[0019]

[0020] C p is the solute concentration of the solution to be measured, Cg C is the aerosol mass concentration measured by the particulate matter sensor (unit: mg / L), Q is the gas volume, and V is the sample consumption. The gas volume Q is calculated by measuring the gas flow rate (unit: L / min) of the aerosol generation device and accurately recording the atomization duration (unit: min). There are two specific methods for calculating the gas volume Q:

[0021] ① Weighing method: Use a high-precision electronic balance to measure the total mass change of the liquid storage tank (1), and convert the volume difference according to the solution density. The solution density is treated as the density of water;

[0022] ② Liquid level monitoring method: Integrate a capacitive liquid level sensing module in the liquid storage tank (1) to continuously monitor the change in the liquid level height, and calculate it by multiplying with the cross-sectional area of the liquid storage tank.

[0023] The main advantages of the present invention are:

[0024] The innovation of the present invention is to convert the liquid-phase concentration detection into aerosol particulate matter detection, realizing non-contact real-time monitoring and avoiding the solution pollution problem of the traditional electrode method. It has broad application prospects in the fields of environmental monitoring, pharmaceuticals, food safety detection, etc.

[0025] The present invention has broad applicability and can be used for detecting unknown solute solutions. In addition, the detection cost is low and no consumables are required. Brief Description of the Drawings

[0026] Figure 1 It is a structural diagram of the indirect detection system for solute concentration of the present invention.

[0027] Figure 2 It is a structural diagram of the indirect detection system for solute concentration in Example 1.

[0028] The reference numerals in the figure: 1 is the liquid storage tank, 2 is the aerosol generation device, 3 is the drying treatment unit, 4 is the particulate matter sensor, 5 is the diverter, 6 is the first pressure reducing valve, 7 is the second pressure reducing valve, 8 is the SMC filter, 9 is the air compressor, and 201 is the liquid return pipe. Detailed Embodiments

[0029] The present invention will be further described below in conjunction with the drawings and embodiments:

[0030] Example 1: Refer to Figure 2 It includes: the liquid storage tank 1, the aerosol generation device 2, the drying treatment unit 3, the particulate matter sensor 4, the diverter 5, the first pressure reducing valve 6, the second pressure reducing valve 7, the SMC filter 8, the air compressor 9, and the liquid flow pipe 201.

[0031] The liquid storage tank 1 is a liquid storage tank made of polytetrafluoroethylene.

[0032] The aerosol generating device 2 is a constant-flow collision type aerosol generator. A high-pressure air source is provided by an air compressor 9, and oil, water, and dust in the compressed air are removed through an SMC filter 8. A No. 2 pressure reducing valve 7 is used to adapt to an appropriate air pressure for liquid atomization. In this case, the air pressure is 0.4 MPa.

[0033] The drying treatment unit 3 is a diffusion drying tube. Its tube side is a through-screen mesh, and the shell side is filled with water-absorbing silica gel.

[0034] The particulate matter sensor 4 is a beta-ray sensor. The dried aerosol adheres to the built-in filter membrane of the particulate matter sensor, and the mass of the particulate matter adhering to the filter membrane is deduced by detecting the attenuation of the beta-ray before and after sampling by the particulate matter sensor.

[0035] The flow divider 5 includes a tube side in the middle and a shell side on the outside. It is used to balance the airflow difference between the aerosol generator and the particulate matter sensor. In this case, the atomization flow rate of the aerosol generator 2 at 0.4 MPa is 3 L / min, and the extraction flow rate of the particulate matter sensor 4 is 16.7 L / min.

[0036] The aerosol generating device 2 is connected to the liquid storage tank through a corrosion-resistant hose. The Bernoulli effect is formed by the high-pressure air source to extract the liquid to be measured for atomization, and the unqualified large-particle aerosol flows back through the liquid return pipe 201.

[0037] The aerosol formed by the aerosol generator 2 directly enters the tube side of the flow divider. The clean air used to balance the flow difference is filtered by the air compressor 9 through the SMC filter 8 and then enters the shell side of the flow divider through the No. 1 pressure reducing valve 7. The two airflows are evenly mixed here and then enter the drying treatment unit 3, and then are detected by the particulate matter sensor 4.

[0038] The detection method in this example is as follows:

[0039] Step 1: Turn on the air compressor 9 to make it have sufficient air pressure. Inject a known volume of the liquid to be measured into the liquid storage tank and record the liquid level height. Ensure that the shell side of the drying treatment unit 3 is filled with dry silica gel;

[0040] Step 2: Set the air pressure of the No. 1 pressure reducing valve to 0.4 MPa and the No. 2 pressure reducing valve to a slightly positive pressure. At the same time, start the particulate matter sensor 4 and start timing;

[0041] Step 3: Stop the aerosol generating device and the particulate matter sensor simultaneously after running for 15 minutes;

[0042] Step 4: The particulate matter sensor 4 reads and calculates the mass of the dry aerosol. Manually read the liquid level height of the liquid storage tank after the experiment, and calculate the sample consumption according to the liquid level height difference before and after the experiment;

[0043] Step 5: Calculate the solute mass concentration according to the formula.

Claims

1. An indirect detection system for solute concentration based on a particulate matter sensor, characterized in that, Specifically, it includes a liquid storage tank, an aerosol generating device, a drying treatment unit, and a particulate sensor; among which: The liquid storage tank is used to store the liquid to be measured, and a capacitive liquid level sensor can be optionally integrated inside to monitor the change of the liquid level in real time and calculate the consumption of the solution; The aerosol generating device is used to atomize the liquid to be measured into aerosol. Requirements: the atomization particle size range is 20 - 200 nm, and the gas flow control accuracy is ±2%; The drying treatment unit is used to dry the aerosol particles to volatilize the solvent in the aerosol to form solid particles; The particulate sensor is used to detect the aerosol-containing gas flow after drying.

2. The solute concentration indirect detection system according to claim 1, wherein A liquid reflux device is provided between the liquid storage tank and the aerosol generating device to recover the large liquid droplets that are not fully atomized.

3. The solute concentration indirect detection system according to claim 2, characterized in that, A diverter is provided between the aerosol generating device and the drying treatment unit to balance the flow difference between the particulate sensor and the aerosol generating device.

4. The indirect solute concentration detection system according to claim 1, 2 or 3, characterized in that The aerosol generating device specifically adopts a constant-current collision type aerosol generator or an ultrasonic nebulizer; the constant-current collision type generator atomizes the solution into aerosol particles with a particle size of 20 - 200 nm through the Venturi effect and a microporous collision plate, and the gas flow is measured by a high-precision mass flow controller (MFC), and the fluctuation range is less than ±0.1 L / min; the ultrasonic nebulizer uses a piezoelectric ceramic transducer to achieve stable atomization of the solution, and the adjustable range of the atomization amount is 0.1 - 5 mL / min.

5. The solute concentration indirect detection system according to claim 4, wherein The drying treatment unit specifically adopts a multi-stage diffusion drying tube or a nafion tube.

6. The solute concentration indirect detection system according to claim 5, characterized in that A diverter is provided between the aerosol generating device and the drying treatment unit to balance the flow difference between the particulate sensor and the aerosol generating device.

7. The indirect solute concentration detection system according to claim 6, wherein, The particulate sensor adopts the optical scattering or β-ray attenuation detection principle.

8. An indirect detection method for solute concentration of the detection system according to any one of claims 1-7, characterized in that, The specific process is as follows: First, inject the solution to be measured into the liquid storage tank, start the aerosol generating device, generate aerosol particles with uniform particle size through the aerosol generating device, measure the gas flow by a mass flowmeter, and the atomization time is 5 - 30 minutes; Subsequently, the aerosol enters the drying treatment unit for solvent removal, and the solvent in the aerosol volatilizes to form solid particles; The particulate sensor detects the mass concentration (Cp) of the dried particles in real time, and the calculation formula is: Among them, C p is the solute concentration of the solution to be measured, C g is the aerosol mass concentration measured by the particulate matter sensor, unit: mg / L, Q is the gas volume, and V is the sample consumption; the gas volume Q is calculated by measuring the gas flow rate of the aerosol generating device, unit: L / min, and accurately recording the atomization duration, unit: min.

9. The indirect solute concentration detection method according to claim 8, characterized in that, There are two methods to calculate the volume of gas Q: ① Weighing method: Use a high-precision electronic balance to measure the total mass change of the liquid storage tank, convert the volume difference according to the solution density, and the solution density is treated according to the density of water; ② Liquid level monitoring method: Integrate a capacitive liquid level sensing module in the liquid storage tank to continuously monitor the change of the liquid level height, and calculate it by multiplying with the cross-sectional area of the liquid storage tank.

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