Calibration device of high-voltage particle counter

Abstract

The utility model provides a calibration device for a high pressure particle counter, which comprises a high pressure aerosol generator, a dryer, a differential electric classifier and an aerosol mixing box which are connected in sequence, the input end of the high pressure aerosol generator is connected with a clean compressed air source, the aerosol mixing box is further connected with a pressure gauge and a pressure controller, and the pressure controller is connected with the dryer. The input end of the pressure controller is connected with clean compressed air, the aerosol mixing box is provided with two branch outlets, one branch outlet is connected with a standard particle counter through a high-pressure diffuser, and the other branch outlet is connected with a calibrated high-pressure particle counter. According to the utility model, the high-pressure particle counter can be calibrated, an aerosol sample with stable concentration is provided, and the stability and the reliability of a calibration result are improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to aerosol particle measurement technical field especially relates to a kind of calibration device of high pressure particle counter. BACKGROUND

[0002] Compressed air is widely used in petroleum, chemical industry, metallurgy, power, machinery, light industry, textile, automobile manufacturing, electronics, food, medicine, biochemical, national defense, scientific research and other industries as a power source and medium carrier.The cleanliness level of compressed air is an important guarantee for the safe use of equipment and the quality of production products.Currently, the International Organization for Standardization (ISO) has issued nine national standards for compressed air quality (ISO8573-1~ISO8573-9), which cover compressed air pollutants and cleanliness levels.In the national standard GB / T 13277.1-2008 "Compressed Air Part 1: Contaminant Cleanliness Levels", it is introduced that the main pollutants in compressed air are solid particles, moisture and oil, and these three pollutants are the main parameter indicators for measuring the cleanliness level of compressed air.

[0003] Particles as the main pollutants play an important role in the evaluation of the grade of compressed air quality.In ISO8573-4 "Compressed Air-Determination of Solid Particles", it is introduced that through gravimetric analysis, microscopic examination, laser particle counter and scanning electron microscope (SEM) analysis, a method for testing particle contamination in compressed air can be used, however, gravimetric analysis, microscopic examination and scanning electron microscope method all need to collect the total number of particles per unit volume in advance using a filter membrane, and then go to the laboratory for weighing or microscopic counting, which is time-consuming and laborious, and the operability is not strong, the human factor interference is too large, and the distribution and concentration change of particle size cannot be reflected in time.Therefore, high pressure particle counters appear on the market, which can realize online real-time detection of particles in compressed air.In order to ensure the accuracy and reliability of the measurement results of high pressure particle counter, it is particularly important to calibrate it regularly.

[0004] At present, China has introduced "GB / T 6167-2007 Dust Particle Counter Performance Test Method" and "JJF1190-2008 Dust Particle Counter Calibration Specification", which introduces the calibration scheme of the particle counter, that is, the monodisperse polystyrene latex standard particle is atomized to generate monodisperse aerosol particles, and the value traceability of the standard particle count and the detected particle counter is realized through flow regulation matching. The existing calibration method is only applicable to the traditional dust particle counter, which mainly supplies clean air to the measured particle counter through the homogenizing box under positive pressure, but the pressure is generally tens of kilopascals, while the pressure source of compressed gas is generally (0-1.0) MPa, and the particle size measurement range is between 0.3 and 10.0 microns. The lower limit of the working pressure of the high-pressure particle counter on the market is 0.3 MPa. The internal working principle of the high-pressure particle counter is to directly or through a high-pressure diffuser to transmit the detected gas into the particle counter measurement cabin for particle analysis and measurement. The existing particle counter measurement method cannot meet the calibration requirements of the high-pressure particle counter, especially in the particle calibration of the high-pressure particle counter. How to generate a high-pressure and stable monodisperse aerosol becomes a difficulty in the calibration process. Practical new type content

[0005] The technical problem to be solved by the utility model lies in providing a calibration device of a high-pressure particle counter to realize efficient calibration of the high-pressure particle counter.

[0006] The utility model is realized in this way: a calibration device of a high-pressure particle counter, including mass flow meter, high-pressure aerosol generator, dryer, differential electric fractionator and aerosol homogenizing box which are connected in sequence, the input end of mass flow meter is connected clean compressed air;

[0007] The input end of aerosol homogenizing box is also connected with a pressure controller, the input end of pressure controller is connected clean compressed air, the aerosol homogenizing box is equipped with two branch outlets, one is connected with standard particle counter through high-pressure diffuser, and the other is connected with high-pressure particle counter to be calibrated, the aerosol homogenizing box is also equipped with pressure gauge.

[0008] Further, the calibration device further includes a compressed air supply device for obtaining clean compressed air, and the compressed air supply device includes an air compressor, a cold dryer, an efficient filter and a solenoid valve connected in sequence, and the input end of the pressure controller and the input end of the mass flow meter are respectively connected with the solenoid valve of the compressed air supply device to obtain clean compressed air.

[0009] Further, an aerosol electrostatic neutralizer is further arranged between the dryer and the differential electric fractionator.

[0010] Further, the aerosol mixing box comprises a stainless steel cylindrical cavity, a sampling inlet, a pressure regulating inlet and a sampling outlet, the front end of the cylindrical cavity is provided with a first tapered space and a second tapered space, the two tapered spaces are connected into a sandglass-shaped cavity, the sampling inlet is provided with a tapered head, the sampling inlet and the pressure regulating inlet are respectively inserted into the first tapered space, and the sampling inlet and the pressure regulating inlet are vertically arranged, the tapered head is located between the first tapered space and the second tapered space, the aerosol mixing box is connected with the differential electric classifier through the sampling inlet, and the aerosol mixing box is connected with the voltage controller through the pressure regulating inlet.

[0011] Further, the dryer adopts a heating pipe with a length of 60cm and an inner diameter of 8mm, and the aerosol particles output by the high-pressure aerosol generator are dehumidified through the design mode of heating the pipe.

[0012] Further, the two branch outlets of the aerosol mixing box are connected through a flow shunt, the flow shunt is made of 316 stainless steel, the flow shunt comprises a ⅜-inch straight pipe inlet and at least two ¼-inch outlet branches, the straight pipe inlet is connected with the aerosol mixing box, one of the outlet branches is connected with the calibrated high-pressure particle counter, and the other outlet branch is connected with the high-pressure diffuser, and the high-pressure diffuser is connected to the standard particle counter.

[0013] The utility model has the advantages that: by designing a high-pressure particle counter calibration device, aerosol samples with a peak particle size in the range of <2μm and a number concentration of not less than (3000-10000) pieces / L can be generated, the concentration stability of the aerosol samples is better than 2% / 20min, the output pressure is not less than 0.3MPa, and the calibration requirements of the high-pressure particle counter in the flow pressure range (0.1-1.0) MPa and the flow range (0.1-5.0) L / min can be met. BRIEF DESCRIPTION OF DRAWINGS

[0014] The utility model will be further described below with reference to the drawings and in combination with the embodiments.

[0015] Fig. 1 It is a structural schematic view of the calibration device of the high-pressure particle counter.

[0016] Fig. 2 It is a structural schematic view of the compressed air supply device.

[0017] Fig. 3 It is a structural schematic view of the aerosol mixing box.

[0018] Explanation of reference numerals:

[0019] 1, mass flow meter, 2, high pressure aerosol generator, 3, dryer, 4, differential electrical classifier, 5, aerosol mixing box, 51, stainless steel cylindrical cavity, 52, sampling inlet, 53, pressure regulating inlet, 54, sampling outlet, 511, first conical space, 512, second conical space, 6, pressure controller, 7, high pressure diffuser, 8, compressed air supply device, 81, air compressor, 82, cold dryer, 83, high efficiency filter, 84, electromagnetic valve, 9, aerosol electrostatic neutralizer, 10, flow splitter, 11, pressure gauge, A, standard particle counter, B, high pressure particle counter to be calibrated. DETAILED DESCRIPTION

[0020] Referring to Figs. 1 to 3 , the utility model provides a kind of calibration device of high pressure particle counter, as Fig. 1 It is shown that it comprises the mass flow meter 1 of sequentially connected high pressure aerosol generator 2, dryer 3, differential electrical classifier 4 and aerosol mixing box 5, and the input end of the mass flow meter 1 is connected clean compressed air;

[0021] The input end of the aerosol mixing box 5 is also connected with a pressure controller 6, the input end of the pressure controller 6 is connected clean compressed air, and the aerosol mixing box 5 is equipped with two branch outlets, one is connected with standard particle counter A by high pressure diffuser 7, and the other is connected with high pressure particle counter B to be calibrated, and the aerosol mixing box is also equipped with pressure gauge 11, and the pressure change condition inside aerosol mixing box is directly observed by pressure gauge.

[0022] Preferably, the calibration device further comprises compressed air supply device 8 for obtaining clean compressed air, as Fig. 2 It is shown that the compressed air supply device 8 comprises air compressor 81, cold dryer 82, high efficiency filter 83 and electromagnetic valve 84 connected in sequence, and the input end of the pressure controller 6 and the input end of the mass flow meter 1 are respectively connected with the electromagnetic valve 84 of compressed air supply device 8 to obtain clean compressed air.

[0023] Among them, the moisture and particles in clean compressed air are removed by cold dryer and high efficiency filter, and become clean compressed gas, and the electromagnetic valve controls the on-off of gas path.

[0024] Preferably, the dryer 3 and the differential electrical classifier 4 are further provided with an aerosol electrostatic neutralizer 9.

[0025] Preferably, as Fig. 3As shown, the aerosol mixing box 5 includes a 316 stainless steel cylindrical cavity 51, a sampling inlet 52, a pressure regulating inlet 53, and a sampling outlet 54. The front end of the cylindrical cavity 51 is provided with a first tapered space 511 and a second tapered space 512, which are connected to form a sandglass-shaped cavity. The sampling inlet 52 is provided with a tapered head 521. The sampling inlet 52 and the pressure regulating inlet 53 are respectively inserted into the first tapered space 511. The sampling inlet 52 and the pressure regulating inlet 52 are vertically arranged. The tapered head 521 is located between the first tapered space 511 and the second tapered space 512. The aerosol mixing box 5 is connected to the differential electrical classifier 4 through the sampling inlet 52, and is connected to the voltage controller 6 through the pressure regulating inlet 42. The sandglass-shaped cavity forms a jet nozzle. Single-piece aerosol enters the cavity from the horizontal direction, and the gas pressure controller enters the gas from the vertical direction. The flow of the gas pressure controller does not interfere with the flow of the mixing and diluting device. The interfaces of the aerosol mixing box are sealed, and the internal wall gloss level is greater than or equal to HL level.

[0026] Preferably, the pressure in the aerosol mixing box is controlled within the range of (0~1.0) MPa. Specifically, it can be set to 0.3 MPa.

[0027] Preferably, the inlet flow of the high-pressure aerosol generator is 0~4 L / min. The actual value is set to meet the particle count calibration of two devices, and is generally set to 2~3 L / min. The input pressure of the high-pressure aerosol generator can be set to 0.8 MPa.

[0028] Preferably, the dryer 3 adopts a heating tube with a length of 60 cm and an inner diameter of 8 mm. The aerosol particles output by the high-pressure aerosol generator are dehumidified by heating the tube. The heating temperature is automatically controlled and adjusted, and is generally set to 80℃.

[0029] Preferably, the two branch outlets of the aerosol mixing box are connected through a flow diverter 10. The flow diverter is made of 316 stainless steel. The flow diverter includes a ⅜ inch straight pipe inlet and at least two ¼ inch outlet branches. The straight pipe inlet is connected to the aerosol mixing box. One of the outlet branches is connected to the high-pressure particle counter B to be calibrated. The other outlet branch is connected to the high-pressure diffuser 7, which is further connected to the standard particle counter A. An exhaust port is arranged on the high-pressure diffuser for emptying. A filter is further arranged on the exhaust port. The flow diverter can ensure smooth flow distribution of the fluid and meet the gas flow of more than 10 L / min.

[0030] The working principle of the high-pressure particle counter calibration device is as follows: filtered clean compressed air is punched into an aerosol generator, monodisperse polystyrene particle standard substance in the device is atomized and dried by a dryer, aerosol particles are generated, then the aerosol sample containing particles passes through an aerosol electrostatic neutralizer to generate stable and monodisperse submicron aerosol particles, then passes through a differential electric classifier, the aerosol particles are classified based on electric migration classification mobility, the aerosol is mixed and uniformly dispersed by flowing through an aerosol mixing box, then clean compressed air is punched into the aerosol mixing box by a pressure controller, the fluid pressure is monitored in real time by the pressure controller and adjusted according to the set parameters, so that the fluid pressure in the aerosol mixing box is controlled within the pressure range of the high-pressure particle counter to be calibrated, the high-pressure fluid in the branch connected with the standard particle counter is diffused into low-pressure fluid by a high-pressure diffuser to adapt to the working requirements of the standard particle counter, a plurality of experimental data are obtained by repeating the experiment several times and repeating the experiment several times after exchanging the sampling port, and finally the calibration result of the high-pressure particle counter is obtained by calculating and directly comparing the data of the high-pressure particle counter to be calibrated and the data of the standard dust particle counter.

[0031] The calibration method of the high-pressure particle counter comprises the following steps:

[0032] (1) pure water and a particle size standard substance are added to a high-pressure aerosol generator, a mass flow meter, the high-pressure aerosol generator, a dryer, an aerosol electrostatic neutralizer, a differential electric classifier, an aerosol mixing box, a pressure controller, a high-pressure particle counter to be calibrated, a high-pressure diffuser and a standard particle counter are turned on; the average particle size of the particle size standard substance is consistent with the lower limit of particle size measurement of the high-pressure particle counter to be calibrated (for example, 0.3 μm particle size standard substance (GBW(E)120063, average particle size value is 280 nm, and uncertainty is 8 nm) is selected); the counting mode of the standard dust particle counter is set to cumulative counting mode; (specifically, the high-pressure particle counter to be calibrated and the standard particle counter can be selected according to actual needs, for example, the Kanomax dust particle counter 3889 can be used as the standard particle counter, and the high-pressure particle counter of the American PMS company HPGP-101-CPDS-E type is used as the high-pressure particle counter to be calibrated)

[0033] (2) the pressure and flow of the clean compressed air source are adjusted, the flow and pressure of the high-pressure aerosol generator are adjusted, the pressure in the aerosol mixing box is controlled in the working pressure range of the high-pressure particle counter to be calibrated by the pressure controller, and the particle number concentration in the aerosol mixing box is controlled in the range of (3000-10000) pieces / L;

[0034] (3) After the aerosol concentration is stable, record the average values of the standard particle counter and the calibrated high-pressure particle counter in 1 min, respectively, denoted as and Repeat the above measurement a total of 5 times, then reverse the positions of the calibrated high-pressure particle counter and the standard particle counter connected with the high-pressure diffuser, repeat the above measurement 5 times, and calculate the average values of the 10 measurement results of the two counters respectively, denoted as and ; Calculate the efficiency of the calibrated high-pressure particle counter at this particle size according to the following formula ;

[0035] ;

[0036] In the formula:

[0037] is the particle counting efficiency of the calibrated high-pressure particle counter for measuring aerosol samples with particle size D;

[0038] is the particle counting efficiency of the standard particle counter for measuring aerosol samples with particle size D; (wherein is a known value in the traceability process, directly given by the certificate)

[0039] (4) Select another particle size standard substance, whose average particle size should be between 1.5-2.0 times the lower limit of the particle size of the calibrated high-pressure particle counter (generally 0.5 μm particle size standard substance (GBW12031, average particle size value is 487.2 nm, uncertainty is 4.1 nm)), repeat the methods in steps (1)-(3) to obtain the particle counting efficiency of the calibrated high-pressure particle counter at this particle size;

[0040] (5) Calculate the particle counting repeatability of the calibrated high-pressure particle counter under the two particle size standard substances respectively according to the following formula ;

[0041] ;

[0042] In the formula:

[0043] is the measurement repeatability of the calibrated high-pressure particle counter;

[0044] n is the number of measurements, n=10.

[0045] The setting requirements of each instrument and equipment in the calibration device are as follows:

[0046] The pressure controller has a gas pressure control range of 0-1 MPa, a control precision of ±0.50% F.S, and is generally set to 0.3 MPa.

[0047] The high-pressure aerosol generator has a back pressure of up to 1 MPa and a flow rate of up to the maximum flow rate.

[0048] 250 l / h, and for 0.5 μm PSL standard particles, the maximum atomized particle concentration is 5×105 / cm3. In actual use, the atomized particle concentration is mainly determined by the original standard particle liquid concentration, gas pressure and gas flow rate. In use, the atomized concentration is generally controlled to be (3000-10000) particles / L.

[0049] The aerosol electrostatic neutralizer uses soft X-rays inside, has a flow rate range of 0-5 L / min, has a bipolar charge neutralization capability, ensures the charge balance distribution of aerosol particles, prevents the mutual condensation of particles, and can effectively ensure the stability and uniformity of the aerosol particle concentration.

[0050] The differential electrical classifier can screen monodisperse particles with a particle size range of 10 nm to 1 μm, and can ensure the dispersion of the measured particles. The differential electrical classifier can be a model 3938L52 differential electrical classifier of the American TSI company.

[0051] The mass flow meter has a pressure of 3 MPa and a maximum flow rate of 10 L / min, and a flow control precision of ±1.50% F.S. Since the compressed gas source fluctuates, the mass flow meter is used to control the gas flow rate and pressure of the atomization generator, to ensure the stability of the flow. The fluctuation of the stable flow is less than 0.5%, so as to ensure that the stability of the atomization is controlled within 2%.

[0052] After repeated measurement by the above calibration method, two sets of calibration data are obtained. One set of particles is selected as the lower limit of the measurable particle size of the instrument, and the other set is selected as any particle size within the normal working range of the instrument to calculate the efficiency and repeatability under normal working conditions. The calibration results are obtained by calculation. The calibrated high-pressure particle counter can correct the subsequent measurement data to improve the measurement accuracy of the high-pressure particle counter.

[0053] The high-pressure particle counter calibration device can produce stable high-pressure aerosol samples with a peak particle size in the range of <2 mu m and a number concentration not less than (3000-10000) pieces / L, and the concentration stability of the aerosol samples is better than 2% / 20 min. The calibration device can meet the calibration of the high-pressure particle counter with a flow pressure range of (0.1-1.0) MPa and a flow range of (0.1-5.0) L / min. The aerosol concentration stability is improved, and the reliability of the high-pressure particle counter calibration result is further improved.

[0054] Although the specific embodiments of the utility model are described above, those skilled in the art should understand that the specific examples described by us are only illustrative, and are not used to limit the scope of the utility model, and equivalent modifications and changes made by those skilled in the art in accordance with the spirit of the utility model should be covered within the scope of protection of the claims of the utility model.

Claims

1. A calibration device for a high pressure particle counter, characterized by: The calibration device comprises a mass flow meter, a high-pressure aerosol generator, a dryer, a differential electrical classifier and an aerosol mixing box connected in sequence, an input end of the mass flow meter being connected to clean compressed air; An input end of the aerosol mixing box is also connected to a pressure controller, an input end of the pressure controller being connected to clean compressed air, the aerosol mixing box being provided with two branch outlets, one being connected to a standard particle counter through a high-pressure diffuser, and the other being connected to a calibrated high-pressure particle counter, the aerosol mixing box being further provided with a pressure gauge.

2. A calibration device for a high pressure particle counter as claimed in claim 1, characterized in that: The calibration device further comprises a compressed air supply device for obtaining clean compressed air, the compressed air supply device comprising an air compressor, a cold dryer, a high-efficiency filter and a solenoid valve connected in sequence, the input end of the pressure controller and the input end of the mass flow meter being connected to the solenoid valve of the compressed air supply device to obtain clean compressed air.

3. A high pressure particle counter calibration device as claimed in claim 1, characterized in that: An aerosol electrostatic neutralizer is further arranged between the dryer and the differential electrical classifier.

4. A high pressure particle counter calibration device as claimed in claim 1, characterized in that: The aerosol mixing box comprises a stainless steel cylindrical cavity, a sampling inlet, a pressure regulating inlet and a sampling outlet, the cylindrical cavity being provided with a first tapered space and a second tapered space at a front end, the two tapered spaces being connected to form a sandglass-shaped cavity, the sampling inlet being provided with a tapered head portion, the sampling inlet and the pressure regulating inlet being respectively inserted into the first tapered space, and the sampling inlet and the pressure regulating inlet being arranged vertically, the tapered head portion being located between the first tapered space and the second tapered space, the aerosol mixing box being connected to the differential electrical classifier through the sampling inlet and connected to the voltage controller through the pressure regulating inlet.

5. A high pressure particle counter calibration device as claimed in claim 1, characterized in that: The two branch outlets of the aerosol mixing box are connected through a flow shunt, the flow shunt being made of 316 stainless steel, the flow shunt comprising a ⅜-inch straight pipe inlet and at least two ¼-inch outlet branches, the straight pipe inlet being connected to the aerosol mixing box, one of the outlet branches being connected to the calibrated high-pressure particle counter, and the other outlet branch being connected to the high-pressure diffuser, and the high-pressure diffuser being further connected to the standard particle counter.

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