Fine particle measuring device and measuring method

[0042] Example 1

[0043] See figure 1 , figure 2 as well as image 3 , As shown in the legend, a fine particulate matter measuring device used to detect the content of PM2.5 in the air, including a PM10 collector used to collect air samples 1, used to separate the fine particulate matter in the air sample A PM2.5 cutter 2. A detection device for detecting the content of fine particles in an air sample, a filter for collecting fine particles in an air sample, a dryer for removing moisture in an air sample 7, a For a gas pump 8 for stabilizing the air flow and a diverter device 9 for recycling the purified residual gas, the detection device includes:

[0044] A 1# laser scattering sensor 3, used to measure the scattering intensity of fine particles in air samples;

[0045] A 2# laser scattering sensor 4, used to measure the scattering intensity of fine particles in air samples;

[0046] A signal processor 5 for converting the scattering intensity of the fine particles into a concentration of fine particles;

[0047] The 1# laser scattering sensor 3 and 2# laser scattering sensor 4 include serially connected 1# air channel 31, 2# air channel 41, 1# laser scattering sensor 3 laser module, 2# laser scattering sensor 4 laser module, 1# laser scattering sensor 3 detection module and 2# laser scattering sensor 4 laser module.

[0048] The laser module of the #1 laser scattering sensor 3 includes a #1 laser channel 321 for laser light to pass through, a #1 laser source 322 for emitting laser light and a #1 laser source 322 set at both ends of the #1 laser channel 321 and for absorbing laser light. 的一1#Laser trap 324;

[0049] The laser module of the 2# laser scattering sensor 4 includes a 2# laser channel 421 for laser light passing through, a 2# laser source 422 for emitting laser light and a 2# laser source 422 arranged at both ends of the 2# laser channel 421 for absorbing laser light. 的一2#Laser trap 424;

[0050] The detection module of the 1# laser scattering sensor 3 includes a 1# scattering channel 331 for laser scattering and a 1# laser intensity detection device located at both ends of the 1# scattering channel 331 to detect the scattering intensity of fine particles in the air sample Instrument 332 and a #1 laser catcher 333 for absorbing scattered laser light;

[0051] The detection module of the 2# laser scattering sensor 4 includes a 2# scattering channel 431 for laser scattering and a 2# laser intensity detection device located at both ends of the 2# scattering channel 431 to detect the scattering intensity of fine particles in the air sample Meter 432 and a #2 laser catcher 433 for absorbing scattered laser light.

[0052] The 1# laser channel 321 and the 1# scattering channel 331 and the 1# air channel 31 are provided with a 1# measured intersection space 34;

[0053] The intersection area 35 of the incident light from the 1# laser source 322 and the scattered laser light is set in the measured intersection space 34;

[0054] A 1# prism 323 for focusing is also provided between the 1# laser source 322 and the 1# cross space 34.

[0055] The 2# laser channel 421 and the 2# scattering channel 431 and the 2# air channel 41 are provided with a 2# crossing space 44.

[0056] The intersection area 45 of incident light and scattered light of the 2# laser source 422 is set in the measured intersection space 45;

[0057] A 2# prism 423 for focusing is also provided between the 2# laser source 422 and the 2# cross space 44.

[0058] The dryer 7 is also provided with an activated carbon layer 71 for removing gaseous acidic substances in the air sample.

[0059] The flow splitting device 9 is a capillary tube used to split gas; it includes 1# capillary 91 and 2# capillary 92;

[0060] The incident light of the 1# laser source 322 is parallel to the 1# laser scattering section;

[0061] The incident light of the 2# laser source 422 is perpendicular to the 2# laser scattering section;

[0062] The outlet of the PM10 collector 1 is connected to the inlet of the PM2.5 cutter 2;

[0063] The inlet of the PM2.5 cutter 2 is connected to the inlet of the 1# air channel 31;

[0064] The outlet of the 1# air channel 31 is connected to the inlet of the 2# air channel 41;

[0065] The outlet of the 2# air channel 41 is connected to the dryer 6;

[0066] The dryer is connected to the air pump 7;

[0067] The outlet of the air pump 7 is connected to the 1# capillary 81 and the 2# capillary 82;

[0068] The 1# capillary 81 is connected to the PM10 collector;

[0069] The 2# capillary 82 is connected to the outside.

[0070] Both the #1 laser intensity detector 332 and the #2 laser intensity detector 432 are connected to the signal processor 5.

[0071] See Figure 4 , The following describes the specific steps of the fine particulate matter measurement method of the present invention:

[0072] (1) Collect an air sample, collect the air sample to be measured through the PM10 collector 1, and heat and/or dilute the air sample according to the air condition, and the air flow rate is 3.3 L/min;

[0073] (2) Separate the fine particles in the air sample and separate them by the PM2.5 cutter 2. The particles with a diameter greater than 2.5 microns are removed, and the particles with a diameter less than or equal to 2.5 microns pass through the PM2.5 cutter;

[0074] (3) Measure the scattering intensity of fine particles in the air sample and convert it to the concentration of fine particles, and then pass the 1# laser scattering sensor 3 and 2# laser scattering sensor 4 to determine the scattering intensity of the fine particles in the air sample, and pass the signal processor 5 Converting the scattering intensity of the fine particles in the air sample into the concentration of the fine particles in the air sample;

[0075] (4) Dry and purify the residual gas, the residual gas after the air sample is collected by the filter 6 of fine particles, and the moisture and gaseous acidic substances in the residual gas are removed by the dryer 7 provided with an activated carbon layer 71;

[0076] (5) Recycle the residual air, stabilize the air flow through the air pump 8, and divert the purified residual gas to the PM10 collector through the 1# capillary tube 91 for diluting the air sample; the 2# capillary tube 92 passes the purified residual air to the outside.

[0077] The beneficial effect of adopting the above technical solution is: because the laser source and the laser scattering cross section of the two laser scattering sensors are parallel and vertical, they have different sensitivity to particles of different sizes. By combining the two laser scattering sensors, not only The influence of particle size on the measurement can be eliminated and the influence of particle density on the measurement can be greatly reduced; through the obtained measurement signal, the signal conversion device uses the correction coefficient to convert them into the mass concentration of PM2.5; for the repeatability of the measurement, the laser The flow rate of the scattering sensor is constant; and it is collected through a particle filter. Another important function of the filter is to check the concentration calculated by the laser scattering sensor by collecting the mass of particles for a certain period of time. By comparison, the coefficient can be corrected, which can make the measurement more accurate. Another special feature is the PM10 collector. The PM10 collector can dilute and heat the inhaled air according to different requirements, thereby minimizing air humidity. The influence of temperature on the measurement.