CN111855374A - A medium-flow atmospheric fine particle concentration device and method - Google Patents

Abstract

The invention belongs to the technical field of environmental protection, in particular to a medium-flow atmospheric fine particle concentration device and method. The device of the invention includes a collision type PM _2.5 cutting head, a water tank system, a virtual cutting system, and a condensation circulation system; the water tank system includes a water tank, an electric heating rod, and a temperature-controlled digital display device, and the PM _2.5 cutting head is communicated with the water tank; the virtual cutting system includes a virtual cutting system. Cutter, concentrated airflow vacuum pump, main airflow vacuum pump; condensate circulation system includes condensate circulation pipe and condenser; condensate circulation system is used to circulate condensate to condense and grow saturated particles; air outlet of water tank and condensate circulation system The beginning end of the condensing inner pipe is coaxially arranged, and the end of the condensing inner pipe is connected with the nozzle in the virtual cutting system. The device can concentrate the actual atmospheric fine particles by 7 to 10 times, and the concentration efficiency is high, reaching 75%-99%, and the concentration performance is stable; the device is easy to operate, reliable and stable, easy to maintain, and low cost.

Description

A medium-flow atmospheric fine particle concentration device and method

technical field

The invention belongs to the technical field of environmental protection, in particular to a device and method for concentrating particulate matter, and in particular, to a device and method for concentrating medium-flow atmospheric fine particulate matter.

technical background

PM _2.5 refers to particulate matter in the atmosphere with an aerodynamic diameter less than or equal to 2.5 microns, also known as atmospheric fine particulate matter. Although PM _2.5 is only a very small component in the composition of the earth's atmosphere, it has important effects on air quality and visibility. Atmospheric PM _2.5 has small particle size and large specific surface area, contains a large amount of toxic and harmful substances, and has a long suspension time in the atmosphere and a long transmission distance, so its negative impact on human health and atmospheric environmental quality cannot be ignored.

In recent years, China's atmospheric PM _2.5 pollution has been serious, and haze pollution often occurs, resulting in a sharp increase in the rate of medical treatment and premature death of susceptible people. In particular, the toxic and harmful chemical components carried by aerosol particles under smog endanger the health of the population and have attracted great attention from the whole society. There is substantial epidemiological evidence that PM _2.5 has both acute and chronic health effects. Exposure to high concentrations of PM _2.5 will increase the risk of acute respiratory diseases and cardiovascular and cerebrovascular diseases. At the same time, PM _2.5 may induce lung cancer, chronic obstructive pneumonia (COPD), cardiovascular and cerebrovascular diseases and other chronic diseases, affecting the human immune system, nervous system, etc. . Therefore, the research on the toxicity of haze aerosol particles has also become one of the hotspots and frontiers. However, the determination of the toxicity of atmospheric fine particles is limited by the detection technology and instruments (such as high detection limit), and it is still in the offline detection stage, and it needs to be carried out under the conditions of heavy pollution and long continuous sampling time. It cannot meet the requirements of real-time monitoring of atmospheric fine particle concentration and toxic chemical composition.

In order to fill the above technical gaps, the medium-flow atmospheric fine particulate matter concentration device developed by the present invention can concentrate and enrich the atmospheric fine particulate matter to a level sufficient to clearly detect its toxicity without changing any of its physical and chemical properties. At the same time, the device can be used in conjunction with an online toxicity detection device, making it possible to implement artificial intelligence-based online toxicity detection of atmospheric fine particles in the future, and can be widely used in environmental monitoring and health risk assessment.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a device and method for concentrating medium-flow atmospheric fine particulate matter that is reliable and stable and capable of high-efficiency concentration. The medium flow described here is 50±1 liter/min.

The structure of the medium-flow atmospheric fine particle concentration device provided by the present invention is shown in Figure 1; the device includes: a collision type PM _2.5 cutting head, a water tank heating system, a virtual cutting system, and a condensation circulation system; wherein:

The collision type PM _2.5 cutting head includes three stages of PM ₁₀ , PM ₅ and PM _2.5 , each stage is composed of an impact orifice plate and an impact separation collection plate, wherein the structure of the impact separation collection plate of the three stages is the same. The impact inertia of the particle size particles is different, and the number and diameter of holes of the three-stage impact plate are different;

The water tank heating system includes a water tank (9) for holding deionized water, and a temperature insulating layer (10) is provided on the inner wall of the water tank (9) for thermal insulation of the deionized water in the water tank (9); 9) A visual window (11) is provided on one side to observe the water surface height in the tank; the water tank (9) is provided with an electric heating rod (12) with a temperature sensor for heating deionized water; the water tank (9) A temperature control digital display device (13) is provided inside to control the temperature of deionized water; the collision type PM _2.5 cutting head (7) is communicated with the water tank (9);

The virtual cutting system includes a virtual cutter (17), a concentrated airflow vacuum pump (2), and a main airflow vacuum pump (3); wherein, the virtual cutter (17) includes a nozzle (19), a nozzle nozzle (20) ), and two gas paths: the main gas path and the concentrated gas path; the nozzle (19) and the nozzle nozzle (20) are coaxially arranged, the nozzle nozzle (20) is above the nozzle (19), and there is a certain gap between the two, and the nozzle nozzle (20) For receiving the particulate matter ejected from the nozzle (19); the concentrated airflow vacuum pump (2) communicates with the concentrated gas path on the upper part of the virtual cutter (17) through a pipeline, and a float flow meter ( 1), used to measure the flow of the pipeline; the main air flow vacuum pump (3) communicates with the main air outlet (18) on the upper part of the virtual cutter (17) through a pipeline, and the communication pipeline is provided with a drying pipe (4) and a large The flow mass flow controller (5) and the drying pipe (4) are used to dry the airflow to avoid excessive water vapor in the system from damaging the pump body, and the large flow mass flow controller (5) is used to precisely control the pipeline flow;

The condensation circulation system includes a condenser circulation pipe (6) and a condenser (8); the condenser circulation pipe (6) includes a condensation inner pipe (14), and the condensation inner pipe (14) is tightly wound with soft copper outside The spiral tube (15), the beginning and the end of the spiral tube (15) are respectively connected to the outlet and the inlet of the condenser (8); a temperature insulating layer (16) is wrapped around the spiral tube (15), so that the temperature of the condenser tube is not affected by the external temperature Influence, the condensation circulation system is used to circulate the condensate to condense and grow saturated particulate matter;

The air outlet of the water tank (9) is arranged coaxially with the beginning of the condensation inner pipe (14) in the condensation circulation system, and is connected by a quick-connect flange (including a sealing ring); the end of the condensation inner pipe (14) is connected to the nozzle ( 19) Connect.

The atmospheric fine particulate matter concentration device provided by the present invention has the following working process:

(1) Place the collision-type PM _2.5 cutting head (7) in the actual atmospheric environment, and the original atmospheric sample passes through the collision-type PM _2.5 cutting head (7) to remove the PM _2.5 aerodynamic equivalent diameter of less than or equal to 2.5 microns of atmospheric fine particles Screened out, relying on the system pumping force to enter the water tank (9);

(2) Under the visual window (11), add deionized water to two-thirds of the height of the water tank, and use an electric heating rod (12) with a temperature sensor to heat the deionized water. The digital display device (13) controls the temperature to be 45±2 degrees Celsius, so that the generated water vapor can saturate the particulate matter;

(3) The saturated particulate matter flows through the condensation inner pipe (14) of the condensation circulation system; the external circulation temperature control mode of the condenser controls the temperature at -19±1℃, so that the circulating condensate condenses the saturated particulate matter Growing up, the aerodynamic diameter of most PM _2.5 can grow to 3-4 microns;

(4) The condensed and grown PM _2.5 particles enter the virtual cutter (17) and are accelerated at the nozzle (19); the acceleration power comes from two gas paths, namely the main gas path and the concentrated gas path; in the main gas path , the main flow is precisely controlled by the large flow mass flow controller (5) to be 50±1 liters/min; in the concentrated gas path, the particles accelerated by the nozzle (19) are received by the coaxial nozzle nozzle (20) above the nozzle , control the flow rate of the concentrated gas flow to be 5 liters/min; theoretically, under the condition of the same particle concentration, the gas flow rate becomes one-tenth of the original gas flow rate, and the particle concentration in the sample becomes ten times the original concentration. , so as to achieve the concentration effect.

After the concentration is completed, the concentration factor (the ratio of the mass concentration/number concentration/chemical component concentration of PM _2.5 in the atmosphere after concentration to the mass concentration/number concentration/chemical component concentration of PM _2.5 in the atmosphere before concentration) and the concentration efficiency (the percentage of the actual concentration after concentration to the theoretical concentration concentration) for evaluation.

In this device, the condensing agent in the condenser adopts alcohol, and its concentration is adjustable, and it only needs to achieve the effect of cooling and reducing the amount of volatilization;

The condensing inner pipe (14) has a diameter of 2.5 cm and a length of 80 cm;

The control range of the flow controller (5) is 0-200 liters/min;

The diameter of the nozzle is 0.37 cm, the gap between the nozzle (9) and the nozzle nozzle (20) is 0.45 cm, and the diameter of the nozzle nozzle is 2.5 cm.

The beneficial effects of the present invention are:

(1) The device can concentrate the actual atmospheric fine particles by 7 to 10 times (the particle size is related), and the concentration efficiency is high, which can reach 75%-99% (the particle size is related), and the concentration performance is stable;

(2) The device does not have high requirements on the sampling intake air flow, and the medium flow rate of 50 liters/min can efficiently concentrate the actual atmospheric fine particles;

(3) The device is easy to operate, reliable and stable, easy to maintain, and low cost.

Description of drawings

Figure 1 is a schematic diagram of the structure of a medium-flow atmospheric fine particle concentration device. Among them, the following figure is the structure diagram of the virtual cutter.

Labels in the figure: 1 is a float flowmeter, 2 is a concentrated airflow vacuum pump, 3 is a main airflow vacuum pump, 4 is a drying pipe, 5 is a large flow mass flow controller, 6 is a condensate circulation pipe, and 7 is a collision type PM _2.5 cutting Head, 8 is the condenser, 9 is the water tank, 10 is the water tank insulation layer, 11 is the visual window, 12 is the electric heating rod with a temperature sensor, 13 is the temperature control digital display device, 14 is the condensation inner pipe, 15 16 is the thermal insulation layer, 17 is the virtual cutter, 18 is the main airflow outlet, 19 is the nozzle, and 20 is the nozzle taking over.

Detailed ways

The present invention will be further described below with reference to the accompanying drawings and embodiments.

Example 1

(1) Place the collision type PM _2.5 cutting head (7) outside the window on the 6th floor of Fudan University Environment Building. Under the action of the collision type PM _2.5 cutting head (7), the PM _2.5 aerodynamic equivalent diameter is less than or equal to 2.5 microns. Atmospheric fine particles are screened out and enter the water tank (9) by means of the suction provided by the main gas path and the concentrated gas path;

(2) Under the visual window (11), add deionized water to two-thirds of the height of the water tank, and use an electric heating rod (12) with a temperature sensor to heat the deionized water. The digital display device (13) controls the temperature to be 45±2 degrees Celsius, and the generated water vapor makes the particulate matter reach a saturated state. In the field experiment, the ambient temperature does not exceed 24 degrees Celsius. The injection of low-temperature airflow makes the supersaturated ambient temperature in the water tank (9) practical. Down to 31 degrees Celsius or lower, this parameter setting with a small difference from the actual ambient temperature can greatly reduce the loss of volatile or semi-volatile components in particulate matter;

(3) PM _2.5 particles that have reached a saturated state flow through the condensation inner pipe (14) of the condensation circulation system; the external circulation temperature control mode of the condenser controls the temperature at -19±1°C, so that the circulating condensate is effective for the saturated particulate matter. For condensation growth, the aerodynamic diameter of most PM _2.5 can be increased to 3-4 microns;

(4) The condensed and grown PM _2.5 particles enter the virtual cutter (17) and are accelerated at the nozzle (19); the acceleration power comes from two gas paths, namely the main gas path and the concentrated gas path; in the main gas path , the main flow is precisely controlled by the large flow mass flow controller (5) to be 50±1 liters/min; in the concentrated gas path, the particles accelerated by the nozzle (19) are received by the coaxial nozzle nozzle (20) above the nozzle , control the flow rate of the concentrated gas flow to be 5 liters/min; theoretically, under the condition of the same particle concentration, the gas flow rate becomes one-tenth of the original gas flow rate, and the particle concentration in the sample becomes ten times the original concentration. , so as to achieve the concentration effect.

During the enrichment process, the injection ports of the two scanning electromobility particle size spectrometers are respectively connected to the enrichment gas path of the enrichment system and the actual atmosphere, and continuously monitor the system and the actual atmosphere within each particle size range (10 to 1000). The number concentration and mass concentration of nano) particles to calculate the concentration factor (the ratio of the mass concentration/number concentration of PM _2.5 in the atmosphere after concentration to the mass concentration/number concentration of PM _2.5 in the atmosphere before concentration) and the concentration efficiency (actual concentration The percentage of the concentration after concentration in the theoretical concentration concentration), the detailed data are shown in Table 1. The flow rate of the two scanning electric mobility particle size spectrometers is set to 0.3 liters/min. Therefore, when connected to the enrichment system, the air flow of 0.3 liters/min in the concentrated gas path enters the scanning electric mobility particle size spectrometer. The remaining 4.7 L/min of airflow can be used for subsequent particulate sampling or real-time monitoring. In addition, because the water vapor in the system is too large, it is not easy to directly enter the scanning electric mobility particle size spectrometer. It is necessary to add a drying tube in the front section to remove the water vapor and reduce the particle size.

Table 1 Enrichment efficiency of different particle sizes in real atmospheric environment

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Claims (6)

1. A medium-flow atmospheric fine particle concentration device, characterized in that, comprising: a collision type PM _2.5 cutting head (7), a water tank heating system, a virtual cutting system, and a condensation circulation system; wherein: The collision type PM _2.5 cutting head includes three stages of PM ₁₀ , PM ₅ and PM _2.5 , each stage is composed of an impact orifice plate and an impact separation collection plate, wherein the structure of the impact separation collection plate of the three stages is the same. The impact inertia of the particle size particles is different, and the number and diameter of holes of the three-stage impact plate are different; The water tank heating system includes a water tank (9) for holding deionized water, and a temperature insulating layer (10) is provided on the inner wall of the water tank (9) for thermal insulation of the deionized water in the water tank (9); 9) A visual window (11) is provided on one side to observe the water surface height in the tank; the water tank (9) is provided with an electric heating rod (12) with a temperature sensor for heating deionized water; the water tank (9) A temperature control digital display device (13) is provided inside to control the temperature of deionized water; the PM _2.5 cutting head (7) is communicated with the water tank (9); The virtual cutting system includes a virtual cutter (17), a concentrated airflow vacuum pump (2), and a main airflow vacuum pump (3); wherein, the virtual cutter (17) includes a nozzle (19), a nozzle nozzle (20) ), and two gas paths: the main gas path and the concentrated gas path; the nozzle (19) and the nozzle nozzle (20) are coaxially arranged, the nozzle nozzle (20) is above the nozzle (19), and there is a certain gap between the two, and the nozzle nozzle (20) For receiving the particulate matter ejected from the nozzle (19); the concentrated airflow vacuum pump (2) communicates with the concentrated gas path on the upper part of the virtual cutter (17) through a pipeline, and a float flow meter ( 1), used to measure the flow of the pipeline; the main air flow vacuum pump (3) communicates with the main air outlet (18) on the upper part of the virtual cutter (17) through a pipeline, and the communication pipeline is provided with a drying pipe (4) and a large The flow mass flow controller (5) and the drying pipe (4) are used to dry the airflow to avoid excessive water vapor in the system from damaging the pump body, and the large flow mass flow controller (5) is used to precisely control the pipeline flow; The condensation circulation system includes a condenser circulation pipe (6) and a condenser (8); the condenser circulation pipe (6) includes a condensation inner pipe (14), and the condensation inner pipe (14) is tightly wound with soft copper outside The spiral tube (15), the beginning and the end of the spiral tube (15) are respectively connected to the outlet and the inlet of the condenser (8); a temperature insulating layer (16) is wrapped around the spiral tube (15), so that the temperature of the condenser tube is not affected by the external temperature Influence, the condensation circulation system is used to circulate the condensate to condense and grow saturated particulate matter; The air outlet of the water tank (9) is arranged coaxially with the beginning of the condensation inner pipe (14) in the condensation circulation system, and is connected by a quick-connect flange (including a sealing ring); the end of the condensation inner pipe (14) is connected to the nozzle ( 19) Connect. 2 . The medium-flow atmospheric fine particle concentration device according to claim 1 , wherein the condensing agent in the condenser adopts alcohol, and its concentration can be adjusted to achieve the effects of refrigeration and reducing volatilization. 3 . 3 . The medium flow rate atmospheric fine particle concentration device according to claim 1 , wherein the inner condensing pipe ( 14 ) has a diameter of 2.5 cm and a length of 80 cm. 4 . 4. The medium-flow atmospheric fine particle concentration device according to claim 1, characterized in that the diameter of the nozzle is 0.37 cm, the gap between the nozzle (9) and the nozzle nozzle (20) is 0.45 cm, and the diameter of the nozzle nozzle is 2.5 cm . 5. A method for concentrating medium-flow atmospheric fine particulate matter based on the device of claim 1, 2 or 3, wherein the specific steps are: (1) The PM _2.5 cutting head (7) is placed in the actual atmospheric environment, and the original atmospheric sample passes through the PM _2.5 cutting head (7) to screen out the atmospheric fine particles whose PM _2.5 aerodynamic equivalent diameter is less than or equal to 2.5 microns. The system is pumped into the water tank (9); (2) Under the visual window (11), add deionized water to two-thirds of the height of the water tank, and use an electric heating rod (12) with a temperature sensor to heat the deionized water. The digital display device (13) controls the temperature to be 45±2 degrees Celsius, so that the generated water vapor can saturate the particulate matter; (3) The saturated particulate matter flows through the condensation inner pipe (14) of the condensation circulation system; the external circulation temperature control mode of the condenser controls the temperature at -19±1℃, so that the circulating condensate condenses the saturated particulate matter Growing up, the aerodynamic diameter of most PM _2.5 can grow to 3-4 microns; (4) The condensed and grown PM _2.5 particles enter the virtual cutter (17) and are accelerated at the nozzle (19); the acceleration power comes from two gas paths, namely the main gas path and the concentrated gas path; in the main gas path , the main flow is precisely controlled by the large flow mass flow controller (5) to be 50±1 liters/min; in the concentrated gas path, the particles accelerated by the nozzle (19) are received by the coaxial nozzle nozzle (20) above the nozzle , control the flow rate of the concentrated gas flow to be 5 liters/min; theoretically, under the condition of the same particle concentration, the gas flow rate becomes one-tenth of the original gas flow rate, and the particle concentration in the sample becomes ten times the original concentration. , so as to achieve the concentration effect. 6. The medium-flow atmospheric fine particle concentration method according to claim 5, characterized in that, after the concentration is completed, the concentration factor and concentration efficiency are finally evaluated; wherein, the concentration factor refers to: the mass of PM _2.5 in the atmosphere after concentration The ratio of concentration/number concentration/chemical component concentration to the mass concentration/number concentration/chemical component concentration of PM _2.5 in the atmosphere before concentration; concentration efficiency refers to the percentage of the actual concentration after concentration to the theoretical concentration concentration.

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