CN115372220A - Particulate matter concentration detection device - Google Patents
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- 239000013618 particulate matter Substances 0.000 title claims abstract description 145
- 238000001514 detection method Methods 0.000 title claims abstract description 70
- 238000005070 sampling Methods 0.000 claims abstract description 163
- 230000005250 beta ray Effects 0.000 claims abstract description 86
- 238000010521 absorption reaction Methods 0.000 claims abstract description 42
- 238000012545 processing Methods 0.000 claims abstract description 41
- 238000000034 method Methods 0.000 claims abstract description 23
- 239000000428 dust Substances 0.000 claims description 35
- 239000002245 particle Substances 0.000 claims description 20
- 239000000126 substance Substances 0.000 claims description 12
- 238000005086 pumping Methods 0.000 claims description 3
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- 238000004364 calculation method Methods 0.000 description 5
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- 230000000149 penetrating effect Effects 0.000 description 4
- 230000002745 absorbent Effects 0.000 description 3
- 239000002250 absorbent Substances 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 230000005255 beta decay Effects 0.000 description 2
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- 230000001419 dependent effect Effects 0.000 description 1
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Abstract
The application provides a particulate matter concentration detection device, includes: the device comprises a sampling chamber, a filter paper mounting part, an air pump, an air flow detection device, a beta ray generator, a detector and a data processing part, wherein the data processing part receives beta ray intensity values detected by the detector in each sampling period, the detector takes a first time interval as the sampling period, and the equivalent particulate matter concentration of each sampling period is calculated based on a beta ray absorption method; the data processing part is provided with a sample space, the sample space is used for sequentially storing the equivalent particulate matter concentration of each sampling period according to the sampling time axis sequence, and the capacity of the sample space is N; the data processing part accumulates the equivalent particulate matter concentration of each sampling period in the sample space to obtain the real-time particulate matter concentration. The device that this application provided has realized the real-time supervision to particulate matter concentration.
Description
Technical Field
The application relates to the technical field of air quality monitoring equipment, in particular to a particulate matter concentration detection device.
Background
At present, the mainstream monitoring method for air station environment monitoring in China is a beta ray absorption method, which utilizes beta particles released when C14 atomic nuclei undergo beta decay, wherein the beta particles are actually high-speed electron current and have strong penetrating power, and when the beta particles penetrate through an absorbing substance with a certain thickness, the strength of the beta particles is gradually weakened along with the increase of the thickness of the absorbing layer.
In the prior art, the instrument utilizes an air suction pump to be matched with a flow regulating valve and a gas quality sensor for stable sampling, particulate matters in the atmosphere are absorbed on filter paper between a radioactive source and a detector after being cut by a cutter, and the change of the count value of the detector before and after air suction reflects the change of the mass of dust spots absorbed on the filter paper, so that the concentration of the particulate matters in the sampled air can be obtained.
When the detector detects the quantity of the beta particles, the detector can fluctuate, and the absorption intensity of the beta particles obviously changes to reach a certain air extraction volume (the sampling time is more than or equal to 30 min), so that the beta ray absorption measurement method cannot detect the concentration of the particulate matters in real time, the real-time change condition of the content of the air particulate matters cannot be reflected, the concentration value received by the platform is an hourly mean value, and the position of the pollution source cannot be timely fed back and accurately positioned when sudden high-concentration alarm occurs.
Therefore, there is a need to provide a technical solution to solve the problem existing in the prior art that the content of air particles cannot be reflected in real time and the pollution source cannot be accurately located.
Disclosure of Invention
The application aims to solve the problem that the content of particulate matters cannot be reflected in real time and a pollution source cannot be accurately positioned in the prior art.
Based on the above-mentioned purpose, this application provides a particulate matter concentration detection device, includes:
a sampling chamber comprising a gas inlet and a gas outlet;
the filter paper mounting part is arranged in the sampling chamber and is used for mounting filter paper;
the air pump is connected with the sampling chamber and used for pumping gas to be detected, the gas to be detected enters the sampling chamber from the air inlet and is discharged from the air outlet after passing through the filter paper, and particulate matters in the gas to be detected are enriched on the filter paper to form dust spots;
gas flow detection means for detecting the volume of gas flowing through the sampling chamber per unit time;
a beta ray generator for emitting beta rays to the location of the dust spot;
the detector is used for receiving the beta rays passing through the dust spot and detecting the intensity value of the beta rays after passing through the dust spot;
characterized in that the device also comprises a data processing part,
the data processing part receives beta ray intensity values detected by the detector in each sampling period, the detector takes a first time interval as a sampling period, and the equivalent particulate matter concentration of each sampling period is calculated based on a beta ray absorption method;
the data processing part is provided with a sample space, the sample space is used for sequentially storing the equivalent particulate matter concentration of each sampling period according to the sampling time axis sequence, and the capacity of the sample space is N;
and the data processing part accumulates the equivalent particulate matter concentration of each sampling period in the sample space to obtain the real-time particulate matter concentration.
Further, when the sampling frequency of the detector is greater than the capacity of the sample space, the sample space is updated, the equivalent particulate matter concentration entering the sample space at the first time is removed according to the sequence of a sampling time axis, the equivalent particulate matter concentration of the latest sampling period is stored in the sample space, and the updated equivalent particulate matter concentrations of all sampling periods in the sample space are accumulated by the data processing part to obtain the real-time particulate matter concentration.
Further, the equivalent particulate matter concentration for each sampling period is expressed as follows:
wherein the content of the first and second substances,I 1 representing the intensity value of the beta-ray for the last sampling period,I 2 the intensity value of the beta-ray representing the current sampling period,μ m which represents the absorption coefficient of mass,Vand the total volume of gas to be pumped by the gas pump in preset N sampling periods is represented, N represents the space capacity of the sample, and c represents the equivalent particulate matter concentration in the current sampling period.
Further, when the gas flow detection device detects that gas flow in the sampling chamber is lower than a first flow preset threshold value, or when the detection duration of the detector is equal to a first time preset threshold value, the filter paper mounting part is replaced by the filter paper, and the detector resets the sampling times.
Further, when the real-time particulate matter concentration calculated by the data processing part is lower than a first concentration preset threshold value, the filter paper is replaced by the filter paper mounting part, and the sampling frequency is reset by the detector.
Further, the data processing part is provided with a second time preset threshold, and when the sampling duration of the detector is greater than or equal to the second time preset threshold, the data processing part calculates the equivalent particulate matter concentration of the current sampling period and stores the equivalent particulate matter concentration of the current sampling period into the sample space according to the sampling time axis sequence.
Further, the device also comprises a temperature detection module for detecting the temperature in the sampling chamber in real time;
the data processing part calculates and obtains a beta ray intensity value after temperature compensation through a temperature compensation algorithm according to the temperature in the sampling chamber and the beta ray intensity value of the current sampling period detected by the detector;
and the data processing part calculates the equivalent particulate matter concentration of the current sampling period by a beta ray absorption method according to the beta ray intensity value after temperature compensation.
Further, the temperature compensation algorithm is represented as follows:
S T =S-a（T-T 0 ）
wherein S is T Represents the beta ray intensity value after temperature compensation, S represents the beta ray intensity value without temperature compensation,arepresents the slope of the beta ray intensity value with the temperature change, T represents the temperature value in the sampling chamber, T 0 Indicating the standard temperature value set by the system.
Further, the slope of the beta ray intensity value along with the change of the temperatureaThe following conditions are satisfied:
wherein the content of the first and second substances,y i represents the temperature compensated beta-ray intensity values,x i which represents a value of the temperature inside the sampling chamber 11,xto representx i The amount of change in the amount of change,arepresents the slope of the beta ray intensity value with temperature change, and b represents a constant.
The application also provides a particulate matter concentration detection method, which comprises the following steps:
extracting gas to be detected to enable particles in the gas to be detected to be enriched on filter paper to form dust spots;
detecting the beta ray intensity value after the beta ray passes through the dust spot in each sampling period;
calculating the equivalent particulate matter concentration in each sampling period based on a beta ray absorption method according to the beta ray intensity value of each sampling period;
setting a sample space, wherein the sample space is used for sequentially storing the equivalent particulate matter concentration of each sampling period according to a sampling time axis sequence, and the capacity of the sample space is N;
and accumulating the equivalent particulate matter concentration of each sampling period in the sample space to obtain the real-time particulate matter concentration.
The embodiment of the application provides a particulate matter concentration detection device, can realize detecting the real-time situation of change of air particulate matter content, in time report to the police and feed back and pinpoint the pollution source position.
Drawings
Fig. 1 is a schematic view of a particulate matter concentration detection apparatus provided herein;
fig. 2 is a schematic diagram of a reaction mechanism of a detection platform in the particulate matter concentration detection apparatus provided herein;
fig. 3 is a schematic diagram illustrating changes in the concentration of particulate matter detected by the particulate matter concentration detection apparatus provided in the present application;
FIG. 4 is a schematic diagram showing the variation of the actual concentration of particulate matter in the gas to be measured;
fig. 5 is a flowchart illustrating the operation of the particulate matter concentration detection apparatus provided herein.
Detailed Description
The present invention will be described in detail with reference to the specific embodiments shown in the drawings, but the embodiments are not limited to the present invention, and structural, methodological, or functional changes made by those skilled in the art according to the embodiments are included in the scope of the present invention.
As shown in fig. 1, the particulate matter concentration detection device provided by the present invention includes a sampling chamber 11, a filter paper mounting portion 12, an air pump 13, an air flow rate detection device 14, a β -ray generator 15, a detector 16, and a data processing portion 17.
Wherein, the first and the second end of the pipe are connected with each other,
a sampling chamber 11 comprising an air inlet and an air outlet;
a filter paper mounting part 12 provided in the sampling chamber 11 for mounting filter paper;
the air pump 13 is connected with the sampling chamber 11 and used for pumping gas to be detected, the gas to be detected enters the sampling chamber 11 from the air inlet and is discharged from the air outlet after passing through the filter paper, and particulate matters in the gas to be detected are enriched on the filter paper to form dust spots;
a gas flow rate detection means 14 for detecting the volume of gas flowing through the sampling chamber 11 per unit time;
a beta ray generator 15 for emitting beta rays to the position of the dust spot;
the detector 16 is used for receiving the beta rays passing through the dust spots and detecting the intensity values of the beta rays after passing through the dust spots;
and the data processing part 17 is used for receiving the beta ray intensity value detected by the detector 16, the detector 16 takes a first time interval as a sampling period, and the data processing part 17 calculates the equivalent particulate matter concentration in each sampling period based on a beta ray absorption method.
As an alternative implementation, the air pump 13 may be arranged at the outlet of the sampling chamber 11.
As an alternative implementation, the gas flow detection means 14 may be provided within the sampling chamber 11.
As an alternative implementation, the beta ray generator 15 can be arranged in the sampling chamber 11, and the beta ray emitted by the beta ray generator 15 can irradiate the position on the filter paper where the dust spot is generated.
The detector 16 may be disposed on both sides of the filter paper opposite to the beta-ray generator 15. The detector 16 is used for receiving the beta ray passing through the dust spot and detecting the intensity value of the beta ray after passing through the dust spot.
As an optional implementation manner, the particulate matter concentration detection apparatus provided by the present application detects the particulate matter concentration based on a β -ray absorption method.
In the conventional beta-ray absorption method, the principle is that beta particles are released when C14 atomic nuclei undergo beta decay, the beta particles are actually high-speed electron current, the penetrating power of the beta particles is strong, and when the beta particles penetrate through a certain thickness of absorption substance, the strength of the beta particles is gradually weakened along with the increase of the thickness of the absorption layer. When the thickness of the absorbing substance is much smaller than the range of the beta particles, the absorption of beta rays in the substance can be approximated as:
wherein the content of the first and second substances,I 0 is the strength in the absence of an absorbing substance,Ithe beta ray penetrates through the filter paper to a thickness oftThe strength after absorption of the substance(s),μm=μ/ρcalled the mass absorption coefficient or mass attenuation coefficient, in units ofcm²/g；tm=tρReferred to as mass thickness, ing/cm²；ρIs the density of the absorbent material ing/cm³. For the different absorbent materials it is possible to use,μmincreasing slowly with increasing atomic number. For the same absorbent material(s) it is,μmrelated to the radiation energy.
As an alternative implementation, the detector 16 records the intensity of the beta rays passing through a blank filter paperI 1 Derived from formula (1):
as an optional implementation manner, a certain volume of the gas to be detected is pumped by the air pump 13, so that the particulate matters in the gas to be detected are enriched on the filter paper to form dust spots.
The detector 16 detects the intensity value of the beta ray after the beta ray passes through the dust spot, and the intensity value of the beta ray after the beta ray passes through the dust spot is set asI 2 Obtained by the formula (1):
in the formula: delta m is the mass thickness of particulate matter, and the unit is g/cm had been had.
Let I 0 And remains unchanged throughout the measurement. Combining equations (2) and (3) to obtain:
since the area of the filter paper to be detected and the evacuation volume are known, wherein the evacuation volume = sampling flow rate × sampling time, the concentration of particulate matter c =Δm/V (in mg/m) can be calculated.
According to the above description, when the traditional beta-ray absorption method is used for detecting the concentration of the particulate matter, the absorption intensity of the beta particles is obviously changed, and a certain air extraction volume needs to be reached, so that the traditional beta-ray absorption method cannot detect the concentration of the particulate matter in real time, and cannot reflect the real-time change of the content of the particulate matter in the air. To this, the particulate matter concentration detection device that this application provided improves on traditional beta ray absorption method basis for the particulate matter concentration detection device that this application provided can reflect the real-time change of particulate matter concentration.
As an optional implementation manner, in order to realize real-time measurement of the particulate matter concentration, in the particulate matter concentration detection apparatus provided in the embodiment of the present application, the data processing unit 17 performs the following processing:
the data processing part 17 receives the beta ray intensity value detected by the detector 16, the detector 16 takes a first time interval as a sampling period, and the data processing part 17 calculates the equivalent particulate matter concentration in each sampling period based on the beta ray absorption method.
The data processing section 17 may be provided with a sample space for sequentially storing the equivalent particulate matter concentration for each sampling period in accordance with a sampling time axis. The capacity of sample space is N, and the equivalent particulate matter concentration that N sampling cycle corresponds can be deposited in sample space promptly.
The data processing unit 17 accumulates the equivalent particulate matter concentrations of the respective sampling periods in the sample space to obtain the real-time particulate matter concentration.
As an alternative implementation manner, when the sampling number of times of the detector 16 is less than or equal to the sample space capacity, the data processing portion 17 accumulates the equivalent particulate matter concentrations of each sampling period in the sample space to obtain the real-time particulate matter concentration.
As an optional implementation manner, when the sampling frequency of the detector 16 is greater than the capacity of the sample space, the sample space is updated, the equivalent particulate matter concentration that enters the sample space at the earliest time is removed according to the sampling time axis sequence, and the equivalent particulate matter concentration of the latest sampling period is stored in the sample space, and the data processing unit 17 accumulates the equivalent particulate matter concentrations of the updated sample space in each sampling period to obtain the real-time particulate matter concentration.
According to the above description, the present application can realize real-time monitoring of particulate matter concentration based on the "beta ray absorption method" by designing the sample space.
As an alternative implementation, the equivalent particulate matter concentration for each sampling period is expressed as follows:
wherein the content of the first and second substances,I 1 representing the intensity value of the beta-ray for the last sampling period,I 2 the intensity value of the beta-ray representing the current sampling period,μ m which represents the absorption coefficient of mass,Vthe total volume of gas to be pumped by the gas pump 13 in preset N sampling periods is represented, N represents the sample space capacity, and c represents the equivalent particulate matter concentration in the current sampling period.
As an alternative implementation, when the gas flow detecting device 14 detects that the gas flow in the sampling chamber 11 is lower than the first flow preset threshold, the filter paper mounting part 12 replaces the filter paper, and the detector 16 resets the sampling times. When the gas flow is lower than the preset threshold value of the first flow, the gas flow is too low, so that the gas weighing error in the detection occurs, the filter paper is replaced, the sampling frequency is reset, and the detection precision of the particulate matter concentration detection device is ensured.
As an optional implementation manner, when the detection duration of the detector 16 is equal to the first time preset threshold, considering that the dust spots on the filter paper are accumulated too much to affect the measurement accuracy, the filter paper can be replaced by the filter paper mounting portion 12, and the detector 16 resets the sampling times to ensure the detection accuracy of the particulate matter concentration detection device.
As an alternative implementation manner, when the real-time particulate matter concentration calculated by the data processing unit 17 is lower than the first concentration preset threshold, the filter paper is replaced by the filter paper mounting unit 12, and the detector 16 resets the sampling times, so as to ensure the detection accuracy of the particulate matter concentration detection device.
As an optional implementation manner, the data processing portion is provided with a second time preset threshold, and when the sampling duration of the detector 16 is greater than or equal to the second time preset threshold, the data processing portion calculates the equivalent particulate matter concentration of the current sampling period, and stores the equivalent particulate matter concentration in the sample space according to the sampling time axis sequence. The purpose of setting the second time preset threshold is to facilitate the detection of the real-time concentration of the particulate matter in the detection environment after the particulate matter concentration detection device operates for a certain period of time.
The particulate matter concentration detection device provided by the invention further comprises a temperature detection module, and the temperature detection module is used for detecting the temperature in the sampling chamber 11 in real time.
As an alternative implementation manner, the data processing unit obtains the temperature-compensated β -ray intensity value by calculating through a temperature compensation algorithm according to the temperature in the sampling chamber 11 and the β -ray intensity value of the current sampling period detected by the detector 16. The data processing portion calculates the equivalent particulate matter concentration of current sampling period through the beta ray absorption method according to the beta ray intensity value after the temperature compensation to can reduce the influence that the gas temperature that awaits measuring detected beta ray intensity value, make the real-time particulate matter concentration that particulate matter concentration detection device that this application provided calculated more accurate.
As an alternative implementation, the indoor temperature value of the sampling chamber 11 may be set as an independent variablex i The temperature compensated beta ray intensity value can be set as a dependent variabley i N data (n) between variables can be obtainedx 1 ，y 1 ）、（x 2 ，y 2 ）、……（x i ，y i ). Within the xoy plane, n points can be obtainedp i （x i ，y i ) (n =0,1,2,3, \8230;, n) are scattered points, which are all on a straight line. The expression for this line can be expressed as:
y=ax+b（6）
in the formula (I), the compound is shown in the specification,arepresents the slope of the beta ray intensity value with temperature change, and b represents a constant.
And obtaining a deviation square sum formula of each data and the linear curve by using a least square method:
as an optional implementation mode, the slope of the change of the beta ray intensity value along with the temperature in the particulate matter concentration detection deviceaThe following conditions are satisfied:
wherein, the first and the second end of the pipe are connected with each other,y i representing the temperature compensated beta-ray intensity values,x i which represents a value of the temperature inside the sampling chamber 11,xrepresentx i The amount of change in the amount of change,arepresents the slope of the beta-ray intensity value with temperature, and b represents a constant.
And a and b can be solved according to each data and formula on the scatter diagram, and a straight line fitting equation can be obtained.
Therefore, the temperature compensation algorithm of the particulate matter concentration detection device can be expressed as follows:
S T =S-a（T-T 0 ）（10）
wherein S is T Represents the beta ray intensity value after temperature compensation, S represents the beta ray intensity value without temperature compensation,arepresents the slope of the beta ray intensity value as a function of temperature, T represents the temperature value in the sampling chamber 11, T 0 Indicating the standard temperature value set by the system.
As shown in fig. 2, the particulate matter concentration detection apparatus provided by the present invention further includes: the device comprises a wind direction detection module 21, a camera module 22 and a communication module 23.
The wind direction detection module 21 is disposed on the surface of the particulate matter concentration detection device and used for detecting the wind direction of the environment where the particulate matter concentration detection device is located.
The camera module 22 is used for capturing images in a certain area in front of the camera module 22.
The communication module 23 is in communication connection with the monitoring platform, and is used for sending the image acquired by the camera module 22 to the monitoring platform.
As an alternative implementation, the wind direction detection module 21 may be a wind direction sensor.
As an alternative implementation, the camera module 22 may be ccd or cmos.
As an alternative implementation, the communication module 23 may be a wireless communication module.
As an optional implementation manner, when the real-time particulate matter concentration value calculated by the data processing portion is higher than the second concentration preset threshold, the wind direction detection module 21 detects the wind direction at this time, the camera module 22 captures an area image of the windward direction, and sends the area image of the windward direction to the monitoring platform through the communication module 23. The monitoring platform can determine the direction of the pollution source and inform operation and maintenance personnel of reaching the accurate direction of the pollution source to deal with the problem in time.
The embodiment of the application also provides a particulate matter concentration detection method, which comprises the following steps:
extracting gas to be detected to enable particles in the gas to be detected to be enriched on filter paper to form dust spots;
detecting the beta ray intensity value after the beta ray passes through the dust spot in each sampling period;
calculating the equivalent particulate matter concentration in each sampling period based on a beta ray absorption method according to the beta ray intensity value of each sampling period;
setting a sample space, wherein the sample space is used for sequentially storing the equivalent particulate matter concentration of each sampling period according to a sampling time axis sequence, and the capacity of the sample space is N;
and accumulating the equivalent particulate matter concentration of each sampling period in the sample space to obtain the real-time particulate matter concentration.
And when the sampling times are less than or equal to the volume of the sample space, accumulating the equivalent particulate matter concentration of each sampling period in the sample space to obtain the real-time particulate matter concentration.
And when the sampling times are greater than the capacity of the sample space, updating the sample space, removing the equivalent particulate matter concentration which enters the sample space firstly according to the sequence of the sampling time axis, storing the equivalent particulate matter concentration of the latest sampling period into the sample space, and accumulating the equivalent particulate matter concentrations of all the sampling periods in the updated sample space to obtain the real-time particulate matter concentration.
As an alternative implementation manner, in the embodiment of the present application, the sampling period may be set to 1 second, and the capacity N of the sample space may be 3600.
And when the sampling times of the detector are less than or equal to the volume of the sample space, namely the sampling times are less than 3600, accumulating the equivalent particulate matter concentration of each sampling period in the sample space to obtain the real-time particulate matter concentration.
When the sampling frequency of the detector is greater than the capacity of the sample space, namely the sampling frequency is greater than 3600, the sample space is updated, the equivalent particulate matter concentration entering the sample space firstly is removed according to the sequence of a sampling time axis, the equivalent particulate matter concentration of the latest sampling period is stored in the sample space, and the equivalent particulate matter concentrations of all the sampling periods in the updated sample space are accumulated to obtain the real-time particulate matter concentration.
As shown in fig. 3, it shows a schematic diagram of the change in the concentration of particulate matter detected by the particulate matter concentration detection device provided by the present application.
As an optional implementation manner, in the embodiment of the present application, a sampling period may be set to be 1 second, a first time preset threshold is 8 hours, a second time preset threshold is 5 minutes, and a sample volume N is 3600. Namely, sampling is carried out once per second, the real-time particulate matter concentration is calculated when the sampling time length is longer than 5 minutes, the data volume with the sampling time length of 1 hour is stored in the sample space at most, and the filter paper is replaced after the device continuously monitors for 8 hours.
The following is a detailed description of the concentration calculation method:
setting the intensity value of the beta ray before penetrating through the dust spot as a blank absorption intensity value, and setting the intensity value after penetrating through the dust spot as a dust spot absorption intensity value:
(1) Blank absorption intensity value: i is 0 ；
Dust spot absorption strength value: i is 1 ；
C1 is obtained according to concentration calculation formulas (1), (2), (3) and (4), and the concentration value displayed on the instrument measurement interface =
。
(2) Blank absorption intensity value: i is 1 ；
Dust spot absorption strength value: I.C. A 2 ；
Then C2 is obtained according to the concentration calculation formulas (1), (2), (3) and (4), and the concentration value displayed on the instrument measurement interface is =
。
Each of the following values is analogized, 3600 seconds corresponds to 1 hour,
(3600) Blank absorption intensity value: i is 3599 ；
Dust spot absorption strength value: i is 3600 ；
C3600 is obtained according to the concentration calculation formulas (1), (2), (3) and (4), and the concentration value displayed on the instrument measurement interface is =
(the concentration is added up to one hour).
When the sampling duration is equal to 1 hour, the sample space storage data reaches the upper limit of the capacity, at the moment, the equivalent particulate matter concentration which firstly enters the sample space is removed according to the time shaft sequence, and the equivalent particulate matter concentration of the latest sampling period is stored. That is, when the concentration value is added to the 3600 th one, the concentration value displayed on the measurement interface needs to be removed from the C1 concentration value, and the C3601 concentration value is added (mainly to display the real-time concentration value of one hour), and the average flow of the calculated volume is calculated from 2 seconds to 3601 seconds, as shown in the following example:
(3601) Blank absorption intensity value: i is 3600 ；
Strong absorption of dust spotValue of: I.C. A 3601 ；
The following formula (1), (2), (3) and (4) are calculated according to the concentration: concentration value displayed on measurement interface of C3601 instrument =
。
This procedure was followed until the filter paper was replaced.
And after the filter paper is replaced, the air pump pumps air, and the concentration calculation is started after the accumulated sampling time of the detector is more than or equal to the second time preset threshold value for 5 minutes.
After the filter paper is replaced, the data stored in the sample space can still be updated in the time axis order. For example, the concentration value C25200 at 25200 (i.e. 7 hours) in the sample space may be removed and the concentration value C28801 (i.e. 8 hours 1 second) added in the sample space.
In a similar way, after changing filter paper and detector accumulation sampling duration is more than or equal to 5 minutes, the device that this application provided can carry out real-time supervision to particulate matter concentration. That is, in the sample space, C25500 (i.e., the concentration at 7 hours and 5 minutes) is removed in the time axis order, and C9101 (i.e., the concentration at 8 hours and 5 minutes) is added, so that the real-time particulate matter concentration at 8 hours and 5 minutes can be calculated.
The following examples:
(28801) Blank absorption intensity value: I.C. A 28800 ；
Dust spot absorption strength value: i is 28801 ；
The following formula (1), (2), (3) and (4) are calculated according to the concentration: c28801, concentration value displayed on instrument measurement interface =
。
(n) blank absorption intensity value: I.C. A n-1 ；
Dust spot absorption strength value: i is n ；
The following formula (1), (2), (3) and (4) are calculated according to the concentration: cn, concentration value displayed on instrument measurement interface =
。
The method is carried out according to the method, until the instrument is powered off or the instrument gives an alarm due to fault, the original state is returned, and the concentration value is accumulated again.
As shown in fig. 4, fig. 4 is a schematic diagram of the actual concentration change of particulate matter in the gas to be measured. With reference to fig. 3 and 4, the particulate matter concentration detection apparatus provided by the present invention can realize real-time concentration detection.
As shown in fig. 5, the work flow of the particulate matter concentration detection apparatus provided by the present invention includes:
replacing filter paper, resetting the sampling times by the detector, and starting the device to operate;
the air pump starts to pump air, the signals of the detector are received in real time, and the signals are received every second;
detecting the temperature T of a beta probe 0 Can be set to T 0 =25 ℃. If the temperature of the detector is not equal to 25 ℃, temperature compensation is carried out: s T =S-a（T-T 0 ）。
Setting the sampling time to reach a set value for 5 minutes, and starting to calculate the concentration;
the particulate matter concentration detection device can set a second concentration preset threshold, and when the particulate matter concentration detection device detects that the real-time particulate matter concentration value is higher than the second concentration preset threshold, a platform high concentration alarm mechanism is triggered: 1. high concentration of marker particles; 2. recording the wind direction of the instantaneous change of the concentration; 3. the camera rotates to the recorded wind direction position to perform real-time monitoring; 4. sending high-concentration early warning to operation and maintenance personnel;
it should be determined whether one of the following conditions is satisfied: 1. the first flow preset threshold value is less than or equal to 15.85L/min; 2. the first time preset threshold value is 8 hours; 3. and (3) carrying out a dry milling on the first particulate matter concentration or the second particulate matter concentration, wherein the dry milling is carried out at a speed of 1500 mu g/m. If one of the conditions is met, returning to execute the command of moving the instrument pressing block upwards; and if the conditions are not met, returning to the instruction that the sampling execution time reaches the set value for 5 minutes and starting to calculate the concentration.
The real-time concentration is transmitted to the environment monitoring platform through the concentration algorithm, and the pollution source is accurately positioned by combining a high-concentration alarm mechanism of the environment monitoring platform; the instrument monitors that the content of air particles suddenly changes, and transmits the air particles to an environment monitoring platform in real time to trigger a high-concentration alarm mechanism: 1. marking a high concentration value of the particulate; 2. recording the wind direction of the instantaneous concentration mutation; 3. the camera rotates to the recorded wind direction position to perform real-time monitoring; 4. sending a high-concentration alarm to operation and maintenance personnel; and when the operation maintenance personnel arrive at the site, the direction of the pollution source can be accurately determined, and the problem can be timely solved.
In conclusion, the particulate matter concentration detection device provided by the invention can detect the change of the particulate matter concentration in the environment, accurately position the pollution source and timely solve the problem.
While the invention has been described with reference to certain preferred embodiments, it will be understood by those skilled in the art that the following descriptions are provided for illustration and example only and not for the purpose of limiting the invention as defined by the appended claims: rather, the invention is to cover all modifications, alternatives, combinations and simplifications which may be included within the spirit and scope of the invention as defined by the appended claims.
Claims (10)
1. A device for detecting the concentration of particulate matter,
a sampling chamber comprising a gas inlet and a gas outlet;
the filter paper mounting part is arranged in the sampling chamber and is used for mounting filter paper;
the air pump is connected with the sampling chamber and used for pumping gas to be detected, the gas to be detected enters the sampling chamber from the air inlet and is discharged from the air outlet after passing through the filter paper, and particulate matters in the gas to be detected are enriched on the filter paper to form dust spots;
gas flow detection means for detecting the volume of gas flowing through the sampling chamber per unit time;
a beta ray generator for emitting beta rays to the location of the dust spot;
the detector is used for receiving the beta rays passing through the dust spot and detecting the intensity value of the beta rays after passing through the dust spot;
characterized in that the device also comprises a data processing part,
the data processing part receives beta ray intensity values detected by the detector in each sampling period, the detector takes a first time interval as a sampling period, and the equivalent particulate matter concentration of each sampling period is calculated based on a beta ray absorption method;
the data processing part is provided with a sample space, the sample space is used for sequentially storing the equivalent particulate matter concentration of each sampling period according to the sampling time axis sequence, and the capacity of the sample space is N;
and the data processing part accumulates the equivalent particulate matter concentration of each sampling period in the sample space to obtain the real-time particulate matter concentration.
2. The particulate matter concentration detection apparatus according to claim 1,
when the sampling times of the detector are larger than the capacity of the sample space, the sample space is updated, the equivalent particulate matter concentration entering the sample space firstly is removed according to the sequence of a sampling time axis, the equivalent particulate matter concentration of the latest sampling period is stored in the sample space, and the updated equivalent particulate matter concentration of each sampling period in the sample space is accumulated by the data processing part to obtain the real-time particulate matter concentration.
3. The particulate matter concentration detection apparatus according to claim 1, wherein the equivalent particulate matter concentration for each sampling period is expressed as follows:
wherein the content of the first and second substances,I 1 representing the intensity value of the beta-ray for the last sampling period,I 2 the intensity value of the beta-ray representing the current sampling period,μ m indicating mass absorptionThe coefficients of which are such that,Vand C represents the equivalent particulate matter concentration of the current sampling period.
4. The particulate matter concentration detection device according to claim 3, wherein when the gas flow detection device detects that the gas flow in the sampling chamber is lower than a first flow preset threshold, or when a detection duration of the detector is equal to a first time preset threshold, the filter paper mounting portion replaces the filter paper, and the detector resets the sampling number of times.
5. The particulate matter concentration detection device according to claim 3, wherein the filter paper attachment unit replaces the filter paper and the detector resets the sampling number of times when the real-time particulate matter concentration calculated by the data processing unit is lower than a first preset concentration threshold.
6. The particulate matter concentration detection apparatus according to any one of claims 4 or 5, wherein the data processing portion is provided with a second time preset threshold, and when the sampling period of the detector is equal to or longer than the second time preset threshold, the data processing portion calculates an equivalent particulate matter concentration for a current sampling period and stores the equivalent particulate matter concentration for the current sampling period in the sample space in order of a sampling time axis.
7. The particulate matter concentration detection apparatus according to claim 1,
the device also comprises a temperature detection module for detecting the temperature in the sampling chamber in real time;
the data processing part calculates and obtains a beta ray intensity value after temperature compensation through a temperature compensation algorithm according to the temperature in the sampling chamber and the beta ray intensity value of the current sampling period detected by the detector;
and the data processing part calculates the equivalent particulate matter concentration of the current sampling period by a beta ray absorption method according to the beta ray intensity value after temperature compensation.
8. The particulate matter concentration detection apparatus according to claim 7, wherein the temperature compensation algorithm is expressed as follows:
S T =S-a（T-T 0 ）
wherein S is T Represents the beta-ray intensity value after temperature compensation, S represents the beta-ray intensity value without temperature compensation,arepresents the slope of the beta ray intensity value with the temperature change, T represents the temperature value in the sampling chamber, T 0 Indicating the standard temperature value set by the system.
9. The particulate matter concentration detection apparatus according to claim 8, wherein a slope of the β -ray intensity value with temperature changeaThe following conditions are satisfied:
wherein the content of the first and second substances,y i represents the temperature compensated beta-ray intensity values,x i which represents a value of the temperature inside the sampling chamber 11,xto representx i The amount of change in the amount of the second component,arepresents the slope of the beta-ray intensity value with temperature, and b represents a constant.
10. A particulate matter concentration detection method, characterized by comprising the steps of:
extracting gas to be detected to enable particles in the gas to be detected to be enriched on filter paper to form dust spots;
detecting the beta ray intensity value after the beta ray passes through the dust spot in each sampling period;
calculating the equivalent particulate matter concentration in each sampling period based on a beta ray absorption method according to the beta ray intensity value of each sampling period;
setting a sample space, wherein the sample space is used for sequentially storing the equivalent particulate matter concentration of each sampling period according to a sampling time axis sequence, and the capacity of the sample space is N;
and accumulating the equivalent particulate matter concentration of each sampling period in the sample space to obtain the real-time particulate matter concentration.
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Application publication date: 20221122 |