CN103234882A - Method for inverting mass concentration of atmospheric particulates based on flight time of particulates - Google Patents

Abstract

The invention relates to a method for inverting the mass concentration of atmospheric particulates based on the flight time of the particulates. The mass concentration of the particulates can be inverted according to the flight speed and the sampling flow on the basis of an aerodynamic particulate spectrometer. According to the work principle of the aerodynamic particulate spectrometer, the particulates with different particle sizes have only speed up at any one point on an airflow track after the particulates pass through an accelerating nozzle, so the flight speed of particles can be obtained through the flight time. The relationship between the flight speed and the mass of the particles can be obtained according to a momentum conservation theorem and aerodynamic and hydromechanical principles, so the mass concentration of the particulates can be inverted through the flight speed and the sampling flow. The method provided by the invention can be used for inverting the mass concentration of the atmospheric particulates according to the dynamic feature of the particulates and provides an inversion algorithm capable of measuring the mass concentration of the atmospheric particulates accurately, in real time and on line.

Description

A kind of Atmospheric particulates mass concentration inversion method based on the particle flight time

Technical field

The present invention relates to Atmospheric particulates mass concentration method for real-time measurement, belong to the atmosphere environment supervision technical field.

Background technology

In recent years, along with the most of area of China particularly frequently occurs with regional haze weather in flourishing city, people more and more pay attention to air quality.The main cause that forms grey haze weather is that atmosphere particle concentration rises, and the particularly rising of PM2.5 concentration causes that air quality worsens and visibility is sharply descended the degradation adverse effect.Particle size and the health of particle have close relationship in the ash haze weather, and it determines position and the deposition that it finally enters respiratory tract.Poisonous, deleterious particle thing in the ash haze weather are spread out in the air, can cause in various degree harm to human and the ecosystem.Current, the detection of Atmospheric particulates has become the important content in fields such as environment, weather and health.

At present, the main measuring method of atmosphere particle monitoring has: vibration sedimentation balance method, Beta rays method, light scattering method.The vibration sedimentation balance method can directly be measured the concentration of particle, irrelevant with particle particle diameter, color etc., it is bigger that but it is influenced by sample temperature, humidity, vibration, noise etc., particularly in the sampling process in the Atmospheric particulates volatile organic matter loss cause that measuring error is bigger.The kind of Beta rays method and particle, particle diameter, shape, color and chemical composition etc. are irrelevant, and are only relevant with the quality of particle, but are subjected to radiographic source, the individual differences affects of filter paper very big.In addition, vibration sedimentation balance method and Beta rays method all will cooperate cutters such as PM10, PM2.5, because the error of cutter also can cause measuring result error.And vibration sedimentation balance method and Beta rays method can't provide several concentration and the particle diameter distributed intelligence of each particle diameter of Atmospheric particulates, and these two parameters all are one of important parameters that influences health.Light scattering method is the mass concentration of measuring particle by the intensity size of measuring the scattered light signal that sends after particle is penetrated by illumination.At present, more based on the Atmospheric particulates calculating instrument of light scattering method, as German Grimm company 1.109,3330 and the U.S. Metone company of U.S. Technical Sourcing Internation 3413 etc.The mass concentration that light scattering method is surveyed particle mainly is to measure particle optics particle diameter by the scattered light intensity size of special angle, and the mass concentration of further inverting particle, the different of the fluctuation of laser instrument light intensity, the refractive index of particle and geometric configuration all can cause measuring error.

Summary of the invention

The technology of the present invention is dealt with problems: the deficiency that overcomes above-mentioned problem, a kind of Atmospheric particulates mass concentration inversion method based on the particle flight time is provided, can realize accurate, real-time, online, continuable Atmospheric particulates mass concentration monitoring, can measure the mass concentration of PM10, PM2.5, PM1 simultaneously, and provide the distribution of Atmospheric particulates particle diameter.

Implementer's case of the present invention: on the basis of aerodynamic size spectrometer, a kind of Atmospheric particulates mass concentration inversion method based on the particle flight time, performing step is as follows:

(1), can measure particle in the flight time of two hot spots by the aerodynamic size spectrometer, calculate the flying speed of particle according to the distance L of two hot spots, formula is as follows:

$v=\frac{L}{\mathrm{\Δt}}---\left(7\right)$

Wherein: v is the flying speed of particle, and L is the distance of two hot spots, and Δ t is that particle is in the flight time of two hot spots.Can draw the flying speed of particle by the flight time, draw the quality of particle according to flying speed.

(2), can draw the relational expression of the quality of particle flying speed and single particle according to the law of conservation of momentum, aerodynamics and fluid mechanics principle, formula is as follows:

$d{m}_d=\frac{k}{C_1+C_{2}v+C_3\ln (1-C_{4}v)}---\left(1\right)$

Wherein: dm _dBe the quality of a certain particle diameter single particle, v is the flying speed of particle, C ₁Be systematic error correction factor, C ₂Be particle flying speed correction factor, C ₃Be the speed of gas, C ₄Be the correction factor of gas velocity,

L is velocity survey point and jet opening distance, and Z is the particle mobility.Draw number that the quality of a certain particle diameter individual particle thing can this particle diameter particle of root goes out this particle diameter particle through accumulation calculating gross mass.

(3), according to the particle diameter of particle and number concentration information, calculate the gross mass of a certain particle diameter particle, computing formula is as follows:

$m_d=\underset{i=0}{\overset{N}{\mathrm{\Σ}}}d{m}_d---\left(2\right)$

In the formula, N is that the particle particle diameter is the total number of particles of d, dm _dBe that the particle particle diameter is the quality of the individual particle thing of d, m _dBe that particle diameter is the quality of the corresponding all particulates of d.After drawing the gross mass of a certain particle diameter particle, go out the particle gross mass of all particle diameter correspondences according to the range computation of particle diameter, the additions of the corresponding particle gross mass of all particle diameters are drawn particle gross mass in the particle size range, at last the mass concentration that draws the particle of surveying according to the flow that adopts and time.

(4), by the scope of Atmospheric particulates particle diameter, according to the mass concentration that the flow of sampling and sampling time calculate Atmospheric particulates, computing formula is as follows:

$\mathrm{PM}=\frac{\underset{d=0}{\overset{D}{\mathrm{\Σ}}}{m}_d}{L\·t}---\left(3\right)$

In the formula, D is the maximum particle diameter of the measured Atmospheric particulates that arrive, and L is sampling flow, and t is the sampling time, and PM is the mass concentration of Atmospheric particulates.

(5), adopt standard aerosol particle electronic generator to produce the standard particle thing.Standard aerosol particle electronic generator aperture is selected 20 μ m, utilizes DOP solution to produce the standard particle thing of 20 groups of different solutions concentration.

(6), utilize aerodynamics grain spectrometer to measure the flight time of the standard particle thing of 20 groups of different solutions concentration that obtain in the step (5), calculate flying speed according to formula (6) by the flight time.Calculate the quality of the standard particle thing of 20 groups of different solutions concentration, mass particle is calculated by following formula:

$m_p=\frac{\mathrm{\π}}{6}\·{D_d}^3\·\mathrm{\ρ}---\left(4\right)$

In the formula, ρ is the mass particle density of DOP; D _dIt is liquid-drop diameter.

D _dCan be obtained by following formula:

$D_d={\left(\frac{6\mathrm{QC}}{\mathrm{\πf}}\right)}^{1/3}---\left(8\right)$

Q is liquid supply rate in the formula, i.e. flow rate of liquid, and f is vibration frequency, C is volumetric concentration.

(7), quality and the flying speed data of the standard particle thing that produces under 20 groups of different solutions concentration that obtain in the step (6) are carried out match, adopt 5 order polynomial matches:

y＝A+B ₁x ¹+B ₂x ²+B ₃x ³+B ₄x ⁴+B ₅x ⁵ （5）

Wherein, y is the inverse of the quality of individual particle thing, and x is the flight time of particle, A, B ₁, B ₂, B ₃, B ₄, B ₅Be 5 order polynomial fitting parameters, adopt least square method to carry out obtaining parameter A, B behind the linear fit ₁, B ₂, B ₃, B ₄, B ₅, and the corresponding matched curve of drawing.Fractional part is launched by Taylor's formula in the formula (1), finally determine C in the formula (1) according to the curve that match is come out ₁, C ₂, C ₃, C ₄, the k parameter.Formula (1) to fractional part by the Taylor's formula expansion formula as follows:

$\frac{1}{d{m}_p}=\frac{C_1+C_{2}v+C_3\ln (1-C_{4}v)}{k}$

$=\frac{C_1}{k}+\frac{C_{2}v}{k}+\frac{C_3}{k}(-C_{4}v-{C_4}^2{v}^2-$

${C_4}^3{v}^3-{C_4}^4{v}^4-{C_4}^5{v}^5......)$

$=\frac{C_1}{k}+\frac{C_2-C_3{C}_4}{k}v-\frac{C_3{C_4}^2}{k}{v}^2----\left(6\right)$

$\frac{C_3{C_4}^3}{k}{v}^3-\frac{C_3{C_4}^5}{k}{v}^5......$

In the formula: dm _dBe the quality of a certain particle diameter single particle, v is the flying speed of particle, C ₁Be systematic error correction factor, C ₂Be particle flying speed correction factor, C ₃Be the speed of gas, C ₄Be the correction factor of gas velocity,

L is velocity survey point and jet opening distance, and Z is the particle mobility.

Compare with existing Atmospheric particulates mass concentration measuring technique, the invention has the advantages that:

(1) the present invention comes inverting Atmospheric particulates mass concentration in conjunction with light scattering and flight time principle, can avoid being subjected to particle refractive index and the error that cause different with geometric configuration, thereby improves the inversion accuracy of Atmospheric particulates mass concentration.

(2) parameter that adopts match of the present invention to obtain need not to measure the accurate demarcation that systematic parameter such as two hot spot distances namely can realize the particle particle diameter.

(3) the present invention realizes the fast inversion of Atmospheric particulates PM10, PM2.5, PM1.

(4) the particle quality retrieving concentration among the present invention is to obtain by the measurement flight time, and laser instrument light-intensity variation meeting causes that scattered light intensity changes, but can not exert an influence to the flight time measurement result, thereby reduces measurement result to the susceptibility of environmental change.

Description of drawings

Fig. 1 is the realization flow figure of the inventive method.

Embodiment

As shown in Figure 1, it is as follows to the present invention is based on the Atmospheric particulates mass concentration inversion algorithm concrete steps of particle flight time:

The first step, can measure particle in the flight time of two hot spots by the aerodynamic size spectrometer, calculate the flying speed of particle according to the distance L of two hot spots, formula is as follows:

$v=\frac{L}{\mathrm{\Δt}}---\left(6\right)$

Wherein: v is the flying speed of particle, and L is the distance of two hot spots, and Δ t is that particle is in the flight time of two hot spots.Can draw the flying speed of particle by the flight time, draw the quality of particle according to flying speed.

Second step, particle be by after accelerating spout, on air trajectory more arbitrarily, every kind of size particles thing has unique speed u _pAccording to theorem of momentum, the differential momentum conservation equation of each particle can be represented with formula (7) in the particle:

$\frac{d}{\mathrm{dt}}\left(m_p{u}_p\right)=<\mathrm{\&Delta;}{m}_p{u}_p>+m_{p}g---\left(9\right)$

Wherein, subscript p represents particle;

Give the mean force of particle for gas molecule collision; Subscript g represents to carry gas; Z is the particle mobility; m _pG is the gravity of particle self.

Because with respect to the mean force that gas molecule collision is given particle, the gravity of particle itself is very little, namely acceleration of gravity is very little with respect to the acceleration that gas molecule collision brings, and in computation process, can ignore the influence of gravity.Formula (9) is reduced to:

$\frac{d}{\mathrm{dt}}\left(m_p{u}_p\right)=\frac{u_g-u_p}{Z}---\left(10\right)$

Because two facula positions are very near apart from spout, for the ease of calculating, think Z and u _gBe constant.Finally draw the relational expression of the quality of particle flying speed and single particle, formula is as follows:

$d{m}_d=\frac{k}{C_1+C_{2}v+C_3\ln (1-C_{4}v)}---\left(1\right)$

In the formula: dm _dBe the quality of a certain particle diameter single particle, v is the flying speed of particle, C ₁Be systematic error correction factor, C ₂Be particle flying speed correction factor, C ₃Be the speed of gas, C ₄Be the correction factor of gas velocity, L is velocity survey point and jet opening distance, and Z is the particle mobility.Draw number that the quality of a certain particle diameter individual particle thing can this particle diameter particle of root goes out this particle diameter particle through accumulation calculating gross mass.

The 3rd step, according to the particle diameter of particle and number concentration information, calculate the gross mass of a certain particle diameter particle, computing formula is as follows:

$m_d=\underset{i=0}{\overset{N}{\mathrm{\&Sigma;}}}d{m}_d---\left(2\right)$

In the formula, N is that the particle particle diameter is the total number of particles of d, dm _dBe that the particle particle diameter is the quality of the single particle of d, m _dBe particle diameter by d the quality of all particles of correspondence.After drawing the gross mass of a certain particle diameter particle, go out the particle gross mass of all particle diameter correspondences according to the range computation of particle diameter, the additions of the corresponding particle gross mass of all particle diameters are drawn particle gross mass in the particle size range, at last the mass concentration that draws the particle of surveying according to the flow that adopts and time.

The 4th step, by the scope of Atmospheric particulates particle diameter, according to the mass concentration that the flow of sampling and sampling time calculate Atmospheric particulates, computing formula is as follows:

$\mathrm{PM}=\frac{\underset{d=0}{\overset{D}{\mathrm{\&Sigma;}}}{m}_d}{L\&CenterDot;t}---\left(3\right)$

In the formula, D is the maximum particle diameter of Atmospheric particulates, and L is sampling flow, and t is the sampling time, and PM is the mass concentration of Atmospheric particulates.

The 5th step, employing standard aerosol particle electronic generator produce the standard particle thing.Aperture is selected 20 μ m, utilizes DOP solution to produce the standard particle thing of 20 groups of different solutions concentration.

The 6th step, utilize aerodynamics grain spectrometer to measure the flight time of the standard particle thing of 20 groups of different solutions concentration that the 5th step obtained in described, calculate flying speed according to formula (6) by the flight time.Calculate the quality of the standard particle thing of 20 groups of different solutions concentration, mass particle is calculated by following formula:

$m_p=\frac{\mathrm{\&pi;}}{6}\&CenterDot;{D_d}^3\&CenterDot;\mathrm{\&rho;}---\left(4\right)$

In the formula, ρ is the mass particle density of DOP; D _dIt is liquid-drop diameter.

D _dCan be obtained by following formula:

$D_d={\left(\frac{6\mathrm{QC}}{\mathrm{\&pi;f}}\right)}^{1/3}---\left(8\right)$

Q is liquid supply rate in the formula, i.e. flow rate of liquid, and f is vibration frequency, C is volumetric concentration.

The 7th step, the 6th quality and the flying speed data that go on foot the standard particle thing that produces under 20 groups of different solutions concentration drawing are carried out match, adopt 5 order polynomial matches:

y＝A+B ₁x ¹+B ₂x ²+B ₃x ³+B ₄x ⁴+B ₅x ⁵ （5）

Wherein, y is the inverse of the quality of individual particle thing, and x is the flight time of particle, A, B ₁, B ₂, B ₃, B ₄, B ₅Be 5 order polynomial fitting parameters, adopt least square method to carry out obtaining parameter A, B behind the linear fit ₁, B ₂, B ₃, B ₄, B ₅, and the corresponding matched curve of drawing, fractional part is launched by Taylor's formula in the formula (1), obtain formula (9), finally determine C in the formula (1) according to the parameter that match is come out ₁, C ₂, C ₃, C ₄, the k parameter.

$\frac{1}{d{m}_p}=\frac{C_1+C_{2}v+C_3\ln (1-C_{4}v)}{k}$

$=\frac{C_1}{k}+\frac{C_{2}v}{k}+\frac{C_3}{k}(-C_{4}v-{C_4}^2{v}^2-$

${C_4}^3{v}^3-{C_4}^4{v}^4-{C_4}^5{v}^5......)$

$=\frac{C_1}{k}+\frac{C_2-C_3{C}_4}{k}v-\frac{C_3{C_4}^2}{k}{v}^2----\left(9\right)$

$\frac{C_3{C_4}^3}{k}{v}^3-\frac{C_3{C_4}^5}{k}{v}^5......$

In the formula: dm _dBe the quality of a certain particle diameter single particle, v is the flying speed of particle, C ₁Be systematic error correction factor, C ₂Be particle flying speed correction factor, C ₃Be the speed of gas, C ₄Be the correction factor of gas velocity,

L is velocity survey point and jet opening distance, and Z is the particle mobility.

Y=A+B ₁x ¹+ B ₂x ²+ B ₃x ³+ B ₄x ⁴+ B ₅x ⁵The physical meaning of all symbols of formula;

The Atmospheric particulates flight time that the 8th step, basis record converts the flight time to flying speed, finally is finally inversed by the mass concentration of Atmospheric particulates through above-mentioned steps by computing machine.

The non-elaborated part of the present invention belongs to techniques well known.

The above; only for part embodiment of the present invention, but protection scope of the present invention is not limited thereto, and any those skilled in the art are in the technical scope that the present invention discloses; the variation that can expect easily or replacement all should be encompassed within protection scope of the present invention.

Claims (2)

1. Atmospheric particulates mass concentration inversion method based on the particle flight time is characterized in that performing step is as follows:

(1) data message that measures by the aerodynamic size spectrometer draws the relational expression of the quality of particle flying speed and single particle according to the law of conservation of momentum, aerodynamics and fluid mechanics principle, and formula is as follows:

$d{m}_d=\frac{k}{C_1+C_{2}v+C_3\ln (1-C_{4}v)}---\left(1\right)$

In the formula, C ₁Be systematic error correction factor, C ₂Be particle flying speed correction factor, C ₃Be the speed of gas, C ₄Be the correction factor of gas velocity,

L is velocity survey point and jet opening distance, and Z is the particle mobility, and v is the flying speed of particle, dm _dIt is the quality of a certain particle diameter individual particle thing; The number that draws this particle diameter particle of quality root of a certain particle diameter individual particle thing goes out the gross mass of this particle diameter particle through accumulation calculating;

(2) according to particle diameter and the number concentration information of particle, calculate the gross mass of a certain particle diameter particle, computing formula is as follows:

$m_d=\underset{i=0}{\overset{N}{\mathrm{\&Sigma;}}}d{m}_d---\left(2\right)$

In the formula, N is that the particle particle diameter is the particle sum of d, dm _dBe that the particle particle diameter is the quality of the corresponding individual particle thing of d, m _dBe that particle diameter is the gross mass of the corresponding particle of d; After drawing the gross mass of a certain particle diameter particle, go out the particle gross mass of all particle diameter correspondences according to the range computation of particle diameter, the additions of the corresponding particle gross mass of all particle diameters are drawn particle gross mass in the particle size range, at last the mass concentration that draws the particle of surveying according to the flow that adopts and time;

(3) by measured Atmospheric particulates particle size range, according to flow and the sampling time mass concentration that calculates Atmospheric particulates of sampling, computing formula is as follows:

$\mathrm{PM}=\frac{\underset{d=0}{\overset{D}{\mathrm{\&Sigma;}}}{m}_d}{L\&CenterDot;t}---\left(3\right)$

In the formula, D is maximum particle diameter in the measured Atmospheric particulates, and L is sampling flow, and t is the sampling time, and PM is the mass concentration of Atmospheric particulates.

2. according to claims 1 described a kind of Atmospheric particulates mass concentration inversion method based on the particle flight time, it is characterized in that: the system calibrating coefficient method of described step (1) is as follows:

(11) produce the standard particle thing with standard aerosol particle electronic generator, the aperture of standard aerosol particle electronic generator is selected 20 μ m, utilizes DOP solution to produce the standard particle thing of 20 groups of different solutions concentration;

(12) utilize the aerodynamic size spectrometer to measure the flight time of the standard particle thing of the described 20 groups of different solutions concentration that obtain of step (11), calculate flying speed by the flight time, calculate the quality of the standard particle thing of 20 groups of different solutions concentration that obtain described in the step (11), mass particle is calculated by following formula:

$m_p=\frac{\mathrm{\&pi;}}{6}\&CenterDot;{D_d}^3\&CenterDot;\mathrm{\&rho;}---\left(4\right)$

In the formula, ρ is the mass particle density of DOP; D _dIt is liquid-drop diameter;

(13) quality and the flying speed of the standard particle thing that produces under 20 groups of different solutions concentration that obtain described in the step (12) are carried out match, adopt 5 order polynomial matches:

y＝A+B ₁x ¹+B ₂x ²+B ₃x ³+B ₄x ⁴+B ₅x ⁵ （5）

Wherein, y is the inverse of the quality of individual particle thing, and x is the flight time of particle, A, B ₁, B ₂, B ₃, B ₄, B ₅Be 5 order polynomial fitting parameters, adopt least square method to carry out obtaining parameter A, B behind the linear fit ₁, B ₂, B ₃, B ₄, B ₅, and provide corresponding matched curve, formula (1) fractional part is launched by Taylor's formula, finally determine C in the formula (1) according to the parameter that match is come out ₁, C ₂, C ₃, C ₄, the k parameter; Formula (1) to fractional part by the Taylor's formula expansion formula as follows:

$\frac{1}{d{m}_p}=\frac{C_1+C_{2}v+C_3\ln (1-C_{4}v)}{k}$

$=\frac{C_1}{k}+\frac{C_{2}v}{k}+\frac{C_3}{k}(-C_{4}v-{C_4}^2{v}^2-$

${C_4}^3{v}^3-{C_4}^4{v}^4-{C_4}^5{v}^5......)$

$=\frac{C_1}{k}+\frac{C_2-C_3{C}_4}{k}v-\frac{C_3{C_4}^2}{k}{v}^2----\left(6\right)$

$\frac{C_3{C_4}^3}{k}{v}^3-\frac{C_3{C_4}^5}{k}{v}^5......$

In the formula: dm _dBe the quality of a certain particle diameter single particle, v is the flying speed of particle, C ₁Be systematic error correction factor, C ₂Be particle flying speed correction factor, C ₃Be the speed of gas, C ₄Be the correction factor of gas velocity,

L is velocity survey point and jet opening distance, and Z is the particle mobility.

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