CN103234882B - A kind of Atmospheric particulates mass concentration inversion method based on the particulate matter flight time - Google Patents

Abstract

A kind of Atmospheric particulates mass concentration inversion method based on the particulate matter flight time, can be finally inversed by the mass concentration of particulate matter on the basis of aerodynamic grain spectrometer according to flight speed and sampling flow.According to the operation principle of aerodynamic grain spectrometer, after granule is by accelerating spout, any point on air trajectory, the particulate matter of every kind of particle diameter has unique speed u_p, the flight speed of particle can be drawn by the flight time.Flight speed and the relationship between quality of particle can be drawn by principle of conservation of momentum, aerodynamic and fluid mechanics principle, therefore can be finally inversed by the mass concentration of particulate matter by flight speed and sampling flow.The present invention is finally inversed by the mass concentration of Atmospheric particulates according to the dynamic characteristic of particulate matter；There is provided a kind of energy accurately, in real time, the inversion algorithm of on-line measurement Atmospheric particulates mass concentration.

Description

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

Technical field

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

Background technology

In recent years, along with the haze weather in the particularly flourishing city of China's most area and area frequently occurs, people are to air Quality is increasingly paid attention to.The main cause forming haze weather is that atmosphere particle concentration rises, particularly PM2.5 concentration upper Rise, cause air quality to deteriorate and visibility drastically descends degradation adverse effect.The size of particulate matter and human body in haze weather Health has close relationship, and it determines that it eventually enters into the position of respiratory tract and deposition.Poisonous, harmful in haze weather Particulate matter disseminates in atmosphere, and the mankind and ecosystem can be caused harm in various degree.Currently, the detection of Atmospheric particulates Become the important content in the fields such as environment, weather and health.

At present, the main measurement method of atmosphere particle monitoring has: oscillating balance method, Beta ray method, light scattering method.Vibration Sedimentation balance method can directly measure the concentration of particulate matter, unrelated with particle size, color etc., but its by sample temperature, humidity, The impact such as vibration, noise is bigger, and particularly in sampling process, in Atmospheric particulates, volatile organic matter loss causes measurement error Bigger.Beta ray method is unrelated with the kind of particulate matter, particle diameter, shape, color and chemical composition etc., only with the quality of particle Relevant, but affected the biggest by radiographic source, filter paper individuality difference.It addition, oscillating balance method and Beta ray method will coordinate PM10, The sicklies such as PM2.5, owing to the error of sickle will also result in measuring result error.Further, oscillating balance method and Beta ray Method cannot provide Particle density and the particle diameter distributed intelligence of each particle diameter of Atmospheric particulates, and the two parameter is all to affect health One of important parameter.Light scattering method is that the intensity size of the scattered light signal by sending after measuring the irradiation of particulate matter light is measured The mass concentration of particulate matter.At present, Atmospheric particulates calculating instrument based on light scattering method is more, such as Grimm company of Germany 1.109, the 3413 of 3330 and the Metone company of the U.S. of Technical Sourcing Internation of the U.S. etc..Light scattering method surveys the mass concentration of particulate matter Mainly measure particulate matter optics particle diameter by the scattered light intensity size of special angle, and the quality of further inverting particulate matter is dense Degree, the fluctuation of laser instrument light intensity, particle refractive index and geometry the most all can cause measurement error.

Summary of the invention

The technology of the present invention solves problem: overcome the deficiency of above-mentioned problem, it is provided that a kind of air based on the particulate matter flight time Grain material amount retrieving concentration method, can realize accurately, in real time, online, can continuous print Atmospheric particulates mass concentration monitor, energy Measure the mass concentration of PM10, PM2.5, PM1 simultaneously, and provide grain-size of atmospheric particulate substance distribution.

The technology implementation scheme of the present invention: on the basis of aerodynamic size spectrometer, a kind of based on the particulate matter flight time Atmospheric particulates mass concentration inversion method, it is achieved step is as follows:

(1) particulate matter flight time at double hot spots can, by aerodynamic size spectrometer be measured, according to the distance of double hot spots L calculates the flight speed of particle, and formula is as follows:

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

Wherein: v is the flight speed of particulate matter, L is the distance of double hot spot, and △ t is the particulate matter flight time at double hot spots. The flight speed of particulate matter can be drawn by the flight time, draw the quality of particulate matter according to flight speed.

(2), flying speed of partcles and single grain can be drawn according to the law of conservation of momentum, aerodynamic and fluid mechanics principle The relational expression of the quality of son, formula is as follows:

${\mathrm{dm}}_d=\frac{k}{C_1+C_{2}v+C_{3}ln(1-C_{4}v)}---\left(1\right)$

Wherein: dm_dBeing the quality of a certain particle diameter single particle, v is the flight speed of particulate matter, C₁For systematic features coefficient, C₂For particulate matter flight speed correction factor, C₃For the speed of gas, C₄For the correction factor of gas velocity,L is speed Degree measures point and jet opening distance, and Z is Particles transport rate.Show that the quality of a certain particle diameter single particle can this particle diameter of root The accumulated gross mass calculating this particles thing of the number of particulate matter.

(3), according to the particle diameter sum concentration information of particulate matter, calculating the gross mass of a certain particles thing, computing formula is such as Under:

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

In formula, N be particle size be the total number of particles of d, dm_dBe particle size be the quality of the single particle of d, m_dBe particle diameter be the quality of all particulates corresponding to d.After drawing the gross mass of a certain particles thing, according to the model of particle diameter Enclose and calculate the particulate matter gross mass that all particle diameters are corresponding, all particle diameter correspondence particulate matter gross masses are added in drawing particle size range Particulate matter gross mass, draw the mass concentration of surveyed particulate matter finally according to the flow used and time.

(4), by the scope of grain-size of atmospheric particulate substance, the quality of Atmospheric particulates is calculated according to the flow sampled and sampling time Concentration, computing formula is as follows:

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

In formula, D is the maximum particle diameter of the measured Atmospheric particulates arrived, and L is sampling flow, and t is the sampling time, and PM is big The mass concentration of aerated particle thing.

(5), standard aerosol particle generator is used to produce standard particle thing.Standard aerosol particle generator aperture selects 20 μm, utilize DOP solution to produce the standard particle thing of 20 groups of different solutions concentration.

(6) aerodynamic grain spectrometer, is utilized to measure the standard particle of the 20 groups of different solutions concentration obtained in step (5) The flight time of thing, the flight time calculate flight speed according to formula (6).Calculate the mark of 20 groups of different solutions concentration The quality of quasi-particulate matter, mass particle is calculated by following formula:

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

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

D_dCan be obtained by following formula:

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

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

(7), quality and the flight speed of the standard particle thing produced under the 20 groups of different solutions concentration obtained in step (6) Data are fitted, and use 5 order polynomial matchings:

Y=A+B₁x¹+B₂x²+B₃x³+B₄x⁴+B₅x⁵ (5)

Wherein, y is the inverse of the quality of single particle, and x is the flight time of particulate matter, A, B₁、B₂、B₃、B₄、 B₅It is 5 order polynomial fitting parameters, uses method of least square to obtain parameter A, B after carrying out linear fit₁、B₂、B₃、B₄、 B₅, and draw the matched curve of correspondence.Fractional part is launched by Taylor's formula in formula (1), according to matching out Curve finally determines C in formula (1)₁、C₂、C₃、C₄, k.Formula (1) fractional part is launched by Taylor's formula Formula is as follows:

$\begin{array}{c}\frac{1}{{\mathrm{dm}}_d}=\frac{C_1+C_{2}v+C_3\ln (1-C_{4}v)}{k}\\ =\frac{C_1}{k}+\frac{C_{2}v}{k}+\frac{C_3}{k}(-C_{4}v-{C_4}^2{v}^2-\\ {C_4}^3{v}^3-{C_4}^4{v}^4-{C_4}^5{v}^5\mathrm{......})\\ =\frac{C_1}{k}+\frac{C_2-C_3{C}_4}{k}v-\frac{C_3{C_4}^2}{k}{v}^2-\\ \frac{C_3{C_4}^3}{k}{v}^3-\frac{C_3{C_4}^5}{k}{v}^5\mathrm{......}\end{array}---\left(6\right)$

In formula: dm_dBeing the quality of a certain particle diameter single particle, v is the flight speed of particulate matter, C₁For systematic features Coefficient, C₂For particulate matter flight speed correction factor, C₃For the speed of gas, C₄For the correction factor of gas velocity,L For tachometric survey point and jet opening distance, Z is Particles transport rate.

Compared with measuring technology with existing Atmospheric particulates mass concentration, it is an advantage of the current invention that:

(1) present invention combines light scattering and time-of-flight carrys out inverting Atmospheric particulates mass concentration, is avoided that by particulate matter The error that refractive index is different with geometry and causes, thus improve the inversion accuracy of Atmospheric particulates mass concentration.

(2) parameter that matching of the present invention obtains is used, it is not necessary to measure the systematic parameters such as double hot spot distances and i.e. can realize particulate matter The accurate calibration of particle diameter.

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

(4) the particulate matter quality retrieving concentration in the present invention is to be obtained by the measurement flight time, and laser instrument light-intensity variation can be drawn Play scattered light intensity change, but flight time measurement result will not be produced impact, thus reduce quick to environmental change of measurement result Perception.

Accompanying drawing explanation

Fig. 1 is the flowchart of the inventive method.

Detailed description of the invention

As it is shown in figure 1, present invention Atmospheric particulates based on particulate matter flight time mass concentration inversion algorithm specifically comprises the following steps that

The first step, the particle flight time at double hot spots can be measured by aerodynamic size spectrometer, according to the distance of double hot spots L calculates the flight speed of particle, and formula is as follows:

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

Wherein: v is the flight speed of particulate matter, L is the distance of double hot spot, and △ t is the particulate matter flight time at double hot spots. The flight speed of particulate matter can be drawn by the flight time, draw the quality of particulate matter according to flight speed.

After second step, granule are by accelerating spout, any point on air trajectory, the particulate matter of every kind of particle diameter has uniquely Speed u_p.According to momentum theorem, in particulate matter, the differential momentum conservation equation of each particulate matter can use formula (7) Represent:

$\frac{d}{dt}\left(m_p{u}_p\right)={\mathrm{\Δm}}_p{u}_p+m_{p}g---\left(9\right)$

Wherein, subscript p represents particulate matter；For gas molecule collision to the mean force of particulate matter；Subscript G represents and carries gas；Z is Particles transport rate；m_pG is the gravity of particulate matter self.

Because for gas molecule collision is to the mean force of particulate matter, the gravity of particulate matter itself is the least, i.e. gravity accelerates Spend the least relative to the acceleration that gas molecule collision brings, during calculating, the impact of gravity can be ignored.Formula (9) It is reduced to:

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

Because double facula positions distance spout is close, for the ease of calculating, it is believed that Z and u_gFor constant.Finally draw particle flight The relational expression of the quality of speed and single particle, formula is as follows:

${\mathrm{dm}}_d=\frac{k}{C_1+C_{2}v+C_{3}ln(1-C_{4}v)}---\left(1\right)$

In formula: dm_dBeing the quality of a certain particle diameter single particle, v is the flight speed of particulate matter, C₁For systematic features coefficient, C₂For particulate matter flight speed correction factor, C₃For the speed of gas, C₄For the correction factor of gas velocity,L is Tachometric survey point and jet opening distance, Z is Particles transport rate.Show that the quality of a certain particle diameter single particle can this grain of root The accumulated gross mass calculating this particles thing of the number of footpath particulate matter.

3rd step, particle diameter sum concentration information according to particulate matter, calculate the gross mass of a certain particles thing, computing formula As follows:

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

In formula, N be particle size be the total number of particles of d, dm_dBe particle size be the quality of the single particle of d, m_d Be particle diameter be the quality of all particles corresponding to d.After drawing the gross mass of a certain particles thing, according to the range computation of particle diameter Go out the particulate matter gross mass that all particle diameters are corresponding, the addition of all particle diameter correspondence particulate matter gross masses is drawn the granule in particle size range Thing gross mass, draws the mass concentration of surveyed particulate matter finally according to the flow used and time.

4th step, by the scope of grain-size of atmospheric particulate substance, calculate the matter of Atmospheric particulates according to the flow of sampling and sampling time Amount concentration, computing formula is as follows:

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

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

5th step, employing standard aerosol particle generator produce standard particle thing.Aperture selects 20 μm, utilizes DOP solution Produce the standard particle thing of 20 groups of different solutions concentration.

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

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

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

D_dCan be obtained by following formula:

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

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

The quality of the standard particle thing produced under the 7th step, 20 groups of different solutions concentration that the 6th step is drawn and flight speed number According to being fitted, use 5 order polynomial matchings:

Y=A+B₁x¹+B₂x²+B₃x³+B₄x⁴+B₅x⁵ (5)

Wherein, y is the inverse of the quality of single particle, and x is the flight time of particulate matter, A, B₁、B₂、B₃、B₄、 B₅It is 5 order polynomial fitting parameters, uses method of least square to obtain parameter A, B after carrying out linear fit₁、B₂、B₃、B₄、 B₅, and draw corresponding matched curve, fractional part being launched by Taylor's formula in formula (1), obtain formula (9), C in formula (1) is finally determined according to matching parameter out₁、C₂、C₃、C₄, k.

$\begin{array}{c}\frac{1}{{\mathrm{dm}}_d}=\frac{C_1+C_{2}v+C_3\ln (1-C_{4}v)}{k}\\ =\frac{C_1}{k}+\frac{C_{2}v}{k}+\frac{C_3}{k}(-C_{4}v-{C_4}^2{v}^2-\\ {C_4}^3{v}^3-{C_4}^4{v}^4-{C_4}^5{v}^5\mathrm{......})\\ =\frac{C_1}{k}+\frac{C_2-C_3{C}_4}{k}v-\frac{C_3{C_4}^2}{k}{v}^2-\\ \frac{C_3{C_4}^3}{k}{v}^3-\frac{C_3{C_4}^5}{k}{v}^5\mathrm{......}\end{array}---\left(9\right)$

In formula: dm_dBeing the quality of a certain particle diameter single particle, v is the flight speed of particulate matter, C₁For systematic features coefficient, C₂For particulate matter flight speed correction factor, C₃For the speed of gas, C₄For the correction factor of gas velocity,L is speed Degree measures point and jet opening distance, and Z is Particles transport rate.

Y=A+B₁x¹+B₂x²+B₃x³+B₄x⁴+B₅x⁵The physical meaning of all symbols of formula；

The Atmospheric particulates flight time that 8th step, basis record, the flight time is converted into flight speed, finally by calculating Machine is finally inversed by the mass concentration of Atmospheric particulates through above-mentioned steps.

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

The above, part detailed description of the invention the most of the present invention, but protection scope of the present invention is not limited thereto, and any ripe Know those skilled in the art in the technical scope that the invention discloses, the change that can readily occur in or replacement, all should contain in the present invention Protection domain within.

Claims (1)

1. an Atmospheric particulates mass concentration inversion method based on the particulate matter flight time, it is characterised in that realize step such as Under:

(1), by aerodynamic size spectrometer measure the particulate matter flight time at double hot spots, count according to distance L of double hot spots Calculating the flight speed of particle, formula is as follows:

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

Wherein: v is the flight speed of particulate matter, L is the distance of double hot spot, and Δ t is the particulate matter flight time at double hot spots；

(2) flight speed of particulate matter, by the flight time is drawn, according to the law of conservation of momentum, aerodynamic and hydrodynamics Principle draws the relational expression of flying speed of partcles and the quality of single particle, draws the quality of particulate matter, and formula is as follows:

${\mathrm{dm}}_d=\frac{k}{C_1+C_{2}v+C_{3}ln(1-C_{4}v)}---\left(1\right)$

Wherein: dm_dBeing the quality of a certain particle diameter single particle, v is the flight speed of particulate matter, C₁For systematic features coefficient, C₂For particulate matter flight speed correction factor, C₃For the speed of gas, C₄For the correction factor of gas velocity,L is Tachometric survey point and jet opening distance, Z is Particles transport rate；

(3) utilize the quality of a certain particle diameter single particle, calculate this grain according to the number of this particles thing is accumulated The gross mass of footpath particulate matter,

Computing formula is as follows:

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

In formula, N be particle size be the total number of particles of d, dm_dBe particle size be the quality of the single particle of d, m_dBe particle diameter be the quality of all particulates corresponding to d；

(4) by the scope of grain-size of atmospheric particulate substance, the quality of Atmospheric particulates is calculated according to the flow sampled and sampling time Concentration, computing formula is as follows:

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

In formula, D is the maximum particle diameter of the measured Atmospheric particulates arrived, and L is sampling flow, and t is the sampling time, and PM is big The mass concentration of aerated particle thing；

(5), using standard aerosol particle generator to produce standard particle thing, standard aerosol particle generator aperture selects 20 μm, utilize DOP solution to produce the standard particle thing of 20 groups of different solutions concentration；

(6) aerodynamic grain spectrometer, is utilized to measure the standard particle of the 20 groups of different solutions concentration obtained in step (5) The flight time of thing, the flight time calculate flight speed according to formula (6), calculate the mark of 20 groups of different solutions concentration The quality of quasi-particulate matter, mass particle is calculated by following formula:

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

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

D_dCan be obtained by following formula:

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

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

(7), quality and the flight speed of the standard particle thing produced under the 20 groups of different solutions concentration obtained in step (5) Data are fitted, and use 5 order polynomial matchings:

Y=A+B₁x¹+B₂x²+B₃x³+B₄x⁴+B₅x⁵ (5)

Wherein, y is the inverse of the quality of single particle, and x is the flight time of particulate matter, A, B₁、B₂、B₃、B₄、 B₅It is 5 order polynomial fitting parameters, uses method of least square to obtain parameter A, B after carrying out linear fit₁、B₂、B₃、B₄、 B₅, and draw the matched curve of correspondence, in formula (1) to fractional part by Taylor's formula expansion, according to matching out Curve finally determines C in formula (1)₁、C₂、C₃、C₄, k, formula (1) to fractional part by Taylor's formula launch Formula is as follows:

$\begin{array}{c}\frac{1}{{\mathrm{dm}}_d}=\frac{C_1+C_{2}v+C_3\ln (1-C_{4}v)}{k}\\ =\frac{C_1}{k}+\frac{C_{2}v}{k}+\frac{C_3}{k}(-C_{4}v-{C_4}^2{v}^2-\\ {C_4}^3{v}^3-{C_4}^4{v}^4-{C_4}^5{v}^5......)\\ =\frac{C_1}{k}+\frac{C_2-C_3{C}_4}{k}v-\frac{C_3{C_4}^2}{k}{v}^2-\\ \frac{C_3{C_4}^3}{k}{v}^3-\frac{C_3{C_4}^5}{k}{v}^5......\end{array}---\left(6\right)$

In formula: dm_dBeing the quality of a certain particle diameter single particle, v is the flight speed of particulate matter, C₁For systematic features Coefficient, C₂For particulate matter flight speed correction factor, C₃For the speed of gas, C₄For the correction factor of gas velocity, L is tachometric survey point and jet opening distance, and Z is Particles transport rate；

(8), according to the Atmospheric particulates flight time recorded, the flight time is converted into flight speed, finally by computer The mass concentration of Atmospheric particulates it is finally inversed by through above-mentioned steps.