1. A dust concentration detection method based on multi-angle light scattering is characterized by comprising the following steps:

s1: when dust concentration is detected, the multi-angle light scattering detection unit is placed in a dust concentration detection environment, and AD values m output by the photoelectric sensors at two angles are obtained respectively_AD、n_AD；

S2: measuring a standard dust concentration value of the dust to be measured by adopting a filter membrane mass concentration method;

s3: according to the standard dust concentration value and AD value m_AD、n_ADRespectively establishing AD value curves m (x) and n (x);

s4: dividing the curves m (x) and n (x) into i interpolation functions m according to the spline interpolation principle_i(x) And n_i(x) Then, an AD fusion value g is calculated by utilizing a multi-angle light scattering fusion algorithm_i(x)；

S5: according to the standard dust concentration value and the AD fusion value g_i(x) Establishing a dust concentration detection regression equation G (x) of the multi-angle light scattering unit;

s6: fusing AD with a value g_i(x) And substituting into a regression equation G (x), and calculating to obtain the dust concentration value detected by the multi-angle light scattering unit.

2. The dust concentration detection method of claim 1, wherein in step S1, the multi-angle light scattering detection unit comprises: the device comprises a laser light source, an optical lens group, a light trap, photoelectric sensors I and II and corresponding detection circuits I and II;

when the detected dust enters the photosensitive area, the photoelectric sensors I and II convert the collected scattered light intensity into electric signals, and then the dust concentration value detected by the light scattering method and the corresponding AD value are obtained through the detection circuits I and II.

3. The dust concentration detection method according to claim 1 or 2, wherein the photoelectric sensors i and II are provided at scattering angles θ ═ pi/2 and 3 pi/2, respectively.

4. A dust concentration detection method according to claim 1, wherein in step S3, the spline interpolation principle specifically includes: will [0, x_n]The interval is divided into n nodes: 0<x₁<x₂<···<x_nAccording to the spline interpolation principle, the AD value curves m (x) and n (x) are divided into i interpolation functions m_i(x) And n_i(x)。

5. The dust concentration detection method according to claim 4, wherein in step S4, the calculation formula of the multi-angle light scattering fusion algorithm is as follows:

Background

The dust that the colliery is produced in the pit not only increases the risk that the operation personnel suffered from occupational disease, has reduced the visibility of production environment moreover and has increaseed the risk of dust explosion for operation personnel physical and mental health and operation environment safety all can not obtain the guarantee. Therefore, the online continuous detection of the dust concentration is a prerequisite for preventing occupational hazards of dust and guaranteeing safe production. At present, the online detection method for dust concentration which is applied more is a light scattering method. The popularization of the dust concentration detection technology based on the method proves the feasibility of the light scattering method for the online detection of the underground dust of the coal mine.

At present, Wu Fu Xiang proposes a non-powered dust concentration detection technology of single-angle light scattering, which prolongs the maintenance time; the method for accurately measuring the particle sizes of the nanometer and submicron atmospheric particles with the mu g level concentration is explored by independently researched multi-angle dynamic light scattering devices of Sun 28156; juan Carlos G Lo and mez Marti i n and the like measure the light scattering intensity of polydisperse spheres and irregular particles through simulation experiments, and the problem that the lower limit of a light scattering method is uncertain is discussed again; xueshan Han et al studied the effect of the medium surrounding the dust particles on the scattering signal based on MIE theory and found the relative refractive index due to the medium.

Researchers at home and abroad study single-angle light scattering intensity, dust concentration and influencing media from micro and macro, and even multi-angle measurement related researches of nanometer and submicron atmospheric particle sizes with mu g level concentration appear. However, the coal mine dust concentration reaches the mg level, which is at least 1000 times of that of the atmospheric environment, so that the multi-angle light scattering related research aiming at the coal mine underground dust is still lacked, and the related detection units and algorithms thereof are different.

Therefore, there is a need for a dust concentration detection method capable of reducing the relative detection error.

Disclosure of Invention

In view of the above, the present invention provides a dust concentration detection method based on multi-angle light scattering, which reduces the relative error of dust concentration detection.

In order to achieve the purpose, the invention provides the following technical scheme:

a dust concentration detection method based on multi-angle light scattering specifically comprises the following steps:

s1: when dust concentration is detected, the multi-angle light scattering detection unit is placed in a dust concentration detection environment to respectively obtain AD values m output by the photoelectric sensors (I and II) at two angles_AD、n_AD；

S2: measuring a standard dust concentration value of the dust to be measured by adopting a filter membrane mass concentration method;

s3: according to the standard dust concentration value and AD value m_AD、n_ADRespectively establishing AD value curves m (x) and n (x);

s4: dividing the curves m (x) and n (x) into i interpolation functions m according to the spline interpolation principle_i(x) And n_i(x) Then, an AD fusion value g is calculated by utilizing a multi-angle light scattering fusion algorithm_i(x)；

S5: according to the standard dust concentration value and the AD fusion value g_i(x) Establishing a dust concentration detection regression equation G (x) of the multi-angle light scattering unit;

s6: fusing AD with a value g_i(x) And substituting into a regression equation G (x), and calculating to obtain the dust concentration value detected by the multi-angle light scattering unit.

Further, in step S1, the multi-angle light scattering detection unit includes: the device comprises a laser light source, an optical lens group, a light trap, photoelectric sensors I and II (namely light scattering receiving devices), corresponding detection circuits I and II and the like;

when the detected dust enters the photosensitive area, the photoelectric sensors I and II convert the collected scattered light intensity into electric signals, and then the dust concentration value detected by the light scattering method and the corresponding AD value are obtained through the detection circuits I and II.

Further, the photosensors i and II are disposed at the scattering angles θ ═ pi/2 and 3 pi/2, respectively.

Further, in step S3, the spline interpolation principle specifically includes: will [0, x_n]The interval is divided into n nodes: 0<x₁<x₂<···<x_nAccording to the spline interpolation principle, the AD value curves m (x) and n (x) are divided into i interpolation functions m_i(x) And n_i(x)。

Further, in step S4, the calculation formula of the multi-angle light scattering fusion algorithm is:

the invention has the beneficial effects that: the invention is based on the light scattering basic principle, deduces the relation between the scattering angle and the dust concentration, determines the optimal light scattering angle, and designs a multi-angle light scattering dust concentration detection unit; and testing the photoelectric sensors of the multi-angle detection unit based on test preparation and a system, and performing data fusion on the AD values of the two photoelectric sensors by adopting a data fusion method to realize the detection of the dust concentration. The method greatly reduces the relative error of dust concentration detection.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the means of the instrumentalities and combinations particularly pointed out hereinafter.

Drawings

For the purposes of promoting a better understanding of the objects, aspects and advantages of the invention, reference will now be made to the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a schematic diagram of the basic principle of light scattering;

FIG. 2 is a schematic diagram of a multi-angle light scattering detection unit;

FIG. 3 is a schematic diagram of a test system;

FIG. 4 is a graph showing AD values of photosensors at two angles in a multi-angle light scattering dust concentration detection unit;

FIG. 5 is a diagram showing the relative error of two-angle photoelectric sensors and the dust concentration detection of a multi-angle light scattering detection unit.

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present invention in a schematic way, and the features in the following embodiments and examples may be combined with each other without conflict.

Wherein the showings are for the purpose of illustrating the invention only and not for the purpose of limiting the same, and in which there is shown by way of illustration only and not in the drawings in which there is no intention to limit the invention thereto; to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.

The same or similar reference numerals in the drawings of the embodiments of the present invention correspond to the same or similar components; in the description of the present invention, it should be understood that if there is an orientation or positional relationship indicated by terms such as "upper", "lower", "left", "right", "front", "rear", etc., based on the orientation or positional relationship shown in the drawings, it is only for convenience of description and simplification of description, but it is not an indication or suggestion that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes, and are not to be construed as limiting the present invention, and the specific meaning of the terms may be understood by those skilled in the art according to specific situations.

Referring to fig. 1 to 5, the present invention preferably discloses a dust concentration detection method based on a multi-angle light scattering dust concentration detection unit, which specifically includes the following steps:

step 1: when dust concentration is detected, the multi-angle light scattering detection unit is arranged in a detection environment to respectively obtain AD values m output by the photoelectric sensors I and II at two angles_AD、n_AD；

Step 2: according to the dust concentration test data table (namely table 1) detected by the photoelectric sensors I and II of the multi-angle light scattering dust concentration detection unit, the AD values m of the two photoelectric sensors are compared_AD、n_ADRespectively establishing AD value curves m (x) and n (x);

and step 3: according to the curve equations m (x) and n (x) of FIG. 4, m_i(x) And n_i(x) Substituting the formula of the multi-angle light scattering fusion algorithm (namely, in the formula (5), calculating the AD fusion value g_i(x)；

And 4, step 4: fusing AD with a value g_i(x) And substituting into a regression equation G (x), and calculating the dust concentration value detected by the multi-angle light scattering unit.

Design method of multi-angle light scattering dust concentration detection unit in step 2

1) Basic principle of light scattering method

The MIE scattering method is a common method for detecting the concentration of dust in a coal mine, and the basic principle is as shown in fig. 1, a beam of monochromatic parallel light (wavelength λ, intensity I0) is assumed to be incident on a coordinate O point, and a group of dust particles with refractive index m, true density ρ and diameter d emits scattered light in any spatial direction at the O point. The point P is a scattered light receiving point, r is the sagittal diameter, and theta is the scattering angle.

The point P is the superposition of the scattering intensity of each dust particle at the point, and the relation between the scattering intensity I and the concentration C of the detected dust particles is shown as the formula (1).

Assuming constant k, as in equation (2):

then, formula (1) may be changed to (3):

I＝k*C (3)

as can be seen from the formula (3): the P point scattering light intensity I is in direct proportion to the concentration C of the measured dust.

2) Multi-angle light scattering detection unit

According to equation (3), the measured dust concentration C is proportional to the light scattering intensity I and inversely proportional to the constant k.

In the detection, if the incident light and the dust are determined, the wavelength lambda and the light intensity I of the incident light₀The dust particle diameter d, the true density ρ and the refractive index m are all regarded as constant values. The magnitude of k depends on the scatter angle theta.

By mathematical deduction, the calculated value of k is the smallest and the dust concentration C has the largest measured value when θ is pi/2 or 3 pi/2.

It can be seen that scattering of light received at θ ═ pi/2 or 3 pi/2 is more advantageous for detection of dust concentration. Through the comparison of the technologies at home and abroad, the scattering angle of the light scattering method is generally selected from one of the two. If the two are combined, the error of the detection of the light scattering dust concentration is further reduced.

Different from the detection of the atmospheric particulates with the mu g level concentration, the coal mine dust concentration is larger and is generally 100-10000 times of that of the atmospheric environment, and even higher. In order to reduce the pollution of dust to the light scattering detection device, in combination with the above reasoning, light scattering receiving devices are respectively designed at the scattering angles θ ═ pi/2 and 3 pi/2, a hollow circular structure is adopted between the two angles to allow dust to rapidly pass through, and a multi-angle light scattering detection unit is obtained, as shown in fig. 2.

The multi-angle light scattering detection unit comprises a laser light source, an optical lens group, a light trap, photoelectric sensors I and II (light scattering receiving devices), detection circuits I and II and the like. When the detected dust enters the photosensitive area, the photoelectric sensors I and II convert the collected scattered light intensity into electric signals, and then the dust concentration value detected by the light scattering method and the corresponding AD value are obtained through the detection circuits I and II.

In step 3, the method for obtaining the multi-angle light scattering fusion algorithm comprises the following steps:

based on multi-angle light scattering dust concentration detection unit, in order to further reduce measurement error, consider fusing the measured data of each angle.

Data fusion is an emerging research field, and is a research on data processing developed for the specific problem that a system uses multiple data sources. Practice proves that: compared with single-source data, the method has the advantages that the limitation of the single-source data can be overcome by applying multi-source data fusion, the survivability of the system is enhanced, the reliability and the robustness of the whole system are improved, the reliability of the data is enhanced, the precision is improved, the time and space coverage rate of the whole system is expanded, the real-time performance and the information utilization rate of the system are increased, and the like.

Based on the multi-angle light scattering dust concentration detection unit shown in FIG. 2, the invention adopts a multi-source data fusion method, fuses light scattering detection data of the same detected dust object at different scattering angles, and provides a multi-angle light scattering dust detection algorithm.

And the data of different scattering angles are from a complete experimental system and reliable experiments.

1) Preparation of the test

(1) Dust sample preparation

The method comprises the steps of recovering each large coal block from the underground of a coal mine, placing the large coal block into a crusher for primary crushing, then repeatedly grinding the large coal block for multiple times by using a grinder, screening out coal powder with the median particle size of less than or equal to 75 microns by using automatic screening equipment, and finally placing the coal powder with the median particle size of less than or equal to 75 microns into a constant-temperature (25 +/-5) DEG C drying oven for 24 hours for constant-temperature treatment for later use.

(2) Instrument preparation

Standard sampling instruments: international universal manual sampler with load capacity (200 +/-20) Pa and error +/-10%;

weighing instrument: a one-tenth-ten-thousandth balance, the measuring range is 0-42 g, and the resolution is 0.01-0.1 mg;

model machine: a multi-angle light scattering dust concentration detection prototype.

(3) Test system and environment

By a quantitative dust generator (0-1000 mg/m)³) The dust generating system consists of an electrostatic dust collector, an air compression pump, a dust removal pipeline (wind cave), an air velocity measuring instrument (0-30 m/s), a computer control platform and a variable frequency fan, and is shown in figure 3. The wind speed in the dust generating system is stable, and the deviation of the wind speed uniformity is less than or equal to 5 percent under the action of the variable frequency fan; the quantitative dust generator sprays dust into the pipeline, and the relative standard deviation of the dust concentration uniformity of the cross section of the wind tunnel pipeline is less than or equal to 5%; the relative deviation of the dust concentration on the same horizontal plane in the wind tunnel is less than or equal to 2 percent.

In a laboratory, a constant temperature air conditioner is started to keep the relative humidity of the test environment less than or equal to 60 percent RH and the temperature of (25 +/-5) DEG C and stable.

(4) Test procedure

The test method is a filter membrane mass concentration method, and the dust concentration measurement principle is as follows: the dust-containing air with a certain volume is attached to a filter membrane with known mass within a certain time under the action of a sampling pump, then the sampling air volume and the mass of dust on the filter membrane are measured, and the mass concentration of the measured dust in a certain gas volume is calculated.

The formula for calculating the mass concentration of the dust is shown as formula (4):

wherein C is the mass concentration of the measured dust, mg/m³；m₁、m₂Mass g before and after membrane sampling; q is sampling flow, L/min; t is the sampling time, min.

The test procedure was as follows:

firstly, selecting a clean filter membrane with the aperture less than or equal to 0.3 mu m, placing the filter membrane in a drying oven, and keeping the temperature for 2 hours at 25 ℃; taking out the filter membrane treated at constant temperature, weighing by using a one-ten-thousandth balance, and recording the mass m of the filter membrane₁；

Secondly, starting a fan to adjust the wind speed, and starting an electrostatic dust collector, a compression pump and a quantitative dust generator to start dust generation after the wind degree of the wind cave is stable; placing the sampler and the multi-angle light scattering dust detection unit at the same horizontal position of the same section in the wind tunnel;

after a period of time, starting a sampler to sample dust after the dust concentration in the wind drift is stable; after sampling time t, ending sampling, and recording the sampling gas quantity Q;

fourthly, carefully taking out the sampled dusty filter membrane from the sampler, and putting the filter membrane into the oven again to keep the temperature at 25 ℃ for 2 hours;

fifthly, clamping the again constant-temperature dust-containing filter membrane into a balance by using tweezers for weighing, and recording the mass m of the dust-containing filter membrane₂；

Sixthly, calculating the dust mass concentration C measured by the sampler in a weighing way according to the formula (4) as a standard dust concentration value; comparing and analyzing the standard dust concentration value with the photoelectric sensor detection values and AD values of two angles of the multi-angle light scattering dust detection unit;

seventhly, adjusting an opening of the dust generator, changing the dust concentration in the wind tunnel, and repeating the first step, the third step and the sixth step to perform a comparison test under other dust concentrations;

and eighthly, closing all the equipment after the test is finished, and taking out the multi-angle light scattering dust detection unit and the sampler from the wind tunnel to be placed in a storage.

2) Multi-angle light scattering fusion

According to test preparation 1), the dust concentration values detected by the photoelectric sensors i and II at two angles of the multi-angle light scattering dust concentration detection unit and the AD value (16 bits) (with the background noise of the circuit removed) were recorded and sorted using the dust mass concentration value weighed by the filter sampling method of the sampler as a standard. Representative data were extracted after 30 trials as shown in table 1.

TABLE 1 dust concentration test data table detected by photoelectric sensors I and II of multi-angle light scattering dust concentration detection unit

AD values output by photoelectric sensors 1 and 2 at two angles of the multi-angle light scattering dust concentration detection unit are the basis of dust concentration calibration, and the plotted relation curves between the AD values and the dust concentration are respectively m (x), n (x) and shown in figure 4.

As shown in table 1, the relative errors of the dust concentration detection of the photoelectric sensor 1 and the photoelectric sensor 2 corresponding to two angles of the multi-angle light scattering dust concentration detection unit are respectively: (-8.7-14.5)%, (-7.8-14.2)%, with large relative error span and large maximum error value.

Therefore, the relative error of single-angle dust concentration detection is large, and the detection relative error still needs to be reduced.

Based on the AD values of the photoelectric sensors 1 and 2 at two angles, the invention carries out data fusion on the AD values of the photoelectric sensors and the AD values to find an AD fusion value which can reduce the relative error of dust concentration detection, namely a multi-angle light scattering fusion value.

As shown in fig. 5, the AD value curve of the photosensor 1 is m (x), and the AD value curve of the photosensor 1 is n (x). Will [0, x_n]The interval is divided into n nodes: 0<x₁<x₂<···<x_nAccording to the spline interpolation principle, the two curves are divided into i interpolation functions m_i(x) And n_i(x) In that respect Performing data fusion on the AD values of m (x) and n (x) of a certain test, and calculating a shadow area value g between the two spline curves_i(x) Is AD fusion value, and is a multi-angle light scattering fusion algorithm as shown in formula (5).

The AD values of the photoelectric sensors I and II at two angles in the table 1 are taken into formula (5) to extract an AD fusion value, which is shown in the table 2.

TABLE 2 AD fusion values for different dust concentrations

In step 4, based on the test data in table 2, a regression equation G (x) for dust concentration detection of the multi-angle light scattering unit is established, wherein x is the AD fusion value g of the multi-angle light scattering detection unit_i(x) And carrying the value into G (x) to calculate the concentration value of the measured dust.

And (3) verifying by a comparison test:

the embodiment designs a dust concentration detection method based on a multi-angle light scattering dust concentration detection unit and a fusion detection algorithm. The core of the fusion detection algorithm is to detect relative errors, which will be verified experimentally below.

Writing a multi-angle light scattering dust concentration detection algorithm into the multi-angle light scattering detection unit, performing a dust concentration detection test on the multi-angle light scattering detection unit by using the same method based on the test preparation in the step 3, and respectively recording dust concentration measured values of the photoelectric sensor I, the photoelectric sensor II and the multi-angle light scattering detection unit. Taking typical data of 50 test data, the comparative graph of the detected relative errors is shown in FIG. 5. As can be seen from FIG. 5, the relative detection error of the multi-angle light scattering detection unit is less than or equal to 9.5%, 4.6% less than that of the photoelectric sensor I, and 4.4% less than that of the photoelectric sensor II.

Finally, the above embodiments are only intended to illustrate the technical solutions of the present invention and not to limit the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions, and all of them should be covered by the claims of the present invention.