CN201063015Y - Apparatus for measuring permeance ratio of particle using microseism method - Google Patents

Abstract

The utility model discloses a particles measuring device with transmissivity pulsation. A narrow beam illuminates the flowing particles and produces a transmissivity pulsation signal, and such requirements as data collecting speed, data collecting quantity, storage quantity and processing quantity are lowered and through the detection by a photoelectric detector and adopting an analog circuit processing signal, thus shortening the data processing time and realizing the real-time measuring. A reference light detection is added to obtain the changing information of light strength and has a calibration function, which can avoid the influent to the measuring results caused by the instability of light source, and realize the testing of average size and concentration of particles at the same time. The particle size and a beam section size are not confined by Gregory method, which can measure the scope of the particle size. The utility model can be used in various fields involved measurement of particle size such as scientific research, production and process control of chemical energy, environmental protection, water quality detection, etc.

Description

Transmittance pulsation method particle measurer

Technical field

The utility model relates to a kind of measurement mechanism that can measure particle mean grain size and concentration simultaneously, and particularly a kind of transmittance pulsation method particle measurer belongs to field of measuring technique.Can be used for a lot of fields that scientific research, production of chemical energy and process control, environmental protection, water quality detection etc. relate to particle sizing.

Background technology

In most of optical particulate measuring techniques, generally all the light signal that measures in the certain hour scope is averaged, purpose is to eliminate the signal fluctuation that some accidentalia are brought.The source of these signal fluctuations has nothing in common with each other, and some and tested particle have nothing to do, as the intrinsic noise of photoelectric device; Some then is the information that certain specific character of particle itself provides to external world, as since in the measurement zone different amounts of particles constantly and size-grade distribution thereof change the pulsation of the optical signal transmissive that causes.For the former, must manage during measurement to eliminate; And,, then might from the sort signal pulsation, obtain the information of relevant particle if can set up suitable theoretical description system for the latter, delustring pulsation method is exactly to utilize a kind of optical means of this information measurement grain diameter and concentration.

Gregory had proposed the transmittance pulsation method first in 1985, can measure the mean grain size and the concentration (J.Gregory of particle simultaneously, Turbidity Fluctuations in Flowing Suspensions, Journal of Colloid andInterface Science, Vol.105, No.2,1985:357-371).With a branch of narrow laser radiation sample, measuring principle is seen Fig. 1.Lasing beam diameter is D _B, corresponding illumination cross section is $A_M=\mathrm{\&pi;}{\mathrm{<figure-callout\; id="2"\; label="D\; B"\; filenames="Y20072007174500131.png"\; state="\{\{state\}\}">D</figure-callout>}}_B^{}/4,$ The particle mean grain size is D _P, sample area optical illumination thickness is L.With light intensity is I ₀Incident light irradiation, one section long time range 0, t _sThe interior optical signal transmissive I (t) that measures, I (t) is pulsed in time.Can calculate transmitance T (t)=I (t)/I ₀Mean value e{T} and standard deviation thereof _T

$e\left\{T\right\}=\frac{1}{t_s}{\&Integral;}_0^{t_s}T\left(t\right)\mathrm{dt}---\left(1\right)$

${\mathrm{\&sigma;}}_{\mathrm{<figure-callout\; id="2"\; label="T"\; filenames="Y20072007174500131.png"\; state="\{\{state\}\}">T</figure-callout>}}^2=\frac{1}{t_s}{\&Integral;}_0^{t_s}{[T\left(t\right)-e\{T\left\}\right]}^2\mathrm{dt}---\left(2\right)$

Can obtain the mean grain size D of particle by the transmittance pulsation method model of Gregory _PWith volumetric concentration C _V:

$D_P=\frac{D_B}{\sqrt{-\ln e\left\{T\right\}}}\ln [\frac{{\mathrm{\&sigma;}}_T}{e\left\{T\right\}}+\sqrt{{\left(\frac{{\mathrm{\&sigma;}}_T}{e\left\{T\right\}}\right)}^2+1}]---\left(3\right)$

$C_V=\frac{{2D}_P}{3L}\ln e\left\{T\right\}---\left(4\right)$

In the Gregory method, require beam diameter smaller, but require beam diameter big simultaneously more than grain diameter so that there are enough signal ripple amplitudes to obtain the transmitance standard deviation.This has limited the measurement range and the accuracy of grain diameter.

Secondly, adopt at present the transmittance pulsation method aspect signals collecting mainly based on the acquisition of transmission optical signal sequence, signal Processing is finished by computing machine.This data collecting card of having relatively high expectations (A/D card) sampling rate, bigger computer stored resource and certain CPU processing time, unfavorable to real-time measurement.

Summary of the invention

The utility model purpose is on the particle sizing technical foundation of Gregory, the measurement range of continuation grain diameter, and solve problems such as Gregory method data processing difficulty, accuracy of measurement are not high.Secondly, adopt analog processing circuit replacement computer signal Processing, reduce requirement, saving signal processing time, realize fast, measure in real time the data capture card.Realization is to online, the real-time monitoring of grain graininess and concentration.

The technical solution of the utility model is, a kind of transmittance pulsation method particle measurer, be characterized in, it is made of measurement zone, the reference light detector that obtains incident intensity, arrow beam of light generator, incident optical signal detector and the connected signal processing apparatus of generation light beam dimension scope 10 microns to 1.5 millimeters, and incident optical signal detector and reference light detector adopt photodetector.

Described arrow beam of light generator is made of the laser instrument, beam expander, convex lens or the lens combination that produce parallel beam, and the angle pencil of ray of being launched by laser instrument is assembled by convex lens or lens combination behind beam expander, and near the Rayleigh region focus obtains arrow beam of light.

Described arrow beam of light generator constitutes by the laser instrument that produces parallel beam with at the diaphragm or the light transmitting fiber of light signal transmitting terminal and the setting of light signal receiving end, and diaphragm or light transmitting fiber that the angle pencil of ray of launching by laser instrument is provided with on the direction of propagation obtain arrow beam of light.

Described arrow beam of light generator is made of the laser instrument and the infinitesimal signal sensor that produce parallel beam, and described infinitesimal photodetector is made of the photodetection unit of being made by silicon optical thin film material of small light-receiving area.

The hole shape of the diaphragm in the described arrow beam of light generator is rectangular opening or circular hole, the light transmitting fiber sensitive surface be shaped as circular port, the sensitive surface of infinitesimal signal sensor is shaped as circular or polygonal shape.

Described signal processing apparatus comprises analogue signal processor and signal subsequent treatment device, described analogue signal processor is made up of amplifier, low-pass filter, Hi-pass filter, RMS processor and A/D card, the detected transmitted light fluctuating signal of transmitted light detector amplifies by amplifier, one the tunnel obtains the signal that transmitted light mean value e{I} is expressed as S1 through low-pass filter, and another road directly obtains being expressed as the mean value of the transmitted light fluctuating signal square of S2 ' through the RMS processor $e\left\{I^2\right\}=e{\left\{I\right\}}^2+{\mathrm{\&sigma;}}_{\mathrm{<figure-callout\; id="2"\; label="I"\; filenames="Y20072007174500131.png"\; state="\{\{state\}\}">I</figure-callout>}}^2$ Or by obtain being expressed as the transmitted light fluctuating signal standard deviation square value σ of S2 behind the Hi-pass filter again through the RMS processor _I ², reference light detector output obtains showing the incident optical signal I into S0 after another amplifier amplifies ₀Described signal subsequent treatment device comprises totalizer, multiplier, divider, logarithmic amplifier, must export lne{T by S0, S1, S2, S2 ' signal that analogue signal processor obtains to last S3 output lne{T}, S4 by totalizer, multiplier, divider, logarithmic amplifier computing ²}/lne{T} enters data acquisition A/D card.

The beneficial effects of the utility model: measurement mechanism is simple, inexpensive, can realize on-line monitoring.Owing to adopt the mimic channel signal processing module, reduced requirement to aspects such as data picking rate, data acquisition amount, amount of data storage and data processing amounts, shortened data processing time greatly, can realize real-time measurement.In analog signal processing circuit, add the reference light detection and be used to obtain the incident intensity change information, reference light is surveyed and has been played corrective action, can effectively avoid the fixed disturbing effect to measurement result of flashing.Can realize simultaneously the multiparameter (particle mean grain size and concentration) of particle being tested.Grain diameter and beam cross section size are not had the restriction of Gregory method, and it is big to survey the grain diameter scope.Can be used for a plurality of fields that scientific research, production of chemical energy and process control, environmental protection, water quality detection etc. relate to particle sizing.

Know-why:

The utility model is based on the Gregory method and sets up new data processing model, and is different with the Gregory method, and the transmittance pulsation signal adopts transmitance mean value e{T} and transmitance mean square e{T in the utility model ²Express.

$e\left\{T^2\right\}=\frac{1}{t_s}{\&Integral;}_0^{t_s}{T}^2\left(t\right)\mathrm{dt}---\left(5\right)$

Transmitance mean value e{T} by

$\ln e\left\{T\right\}=-\frac{1.5L}{D_P}{C}_V---\left(6\right)$

Expression,

Transmitance mean square e{T ²And the transmitance standard deviation _TThere is relation $e\left\{T^2\right\}=e{\left\{T\right\}}^2+{\mathrm{\&sigma;}}_{\mathrm{<figure-callout\; id="2"\; label="T"\; filenames="Y20072007174500131.png"\; state="\{\{state\}\}">T</figure-callout>}}^2,$ And can by

$\ln e\left\{T^2\right\}=-\frac{1.5L}{D_P}{C}_V[2-\mathrm{\&chi;}\left(\mathrm{\&Lambda;}\right)]---\left(7\right)$

Expression.Wherein fundamental function χ (Λ) can by

$\mathrm{\&chi;}\left(\mathrm{\&Lambda;}\right)=\underset{0}{\overset{+\&infin;}{\&Integral;}}{F}_S\&CenterDot;\frac{2{\mathrm{<figure-callout\; id="1"\; label="J"\; filenames="Y20072007174500131.png,Y20072007174500151.png"\; state="\{\{state\}\}">J</figure-callout>}}_1^2\left(u\right)}{u}\mathrm{du}---\left(8\right)$

Find the solution and obtain.F _SBe the distribution factor of light beam light intensity on the cross section, also be applicable to circular Gaussian beam, circular uniform beam, rectangular light beam and polygon light beam etc.For Gaussian beam F _SFor

For the equally distributed circular light beam F of light intensity _SBe [2J ₁(u Λ)/u Λ] ²Λ=D _B/ D _PBe the ratio of beam diameter and grain diameter.Fundamental function χ (Λ) and Λ=D _B/ D _PThere is single valued relation,

Can get χ (Λ) and e{T} and e{T by data processing model formula (6) and (7) combination ²Relation:

$\mathrm{\&chi;}\left(\mathrm{\&Lambda;}\right)=2-\frac{\ln e\left\{T^2\right\}}{\ln e\left\{T\right\}}---\left(9\right)$

In the actual test, can adopt the mimic channel method to obtain by the transmittance pulsation signal that measures, substitution formula (9) can obtain the test number of χ (Λ).χ (Λ) can calculate as numerical value formula (8), and Fig. 7 is the numerical result of χ (Λ).Can on curve, find corresponding Λ value by χ (Λ) numerical value that test obtains, in conjunction with beam diameter D _BCan obtain grain diameter D _P, and can calculate solids volume concentration C by formula (6) or (7) _V

When beam diameter during much larger than grain diameter (Λ 〉=3), standard deviation is much smaller than transmitance mean value.Therefore, exist $\mathrm{\&chi;}\left(\mathrm{\&Lambda;}\right)\&ap;-\frac{1}{\ln e\left\{T\right\}}\frac{{\mathrm{\&sigma;}}_T^2}{e{\left\{T\right\}}^2}$ And numerically χ (Λ) approaches Λ ^-2Can get thus

$D_P=D_B\sqrt{\frac{1}{-\ln e\left\{T\right\}}}\&CenterDot;\frac{{\mathrm{\&sigma;}}_T}{e\left\{T\right\}}---\left(10\right)$

In like manner, at standard deviation during much smaller than transmitance mean value in the formula (3) $\ln [\frac{{\mathrm{\&sigma;}}_T}{e\left\{T\right\}}+\sqrt{{\left(\frac{{\mathrm{\&sigma;}}_T}{e\left\{T\right\}}\right)}^2+1}]\&ap;\frac{{\mathrm{\&sigma;}}_T}{e\left\{T\right\}},$ The approximate expression that obtains formula (3) thus is consistent with formula (10).This expression: the Gregory method is the special circumstances when beam diameter is much larger than grain diameter in the utility model theoretical model.

The used theoretical model of the utility model does not have restriction in the Gregory method to the relation of beam diameter and grain diameter.Therefore, can measure the grain diameter scope and want much wide.Secondly, the Gregory method requires the light intensity in the beam cross section evenly to distribute, and in this model the beam cross section intensity factor can be grasped flexibly, and for example desirable Gaussian beam is shone particle system.In addition, can find that from χ (Λ) curve near χ Λ ≈ 1 (Λ) has bigger slope absolute value, illustrate in this scope transmittance pulsation method to have higher measuring accuracy, and the area measure precision that Gregory is suitable for is obviously on the low side.

Description of drawings

Fig. 1 transmission fluctuation method measuring principle figure;

Fig. 2 analog signal processing system;

Fig. 3 signal subsequent treatment system;

Fig. 4 the utility model measurement mechanism embodiment 1 synoptic diagram;

Fig. 5 the utility model measurement mechanism embodiment 2 synoptic diagram;

Fig. 6 the utility model measurement mechanism embodiment 3 synoptic diagram;

The curve map of χ (Λ) under the circular uniform beam situation of Fig. 7.

Embodiment

The reference light grain measurement mechanism of a kind of transmittance pulsation method, be characterized in that it is made of measurement zone, the reference light detector that obtains incident intensity, arrow beam of light generator, optical signal detection device and the connected signal processing apparatus of generation light beam dimension scope 10 microns to 1.5 millimeters.Reference light detector in the device is used to monitor the fluctuation of incident intensity, avoids test result is disturbed.During no particle, measure optical signal transmissive and reference optical signal simultaneously in the debug phase measurement zone, the enlargement factor of adjusting reference optical signal equates optical signal transmissive and reference optical signal.

The utility model measurement mechanism embodiment 1:

By shown in Figure 4, described arrow beam of light generator is made of the laser instrument 19, beam expander 22, convex lens or the lens combination 23 that produce parallel beam.The light beam of being launched by laser instrument 19 is assembled by convex lens or lens combination 23 behind beam splitter 20 and beam expander 22, and near the Rayleigh region focus obtains arrow beam of light.Arrow beam of light is received by photodetector 3 behind receiver lens 24 by the transmitted light behind the measurement zone 2.Beam splitter 20 and reference light detector 21 are used to monitor the fluctuation of incident intensity.

The utility model measurement mechanism embodiment 2:

By shown in Figure 5, it comprises laser instrument 19, beam splitter 20, reference light detector 21, beam expander 22.Arrow beam of light generator in the present embodiment is made of diaphragm or the light transmitting fiber in light signal transmitting terminal and the setting of light signal receiving end.Diaphragm or light transmitting fiber that the angle pencil of ray of launching by laser instrument is provided with on the direction of propagation obtain arrow beam of light.Diaphragm is set to the place ahead diaphragm 25 and rear diaphragm 26, and both can choose one or be used in combination wantonly.The transmitted light of the angle pencil of ray that laser instrument 19 is launched after diaphragm 25 one-tenth arrow beam of lights in the place ahead are by measurement zone 2 received by photodetector 3 through rear diaphragm 26 by the transmitted light of angle pencil of ray after passing through measurement zone 2 that photodetector 3 receives or laser instrument 19 is launched.

The utility model measurement mechanism embodiment 3:

By shown in Figure 6, it comprises laser instrument 19, beam splitter 20, reference light detector 21, beam expander 22, measurement zone 2 and photodetector 3.Characteristics are, arrow beam of light generator described in the present embodiment is by laser instrument 19, beam splitter 20, beam expander 22 with the employing micropore diaphragm before placing transmitted light detector 3 or fibre-optic arrow beam of light guide 27 is formed or be made of the laser instrument and the infinitesimal signal sensor of generation parallel beam, and described infinitesimal photodetector is made of the photodetection unit of being made by silicon optical thin film material of small light-receiving area.

By Fig. 2, shown in Figure 3, signal processing apparatus comprises analogue signal processor and signal subsequent treatment device.

Described analogue signal processor is made up of amplifier, low-pass filter, Hi-pass filter and r.m.s. RMS processor, transmitted light detector 3 detected transmitted light fluctuating signals amplify by amplifier 4, one the tunnel obtains the signal that transmitted light mean value e{I} is expressed as S1 through low-pass filter 5, and another road directly obtains being expressed as the mean value of the transmitted light fluctuating signal square of S2 ' through r.m.s. RMS processor 7 (input of cross-over connection Hi-pass filter 6 and output terminal) $e\left\{I^2\right\}=e{\left\{I\right\}}^2+{\mathrm{\&sigma;}}_I^2$ Or by obtaining showing not being the transmitted light fluctuating signal standard deviation square value σ of S2 through RMS processor 7 again behind the Hi-pass filter 6 _I ², reference light detector 8 output obtains showing the incident optical signal I into S0 after another amplifier 9 amplifies ₀

Described signal subsequent treatment device comprises totalizer, multiplier, divider, logarithmic amplifier.Must export lne{T by S0, S1, S2, S2 ' signal that analogue signal processor obtains to last S3 output lne{T}, S4 by totalizer, multiplier, divider, logarithmic amplifier computing ²}/lne{T} enters data collecting card (A/D card).Specifically: S0 and S1 obtain transmitance mean value e{T} through divider 11, are obtained square e{T} of transmitance mean value again by multiplier 13 ²S0 obtains incident intensity square through multiplier 12, obtains the standard deviation of transmitance again through divider 14 with S2 _T ²Square e{T} by the transmitance mean value of multiplier 13 output ²Standard deviation with the transmitance of divider 14 output _T ²Obtain the mean value e{T of transmitance square through totalizer 15 ², obtain lne{T through logarithmic amplifier 16 again ².Divider 11 obtains transmitance mean value e{T} and obtains lne{T} through logarithmic amplifier 17 and be expressed as S3.The lne{T of logarithmic amplifier 16 and 17 outputs ²And lne{T} obtain lne{T through divider 18 ²}/lne{T} is expressed as S4.Signal S3 and S4 send Computer Processing can get particle mean grain size and concentration through data collecting card.

When the signal of input when being S2 ', the signal of divider 14 outputs is mean value e{T of transmitance square ², with e{T ²Directly send logarithmic amplifier 16 to obtain lne{T ².Therefore, multiplier 13 and totalizer 15 can be saved.

In the actual test, do an explanation in conjunction with Fig. 2, Fig. 3:

1) transmitted light detector 3 measures the transmitted light fluctuating signal behind signal amplifier 4 pre-amplifications, one the tunnel sends into low-pass filter 5 obtains transmitted light mean value e{I} and is expressed as S1, and the standard deviation square value σ that is expressed as S2 that RMS processor 7 (as the AD536 chip module) obtains the transmitted light fluctuating signal is sent on another road after Hi-pass filter 6 filtering _I ²Or directly send into the mean value that RMS processor 7 obtains being expressed as the transmitted light fluctuating signal square of S2 ' without Hi-pass filter 6 $e\left\{I^2\right\}=e{\left\{I\right\}}^2+{\mathrm{\&sigma;}}_I^2;$

2) gather incident optical signal I by reference light detector 8 ₀, the signal list after amplifier 9 amplifies is S0 and is gathered by A/D card 10 after the analog signal processing module in conjunction with above-mentioned two road signal S1, the S2 that obtains or S2 ' and to send Computer Processing, obtains characteristic signal e{T}=e{I}/I ₀And e{T ²}=e{T} ²+ (σ _I/ I ₀) ²

3) by shown in Figure 3, above-mentioned 1) and 2) step the S0 S1, the S2 that obtain or the S2 ' calculation process by the signal subsequent treatment device formed by totalizer 15, multiplier 12,13 dividers 11,14,18 logarithmic amplifiers 16,17, last S3 output lne{T}, S4 export lne{T ²}/lne{T} enters A/D card 10.

When adopting the signal processing circuit of Fig. 2, S1 exports e{I}, and S2 exports σ _I ²(adopting the form of Hi-pass filter), S0 output incident intensity I ₀Then can get

$e\left\{T\right\}=\frac{e\left\{I\right\}}{I_0}$

$e\left\{T^2\right\}=e{\left\{T\right\}}^2+{\left(\frac{{\mathrm{\&sigma;}}_I}{I_0}\right)}^2---\left(11\right)$

When the signal processing circuit that adopts Fig. 2, when not using Hi-pass filter, S2 ' exports e{I ².Formula (11) is

$e\left\{T\right\}=\frac{e\left\{I\right\}}{I_0}$

$e\left\{T^2\right\}=\frac{e\left\{I^2\right\}}{I_0^2}---\left(12\right)$

When adopting the subsequent process circuit of Fig. 3, two road signals of output promptly are lne{T} and lne{T ²}/lne{T}.

Substitution formula (9) can obtain the numerical value of function χ (Λ), and χ (Λ) can calculate as numerical value formula (8), and Fig. 7 is the numerical result of χ (Λ).Can on curve, find corresponding Λ value by χ (Λ) numerical value that this device to test obtains, in conjunction with beam diameter D _BCan obtain grain diameter D _P, and can calculate solids volume concentration C by formula (6) or (7) _V

Claims (6)

1. transmittance pulsation method particle measurer, it is characterized in that it is made of measurement zone, the reference light detector that obtains incident intensity, arrow beam of light generator, photodetector and the connected signal processing apparatus of generation light beam dimension scope 10 microns to 1.5 millimeters.

2. transmittance pulsation method particle measurer according to claim 1, it is characterized in that, described arrow beam of light generator is made of the laser instrument, beam splitter, beam expander, convex lens or the lens combination that produce parallel beam, the angle pencil of ray of being launched by laser instrument is behind beam expander, assemble by convex lens or lens combination, near the Rayleigh region focus obtains arrow beam of light.

3. transmittance pulsation method particle measurer according to claim 1, it is characterized in that, described arrow beam of light generator constitutes by the laser instrument that produces parallel beam with at the diaphragm or the light transmitting fiber of light signal transmitting terminal and the setting of light signal receiving end, and diaphragm or light transmitting fiber that the angle pencil of ray of launching by laser instrument is provided with on the direction of propagation obtain arrow beam of light.

4. transmittance pulsation method particle measurer according to claim 1, it is characterized in that, described arrow beam of light generator is made of the laser instrument and the infinitesimal signal sensor that produce parallel beam, and described infinitesimal photodetector is made of the photodetection unit of being made by silicon optical thin film material of small light-receiving area.

5. according to claim 3,4 described transmittance pulsation method particle measurers, it is characterized in that, diaphragm in the described arrow beam of light generator is shaped as rectangular opening or circular hole, the light transmitting fiber sensitive surface be shaped as circular port, the sensitive surface of infinitesimal signal sensor is shaped as circular or polygonal shape.

6. transmittance pulsation method particle measurer according to claim 1, described signal processing apparatus comprises analogue signal processor and signal subsequent treatment device, described analogue signal processor is made up of amplifier, low-pass filter, Hi-pass filter, RMS r.m.s. processor, the detected transmitted light fluctuating signal of transmitted light detector amplifies by amplifier, one the tunnel obtains the signal that transmitted light mean value e{I} is expressed as S1 through low-pass filter, and another road directly obtains being expressed as the mean value of the transmitted light fluctuating signal square of S2 ' through r.m.s. RMS processor $e\left\{I^2\right\}=e{\left\{I\right\}}^2+{\mathrm{\&sigma;}}_I^2$ Or obtain being expressed as the transmitted light fluctuating signal standard deviation square value σ of S2 again through r.m.s. RMS processor by Hi-pass filter _I ², reference light detector output obtains showing the incident optical signal I into S0 after another amplifier amplifies ₀Described signal subsequent treatment device comprises totalizer, multiplier, divider, logarithmic amplifier, must export lne{T by S0, S1, S2, S2 ' signal that analogue signal processor obtains to last S3 output lne{T}, S4 by totalizer, multiplier, divider, logarithmic amplifier computing ²}/lne{T} enters data acquisition A/D card.

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