CN101029863B - Method and apparatus for on-line measuring microparticle in water - Google Patents

Abstract

A method for on-line measuring micro-particle in water includes setting pipe flowing through by water sample to be measured to be flat pipe, arranging sampling window at middle of said flat pipe, utilizing plate parallel light as light source and utilizing linear array CCCD component as light receiver.

Description

Tiny particle in water On-line Measuring Method and device

Technical field:

The present invention relates to a kind of On-line Measuring Method and device of tiny particle in water, it can quantitatively record the size and the quantity of particle in the water, can judge the degree of purity of water thus, belongs to the water gaging technical field.

Background technology:

Along with the raising of the development of society, living standards of the people with to the concern more of self health, the water quality requirement of domestic water is improved constantly, thus water quality measurement is also had higher requirement.Original widely used turbidimetry can not meet the demands fully.At first, along with the turbidity of water is more and more lower, the resolution of turbidimetry and order of accuarcy can not adapt to Testing requirement gradually; Secondly, turbidity is expressed is the situation of the total amount of impure and microorganism in the water, can't obtain the information of impurity and microbe granular size, and we wishes to obtain these information very much sometimes, especially the particulate of diameter 2～20 μ m.The very strong bacterium of certain pathogenicity in the water for example, it has certain size, when negligible amounts, is difficult to determine whether contain this bacterium in the water with the method for measuring turbidity.Therefore come the evaluating water quality quality with the method for the quantity of size that can detect particle in the water and particle, more and more come into one's own.

Existing molecule detects and mainly contains three kinds of methods, electro-induction method, light blockage method, light scattering or diffraction approach.

The way of electro-induction method is: detected water sample is added the electrolytic solution that electrolysis plasmogamy becomes to have certain conductance, make this solution by a fine pipeline, the electric conductivity value at measuring channel two ends, when in the pipeline particulate being arranged, pipeline position conductive section diminishes, cause the electric conductivity value of pipe ends to reduce,, can extrapolate the size of particulate according to the quantity that electric conductivity value reduces.This method requires particulate one by one through piping, and requires pipeline very thin to obtain certain Measurement Resolution.Also require in addition water sample is made into electrolytic solution, be difficult to realize on-line measurement.Block easily because of pipeline is very thin in actual the use, safeguard difficulty.

The ultimate principle of light blockage method is the barrier effect (absorption, scattering etc.) of particulate to light, and the light intensity through water sample is changed.General structure is: detected water sample is from transparent water sample channel flow mistake, and a branch of directional light passes the water sample pipeline, accepts by photosensitive device.This method also requires particulate one by one through piping, so pipeline needs enough carefully obstruction easily in actual the use.In addition since this method light receptor area much larger than the particulate area, stopping of particulate to the influence of light intensity and small, the noise that easily is accepted device and amplifying circuit floods, therefore the Measurement Resolution of this method is lower, existing this quasi-instrument generally can only be measured the approximate range of particulate, for example 3～5 μ m; 6～9 μ m or the like can't obtain accurate numerical value.Because particulate of different nature is different with dispersion effect to the absorption of light, that is to say that in addition onesize but different in kind particulate is to the blocking effect difference of light, this will influence the accuracy of measurement.

Light scattering or diffraction approach are to utilize particulate to scattering of light or diffraction, and measuring light obtains the information of particle size by the scattered intensity behind the water sample or the position of diffraction light.This method generally also needs particulate one by one by measurement zone, therefore also must use tubule, and scattered intensity is very faint, is submerged in easily in the parasitic light (arriving the light of accepting device by non-scattering approach).It is complicated that the position (striped) of measurement diffraction light is also calculated the work of particle size thus, especially online detection of particles is under situation about moving, and need the face battle array optical receiver that enough resolution is arranged, because diffraction light intensity is very weak and the influence of system noise, measuring accuracy can be greatly affected.These class methods exist tubule easily to stop up equally, problem difficult in maintenance, and scattered light method also exists particulate of different nature the light scattering effect difference to be influenced the problem of accuracy of measurement in addition.

Summary of the invention:

The objective of the invention is to improve and eliminate following three problems that exist in existing method and the technology, thus realize online, measure the target of diameter 1～50 μ m particle size in the water more accurately.

(1) need measure one by one because of particulate and have the tubule road, bring difficult in maintenance;

(2) signal to noise ratio (S/N ratio) is low, and the measuring accuracy of grain size is not high, thereby this quasi-instrument is referred to as particle collector mostly at present;

(3) character of particulate is relevant with measurement result.

For achieving the above object, design of the present invention is:

Use the ultimate principle of light blockage method to measure, (1) reduces the area of optical receiving set spare greatly for improving signal to noise ratio (S/N ratio), makes it can be comparable with the area of particulate, and the light intensity that receives when particulate shading and no particulate shading are arranged like this will have bigger variation; (2) the optical receiving set spare of hundreds of small sizes is in one line, forming length is the linear array of 3～gmm, work simultaneously, having solved common light blockage method accepts device area and reduces, the tubule diameter also needs the corresponding problem that reduces, also can cancel tubule, sampling water field width degree is brought up to 3～8mm, solve the tubule obstructing problem; (3) linear array optical receiving set spare is carried out high-speed sampling, therefore under the not high situation of water velocity, can collect the particulate whole process that light intensity changes when flowing through optical receiving set spare, the light intensity signal that collects has a decline process (the particulate projection progresses into optical receiving set spare), stationary process (particulate is projected in the optical receiving set spare), and uphill process (optical receiving set spare is left in the particulate projection gradually), under the situation that water velocity is fixed, from light intensity signal fall time, or rise time or stationary time just can calculate the size of particulate, and the size of particulate is calculated in the variation that need not to rely on light intensity signal intensity.Having solved particulate of different nature influences the problem of accuracy of measurement to light occlusion effect difference.

Basic principle schematic shown in figure (1), the detected water sample flat pipeline of flowing through, the center section of this pipeline is exactly a sampling window, uses the line array CCD device as optical receiving set spare, the height of sampling window is the height (10～20 μ m) of each pixel of line array CCD; Length is that (3～10mm), thickness is flat tube thickness (about 0.5mm), and light source is the sheet directional light for the length of 300～500 pixels of CCD.When sampling window has particulate through out-of-date, the light intensity that the corresponding CCD pixel receives will change, and by the grain size difference following several situation be arranged:

(1) particle diameter is less than the height of CCD pixel, and particle only influences a pixel light intensity, and particle through the process of CCD and the light intensity signal that receives as shown in Figure 2.

Particle 1 flows to position 2 (write a Chinese character in simplified form do 1～2, as follows) from the position, and 1～2 time is t ₁, 2～3 time is t ₂, 3～4 time is t ₃By:

t ₁＝t ₃＝dw (1)

t ₂＝(w-d)v (2)

Wherein: d particle diameter, w are CCD pixel height, the v water velocity.Can solve:

d＝t ₁w/(t ₁+t ₂)(3)

For reducing the error that t1 brings, use t simultaneously ₁And t ₃Two parameters, particle diameter can be written as:

$d=\frac{({\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="H2007100387372E00012.png,H2007100387372E00021.png"\; state="\{\{state\}\}">t</figure-callout>}}_1+t_3)w}{{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="H2007100387372E00012.png,H2007100387372E00021.png"\; state="\{\{state\}\}">t</figure-callout>}}_1+{\mathrm{<figure-callout\; id="3"\; label="t"\; filenames="H2007100387372E00012.png,H2007100387372E00013.png"\; state="\{\{state\}\}">t</figure-callout>}}_3+2t_2}---\left(4\right)$

Be that particle diameter d can pass through w, t ₁, t ₂, t ₃Calculate, and do not rely on light intensity numerical value, and also irrelevant with water velocity v.

(2) particle diameter is less than the height of CCD pixel, and two adjacent image point light intensity of affected, as shown in Figure 3, light intensity signal and the last a kind of situation of this moment are similar, only need the light intensity decreasing signal of two pixels is superposeed the back as a signal, the method above using is calculated and is got final product.

(3) particle diameter is greater than the height of CCD pixel, and two or three pixel light intensity of affected.As shown in Figure 4, this moment, particle from time of 1～3 (through 2) was:

t＝t ₁+t ₂+t ₃＝(w+d)/v (5)

With two or three pixel light intensity decreasing signals stack back as a signal, at known t, w, under the situation of v (so the time t ₁, t ₂The detection resolution of separation is relatively poor, so use total time t), can calculate particle diameter d:

d＝tv-w (6)

According to the foregoing invention design, the present invention adopts following technical proposals:

A kind of tiny particle in water On-line Measuring Method comprises the detected water sample pipeline of flowing through, and adopts grain size and quantity in the light blockage method on-line measurement water, it is characterized in that described pipeline adopts flat tube, and the center section of this pipeline is as sampling window; The light source that described light blockage method adopts is the sheet directional light, and the optical receiver of employing is the line array CCD device.

The height of above-mentioned sampling window is the height of each pixel of line array CCD device, is 10～20 μ m, and length is the length of 300～500 pixels of CCD, is 3～10mm, and thickness is the thickness of flat tube, is 0.5 ± 0.1mm.

Above-mentioned particle diameter is less than the height of CCD pixel, and particle only influences a pixel light intensity, is calculated as follows particle diameter by the DSP of measuring system (digital signal processor, below identical):

$d=\frac{({\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="H2007100387372E00012.png,H2007100387372E00021.png"\; state="\{\{state\}\}">t</figure-callout>}}_1+t_3)w}{{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="H2007100387372E00012.png,H2007100387372E00021.png"\; state="\{\{state\}\}">t</figure-callout>}}_1+{\mathrm{<figure-callout\; id="3"\; label="t"\; filenames="H2007100387372E00012.png,H2007100387372E00013.png"\; state="\{\{state\}\}">t</figure-callout>}}_3+2{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="H2007100387372E00012.png,H2007100387372E00013.png"\; state="\{\{state\}\}">t</figure-callout>}}_2}$

Wherein, w is a CCD pixel height, t ₁For particle enters time of pixel area, t ₂For particle at the time that pixel area flows, t ₃Flow out the time of pixel area for particle.

Above-mentioned particle diameter is less than the height of CCD pixel, and two adjacent image point light intensity of affected, and is by the DSP of measuring system that the light intensity decreasing signal stack of two pixels is back as a signal, is calculated as follows particle diameter:

$d=\frac{({\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="H2007100387372E00012.png,H2007100387372E00021.png"\; state="\{\{state\}\}">t</figure-callout>}}_1+t_3)w}{{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="H2007100387372E00012.png,H2007100387372E00021.png"\; state="\{\{state\}\}">t</figure-callout>}}_1+{\mathrm{<figure-callout\; id="3"\; label="t"\; filenames="H2007100387372E00012.png,H2007100387372E00013.png"\; state="\{\{state\}\}">t</figure-callout>}}_3+2{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="H2007100387372E00012.png,H2007100387372E00013.png"\; state="\{\{state\}\}">t</figure-callout>}}_2}$

Wherein, w is a CCD pixel height, t ₁For particle enters time of pixel area, t ₂For particle at the time that pixel area flows, t ₃Flow out the time of pixel area for particle.

Above-mentioned particle diameter is greater than the height of CCD pixel, and two or three adjacent image point light intensity of affected, and is by the DSP of measuring system that the light intensity decreasing signal stack of two or three pixels is back as a signal, is calculated as follows particle diameter:

d＝tv-w

Wherein, w is a CCD pixel height; T=t ₁+ t ₂+ t ₃Be T.T., promptly begin to enter pixel area to the time of leaving pixel area fully from particle; V is a water velocity.

A kind of tiny particle in water on-line measurement device is used for above-mentioned On-line Measuring Method, comprises the DSP of pipeline, light source, light receiving element and a measuring system of aqueous sample stream warp, it is characterized in that:

1) described pipeline is a flat tube, and the center section of this pipeline is as sampling window;

2) described light source is the described sampling window of sheet directional light perpendicular alignmnet;

3) described light receiving element is aimed at the sampling window fixed installation for the line array CCD device;

4) described line array CCD device connects the DSP of measuring system by RS485 interface connection main frame.

The height of above-mentioned sampling window is the height of each pixel of line array CCD device, is 10～20 μ m, and length is the length of 300～500 pixels of CCD, is 3～10mm, and thickness is the thickness of flat tube, is 0.5 ± 0.1mm.

The generation mechanism of above-mentioned sheet directional light is: settle one group of post lens combination on the semiconductor laser emitted laser beam path.

A throttling valve is installed at the water delivering orifice place of above-mentioned pipeline.

The present invention compared with prior art, have following conspicuous outstanding substantive distinguishing features and remarkable advantage: (1) the present invention adopts flat tube and line array CCD device, has solved common light blockage method tubule obstructing problem.(2) reduce the area of light receiving element greatly, make it can be comparable, improved signal to noise ratio (S/N ratio) with the particulate area.(3) water velocity is not high, and the linear array light receiving element carries out high-speed sampling, has improved the accuracy of measuring.

Description of drawings:

Fig. 1 is the structure principle chart that On-line Measuring Method of the present invention adopts.

Fig. 2 synoptic diagram that to be particle diameter only influence a pixel light intensity less than the height and the particle of CCD pixel, wherein (a) figure is the particle flow synoptic diagram, (b) figure is the light intensity synoptic diagram that receives.

Fig. 3 is that particle diameter is less than the height of CCD pixel and the synoptic diagram of two adjacent image point light intensity of affected.

Fig. 4 be particle diameter greater than the height of CCD pixel and the synoptic diagram of two or three adjacent image point light intensity of affected, wherein (a) figure is the particle flow synoptic diagram, (b) figure is the light intensity synoptic diagram that receives.

Fig. 5 is the structural representation of an on-line measurement device embodiment of the present invention.Wherein (a) figure is a vertical view, and (b) figure is a front view.

Embodiment

A preferential embodiment accompanying drawings of the present invention is as follows:

This tiny particle in water On-line Measuring Method adopts on-line measurement device shown in Figure 5 to measure, and the structure and the measuring method of device are as follows:

The laser that is sent by semiconductor laser (1) forms sheet directional light (4) through post lens combination (2) (3), by light hurdle (5), after passing sampling window (6), photosensitive part (8) by line array CCD (7) is accepted, after the system handles of dsp chip and a small amount of peripheral components (9) composition, by serial port output measurement result.Line array CCD (7), dsp chip and a small amount of peripheral components (9) all are installed on the circuit board (10), make connecting line the shortest, to reduce interference and noise.Measured water sample flows into from water inlet (11), through rectangle sampling window (6), behind the throttling valve (12), is flowed out by water delivering orifice (13).The speed of current is regulated by throttling valve (12).

This measuring method allows a plurality of particulates to pass through sampling window simultaneously, but does not allow particulate overlapping in sample plane.In fact, because of tested be high-purity water mostly, the particle number in the water sample is seldom, two particulates have been very little through the probability of sampling window simultaneously, and the thickness of sampling window is very little, two particulates overlapping probability in sampling window is very little.

Line array CCD uses TCD1209D, 2048 points, every 14 * 14 μ m, maximum clock frequency 20MHz.Because of not needing much more so counting, simultaneously also in order to improve acquisition speed, actually only used 350 points of front, formed the sampling window that width is about 4.9mm.DSP uses TMS320LF2812, and sheet includes the A/D of 12 80ns.Measuring system is used the 10MHz sampling, and gathering 350 spot speed is 28.5KHz, and promptly per 35 μ S gather the light intensity data of one group of CCD.When the water velocity of sampling window was 3mm/S, sampling resolution was about 0.1 μ m, has satisfied the requirement of Measurement Resolution, if can use the chip of 20MHz sample rate, then resolution also can double, or under identical resolution, water velocity can double.

By regulating throttling valve, the water velocity of sampling window is controlled at 3mm/S, when in the water sample of the sampling window of flowing through particulate being arranged, line array CCD, the light intensity that receives can change, when only having a CCD pixel light intensity to change, use the light intensity signal of a CCD pixel, when two or more adjacent CCD pixel light intensity change, with their signal stack, first use formula (6) is calculated mean particle dia, as the result of calculation mean particle dia less than 0.8w, then use formula (4) to calculate mean particle dia again, to improve measuring accuracy.Measurement result sends to main frame with the form of numeral by the RS485 interface.Finish functions such as demonstration, record, printing by main frame.

Claims (4)

1. tiny particle in water On-line Measuring Method comprises the detected water sample pipeline of flowing through, and adopts grain size and quantity in the light blockage method on-line measurement water, it is characterized in that described pipeline adopts flat tube, and the center section of this pipeline is as sampling window (6); The light source that described light blockage method adopts is the sheet directional light, and the optical receiver of employing is line array CCD device (7); The height of described sampling window (6) is the height of each pixel of line array CCD device (7), is 10～20 μ m, and length is the length of 300～500 pixels of CCD, is 3～10mm, and thickness is the thickness of flat tube, is 0.5 ± 0.1mm; The concrete steps of this method are:

A. when particle diameter during less than the height of CCD pixel, and particle only influences a pixel light intensity, is calculated as follows particle diameter by the DSP of measuring system:

$d=\frac{(t_1+t_3)w}{t_1+t_3+2t_2}$

Wherein, w is a CCD pixel height, t ₁For particle enters time of pixel area, t ₂Be the time that particle flows, t in pixel area ₃Flow out the time of pixel area for particle;

B. when particle diameter during, and two adjacent image point light intensity of affected less than the height of CCD pixel, by the DSP of measuring system with the light intensity decreasing signal stack back of two pixels as a signal, be calculated as follows particle diameter:

$d=\frac{(t_1+t_3)w}{t_1+t_3+2t_2}$

Wherein, w is a CCD pixel height, t ₁For particle enters time of pixel area, t ₂Be the time that particle flows, t in pixel area ₃Flow out the time of pixel area for particle.

C. when particle diameter during, and two or three adjacent image point light intensity of affected greater than the height of CCD pixel, by the DSP of measuring system with the light intensity decreasing signal stack back of two or three pixels as a signal, be calculated as follows particle diameter:

d＝tv-w

T=t wherein ₁+ t ₂T+t ₃Be T.T., promptly begin to enter pixel area to the time of leaving pixel area fully from particle; V is a water velocity.

2. a tiny particle in water on-line measurement device is used for the described tiny particle in water On-line Measuring Method of claim 1, comprises the DSP of pipeline, light source, light receiving element and a measuring system of aqueous sample stream warp, it is characterized in that:

1) described pipeline is a flat tube, and the center section of this pipeline is as sampling window (6);

2) described light source is sheet directional light (4), the described sampling window of its perpendicular alignmnet (6);

3) described light receiving element is that line array CCD device (7) is aimed at sampling window (6) fixed installation;

4) described line array CCD device (7) connects the DSP (9) of measuring system by RS485 interface connection main frame;

The height of sampling window (6) is the height of each pixel of line array CCD device (7), is 10～20 μ m, and length is the length of 300～500 pixels of CCD, is 3～10mm, and thickness is the thickness of flat tube, is 0.5 ± 0.1mm.

3. tiny particle in water on-line measurement device according to claim 2 is characterized in that the generation mechanism of described sheet directional light (4) is: settle one group of post lens combination (2,3) on a semiconductor laser (1) the emitted laser beam path.

4. tiny particle in water on-line measurement device according to claim 2 is characterized in that the water delivering orifice (13) of described pipeline locates to install a throttling valve (12).

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