CN113406040A - Novel method and device for measuring turbidity and total organic carbon on line at high precision - Google Patents
Novel method and device for measuring turbidity and total organic carbon on line at high precision Download PDFInfo
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
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Abstract
The invention provides a novel method and a novel device for measuring turbidity and total organic carbon on line at high precision. The device comprises a laser light source module, a water path module, a light path turning-back module, a detector module and a data inversion module. Wherein, the waterway module comprises a cuvette; the light path turning back module comprises a first reflecting prism, a second reflecting prism, a reflecting cover and a quartz lens; the detector module includes a first photodetector and a second photodetector. The invention adopts the laser beam emitted by the laser light source module to detect the sample water, so that the light intensity and the spectral characteristic are stable, the influence of the test environment is avoided, the sensitivity of water quality parameter measurement can be effectively improved, and the laser light source module, the first reflecting prism, the cuvette, the reflecting cover, the second reflecting prism and the quartz lens are sequentially distributed along the light path, so that the laser beam can be turned back for multiple times according to the preset light path, the effective length of the light beam and the sample water is increased, the lower limit of the measurement threshold value is reduced, and the sensitivity of water quality parameter measurement is improved.
Description
Technical Field
The invention relates to the technical field of water quality detection, in particular to a novel method and a novel device for measuring turbidity and total organic carbon on line at high precision.
Background
Water plays a vital role in industry, agriculture and even daily life of people, and with the improvement of living standard, people have higher and higher requirements on water quality turbidity measurement, but because of various artificial pollution and natural factors, the water quality is changed, and the quality of the water quality determines whether a water source can be utilized or not. Turbidity is an important index for evaluating water quality, is one of the simplest methods for judging whether a water source is polluted or not, and is an important means in the aspects of drinking water safety and water body pollution monitoring. Therefore, accurate determination of water quality turbidity is particularly important for water quality evaluation, and the online monitoring with simple operation, high sensitivity and low threshold value is the development direction of the method.
Most turbidity measuring devices at present have the problems of low measuring precision, poor sensitivity and easy introduction of secondary pollution, and simultaneously, a sample can not detect various parameters simultaneously.
The total organic carbon is one of important water quality indexes reflecting that water quality is polluted by organic matters, means that the total carbon content of soluble and suspended organic matters in water is used as an organic matter comprehensive index, can represent organic pollution degree more than BOD (Biochemical Oxygen Demand) and COD (Chemical Oxygen Demand), and is a characteristic index of various pollution events, for example: red tide, domestic polluted water and chemical industrial sewage. The total organic carbon is a newly developed water environment organic matter pollution evaluation index in recent years, and is widely applied to water supply of rivers, lakes, oceans and living, and water quality monitoring of petrochemical industry, power generation and metallurgy industries at present.
The current methods for measuring the total organic carbon include a differential method, an NPOC (non-purgable organic carbon) method, a spectrum method and an ultraviolet light intensity method. The subtraction method and the NPOC method do not have real-time performance, samples need to be sampled to a laboratory or detection needs to be completed through large-scale equipment, and the spectrum method is easily influenced by other substances, so that the analysis result is influenced.
Disclosure of Invention
The invention aims to provide a novel method and a novel device for measuring turbidity and total organic carbon on line at high precision, which can improve the measurement precision and sensitivity of water quality parameters, realize real-time on-line detection of the water quality parameters, are not easily influenced by other substances, have strong anti-interference performance, can detect various water quality parameters of the water quality turbidity and the total organic carbon at one time and improve the detection efficiency.
In order to solve the above technical problems, a first aspect of the present invention provides a novel apparatus for online high-precision measurement of turbidity and total organic carbon, comprising: the system comprises a laser light source module 10, a water path module 20, a light path foldback module 30, a detector module 40 and a data inversion module 50; the waterway module 20 includes a cuvette 21; the optical path turning back module 30 comprises a first reflecting prism 31, a second reflecting prism 32, a reflecting shade 33 and a quartz lens 34; the detector module 40 includes a first photodetector 41 and a second photodetector 42; the data inversion module 50 is respectively connected with the first photodetector 41 and the second photodetector 42 in a communication manner;
wherein, the cuvette 21 is filled with sample water; the laser light source module 10, the first reflecting prism 31, the cuvette 21, the reflecting shade 33, the second reflecting prism 32 and the quartz lens 34 are sequentially arranged along a light path, a laser beam emitted by the laser light source module 10 is reflected to the sample water through the first reflecting prism 31, the laser beam transmitted by the sample water is sequentially transmitted to the second photoelectric detector 42 through the reflection of the second reflecting prism 32, the re-transmission of the sample water and the reflection of the first reflecting prism 31, and the laser beam scattered by the sample water is sequentially transmitted to the first photoelectric detector 41 through the reflection of the reflecting shade 33 and the convergence of the quartz lens 34.
Optionally, the laser light source module 10 includes a light source, a beam combining mirror 11 and a shaping lens group 12 that are sequentially arranged along a light path, the light source outputs laser beams with at least two different wavelengths, the beam combining mirror 11 combines the laser beams with different wavelengths output by the light source and outputs the combined laser beams to the shaping lens group 12, and the shaping lens group 12 collimates the laser beams output by the beam combining mirror 11.
Optionally, the first reflection prism 31 is a right-angle prism, and both side surfaces of the first reflection prism 31 forming a right angle are plated with broadband reflection films.
Optionally, the second reflecting prism 32 and the first reflecting prism 31 are the same in size, shape and material.
Optionally, the cuvette 21 is cylindrical and is made of quartz material, and a ratio of a height of the cuvette 21 to a cross-sectional diameter of the cuvette is greater than 4.
Optionally, the height of reflector 33 with the height of cell 21 equals, and 360 covers and establishes on the cell 21 top surface, in order to encircle cell 21 sets up, the top of reflector 33 is equipped with one just right the opening of cell 21, the laser beam of sample water transmission follows the opening directly arrives on the second reflection prism 32.
Optionally, the bottom of reflector 33 is opened completely, and the opening diameter of the bottom of reflector 33 equals at least 4 times the height of cell 21, the opening on the top of reflector 33 with the tangential direction of the position that the cell 21 lateral wall meets is 25 ~ 40 for the contained angle scope of horizontal direction, the tangential direction of the border position of the bottom of reflector 33 is 50 ~ 65 for the contained angle scope of horizontal direction.
Optionally, the waterway module 20 further includes a water supply and drainage unit 22, a water inlet and an overflow port are respectively formed at the upper end and the lower end of the side wall of the cuvette 21, and the water supply and drainage unit 22 is communicated with the water inlet and the overflow port to charge and drain the cuvette 21.
Optionally, the water supply and drainage unit 22 includes a micro-flow pump 221, a first flow folding device 222, a drainage pump 223, a second flow folding device 224, and a water level detection device 225; the first baffle device 222 is arranged between the cuvette 21 and the micro-flow pump 221, and a water inlet of the cuvette 21 is connected with the first baffle device 222 and the drain pump 223 respectively; the overflow port of the cuvette 21 is connected to the water level detection device 225 through the second baffle 224.
Optionally, central axes of the cuvette 21, the first reflecting prism 31, the second reflecting prism 32, the reflector 33 and the quartz lens 34 coincide.
Based on the novel device for measuring turbidity and total organic carbon on line with high precision, the second aspect of the invention also provides a novel method for measuring turbidity and total organic carbon on line with high precision, which comprises the following steps:
s1, providing a laser beam for high-precision turbidity and total organic carbon measurement by the laser light source module;
s2, providing sample water by the waterway module, and carrying out sample treatment on the sample water;
s3, the light path turning-back module turns back the laser beam according to a preset light path, so that the laser beam passes through the sample water, and a scattered light signal and a transmitted light signal passing through the sample water are obtained;
s4, the detector module performs photoelectric conversion processing on the scattered light signals and the transmitted light signals to obtain electric signals respectively corresponding to the scattered light signals and the transmitted light signals;
and S5, the data inversion module performs inversion according to the electric signals to obtain the turbidity value and the total organic carbon value of the sample water.
Optionally, the laser beam in S1 includes one of a first wavelength beam, a second wavelength beam and a third wavelength beam, or a combined beam obtained by combining at least two of the first wavelength beam, the second wavelength beam and the third wavelength beam.
Optionally, before the measuring of the water turbidity and the total organic carbon of the sample water, when the laser beam is a combined beam obtained by combining the first wavelength beam and the second wavelength beam, the method further includes:
s6, loading a plurality of first standard solutions with different concentrations in the cuvette, respectively carrying out a plurality of groups of experimental calibrations to obtain a voltage value corresponding to the concentration of each first standard solution, and carrying out data fitting by the data inversion module according to the concentration of each first standard solution and the voltage value corresponding to the concentration of each first standard solution to obtain a weighted numerical value d1 of a first wavelength light beam in the scattered light signal and a weighted numerical value d2 of the first wavelength light beam in the transmitted light signal so as to obtain a first calibration relational expression for measuring the water turbidity of the sample water by the first wavelength light beam;
s7, when the cuvette is in a cavity state, the second photodetector performs photoelectric conversion on the second wavelength light beam in the transmitted light signal to obtain a first voltage value U1 corresponding to the second wavelength light beam;
s8, loading a plurality of second standard solutions with different concentrations in the cuvette, respectively carrying out a plurality of groups of experimental calibration to obtain a voltage value corresponding to the concentration of each second standard solution, and carrying out data fitting by the data inversion module according to the concentration of each second standard solution, the voltage value corresponding to the concentration of each second standard solution and the first voltage value U1 to obtain a second calibration relational expression for measuring the total organic carbon value of the water quality of the sample through the second wavelength light beam.
Optionally, the first calibration relation is as follows:
T＝U2/(d1*U2+d2*U3)
wherein T is the turbidity value of the sample water, U2 is a second voltage value obtained by photoelectric conversion of the first wavelength light beam in the scattered light signal, U3 is a third voltage value obtained by photoelectric conversion of the first wavelength light beam in the transmitted light signal, and d2 is the weighted value of the first wavelength light beam in the scattered light signal; d3 is the weighted value of the first wavelength beam in the transmitted light signal.
Optionally, when the laser beam is a combined beam obtained by combining the first wavelength beam and the second wavelength beam, and the cuvette is loaded with the sample water, the S4 includes:
s4.1, performing photoelectric conversion on the first wavelength light beam in the scattered light signal by the first photoelectric detector to obtain a second voltage value U2 corresponding to the first wavelength light beam;
s4.2, the second photoelectric detector respectively carries out photoelectric conversion on the first wavelength light beam and the second wavelength light beam in the transmitted light signal to obtain a third voltage value U3 corresponding to the first wavelength light beam and a fourth voltage value U4 corresponding to the second wavelength light beam.
Optionally, the S5 includes:
s5.1, the data inversion module performs inversion to obtain the turbidity value of the sample water according to the second voltage value U2, the third voltage value U3 and the first calibration relation;
and S5.2, the data inversion module performs inversion according to the fourth voltage value U4 and the second calibration relational expression to obtain the total organic carbon value of the sample water.
Compared with the prior art, the technical scheme provided by the invention has at least one of the following beneficial effects:
in the novel method and the device for measuring turbidity and total organic carbon on line at high precision, the sample water is detected by the laser beam emitted by the laser light source module, so that the light intensity and the spectral characteristic are stable, the influence of the test environment is avoided, the sensitivity and the anti-interference performance of water quality parameter measurement can be effectively improved, and the laser light source module, the first reflecting prism, the cuvette, the reflecting cover, the second reflecting prism and the quartz lens are sequentially arranged along the light path, so that the laser beam can be turned back for multiple times according to the preset light path, the effective length of the light beam and the water sample to be measured can be increased, the lower limit of a measurement threshold value is further reduced, and the sensitivity of the water quality parameter measurement is improved.
Furthermore, in the novel online high-precision method and device for measuring turbidity and total organic carbon provided by the invention, the collected scattered light signals at different angles can be automatically weighted through the reflector, so that the measuring range of water turbidity is expanded, the precision of water quality measurement is improved, the influence of light intensity on a measuring result can be completely eliminated through the two photoelectric detectors and the data inversion module, and the measuring device and the measuring method can also be used for detecting various water quality parameters of water turbidity and total organic carbon at one time, so that the detection efficiency is effectively improved, and the time cost is saved.
Drawings
Fig. 1 is a block diagram of a novel apparatus for online high-precision measurement of turbidity and total organic carbon provided in this embodiment;
fig. 2 is a schematic view of an optical path system of a novel device for online high-precision measurement of turbidity and total organic carbon provided in this embodiment;
fig. 3 is a flowchart of a novel method for online high-precision measurement of turbidity and total organic carbon according to this embodiment.
Detailed Description
As mentioned in the background of the invention, water plays a vital role in industry, agriculture and even daily life of people, and with the improvement of living standard, people have higher and higher requirements for measuring the turbidity of water quality, but due to various artificial pollution and natural factors, the water quality is changed, and the quality of the water quality determines whether the water source can be utilized or not. Turbidity is an important index for evaluating water quality, is one of the simplest methods for judging whether a water source is polluted or not, and is an important means in the aspects of drinking water safety and water body pollution monitoring. Therefore, accurate determination of water quality turbidity is particularly important for water quality evaluation, and the online monitoring with simple operation, high sensitivity and low threshold value is the development direction of the method. The total organic carbon is one of important water quality indexes reflecting that water quality is polluted by organic matters, means that the total carbon content of soluble and suspended organic matters in water is used as an organic matter comprehensive index, can represent the organic pollution degree more than BOD and COD, and is a characteristic index of various pollution events, such as: red tide, domestic polluted water and chemical industrial sewage. The total organic carbon is a newly developed water environment organic matter pollution evaluation index in recent years, and is widely applied to water supply of rivers, lakes, oceans and living, and water quality monitoring of petrochemical industry, power generation and metallurgy industries at present.
At present, most turbidity measuring devices have the problems of low measuring precision, poor sensitivity and easy introduction of secondary pollution, and simultaneously, a primary sample cannot simultaneously detect various parameters. In addition, methods for measuring the total organic carbon include a differential method, an NPOC method, a spectroscopic method, and an ultraviolet light intensity method. The subtraction method and the NPOC method do not have real-time performance, samples need to be sampled to a laboratory or detection needs to be completed through large-scale equipment, and the spectrum method is easily influenced by other substances, so that the analysis result is influenced.
Therefore, the invention provides a novel method and a novel device for measuring turbidity and total organic carbon on line with high precision, which can improve the measurement precision and sensitivity of water quality parameters, can realize real-time on-line detection of the water quality parameters, are not easily influenced by other substances, have strong anti-interference performance, can detect various water quality parameters of water quality turbidity and total organic carbon at one time and improve the detection efficiency.
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.
The embodiment provides a novel method and a novel device for measuring turbidity and total organic carbon on line at high precision. The novel on-line high-precision method and apparatus for measuring turbidity and total organic carbon according to this embodiment will be described with reference to FIGS. 1-3.
Referring to fig. 1, the present embodiment provides a novel online device 1 for measuring turbidity and total organic carbon with high precision, which includes: the system comprises a laser light source module 10, a water path module 20, a light path retracing module 30, a detector module 40 and a data inversion module 50. Referring to fig. 2, the waterway module 20 includes a cuvette 21; the optical path turning back module 30 comprises a first reflecting prism 31, a second reflecting prism 32, a reflecting shade 33 and a quartz lens 34; the detector module 40 includes a first photodetector 41 and a second photodetector 42; the data inversion module 50 is communicatively coupled to the first photodetector 41 and the second photodetector 42, respectively.
Wherein, the cuvette 21 is filled with sample water; the laser light source module 10, the first reflecting prism 31, the cuvette 21, the reflecting shade 33, the second reflecting prism 32 and the quartz lens 34 are sequentially arranged along a light path, a laser beam emitted by the laser light source module 10 is reflected to the sample water through the first reflecting prism 31, the laser beam transmitted by the sample water is sequentially transmitted to the second photoelectric detector 42 through the reflection of the second reflecting prism 32, the re-transmission of the sample water and the reflection of the first reflecting prism 31, and the laser beam scattered by the sample water is sequentially transmitted to the first photoelectric detector 41 through the reflection of the reflecting shade 33 and the convergence of the quartz lens 34.
The center axes of the cuvette 21, the first reflecting prism 31, the second reflecting prism 32, the reflector 33, and the quartz lens 34 in this embodiment coincide with each other.
It is understood that in this embodiment, the first photodetector 41 is disposed at a focal position of the quartz lens 34 for receiving the laser beam scattered by the sample water, and the second photodetector 42 is disposed on a reflection path of the first reflection prism 31 for reflecting the laser beam transmitted by the sample water for the second time, for receiving the laser beam transmitted by the sample water. The first photodetector 41 and the second photodetector 42 respectively perform photoelectric conversion on the scattered light signals and the transmitted light signals respectively corresponding to the laser beams scattered by the sample water and the transmitted laser beams to obtain electric signals respectively corresponding to the scattered light signals and the transmitted light signals, and then the turbidity value and the total organic carbon value of the sample water are obtained through inversion by the data inversion module 50 according to the electric signals.
Referring to fig. 2, the laser light source module 10 includes a laser light source emitting port, and the laser light source emitting port faces an outer wall of a right-angle side surface of the first reflection prism 31; the laser beam emitted from the laser source emitting port is turned back for multiple times by the light path turning-back module 30 to obtain a first reflection path a, a second reflection path b, a third reflection path c and a fourth reflection path d.
The first reflection prism 31 is a right-angle prism, and both side surfaces of the first reflection prism 31 forming a right angle are plated with broadband reflection films. The first reflection prism 31 reflects the laser beam emitted by the laser source module 10 to obtain a first reflection path a. The inner wall of one right-angled side surface of the second reflection prism 32 reflects the laser beam on the first reflection path a to obtain the second reflection path b, the laser beam on the second reflection path b reflects the laser beam on the inner wall of the other right-angled side surface of the second reflection prism 32 to obtain the third reflection path c, and the laser beam on the third reflection path c reflects the laser beam on the outer wall of the other right-angled side surface of the first reflection prism 31 to obtain the fourth reflection path d.
In this embodiment, the second reflecting prism 32 and the first reflecting prism 31 are the same in size, shape and material. The first reflection prism 31 and the second reflection prism 32 in this embodiment are used to reflect the laser beam multiple times, so that the laser beam passes through the sample water multiple times, and the intensity of the scattered light obtained after the laser beam passes through the sample water is enhanced.
It should be noted that the laser light source module 10 includes a light source, a beam combining mirror 11 and a shaping lens group 12 which are sequentially arranged along a light path, the light source outputs at least two laser beams with different wavelengths, the beam combining mirror 11 combines the laser beams with different wavelengths output by the light source and outputs the combined laser beams to the shaping lens group 12, and the shaping lens group 12 collimates the laser beams output by the beam combining mirror 11.
The laser beam in this embodiment may include an ultraviolet laser, a near-infrared laser, and a blue laser, the multiple lasers may be collimated and combined in the laser source module 10, and the paths of the multiple lasers after combination are the same. In this embodiment, the wavelengths of the laser beams output by the laser light source module 10 may be 850nm, 650nm and 275nm, and the light sources in the three bands may be used alone or in combination, and when used in combination, the beam combining mirror 11 may be used to perform beam combining output.
In this embodiment, the cuvette 21 is cylindrical and is made of a quartz material, and the ratio of the height of the cuvette 21 to the cross-sectional diameter thereof is greater than 4. The cuvette 21 in this embodiment is a cylindrical hollow cuvette for holding sample water or a calibration solution. The cuvette 21 is made of quartz material, which has a better transmittance for the laser beam passing through the cuvette 21.
The height of reflector 33 with the height of cell 21 equals, and 360 covers and establish on the cell 21 top surface, in order to encircle cell 21 sets up, the top of reflector 33 is equipped with one just right the opening of cell 21, the laser beam of sample water transmission is followed the opening directly arrives on the second reflection prism 32. The bottom of reflector 33 is opened completely, and the opening diameter of the bottom of reflector 33 equals at least 4 times the height of cell 21, the opening on the top of reflector 33 with the tangential direction of the position that the cell 21 lateral wall meets is 25 ~ 40 for the contained angle scope of horizontal direction, the tangential direction of the border position of the bottom of reflector 33 is 50 ~ 65 for the contained angle scope of horizontal direction.
Alternatively, the top opening of the reflector 33 in this embodiment may be circular, and the size of the opening may be slightly larger than the cross-sectional diameter of the cuvette 21 so as to match the cross-sectional area of the cuvette 21. The absolute value of the slope of the curved surface of the reflector 33 at half the height is 1, and the included angle of the tangent line of the curved surface at the position is 45 degrees. When the laser beam passes through the sample water, the laser beam can scatter light rays in different directions 360 degrees around the central axis of the reflector 33 or the cuvette 21 on the path passing through the sample water, and the light rays are reflected and collected by the reflector 33 and enter the quartz lens 34. The design of the reflector 33 influences the collection of scattered light in different directions, that is, the scattered light in different directions is weighted under the action of the reflector 33, so that the parameter range of online measurement can be enlarged, and the linearity of data fitting can be calibrated.
When the water quality is detected on line in real time, the waterway module 20 further includes a water supply and drainage unit 22, a water inlet and an overflow port are respectively formed on the upper end and the lower end of the side wall of the cuvette 21, and the water supply and drainage unit 22 is communicated with the water inlet and the overflow port to charge and drain the cuvette 21.
The water supply and drainage unit 22 comprises a micro-flow pump 221, a first flow folding device 222, a drainage pump 223, a second flow folding device 224 and a water level detection device 225; the first baffle device 222 is arranged between the cuvette 21 and the micro-flow pump 221, and a water inlet of the cuvette 21 is connected with the first baffle device 222 and the drain pump 223 respectively; the overflow port of the cuvette 21 is connected to the water level detection device 225 through the second baffle 224.
Specifically, the micro flow pump 221 is configured to extract sample water of a water source to be detected in real time, and the first baffling device 222 performs bubble removal processing on the extracted sample water, and then conveys the sample water after bubble removal processing to the cuvette 21. When the sample water overflows from the upper portion of the cuvette 21, the overflowed sample water is deaerated by the second baffle 224 and then transferred to the water level detecting unit 225. And if the water level detection device 225 detects that the water level of the overflowed sample water reaches a preset threshold value, triggering the micro-flow pump 221 to stop working. Optionally, after the detection is completed, the sample water or the solution for calibration of the test loaded in the cuvette 21 can be drained by the drain pump 223 connected to the water inlet.
Further, based on the above-mentioned novel online high-precision turbidity and total organic carbon measuring device, the present invention also provides a novel online high-precision turbidity and total organic carbon measuring method, which is shown in fig. 3 and comprises the following steps:
s1, providing a laser beam for high-precision turbidity and total organic carbon measurement by the laser light source module;
s2, providing sample water by the waterway module, and carrying out sample treatment on the sample water;
s3, the light path turning-back module turns back the laser beam according to a preset light path, so that the laser beam passes through the sample water, and a scattered light signal and a transmitted light signal passing through the sample water are obtained;
s4, the detector module performs photoelectric conversion processing on the scattered light signals and the transmitted light signals to obtain electric signals respectively corresponding to the scattered light signals and the transmitted light signals;
and S5, the data inversion module performs inversion according to the electric signals to obtain the turbidity value and the total organic carbon value of the sample water.
In the novel method for measuring turbidity and total organic carbon on line at high precision, the sample water is detected by the laser beam emitted by the laser light source module, so that the light intensity and the spectral characteristic are stable, the influence of the test environment is avoided, the sensitivity and the anti-interference performance of water quality parameter measurement can be effectively improved, and the laser light source module, the first reflecting prism, the cuvette, the reflecting cover, the second reflecting prism and the quartz lens are sequentially arranged along the light path, so that the laser beam can be turned back for multiple times according to the preset light path, the effective length of the light beam and the water sample to be measured can be increased, the lower limit of the measurement threshold value is further reduced, and the sensitivity of the water quality parameter measurement is improved.
In step S1, the laser light source module may provide a laser beam for high precision turbidity and total organic carbon measurements. The laser beam in S1 may include one of a first wavelength beam, a second wavelength beam and a third wavelength beam, or a combined beam obtained by combining at least two of the first wavelength beam, the second wavelength beam and the third wavelength beam. That is, the laser beam may be a single laser beam or a combined beam obtained by combining at least two laser beams.
Optionally, before the measuring of the water turbidity and the total organic carbon of the sample water, when the laser beam is a combined beam obtained by combining the first wavelength beam and the second wavelength beam, the method further includes:
s6, a plurality of first standard solutions with different concentrations are loaded in the cuvette, a plurality of groups of experimental calibrations are respectively carried out to obtain a voltage value corresponding to the concentration of each first standard solution, and the data inversion module carries out data fitting according to the concentration of each first standard solution and the voltage value corresponding to the concentration of each first standard solution to obtain a weighted numerical value d1 of a first wavelength light beam in the scattered light signal and a weighted numerical value d2 of the first wavelength light beam in the transmitted light signal, so as to obtain a first calibration relational expression for measuring the water quality turbidity of the sample water through the first wavelength light beam.
Of course, before the cuvette 21 is loaded with the calibration solution, the method further comprises:
s7, when the cuvette is in the cavity state, the second photodetector performs photoelectric conversion on the second wavelength light beam in the transmitted light signal to obtain a first voltage value U1 corresponding to the second wavelength light beam.
Specifically, the first wavelength beam may be a 650nm laser beam, and the second wavelength beam may be a 275nm laser beam. In this embodiment, the 650nm laser beam is used for measuring the turbidity of water, and the 275nm laser beam is used for measuring the total organic carbon value of water.
Before the turbidity of water is measured, the first calibration relation is calibrated. The first calibration relation is as follows:
T＝U2/(d1*U2+d2*U3)
wherein T is a turbidity value of the sample water, U2 is a second voltage value obtained by photoelectric conversion of a first wavelength beam, i.e., a 650nm laser beam, in the scattered light signal, U3 is a third voltage value obtained by photoelectric conversion of a first wavelength beam, i.e., a 650nm laser beam, in the transmitted light signal, and d2 is a weighted value of the first wavelength beam in the scattered light signal; d3 is the weighted value of the first wavelength beam in the transmitted light signal.
In this embodiment, to obtain the first calibration relation, the d1 value and the d2 value in the first calibration relation are obtained. For this purpose, the cuvette 21 may be loaded with a formalin solution for calibration in a first calibration relation for measuring the turbidity of the water. When the cuvette 21 was filled with a formalin solution having a concentration of T1, the laser light source module emitted a combined beam obtained by combining a laser beam of 650nm and a laser beam of 275 nm. The first photodetector receives the scattered laser beam and converts a laser signal of 650nm wavelength in the scattered laser beam into a voltage signal U21, and then the second photodetector receives the transmitted laser beam and converts a laser signal of 650nm wavelength in the transmitted laser beam into a voltage signal U31.
Wherein, U21 ═ K21 ═ I21, U31 ═ K31 ═ I31. K21 and K31 are circuit amplification factors of the amplification circuits inside the first photodetector and the second photodetector. I21 and I31 are the photocurrent of scattered light and the photocurrent of transmitted light, respectively. Wherein, I21 is the photocurrent generated by the laser light with different scattering directions and 360 ° around the axis through the weighted superposition of the reflectors, and the formula is as follows:
wherein η is the loudness of the first photodetector; rθThe parameter R is determined by the design characteristics of the reflectorθThe weighting of the light in different scattering directions is determined.
Further, the cuvette was repeatedly loaded with formalin solutions of different concentrations (e.g., a standard solution concentration of 20NTU or more) to obtain a voltage value corresponding to each standard solution concentration. Obtaining voltage signals U22 and U32 correspondingly from a formalin solution with a concentration of T2, repeating the operation until n groups of mapping data for calibration are obtained, and performing fitting through the n groups of mapping data to obtain a weighted value d1 of a 650nm wavelength optical signal in the scattered optical signal and a weighted value d2 of a 650nm wavelength optical signal in the transmitted optical signal, so as to obtain a first calibration relational expression, thereby constructing a relation between the concentration of a first standard solution and the photovoltage: t ═ U2/(d1 × U2+ d2 × U3). In this embodiment, the influence of the light source fluctuation on the measurement result can be eliminated through the first calibration relation obtained through multiple times of calibration.
When the total organic carbon value of the water quality is measured, a numerical relation between the light intensity and the total organic carbon, namely a second calibration relational expression, can be established in advance in a standard liquid calibration mode. Before the second calibration relation is obtained, a first voltage value U1 corresponding to the reference value of the light intensity of the cuvette cavity needs to be obtained.
Specifically, the light source can be turned on first, the second photoelectric detector continuously collects the light intensity value corresponding to the laser beam with the second wavelength being 275nm, a calculation window is selected, when the standard deviation sigma and the RMS percentage of the light intensity value are smaller than 3%, the operation can be started, then the light intensity value of the cavity at the moment is stored, the first voltage value U1 corresponding to the cavity light intensity reference value is updated, the inversion of the total organic carbon value is carried out on the first voltage value U1 reference value according to the light intensity value in the current test, and a temperature compensation algorithm is matched in the actual process, so that the accuracy of the total organic carbon measurement is improved.
After obtaining the first voltage value U1 corresponding to the reference value of the light intensity of the cavity of the cuvette, the method further includes:
s8, loading a plurality of second standard solutions with different concentrations in the cuvette, respectively carrying out a plurality of groups of experimental calibration to obtain a voltage value corresponding to the concentration of each second standard solution, and carrying out data fitting by the data inversion module according to the concentration of each second standard solution, the voltage value corresponding to the concentration of each second standard solution and the first voltage value U1 to obtain a second calibration relational expression for measuring the total organic carbon value of the water quality of the sample through the second wavelength light beam.
Similarly, potassium metaphosphate solutions with different concentrations are loaded in the cuvette, the laser light source module outputs a combined light beam, the second photoelectric detector receives the transmission light signal and performs photoelectric conversion on the light signal with the second wavelength, namely the wavelength of 275nm, in the transmission light signal to respectively obtain voltage values corresponding to the potassium metaphosphate solutions with different concentrations, so as to obtain multiple groups of calibration data in a mapping relationship, and obtain a second calibration relational expression for measuring the total organic carbon value of the water quality of the sample according to the multiple groups of calibration data.
Optionally, when the laser beam is a combined beam obtained by combining the first wavelength beam and the second wavelength beam, and the cuvette is loaded with the sample water, the S4 includes:
and S4.1, performing photoelectric conversion on the first wavelength light beam in the scattered light signal by the first photoelectric detector to obtain a second voltage value U2 corresponding to the first wavelength light beam.
S4.2, the second photoelectric detector respectively carries out photoelectric conversion on the first wavelength light beam and the second wavelength light beam in the transmitted light signal to obtain a third voltage value U3 corresponding to the first wavelength light beam and a fourth voltage value U4 corresponding to the second wavelength light beam.
Optionally, the S5 includes:
s5.1, the data inversion module performs inversion to obtain the turbidity value of the sample water according to the second voltage value U2, the third voltage value U3 and the first calibration relation;
and S5.2, the data inversion module performs inversion according to the fourth voltage value U4 and the second calibration relational expression to obtain the total organic carbon value of the sample water.
Specifically, when sample water is loaded in the cuvette, the laser light source module emits a combined light beam obtained by combining a 650nm wavelength laser light beam and a 275nm laser light beam, the first photodetector performs photoelectric conversion on a 650nm wavelength optical signal in the scattered light signal to obtain a second voltage value U2 corresponding to the 650nm wavelength optical signal, and the second photodetector performs photoelectric conversion on the 650nm wavelength optical signal in the transmitted light signal to obtain a third voltage value U3 corresponding to the 650nm wavelength optical signal. And the data inversion module substitutes the second voltage value U2 and the third voltage value U3 into the first calibration relational expression to invert to obtain the turbidity value of the sample water.
Optionally, the second photodetector further performs photoelectric conversion on the wavelength optical signal with wavelength of 275nm in the transmitted optical signal to obtain a fourth voltage value U4 corresponding to the wavelength optical signal with wavelength of 275 nm. And substituting the fourth voltage value U4 into the second calibration relational expression by the data inversion module, and performing inversion to obtain the total organic carbon value of the sample water.
In summary, in the novel method and the device for online high-precision measurement of turbidity and total organic carbon provided by the invention, the sample water is detected by the laser beam emitted by the laser light source module, so that the light intensity and the spectral characteristic are stable, the method and the device are not influenced by the test environment, the sensitivity and the anti-interference performance of water quality parameter measurement can be effectively improved, and the laser light source module, the first reflecting prism, the cuvette, the reflecting cover, the second reflecting prism and the quartz lens are sequentially arranged along the light path, so that the laser beam can be turned back for multiple times according to the preset light path, the effective length of the light beam and the water sample to be measured can be increased, the lower limit of the measurement threshold value is further reduced, and the sensitivity of water quality parameter measurement is improved.
Furthermore, in the novel online high-precision method and device for measuring turbidity and total organic carbon provided by the invention, the collected scattered light signals at different angles can be automatically weighted through the reflector, so that the measuring range of water turbidity is expanded, the precision of water quality measurement is improved, the influence of light intensity on a measuring result can be completely eliminated through the two photoelectric detectors and the data inversion module, and the measuring device and the measuring method can also be used for detecting various water quality parameters of water turbidity and total organic carbon at one time, so that the detection efficiency is effectively improved, and the time cost is saved.
The above description is only for the purpose of describing the preferred embodiments of the present invention and is not intended to limit the scope of the present invention, and any variations and modifications made by those skilled in the art based on the above disclosure are within the scope of the present invention.
It should be noted that, although the present invention has been described with reference to the preferred embodiments, the present invention is not limited to the embodiments. It will be apparent to those skilled in the art from this disclosure that many changes and modifications can be made, or equivalents modified, in the embodiments of the invention without departing from the scope of the invention. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention are still within the protection scope of the technical solution of the present invention, unless the content of the technical solution of the present invention is departed from.
In this document, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The above description is only for the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention shall fall within the protection scope of the present invention.
Claims (16)
1. A novel online high-precision turbidity and total organic carbon measuring device is characterized by comprising: the device comprises a laser light source module (10), a water path module (20), a light path returning module (30), a detector module (40) and a data inversion module (50); the waterway module (20) comprises a cuvette (21); the light path turning-back module (30) comprises a first reflecting prism (31), a second reflecting prism (32), a reflecting shade (33) and a quartz lens (34); the detector module (40) comprises a first photodetector (41) and a second photodetector (42); the data inversion module (50) is respectively in communication connection with the first photoelectric detector (41) and the second photoelectric detector (42);
wherein the cuvette (21) contains sample water; the laser water sample device is characterized in that the laser light source module (10), the first reflecting prism (31), the cuvette (21), the reflecting cover (33), the second reflecting prism (32) and the quartz lens (34) are sequentially arranged along a light path, laser beams emitted by the laser light source module (10) are reflected to sample water through the first reflecting prism (31), the laser beams transmitted by the sample water are sequentially transmitted to the second photoelectric detector (42) through reflection of the second reflecting prism (32), re-transmission of the sample water and reflection of the first reflecting prism (31), and the laser beams scattered by the sample water are sequentially transmitted to the first photoelectric detector (41) through reflection of the reflecting cover (33) and convergence of the quartz lens (34).
2. The novel online device for measuring turbidity and total organic carbon with high precision according to claim 1, wherein the laser source module (10) comprises a light source, a beam combining mirror (11) and a shaping lens group (12) sequentially arranged along a light path, the light source outputs laser beams with at least two different wavelengths, the beam combining mirror (11) combines the laser beams with different wavelengths output by the light source and outputs the combined laser beams to the shaping lens group (12), and the shaping lens group (12) collimates the laser beams output by the beam combining mirror (11).
3. The novel device for on-line high-precision measurement of turbidity and total organic carbon according to claim 1, wherein the first reflecting prism (31) is a right-angle prism, and both side surfaces of the first reflecting prism (31) forming a right angle are coated with a broadband reflecting film.
4. The new online device for measuring turbidity and total organic carbon with high precision as claimed in claim 3, wherein said second reflecting prism (32) and said first reflecting prism (31) are all the same in size, shape and material.
5. The new device for on-line high-precision measurement of turbidity and total organic carbon according to claim 1, characterized in that said cuvette (21) is cylindrical in shape and made of quartz material, and the ratio of the height of said cuvette (21) to its own cross-sectional diameter is greater than 4.
6. The new device for on-line high-precision measurement of turbidity and total organic carbon according to claim 5, wherein the height of the reflector (33) is equal to the height of the cuvette (21), and 360 ° is covered on the top surface of the cuvette (21) to surround the cuvette (21), the top end of the reflector (33) is provided with an opening facing the cuvette (21), and the laser beam transmitted by the sample water is directly emitted from the opening to the second reflecting prism (32).
7. The novel device for online high-precision turbidity and total organic carbon measurement according to claim 6, wherein the bottom end of the reflector (33) is fully opened, the diameter of the opening at the bottom end of the reflector (33) is at least equal to 4 times of the height of the cuvette (21), the included angle between the tangential direction of the position where the opening at the top end of the reflector (33) is connected with the side wall of the cuvette (21) and the horizontal direction is 25-40 °, and the included angle between the tangential direction of the edge position at the bottom end of the reflector (33) and the horizontal direction is 50-65 °.
8. The novel device for on-line high-precision measurement of turbidity and total organic carbon according to claim 1, wherein the waterway module (20) further comprises a water supply and drainage unit (22), a water inlet and an overflow port are respectively opened on the upper end and the lower end of the side wall of the cuvette (21), and the water supply and drainage unit (22) is communicated with the water inlet and the overflow port to charge and drain the cuvette (21).
9. The novel online high-precision turbidity and total organic carbon measuring device according to claim 8, wherein the water supply and drainage unit (22) comprises a micro-flow pump (221), a first flow folding device (222), a drainage pump (223), a second flow folding device (224) and a water level detection device (225); the first flow folding device (222) is arranged between the cuvette (21) and the micro-flow pump (221), and a water inlet of the cuvette (21) is respectively connected with the first flow folding device (222) and the drainage pump (223); the overflow port of the cuvette (21) is connected with the water level detection device (225) through the second baffling device (224).
10. The novel device for on-line high-precision turbidity and total organic carbon measurement according to any one of claims 1 to 9, wherein the central axes of the cuvette (21), the first reflecting prism (31), the second reflecting prism (32), the reflector (33) and the quartz lens (34) coincide.
11. A novel online high-precision turbidity and total organic carbon measuring method based on the novel online high-precision turbidity and total organic carbon measuring device as claimed in any one of claims 1 to 10, comprising:
s1, providing a laser beam for high-precision turbidity and total organic carbon measurement by the laser light source module;
s2, providing sample water by the waterway module, and carrying out sample treatment on the sample water;
s3, the light path turning-back module turns back the laser beam according to a preset light path, so that the laser beam passes through the sample water, and a scattered light signal and a transmitted light signal passing through the sample water are obtained;
s4, the detector module performs photoelectric conversion processing on the scattered light signals and the transmitted light signals to obtain electric signals respectively corresponding to the scattered light signals and the transmitted light signals;
and S5, the data inversion module performs inversion according to the electric signals to obtain the turbidity value and the total organic carbon value of the sample water.
12. The novel method for on-line high-precision measurement of turbidity and total organic carbon according to claim 11, wherein the laser beam in S1 comprises one of a first wavelength beam, a second wavelength beam and a third wavelength beam, or a combined beam obtained by combining at least two of the first wavelength beam, the second wavelength beam and the third wavelength beam.
13. The novel on-line high accuracy turbidity and total organic carbon measurement method according to claim 12, wherein when said laser beam is a combined beam of said first wavelength beam and said second wavelength beam, said method further comprises, prior to said water turbidity and total organic carbon measurement of said sample water:
s6, loading a plurality of first standard solutions with different concentrations in the cuvette, respectively carrying out a plurality of groups of experimental calibrations to obtain a voltage value corresponding to the concentration of each first standard solution, and carrying out data fitting by the data inversion module according to the concentration of each first standard solution and the voltage value corresponding to the concentration of each first standard solution to obtain a weighted numerical value d1 of a first wavelength light beam in the scattered light signal and a weighted numerical value d2 of the first wavelength light beam in the transmitted light signal so as to obtain a first calibration relational expression for measuring the water turbidity of the sample water by the first wavelength light beam;
s7, when the cuvette is in a cavity state, the second photodetector performs photoelectric conversion on the second wavelength light beam in the transmitted light signal to obtain a first voltage value U1 corresponding to the second wavelength light beam;
s8, loading a plurality of second standard solutions with different concentrations in the cuvette, respectively carrying out a plurality of groups of experimental calibration to obtain a voltage value corresponding to the concentration of each second standard solution, and carrying out data fitting by the data inversion module according to the concentration of each second standard solution, the voltage value corresponding to the concentration of each second standard solution and the first voltage value U1 to obtain a second calibration relational expression for measuring the total organic carbon value of the water quality of the sample through the second wavelength light beam.
14. The novel on-line high accuracy turbidity to total organic carbon method of claim 13 wherein said first calibration relationship is as follows:
T＝U2/(d1*U2+d2*U3)
wherein T is the turbidity value of the sample water, U2 is a second voltage value obtained by photoelectric conversion of the first wavelength light beam in the scattered light signal, U3 is a third voltage value obtained by photoelectric conversion of the first wavelength light beam in the transmitted light signal, and d2 is the weighted value of the first wavelength light beam in the scattered light signal; d3 is the weighted value of the first wavelength beam in the transmitted light signal.
15. The novel on-line method for measuring turbidity and total organic carbon with high precision according to claim 14, wherein when the laser beam is a combined beam obtained by combining the first wavelength beam and the second wavelength beam, and the cuvette is loaded with the sample water, the step S4 comprises:
s4.1, performing photoelectric conversion on the first wavelength light beam in the scattered light signal by the first photoelectric detector to obtain a second voltage value U2 corresponding to the first wavelength light beam;
s4.2, the second photoelectric detector respectively carries out photoelectric conversion on the first wavelength light beam and the second wavelength light beam in the transmitted light signal to obtain a third voltage value U3 corresponding to the first wavelength light beam and a fourth voltage value U4 corresponding to the second wavelength light beam.
16. The novel on-line high accuracy method for measuring turbidity and total organic carbon according to claim 15, wherein said S5 comprises:
s5.1, the data inversion module performs inversion to obtain the turbidity value of the sample water according to the second voltage value U2, the third voltage value U3 and the first calibration relation;
and S5.2, the data inversion module performs inversion according to the fourth voltage value U4 and the second calibration relational expression to obtain the total organic carbon value of the sample water.
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| CN114354501B (en) * | 2021-11-22 | 2023-12-08 | 中国科学院西安光学精密机械研究所 | Self-cleaning type high-precision in-situ water turbidity online detection device and method |
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