CN102798602B - Integrated dual-beam water quality COD on-line detection sensor - Google Patents

Abstract

The present invention provides an integrated dual-beam water quality COD on-line detection sensor. The sensor body is provided with a UVLED array, a measurement light chamber, a reference light chamber and a detection light path; the UVLED array is composed of an even number of symmetrically arranged LED lights, driven by The device is driven; the UVLED array and the center of the detection light path are on a straight line; the measuring light chamber is a rectangular groove opened in the middle of the sensor body, and the two sides of the groove along the axial direction of the sensor body are provided with the same straight line The collimating mirror and the outgoing condenser mirror; the reference light chamber and the second UVLED array on the sensor body and the center of the second detection optical path are in a straight line. The invention adopts LED array as the light source of the sensor, which greatly simplifies the structure of the sensor; greatly reduces the volume and weight of the sensor, and adopts the measurement light chamber and the reference light chamber group to improve the accuracy of water quality detection; the sensor is an immersion integrated The sensor enables it to detect the water quality on-line, making the measurement more convenient.

Description

Integrated dual-beam water quality COD online detection sensor

technical field

The invention relates to the technical field of detection sensors, in particular to an integrated dual-beam water quality COD on-line detection sensor for water quality monitoring.

Background technique

COD (Chemical Oxygen Demand, chemical oxygen demand) is an important indicator of water quality testing, which is used to reflect the degree of pollution of reducing substances in water. Since the reducing substances in water are mainly organic substances, COD also reflects the degree of pollution of water by organic substances. degree of pollution. The smaller the COD value, the lighter the water quality is polluted by organic matter.

At present, COD determination methods are mainly divided into chemical and physical methods, and the traditional chemical method is mainly chemical titration (potassium dichromate or potassium permanganate). This method is mainly based on manual on-site sampling and laboratory instrument analysis, which has low monitoring frequency, large sampling error, scattered monitoring data, long time period required, many intermediate links, and easy to cause secondary pollution. It cannot reflect the pollution changes in real time, and it is difficult to meet the demand for effective water environment management.

The physical method is to use ultraviolet (UV) analysis method, which uses the absorption characteristics of most organic substances at a certain wavelength (such as 254nm), and irradiates the water body with ultraviolet light of this specific wavelength to judge water pollution from the absorbance. Degree. In order to reduce the impact of turbidity, chromaticity, etc. on the measurement, dual-wavelength measurement is generally used, and the other wavelength (546nm) is used as a reference light to eliminate the impact of water turbidity, chromaticity, etc. on the measurement. Advantages No need to add chemical reagents, no secondary pollution, and easy to realize online automation, easy long-term stable operation and maintenance of the instrument.

With the continuous deepening of the research on ultraviolet absorption spectroscopy in the field of water quality detection, there are many detection methods using dual wavelengths or multiple bands. For example CN200810064473.2 discloses "an on-line detector for measuring COD concentration by ultraviolet absorption method". Water body COD has a good correlation to calculate the COD value. The 546nm visible light absorbance is used to calculate the turbidity of the water sample, and then the error caused by the turbidity is subtracted from the COD value to improve the measurement accuracy.

The literature (Design of a new online water quality (COD) automatic monitor based on the principle of ultraviolet (UV) absorption, Du Zhengong et al., Science and Technology Wind, 2011 (18), 48-51) discloses that the detector consists of a water system, an optical system and a data processing system. Composition, the test instrument is placed outside the water body, the peristaltic pump is used to continuously and stably draw water samples, the xenon lamp is used as the light source, and the COD content of the water body is also monitored by dual wavelengths. For the problem of long-term stable operation of the light source, the intensity measurement of the reference beam is introduced for feedback comparison to eliminate nonlinear errors.

CN200710119027.2 discloses its corresponding detection device for the former, and this device is made up of ultraviolet light source, sample cell, spectrometer, ultraviolet light intensity detector and data processor, adopts multi-wavelength ultraviolet measurement, according to the ultraviolet light output of ultraviolet light intensity detector The light intensity of each wavelength of the beam is used to calculate the absorbance of organic matter, so that accurate chemical oxygen demand (COD) can be obtained in a large application range.

The above existing technologies all use mercury lamp or xenon lamp as the light source, but the structural design of this type of light source is troublesome, the cost and maintenance cost are relatively high, the power consumption is quite large, and the luminous life is not very long. Both the previous two articles use dual wavelengths to measure COD, which can only measure the content of most organic substances, and the reference light cannot eliminate the interference of a small amount of inorganic substances, trace elements and metal ions in the water quality on the ultraviolet absorption spectrum of organic substances, resulting in insufficient measured values. precise. Although the latter selects multiple bands with relatively large absorbance to measure the COD value, which can improve the accuracy to a certain extent, but the correlation coefficient needs to be determined by chemical methods when calculating COD. Therefore, when the sewage composition and external conditions change, the band range The number of bands needs to be reselected, and the correlation coefficient also needs to be remeasured, so the measurement process is relatively complicated, and the so-called real-time performance cannot be guaranteed.

Contents of the invention

Aiming at the above-mentioned defects existing in the prior art, the present invention solves the problems that the existing water quality COD detection sensor adopts mercury lamp or xenon lamp as the light source, which has complex structure, high cost, power consumption and luminous life, and provides a novel structure Integrated dual-beam water quality COD online detection sensor.

Solve above-mentioned technical problem, the technical scheme that the present invention adopts is as follows:

The integrated double-beam water quality COD online detection sensor is characterized in that it includes a sensor body, a measurement light chamber and a detection light path; the measurement light chamber is a rectangular groove opened in the middle of the sensor body, and the measurement light chamber is along the axis of the sensor body The two side walls of the direction are provided with a collimating mirror and an outgoing condenser mirror on the same straight line; the detection optical path is composed of a sensor light source, an incident condenser mirror, an incident optical fiber, a collimating mirror, an outgoing condenser mirror and an outgoing optical fiber on the same straight line; The light source of the sensor is a UVLED array, and the light emitted by the sensor light source is transmitted through the incident condenser lens and the incident optical fiber, coupled by the collimator lens, then absorbed by the solution to be measured through the measuring light chamber, and coupled into the outgoing optical fiber through the outgoing condenser lens for transmission. ;

In the middle of the sensor body, there is also a reference light chamber with the same length and the same axial position as the measurement light chamber, and a sealing insert is also provided on the reference light chamber; The second collimating mirror and the second exit condenser lens on the top; the second detection light path is also provided corresponding to the reference light chamber, and the second detection light path is on the same straight line of the second sensor light source UVLED array, the second incident condenser lens , a second incident optical fiber, a second collimator, a second outgoing condenser and a second outgoing optical fiber; the light emitted by the second sensor light source UVLED array (26) passes through the second incident condenser (25), the second incident optical fiber (24 ) is coupled by the second collimating mirror (23), and then absorbed by the standard solution through the reference light chamber (11), and then coupled to the second outgoing optical fiber through the second outgoing condenser lens for transmission;

Finally, the double-beam detection is realized through the comparison between the measurement light chamber and the reference light chamber, and the accuracy of the measurement results is improved.

The function of the UVLED array is to provide the required ultraviolet spectrum as a light source; the function of the collimator is to converge and transmit the UVLED array into a parallel light speed, which ensures better transmission of the light beam in the measuring light chamber or the reference light chamber.

The function of the sensor body is to achieve double-beam detection through the comparison between the measurement light chamber and the reference light chamber, and improve the accuracy of the measurement results. .

The functions of the incident optical fiber and the outgoing optical fiber are to improve the continuous light guiding efficiency of the light beam in the ultraviolet region wavelength in the optical fiber, and overcome the shortcoming of low light guiding efficiency of the general optical fiber to the ultraviolet light beam.

The function of the sealing insert is to facilitate the replacement of the reference solution in the reference light chamber, so as to ensure the quality of the reference measurement solution.

Compared with the prior art, the present invention has the following beneficial effects:

1. The integrated double-beam water quality COD online detection sensor described in the present invention adopts an LED array as the light source of the sensor, which greatly simplifies the structure of the sensor; and greatly reduces the volume and weight of the sensor. Tungsten lamps and xenon lamps are used as light source probes, with low cost, low power consumption, long service life, better stability, and no need for follow-up maintenance. The structure of the sensor is simple, and the use of the sensor has high performance-price ratio and is convenient to use.

2. The LED array light source of the present invention adopts a plurality of LEDs to form a continuous wave band to realize the continuous wavelength detection of water quality COD, so that the measurement results can accurately reflect the value of water body COD in a large range, greatly reducing a small amount of inorganic substances, trace elements and The absorbance of metal ions in the ultraviolet band interferes with the absorbance of organic substances and improves the measurement accuracy.

3. The present invention adopts a measurement light chamber and a reference light chamber in the sensor body, realizes comparative detection through double beams, and further improves measurement accuracy, and the sensor is placed in a water body to realize immersion real-time monitoring. Make measurement more convenient.

Description of drawings

Fig. 1 schematic diagram of the online detection sensor of the present invention

Fig. 2 is a sectional structure diagram of the sensor body according to the present invention

Fig. 3 is a schematic diagram of the UVLED array light source according to the present invention.

In the figure: 1-exit fiber, 2-exit condenser, 3-collimator, 4-incident light, 5-incidence condenser, 6-UVLED array, 7-light source drive, 8-drive cable, 9-sensor body, 10-Measuring light chamber, 11-Reference light chamber, 12-Sealing plug-in, 13-Exit fiber through hole, 14-Drive cable through hole. 21-the second outgoing optical fiber, 22-the second outgoing condenser, 23-the second collimator, 24-the second incident light, 25-the second incident condenser, 26-the second UVLED array.

Detailed ways

Referring to Fig. 1, Fig. 2 and Fig. 3, the integrated double-beam water quality COD online detection sensor is characterized in that it includes a sensor body 9, a measurement light chamber 10 and a detection light path; the measurement light chamber 10 is set in the middle of the sensor body 9 The measuring light chamber 10 is provided with a collimating mirror 3 and an outgoing condenser lens 2 on the same straight line on both side walls along the axial direction of the sensor body 9; , incident condenser 5, incident optical fiber 4, collimating mirror 3, outgoing condenser 2 and outgoing optical fiber 1; The straight mirror 3 is coupled, and then absorbed by the solution to be measured through the measuring light chamber 10, coupled to the outgoing optical fiber 1 through the outgoing condenser lens 2, and transmitted;

A reference light chamber 11 with the same length and axial position as the measurement light chamber 10 is also provided in the middle part of the sensor body 9, and a sealing insert 12 is also provided on the reference light chamber 11; The second collimating mirror 23 and the second exit condenser lens 22 on the same straight line are arranged on the same straight line; the second detection optical path is also provided corresponding to the reference light chamber 11, and the second detection optical path is on the same straight line. The sensor light source UVLED array 26, the second incident condenser lens 25, the second incident optical fiber 24, the second collimator mirror 23, the second outgoing condenser lens 22 and the second outgoing optical fiber 21 constitute; the light emitted by the second sensor light source UVLED array 26 passes through the second After the transmission of the second incident condenser lens 25 and the second incident optical fiber 24, it is coupled through the second collimating mirror 23, and after being absorbed by the standard solution through the reference light chamber 11, it is coupled into the second outgoing optical fiber 21 through the second outgoing condenser lens 22 to carry out transmission;

Finally, through the comparison between the measurement light chamber 10 and the reference light chamber 11, the double-beam detection is realized, and the accuracy of the measurement result is improved.

The optional range of the optical path difference between the measuring light chamber 10 and the reference light chamber 11 is: 0.5-30mm.

The function of the UVLED array is to provide the required ultraviolet spectrum as a light source; the function of the collimator is to converge and transmit the UVLED array into a parallel light speed, which ensures better transmission of the light beam in the measurement light chamber or reference light chamber.

The function of the sensor body is to achieve double-beam detection through the comparison between the measurement light chamber and the reference light chamber, and improve the accuracy of the measurement results. . The function of the incident optical fiber and the outgoing optical fiber is to improve the continuous light guide efficiency of the beam in the ultraviolet region wavelength in the optical fiber, and overcome the disadvantage of low light guide efficiency of the general optical fiber to the ultraviolet beam. The function of the sealing insert 12 is to facilitate the replacement of the reference solution in the reference light chamber to ensure the quality of the reference measurement solution.

Among them, the light source drive converts the voltage of 220v into the stable voltage drop required by the UVLED array, drives the UVLED array to emit light, and the UVLED array couples the light source to the incident optical fiber through the condenser lens, and the incident optical fiber transmits the light beam to the measurement optical chamber or reference optical chamber. The straight mirror is coupled into it, and after the light is absorbed by the solution in the cell through the measuring light chamber or the reference light chamber, it is coupled into the outgoing optical fiber by the condenser lens for transmission.

According to a preferred solution of the present invention, the UVLED array selects LED lamps of the required spectrum and arranges them in parallel to form an LED array to provide a light source of the required ultraviolet spectrum. The LED light source has the advantages of small size, low power consumption, long life, and stable operation. Using the LED array as the light source greatly simplifies the structure of the sensor, and greatly reduces the volume and weight of the light source.

The sensor body adopts the comparison between the measurement light chamber and the reference light chamber to realize double-beam detection. The sensor is immersed in the measurement solution to realize the immersion and online detection of water quality. The reference light chamber is equipped with a standard solution. The comparison of the measurement light chamber and the reference light chamber to improve the accuracy of the measurement results.

According to a preferred solution of the present invention, the function of the incident optical fiber 4 and the outgoing optical fiber 1 is to improve the continuous light guiding efficiency of the light beam in the ultraviolet region wavelength in the optical fiber, which overcomes the disadvantage of low light guiding efficiency of the general optical fiber to the ultraviolet light beam.

The present invention is based on the principle that most organic substances are reflected in the absorption spectrum of the ultraviolet band, but different organic substances have different absorbances at the same wavelength in the ultraviolet band, and the absorbance of the same organic matter at different wavelengths in the ultraviolet band is different. The LED array light source forms a continuous wavelength to realize the continuous wavelength detection of water quality COD. Double beams are used for comparison to improve measurement accuracy.

Claims (1)

1. integrated twin-beam water-quality COD detecting line sensor, is characterized in that, comprises sensor body (9), measures light room (10) and detect light path; Described measurement light room (10) is at the rectangular recess offered of sensor body (9) middle part, and described measurement light room (10) is provided with collimating mirror (3) on the same line and outgoing condenser (2) along the two side that sensor body (9) is axial; Described detection optical routing is in the sensor light source on same straight line, incident condenser (5), incident optical (4), collimating mirror (3), outgoing condenser (2) and outgoing optical fiber (1) and forms; Described sensor light source is UVLED array (6), the light that sensor light source sends is coupled through collimating mirror (3) after the transmission of incident condenser (5), incident optical (4), absorbed by solution to be measured by measuring light room (10) again, be coupled in outgoing optical fiber (1) through outgoing condenser (2), transmit;

Also be provided with axial location identical reference light room (11) identical with described measurement light room (10) length at sensor body (9) middle part, described reference light room (11) is also provided with sealed inserted piece (12); Reference light room (11) two side is provided with the second collimating mirror (23) on the same line and the second outgoing condenser (22); Corresponding described reference light room (11) is also provided with the second detection light path, and the second sensor light source UVLED array (26), the second incident condenser (25), the second incident optical (24), the second collimating mirror (23), the second outgoing condenser (22) and the second outgoing optical fiber (21) that described second detection optical routing is on same straight line are formed; The light that second sensor light source UVLED array (26) sends is coupled through the second collimating mirror (23) after the transmission of the second incident condenser (25), the second incident optical (24), after being absorbed by standard solution by reference to light room (11) again, be coupled in the second outgoing optical fiber (21) through the second outgoing condenser (22), transmit;

Realize twin-beam detection finally by the comparison of measuring between light room (10) and reference light room (11), improve the precision of measurement result;

Described sensor light source UVLED array (6,26) is made up of the ultraviolet LED lamp of 4 ~ 6 symmetric offset spread, is driven by drive unit (7);

The optical path difference range of choices of described measurement light room (10) and reference light room (11) is: 0.5-30mm;

Described sensor body (9) is list structure, and its section is circular or rectangle.