Online COD (Chemical Oxygen Demand) analyzer adopting UV (Ultraviolet) method

Abstract

The utility model discloses an online COD (Chemical Oxygen Demand) analyzer adopting a UV (Ultraviolet) method. The online COD analyzer comprises a first colorimetric unit, a second colorimetric unit, a liquid inlet unit, a peristaltic pump and a liquid discharge control valve, the first colorimetric unit comprises a first colorimetric pool as well as a visible light source, a visible light detector and a reference detector which are arranged on the outer side of the first colorimetric pool; light emitted by the visible light source is divided into two beams, one beam of light penetrates through the first colorimetric pool and is received by the visible light detector, and the other beam of light avoids the first colorimetric pool and is received by the reference detector; the second colorimetric unit comprises a second colorimetric pool as well as an ultraviolet light source and an ultraviolet light detector which are arranged on the outer side of the second colorimetric pool; light emitted by the ultraviolet light source penetrates through the second colorimetric pool and is received by the ultraviolet light detector; an outlet of the liquid inlet unit is connected with inlets of the first colorimetric pool and the second colorimetric pool through a peristaltic pump and a pipeline, and outlets of the first colorimetric pool and the second colorimetric pool are connected with a liquid discharge control valve through a pipeline. According to the utility model, the interference of water sample color can be eliminated, and the COD can be accurately measured.

Description

Technical Field

[0001] The utility model relates to the technical field of COD detection, and particularly relates to an online COD analyzer using the UV method. Background Art

[0002] Chemical oxygen demand (COD) refers to the amount of oxidant consumed when treating a water sample with a strong oxidant under certain conditions, usually expressed in mg / L. The COD value can reflect the degree of organic pollution of the water body. The larger the value, the more organic matter is contained in the water body, and the more likely it is to cause eutrophication of the water body and damage to the ecosystem. Therefore, the determination of COD is particularly important for the protection and management of water resources and is a key indicator for evaluating the degree of organic pollution of the water body.

[0003] Currently, the commonly used methods for COD determination include the dichromate method, the permanganate method, the rapid digestion method, the spectrophotometry method, etc. Compared with the chemical method, when measuring COD using the relationship between absorbance and COD concentration, no chemical reagents need to be added, and no heating and digestion are required, so the measurement is relatively convenient. However, it is easily interfered by the color of the water body and needs to be improved. Summary of the Utility Model

[0004] The purpose of the utility model is to provide an online COD analyzer using the UV method, which can eliminate the interference of the color of the water sample and accurately measure COD.

[0005] In order to achieve the above purpose, the technical scheme adopted by the utility model is as follows:

[0006] An online COD analyzer using the UV method includes a first colorimetric unit, a second colorimetric unit, a liquid inlet unit, a peristaltic pump and a drain control valve; the first colorimetric unit includes a first colorimetric cell and a visible light source, a visible light detector and a reference detector arranged outside the first colorimetric cell; the light emitted by the visible light source is divided into two beams, one of which passes through the first colorimetric cell and is received by the visible light detector, and the other beam bypasses the first colorimetric cell and is received by the reference detector; the second colorimetric unit includes a second colorimetric cell and an ultraviolet light source and an ultraviolet light detector arranged outside the second colorimetric cell; the light emitted by the ultraviolet light source passes through the second colorimetric cell and is received by the ultraviolet light detector.

[0007] The outlet of the liquid inlet unit is connected to the inlets of the first colorimetric cell and the second colorimetric cell through the peristaltic pump and a pipeline, and the outlets of the first colorimetric cell and the second colorimetric cell are connected to the drain control valve through a pipeline.

[0008] Further, the first colorimetric unit further includes a fixing seat, the fixing seat is disposed around the outside of the first colorimetric cell, the visible light source, the visible light detector, and the reference detector are all disposed on the fixing seat, and the portion of the first colorimetric cell exposed outside the fixing seat is shielded from light.

[0009] Further, a piece of tin foil is attached to the outer side surface of the first colorimetric cell, and the tin foil is used for shielding light.

[0010] Further, the visible light source and the visible light detector are oppositely disposed on both sides of the first colorimetric cell, and the reference detector is located below the visible light source.

[0011] Further, the visible light detector, the reference detector, and the ultraviolet light detector are all silicon photocell detectors.

[0012] Further, the wavelength of the visible light source is 500 - 600 nm, and the wavelength of the ultraviolet light source is 200 - 300 nm.

[0013] Further, the wavelength of the visible light source is 525 nm, and the wavelength of the ultraviolet light source is 255 nm.

[0014] Further, the liquid inlet unit includes a first injection valve, a second injection valve, a third injection valve, a first connector, a second connector, a third connector, a pure water pipe, a cleaning pipe, a standard solution pipe, and a sample pipe; the first injection valve, the second injection valve, and the third injection valve are all two-way solenoid valves, and the first connector, the second connector, and the third connector are all three-way connectors.

[0015] The pure water pipe is sequentially connected to the normal open end of the first injection valve, the first connector, the normal open end of the second injection valve, the second connector, the normal open end of the third injection valve, and the third connector; the cleaning pipe is sequentially connected to the control end of the first injection valve and the first connector; the standard solution pipe is sequentially connected to the control end of the second injection valve and the second connector; the sample pipe is sequentially connected to the control end of the third injection valve and the third connector; the third connector is connected to the inlet of the peristaltic pump.

[0016] Further, it further includes a water sample detector, and the water sample detector is installed on the pipeline between the liquid inlet unit and the peristaltic pump.

[0017] Further, it further includes a fourth connector, the fourth connector is a three-way connector, the drain control valve is a two-way solenoid valve, one end of the fourth connector is externally connected to a waste liquid pipe, and the other two ends are respectively connected to the normal open end and the control end of the two-way solenoid valve through pipelines; the inlet of the first colorimetric cell is connected to the peristaltic pump, and the top outlet is connected to the normal open end of the drain control valve.

[0018] The utility model has the following beneficial effects:

[0019] The utility model provides a UV method online COD analyzer, which has two colorimetric units. When in use, the color of the water sample can be measured by the visible light source and the visible light detector in the first colorimetric unit. At the same time, the COD content in the water sample can be measured by the ultraviolet light source and the ultraviolet light detector in the second colorimetric unit. Combining the results measured by the first colorimetric unit can exclude the interference of the water sample color and calculate a more accurate COD value. In addition, a reference detector is provided in the first colorimetric unit to correct the parameters, which can make the COD measurement result more accurate. Description of the Drawings

[0020] Figure 1 It is a schematic structural diagram of the utility model.

[0021] Description of the main component symbols: 1. The first colorimetric unit; 11. The first colorimetric cell; 12. The visible light source; 13. The visible light detector; 14. The reference detector; 15. The fixed seat; 2. The second colorimetric unit; 21. The second colorimetric cell; 22. The ultraviolet light source; 23. The ultraviolet light detector; 3. The liquid inlet unit; 31. The first sampling valve; 32. The second sampling valve; 33. The third sampling valve; 34. The first joint; 35. The second joint; 36. The third joint; 4. The peristaltic pump; 5. The drain control valve; 6. The water sample detector; 7. The fourth joint; H. The pure water pipe; WS. The cleaning pipe; C. The standard solution pipe; S. The sample pipe; W. The waste liquid pipe. Detailed Embodiments

[0022] The following further describes the utility model in conjunction with the drawings and specific embodiments.

[0023] As Figure 1 shown, the utility model discloses a UV method online COD analyzer, which includes a first colorimetric unit 1, a second colorimetric unit 2, a liquid inlet unit 3, a peristaltic pump 4 and a drain control valve 5.

[0024] The first colorimetric unit 1 includes a first colorimetric cell 11, and a visible light source 12, a visible light detector 13, a reference detector 14 and a fixing base 15 arranged outside the first colorimetric cell 11. The first colorimetric cell 11 is a vertically tubular glass colorimetric tube. The visible light source 12 and the visible light detector 13 are oppositely arranged on both sides of the first colorimetric cell 11 and are on the same horizontal plane, while the reference detector 14 is arranged below the visible light source 12. The light emitted by the visible light source 12 is split into two beams by a beam splitter. One beam of light can pass through the first colorimetric cell 11 and is received by the visible light detector 13, and the other beam of light bypasses the first colorimetric cell 11 and is received by the reference detector 14. Through the visible light source 12 and the visible light detector 13 in the first colorimetric unit 1, the color of the water sample in the first colorimetric cell 11 can be measured, so as to exclude various interferences caused by the color of the water sample in the subsequent COD value calculation and improve the accuracy of the analyzer for measuring COD.

[0025] The fixing base 15 is integrally annular and is arranged around the middle part outside the first colorimetric cell 11. The inner side surface of the fixing base 15 fits the outer side surface of the first colorimetric cell 11 to wrap the middle part of the first colorimetric cell 11. The visible light source 12, the visible light detector 13 and the reference detector 14 are correspondingly arranged on the fixing base 15. The part of the first colorimetric cell 11 exposed outside the fixing base 15 is shielded from light. In this embodiment, a tin foil is used for light shielding treatment. The tin foil is attached to the outer side surface of the first colorimetric cell 11 to shield the part of the first colorimetric cell 11 exposed outside the fixing base 15, so as to avoid the influence of external light on the measurement result.

[0026] The second colorimetric unit 2 includes a second colorimetric cell 21, and an ultraviolet light source 22 and an ultraviolet light detector 23 arranged outside the second colorimetric cell 21. The ultraviolet light source 22 and the ultraviolet light detector 23 are oppositely arranged, and the light emitted by the ultraviolet light source 22 can pass through the second colorimetric cell 21 and is received by the ultraviolet light detector 23. The COD content in the water sample is measured by the ultraviolet light source 22 and the ultraviolet light detector 23 in the second colorimetric unit 2.

[0027] The above-mentioned visible light detector 13, reference detector 14 and ultraviolet light detector 23 all adopt silicon photocell detectors, which have the characteristics of stable performance and wide spectral range. The wavelength of the visible light source 12 is 500 - 600 nm, and the wavelength of the ultraviolet light source 22 is 200 - 300 nm. Preferably, the wavelength of the visible light source 12 is selected as 525 nm, and the wavelength of the ultraviolet light source 22 is 255 nm.

[0028] The outlet of the liquid inlet unit 3 is connected to the inlets of the first colorimetric cell 11 and the second colorimetric cell 21 through a peristaltic pump 4. When connecting, the first colorimetric cell 11 and the second colorimetric cell 21 can be arranged in series to measure the water sample successively, or can be connected in parallel to measure the water sample simultaneously. A water sample detector 6 is also provided at the outlet of the liquid inlet unit 3. The water sample detector 6 is installed on the pipeline between the liquid inlet unit 3 and the peristaltic pump 4, and can ensure that liquids such as water samples, cleaning liquids, and pure water enter the flow path during measurement or cleaning. The outlets of the first colorimetric cell 11 and the second colorimetric cell 21 are connected to a drain control valve 5 through a pipeline.

[0029] In this embodiment, the liquid inlet unit 3 includes a first injection valve 31, a second injection valve 32, a third injection valve 33, a first joint 34, a second joint 35, a third joint 36, a pure water pipe H, a cleaning pipe WS, a standard solution pipe C, and a sample pipe S. The first injection valve 31, the second injection valve 32, and the third injection valve 33 are all two-way solenoid valves, and the first joint 34, the second joint 35, and the third joint 36 are all three-way tower joints.

[0030] The first injection valve 31, the first joint 34, the second injection valve 32, the second joint 35, the third injection valve 33, and the third joint 36 are arranged in sequence. The pure water pipe H is sequentially connected to the normal open end of the first injection valve 31, the first joint 34, the normal open end of the second injection valve 32, the second joint 35, the normal open end of the third injection valve 33, and the third joint 36. The cleaning pipe WS is sequentially connected to the control end of the first injection valve 31 and the first joint 34. The standard solution pipe C is sequentially connected to the control end of the second injection valve 32 and the second joint 35. The sample pipe S is sequentially connected to the control end of the third injection valve 33 and the third joint 36. The remaining end on the third joint 36 is connected to the inlet of the peristaltic pump 4, and the above-mentioned water sample detector 6 is provided on the mutually connected pipeline. By opening and closing the first injection valve 31, the second injection valve 32, and the third injection valve 33, pure water, cleaning liquid, standard solution, and water sample can be introduced into the flow path accordingly.

[0031] Similarly, the above-mentioned drain control valve 5 also adopts a two-way solenoid valve. The analyzer is also provided with a fourth joint 7 and a waste liquid pipe W. The fourth joint 7 also adopts a three-way tower joint. One end of the fourth joint 7 is externally connected to the waste liquid pipe W, and the other two ends are respectively connected to the normal open end and the control end of the two-way solenoid valve through pipelines. Correspondingly, the first colorimetric unit 1 and the second colorimetric unit 2 are arranged successively. The inlet on the side of the first colorimetric cell 11 is connected to the other end on the peristaltic pump 4, and then connected to the liquid inlet unit 3. The outlet on the top is connected to the control end of the drain control valve 5, and the outlet on the bottom is connected to the inlet of the second colorimetric cell 21. The outlet of the second colorimetric cell 21 is connected to the normal open end of the drain control valve 5. By opening and closing the drain control valve 5, the outlets of the first colorimetric cell 11 and the second colorimetric cell 21 can be opened and closed accordingly for draining.

[0032] Since the constituents of COD in wastewater have strong absorption peaks in the ultraviolet spectral region, while the absorption wavelengths of the water body color are all in the visible light region, when using this analyzer, the color of the water sample is measured by the first colorimetric unit 1, and the absorbance corresponding to the characteristic wavelength of the organic matter is measured by the second colorimetric unit 2. Combining the measured values obtained by detecting with the visible light detector 13 and the ultraviolet light detector 23 and the reference values obtained by detecting with the reference detector 14 can exclude various interferences caused by the color of the water sample, and a relatively accurate COD value can be calculated. The whole measurement process can be carried out continuously online, without adding reagents and without heating and digestion. It is not only convenient to operate, but also can avoid the human errors caused by reagent addition and digestion operations. It can be seen that this analyzer has good reproducibility and accuracy, and the analysis and measurement are fast.

[0033] Although the present invention has been specifically shown and described in conjunction with the preferred embodiments, those skilled in the art should understand that various changes can be made to the present invention in form and detail without departing from the spirit and scope of the present invention defined by the appended claims, and all such changes are within the protection scope of the present invention.

Claims

1. A UV method online COD analyzer, characterized in that: It includes a first colorimetric unit, a second colorimetric unit, a liquid inlet unit, a peristaltic pump and a liquid discharge control valve; The first colorimetric unit comprises a first colorimetric cell and a visible light source, a visible light detector and a reference detector arranged outside the first colorimetric cell; the light emitted by the visible light source is divided into two beams, one of which passes through the first colorimetric cell and is received by the visible light detector, and the other avoids the first colorimetric cell and is received by the reference detector; The second colorimetric unit includes a second colorimetric cell and an ultraviolet light source and an ultraviolet light detector arranged outside the second colorimetric cell; light emitted by the ultraviolet light source passes through the second colorimetric cell and is received by the ultraviolet light detector; The outlet of the liquid inlet unit is connected to the inlets of the first colorimetric cell and the second colorimetric cell through the peristaltic pump and the pipeline, and the outlets of the first colorimetric cell and the second colorimetric cell are connected to the discharge control valve through the pipeline.

2. A UV method online COD analyzer as claimed in claim 1, characterized in that: The first colorimetric unit also includes a fixing base, which is arranged around the outside of the first colorimetric cell. The visible light source, the visible light detector and the reference detector are all arranged on the fixing base, and the first colorimetric cell is partially exposed from the fixing base and is light-shielded.

3. A UV method online COD analyzer as claimed in claim 2, characterized in that: A tin foil is attached to the outer surface of the first colorimetric cell, and the tin foil is used for shading.

4. A UV method online COD analyzer as claimed in claim 2, characterized in that: The visible light source and the visible light detector are arranged opposite to each other at two sides of the first colorimetric cell, and the reference detector is located below the visible light source.

5. A UV method online COD analyzer as claimed in claim 1, characterized in that: The visible light detector, the reference detector and the ultraviolet light detector are all silicon photocell detectors.

6. A UV method online COD analyzer as claimed in claim 1, characterized in that: The wavelength of the visible light source is 500-600 nm, and the wavelength of the ultraviolet light source is 200-300 nm.

7. A UV method online COD analyzer as claimed in claim 6, characterized in that: The wavelength of the visible light source is 525 nm, and the wavelength of the ultraviolet light source is 255 nm.

8. A UV method online COD analyzer as claimed in claim 1, characterized in that: The liquid inlet unit includes a first injection valve, a second injection valve, a third injection valve, a first joint, a second joint, a third joint, a pure water pipe, a cleaning pipe, a standard liquid pipe and a sample pipe; the first injection valve, the second injection valve and the third injection valve are all two-way solenoid valves, and the first joint, the second joint and the third joint are all three-way joints; The pure water pipe is connected in sequence to the normally open end of the first injection valve, the first joint, the normally open end of the second injection valve, the second joint, the normally open end of the third injection valve and the third joint; the cleaning pipe is connected in sequence to the control end of the first injection valve and the first joint; the standard liquid pipe is connected in sequence to the control end of the second injection valve and the second joint; the sample tube is connected in sequence to the control end of the third injection valve and the third joint; the third joint is connected to the inlet of the peristaltic pump.

9. A UV method online COD analyzer as claimed in claim 1, characterized in that: It also includes a water sample detector, which is installed on the pipeline between the liquid inlet unit and the peristaltic pump.

10. A UV method online COD analyzer as claimed in claim 1, characterized in that: It also includes a fourth joint, which is a three-way joint, and the discharge control valve is a two-way solenoid valve. One end of the fourth joint is connected to a waste liquid pipe, and the other two ends are connected to the normally open end and the control end of the two-way solenoid valve through pipelines; the inlet of the first colorimetric cell is connected to the peristaltic pump, the top outlet is connected to the control end of the discharge control valve, the bottom outlet is connected to the inlet on the second colorimetric cell, and the outlet on the second colorimetric cell is connected to the normally open end of the discharge control valve.

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