Light path structure for total nitrogen online monitor

Abstract

The utility model relates to the technical field of water quality on-line automatic measurement, and provides a light path structure for a total nitrogen on-line monitor, which comprises a light source, a light source correction module, a digestion module and a detection module, the light source and the light source correction module are arranged on one side of the digestion module, and the detection module is arranged on the other side of the digestion module; the light source correction module comprises a collimator; the digestion module comprises a digestion chamber, and a digestion pipe is arranged in the digestion chamber; the utility model has the advantages of simple structure, small volume, low cost, no mechanical moving part, no follow-up maintenance problem, convenience in installation and use and the like; according to the present invention, the requirements of the national standard method on the total nitrogen test and the collection and analysis on the 220nm wavelength and the 275nm wavelength by using the dual ultraviolet spectrophotometry are met, the problems of complex light path device and high practical imported optical filter cost of the existing total nitrogen online monitor are solved, and the influence of the actual water sample turbidity can be deducted by adding the 880nm detection wavelength.

Description

Technical Field

[0001] The utility model relates to the technical field of online automatic measurement of water quality, in particular to an optical path structure used for an online total nitrogen monitor. Background Art

[0002] In water environment monitoring, total nitrogen is a very important indicator. At present, the total nitrogen water quality online monitor usually draws on the national standard laboratory analysis method, which requires the use of dual ultraviolet spectrophotometry (220nm, 275nm) to analyze the nitrate after digestion. At 120-124°C, the alkaline potassium persulfate solution converts the nitrogen of the nitrogen-containing compounds in the sample into nitrate, and the ultraviolet spectrophotometry is used to measure the absorbance A at wavelengths of 220nm and 275nm, respectively. 220 and A 275 , according to the formula: A=A 220 -2A 275 The corrected absorbance A is calculated. The total nitrogen (N) content is proportional to the corrected absorbance A.

[0003] The application of photometric total nitrogen to surface water is easily interfered by the turbidity of surface water. The combustion method of total nitrogen on the market can solve the problem of turbidity interference, but the cost is high, which is 3-4 times that of photometric method. Therefore, people in this field need to design an optical path structure of an online total nitrogen water quality monitor based on the principle of photometric method, which can achieve good data stability and meet the application scenarios of surface water. Utility Model Content

[0004] In order to achieve the above purpose, the utility model provides the following technical solutions:

[0005] The utility model provides an optical path structure for a total nitrogen online monitor, comprising a light source, a light source correction module, a digestion module and a detection module, wherein the light source and the light source correction module are arranged on one side of the digestion module, and the detection module is arranged on the other side of the digestion module;

[0006] The light source correction module includes a collimator;

[0007] The digestion module comprises a digestion chamber, in which a digestion tube is arranged, and a liquid to be tested is placed in the digestion tube;

[0008] The detection module includes a focusing lens, a spectrometer, a filter and a photodetector;

[0009] The light beam is excited by the light source, collimated by the collimator and then passes through the digestion tube. After being absorbed by the liquid to be tested in the digestion tube, the light beam is divided into three paths by the focusing lens and the beam splitter. Finally, each light beam is converted into an electrical signal through a filter and a photodetector.

[0010] Preferably, the filter and the area around the photodetector are light-proof.

[0011] Preferably, an outer cover is provided at the detection module, and the outer cover is sealed and fixedly connected to the side wall of the digestion chamber to improve the sealing effect and thus improve the accuracy of the measurement.

[0012] Furthermore, the light source includes a xenon lamp or a deuterium lamp.

[0013] Preferably, a light shield is provided outside the light source to protect the xenon lamp (light source) and prevent the light source from being exposed, and the light shield is fixedly connected to the digestion chamber.

[0014] Furthermore, the collimator includes a collimating lens.

[0015] Further, the photodetector includes a phototube, which converts the optical signal into an electrical signal;

[0016] The detection module also includes a photodetector amplifying device, and the photodetector amplifying device includes a photomultiplier tube, and the photomultiplier tube is used to amplify the electrical signal.

[0017] Furthermore, coaxial placement holes are provided on both sides of the digestion chamber, which are used to place a collimator and a focusing lens respectively.

[0018] Furthermore, the beam splitter includes a first beam splitter and a second beam splitter, and the first beam splitter and the second beam splitter are arranged at 45 degrees.

[0019] Furthermore, the center points of the first beam splitter, the second beam splitter and the center axis of the focusing lens are on the same axis.

[0020] Furthermore, the beam splitter is a beam splitter.

[0021] Furthermore, the optical filter includes a first optical filter, a second optical filter and a third optical filter, the central wavelength of the first optical filter is 220nm, the central wavelength of the second optical filter is 275nm, and the central wavelength of the third optical filter is 880nm. The optical filter is domestically produced. This solution not only meets the national standard method requirement of testing total nitrogen using dual ultraviolet spectrophotometry to collect and analyze two wavelengths of 220nm and 275nm, but also solves the problem of complex optical path devices and high cost of practical imported filters in current total nitrogen online monitors.

[0022] The photoelectric detector can collect data at three wavelengths of 220nm, 275nm and 880nm. The photoelectric detector transmits the data to the MCU (single-chip microcomputer) through the ADC (analog-to-digital converter), communicates to the host computer, and displays the photovoltage.

[0023] Furthermore, the digestion chamber is also connected to a heat dissipation device to facilitate heat dissipation in the digestion chamber. The heat dissipation device can be a heat dissipation hole, a heat sink or an exhaust fan.

[0024] The top of the digestion tube is provided with an air vent, and the bottom is provided with a water inlet / drainage port, which is convenient for water injection and drainage.

[0025] The digestion tube is made of quartz glass, which can improve the light passing effect.

[0026] The utility model has the following beneficial effects:

[0027] (1) The utility model is based on the principle of photometry and combines the cut-off photovoltage algorithm of domestic filters to make the data performance comparable to that of imported filters and achieve good data linearity.

[0028] (2) The optical path structure of the utility model focuses the optical path. Under normal detection conditions, a lower light source current and a smaller amplification factor are used, thereby reducing the fluctuation of the light source itself and the noise caused by the photodetector amplification circuit. When domestic filters (combined with the cutoff photovoltage algorithm of domestic filters) are used, data stability can also be improved.

[0029] (3) The optical path of the utility model is focused, which avoids the light source's own photocurrent being adjusted too high, and can extend the attenuation period of the light source. There is no need to replace the light source during the use of the equipment.

[0030] (4) The optical path device of the total nitrogen online monitor provided by the utility model has the advantages of simple structure, small size, low cost, no mechanical moving parts, no subsequent maintenance problems, easy installation and use, etc. It not only meets the national standard method requirements for testing total nitrogen using dual ultraviolet spectrophotometry to collect and analyze two wavelengths of 220nm and 275nm, but also solves the problems of complex optical path devices and high cost of imported filters in current total nitrogen online monitors. At the same time, the addition of 880nm detection wavelength can deduct the influence of actual water sample turbidity. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the external structure of the utility model.

[0032] Figure 2 It is a schematic diagram of placement of the optical path device of the utility model.

[0033] Figure 3 It is a schematic diagram of the optical path of the light beam in the utility model.

[0034] Figure 4 It is a circuit diagram of the photoelectric detection circuit in the utility model.

[0035] Figure 5 It is a circuit diagram of the amplifier circuit in the utility model.

[0036] Figure 6 It is a structural schematic diagram of the optical splitter fixing frame in the utility model. DETAILED DESCRIPTION

[0037] The specific implementation methods of the utility model are described in detail below in conjunction with the accompanying drawings. It should be pointed out that the embodiments are only specific explanations of the utility model and should not be regarded as limitations of the utility model. The purpose of the embodiments is to enable those skilled in the art to better understand and reproduce the technical solutions of the utility model. The protection scope of the utility model shall still be based on the scope defined in the claims.

[0038] like Figure 1-3 As shown, the utility model provides an optical path structure for a total nitrogen online monitor, comprising a light source 1, a light source correction module 2, a digestion module 3 and a detection module 4, wherein the light source 1 and the light source correction module 2 are arranged on one side of the digestion module 3, and the detection module 4 is arranged on the other side of the digestion module 3;

[0039] The light source correction module 2 includes a collimator 21;

[0040] The digestion module 3 comprises a digestion chamber 31, a digestion tube 32 is provided in the digestion chamber 31, and the liquid to be tested is placed in the digestion tube 32;

[0041] The detection module 4 includes a focusing lens 41, a beam splitter 42, a filter 43 and a photodetector 44;

[0042] The light beam is excited by the light source 1, and is collimated by the collimator and then passes through the digestion tube 32. After being absorbed by the liquid to be tested in the digestion tube 32, the light beam is divided into three paths by the focusing lens 41 and the beam splitter 42. Finally, each light beam is converted into an electrical signal through the filter 43 and the photodetector 44.

[0043] Preferably, a plano-concave cylindrical mirror 6 may be provided between the digestion tube 32 and the focusing lens 41, and the plano-concave cylindrical mirror 6 is used to diverge the light in the radial direction of the digestion chamber and then focus it through the rear-end focusing lens.

[0044] Preferably, the filter 43 and the area around the photodetector 44 are light-proof.

[0045] Preferably, an outer cover 45 is provided at the detection module 4, and the outer cover 45 is sealed and fixedly connected to the side wall of the digestion chamber 31 to improve the sealing effect and further improve the measurement accuracy.

[0046] In some preferred embodiments, the light source 1 is one of the light sources that can excite ultraviolet light, including a xenon lamp 10, a deuterium lamp, etc.

[0047] All optical components are encapsulated in black, non-reflective plastic or metal materials to eliminate stray light interference.

[0048] Preferably, a light shield 11 is provided outside the light source 1 to protect the xenon lamp (light source) and prevent the light source from being exposed. The light shield 11 is fixedly connected to the digestion chamber 31 .

[0049] In some preferred embodiments, the collimator comprises a collimating lens.

[0050] In some preferred embodiments, the photodetector 44 includes a phototube D1, which converts the optical signal into an electrical signal; Figure 4 As shown, specifically, the photodetector 44 is provided with a photoelectric detection circuit, the anode of the phototube D1 of the photoelectric detection circuit is connected to the inverting input pin of the first amplifier U1, the non-inverting input pin of the first amplifier U1 is grounded, the negative power supply pin of the first amplifier U1 is connected to the first capacitor C6 and the second capacitor C5, and the first capacitor C6 and the second capacitor C5 are connected in parallel; the positive power supply pin of the first amplifier U1 is connected to the third capacitor C2 and the fourth capacitor C3, and the third capacitor C2 and the fourth capacitor C3 are connected in parallel; the anode of the phototube D1 is connected to one connection end of the switch group S1, and the other connection end of the switch group S1 is connected to the output pin of the first amplifier U1; the switch group S1 is also connected in parallel with the fifth capacitor; the switch group S1 includes a plurality of switches, each of which is connected to a resistor.

[0051] The detection module also includes a photodetector amplifying device, which includes a photomultiplier tube U2, and the photomultiplier tube U2 is used to amplify the electrical signal; specifically, Figure 5 As shown, the photodetector amplifier device is provided with an amplifier circuit, the inverting input pin of the photomultiplier tube U2 of the amplifier circuit is connected to the first resistor R6, the output pin of the photomultiplier tube U2 is connected to the second resistor R5, a sixth capacitor C4 is connected between the inverting input pin and the output pin of the photomultiplier tube U2, and the inverting input pin of the photomultiplier tube U2 is also connected to the third resistor R7. When the second resistor R7 is connected to the sixth capacitor C4, the photodetector amplifier device works.

[0052] In some preferred embodiments, coaxial placement holes 311 are provided on both sides of the digestion chamber 31, which are used to place a collimator and a focusing lens 41 respectively.

[0053] In some preferred embodiments, the beam splitter 42 includes a first beam splitter 421 and a second beam splitter 422 , and the first beam splitter 421 and the second beam splitter 422 are arranged at 45 degrees.

[0054] In some preferred embodiments, the center points of the first beam splitter 421 and the second beam splitter 422 and the center axis of the focusing lens are on the same axis.

[0055] In some preferred embodiments, the beam splitter 42 is a beam splitter.

[0056] like Figure 6 As shown, the spectrometer is fixed to the outer cover 45 by a spectrometer fixing frame 7, and the spectrometer fixing frame 7 includes a main body 71, and the main body is provided with a first placement groove 72 and a second placement groove 73 for placing the first spectrometer 421 and the second spectrometer 422, and the first placement groove 72 and the second placement groove 73 are set at 45 degrees; the main body 71 is also provided with a fixing hole 74, and the fixing frame is fixed to the outer cover 45 by fasteners and the fixing hole 74.

[0057] In some preferred solutions, the filter 43 includes a first filter 431, a second filter 432 and a third filter 433, the central wavelength of the first filter 431 is 220nm, the central wavelength of the second filter 432 is 275nm, and the central wavelength of the third filter 433 is 880nm. The filter 43 is made in China, and this solution not only meets the national standard method requirement of testing total nitrogen using dual ultraviolet spectrophotometry to collect and analyze two wavelengths of 220nm and 275nm, but also solves the problem of complex optical path devices and high cost of practical imported filters in current total nitrogen online monitors.

[0058] The photodetector 44 can collect data at three wavelengths of 220nm, 275nm and 880nm. The photodetector transmits the data to the MCU (single-chip microcomputer) through the ADC (analog-to-digital converter), communicates to the host computer, and displays the photovoltage.

[0059] In some preferred embodiments, the digestion chamber 31 is further connected to a heat dissipation device 5 to facilitate heat dissipation in the digestion chamber. The heat dissipation device 5 may be a heat dissipation hole, a heat sink or an exhaust fan.

[0060] The top of the digestion tube is provided with an air vent, and the bottom is provided with a water inlet / drainage port, which is convenient for water injection and drainage.

[0061] The digestion tube 32 is made of quartz glass, which can improve the light passing effect.

[0062] It should be noted that the technical features not described in detail in the present invention can be achieved by any existing technology.

[0063] Although the preferred embodiments of the present application have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

Claims

1. An optical path structure for a total nitrogen online monitor, It is characterized in that It includes a light source, a light source correction module, a digestion module and a detection module, wherein the light source and the light source correction module are arranged on one side of the digestion module, and the detection module is arranged on the other side of the digestion module; The light source correction module includes a collimator; The digestion module comprises a digestion chamber, in which a digestion tube is provided; The detection module includes a focusing lens, a spectrometer, a filter and a photodetector; The light beam is excited by the light source, collimated by the collimator and then passes through the digestion tube. After being absorbed by the liquid to be tested in the digestion tube, the light beam is divided into three paths by the focusing lens and the beam splitter. Finally, each light beam is converted into an electrical signal through a filter and a photodetector.

2. The optical path structure for the total nitrogen online monitor according to claim 1, It is characterized in that The light source includes a xenon lamp or a deuterium lamp.

3. The optical path structure for the total nitrogen online monitor according to claim 1, It is characterized in that The collimator includes a collimating lens.

4. The optical path structure for the total nitrogen online monitor according to claim 1, It is characterized in that The photodetector includes a phototube that converts an optical signal into an electrical signal.

5. The optical path structure for the total nitrogen online monitor according to claim 1, It is characterized in that Coaxial placement holes are arranged on both sides of the digestion chamber, which are used to place a collimator and a focusing lens respectively.

6. The optical path structure for the total nitrogen online monitor according to claim 1, It is characterized in that The beam splitter includes a first beam splitter and a second beam splitter, and the first beam splitter and the second beam splitter are arranged at 45 degrees.

7. The optical path structure for the total nitrogen online monitor according to claim 1, It is characterized in that The center points of the first beam splitter and the second beam splitter and the center axis of the focusing lens are on the same axis.

8. The optical path structure for the total nitrogen online monitor according to claim 6, It is characterized in that The beam splitter is a beam splitter.

9. The optical path structure for the total nitrogen online monitor according to claim 1, It is characterized in that The optical filters include a first optical filter, a second optical filter and a third optical filter. The central wavelength of the first optical filter is 220 nm, the central wavelength of the second optical filter is 275 nm, and the central wavelength of the third optical filter is 880 nm.

10. The optical path structure for the total nitrogen online monitor according to claim 1, It is characterized in that The digestion chamber is also connected with a heat dissipation device.

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