Online total nitrogen analyzer

Abstract

This application relates to the field of water quality analysis technology and discloses an online total nitrogen analyzer, which includes a reversible peristaltic pump, a quantitative device, a valve module, a digester, a xenon lamp, and a spectrometer. The valve module includes a first valve port, a second valve port, a sample valve, and an injection valve. The first valve port is connected to the second valve port, and the sample valve and injection valve are respectively connected to the first valve port. The peristaltic pump is connected to the quantitative device through a first pipe, the quantitative device is connected to the first valve port through a second pipe, and the injection valve is connected to the digester through a third pipe. The digester is equipped with a heater. The peristaltic pump is used to pump water samples from the sample valve into the quantitative device, and also to pump water samples from the quantitative device through the injection valve into the digester. The xenon lamp is used to emit detection light to the digester, and the spectrometer is used to receive the detection light after digestion. This application aims to solve the technical problem that water quality testing devices have poor detection accuracy and cannot accurately detect total nitrogen in wastewater.

Description

Technical Field

[0001] This application relates to the field of water quality analysis technology, and in particular to an online total nitrogen analyzer. Background Technology

[0002] Total nitrogen, especially nitrate and ammonia nitrogen, is a key nutrient for algal growth. Excessive total nitrogen input leads to frequent eutrophication in lakes, rivers, and coastal waters, causing harmful algal blooms (red tides, algal blooms), resulting in serious consequences such as decreased dissolved oxygen (fish deaths), water quality deterioration, ecosystem damage, and threats to drinking water sources. Therefore, monitoring total nitrogen in wastewater is particularly important in the process of environmental protection.

[0003] In related technologies, the accuracy of water quality testing devices decreases after a period of use, making it impossible to accurately detect total nitrogen in wastewater, which is not conducive to taking timely wastewater treatment measures. Utility Model Content

[0004] The purpose of this application is to provide an online total nitrogen analyzer, which aims to solve the technical problem that the detection accuracy of water quality testing devices decreases after a period of use, making it impossible to accurately detect total nitrogen in wastewater.

[0005] To achieve the above objectives, this application provides an online total nitrogen analyzer, which includes a reversible peristaltic pump, a quantitative device, a valve module, a digester, a xenon lamp, and a spectrometer. The valve module includes a first valve port, a second valve port, a sample valve, and an injection valve. The first valve port is connected to the second valve port, and the sample valve and the injection valve are respectively connected to the first valve port.

[0006] The peristaltic pump is connected to the metering device through a first pipe, the metering device is connected to the first valve port through a second pipe, and the injection valve is connected to the digester through a third pipe;

[0007] The digester is equipped with a heater, and the peristaltic pump is used to pump the water sample from the sample valve into the quantitative device. The peristaltic pump is also used to pump the water sample from the quantitative device through the injection valve into the digester. The xenon lamp is used to emit detection light to the digester, and the spectrometer is used to receive the detection light after passing through the digester.

[0008] Optionally, the online total nitrogen analyzer further includes a diluent and a dilution valve, wherein the dilution valve is connected to the second valve port via a fourth pipe, and the diluent is connected to the dilution valve via a fifth pipe.

[0009] Optionally, the online total nitrogen analyzer further includes a discharge valve assembly. The dilution valve has a common end, a normally closed end, and a normally open end. The common end of the dilution valve is connected to the second valve port through the fourth pipe. The normally closed end of the dilution valve is connected to the dilution valve through the fifth pipe. The normally open end of the dilution valve is connected to the discharge valve assembly.

[0010] Optionally, the discharge valve assembly includes a waste liquid discharge valve and a wastewater discharge valve. The waste liquid discharge valve has a common end, a normally closed end, and a normally open end. The common end of the waste liquid discharge valve is connected to the normally open end of the dilution valve. A waste liquid container is externally connected to the normally closed end of the waste liquid discharge valve. The normally open end of the waste liquid discharge valve is connected to the wastewater discharge valve, and a wastewater container is externally connected to the wastewater discharge valve.

[0011] Optionally, the online total nitrogen analyzer also includes an exhaust three-way valve;

[0012] The first end of the exhaust three-way valve is connected to the diluent, the second end of the exhaust three-way valve is connected to the digester, and the third end of the exhaust three-way valve is connected to the atmospheric environment.

[0013] Optionally, the heater includes a heating wire wound around the digester.

[0014] Optionally, the online total nitrogen analyzer further includes a cooling fan for cooling the digester.

[0015] Optionally, the digester is provided with a first high-pressure valve and a second high-pressure valve, the second end of the exhaust three-way valve is connected to the digester through the first high-pressure valve, and the third pipeline is connected to the digester through the second high-pressure valve.

[0016] Optionally, the valve assembly module further includes a pure water valve, which is connected to the first valve port.

[0017] Optionally, the valve assembly module further includes multiple reagent valves, each of which is connected to the first valve port.

[0018] This application provides an online total nitrogen analyzer, which has the following advantages:

[0019] The online total nitrogen analyzer includes a peristaltic pump, a quantitative device, a valve module, a digester, a xenon lamp, and a spectrometer. To use the analyzer, open the sample valve, close the injection valve and other valves in the valve module, and start the peristaltic pump to pump the wastewater sample into the quantitative device for quantification. After quantification, close the sample valve, open the injection valve, and the peristaltic pump reverses direction, pumping the sample from the quantitative device through the injection valve into the digester. Start the heater inside the digester for high-temperature heating, causing the sample to digest within the digester. After digestion, turn on the xenon lamp to emit detection light into the digester. The detection light passes through the sample in the digester, and the spectrometer receives the detected light, performs detection according to the set integration time, and outputs the detection result to the terminal device. The terminal device then uses its set program and stored calibration curve to obtain the total nitrogen content value of the water sample.

[0020] This application replaces ultraviolet lamps with xenon lamps and photodiodes with spectrometers. Xenon lamps have a longer lifespan than ultraviolet lamps, can emit light waves with a wider wavelength range, and are more stable. Spectrometers can receive light waves in longer wavelength bands and have higher detection accuracy than traditional photodiode detectors, thereby improving the accuracy of total nitrogen detection in wastewater. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the structure of the online total nitrogen analyzer provided in the embodiments of this application;

[0023] Figure 2 Another schematic diagram of the total nitrogen online analyzer provided in the embodiments of this application;

[0024] Figure 3 This is a schematic diagram of the total nitrogen online analyzer provided in an embodiment of this application.

[0025] The markings in the image are as follows:

[0026] 1. Peristaltic pump; 2. Quantitative device; 3. Valve assembly module; 31. First valve port; 32. Second valve port; 33. Sample valve; 34. Injection valve; 35. Pure water valve; 36. Reagent valve; 4. Digester; 5. Xenon lamp; 6. Spectrometer; 7. First pipeline; 8. Second pipeline; 9. Third pipeline; 10. Diluter; 11. Dilution valve; 12. Fourth pipeline; 13. Fifth pipeline; 14. Discharge valve assembly; 141. Waste liquid discharge valve; 142. Wastewater discharge valve; 15. Exhaust three-way valve; 16. Heating wire; 17. Cooling fan; 18. First high-pressure valve; 19. Second high-pressure valve. Detailed Implementation

[0027] The specific embodiments of this application will be described in further detail below with reference to the accompanying drawings and examples. The following examples are used to illustrate this application, but are not intended to limit the scope of this application.

[0028] In the description of this application, it should be noted that the terms "upper", "lower", "front", "rear", "inner", "outer", etc. used in this application to indicate the orientation or positional relationship are based on the positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and are not intended to indicate or imply that the device and element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0029] In the description of this application, it should be understood that the terms "first," "second," etc., are used to describe various types of information, but these terms are not limited to them and are only used to distinguish information of the same type from one another. For example, without departing from the scope of this application, "first" information may also be referred to as "second" information, and similarly, "second" information may also be referred to as "first" information.

[0030] In related technologies, total nitrogen (TNO) refers to the total amount of all nitrogen-containing compounds in a water sample. TNO comprehensively reflects the degree of nitrogen pollution in water bodies and is a key indicator for assessing water quality, determining the risk of eutrophication, and monitoring environmental pollution. TNO is the main nutrient source for algae growth. When the TNO concentration in water is too high, algae will proliferate in large quantities, consuming dissolved oxygen, leading to black and smelly water, fish deaths, and even the formation of "dead water zones."

[0031] Currently, the total nitrogen concentration (TNC) value is quantitatively converted from absorbance at specific ultraviolet wavelengths (220 nm and 275 nm) after digestion by detecting the absorbance of the water sample at specific ultraviolet wavelengths (220 nm and 275 nm), then using dual-wavelength correction to subtract interference, and finally based on the calibration curve. Conventional TNC detection methods use ultraviolet lamps and photodiode detectors. However, due to the weak light and short lifespan of ultraviolet lamps, and the insufficient detection range of photodiodes, the accuracy of TNC detection is affected.

[0032] like Figures 1 to 3As shown in the embodiment of this application, an online total nitrogen analyzer is provided, including a reversible peristaltic pump 1, a quantitative device 2, a valve module 3, a digester 4, a xenon lamp 5, and a spectrometer 6. The valve module 3 includes a first valve port 31, a second valve port 32, a sample valve 33, and an injection valve 34. The first valve port 31 is connected to the second valve port 32, and the sample valve 33 and the injection valve 34 are respectively connected to the first valve port 31. The peristaltic pump 1 is connected to the quantitative device 2 through a first pipe 7, the quantitative device 2 is connected to the first valve port 31 through a second pipe 8, and the injection valve 34 is connected to the digester 4 through a third pipe 9. The digester 4 is equipped with a heater. The peristaltic pump 1 is used to pump water samples from the sample valve 33 into the quantitative device 2, and also to pump water samples from the quantitative device 2 through the injection valve 34 into the digester 4. The xenon lamp 5 is used to emit detection light to the digester 4, and the spectrometer 6 is used to receive the detection light after digestion by the digester 4.

[0033] In this embodiment, the peristaltic pump 1 rotates forward or reverse under different control commands. When the peristaltic pump 1 rotates forward, it pumps the solution from the valve group module 3 into the metering device 2. When the peristaltic pump 1 rotates in reverse, it pumps the solution from the metering device 2 into the valve group module 3.

[0034] For example, valve module 3 is an eight-way valve or an eight-way valve combination with eight independent control channels or functional modules. Sample valve 33 and injection valve 34 are two of these valves, and either valve can be opened to connect it to the system pipeline.

[0035] Digester 4 is a chemical digestion device that uses high temperature and high pressure or high temperature reflux to convert organic matter and reducing substances (such as nitrite and sulfides) in water samples into measurable forms. In this embodiment, digester 4 is used to digest total nitrogen in water samples and convert it into nitrate nitrogen.

[0036] Based on the above technical solution, sample valve 33 is opened, injection valve 34 and other valves in valve group module 3 are closed, peristaltic pump 1 is started, and peristaltic pump 1 rotates forward to pump the wastewater sample to be tested (hereinafter referred to as water sample) from the first valve port 31 into the quantitative device 2, where quantitative analysis is performed. After quantitative analysis is completed, sample valve 33 is closed, injection valve 34 is opened, and peristaltic pump 1 rotates in reverse to pump the water sample from the quantitative device 2 through injection valve 34 into digester 4. The heater inside digester 4 is started to heat the water sample at high temperature, causing the water sample to digest within digester 4. After digestion, xenon lamp 5 is turned on to emit detection light to digester 4. The detection light passes through the water sample in digester 4, and spectrometer 6 receives the detected light, performs detection according to the set integration time, and outputs the detection result to terminal equipment. The total nitrogen content value of the water sample is obtained through the set program and stored calibration curve of the terminal equipment.

[0037] In practical applications, ultraviolet (UV) lamps can only emit specific short wavelengths. To detect the total nitrogen content of a water sample by measuring its absorbance at specific wavelengths of 220nm and 275nm, two sets of UV lamps are required, complicating the water quality analyzer's structure. In this embodiment, a xenon lamp 5 replaces the UV lamp, and a spectrometer 6 replaces the photodiode. The xenon lamp 5 has a longer lifespan than the UV lamp and can emit long wavelengths of 100-1000nm. The spectrometer 6 scans the entire 100-1000nm wavelength range, accurately subtracting interference from other wavelengths, and measures the total nitrogen content at dual wavelengths of 220nm and 275nm. An algorithm eliminates interference from dissolved organic matter. The spectrometer 6 uses a grating or prism for spectral dispersion, achieving a spectral resolution of ±0.1nm. It accurately captures the narrow absorption peak of nitrate (220nm), offering higher detection accuracy than traditional photodiode detectors and effectively improving the accuracy of total nitrogen detection in wastewater.

[0038] In some embodiments, such as Figure 3 As shown, the online total nitrogen analyzer also includes a diluent 10 and a dilution valve 11. The dilution valve 11 is connected to the second valve port 32 through the fourth pipe 12, and the diluent 10 is connected to the dilution valve 11 through the fifth pipe 13.

[0039] Specifically, because some water samples have high nitrogen content and turbidity, the detection light cannot pass through smoothly and be effectively received by the spectrometer 6. Therefore, before pumping the water sample into the digester 4, the dilution valve 11 is opened, and the peristaltic pump 1 pumps the water sample from the metering device 2 into the diluent 10. Pure water is then pumped into the diluent 10 to dilute the water sample. The peristaltic pump 1 then pumps the water sample back from the diluent 10 to the metering device 2. The dilution valve 11 is then closed, and the injection valve 34 is opened. The peristaltic pump 1 reverses direction and pumps the water sample from the metering device 2 through the injection valve 34 into the digester 4. At this point, the diluted water sample can pass through the detection light, allowing the spectrometer 6 to receive the detection light.

[0040] When the water sample concentration is too high, the light transmittance is too poor, and the spectrometer 6 cannot detect accurately, requiring manual dilution of the water sample, which is quite troublesome. This embodiment sets up a diluent 10. After the water sample is injected into the diluent 10 through the dilution valve 11, pure water is added for dilution. The diluted water sample is then injected into the digester 4 for detection. Therefore, by setting up the diluent 10 and the dilution valve 11, it is equivalent to adding a water sample dilution device. When the water sample cannot be detected, it is diluted first to meet the detection requirements, thereby increasing the total nitrogen detection range and adapting to the needs of wastewater detection.

[0041] In some embodiments, such as Figure 3 As shown, the valve group module 3 also includes a pure water valve 35, which is connected to the first valve port 31.

[0042] Specifically, before pumping the water sample to be tested into the digester 4, the system's pipes and devices are cleaned to prevent other impurities from entering and affecting the testing results. During cleaning, the pure water valve 35 is opened, and the other valves in the valve group module 3 are closed. The peristaltic pump 1 is started, and the peristaltic pump 1 rotates forward to pump the pure water from the valve group module 3 into the metering device 2. After metering in the metering device 2, the pure water valve 35 is closed, and the peristaltic pump 1 rotates in reverse to pump the pure water from the metering device 2 through the valve group module 3 into the digester 4, thereby cleaning the digester 4 and the system pipes. After cleaning, the solution is drained, and then the sample valve 33 is opened, and the peristaltic pump 1 is started to pump the water sample into the digester 4 to carry out the above-mentioned water sample digestion reaction process.

[0043] In some embodiments, such as Figure 3 As shown, the valve group module 3 also includes multiple reagent valves 36, which are respectively connected to the first valve port 31.

[0044] For example, valve module 3 is an eight-way valve, including a sample valve 33, an injection valve 34, a pure water valve 35, a standard solution valve, and four reagent valves 36. The four reagent valves 36 are designated as the first reagent valve, the second reagent valve, the third reagent valve, and the fourth reagent valve. Before the digestion reaction, the first reagent valve is opened, and a peristaltic pump 1 pumps potassium persulfate solution into the digester 4 to mix with the water sample. After the digestion reaction is complete, the second reagent valve is opened, and a peristaltic pump 1 pumps hydrochloric acid solution into the digester 4 to mix with the water sample, adjusting the solution acidity for total nitrogen detection.

[0045] In some embodiments, such as Figure 3 As shown, the total nitrogen online analyzer also includes a discharge valve group 14. The dilution valve 11 has a common end, a normally closed end and a normally open end. The common end of the dilution valve 11 is connected to the second valve port 32 through the fourth pipe 12. The normally closed end of the dilution valve 11 is connected to the diluter 10 through the fifth pipe 13. The normally open end of the dilution valve 11 is connected to the discharge valve group 14.

[0046] Specifically, dilution valve 11 is an electromagnetic three-way valve. Both the normally closed and normally open ends of dilution valve 11 are closed, and the second valve port 32 is not connected to dilution valve 11 at this time. When diluting the water sample, under the controller's command, the normally closed end of dilution valve 11 is opened, and the normally open end is closed. The peristaltic pump 1 pumps the water sample and pure water from the metering device 2 into the diluter 10 to dilute the water sample. After the test is completed, under the controller's command, the normally closed end of dilution valve 11 is closed, and the normally open end is opened. The wastewater sample solution enters the discharge valve group 14 from the dilution valve 11 and is discharged through the discharge valve group 14.

[0047] In some embodiments, such as Figure 3As shown, the discharge valve assembly 14 includes a waste liquid discharge valve 141 and a wastewater discharge valve 142. The waste liquid discharge valve 141 has a common end, a normally closed end, and a normally open end. The common end of the waste liquid discharge valve 141 is connected to the normally open end of the dilution valve 11. A waste liquid container is connected to the normally closed end of the waste liquid discharge valve 141. The normally open end of the waste liquid discharge valve 141 is connected to the wastewater discharge valve 142. A wastewater container is connected to the wastewater discharge valve 142.

[0048] In this embodiment, waste liquid discharge valve 141 is used to discharge the water sample solution after the reaction, and wastewater discharge valve 142 is used to discharge the pure aqueous solution after cleaning.

[0049] Specifically, after the cleaning system, the normally closed end of the waste liquid discharge valve 141 is closed, and the normally open end is open. The pure water cleaning solution passes through the waste liquid discharge valve 141 into the wastewater discharge valve 142, and is then discharged from the wastewater discharge valve 142 into a wastewater container for collection. After digestion, under the command of the controller, the normally closed end of the waste liquid discharge valve 141 is opened, and its normally open end is closed. The wastewater sample solution is discharged from the waste liquid discharge valve 141 into the waste liquid container for collection. The wastewater sample solution is then treated to meet the required standards before being discharged.

[0050] In this embodiment, the waste liquid discharge valve 141 and wastewater discharge valve 142 can be used to collect and treat pure aqueous solution and sewage sample solution separately, thereby reducing the amount of high-concentration waste liquid collected and lowering the cost of sewage treatment.

[0051] In some embodiments, such as Figure 3 As shown, the online total nitrogen analyzer also includes an exhaust three-way valve 15; the first end of the exhaust three-way valve 15 is connected to the diluent 10, the second end of the exhaust three-way valve 15 is connected to the digester 4, and the third end of the exhaust three-way valve 15 is connected to the atmospheric environment.

[0052] Specifically, the exhaust three-way valve 15 is a physical three-way valve, that is, the first end, the second end and the third end of the exhaust three-way valve 15 are connected. By setting the exhaust three-way valve 15, the diluent 10 and the digester 4 are connected to the atmosphere, maintaining the differential pressure balance of the system pipeline, so that the water sample can be pumped into the diluent 10 or the digester 4 before the dilution or digestion reaction.

[0053] In some embodiments, such as Figure 3 As shown, the heater includes a heating wire 16, which is wound around the digester 4. The heating wire 16 is used to heat the water sample inside the digester 4. The winding position of the heating wire 16 avoids the detection light path of the xenon lamp 5 and the spectrometer 6, so as to avoid blocking the propagation path of the detection light.

[0054] In some embodiments, such as Figure 3As shown, the online total nitrogen analyzer also includes a cooling fan 17, which is used to cool the digester 4.

[0055] Specifically, after digestion is completed, digester 4 remains at a high temperature. Cooling air is blown onto digester 4 by cooling fan 17 to cool digester 4 and accelerate the cooling of digester 4.

[0056] In some embodiments, such as Figure 3 As shown, the digester 4 is equipped with a first high-pressure valve 18 and a second high-pressure valve 19. The second end of the exhaust three-way valve 15 is connected to the digester 4 through the first high-pressure valve 18, and the third pipe 9 is connected to the digester 4 through the second high-pressure valve 19.

[0057] For example, the first high-pressure valve 18 is located at the top of the digester 4, and the second high-pressure valve 19 is located at the bottom of the digester 4. Before the digestion reaction, the first high-pressure valve 18 and the second high-pressure valve 19 are opened to connect the digester 4 to the system pipeline and to the atmospheric environment through the exhaust three-way valve 15. Before the digestion reaction, the water sample is pumped into the digester 4 through the second high-pressure valve 19. Then, the first high-pressure valve 18 and the second high-pressure valve 19 are closed, and the heating wire 16 is activated to heat the water sample, causing the water sample to undergo a digestion reaction under high temperature and high pressure conditions.

[0058] In one specific embodiment, the process for total nitrogen detection is as follows:

[0059] First, open sample valve 33, and peristaltic pump 1 rotates forward to draw water sample into quantitative device 2 for quantitative measurement. Close sample valve 33, open injection valve 34, and peristaltic pump 1 rotates in reverse to pump water sample into digester 4. After completion, close injection valve 34.

[0060] Second, open the first reagent valve, and the peristaltic pump 1 rotates forward to draw potassium persulfate into the quantitative device 2 for quantitative measurement. Close the first reagent valve, open the injection valve 34 to add potassium persulfate into the digester 4, and close the injection valve 34 after completion. Turn on the heater to heat the water sample at high temperature in the digester 4 to digest it, and then cool it after digestion.

[0061] Third, open the second reagent valve, and the peristaltic pump 1 rotates forward to draw hydrochloric acid solution into the quantitative device 2 for quantitative measurement. Close the second reagent valve, open the injection valve 34 to add hydrochloric acid solution into the digester 4 to adjust the pH, and then close the injection valve 34 after completion.

[0062] Fourth, the spectrometer 6 and xenon lamp 5 are controlled to detect water samples at wavelengths of 220nm and 275nm. The water sample calibration absorbance value is obtained through an algorithm, and the total nitrogen concentration of the water sample is calculated based on the calibration curve stored in the system.

[0063] It should be understood that the term "and / or" as used in this specification and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes such combinations. It should be noted that, herein, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or system. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or system that includes that element.

[0064] The sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments. The above descriptions are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An online total nitrogen analyzer, characterized in that, It includes a reversible peristaltic pump, a metering device, a valve module, a digester, a xenon lamp, and a spectrometer. The valve module includes a first valve port, a second valve port, a sample valve, and an injection valve. The first valve port is connected to the second valve port, and the sample valve and the injection valve are respectively connected to the first valve port. The peristaltic pump is connected to the metering device through a first pipe, the metering device is connected to the first valve port through a second pipe, and the injection valve is connected to the digester through a third pipe; The digester is equipped with a heater, and the peristaltic pump is used to pump the water sample from the sample valve into the quantitative device. The peristaltic pump is also used to pump the water sample from the quantitative device into the digester through the injection valve. The xenon lamp is used to emit detection light to the digester, and the spectrometer is used to receive the detection light after passing through the digester.

2. The online total nitrogen analyzer according to claim 1, characterized in that, The online total nitrogen analyzer also includes a diluter and a diluter valve. The diluter valve is connected to the second valve port through a fourth pipe, and the diluter is connected to the diluter valve through a fifth pipe.

3. The online total nitrogen analyzer according to claim 2, characterized in that, The online total nitrogen analyzer also includes a discharge valve assembly. The dilution valve has a common end, a normally closed end, and a normally open end. The common end of the dilution valve is connected to the second valve port through the fourth pipe. The normally closed end of the dilution valve is connected to the dilution valve through the fifth pipe. The normally open end of the dilution valve is connected to the discharge valve assembly.

4. The online total nitrogen analyzer according to claim 3, characterized in that, The discharge valve assembly includes a waste liquid discharge valve and a wastewater discharge valve. The waste liquid discharge valve has a common end, a normally closed end, and a normally open end. The common end of the waste liquid discharge valve is connected to the normally open end of the dilution valve. A waste liquid container is connected to the normally closed end of the waste liquid discharge valve. The normally open end of the waste liquid discharge valve is connected to the wastewater discharge valve, and a wastewater container is connected to the wastewater discharge valve.

5. The online total nitrogen analyzer according to claim 3, characterized in that, The online total nitrogen analyzer also includes an exhaust three-way valve; The first end of the exhaust three-way valve is connected to the diluent, the second end of the exhaust three-way valve is connected to the digester, and the third end of the exhaust three-way valve is connected to the atmospheric environment.

6. The online total nitrogen analyzer according to claim 1, characterized in that, The heater includes a heating wire wound around the digester.

7. The online total nitrogen analyzer according to claim 1, characterized in that, The online total nitrogen analyzer also includes a cooling fan for cooling the digester.

8. The online total nitrogen analyzer according to claim 5, characterized in that, The digester is equipped with a first high-pressure valve and a second high-pressure valve. The second end of the exhaust three-way valve is connected to the digester through the first high-pressure valve, and the third pipeline is connected to the digester through the second high-pressure valve.

9. The online total nitrogen analyzer according to claim 1, characterized in that, The valve group module also includes a pure water valve, which is connected to the first valve port.

10. The online total nitrogen analyzer according to any one of claims 1 to 9, characterized in that, The valve group module also includes multiple reagent valves, each of which is connected to the first valve port.

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