System and method for online monitoring of water quality with small flow rate

Abstract

The present invention discloses a system and method for online monitoring of micro-flow water quality. The system includes a fluid storage module, a digestion and measurement module, a rotary cut valve and a pump body. The fluid storage module is formed with a carrier liquid storage chamber, a water sample storage chamber and at least one reagent storage chamber; the first common interface of the rotary cut valve is connected to the carrier liquid storage chamber through a hose, the water sample selection interface of the rotary cut valve is connected to the water sample storage chamber, the measurement selection interface of the rotary cut valve is connected to the first interface of the digestion and measurement module, at least one reagent selection interface of the rotary cut valve corresponds to at least one reagent storage chamber, and the reagent selection interface is connected to the corresponding reagent storage chamber; the pump body is used to drive the flow of fluid in the hose, wherein, during the process of the water sample or reagent being extracted into the hose, the connection between the hose and the pump body always has carrier liquid. The technical solution of the present invention can improve the accuracy of the volume of the extracted water sample or reagent and ensure the accuracy of quantitative analysis.

Description

Technical Field

[0001] The present invention relates to the technical field of water quality monitoring, and in particular to a system and method for online monitoring of micro-flow water quality. Background Art

[0002] Water quality testing helps us understand the level of pollutants in water, assess water quality, and promptly identify and resolve water pollution issues, thereby protecting the ecological environment and public health. In water quality monitoring, parameters such as chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP) are important indicators of the degree of water pollution. Real-time and accurate measurement of these parameters helps environmental protection departments and related businesses take timely measures to reduce pollutant emissions, ensuring the sustainable use of water resources and maintaining a balanced ecosystem.

[0003] In the exemplary technology, the online water quality monitoring system uses a peristaltic pump to drive water samples and reagents to flow in the pipeline, and perform corresponding reactions and detections. However, this method has some significant disadvantages when extracting a specific volume of water samples or reagents. Since the working principle of the peristaltic pump is to move the fluid by mechanically squeezing the pipeline, there will be air in the internal area where the pipeline contacts the peristaltic pump. During the process of the peristaltic pump squeezing the pipeline, due to the squeezing and releasing action of the pipeline, a small air flow will be generated at the position where the pipeline is squeezed. This air flow will cause small fluctuations and changes in the volume of the fluid. This fluctuation will cause the volume of the water sample or reagent to be inaccurate, and the accuracy of the quantitative analysis cannot be guaranteed.

[0004] It should be noted that the exemplary technologies mentioned here are only for ease of understanding and do not constitute an admission that they are prior arts. Summary of the Invention

[0005] The main purpose of the present invention is to solve the technical problem that in the existing water quality monitoring, when extracting water samples or reagents, the extracted volume is inaccurate and the accuracy of quantitative analysis cannot be guaranteed.

[0006] A first aspect of the present invention provides a micro-flow water quality online monitoring system, which includes a fluid storage module, a digestion and measurement module, a rotary cutting valve, and a pump body;

[0007] The fluid storage module is formed with a carrier liquid storage chamber, a water sample storage chamber and at least one reagent storage chamber;

[0008] The digestion measurement module is formed with a digestion reaction chamber, a first interface and a second interface, wherein the digestion reaction chamber is communicated with the first interface and the second interface respectively;

[0009] The rotary cutting valve includes a first common interface, a water sample selection interface, a measurement selection interface, a gas selection interface, a waste selection interface and at least one reagent selection interface. The first common interface is connected to the carrier liquid storage cavity through a hose, the water sample selection interface is connected to the water sample storage cavity, the measurement selection interface is connected to the first interface, the at least one reagent selection interface corresponds to the at least one reagent storage cavity one by one, and the reagent selection interface is connected to the corresponding reagent storage cavity;

[0010] The pump body is provided on the hose, and the pump body is used to drive the fluid in the hose to flow from the first common interface toward the direction close to the carrier liquid storage chamber, so as to extract the water sample in the water sample storage chamber, the reagent in the reagent storage chamber, or the gas at the gas selection interface into the hose. The pump body is also used to drive the fluid in the hose to flow from the carrier liquid storage chamber toward the direction close to the first common interface, so as to extract the carrier liquid in the carrier liquid storage chamber into the hose; wherein,

[0011] During the process of drawing water samples or reagents into the flexible pipe, the connection between the flexible pipe and the pump body always has carrier fluid.

[0012] Optionally, the hose is made of transparent material, and a liquid detection sensor is provided on the portion of the hose located between the pump body and the first common interface. The liquid detection sensor is used to detect the presence of liquid in the hose, and the liquid presence status includes the presence of liquid and the absence of liquid.

[0013] Optionally, the number of the liquid detection sensors is at least two, and the at least two liquid detection sensors are arranged at intervals.

[0014] Optionally, the micro-flow water quality online monitoring system includes a first three-way valve, and the first three-way valve includes a first selection interface, a second selection interface and a second common interface;

[0015] The hose includes a first pipe section, a second pipe section, and a third pipe section, the first pipe section is connected to the first common interface and the second common interface respectively, and the pump body is provided on the first pipe section;

[0016] The second pipe section is communicated with the first selection interface and the carrier liquid storage chamber respectively, and the third pipe section is communicated with the second selection interface and the gas outside the micro-flow water quality online monitoring system respectively.

[0017] Optionally, a first valve body structure is provided between the first interface and the measurement selection interface, and a second valve body structure is provided between the second interface; and / or,

[0018] The rotary cutting valve includes at least one reserved selection interface; and / or,

[0019] The fluid storage module also includes a span verification fluid storage chamber and a range calibration fluid storage chamber, the rotary cut valve includes a function selection interface, the micro-flow water quality online monitoring system includes a second three-way valve, the second three-way valve includes a third selection interface, a fourth selection interface and a third common interface, the third selection interface is connected to the span verification fluid storage chamber, the fourth selection interface is connected to the range calibration fluid storage chamber, and the third common interface is connected to the function selection interface.

[0020] Optionally, the digestion measurement module includes a digestion tube, a measurement transmitter and a measurement receiver, and the digestion tube is formed with the digestion reaction chamber, the first interface and the second interface;

[0021] The measurement transmitter and the measurement receiver are respectively arranged on two opposite sides of the digestion tube;

[0022] The measuring transmitter includes a shell and a light-emitting element arranged on the shell. The shell forms a measuring light channel. The diameter of the measuring light channel is smaller than the inner diameter of the digestion tube. The light emitted by the light-emitting element is guided through the measuring light channel to illuminate the digestion tube. The measuring receiver is used to receive the light passing through the digestion tube.

[0023] Optionally, the inner diameter of the digestion tube is greater than or equal to 6 mm and less than or equal to 10 mm;

[0024] The diameter of the measuring light channel is greater than 0 mm and less than or equal to 0.8 mm.

[0025] A second aspect of the present invention provides a method for online monitoring of water quality at a low flow rate, comprising:

[0026] Switch the rotary cutting valve to the waste selection interface, and drive the carrier liquid in the carrier liquid storage chamber to flow to the waste selection interface through the pump body;

[0027] Switch the rotary cutting valve to the gas selection interface, and drive the gas outside the rotary cutting valve to flow into the hose through the pump body, so that the hose contains carrier liquid and gas; wherein the connection between the pump body and the hose contains carrier liquid;

[0028] Switch the rotary cutting valve to the water sample selection interface, and drive the water sample in the water sample storage chamber to flow into the hose through the pump body. During the flow of the water sample, the connection between the pump body and the hose always has carrier liquid;

[0029] Switch the rotary cutting valve to the reagent selection interface, and drive the reagent in the reagent storage chamber to flow into the hose through the pump body. During the flow of the reagent, the connection between the pump body and the hose always has carrier liquid;

[0030] The rotary cutting valve is switched to the measurement selection interface, and the water sample and reagent in the hose are driven to flow into the digestion reaction chamber through the pump body.

[0031] Optionally, switching the rotary cutting valve to a gas selection interface, and driving the gas outside the rotary cutting valve to flow into the hose through the pump body, includes:

[0032] Connecting the gas selection interface to the gas storage chamber to heat the gas in the gas storage chamber to a first preset temperature;

[0033] The rotary cutting valve is switched to the gas selection interface, and the heated gas in the gas storage chamber is driven to flow into the hose through the pump body, and the heated gas is allowed to stay in the hose for a first preset time.

[0034] Optionally, the first preset duration is calculated by the following formula:

[0035] ;

[0036] in, is the first preset duration, is the convective heat transfer coefficient, is the surface area of ​​the gas region in the hose, is the initial temperature of the gas when it enters the hose, is the ambient temperature, The temperature difference required to dry the carrier fluid on the hose wall.

[0037] The micro-flow water quality online monitoring system of the present invention effectively solves the problem of inaccurate capacity caused by air mixing in the prior art by always keeping the carrier liquid at the connection between the hose and the pump body. Specifically, the presence of the carrier liquid ensures that the squeezed part of the hose is always filled with liquid when the pump body is working. This feature ensures the airtightness inside the hose and prevents air from entering the pipeline. When the pump body drives the fluid, since there is carrier liquid inside the hose squeezed by the pump body, air cannot flow from the port on the hose away from the first common interface into the hose, and then flow in the direction close to the first common interface inside the hose. Therefore, the air volume inside the pipe section of the hose from the pump body to the first common interface is constant and does not change. This design ensures that when extracting water samples or reagents, external air will not enter the pipe section where the water samples and reagents flow, thereby avoiding volume fluctuations and inaccuracies caused by the flow of air. This airtight design ensures that the extraction capacity of water samples and reagents is always stable and accurate, effectively overcoming the capacity error problem caused by air flow in traditional peristaltic pump systems, significantly improving the accuracy of quantitative delivery of water samples and reagents, and ensuring the reliability and accuracy of subsequent test results. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0039] Figure 1 This is a structural diagram of an embodiment of a system for online monitoring of water quality with a small flow rate according to the present invention;

[0040] Figure 2 for Figure 1 A cross-sectional schematic diagram of an embodiment of a digestion measurement module;

[0041] Figure 3 for Figure 1 A cross-sectional schematic diagram of another embodiment of the digestion measurement module;

[0042] Figure 4 Schematic diagram of an embodiment of a method for online monitoring of water quality at a low flow rate according to the present invention.

[0043] Description of Figure Numbers:

[0044] 1. Fluid storage module; 11. Carrier liquid storage chamber; 12. Water sample storage chamber; 13. Reagent storage chamber; 14. Span verification liquid storage chamber; 15. Span calibration liquid storage chamber; 16. Gas storage chamber; 2. Digestion measurement module; 21. Digestion tube; 211. Digestion reaction chamber; 22. First interface; 23. Second interface; 24. First valve body structure; 25. Second valve body structure; 26. Measurement transmitter; 261. Housing; 261a. Measurement light channel; 262. Light emitting element; 263. Lens; 27. Measurement receiver; 28. Reference receiver; 3. Rotary cut valve; 3 1. First common interface; 32. Water sample selection interface; 33. Measurement selection interface; 34. Gas selection interface; 35. Waste selection interface; 36. Reagent selection interface; 37. Reserved selection interface; 38. Function selection interface; 4. Pump body; 5. Hose; 51. First pipe section; 52. Second pipe section; 53. Third pipe section; 6. Liquid detection sensor; 7. First three-way valve; 71. First selection interface; 72. Second selection interface; 73. Second common interface; 8. Second three-way valve; 81. Third selection interface; 82. Fourth selection interface; 83. Third common interface.

[0045] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0046] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0047] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), such directional indications are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0048] In addition, the descriptions of "first", "second", etc. in the present invention are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, "and / or" in the full text includes three solutions. Taking A and / or B as an example, it includes technical solution A, technical solution B, and technical solution that satisfies both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, and must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0049] The present invention provides a micro-flow water quality online monitoring system.

[0050] In the embodiment of the present invention, Figures 1 to 3 As shown, the micro-flow water quality online monitoring system includes a fluid storage module 1, a digestion and measurement module 2, a rotary cutting valve 3 and a pump body 4;

[0051] The fluid storage module 1 is formed with a carrier liquid storage chamber 11, a water sample storage chamber 12 and at least one reagent storage chamber 13;

[0052] The digestion measurement module 2 is formed with a digestion reaction chamber 211, a first interface 22 and a second interface 23, and the digestion reaction chamber 211 is communicated with the first interface 22 and the second interface 23 respectively;

[0053] The rotary cutting valve 3 includes a first common interface 31, a water sample selection interface 32, a measurement selection interface 33, a gas selection interface 34, a waste selection interface 35 and at least one reagent selection interface 36. The first common interface 31 is connected to the carrier liquid storage chamber 11 through a hose 5, the water sample selection interface 32 is connected to the water sample storage chamber 12, the measurement selection interface 33 is connected to the first interface 22, and at least one reagent selection interface 36 corresponds to at least one reagent storage chamber 13. The reagent selection interface 36 is connected to the corresponding reagent storage chamber 13;

[0054] The pump body 4 is provided on the hose 5. The pump body 4 is used to drive the fluid in the hose 5 to flow from the first common interface 31 toward the direction close to the carrier liquid storage chamber 11, so as to extract the water sample in the water sample storage chamber 12, the reagent in the reagent storage chamber 13, or the gas at the gas selection interface 34 into the hose 5. The pump body 4 is also used to drive the fluid in the hose 5 to flow from the carrier liquid storage chamber 11 toward the direction close to the first common interface 31, so as to extract the carrier liquid in the carrier liquid storage chamber 11 into the hose 5; wherein,

[0055] During the process of drawing the water sample or reagent into the hose 5 , the connection between the hose 5 and the pump body 4 always has carrier fluid.

[0056] In this embodiment, the fluid storage module 1 is used to store a variety of liquids and gases. It can include multiple independent storage structures, such as multiple storage bottles, etc. Each storage structure is formed with a cavity. It can also be separated into multiple cavities by a plate or other structure inside a shell structure. For easy distinction, each cavity is named based on the type of liquid or gas stored in the cavity, namely, the carrier liquid storage cavity 11, the water sample storage cavity 12 and the reagent storage cavity 13. The liquid or gas in each cavity can be added manually or by machine equipment, and there is no specific limitation here. In specific implementation, the carrier liquid is a liquid that does not chemically react with the hose 5. It can be high-purity water, deionized water, a buffer solution or an antibacterial solution, etc.

[0057] In the digestion reaction chamber 211, the water sample is mixed with a reagent (such as potassium dichromate solution) and subjected to a high-temperature digestion reaction in a strong sulfuric acid medium and a catalyst (such as silver sulfate). After the reaction is complete, the sample is cooled and measured by spectrophotometry. Spectrophotometry measures light absorption at a specific wavelength (such as 610 nm). At this wavelength, the absorbance of trivalent chromium is directly proportional to the COD value in the sample. By measuring the absorbance of trivalent chromium in the digested sample, its increase is determined. This increase in trivalent chromium absorbance is then converted to the COD value of the sample using a known calibration curve or standard formula.

[0058] The switching of the passage of the rotary cutting valve 3 is controlled by a stepping motor. The internal flow path switching mechanism is a plane shear switching with almost no dead volume. When certain easily crystallized liquids crystallize, it will not affect the flow path switching, thereby improving the stability of the system.

[0059] The pump body 4 can be a peristaltic pump, a plunger pump, a diaphragm pump, or other suitable pump type. Its primary function is to drive the flow of fluid within the hose 5. Fluid can flow bidirectionally within the hose 5: from the carrier liquid storage chamber 11 to the first common port 31, and vice versa. This bidirectional flow design ensures that fluid can flow flexibly within the system as needed, increasing the system's operational flexibility and the accuracy of fluid delivery.

[0060] It should be noted that the "connection between the hose 5 and the pump body 4" refers to the section of the hose 5 installed in the pump body 4. Taking a peristaltic pump as an example, when the peristaltic pump is operating, the roller (or pressure head) of the peristaltic pump squeezes along the length of the hose 5. The point where the hose 5 is squeezed by the peristaltic pump is the "connection between the hose 5 and the pump body 4."

[0061] It can be understood that the micro-flow water quality online monitoring system of the present invention effectively solves the problem of inaccurate capacity caused by air mixing in the prior art by always maintaining the carrier liquid at the connection between the hose 5 and the pump body 4. Specifically, the presence of the carrier liquid ensures that when the pump body 4 is working, the squeezed part of the hose 5 is always filled with liquid. This feature ensures the airtightness inside the hose 5 and prevents air from entering the pipeline. When the pump body 4 drives the fluid, since there is carrier liquid inside the hose 5 squeezed by the pump body 4, air cannot flow into the hose 5 from the port on the hose 5 away from the first common interface 31, and then flow in the direction close to the first common interface 31 inside the hose 5. Therefore, the air volume inside the pipe section of the hose 5 from the pump body 4 to the first common interface 31 is constant and does not change. This design ensures that when extracting water samples or reagents, external air will not enter the pipe section where the water samples and reagents flow, thereby avoiding volume fluctuations and inaccuracies caused by the flow of air. This airtight design ensures that the extraction capacity of water samples and reagents is always stable and accurate, effectively overcoming the capacity error problem caused by air flow in traditional peristaltic pump systems, significantly improving the accuracy of quantitative delivery of water samples and reagents, and ensuring the reliability and accuracy of subsequent test results.

[0062] During the specific implementation process, in some embodiments, the rotary cutting valve 3 also includes a waste selection interface 35. Before extracting water samples or reagents, the rotary cutting valve 3 is switched to the waste selection interface 35, and the pump body 4 is rotated forward to drive the carrier liquid in the carrier liquid storage chamber 11 to flow until it is discharged from the waste selection interface 35. At this time, there is carrier liquid in the hose 5. Then, the rotary cutting valve 3 is switched to the gas selection interface 34, and the pump body 4 is reversed to drive the gas to flow into the hose 5. In this way, there are carrier liquid and gas in the hose 5 at the same time. Afterwards, the rotary cutting valve 3 is switched to the water sample selection interface 32 or the reagent selection interface 36, and a certain volume of water sample or reagent can be extracted by reversing the pump body 4.

[0063] Furthermore, in some embodiments, the fluid storage module 1 is formed with a gas storage chamber 16, which is connected to the gas selection interface 34. In this embodiment, the gas storage chamber 16 is used to store processed clean gas. This clean gas does not contain impurities, particulate matter, microorganisms, or other contaminants. The gas can be high-purity nitrogen, high-purity argon, or high-purity air (clean air obtained by removing particulate matter, moisture, and organic matter from the air through air purification equipment such as filters and adsorption towers). In addition, in this embodiment, the carrier fluid is selected to be high-purity water or an antibacterial solution. Before extracting the water sample or reagent, part of the hose 5 contains the carrier fluid and part of the hose 5 contains the clean gas. In this way, when the water sample or reagent is extracted into the hose 5, the presence of impurities or microorganisms in the hose 5 can be avoided, thereby preventing contamination of the water sample or reagent, thereby ensuring the purity of the reaction process and the accuracy of the results.

[0064] It should also be noted that during the operation of the system, the fluid storage module 1 can form a plurality of waste storage chambers, some of which are used to store waste liquid (such as the solution after the digestion reaction), some of which are used to store waste water (such as the carrier liquid after use), and some of which are used to store used gas. The rotary cutting valve 3 has a plurality of waste selection interfaces 35, and these waste selection interfaces 35 are respectively connected to the waste storage chambers to discharge the waste liquid, waste water or used gas respectively. In this way, the waste is discharged in a classified manner to avoid pollution to the environment.

[0065] Optionally, the hose 5 is made of a transparent material (such as polycarbonate (PC), polypropylene (PP) or borosilicate glass, etc.), and a liquid detection sensor 6 is provided on the portion of the hose 5 located between the pump body 4 and the first common interface 31. The liquid detection sensor 6 is used to detect the presence of liquid in the hose 5, and the liquid presence status includes the presence of liquid and the absence of liquid.

[0066] The liquid detection sensor 6 can be a photoelectric sensor, an ultrasonic sensor, or other suitable detection sensor. Taking a peristaltic pump as an example, when the peristaltic pump is in operation, the angle of its rotation is related to the amount of water sample or reagent flowing into the hose 5. After the peristaltic pump rotates a certain angle, the liquid detection sensor 6 determines whether there is liquid at a preset position of the hose 5, and can determine whether the process of extracting the water sample or reagent is accurate. Assuming that the installation position of the liquid detection sensor 6 represents that the volume of the hose 5 from this position to the first common interface 31 is 0.5ml, the peristaltic pump rotates 90 degrees, which is just enough to drive 0.5ml of water sample or 0.5ml of reagent to flow into the hose 5. At this time, the liquid detection sensor 6 detects whether there is liquid inside the hose 5 at its installation position, and can determine whether the volume of the extracted water sample or reagent is accurate. If the result is that there is no liquid inside the hose 5, it is necessary to re-adjust and optimize the system components or re-extract.

[0067] Optionally, the number of the liquid detection sensors 6 is at least two, and the at least two liquid detection sensors 6 are arranged at intervals.

[0068] At least two liquid detection sensors 6 can be placed at different locations within the hose 5, spaced a certain distance apart. For example, one sensor can be located near the pump body 4, while the other can be located near the first common interface 31. The number and spacing of the sensors can be adjusted based on specific application requirements to ensure comprehensive coverage of the liquid flow status within the hose 5.

[0069] Optionally, the micro-flow water quality online monitoring system includes a first three-way valve 7 , which includes a first selection interface 71 , a second selection interface 72 , and a second common interface 73 ;

[0070] The hose 5 includes a first pipe section 51, a second pipe section 52 and a third pipe section 53. The first pipe section 51 is connected to the first common interface 31 and the second common interface 73 respectively. The pump body 4 is provided on the first pipe section 51.

[0071] The second pipe section 52 is communicated with the first selection interface 71 and the carrier liquid storage chamber 11 respectively, and the third pipe section 53 is communicated with the second selection interface 72 and the gas outside the micro-flow water quality online monitoring system respectively.

[0072] In specific implementation, the first three-way valve 7 can be implemented using a conventional three-way valve structure, such as a three-way electric valve or a three-way solenoid valve, which includes a valve body and a valve core. The rotation or movement of the valve core can selectively connect different interfaces.

[0073] By adding the first three-way valve 7, the system can achieve more flexible and precise fluid path control. For example, when the other end of the third pipe segment 53 is directly connected to the external environment, when it is necessary to discharge the solution after the reaction in the digestion reaction chamber 211, the first three-way valve 7 can be switched to the second selection interface 72, and the pump body 4 is reversed. During this process, the gas in each pipeline can be discharged through the third pipe segment 53. After the solution in the digestion reaction chamber 211 flows into the first pipe segment 51, the rotary cutting valve 3 is switched to the waste selection interface 35, and the first three-way valve 7 can be switched to the first selection interface 71. The pump body 4 rotates forward to discharge the solution in the first pipe segment 51.

[0074] Optionally, a first valve body structure 24 is provided between the first interface 22 and the measurement selection interface 33 , and a second valve body structure 25 is provided at the second interface 23 .

[0075] In a specific implementation, the first valve body structure 24 can be a two-way electric on-off displacement valve or a two-way electromagnetic valve, and the second valve body can also be a two-way electric on-off displacement valve or a two-way electromagnetic valve.

[0076] By adding the first valve body structure 24 and the second valve body structure 25, the system can more flexibly control the flow paths of different fluids between the interfaces, ensuring that the fluids are not disturbed by the outside world during the measurement and reaction process, and maintaining high purity and high precision.

[0077] The rotary cutting valve 3 includes at least one reserved selection interface 37. The reserved selection interface 37 is used for possible future functional expansion, such as adding new reagents or different types of fluids.

[0078] The fluid storage module 1 also includes a span verification fluid storage chamber 14 and a range calibration fluid storage chamber 15. The rotary cut valve 3 includes a function selection interface 38. The micro-flow water quality online monitoring system includes a second three-way valve 8. The second three-way valve 8 includes a third selection interface 81, a fourth selection interface 82 and a third common interface 83. The third selection interface 81 is connected to the span verification fluid storage chamber 14, the fourth selection interface 82 is connected to the range calibration fluid storage chamber 15, and the third common interface 83 is connected to the function selection interface 38.

[0079] The span check solution is used to verify and confirm the accuracy and linearity of the water quality testing system across its entire measurement range. By delivering a known concentration of span check solution into the digestion reaction chamber 211 for testing, the linear relationship between the system output and the known concentration is verified, ensuring that the system's measurement results remain consistent across different concentration ranges.

[0080] By regularly using span verification fluid, the measurement deviation of the system can be discovered, and adjustments and corrections can be made in time to ensure the long-term stability and accuracy of the system.

[0081] Span calibration fluids are used to calibrate and adjust the measurement range of water quality testing systems. By using span calibration fluids of known concentration, the system's detection range can be calibrated to ensure the system can accurately measure sample concentrations within the expected range.

[0082] Optionally, the digestion measurement module 2 includes a digestion tube 21, a measurement transmitter 26 and a measurement receiver 27, and the digestion tube 21 is formed with a digestion reaction chamber 211, a first interface 22 and a second interface 23;

[0083] The measurement transmitter 26 and the measurement receiver 27 are respectively arranged on two opposite sides of the digestion tube 21;

[0084] The measuring transmitter 26 includes a shell 261 and a light-emitting element 262 arranged on the shell 261. The shell 261 is formed with a measuring light channel 261a. The diameter of the measuring light channel 261a is smaller than the inner diameter of the digestion tube 21. The light emitted by the light-emitting element 262 is guided through the measuring light channel 261a to irradiate the digestion tube 21. The measuring receiver 27 is used to receive the light passing through the digestion tube 21.

[0085] In a specific implementation, the digestion tube 21 can be made of a transparent material that is resistant to high temperatures and corrosion, such as glass or quartz, so that light can pass through smoothly. A fine measurement light channel 261a is provided on the housing 261 of the measurement transmitter 26. The diameter of the light channel is smaller than the inner diameter of the digestion tube 21, which can effectively concentrate the light of the light-emitting element 262, so that the light passes through the liquid in the digestion tube 21 with high intensity and accuracy, thereby improving the accuracy of optical measurement. The light-emitting element 262 can be an LED or a laser diode, and the light emitted is irradiated on the liquid in the digestion tube 21 through the light channel. The measurement receiver 27 is arranged on the other side of the digestion tube 21 for receiving the light after passing through the liquid. The measurement receiver 27 can be a photodiode or a photoresistor.

[0086] Optionally, the inner diameter of the digestion tube 21 is greater than or equal to 6 mm and less than or equal to 10 mm;

[0087] The diameter of the measurement light channel 261 a is greater than 0 mm and less than or equal to 0.8 mm.

[0088] The micro-flow water quality online monitoring system of the present application is used to measure water samples with smaller volumes, which can reduce the discharge of waste after the water sample reaction because a digestion tube 21 with a smaller diameter is designed, and its inner diameter can be 6mm, 7mm, 8mm, 9mm or 10mm.

[0089] When the diameter of the digestion tube 21 is small, the curvature of its peripheral wall surface is large. In order to avoid the scattering and absorption of light on the peripheral wall of the digestion tube 21, the dimensions of the digestion tube 21 and the light channel are precisely controlled to avoid unnecessary measurement errors and improve the consistency and reliability of the detection results.

[0090] In a specific implementation, the diameter of the measuring light channel 261 a can be 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm or 0.8 mm.

[0091] Specifically, the measurement transmitter 26 is provided with a reference receiver 28, which may be a photodiode or photoresistor. A lens 263 is provided on the housing 261. Light from the light-emitting element 262 passes through the lens 263, with some of the light being refracted onto the reference receiver 28 by the lens 263. Some of the light passes through the lens 263 and illuminates the digestion tube 21 through the measurement light channel 261a. Alternatively, some of the light is refracted into the measurement light channel 261a by the lens 263, while some of the light passes through the lens 263 and illuminates the reference receiver 28. During subsequent measurements, the absorbance of the water sample can be measured by comparing the results from the reference receiver 28 with the measurement receiver 27. The data comparison process is a widely used technique and will not be described in detail here.

[0092] The present invention also proposes a method for online monitoring of water quality at a small flow rate, which is applied to the above-mentioned online monitoring system for water quality at a small flow rate. Figure 4 As shown, the method for online monitoring of water quality with a small flow rate includes:

[0093] S100, switching the rotary cutting valve to the waste selection interface, driving the carrier liquid in the carrier liquid storage chamber to flow to the waste selection interface through the pump body;

[0094] Specifically, this step causes part of the carrier fluid to be discharged into the waste storage chamber connected to the waste selection interface. This process drives the carrier fluid to flow through the forward rotation of the pump body.

[0095] S200, switching the rotary cutting valve to the gas selection interface, driving the gas outside the rotary cutting valve to flow into the hose through the pump body, so that the hose contains carrier liquid and gas; wherein the connection between the pump body and the hose contains carrier liquid;

[0096] This step drives the gas flow by reversing the pump body. After this step, both carrier fluid and gas exist in the hose.

[0097] S300, switching the rotary cutting valve to the water sample selection interface, driving the water sample in the water sample storage chamber to flow into the hose through the pump body, and during the flow of the water sample, the connection between the pump body and the hose always has carrier liquid;

[0098] This step causes a preset volume of water sample to flow into the hose.

[0099] S400, switching the rotary cutting valve to the reagent selection interface, driving the reagent in the reagent storage chamber to flow into the hose through the pump body, and during the reagent flow process, the connection between the pump body and the hose always has carrier liquid;

[0100] This step drives the preset volume of reagent to flow into the hose. When there are multiple reagents, you can switch to different reagent selection interfaces so that different reagents can enter the hose in sequence.

[0101] S500, switching the rotary cutting valve to the measurement selection interface, and driving the water sample and reagent in the hose to flow into the digestion reaction chamber through the pump body.

[0102] Furthermore, the rotary cutting valve is switched to the gas selection interface, and the gas outside the rotary cutting valve is driven to flow into the hose through the pump body, including:

[0103] Connecting the gas selection interface to the gas storage chamber to heat the gas in the gas storage chamber to a first preset temperature;

[0104] The rotary cutting valve is switched to the gas selection interface, and the heated gas in the gas storage chamber is driven to flow into the hose through the pump body, and the heated gas is allowed to stay in the hose for a first preset time.

[0105] In this step, by heating the gas, on the one hand, the gas can be disinfected to prevent microorganisms from contaminating water samples and reagents, and the heated gas is allowed to stay in the hose for a certain period of time to ensure that the inner wall of the hose is fully dried to prevent residual moisture from affecting the concentration of subsequent water samples.

[0106] In this step, the first preset duration is calculated by the following formula:

[0107] ;

[0108] in, is the first preset duration, is the convective heat transfer coefficient, is the surface area of ​​the gas region in the hose, is the initial temperature of the gas when it enters the hose, is the ambient temperature, The temperature difference required for drying.

[0109] Specifically, It can be obtained through experiments or by consulting relevant literature. The convective heat transfer coefficient depends on factors such as gas type, flow state, and pipe material. Based on the size of the hose and the length covered by the hot gas, calculate the surface area actually involved in heat exchange. The temperature of the environment where the pipeline is located is measured by a temperature sensor, taking into account changes in different seasons and climatic conditions. According to experience or experimental data, set the temperature difference required to achieve effective drying effect.

[0110] This formula calculates the residence time of clean gas within the pipeline by taking into account the initial temperature of the hot gas, the ambient temperature, and the heat transfer efficiency, ensuring that the gas remains within the pipeline long enough to effectively dry out the moisture on the inner wall of the pipeline. By accurately calculating the first preset duration, the inner wall of the pipeline is fully dried before each test, preventing residual moisture from interfering with the water sample test, thereby improving the accuracy and reliability of the test results.

[0111] For example, assume the following conditions:

[0112] Convective heat transfer coefficient =10W / m²·K, the surface area of ​​the hot gas area in the hose =0.5m², initial hot gas temperature =80°C. Winter ambient temperature , summer ambient temperature The temperature difference required for drying =20°C.

[0113] Calculating winter heat loss :

[0114] .

[0115] Calculate the duration of the first winter preset :

[0116] =400 / 20=20s.

[0117] Calculating winter heat loss :

[0118] .

[0119] Calculate the duration of the first winter preset :

[0120] =250 / 20=12.5s.

[0121] This example shows that in winter, due to the lower ambient temperature, the hot gas cools down faster, so a longer preset time (20 seconds) is required to ensure that the moisture on the inner wall of the pipe is fully dried. In contrast, in summer, due to the higher ambient temperature, the hot gas cools down more slowly, so the required preset time is shorter (12.5 seconds). This calculation method ensures that the system can achieve effective drying effects under different environmental conditions, thereby improving the accuracy and reliability of online water quality monitoring.

[0122] It should be noted that when removing the influence of residual moisture on the pipe wall on the water quality detection structure, in addition to using hot gas to dry the moisture, the following steps can be used to further eliminate the influence:

[0123] After drying with hot gas, the rotary valve is switched to the water sample selection port. The pump (reverse rotation) drives a portion of the water sample into the hose for rinsing. The rotary valve is then switched to the waste selection port. The pump (forward rotation) drives the rinsed water sample to be discharged into the waste storage chamber, while the carrier liquid does not enter the waste storage chamber. Specifically, during the process of discharging the rinsed water sample, the carrier liquid is prevented from flowing to the location on the first pipeline where the water sample is measured (the location of the two liquid detection sensors). This prevents the carrier liquid from remaining in this location and affecting subsequent testing.

[0124] By rinsing with water samples, only water samples can remain on the tube wall. At the same time, the rinsing process can also remove solid impurities in the drying process.

[0125] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made by using the contents of the present invention description and drawings under the inventive concept of the present invention, or direct / indirect application in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for online monitoring of water quality at a low flow rate, applied to an online monitoring system for water quality at a low flow rate, characterized in that: The micro-flow water quality online monitoring system comprises: A fluid storage module (1) is formed with a carrier liquid storage chamber (11), a water sample storage chamber (12), and at least one reagent storage chamber (13); A digestion measurement module (2) is formed with a digestion reaction chamber (211), a first interface (22) and a second interface (23), wherein the digestion reaction chamber (211) is communicated with the first interface (22) and the second interface (23) respectively; The rotary cutting valve (3) comprises a first common interface (31), a water sample selection interface (32), a measurement selection interface (33), a gas selection interface (34), a waste selection interface (35) and at least one reagent selection interface (36), wherein the first common interface (31) is connected to the carrier liquid storage chamber (11) through a hose (5), the water sample selection interface (32) is connected to the water sample storage chamber (12), the measurement selection interface (33) is connected to the first interface (22), the at least one reagent selection interface (36) corresponds to the at least one reagent storage chamber (13), and the reagent selection interface (36) is connected to the corresponding reagent storage chamber (13); A pump body (4) is provided on the hose (5), and the pump body (4) is used to drive the fluid in the hose (5) to flow from the first common interface (31) to the direction close to the carrier liquid storage chamber (11), so as to extract the water sample in the water sample storage chamber (12), the reagent in the reagent storage chamber (13), or the gas at the gas selection interface (34) into the hose (5). The pump body (4) is also used to drive the fluid in the hose (5) to flow from the carrier liquid storage chamber (11) to the direction close to the first common interface (31), so as to extract the carrier liquid in the carrier liquid storage chamber (11) into the hose (5); wherein, During the process of drawing the water sample or reagent into the hose (5), the connection between the hose (5) and the pump body (4) always has carrier fluid; The method for online monitoring of water quality with a small flow rate comprises: Switch the rotary cutting valve to the waste selection interface, and drive the carrier liquid in the carrier liquid storage chamber to flow to the waste selection interface through the pump body; Switching the rotary cutting valve to the gas selection interface, driving the gas outside the rotary cutting valve to flow into the hose through the pump body, so that the hose contains carrier liquid and gas; wherein the connection between the pump body and the hose contains carrier liquid; wherein, switching the rotary cutting valve to the gas selection interface, driving the gas outside the rotary cutting valve to flow into the hose through the pump body, comprises: connecting the gas selection interface with a gas storage chamber, heating the gas in the gas storage chamber to a first preset temperature; switching the rotary cutting valve to the gas selection interface, driving the heated gas in the gas storage chamber to flow into the hose through the pump body, and allowing the heated gas to stay in the hose for a first preset time; The first preset duration is calculated by the following formula, specifically: ； in, is the first preset duration, is the convective heat transfer coefficient, is the surface area of ​​the gas region in the hose, is the initial temperature of the gas when it enters the hose, is the ambient temperature, The temperature difference required to dry the carrier fluid on the hose wall; Switch the rotary cutting valve to the water sample selection interface, and drive the water sample in the water sample storage chamber to flow into the hose through the pump body. During the flow of the water sample, the connection between the pump body and the hose always has carrier liquid; Switch the rotary cutting valve to the reagent selection interface, and drive the reagent in the reagent storage chamber to flow into the hose through the pump body. During the flow of the reagent, the connection between the pump body and the hose always has carrier liquid; The rotary cutting valve is switched to the measurement selection interface, and the water sample and reagent in the hose are driven to flow into the digestion reaction chamber through the pump body.

2. The method for online monitoring of water quality at a low flow rate according to claim 1, wherein: The hose (5) is made of a transparent material. A liquid detection sensor (6) is provided on the portion of the hose (5) located between the pump body (4) and the first common interface (31). The liquid detection sensor (6) is used to detect the presence of liquid in the hose (5), wherein the presence of liquid includes the presence of liquid and the absence of liquid.

3. The method for online monitoring of water quality at a low flow rate according to claim 2, wherein: The number of the liquid detection sensors (6) is at least two, and the at least two liquid detection sensors (6) are arranged at intervals.

4. The method for online monitoring of water quality at a low flow rate according to claim 1, wherein: The micro-flow water quality online monitoring system comprises a first three-way valve (7), wherein the first three-way valve (7) comprises a first selection interface (71), a second selection interface (72) and a second common interface (73); The hose (5) comprises a first pipe section (51), a second pipe section (52) and a third pipe section (53); the first pipe section (51) is connected to the first common interface (31) and the second common interface (73) respectively; and the pump body (4) is arranged on the first pipe section (51); The second pipe section (52) is respectively connected to the first selection interface (71) and the carrier liquid storage chamber (11), and the third pipe section (53) is respectively connected to the second selection interface (72) and the gas outside the micro-flow water quality online monitoring system.

5. The method for online monitoring of water quality at a low flow rate according to claim 1, wherein: A first valve body structure (24) is provided between the first interface (22) and the measurement selection interface (33), and a second valve body structure (25) is provided at the second interface (23); and / or, The rotary cutting valve (3) includes at least one reserved selection interface (37); and / or, The fluid storage module (1) further comprises a span verification fluid storage chamber (14) and a range calibration fluid storage chamber (15); the rotary cut valve (3) comprises a function selection interface (38); the micro-flow water quality online monitoring system comprises a second three-way valve (8); the second three-way valve (8) comprises a third selection interface (81), a fourth selection interface (82) and a third common interface (83); the third selection interface (81) is in communication with the span verification fluid storage chamber (14); the fourth selection interface (82) is in communication with the range calibration fluid storage chamber (15); and the third common interface (83) is in communication with the function selection interface (38).

6. The method for online monitoring of water quality at a low flow rate according to claim 1, wherein: The digestion measurement module (2) comprises a digestion tube (21), a measurement transmitter (26) and a measurement receiver (27); the digestion tube (21) is formed with the digestion reaction chamber (211), the first interface (22) and the second interface (23); The measurement transmitter (26) and the measurement receiver (27) are respectively arranged on two opposite sides of the digestion tube (21); The measuring emitting element (26) comprises a housing (261) and a light emitting element (262) provided on the housing (261); the housing (261) is formed with a measuring light channel (261a); the diameter of the measuring light channel (261a) is smaller than the inner diameter of the digestion tube (21); the light emitted by the light emitting element (262) is guided through the measuring light channel (261a) to irradiate the digestion tube (21); and the measuring receiving element (27) is used to receive the light that passes through the digestion tube (21).

7. The method for online monitoring of water quality at a low flow rate according to claim 6, wherein: The inner diameter of the digestion tube (21) is greater than or equal to 6 mm and less than or equal to 10 mm; The diameter of the measuring light channel (261a) is greater than 0 mm and less than or equal to 0.8 mm.

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