Automatic water quality analysis and liquid feeding device and method

Abstract

The invention discloses a water quality automatic analysis liquid inlet device and method, and relates to the technical field of water quality automatic analysis instruments, and the liquid inlet device comprises a liquid path module which is provided with at least two liquid storage bins; the air path module is used for providing controllable negative pressure and comprises a vacuum air pump and a pressure control unit; interfaces of the liquid path valve are respectively communicated with the at least two liquid storage bins and the reagent flow path, and the liquid path valve is used for switching the liquid inlet flow path; a connector of the gas path valve communicates with the at least two liquid storage bins and the gas path module, and the gas path valve is used for switching a gas suction flow path; the integrated control module is electrically connected with the gas path module, the liquid path valve and the gas path valve; wherein the integrated control module is configured to control the liquid path valve and the gas path valve to be synchronously switched, so that the at least two liquid storage bins alternately execute liquid inlet operation and waste discharge operation; wherein the liquid inlet operation is specifically as follows: negative pressure is applied to the liquid storage bin for current liquid inlet through the gas circuit module, so that to-be-analyzed liquid or a reagent is continuously sucked in through the liquid inlet interface.

Description

Technical Field

[0001] This application relates to the field of automatic water quality analysis instruments, and more specifically, to a device and method for online water quality monitoring or laboratory analysis that enables continuous and stable liquid intake. Background Technology

[0002] Currently, common water pollution indicators include total phosphorus, total nitrogen, ammonia nitrogen, and permanganate index. The testing process involves multiple steps such as sample injection, sample digestion, reagent addition, sample mixing, data acquisition and analysis. Traditional detection methods rely on manual operation, which is cumbersome and time-consuming.

[0003] With the development of technology, rapid testing instruments, semi-automatic instruments, and automatic instruments have emerged in the market. Rapid testing instruments typically use electrode methods and rapid display test strips for determination, which can quickly test samples, but the test results have large errors for complex water samples; semi-automatic instruments require manual addition of reagents and samples, manual data collection, and manual processing of test results, and the whole process is time-consuming and labor-intensive.

[0004] Automated instruments enable automatic sample introduction, digestion, reagent introduction, and test result calculation, which improves detection efficiency to a certain extent. However, automated instruments typically use peristaltic pumps, stopper pumps, or syringe pumps for liquid introduction. Peristaltic pumps achieve liquid flow by squeezing the pump tube with rollers. However, after prolonged squeezing, the pump tube diameter deforms and the material ages, leading to changes in reagent flow rate and changes in the acquired signal. This makes it impossible to guarantee stable testing of samples over a long period of time.

[0005] Injection pumps or plunger pumps rely on the reciprocating motion of the plunger in the cylinder to change the volume of the sealed working chamber to achieve liquid injection. During liquid injection, the reagent is first drawn in and then discharged to complete one liquid injection process. Due to its inherent "draw-discharge" intermittent working mode, it cannot achieve true continuous liquid injection, which restricts the efficiency of batch sample testing. Summary of the Invention

[0006] This invention aims to solve the above-mentioned problems by providing an automatic water quality analysis liquid feeding device and method. Its core lies in eliminating easily damaged mechanical pumping components and achieving uninterrupted liquid feeding without fluctuations through a system design based on the principle of negative pressure and alternating operation of two chambers.

[0007] In a first aspect, embodiments of this application provide an automatic water quality analysis liquid inlet device, the liquid inlet device comprising:

[0008] The liquid circuit module is provided with at least two liquid storage tanks, each of which is provided with a liquid inlet, a liquid outlet and an air extraction port;

[0009] The air circuit module, used to provide controllable negative pressure, includes a vacuum pump and a pressure control unit;

[0010] A liquid flow valve, the interface of which is connected to at least two of the liquid storage tanks and reagent flow paths respectively, is used to switch the liquid inlet flow path;

[0011] A pneumatic valve, whose interface is connected to at least two of the liquid storage tanks and the pneumatic module respectively, is used to switch the pumping flow path;

[0012] An integrated control module is electrically connected to the gas circuit module, the liquid circuit valve, and the gas circuit valve, and is used to control the output power of the gas circuit module and the switching of the liquid circuit valve and the gas circuit valve according to the pressure feedback signal in the liquid storage tank;

[0013] A waste liquid treatment module is connected to the liquid outlet interface for discharging waste liquid;

[0014] The integrated control module is configured to control the synchronous switching of the liquid valve and the gas valve, so that at least two of the liquid storage tanks alternately perform liquid inlet operation and waste discharge operation;

[0015] Specifically, the liquid inlet operation involves applying negative pressure to the liquid storage chamber through the gas path module, so that the liquid to be analyzed or the reagent is continuously drawn in through the liquid inlet interface.

[0016] Preferably, the integrated control module adjusts the power of the vacuum pump in real time through the pressure control unit to maintain the pressure stability in the liquid storage tank currently receiving liquid, thereby ensuring a constant liquid inflow rate.

[0017] Preferably, the operating parameters of the liquid inlet device meet the following conditions: the negative pressure ΔP generated by the gas circuit module in the liquid storage tank is sufficient to overcome the total fluid resistance of the liquid inlet pipeline from the liquid inlet to the liquid storage tank.

[0018] Preferably, the negative pressure ΔP is calculated and set based on the friction factor, pipe length, pipe diameter, fluid density, and flow velocity.

[0019] Specifically, the formula for calculating negative pressure ΔP can be estimated and set as follows: ΔP=f·(L / d)·(ρv² / 2), where f is the friction factor, L is the pipe length, d is the pipe diameter, ρ is the fluid density, and v is the flow velocity.

[0020] Preferably, the integrated control module is also used to monitor the liquid level of the storage tank, and control the switch to another storage tank when the liquid level of one storage tank reaches a preset threshold.

[0021] Preferably, the preset threshold is set based on the effective volume of the liquid storage tank.

[0022] Specifically, the preset threshold is 70% to 80% of the effective volume of the liquid storage tank.

[0023] Preferably, the liquid circuit valve and the gas circuit valve are composed of a single valve body or a combination of multiple valve bodies.

[0024] Secondly, this application also provides an automatic water quality analysis liquid feeding method, applicable to the liquid feeding device in the first aspect, the liquid feeding method comprising the following steps:

[0025] In the liquid inlet step, the control liquid circuit valve and the air circuit valve connect the liquid inlet flow path and the air extraction flow path to the first liquid storage tank, and the air circuit module is activated to apply negative pressure, so that the liquid is continuously drawn into the first liquid storage tank;

[0026] In the switching step, when the switching conditions are met, the liquid circuit valve and the gas circuit valve are controlled to switch synchronously, switching the liquid inlet flow path and the gas extraction flow path to the second liquid storage tank, and the liquid is continuously drawn into the second liquid storage tank.

[0027] In the waste discharge step, the waste liquid treatment module is activated to discharge the waste liquid from the storage tank that has already been filled with liquid.

[0028] Preferably, the switching condition is that the liquid level in the first storage tank reaches a preset threshold, or the liquid inlet time reaches a preset duration.

[0029] Preferably, during the liquid inlet step, the pressure in the liquid storage tank being inlet is monitored in real time, and the negative pressure output of the gas path module is dynamically adjusted to stabilize the liquid inlet flow rate.

[0030] The beneficial effects of this invention are as follows:

[0031] This invention relates to an automatic water quality analysis liquid feeding device and method. By adopting a systematic design of "negative pressure drive, dual-compartment alternation, and closed-loop control", it overcomes the inherent defects of traditional liquid feeding technology. Through an innovative technical approach, it simultaneously overcomes the two core problems of "poor continuity" and "low stability" in traditional water quality analysis liquid feeding devices.

[0032] This invention, by setting up dual liquid storage chambers and coordinating the synchronous switching of liquid and gas valves, allows one chamber to receive liquid while the other can discharge waste or standby. Compared to the intermittent operation mode of traditional syringe pumps, it enables seamless continuous liquid feeding with longer standby times, completely eliminating the "window period" in the liquid feeding process. It is particularly suitable for applications requiring long-term online monitoring or continuous analysis of large batches of samples, significantly improving the overall detection efficiency of the instrument.

[0033] This invention eliminates all mechanical moving parts that directly act on the fluid, employing a negative pressure suction principle based on precise pneumatic pressure control to drive the fluid. Theoretical calculations and practical applications show that the negative pressure required to maintain a stable flow rate within the chamber is extremely small (e.g., only about 212 Pa pressure difference), and this driving pressure difference can be easily maintained at a constant set value through real-time monitoring and closed-loop feedback adjustment of the integrated control module. This fundamentally eliminates the root cause of flow rate attenuation due to mechanical wear and fatigue, achieving long-term flow rate stability close to the theoretical limit, and providing a fundamental guarantee for obtaining highly repeatable and reliable detection data.

[0034] The integrated control module of this invention not only manages the coordinated switching of valves but also adjusts the vacuum pump power in real time based on pressure sensor feedback, forming an intelligent closed-loop control system. This adaptive adjustment capability enables the system to automatically compensate for interference caused by rising liquid levels, minor changes in pipeline characteristics, or environmental fluctuations, further enhancing robustness. Simultaneously, because the core power unit (gas circuit module) does not directly contact corrosive reagents or complex samples, and because it avoids the need for periodically replaced consumables such as peristaltic pump tubing and syringe pistons, it reduces potential failure points, lowers the frequency and cost of long-term maintenance, and improves the overall reliability of the equipment. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a schematic diagram of the structure of an automatic water quality analysis liquid inlet device provided in an embodiment of this application;

[0037] Figure 2 This is a schematic diagram of the equivalent fluid passing through a straight circular pipe.

[0038] In the diagram: 1. Liquid circuit module; 2. Liquid circuit valve; 3. Gas circuit valve; 4. Gas circuit module; 5. Integrated control module; 6. Waste liquid treatment module; 11. Air extraction interface; 12. Liquid inlet interface; 13. Liquid outlet interface. Detailed Implementation

[0039] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings.

[0040] In the following description, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The following description provides multiple embodiments of this application, which can be substituted or combined with each other. Therefore, this application can also be considered to include all possible combinations of the same and / or different embodiments described. Thus, if one embodiment includes features A, B, and C, and another embodiment includes features B and D, then this application should also be considered to include embodiments containing one or more other possible combinations of A, B, C, and D, even if such embodiments are not explicitly described in the following text.

[0041] The following description provides examples and does not limit the scope, applicability, or examples set forth in the claims. Changes may be made to the function and arrangement of the described elements without departing from the scope of this application. Various processes or components may be appropriately omitted, substituted, or added to the examples. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Furthermore, features described with respect to some examples may be combined into other examples.

[0042] According to the first aspect of this application, see Figure 1 , Figure 1 This is a schematic diagram of an automatic water quality analysis inlet device provided in an embodiment of this application. In this embodiment, the inlet device includes:

[0043] The liquid circuit module 1 is provided with at least two liquid storage tanks, each of which is provided with a liquid inlet 12, a liquid outlet 13 and an air extraction port 11;

[0044] Air circuit module 4, used to provide controllable negative pressure, includes a vacuum pump and a pressure control unit;

[0045] Liquid valve 2, whose interface is connected to at least two liquid storage tanks and reagent flow path respectively, is used to switch the liquid inlet flow path;

[0046] The gas valve 3 has an interface that is connected to at least two liquid storage tanks and the gas module 4, respectively, and is used to switch the pumping gas path.

[0047] The integrated control module 5 is electrically connected to the gas circuit module 4, the liquid circuit valve 2 and the gas circuit valve 3. It is used to control the output power of the gas circuit module 4 and the switching of the liquid circuit valve 2 and the gas circuit valve 3 according to the pressure feedback signal in the liquid storage tank.

[0048] Waste liquid treatment module 6 is connected to liquid outlet interface 13 and is used to discharge waste liquid;

[0049] Among them, the integrated control module 5 is configured to control the synchronous switching of the liquid valve 2 and the gas valve 3, so that at least two liquid storage tanks alternately perform liquid inlet operation and waste discharge operation;

[0050] Specifically, the liquid inlet operation involves applying negative pressure to the liquid storage chamber of the current liquid inlet through the gas path module 4, so that the liquid to be analyzed or the reagent is continuously drawn in through the liquid inlet interface 12.

[0051] In this application, the integrated control module 5 adjusts the power of the vacuum pump in real time through the pressure control unit to maintain the pressure stability in the liquid storage tank where the liquid is currently being introduced, thereby ensuring a constant liquid flow rate.

[0052] Specifically, the liquid path module 1 has at least two independent liquid storage chambers, such as chamber A and chamber B. Each liquid storage chamber is equipped with an inlet port 12, an outlet port 13, and a suction port 11, thus forming independent liquid and gas passages. The gas path module 4 is the power source of the entire device, which includes a vacuum pump and a pressure control unit, used to generate and precisely control the negative pressure acting on the liquid storage chambers. The valve system includes a liquid path valve 2 and a gas path valve 3, both preferably three-way two-position valves. The three ports of the liquid path valve 2 are respectively connected to liquid storage chamber A, an external reagent or sample flow path, and liquid storage chamber B, used to switch the liquid inflow path. The three ports of the gas path valve 3 are respectively connected to liquid storage chamber A, the gas path module, and liquid storage chamber B, used to switch the object to which the negative pressure is applied.

[0053] The integrated control module 5 is connected to the pneumatic module, liquid valve, and pneumatic valve signal control, and is responsible for coordinating all actions; it receives feedback signals from the pressure sensor in real time (monitoring the pressure inside the storage tank) and dynamically adjusts the output power of the vacuum pump in the pneumatic module accordingly. The waste liquid treatment module is connected to the outlet port of the storage tank for periodically or as needed to empty the tank containing collected waste liquid.

[0054] In this application, the integrated control module 5 is programmed to control the synchronous switching of the liquid circuit valve and the gas circuit valve. When it is necessary to switch working chambers, the control module will issue a command to make the liquid circuit valve and the gas circuit valve operate simultaneously, thereby switching the liquid inlet flow path and the gas extraction flow path from the currently working storage chamber (e.g., chamber A) to the preparatory storage chamber (e.g., chamber B). This synchronous switching mechanism is the key to ensuring that the liquid inlet process is completely continuous and uninterrupted.

[0055] The specific implementation method of liquid inlet can be described as follows: when the gas path module applies negative pressure to a liquid storage tank, a pressure difference is formed between the inside of the tank and the outside atmosphere. Driven by this pressure difference, the liquid or reagent to be analyzed is smoothly and continuously drawn into the liquid storage tank through the liquid inlet interface, completely avoiding the pulse delivery of the syringe pump.

[0056] To ensure the stability of the inlet flow rate, the integrated control module 5 implements closed-loop control through the pressure control unit. It monitors the current pressure value in the inlet storage chamber in real time and compares it with the preset target pressure. Once a pressure fluctuation is detected (possibly caused by a rise in liquid level or slight changes in the pipeline), the control module immediately adjusts the power of the vacuum pump to quickly return the pressure in the chamber to the set value, thus fundamentally ensuring a constant inlet flow rate.

[0057] To quantify this control objective, the operating parameters of the device must satisfy the basic principles of fluid dynamics: that is, the negative pressure value ΔP generated by the gas path module must be sufficient to overcome the fluid resistance (i.e., pressure drop along the flow path) generated throughout the entire inlet pipeline from the inlet to the storage tank.

[0058] That is, the operating parameters of the liquid inlet device meet the following conditions: the negative pressure ΔP generated by the gas circuit module 4 in the liquid storage tank is sufficient to overcome the total fluid resistance of the liquid inlet pipeline from the liquid inlet to the liquid storage tank.

[0059] Taking a classic circular pipe as an example, the negative pressure ΔP is calculated and set based on the friction factor, pipe length, pipe diameter, fluid density, and flow velocity.

[0060] Specifically, the formula for calculating negative pressure ΔP is: ΔP=f·(L / d)·(ρv² / 2). This formula is used to estimate and set negative pressure ΔP, where f is the friction factor, L is the pipe length, d is the pipe diameter, ρ is the fluid density, and v is the flow velocity.

[0061] It is understandable that when the shape of the pipe changes, the calculation method of the negative pressure ΔP should be adjusted accordingly in order to obtain a more accurate pressure drop through calculation in order to implement the technical solution of this application.

[0062] In the embodiments of this application, the integrated control module 5 is also used to monitor the liquid level of the storage tank, and control the switch to another storage tank when the liquid level of one storage tank reaches a preset threshold.

[0063] Specifically, based on automatic control logic, the integrated control module 5 can also integrate liquid level monitoring function (such as through liquid level sensor or calculation based on time and flow). When the liquid level of the liquid storage tank that is currently being filled reaches the preset threshold, the control module will automatically trigger the switching program, start the synchronous action of the liquid circuit valve and the gas circuit valve, and transfer the liquid filling task to another empty or emptied liquid storage tank.

[0064] The preset threshold is set based on the effective volume of the liquid storage tank. For example, the preset threshold can be 70% to 80% of the effective volume of the liquid storage tank. Each liquid storage tank has an independent preset threshold set according to its effective volume to determine whether to switch.

[0065] In a preferred embodiment, the preset threshold is set to 70%-80% of the effective volume of the storage tank. For example, for a storage tank with an effective volume of 4 liters, the preset switching level can be set to 3 liters (i.e., 75%). This not only makes full use of the storage space but also provides a buffer time for waste discharge operations, avoiding the risk of overflow due to untimely switching. Based on this design, at a typical influent flow rate (e.g., 5 mL / min), a single tank can operate continuously for more than 10 hours, fully meeting the needs of long-term continuous operation of water quality analysis.

[0066] In practical applications, the liquid circuit module 1 may contain multiple liquid storage tanks, rather than the classic example of two liquid storage tanks described in this application. In this classic configuration, both the liquid circuit valve 2 and the gas circuit valve 3 can be a single valve body, such as a three-way two-position valve, which can meet the usage requirements and realize the function of liquid circuit switching. When there are more liquid storage tanks, the required number of reagent flow paths may increase, and the required interfaces of the corresponding liquid circuit valve 2 and gas circuit valve 3 will increase. In this case, the liquid circuit valve 2 and gas circuit valve 3 can be composed of multiple valve bodies to meet the switching requirements.

[0067] The specific connection method for the combination of multiple valve bodies to form a liquid circuit valve 2 or a gas circuit valve 3 can be implemented based on the understanding and teaching of those skilled in the art regarding the technical solution of this application.

[0068] According to the second aspect of this application, an automatic water quality analysis liquid feeding method is also proposed, wherein the liquid feeding device of the first aspect is used for continuous liquid feeding, and the liquid feeding method includes the following steps:

[0069] In the liquid inlet step, control the liquid circuit valve 2 and the gas circuit valve 3 to connect the liquid inlet flow path and the gas extraction flow path to the first liquid storage tank, and start the gas circuit module 4 to apply negative pressure to continuously draw the liquid into the first liquid storage tank.

[0070] In the switching process, when the switching conditions are met, the control liquid valve 2 and the air valve 3 are switched synchronously to switch the liquid inlet flow path and the air extraction flow path to the second liquid storage tank, and the liquid is continuously drawn into the second liquid storage tank.

[0071] In the waste discharge step, the waste liquid treatment module 6 is activated to discharge the waste liquid from the storage tank that has already been filled with liquid.

[0072] The switching condition is that the liquid level in the first storage tank reaches a preset threshold, or the liquid inlet time reaches a preset duration.

[0073] During the liquid inlet process, the pressure in the liquid storage tank is monitored in real time, and the negative pressure output of the gas path module 4 is dynamically adjusted to stabilize the liquid inlet flow rate.

[0074] In practice, the liquid inlet step is executed first. The control valve directs the flow path to the first liquid storage tank (e.g., tank A) and the gas path module is activated to apply negative pressure, starting continuous liquid inlet. Second, when the switching conditions are met (e.g., the liquid level in the first liquid storage tank reaches a preset threshold or the liquid inlet time reaches a preset duration), the switching step is executed. The valve is operated synchronously to switch the liquid inlet flow path and the negative pressure source to the second liquid storage tank (e.g., tank B), thus relaying the liquid inlet task. Finally, the waste discharge step is executed. The waste liquid treatment module is activated to discharge the waste liquid from the first liquid storage tank that has completed the liquid inlet task.

[0075] Throughout this process, the liquid inlet step always includes a pressure closed-loop control sub-step, which involves real-time monitoring of the working chamber pressure and dynamic adjustment of the negative pressure output to ensure the stability of the liquid inlet flow rate.

[0076] The overall technical solution of this invention stems from a deep understanding of the bottlenecks in existing technologies. The flow rate attenuation of traditional peristaltic pumps and the intermittent liquid inlet of syringe pumps are two major problems hindering the efficient, stable, and continuous operation of water quality analyzers. Therefore, this invention proposes a fundamental solution: replacing mechanical pumping with negative pressure suction and designing a dual-storage-tank alternating working mechanism. The core idea is to provide a stable negative pressure to the storage tanks through a precisely controlled pneumatic system, using this as the driving force for liquid flow; simultaneously, a valve assembly intelligently switches the liquid and pneumatic paths between the two storage tanks, allowing one tank to receive liquid while the other can discharge waste or standby, thus achieving seamless continuous liquid inlet at the system level.

[0077] refer to Figure 1 In a specific example, the liquid circuit module 1 is connected to the reagent and sample inlet lines and has a dedicated storage tank for storing waste liquid during the testing process. The storage tank is divided into tank A and tank B, each with an external air extraction port 11, a liquid inlet port 12, and a liquid outlet port 13. The liquid circuit valve 2 is a three-way two-position liquid circuit valve with three ports: a, b, and c. Port a connects to storage tank A, port b connects to the reagent flow path, and port c connects to storage tank B. The gas circuit valve 3 is a three-way two-position gas circuit valve with ports d, e, and c. The three interfaces are: port d, port e, and port f, which are connected to the liquid storage compartment A; port d, port e, and port f, which are connected to the gas path module; and port f, which is connected to the liquid storage compartment B. The gas path module 4 is equipped with a vacuum pump and a pressure control unit. The vacuum pump is used to extract gas from the liquid storage compartment, and the pressure control unit is used to stabilize the gas flow rate output by the vacuum pump. The integrated control module 5 monitors the pressure in the liquid storage compartment in real time. The waste liquid treatment module 6 is connected to the liquid outlet interface 13 and is equipped with a waste liquid collection bottle and a waste discharge pump. The waste discharge pump draws the waste liquid in the liquid storage compartment into the waste liquid collection bottle.

[0078] The specific workflow can be summarized as follows:

[0079] In the initial or default state, liquid valve 2 connects ports a and b, and gas valve 3 connects ports d and e. At this time, the liquid storage chamber A is connected to the liquid inlet flow path and the gas path module 4. After startup, the integrated control module 5 instructs the gas path module 4 to operate. The vacuum pump draws gas from chamber A through the suction port 11, creating a stable negative pressure inside. Under atmospheric pressure, the liquid to be analyzed is continuously drawn into chamber A through the liquid inlet port 12. The integrated control module 5 monitors the pressure inside chamber A in real time through a pressure sensor and dynamically adjusts the vacuum pump power through the pressure control unit to maintain the pressure at the set value, thereby ensuring a constant liquid inlet flow rate.

[0080] This process will continue until the liquid level in compartment A reaches a preset height (e.g., 75% of its volume). At this point, the integrated control module 5 issues a switching command, and the liquid valve 2 activates, switching the connection from "ab" to "cb"; simultaneously, the gas valve 3 activates, switching the connection from "de" to "fe". This synchronized switching operation causes the liquid inlet path and negative pressure source to instantly transfer from compartment A to compartment B, and the liquid begins to be drawn into compartment B, while compartment A enters a state awaiting waste discharge.

[0081] During the waste discharge phase, waste liquid treatment module 6 is activated, and the waste discharge pump completely pumps the waste liquid accumulated in compartment A into the waste liquid collection bottle through outlet interface 13. When the liquid level in compartment B reaches the threshold again, the valve switches back to compartment A, and this cycle repeats.

[0082] Because the switching process is rapid, and the supply of liquid inlet power (negative pressure) is only transferred from one compartment to another without interruption, the liquid inlet of the entire system can be considered to be truly objectively continuous.

[0083] In this application, to ensure liquid inlet, the pressure difference between the storage tank and atmospheric pressure must be sufficient to overcome the fluid resistance of the inlet pipe, i.e., the pressure drop ΔP. This problem can be equivalent to the frictional pressure drop along the pipe, a common phenomenon in fluid mechanics, such as... Figure 2 As shown, the process of calculating the compression ΔP can be as follows:

[0084] First, calculate the required flow velocity v of the liquid in the pipe; where the flow rate is Q, m³ / s; the pipe radius is r, m; and the pipe cross-sectional area is A = πr², m².

[0085] Therefore, the flow velocity v is: v = Q / A, m / s.

[0086] Next, the Reynolds number (Re) is calculated, which is used to determine the flow regime (laminar or turbulent); where the density of the inlet medium is: ρ, kg / m3; the dynamic viscosity is: μ, 1 Pa·s = 1 kg / (m·s); and the diameter of the inlet pipe is: d, m.

[0087] Therefore, Re = (ρvd) / μ.

[0088] Next, determine the friction factor (f), and select the formula for calculating the friction factor f based on the flow regime:

[0089] When the flow is laminar, f = 64 / Re; when the flow is turbulent, the Colebrook equation is used.

[0090] Finally, calculate the friction loss (pressure drop ΔP), where the fluid density is ρ, kg / m³, and the straight pipe length is L, m.

[0091] Therefore, ΔP = f·(L / d)·(ρv² / 2).

[0092] Based on the magnitude of friction loss (pressure drop ΔP), determine whether the fluid can flow into the storage tank at a certain flow rate.

[0093] To quantitatively illustrate the technical effects of the present invention, comparative experiments are conducted below for verification.

[0094] First, the comparative examples reveal the shortcomings of existing technologies. Taking a commonly used peristaltic pump as an example, with a Tygon-1.52mm inner diameter pump tube, a pump tube length of 10cm, and operating at a speed of 35 rpm.

[0095] The volume of liquid discharged per revolution of a peristaltic pump is approximately: Vrev≈π×(d / 2)2×Leff, where d is the inner diameter, d=1.52mm, i.e., 0.152cm; and Leff is the pump tube length, approximately 10cm (the actual effective propulsion length is usually slightly less than the physical arc length, but if the pump head is designed compactly, this value can be used as an approximation).

[0096] Therefore, Vrev≈π×(0.076)2×10≈3.1416×0.005776×10≈0.1815mL / rev.

[0097] The theoretical initial flow rate is: Q0 = Vrev × rpm = 0.1815 mL / rev × 35 rpm ≈ 6.35 mL / min.

[0098] After 100 hours of operation, the pump tube was compressed, causing a change in its inner diameter. The measured inner diameter was approximately 1.48 mm. The flow rate at this time was as follows:

[0099] Vrev≈π×(0.076)2×10≈3.1416×0.005476×10≈0.1720mL / rev.

[0100] Therefore, the flow rate based on the measured inner diameter is: Q1 = Vrev × rpm = 0.1815 mL / rev × 35 rpm ≈ 6.02 mL / min.

[0101] After 300 hours of operation, the measured inner diameter is approximately 1.44 mm, and the flow rate at this time is as follows:

[0102] Vrev≈π×(0.07)2×10≈3.1416×0.0049×10≈0.1627mL / rev.

[0103] Therefore, the flow rate based on the measured inner diameter is: Q2 = Vrev × rpm = 0.1539 mL / rev × 35 rpm ≈ 5.70 mL / min.

[0104] Based on the above data, the rate of change in flow rate can be calculated as shown in the table below:

[0105] Time (hours) Flow rate (ml) Flow rate change (%) 0 <![CDATA[Q0=6.35]]> - 100 <![CDATA[Q1=6.02]]> 5.20 300 <![CDATA[Q2=5.70]]> 10.24

[0106] The calculation results above show that after the pump pipe has been running for a long time, the flow rate fluctuates continuously. This significant flow rate drift will inevitably lead to fluctuations in the analysis signal, which in turn affects the long-term stability and comparability of the test data.

[0107] Let's take a syringe pump as a specific example. Taking a 5mL syringe pump as an example, the actual time it takes to complete one "liquid aspiration-discharge" cycle can be about 14 seconds, which means that there is a periodic interruption in the liquid inlet flow path.

[0108] Assuming its rated stroke (piston travel distance) is 30mm; total control steps are 12000 steps; maximum motor speed is 800rpm; and lead screw pitch is 1mm / revolution; the theoretical time required to dispense 5mL of solution is calculated as follows:

[0109] First, calculate the total rotational speed, where the lead P = 1 mm / rev and the total stroke L = 30 mm.

[0110] Therefore, the required total motor revolutions are: Ntotal = L / P = 30mm / 1mm / rev = 30 revolutions.

[0111] Secondly, calculate the required theoretical time, where the maximum rotational speed n = 800 rpm, that is, 800 revolutions per minute.

[0112] Therefore, the required time is: t = Ntotal / n = (30 / 800) minutes = 0.0375 minutes, which is converted to seconds, so t = 0.0375 × 60 = 2.25 seconds.

[0113] The calculations above show that the theoretical time to dispense 5ml is 2.25 seconds, and the entire dispensing process takes 4.5 seconds. However, in actual equipment, due to acceleration / deceleration and safety flow limiting, the actual time to dispense 5ml is usually 3-10 seconds or longer. Based on this, we take the median dispensing time as 7 seconds, and the entire dispensing process takes 14 seconds. Therefore, when using a syringe pump for liquid injection, there will be a relatively long interval, making continuous liquid injection impossible, and water quality analysis cannot be performed quickly and continuously.

[0114] In stark contrast, the method of this invention can guarantee superior performance through theoretical calculation and design. In a specific design example, the inlet flow rate is set to Q = 5 mL / min, an inlet pipe with an inner diameter of d = 2.0 mm and a length of L = 1 m is used, the fluid is water, its medium density is ρ = 1000 kg / m3, and its dynamic viscosity is μ = 0.001 Pa·s = 0.001 kg / (m·s); the standard atmospheric pressure is taken as Patm = 101325 Pa.

[0115] Based on this, the influent flow rate can be calculated as: Q = 5 mL / min = 5 × 10 −6 m 3 / min=8.33×10 −8 m 3 / s; The cross-sectional area of ​​the pipe is: A=πr²=3.14159×(0.001)²≈3.14159×10⁻ 6 m².

[0116] Therefore, the flow velocity v is: v = Q / A ≈ 0.0265 m / s, and the Reynolds number Re is: Re = (ρvd) / μ = 53.

[0117] Based on the calculated Reynolds number, the fluid in the pipe is in a laminar flow state. Therefore, the formula for calculating the friction factor is the laminar flow formula, i.e., f=64 / Re=64 / 53≈1.2075.

[0118] Therefore, the friction loss (pressure drop ΔP) can be calculated as follows: ΔP = f·(L / d)·(ρv² / 2)≈212Pa.

[0119] Therefore, to ensure that the liquid flows into the storage tank at a flow rate of 5 mL / min, the pressure difference between the storage tank and atmospheric pressure must be at least 212 Pa. Based on this calculation, it can be seen that the negative pressure required to maintain a stable liquid inflow is extremely small, and the system can be easily and precisely controlled, thus eliminating the mechanical attenuation problem similar to that of a peristaltic pump in principle.

[0120] The absolute pressure inside the liquid storage chamber should be: Pbox = Patm - ΔP = 101325Pa - 212Pa ≈ 101113Pa. It is evident that the pressure inside the liquid storage chamber is essentially atmospheric pressure, indicating very low flow resistance. Therefore, to maintain a liquid inlet rate of 5 mL / min, the required pressure difference is extremely small; a pumping speed of >5 mL / min in the gas path module is sufficient. However, in practical applications, to ensure response speed and redundancy, the pumping speed of the vacuum pump in gas path module 4 is typically configured to be much greater than the theoretical minimum, for example, greater than 0.5 L / min.

[0121] In addition, the design of a single liquid storage tank with a volume of 4 liters and a switching liquid level of 3 liters (75%), with an inflow rate of 5 mL / min, calculates that the time required for the liquid storage tank to reach the set liquid level is 600 minutes, or 10 hours.

[0122] Therefore, it takes at least 10 hours for a single liquid storage tank to reach the set liquid level, which ensures normal measurement throughout the entire testing cycle and avoids frequent switching issues, further guaranteeing data stability.

[0123] In the dual-chamber alternating working mode, it can easily achieve more than 10 hours of uninterrupted continuous liquid injection, effectively solving the intermittent problem of injection pumps.

[0124] The solution of this invention allows for a longer detection cycle without the need for a terminal during the liquid injection process. During this time period, seamless switching between the two chambers enables truly continuous liquid injection. Only after one chamber completes its injection task is a waste removal process initiated in the background to empty it, while the injection process is continuously maintained by the other chamber, overcoming the inherent intermittent nature of syringe pumps.

[0125] Through quantitative comparison with traditional peristaltic pumps and syringe pumps, experimental data fully demonstrates that the liquid inlet device and method provided by this invention, through its unique negative pressure drive and dual-chamber alternating design, effectively solves the two major technical problems of "unstable flow rate during long-term operation" and "discontinuous liquid inlet process" in existing technologies. In terms of stability, it fundamentally avoids flow rate attenuation exceeding 10% caused by mechanical pump tube fatigue; in terms of continuity, it achieves uninterrupted liquid inlet capability for up to 10 hours. This significantly improves the data reliability, detection efficiency, and long-term operational stability of automatic water quality analyzers.

[0126] It should be noted that, for the sake of simplicity, the foregoing method embodiments are all described as a series of actions. However, those skilled in the art should understand that this application is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously according to this application. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to this application.

[0127] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0128] Those skilled in the art will understand that all or part of the steps in the various methods of the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, which may include: a flash drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk, etc.

[0129] The foregoing description is merely an exemplary embodiment of this disclosure and should not be construed as limiting the scope of this disclosure. Any equivalent changes and modifications made in accordance with the teachings of this disclosure shall still fall within the scope of this disclosure. Those skilled in the art will readily conceive of embodiments of this disclosure upon considering the specification and practicing the disclosure herein. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not described herein. The specification and embodiments are to be considered exemplary only, and the scope and spirit of this disclosure are defined by the claims.

Claims

1. An automatic water quality analysis and liquid feeding device, characterized in that, The liquid inlet device includes: The liquid circuit module (1) is provided with at least two liquid storage tanks, each of which is provided with a liquid inlet (12), a liquid outlet (13) and an air extraction port (11). The air circuit module (4) is used to provide controllable negative pressure, which includes a vacuum pump and a pressure control unit; A liquid valve (2) has an interface that is connected to at least two of the liquid storage tanks and reagent flow paths, and is used to switch the liquid inlet flow path; The gas valve (3) has an interface that is connected to at least two of the liquid storage tanks and the gas module (4) respectively, and is used to switch the gas flow path; An integrated control module (5) is electrically connected to the gas circuit module (4), the liquid circuit valve (2) and the gas circuit valve (3), and is used to control the output power of the gas circuit module (4) and the switching of the liquid circuit valve (2) and the gas circuit valve (3) according to the pressure feedback signal in the liquid storage tank; Waste liquid treatment module (6) is connected to the liquid outlet (13) and is used to discharge waste liquid; The integrated control module (5) is configured to control the synchronous switching of the liquid valve (2) and the gas valve (3) so that at least two of the liquid storage tanks alternately perform liquid inlet operation and waste discharge operation; Specifically, the liquid inlet operation involves applying negative pressure to the liquid storage chamber currently receiving liquid through the gas path module (4), so that the liquid to be analyzed or the reagent is continuously drawn in through the liquid inlet interface (12).

2. The automatic water quality analysis and liquid feeding device according to claim 1, characterized in that, The integrated control module (5) adjusts the power of the vacuum pump in real time through the pressure control unit to maintain the pressure stability in the liquid storage tank where the liquid is currently being injected, thereby ensuring a constant liquid flow rate.

3. The automatic water quality analysis and liquid feeding device according to claim 1, characterized in that, The operating parameters of the liquid inlet device meet the following conditions: the negative pressure ΔP generated by the gas circuit module (4) in the liquid storage tank is sufficient to overcome the total fluid resistance of the liquid inlet pipeline from the liquid inlet to the liquid storage tank.

4. The automatic water quality analysis and liquid feeding device according to claim 3, characterized in that, The negative pressure ΔP is calculated and set based on the friction factor, pipeline length, pipe diameter, fluid density, and flow velocity.

5. The automatic water quality analysis and liquid feeding device according to claim 1, characterized in that, The integrated control module (5) is also used to monitor the liquid level of the storage tank and control the switch to another storage tank when the liquid level of one storage tank reaches a preset threshold.

6. The automatic water quality analysis liquid feeding device according to claim 5, characterized in that, The preset threshold is set based on the effective volume of the liquid storage tank.

7. The automatic water quality analysis and liquid feeding device according to claim 1, characterized in that, The liquid valve (2) and the gas valve (3) are composed of a single valve body or a combination of multiple valve bodies.

8. An automated water quality analysis liquid feeding method, characterized in that, Continuous liquid feeding is performed using the liquid feeding device according to any one of claims 1 to 7, and the liquid feeding method includes the following steps: In the liquid inlet step, the liquid circuit valve (2) and the gas circuit valve (3) are controlled to connect the liquid inlet flow path and the gas extraction flow path to the first liquid storage tank. The gas circuit module (4) is started to apply negative pressure and continuously draw liquid into the first liquid storage tank. In the switching step, when the switching conditions are met, the liquid valve (2) and the gas valve (3) are switched synchronously to switch the liquid inlet flow path and the gas extraction flow path to the second liquid storage tank, and the liquid is continuously sucked into the second liquid storage tank. In the waste discharge step, the waste liquid treatment module (6) is started to discharge the waste liquid in the storage tank that has been filled with liquid.

9. The automatic water quality analysis liquid feeding method according to claim 8, characterized in that, The switching condition is that the liquid level in the first storage tank reaches a preset threshold, or the liquid inlet time reaches a preset duration.

10. A method for automatic water quality analysis and liquid feeding according to claim 8 or 9, characterized in that, During the liquid inlet step, the pressure in the liquid storage tank is monitored in real time, and the negative pressure output of the gas path module (4) is dynamically adjusted to stabilize the liquid inlet flow rate.

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