Device and method for detecting concentration of soluble gas in liquid

Abstract

The invention relates to the field of soluble gas detection, in particular to a device and a method for detecting the concentration of soluble gas in liquid. The water pipe seat is installed on a pipeline in series, the sealing ring and the breathable film are arranged between a water flow channel and the interior of a shell, the gas detection cavity is defined by the shell and a bottom plate, and the sensor module and the gas processing module are arranged in the gas detection cavity. To-be-detected liquid flows in the water pipe seat and is in contact with the water side surface of the gas-permeable membrane, soluble gas selectively penetrates through the gas-permeable membrane to enter the gas detection cavity, is enriched in a limited volume and is in contact with the gas treatment module, and the gas concentration is detected in real time by the sensor module. On-line calculation and display of the concentration of the soluble gas in the liquid are achieved through the pre-established mapping relation between the concentration of the gas in the gas detection cavity and the concentration of the soluble gas in the liquid, and the device has the advantages of being compact in structure, convenient to install, capable of preventing the sensor from making direct contact with the liquid, stable and reliable in detection result and the like.

Description

Technical Field

[0001] This invention relates to the field of soluble gas detection, specifically to a device and method for detecting the concentration of soluble gases in a liquid. Background Technology

[0002] In applications such as water treatment, circulating cooling, disinfection and sterilization, and drinking water monitoring, it is necessary to detect and control the concentration of soluble gases in liquids. Currently, three main detection principles are used in engineering projects:

[0003] The first type is the ultraviolet light absorption method, such as some online instruments that use mercury lamps as light sources. These instruments utilize the characteristic absorption peaks of the gas being measured at specific wavelengths and calculate the concentration from the absorbance based on the Lambert-Beer law. This type of equipment offers high measurement accuracy, but its optical system is large and expensive, requiring ample installation space and a stable power supply. Furthermore, mercury lamps have a limited lifespan and require regular replacement and maintenance, which is not conducive to long-term, low-cost operation.

[0004] The second category is the electrochemical sensor method, such as typical online residual chlorine / ozone control instruments. These instruments characterize concentration by generating a current signal through the reduction reaction of the analyte gas on the electrode surface. While these devices offer high resolution and fast response, the electrodes and their front-end membranes are in direct contact with the water for extended periods, making them susceptible to contamination, scaling, and corrosion from strong oxidizing components. This leads to electrode wear, sensitivity decay, and zero-point drift, requiring frequent cleaning, calibration, or replacement. Furthermore, other oxidizing substances in the water (such as residual chlorine) can interfere with the signal, making it difficult to guarantee selectivity and stability under complex water quality conditions.

[0005] The third category is chemical reagent methods, such as the DPD colorimetric method for measuring ozone concentration in water, the methylene blue colorimetric method for determining hydrogen sulfide concentration, and the phenolphthalein indicator colorimetric method for measuring carbon dioxide concentration. These methods use small, portable instruments suitable for on-site sampling, but they heavily rely on disposable reagents, leading to high reagent costs over long-term use. They also involve numerous operational steps, significant human intervention, and the results are easily influenced by operator error. Furthermore, they cannot achieve continuous online monitoring and struggle to reflect instantaneous fluctuations in the process. Overall, these three existing technologies have limitations in terms of equipment size, installation method, maintenance frequency, anti-interference capability, and the ability to achieve long-term online monitoring. They still cannot fully meet the comprehensive needs of engineering sites for compact structures, low maintenance, long-term stability, and real-time monitoring.

[0006] Therefore, there is an urgent need for a technical solution for detecting the concentration of soluble gases in liquids suitable for engineering sites. This solution should be as compact as possible in structure, easy to integrate with existing pipelines, and capable of continuous online monitoring of process liquids. In terms of detection mechanism, it should avoid long-term direct exposure of electrodes to complex aquatic environments, thus preventing pollution, scaling, and electrode consumption, and reducing maintenance frequency. In terms of performance, it should balance high measurement accuracy with good anti-interference capabilities, minimizing the impact of changes in water composition, oxidizing impurities, and environmental fluctuations on the detection results. Simultaneously, it should reduce reliance on disposable chemical reagents and manual operation, maintaining low operating costs and high stability during long-term operation to meet the needs of water treatment and related industries for real-time monitoring and refined control of the concentration of soluble gases in liquids. Summary of the Invention

[0007] The purpose of this invention is to provide a device and method for detecting the concentration of soluble gases in a liquid, so as to solve the technical problems mentioned in the background art.

[0008] Based on the above ideas, the present invention provides the following technical solution:

[0009] A device for detecting the concentration of soluble gases in a liquid includes: a water pipe seat, a sealing ring, a breathable membrane, a housing, a sensor module, a gas processing module, and a base plate;

[0010] The outer shell is made of plastic, and the floor is made of plastic base plate. The water pipe seat is installed at the upper end of the plastic outer shell, and a water flow channel is formed inside the water pipe seat for the liquid to be tested to flow through. The sealing ring and the breathable membrane are sequentially arranged between the water flow channel and the interior of the plastic outer shell. The sealing ring is used to seal the water flow channel and the gas detection chamber located below the breathable membrane. The breathable membrane is used to block the liquid to be tested while allowing soluble gases dissolved in the liquid to pass through, thereby allowing the soluble gases to enter the gas detection chamber. The plastic base plate is arranged at the lower end of the plastic outer shell. The plastic outer shell and the plastic base plate cooperate to form the gas detection chamber below the breathable membrane. The sensor module is arranged inside the gas detection chamber and is used to detect the concentration of soluble gases that escape from the liquid to be tested into the gas detection chamber through the breathable membrane. The gas processing module is arranged inside the gas detection chamber so that the soluble gases entering the gas detection chamber come into contact with the gas processing module.

[0011] By installing a water pipe seat at the upper end of the plastic casing and forming a water flow channel within the seat for the liquid to be tested, the device can be directly connected in series with the process pipeline, enabling online sampling and continuous flow of the liquid to be tested in a closed pipeline. A sealing ring and a permeable membrane are sequentially installed between the water flow channel and the inside of the plastic casing. The sealing ring ensures a reliable seal between the water and gas sides, while the permeable membrane provides liquid barrier while allowing gas permeation. This allows soluble gases dissolved in the liquid to selectively enter the lower gas detection chamber without allowing liquid to seep into the lower cavity. The plastic casing and plastic base plate, fitted together below the permeable membrane, form an independent... The gas detection chamber allows soluble gases that permeate through the breathable membrane to accumulate within a limited volume. A sensor module is installed within the gas detection chamber to directly detect the concentration of soluble gases escaping from the liquid being tested through the breathable membrane, avoiding contamination, corrosion, and drift problems caused by direct contact between the sensor and the liquid. Simultaneously, a gas processing module is installed within the gas detection chamber, allowing the soluble gases entering the chamber to come into contact with the gas processing module. This facilitates pretreatment, stabilization, or selective enhancement of the target gas, thereby improving the stability and reliability of the detection results and enabling indirect and accurate measurement of the concentration of soluble gases in the liquid.

[0012] Preferably, the device also includes a support frame, which is a metal support frame disposed on the side of the breathable membrane opposite to the water flow channel and connected to the plastic shell, for supporting and limiting the breathable membrane.

[0013] By using a metal support to provide in-plane support for the breathable membrane, bulging, collapse, and localized tearing of the membrane can be avoided under the impact of water flow, pressure fluctuations, or temperature changes. This ensures the compression and sealing effect between the breathable membrane, the water pipe seat, and the plastic shell. At the same time, the high structural strength of the metal support improves the mechanical reliability of the overall device, allowing the breathable membrane to maintain stable gas mass transfer performance during long-term online operation. This is beneficial for ensuring the stability of the mapping relationship between the gas concentration in the gas detection chamber and the concentration of soluble gases in the liquid.

[0014] Preferably, the metal support is provided with through holes corresponding to the breathable membrane, the through holes being used to provide a flow channel for soluble gases passing through the breathable membrane.

[0015] By designing the shape and size of the through holes, the effective gas channel area can be limited, making it easier to control the flux of soluble gas entering the gas detection chamber. This is beneficial for adjusting the response time and balancing the detection sensitivity and linear range. At the same time, the through hole structure can also reduce the dead space volume between the permeable membrane and the gas detection chamber, allowing the gas to diffuse rapidly to the detection area of ​​the sensor module on the underside of the membrane, thereby improving the device's response speed and detection efficiency to changes in the concentration of soluble gas in the liquid.

[0016] Preferably, the device also includes fixing screws and nuts, which are used to securely connect the water pipe seat to the plastic housing and the plastic housing to the plastic base plate. This ensures a reliable mechanical locking and sealing fit between the various components of the device.

[0017] Preferably, the sensor module is mounted on the plastic base plate, which serves as the mounting base for the sensor module.

[0018] By utilizing the electrical insulation properties of plastic materials, interference with the sensor circuitry can be avoided, thereby improving the reliability of the detection device in terms of electrical safety and long-term stable operation.

[0019] Preferably, the side wall of the plastic shell is provided with an opening that communicates with the outside, and the gas processing module is arranged inside the opening for contacting the soluble gas during the gas exchange process between the gas detection chamber and the outside.

[0020] On the one hand, it allows soluble gases that pass through the permeable membrane into the gas detection chamber to fully contact the gas processing module within the chamber, which is beneficial for adsorption, conversion, or stabilization of the target gas, thereby improving the selectivity and anti-interference capability of the sensor module. On the other hand, the combination of the side wall openings and the gas processing module allows the gas in the gas detection chamber to achieve equilibrium with the outside environment within a certain time scale, avoiding long-term deviation of the concentration in the detection chamber from the steady state due to gas accumulation or consumption, which is beneficial for improving the repeatability and long-term drift performance of the detection results.

[0021] A method for detecting the concentration of soluble gases in a liquid, using the aforementioned device for detecting the concentration of soluble gases in a liquid.

[0022] The detection method includes: S1, introducing a test liquid containing the soluble gas to be tested into the water pipe seat, allowing the test liquid to flow in the water flow channel formed within the water pipe seat and contact the water-side surface of the breathable membrane; S2, under the effect of the concentration difference across the breathable membrane, allowing the soluble gas dissolved in the test liquid to permeate through the breathable membrane and enter the gas detection chamber formed by the plastic shell and the plastic base plate below the breathable membrane, and contacting the gas processing module disposed within the gas detection chamber after entering the gas detection chamber; S3, using a sensor module disposed within the gas detection chamber to detect the gas concentration of the soluble gas within the gas detection chamber, obtaining the gas concentration of the soluble gas within the gas detection chamber; S4, calculating the concentration of the soluble gas in the test liquid based on the gas concentration of the soluble gas within the gas detection chamber and in conjunction with a pre-established mapping relationship between the gas concentration of the soluble gas within the gas detection chamber and the concentration of the soluble gas in the test liquid.

[0023] The method involves continuously flowing the liquid to be tested within a water-filled tube and contacting it with a breathable membrane. Utilizing the selective permeability of the membrane, soluble gases dissolved in the liquid are transferred to a gas detection chamber. Within this chamber, the gas is processed by a gas processing module and then detected in real-time by a sensor module. The concentration of the soluble gas in the liquid is calculated based on a pre-established mapping relationship between the gas concentration in the detection chamber and the concentration of the soluble gas in the liquid. This method combines gas-phase detection with liquid-phase concentration conversion, enabling online and continuous monitoring of the concentration of soluble gases in liquids without the need for adding reagents or offline sampling analysis. The process is simplified and highly automated. Furthermore, by calibrating the mapping relationship, the method can be adapted to different soluble gases and operating conditions, enhancing its versatility and engineering application value.

[0024] The workflow is as follows:

[0025] In scenarios requiring online monitoring of soluble gas concentrations in liquids, the operator connects the detection device of this invention in series with a water pipe socket on the process pipeline. The liquid to be tested flows stably through the water flow channel within the water pipe socket and covers the water-side surface of the permeable membrane. A sealing ring reliably isolates the water side and the gas side, ensuring that the liquid only contacts the permeable membrane and does not seep into the lower cavity. Driven by the concentration difference, the target soluble gas dissolved in the liquid gradually permeates through the permeable membrane and enters the gas detection chamber, enclosed by a plastic shell and a plastic base plate, through the opening in the metal support. Within this chamber, it fully contacts the gas processing module and achieves a stable gas phase concentration. The sensor module, fixed to the plastic base plate, detects the gas concentration in the gas detection chamber in real time and outputs an electrical signal, which is then converted by the host computer or control system to obtain the corresponding soluble gas concentration in the liquid. Throughout the process, fixing screws and nuts reliably lock the water pipe socket, plastic shell, and plastic base plate, ensuring that the permeable membrane and gas detection chamber are in a stable and sealed working state for a long period, thereby achieving continuous monitoring of the soluble gas concentration in the process liquid.

[0026] The technical solution of the present invention may include the following beneficial effects:

[0027] This invention constructs a gas-liquid isolation detection structure. The liquid to be tested flows only in the water flow channel inside the water pipe seat and comes into contact with the water-side surface of the breathable membrane. Under the joint constraint of the sealing ring, the outer shell, and the base plate, the breathable membrane reliably isolates the liquid from the gas detection chamber below, allowing only soluble gases dissolved in the liquid to selectively escape and accumulate within a limited volume. This avoids the pollution, corrosion, and zero-point drift problems caused by direct liquid contact with the sensor, ensuring a clean, stable, and controllable detection environment, and providing a basis for the indirect and accurate measurement of liquid phase concentration.

[0028] A detection method combining gas-phase detection and liquid-phase concentration conversion is proposed. This method transfers soluble gases dissolved in the liquid to a gas detection chamber via a permeable membrane. Under the action of the gas processing module, the sensor module detects the gas concentration in real time. Then, the concentration of soluble gases in the liquid phase is calculated using a pre-calibrated mapping relationship, achieving online, continuous, and automated monitoring of soluble gas concentrations in liquids. The entire process requires no chemical reagents and no offline sampling analysis, significantly simplifying the operation and reducing operating costs. Furthermore, the mapping relationship can be calibrated and adapted for different soluble gases and operating conditions, giving the same device good versatility and engineering application value. It is suitable for process monitoring of various liquid media, various soluble gases, and different process conditions. Attached Figure Description

[0029] Figure 1 This is an exploded view of Embodiment 1 of the device for detecting the concentration of soluble gases in a liquid according to the present invention.

[0030] Figure 2 This is a flowchart of Example 1 of a method for detecting the concentration of soluble gases in a liquid according to the present invention.

[0031] Figure 3 This is a flowchart of Example 2 of a method for detecting the concentration of soluble gases in a liquid according to the present invention.

[0032] In the diagram: 1. Fixing nut; 2. Water pipe seat; 3. Sealing ring; 4. Breathable membrane; 5. Metal bracket; 6. Plastic shell; 7. Fixing screw; 8. Sensor module; 9. Gas processing module; 10. Plastic base plate. Detailed Implementation

[0033] Example 1

[0034] like Figure 1 ,

[0035] A device for detecting the concentration of soluble gases in a liquid includes: a water pipe seat 2, a sealing ring 3, a breathable membrane 4, a housing, a sensor module 8, a gas processing module 9, and a base plate;

[0036] The outer shell is a plastic outer shell 6, and the floor is a plastic base plate 10;

[0037] Possible implementations of the gas treatment module 9 include: ultraviolet lamps, hot wires, catalysts, activated carbon, molecular sieves, metal-organic frameworks, and other adsorption materials.

[0038] In this embodiment, the gas processing module 9 is preferably a catalyst. The water pipe seat 2 is installed at the upper end of the plastic shell 6, and a water flow channel for the liquid to be tested to flow through is formed inside the water pipe seat 2. The sealing ring 3 and the breathable membrane 4 are sequentially disposed between the water flow channel and the interior of the plastic shell 6. The sealing ring 3 is used to seal the water flow channel and the gas detection chamber located below the breathable membrane 4. The breathable membrane 4 is used to block the liquid to be tested while allowing soluble gases dissolved in the liquid to permeate, thereby allowing the soluble gases to enter the gas detection chamber. The plastic base plate 10 is disposed at the lower end of the plastic shell 6, and the plastic shell 6 and the plastic base plate 10 cooperate to form the gas detection chamber below the breathable membrane 4. The sensor module 8 is disposed inside the gas detection chamber and is used to detect the concentration of soluble gases escaping from the liquid to be tested into the gas detection chamber via the breathable membrane 4. The gas processing module 9 is disposed inside the gas detection chamber, allowing the soluble gases entering the gas detection chamber to contact the catalyst.

[0039] By setting a water pipe seat 2 at the upper end of the plastic shell 6 and forming a water flow channel for the liquid to be tested to flow through the water pipe seat 2, the device can be directly connected in series with the process pipeline to realize online sampling and continuous flow of the liquid to be tested in a closed pipeline; by setting a sealing ring 3 and a breathable membrane 4 in sequence between the water flow channel and the inside of the plastic shell 6, the sealing ring 3 achieves a reliable seal between the water side and the gas side, and the breathable membrane 4 achieves liquid barrier while allowing gas to pass through, so that soluble gases dissolved in the liquid to be tested selectively enter the lower gas detection chamber without allowing liquid to seep into the lower cavity; the plastic shell 6 and the plastic base plate 10 are fitted together with the breathable membrane The gas detection chamber is formed below the permeable membrane 4, allowing soluble gases to accumulate within a limited volume. A sensor module 8 is installed inside the gas detection chamber, enabling it to directly detect the concentration of soluble gases escaping from the liquid under test through the permeable membrane 4. This avoids contamination, corrosion, and drift problems caused by direct contact between the sensor and the liquid. Simultaneously, a catalyst is placed inside the gas detection chamber, allowing the soluble gases entering the chamber to contact the catalyst. This facilitates the pretreatment, stabilization, or selective enhancement of the target gas, thereby improving the stability and reliability of the detection results and achieving indirect and accurate measurement of the concentration of soluble gases in the liquid.

[0040] Specifically, it also includes a support, which is a metal support 5. The metal support 5 is disposed on the side of the breathable membrane 4 away from the water flow channel and is connected to the plastic shell 6 to support and limit the breathable membrane 4.

[0041] By using the metal bracket 5 to provide in-plane support for the breathable membrane 4, bulging, collapse, and local tearing of the breathable membrane 4 can be avoided under the impact of water flow, pressure fluctuations, or temperature changes, ensuring the compression and sealing effect between the breathable membrane 4, the water pipe seat 2, and the plastic shell 6. At the same time, the high structural strength of the metal bracket 5 can improve the mechanical reliability of the overall device, enabling the breathable membrane 4 to maintain stable gas mass transfer performance during long-term online operation, which is beneficial to ensuring the stability of the mapping relationship between the gas concentration in the gas detection chamber and the concentration of soluble gas in the liquid.

[0042] Specifically, the metal support 5 is provided with through holes corresponding to the breathable membrane 4, and the through holes are used to provide a flow channel for soluble gases passing through the breathable membrane 4.

[0043] By designing the shape and size of the through holes, the effective gas channel area can be limited, making it easier to control the flux of soluble gas entering the gas detection chamber. This is beneficial for adjusting the response time and balancing the detection sensitivity and linear range. At the same time, the through hole structure can also reduce the dead space volume between the gas permeable membrane 4 and the gas detection chamber, allowing the gas to diffuse rapidly to the detection area of ​​the sensor module 8 on the underside of the membrane, thereby improving the device's response speed and detection efficiency to changes in the concentration of soluble gas in the liquid.

[0044] Specifically, it also includes a fixing screw 7 and a fixing nut 1, which are used to fix the water pipe seat 2 to the plastic housing 6 and the plastic housing 6 to the plastic base plate 10. This ensures a reliable mechanical locking and sealing fit between the various components of the device.

[0045] Specifically, the sensor module 8 is mounted on the plastic base plate 10, which serves as the mounting base for the sensor module 8.

[0046] By utilizing the electrical insulation properties of plastic materials, interference with the sensor circuitry can be avoided, thereby improving the reliability of the detection device in terms of electrical safety and long-term stable operation.

[0047] Specifically, the side wall of the plastic shell 6 is provided with an opening that communicates with the outside. The catalyst is arranged inside the opening and is used to contact the soluble gas during the gas exchange process between the gas detection chamber and the outside.

[0048] On the one hand, the soluble gas entering the gas detection chamber through the permeable membrane 4 is allowed to fully contact the catalyst within the chamber, which is beneficial for adsorption, conversion, or stabilization of the target gas, thereby improving the selectivity and anti-interference capability of the sensor module 8. On the other hand, the combination of side wall openings and the catalyst allows the gas in the gas detection chamber to achieve equilibrium with the outside world within a certain time scale, avoiding long-term deviation of the concentration in the detection chamber from the steady state due to gas accumulation or consumption, which is beneficial for improving the repeatability and long-term drift performance of the detection results.

[0049] A method for detecting the concentration of soluble gases in a liquid, using the aforementioned device for detecting the concentration of soluble gases in a liquid.

[0050] The detection method includes: S1, introducing a test liquid containing the soluble gas to be tested into the water pipe seat 2, allowing the test liquid to flow in the water flow channel formed within the water pipe seat 2 and contacting the water-side surface of the breathable membrane 4; S2, under the effect of the concentration difference on both sides of the breathable membrane 4, allowing the soluble gas dissolved in the test liquid to pass through the breathable membrane 4 and enter the gas detection chamber formed by the plastic shell 6 and the plastic base plate 10 below the breathable membrane 4, and contacting the gas processing module 9 disposed within the gas detection chamber after entering the gas detection chamber; S3, using the sensor module 8 disposed within the gas detection chamber to detect the gas concentration of the soluble gas within the gas detection chamber, obtaining the gas concentration of the soluble gas within the gas detection chamber; S4, calculating the concentration of the soluble gas in the test liquid based on the gas concentration of the soluble gas within the gas detection chamber and combined with a pre-established mapping relationship between the gas concentration of the soluble gas within the gas detection chamber and the concentration of the soluble gas in the test liquid.

[0051] The liquid to be tested flows continuously within the water pipe seat 2 and comes into contact with the breathable membrane 4. Utilizing the selective permeability of the breathable membrane 4, soluble gases dissolved in the liquid are transferred to the gas detection chamber. Within the gas detection chamber, the gas is processed by the gas processing module 9 and then detected in real time by the sensor module 8. The concentration of soluble gases in the liquid is then calculated based on a pre-established mapping relationship between the gas concentration in the gas detection chamber and the concentration of soluble gases in the liquid. This method combines gas-phase detection with liquid-phase concentration conversion, enabling online and continuous monitoring of the concentration of soluble gases in liquids without the need to add reagents to the liquid or perform offline sampling analysis. The operation process is simplified and highly automated. Furthermore, through the calibration of the mapping relationship, it can be adapted for different soluble gases and different operating conditions, improving the method's versatility and engineering application value.

[0052] Working principle:

[0053] The gas mapping relationship in S4 is formed by the following method:

[0054] In this embodiment, to convert the gas concentration measured by the sensor module within the gas detection chamber into the concentration of soluble gases in the liquid to be tested, a mathematical model based on mass transfer and gas-liquid equilibrium is established. First, the relevant physical quantities are defined as follows: the effective diffusion area of ​​the membrane is denoted as A. m The membrane mass transfer coefficient is denoted as k. m The volume of the gas detection chamber is denoted as V. g The amount of soluble gaseous substance detected in the chamber is n. g The partial pressure of soluble gas in the detection chamber is P. g The gas constant is R; the temperature is T; and the volume molar concentration of the soluble gas in the liquid being tested is C. L The volumetric molar concentration of the soluble gas in the gas detection chamber is C. g The flux through the permeable membrane is J; the mass transfer rate per unit time through the permeable membrane into the gas detection chamber is N.

[0055] First, based on the gas-liquid equilibrium relationship, the concentration C of the soluble gas in the liquid to be tested is determined. L Its equilibrium partial pressure P in the gas detection chamber below the permeable membrane g Henry's Law applies between them:

[0056] (1)

[0058] In the formula, H is the Henry's constant for the soluble gas in the liquid to be tested.

[0059] On the other hand, under the ideal gas assumption, the partial pressure P of the soluble gas in the gas detection chamber g Its mole number n g Volume V g The relationship is:

[0060] (2)

[0062] Divide both sides of equation (2) by V. g The relationship between the volumetric molar concentration and partial pressure within the gas detection chamber can be obtained:

[0063] (3)

[0065] Therefore, P g =C g Substituting RT into equation (1), we can obtain the basic mapping relationship between liquid phase concentration and gas phase concentration:

[0066] (4)

[0067] Equation (4) shows that, under the conditions of constant temperature and known Henry's constant H, the concentration C of soluble gas in the liquid to be tested is... L It is linearly proportional to the volumetric molar concentration Cg in the gas detection chamber, with a proportionality constant of HRT.

[0068] To describe the dynamic process of gas moving from the liquid phase through the permeable membrane into the gas detection chamber, a mass transfer model driven by the concentration difference across the permeable membrane is introduced. According to membrane mass transfer theory, the flux J through the permeable membrane can be expressed as:

[0069] (5)

[0071] In the formula, To determine the concentration C of the liquid phase at the gas-liquid interface L The equilibrium gas phase concentration. Since the membrane is not yet in equilibrium instantaneously, it can be assumed that... The actual concentration C in the detection chamber g There are certain differences between them. The total mass transfer rate N of the breathable membrane is:

[0072] (6)

[0074] In the gas detection chamber, a material balance is established for soluble gases: the cumulative amount of soluble gas in the chamber per unit time equals the amount introduced through the permeable membrane minus the amount consumed by the catalyst or leaked outwards within the chamber. The total consumption caused by the catalyst is considered as a change in concentration C. g The first-order apparent reaction has a rate constant of k. r Then we have:

[0075] (7)

[0077] In practical applications, through structural design and control of operating conditions, interface equilibrium can be established rapidly, thus it can be approximated. At this point, equation (7) can be simplified to:

[0078] (8)

[0080] make

[0081] (9)

[0083] Equation (8) can then be rewritten as a first-order linear ordinary differential equation:

[0084] (10)

[0086] With C g Using (0)=0 as the initial condition, we solve equation (10) to obtain the analytical solution of the change in the concentration of soluble gas in the gas detection chamber over time:

[0087] (11)

[0089] Among them, steady-state concentration:

[0090] (12)

[0092] From equations (11) and (12), it can be seen that when the detection time is long enough, i.e. At that time, the concentration inside the gas detection chamber tends to a steady-state value. In this embodiment, the device is calibrated experimentally to select a suitable sampling time before being put into use, so that the measurement time... satisfy In this case, the input formula (11) can be considered as Since the concentration is close to zero, the concentration inside the detection chamber can be approximated as the steady-state concentration. .

[0093] The electrical signal output by the sensor module is denoted as S. Within the linear operating region of the sensor, the output signal is related to the gas concentration C in the detection chamber. g They satisfy a linear relationship:

[0094] (13)

[0096] In the formula, α is the sensitivity coefficient and b is the zero-point offset, both of which can be determined by calibration experiments. Substituting equation (12) into equation (13), and combining... We can obtain:

[0097] (14)

[0099] Further processing can reduce the liquid phase concentration C. L Expressed as a function of the sensor output signal S:

[0100] (15)

[0102] in,

[0103] (16)

[0105] In summary, by using the gas mapping relationships constructed by equations (1) to (16), the output signal S of the sensor module can be collected in real time during the operation of the device, and the concentration C of soluble gas in the liquid to be tested can be calculated using equations (15) and (16). L Relevant parameters H, A m k m V g k r α, b H The mapping relationship can be determined one by one using standard liquids and standard gases of known concentrations before leaving the factory or during on-site calibration, thereby ensuring the accuracy of the mapping relationship and realizing the quantitative online monitoring of the concentration of soluble gases in liquids by the device of this invention.

[0106] Example 2

[0107] Based on Example 1, this example provides an optimized detection method for the concentration of soluble gas in a liquid. Steps S1 to S3 are the same as in Example 1, namely, the introduction and permeation of the liquid to be tested, the entry of the soluble gas into the gas detection chamber and its contact with the catalyst, and the real-time detection of the gas concentration in the gas detection chamber are completed respectively, and will not be described again.

[0108] Furthermore, in Example 2, S4 is refined by introducing temperature and pressure correction parameters and mass transfer kinetics correction parameters, and establishing a multi-parameter coupled gas-liquid mapping relationship by combining Henry's law and catalyst kinetics model. This improves the detection accuracy and robustness under different temperatures, pressures, flow rates, and reaction conditions, specifically including:

[0109] S4.1 After completing step S3, the gas detection chamber and related process parameters are first synchronously acquired. Specifically, this includes: reading the electrical signal S output by the sensor module at the current detection moment, and acquiring the temperature T and pressure P within the detection chamber using temperature and pressure sensors located in or near the gas detection chamber; simultaneously, obtaining the average flow velocity v of the liquid to be tested in the water flow channel within the water pipe seat based on the process control system or flow meter, and pre-determining or online measuring the density ρ, dynamic viscosity μ, and diffusion coefficient D of soluble gases in the liquid phase based on the composition of the liquid to be tested. L The above parameters are used for subsequent temperature and pressure corrections, mass transfer coefficient calculations, and kinetic corrections, providing basic data for establishing a physical mechanism-driven mapping relationship.

[0110] Step S4.1 makes this embodiment no longer limited to the output of a single sensor, but introduces multi-source process parameters that reflect thermodynamic and fluid dynamic states, laying the foundation for subsequent unified conversion of different working conditions.

[0111] S4.2, utilizing the sensor's sensitivity coefficient k under reference operating conditions. sAnd the zero-point offset S0, convert the current electrical signal S into nominal gas phase concentration. :

[0112]

[0113] Considering the temperature response characteristics of the sensor's sensitive material and the influence of temperature and pressure on volume fraction in the gas equation of state, this embodiment introduces a temperature correction index γ and a pressure correction index δ to construct an equivalent standard operating condition gas phase concentration parameter X, the expression of which is:

[0114]

[0115] Where T0 and P0 are the reference temperature and reference pressure during sensor calibration, respectively, and γ and δ are obtained by fitting from multi-point calibration experiments. Through the above temperature and pressure correction, the sensor output under different operating conditions can be uniformly converted into the equivalent gas phase concentration X under standard operating conditions, thereby reducing the direct impact of temperature and pressure fluctuations on the detection results.

[0116] S4.2, calculate the dimensionless parameters related to liquid-phase mass transfer and obtain the mass transfer correction parameter Y. To characterize the effect of liquid-phase mass transfer on the gas-liquid concentration mapping, based on the flow velocity v, density ρ, dynamic viscosity μ, and diffusion coefficient D obtained in step S4.1... L Combined with the hydraulic diameter d of the water flow channel inside the water pipe seat h Calculate the Reynolds number Re and the Schmidt number Sc:

[0117]

[0118]

[0119] Under the reference operating condition, the corresponding Reynolds number and Schmidt number are denoted as Re0 and Sc0, respectively, and the overall liquid-phase mass transfer coefficient is denoted as kL0. Using empirical correlations, this embodiment defines the liquid-phase mass transfer coefficient k under the current operating condition as... L Expressed as:

[0120]

[0121] Where the exponents n and m are the mass transfer exponents obtained through experimental fitting. The mass transfer correction parameter Y is further defined as:

[0122]

[0123] By performing dimensionless correction on the liquid phase mass transfer coefficient, parameter Y reflects the degree of enhancement or reduction in the liquid phase mass transfer capability under the current operating condition relative to the reference operating condition, providing a correction factor that matches the fluid dynamics for the subsequent accurate conversion of gas phase measurements into liquid phase concentration.

[0124] S4.4, constructing a temperature-dependent Henry's constant and catalyst kinetic correction, further considering the variation of the Henry's constant with temperature and the influence of gas consumption caused by the catalyst on the mapping relationship. Specifically, if the Henry's constant of the soluble gas in the test liquid at the reference temperature T0 is H0, then the Henry's constant H(T) at the current temperature is expressed by the empirical formula as:

[0125]

[0126] Wherein, β is the temperature coefficient obtained by fitting experimental data, used to reflect the exponential trend of solubility changing with temperature.

[0127] On the other hand, in this embodiment, the consumption of soluble gas within the gas detection chamber under the action of a catalyst is considered as a first-order apparent reaction, with an apparent rate constant of k at the reference temperature. r0 Combining the Arrhenius relation, the apparent rate constant k at the current temperature... r (T) can be represented as:

[0128]

[0129] Among them, E a Let R be the apparent activation energy and R be the gas constant. Through the above modeling, the degree of catalyst consumption in the gas phase at different temperatures can be quantified, allowing subsequent mapping relationships to consider both gas-liquid equilibrium and the catalytic decomposition process.

[0130] S4.5, a multi-parameter coupled gas-liquid mapping relationship is constructed based on the equivalent standard operating condition gas phase concentration parameter and the mass transfer correction parameter. In this embodiment, the aforementioned temperature and pressure corrected equivalent standard operating condition gas phase concentration parameter X, liquid phase mass transfer correction parameter Y, temperature-dependent Henry's constant H(T), and temperature-dependent apparent reaction rate constant k are used. r (T) is coupled to establish the liquid phase concentration C. L The calculation formula is as follows. Based on the material balance that the mass transfer input of the gas detection chamber equals the sum of the reaction consumption and external leakage under steady-state conditions, the relationship between the liquid phase concentration and the equivalent gas phase concentration can be approximated as follows:

[0131]

[0132] Where, kL=kL0Y, and λ is a proportionality coefficient related to the gas detection chamber volume, the effective area of ​​the permeable membrane, and the structural arrangement. L With k r Substituting the expression for (T) into the above equation, we get:

[0133]

[0134] Therefore, the liquid phase concentration CL It is a nonlinear function simultaneously affected by multiple physical quantities such as temperature, pressure, flow rate, viscosity, diffusion coefficient, and catalyst kinetics, with parameters X, Y, H(T) and k r A tangled relationship with clear physical significance is formed between (T).

[0135] S4.6, Calibration and Output of the Final Optimized Liquid Phase Concentration Results: To ensure the usability and accuracy of the above mapping relationship in engineering applications, this embodiment, before the device leaves the factory or during on-site commissioning, uses several sets of standard liquids with known soluble gas concentrations and corresponding operating conditions to complete the calibration of parameters γ, δ, n, m, β, k. r 0, E a , λ, k L0 The calibration of H0 establishes a parameter library that matches the device structure and specific application scenarios. During actual operation, the control system automatically completes data acquisition, parameter calculation, and mapping conversion according to steps S4.1 to S4.5 within each sampling cycle, and calculates the current liquid phase concentration C based on the above formula. L If necessary, moving averages or filtering can be applied to continuous samples to further suppress transient noise, ultimately resulting in a corrected C. L This is the output result of the concentration of soluble gases in the liquid being tested.

[0136] Through the above steps S4.1 to S4.6, this embodiment introduces a multi-parameter coupled mapping model based on temperature and pressure correction, fluid dynamics mass transfer correction, and catalyst kinetics correction, while maintaining the hardware structure of embodiment one. This enables the gas phase concentration measured in the gas detection chamber to be accurately and stably converted into liquid phase soluble gas concentration under different operating conditions, significantly improving the adaptability and detection accuracy of the method of the present invention under complex operating conditions.

[0137] This embodiment does not simply multiply the measured value in the gas detection chamber by a fixed coefficient, but rather integrates temperature, pressure, flow state, liquid properties, and catalyst reaction process into a single mapping model, allowing for organic coupling between various physical quantities. From a thermodynamic perspective, the solubility of gas in liquid changes significantly with temperature. This application does not use a fixed solubility parameter, but explicitly introduces the trend of solubility with temperature into the mapping relationship, so that signals measured under low and high temperature conditions can be automatically corrected to the correct solubility level. From a fluid dynamics and mass transfer perspective, the liquid's flow rate, density, viscosity, and the gas's diffusion ability in the liquid phase jointly determine the feed rate from the liquid phase to the membrane surface and the mass transfer capacity of the membrane interface. This application converts these factors into dimensionless parameters and further corrects the overall liquid phase mass transfer coefficient, so that the gas-liquid concentration difference across the membrane can be reasonably quantified under complex conditions such as steady flow, turbulent flow, viscosity changes, and formulation changes, thereby ensuring that the basic assumption of inferring the liquid phase concentration from the gas phase concentration always holds true.

[0138] Meanwhile, on the gas detection chamber side, this application does not simply assume that the gas is completely preserved within the chamber. Instead, it introduces a catalyst-induced decomposition process, treating the generation and consumption of gas within the detection chamber as a temperature-controlled first-order reaction, and combining this reaction rate with the aforementioned mass transfer capability. Thus, the equilibrium concentration within the detection chamber is no longer solely determined by gas-liquid equilibrium, but rather by multiple processes including liquid phase replenishment, membrane mass transfer, chamber retention, and catalytic decomposition. By simultaneously incorporating the solubility variation with temperature, the operating condition correction for liquid phase mass transfer capability, and the temperature dependence of the catalytic reaction rate into the mapping relationship, this application enables the same detection device to automatically compensate for various disturbances such as flow rate fluctuations, temperature fluctuations, system pressure changes, and catalyst activity decay through software-side modeling, outputting results highly consistent with the actual liquid phase concentration.

[0139] The technical benefits of this multi-parameter coupling design cannot be achieved by simply adding individual factors. On the one hand, the same hardware structure can cover various operating conditions with different temperatures, pressures, formulations, and flow rates, eliminating the need to design and calibrate a separate device for each condition, significantly reducing on-site deployment and maintenance costs. On the other hand, under complex conditions, traditional linear calibration methods based solely on a single proportionality coefficient often produce systematic deviations under high concentrations or extreme conditions. This application, however, uses a physical mechanism-driven mapping model to explicitly expose these hidden variables as calculable parameters, suppressing measurement errors at their source. In long-term online monitoring scenarios, the model can also update key parameters through periodic calibration, ensuring stable output even as catalyst activity gradually declines and the liquid system undergoes slight changes. Therefore, this application does not simply add a few correction factors, but rather, through joint modeling of thermodynamics, mass transfer, and reaction kinetics, enables the gas detection device to exhibit significantly superior accuracy, robustness, and universality compared to traditional linear mapping schemes under different operating conditions.

Claims

1. A device for detecting the concentration of soluble gases in a liquid, characterized in that, include: The system comprises a water pipe seat (2), a sealing ring (3), a breathable membrane (4), a housing, a sensor module (8), a gas processing module (9), and a base plate. The water pipe seat (2) is installed on the upper end of the housing, and a water flow channel for the liquid to be tested is formed inside the water pipe seat (2). The sealing ring (3) and the breathable membrane (4) are sequentially arranged between the water flow channel and the inside of the housing. The sealing ring (3) is used to seal the water flow channel and the gas detection chamber located below the breathable membrane (4). The breathable membrane (4) is used to block the liquid to be tested while allowing soluble gases dissolved in the liquid to be tested. The gas permeates through the gas, allowing the soluble gas to enter the gas detection chamber. The base plate is located at the lower end of the outer shell, and the outer shell and the base plate cooperate to form the gas detection chamber below the permeable membrane (4). The sensor module (8) is located inside the gas detection chamber and is used to detect the concentration of soluble gas that escapes from the liquid to be tested into the gas detection chamber through the permeable membrane (4). The gas processing module (9) is located inside the gas detection chamber, so that the soluble gas entering the gas detection chamber comes into contact with the gas processing module (9), thereby playing the role of gas adsorption, decomposition, and transfer.

2. The device for detecting the concentration of soluble gases in a liquid according to claim 1, characterized in that, It also includes a bracket, which is disposed on the side of the breathable membrane (4) away from the water flow channel and connected to the outer shell, for supporting and limiting the breathable membrane (4).

3. The device for detecting the concentration of soluble gases in a liquid according to claim 2, characterized in that, The support is provided with through holes corresponding to the breathable membrane (4), and the through holes are used to provide a flow channel for soluble gases to pass through the breathable membrane (4).

4. The device for detecting the concentration of soluble gases in a liquid according to claim 3, characterized in that, It also includes a fixing screw (7) and a fixing nut (1), which are used to fix the water pipe seat (2) to the outer shell and the outer shell to the base plate.

5. The device for detecting the concentration of soluble gases in a liquid according to claim 4, characterized in that, The sensor module (8) is mounted on the base plate, which serves as the mounting base for the sensor module (8).

6. The device for detecting the concentration of soluble gases in a liquid according to claim 5, characterized in that, The outer shell has an opening on its side wall that communicates with the outside. The gas processing module (9) is arranged inside the opening and is used to contact the soluble gas during the gas exchange process between the gas detection chamber and the outside.

7. The method for detecting the concentration of soluble gases in a liquid according to claim 6, characterized in that, Using the detection device for the concentration of soluble gases in a liquid as described in any one of claims 1-6, The detection method includes: S1, introducing a test liquid containing the soluble gas to be tested into the water pipe seat (2), allowing the test liquid to flow in the water flow channel formed in the water pipe seat (2) and contacting the water-side surface of the breathable membrane (4); S2, under the action of the concentration difference on both sides of the breathable membrane (4), allowing the soluble gas dissolved in the test liquid to pass through the breathable membrane (4) and enter the gas detection chamber formed by the outer shell and the bottom plate below the breathable membrane (4), and after entering the gas detection chamber, contacting the water-side surface of the breathable membrane (4). S3, the gas processing module (9) in the gas detection chamber is in contact; the sensor module (8) installed in the gas detection chamber is used to detect the gas concentration of soluble gas in the gas detection chamber to obtain the gas concentration of soluble gas in the gas detection chamber; S4, based on the gas concentration of soluble gas in the gas detection chamber and combined with the pre-established mapping relationship between the gas concentration of soluble gas in the gas detection chamber and the concentration of soluble gas in the liquid to be tested, the concentration of soluble gas in the liquid to be tested is calculated.

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