An online trace moisture analyzer and detection method based on dual detection modes

Abstract

This invention discloses an online trace moisture analyzer and detection method based on dual detection modes. The analyzer includes an explosion-proof cabinet, a PLC control system, and a positive pressure control system. The explosion-proof cabinet includes an analysis cabinet and an electrical control box. The analysis cabinet contains an analysis component, which includes a detection component and a reagent supply component. The detection component includes an electrolytic photometric detection device and a liquid inlet device. The electrolytic photometric detection device includes an electrolytic detection device, a photometric detector, and a stirring module. The electrolytic detection device has an electrolytic electrode and a potential electrode. The photometric detector includes a detector housing containing the electrolytic detection device and having a light source emitting module and a light receiving module symmetrically arranged on the lower middle sidewall, and a base located in the lower part of the housing with a weighing sensor at the bottom. The liquid inlet device includes a manifold valve plate assembly connected to the pipeline of the electrolytic detection device, a reagent pump, and a feed pump. This invention achieves detection and analysis with dual detection modes, which is accurate, efficient, and widely applicable.

Description

Technical Field

[0001] This invention relates to the field of trace moisture detection and analysis technology, specifically to an online trace moisture analyzer and detection method based on dual detection modes. Background Technology

[0002] Many products or their manufacturing processes have extremely high requirements for moisture content. Excessive moisture content not only renders products substandard but can also pose safety hazards. For example, the moisture content requirements in the fluorination industry and lithium-ion electrolytes are extremely high. Fluorinated liquids, in particular, have very strict moisture control; exceeding the specified limits can trigger a series of serious chemical reactions and equipment problems, directly impacting product quality and production safety. Furthermore, moisture can react with lithium salts (such as LiPF6) in the fluorinated liquid to produce highly corrosive hydrofluoric acid (HF), which corrodes metal components, leading to equipment damage, leaks, and increased maintenance costs. In new energy batteries, the presence of trace amounts of moisture exceeding 20 ppm in lithium-ion electrolytes can cause the decomposition of lithium hexafluorophosphate, generating HF. This HF further exacerbates the decomposition of lithium hexafluorophosphate, leading to internal corrosion of the battery. This significantly impacts battery capacity, cycle life, and safety. Therefore, the detection and control of trace moisture in fluorinated liquids and lithium-ion battery electrolytes is crucial.

[0003] Currently, common methods for detecting trace moisture include gas chromatography, photometric detection, and Karl Fischer method. However, gas chromatography is limited by the sensitivity of the TCD detector, resulting in low accuracy and making it unsuitable for detecting trace moisture in electrolytes used in electrochemical devices. Photometric detection relies on the difference in light absorption before and after adding the test liquid to determine moisture content. When the moisture content in the test liquid is relatively low, the color change is relatively obvious, with a large change in light value, leading to relatively accurate detection. Conversely, when the moisture content is relatively high, the color change is less noticeable, resulting in inaccurate detection. The Karl Fischer coulometric method is suitable for determining trace moisture in various environments. It is applied in trace moisture detection scenarios such as lithium battery electrolytes, specialty gases, and transformer oil due to its advantages of not requiring frequent reagent changes, fast detection speed, and high sensitivity. However, the Karl Fischer method is currently commonly used for offline determination, requiring manual sample delivery and analysis, and the time from sampling to laboratory analysis results is considerable. Generally, it takes more than 2 hours to measure liquids with extremely low moisture content. This is not only time-consuming and unable to provide timely feedback on the sample liquid, but also affects the accuracy of the detection due to the limited current detection resolution of the instrument caused by the small amount of electricity required for electrolysis. There has been research on Karl Fischer coulometric online analysis devices, but these have complex structures and large volumes of inlet and outlet devices and detection devices. The quantitative, inlet and outlet, and cleaning operations for sample liquid and reagents are numerous, quantitative analysis is time-consuming, and accuracy cannot be fully guaranteed. Moreover, simple desiccants are often used for water removal, which cannot completely prevent water absorption by Karl Fischer reagents and sample liquids during the detection process, thus further affecting the detection accuracy. Furthermore, moisture detection is time-consuming and inefficient. Therefore, there is a need to develop an online analyzer that can quickly and efficiently detect liquids containing trace amounts of moisture at different concentrations by switching between different detection modes. This analyzer should be sensitive, accurate, compact, easy to operate, and suitable for compact layouts, safety requirements, and long-term use in chemical production sites. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the purpose of this invention is to provide an online trace moisture analyzer and detection method based on dual detection modes, in order to meet the need for rapid and high-precision detection of liquids containing trace moisture of different concentrations, and to achieve fully automated online detection, thereby improving efficiency.

[0005] The technical solution adopted by this invention to solve its technical problem is: An online trace moisture analyzer based on dual detection modes includes an explosion-proof cabinet, a PLC control system, and a positive pressure control system. The explosion-proof cabinet includes an analysis cabinet located at its lower part and an electrical control box located above the analysis cabinet. The PLC control system includes a PLC controller installed inside the electrical control box. An analysis component is installed inside the analysis cabinet. The analysis component includes a detection component located at the upper part of the analysis cabinet and a reagent supply component at the bottom of the analysis cabinet for supplying Karl Fischer reagent and anhydrous ethanol to the detection component. The detection component includes an electrolytic photometric detection device located above the reagent supply component and a liquid inlet device fixed inside the analysis cabinet. The electrolytic photometric detection device includes reagent and sample inlet... The system includes a discharge port, an electrolytic detection device that can hold sample liquid and reagents and is equipped with a potential electrode for detecting potential, an electrolytic electrode for electrolyzing water, a photometric detector located below the electrolytic detection device to support it, a photometric detector with a light source emitting module and a light receiving module symmetrically arranged internally and equipped with a weighing sensor, and a stirring module for stirring the sample liquid and reagents. The liquid inlet device includes a manifold valve plate assembly connected to the electrolytic detection device through a pipeline, and a reagent pump and a feed pump connected to the manifold valve plate assembly through a pipeline. The analysis cabinet is also equipped with a sampling component connected to the feed pump through a pipeline. The electrolytic photometric detection device, the liquid inlet device, the sampling component, and the PLC controller are connected by wires.

[0006] Furthermore, the PLC control system also includes a touch screen installed on the front door of the electrical control box and supporting software running on the touch screen and the PLC controller. The electrical control box also contains a switching power supply, a power switch, and an internal wiring assembly for connecting external wires and connecting to the PLC controller and the positive pressure control system via wires. An explosion-proof wiring port is provided on one outer wall of the electrical control box.

[0007] Furthermore, the reagent supply assembly includes a Karl Fischer reagent bottle containing Karl Fischer reagent, an ethanol reagent bottle containing anhydrous ethanol, and a first gas dehydrator connected to the Karl Fischer reagent bottle and the ethanol reagent bottle via pipelines. The electrolysis detection device and the manifold valve plate assembly are also connected to the second gas dehydrator fixed inside the analysis cabinet via pipelines.

[0008] Furthermore, the electrolytic detection device includes an electrolytic vessel containing sample liquid and reagents. The electrolytic electrode and potential electrode are inserted into the top of the electrolytic vessel and extend into the interior of the electrolytic vessel. The top of the electrolytic vessel is also provided with an air vent connected to the second gas dehydrator via a pipeline and an inlet / outlet connected to the manifold valve plate assembly via a pipeline. A magnetic stir bar is provided inside the electrolytic vessel. A manual liquid filling port is also provided on one side wall of the electrolytic vessel, and a manual liquid filling port plug is provided on the manual liquid filling port. The photometric detector includes a detector housing for placing an electrolysis detection device and a base disposed inside the lower part of the detector housing. The detector housing is a hollow shell and is fixed to the analysis cabinet. The light source emitting module and the light receiving module are symmetrically installed on the side wall of the lower middle part of the detector housing. A terminal post is provided on one outer wall of the detector housing. The upper shell wall of the detector housing is provided with a locking groove for locking the manual liquid filling port of the electrolysis tank. A base plate is fixed to the bottom of the detector housing. The base is fixedly installed on the base plate. The upper part of the base is a tray for placing the electrolysis detection device, and the lower part is equipped with a stirring motor with a magnet installed at the output end. The weighing sensor is installed at the bottom of the base. The potential electrode, electrolytic electrode, light source emitting module, light receiving module, weighing sensor, stirring motor, and terminal block are connected by wires, and are also connected to the PLC controller via wires through the terminal block.

[0009] Furthermore, the manifold assembly includes a stainless steel connector seat, a stainless steel valve seat, and a PTFE sealing gasket with several through-flow grooves fixedly pressed between the stainless steel connector seat and the stainless steel valve seat; a feed three-way solenoid valve, a metering three-way solenoid valve, an ethanol feed three-way solenoid valve, and a Karl Fischer feed three-way solenoid valve are fixedly installed on the stainless steel valve seat, and the feed three-way solenoid valve, metering three-way solenoid valve, ethanol feed three-way solenoid valve, and Karl Fischer feed three-way solenoid valve are connected to the PLC controller via wires. The stainless steel valve seat is provided with three interface through holes that communicate with the feed three-way solenoid valve, the metering three-way solenoid valve, the ethanol feed three-way solenoid valve and the Karl Fischer feed three-way solenoid valve. The stainless steel connector seat is provided with a feed through hole, a detector through hole, a first reagent pump through hole, a recovery through hole, a second reagent pump through hole, a first quantitative tube connection through hole, a second quantitative tube connection through hole, an ethanol through hole, and a Karl Fischer through hole. The through-flow channels on the PTFE gasket include a feed pump channel, a detector channel, a recovery channel, a reagent pump channel, an ethanol channel, a Karl Fischer channel, and a first intermediate channel, a second intermediate channel, a third intermediate channel, a fourth intermediate channel, and a fifth intermediate channel, all extending through its thickness direction. The feed pump channel and the detector channel are integrally located on opposite sides of the same end of the first intermediate channel, with each having one end adjacent to that end of the first intermediate channel. The recovery channel and the reagent pump channel are integrally located on opposite sides of the same end of the second intermediate channel, with each having one end adjacent to that end of the second intermediate channel. The detector channel, reagent pump channel, ethanol channel, and Karl Fischer channel are located on one side of the same long side of the PTFE gasket. The detector channel and the reagent pump channel are adjacent to each other and arranged sequentially from the outside to the inside along the length direction of the PTFE gasket, starting from the position closest to one side of the wide side. The adjacent ends of the feed pump channel, the detector channel, and the first intermediate channel are respectively connected to the three ports of the feed three-way solenoid valve through corresponding interface holes on the stainless steel valve seat. The other end of the feed pump channel is connected to the feed pump through the feed through hole via a pipeline. The other end of the detector channel is connected to the inlet and outlet of the electrolysis tank through the detector through the detector through the through hole via a pipeline. The adjacent ends of the recovery channel, the reagent pump channel, and the second intermediate channel are respectively connected to the three ports of the quantitative three-way solenoid valve through corresponding interface holes on the stainless steel valve seat. The other end of the recovery channel is connected to the externally installed recovery tank through the recovery through the recovery through hole via a pipeline. The other end of the reagent pump channel is connected to the output end of the reagent pump through the first through hole of the reagent pump via a pipeline. The third intermediate flow channel is connected to one end of the ethanol flow channel and one end of the fourth intermediate flow channel, and is connected to the three ports of the ethanol feed three-way solenoid valve through corresponding interface holes on the stainless steel valve seat. The other end of the third intermediate flow channel is connected to the input end of the reagent pump through the second through hole of the reagent pump via a pipeline. The other end of the ethanol flow channel is connected to the ethanol reagent bottle through a pipeline through an ethanol through hole. The other end of the fourth intermediate flow channel, one end of the Karl Fischer flow channel, and one end of the fifth intermediate flow channel are adjacent to each other and are connected to the three ports of the Karl Fischer feed three-way solenoid valve through corresponding interface holes on the stainless steel valve seat. The other end of the Karl Fischer flow channel is connected to the Karl Fischer reagent bottle through a Karl Fischer through hole via a pipeline. The other end of the first intermediate flow channel, which is not adjacent to the flow channel of the feed pump and the flow channel of the detector, is connected to the first through hole of the quantitative tube. The other end of the second intermediate flow channel, which is not adjacent to the flow channel of the recovery channel and the flow channel of the reagent pump, is connected to the second through hole of the quantitative tube. A spiral pipe is connected between the first through hole of the quantitative tube and the second through hole of the quantitative tube. The two sides of the long side of the stainless steel connector are respectively provided with an air inlet channel and a waste liquid discharge channel that communicate with both ends of the fifth intermediate flow channel. The air inlet channel and the through hole of the detector are located on the same half of the stainless steel connector, and the inlet of the air inlet channel is opened on the long side of this side and is connected to the second gas dehydrator through a pipeline. The outlet of the air inlet channel is opened on the surface of the stainless steel connector that is in contact with the PTFE sealing gasket and is connected to the other end of the fifth intermediate flow channel. The waste liquid discharge channel and the feed through hole are located on the same half of the stainless steel connector, and the outlet of the waste liquid discharge channel is opened on the long side of this side and is connected to the waste liquid pool through a pipeline. The inlet of the waste liquid discharge channel is opened on the surface of the stainless steel connector that is in contact with the PTFE sealing gasket and is connected to one end of the fifth intermediate flow channel. The feed three-way solenoid valve is synchronized with the feed pump, and the quantitative three-way solenoid valve is synchronized with the externally installed recovery tank; the feed three-way solenoid valve is synchronized with the electrolytic photometric detection device, and the quantitative three-way solenoid valve is synchronized with the reagent pump.

[0010] Furthermore, the feed through-hole, detector through-hole, reagent pump first through-hole, recovery through-hole, reagent pump second through-hole, quantitative tube connection first through-hole, quantitative tube connection second through-hole, ethanol through-hole, and Karl Fischer through-hole are composed of two parts: a smooth through-hole section and a through-hole section with internal threads connected to the smooth through-hole section. The smooth through-hole section is located on the side that is in contact with the PTFE gasket and is connected to the feed pump channel, detector channel, reagent pump channel, recovery channel, third intermediate channel, first intermediate channel, second intermediate channel, ethanol channel, and Karl Fischer channel, respectively. The through-hole section with internal threads is located on the side away from the PTFE gasket and is connected to the feed pump, electrolytic photometric detection device, reagent pump output end, recovery tank, reagent pump input end, both ends of the spiral pipe, ethanol reagent bottle, and Karl Fischer reagent bottle through pipelines. The smooth through-hole section and the through-hole section with internal threads are sealed together, and the inner diameter of the through-hole section with internal threads is larger than the inner diameter of the smooth through-hole section. Both the air intake channel and the waste liquid discharge channel consist of an L-shaped smooth inner hole section directly connected to the fifth intermediate flow channel and an internally threaded hole section connected to the L-shaped smooth inner hole section. The internally threaded hole section of the air intake channel is connected to the second gas dehydrator through a pipeline, and the internally threaded hole section of the waste liquid discharge channel is connected to the waste liquid pool through a pipeline. The L-shaped smooth inner hole section and the internally threaded hole section of the air intake channel and the waste liquid discharge channel are sealed together, and the inner diameter of the internally threaded hole section is larger than the inner diameter of the L-shaped smooth inner hole section.

[0011] Furthermore, the sampling assembly includes a sampling valve disposed on one outer wall of the analysis cabinet and connected to the input end of the feed pump via a pipeline, a pneumatic solenoid valve connected to the control end of the sampling valve via a pipeline and controlling the opening and closing of the sampling valve, and a sampling pressure reducing valve connected to the other end of the pneumatic solenoid valve to control the airflow pressure of the pneumatic solenoid valve, the other end of the sampling pressure reducing valve being connected to compressed gas; both ends of the sampling valve are respectively connected to the production pipeline via pipelines.

[0012] Furthermore, the positive pressure control system is installed on the other side of the analysis cabinet. The positive pressure control system includes a positive pressure controller installed on the other side of the analysis cabinet, a positive pressure control solenoid valve connected to the positive pressure controller and controlled to open and close by the positive pressure controller, a positive pressure control pressure reducing valve connected to one end of the positive pressure control solenoid valve, a flow regulating valve provided on the positive pressure control solenoid valve, the other end outlet of the flow regulating valve is located inside the explosion-proof cabinet, and the other end of the positive pressure control pressure reducing valve is connected to compressed nitrogen. The positive pressure control system also includes a pressure sensor installed inside the analysis cabinet. The positive pressure controller and the positive pressure control solenoid valve are connected to the internal wiring assembly inside the electrical control box via wires.

[0013] Furthermore, a mounting ring is installed on the lower inner side wall of the detector housing. An annular vertical rack is provided on the upper inner section of the mounting ring. The light source emitting module and the light receiving module are mounted on the upper end face of the mounting ring. A drive motor is installed on the light source emitting module and the light receiving module respectively. A gear that meshes with the annular vertical rack on the upper inner section of the mounting ring is installed on the output end of the drive motor. Two mounting ring lifting cylinders are symmetrically installed below the mounting ring. The mounting ring lifting cylinders are integrally mounted on the inner side wall of the lower part of the detector housing. The output end of the mounting ring lifting cylinder is connected to the lower end face of the mounting ring.

[0014] This invention also provides a method for detecting trace moisture content using an online trace moisture analyzer based on dual detection modes, comprising the following steps: S1: Dehydration: The first and second gas dehydrators operate to remove moisture from the Karl Fischer reagent bottles, ethanol reagent bottles, and electrolysis tanks; S2: Wiring: Connect the wires through the explosion-proof wiring port to the wiring assembly inside the electrical control box to ensure reliable wiring between the wiring assembly inside the box and the PLC controller and the positive pressure control system; S3: Confirm that the pipelines between the reagent supply component, electrolytic photometric detection device, liquid inlet device, second gas dehydrator, and sampling component are installed and connected correctly, the relevant pipeline lengths for sampling meet the requirements, the pipeline joints are not loose, and the materials flow normally without leakage. S4: Accurately prepare Karl Fischer reagent and anhydrous ethanol into Karl Fischer reagent bottle and ethanol reagent bottle, respectively; S5: Power On and Positive Pressure Regulation: Turn on the power switch to power on the reagent pump, feed pump, electrolytic photometric detection device, positive pressure control system, and sampling components, ensuring that the potential electrode, stirring motor, and weighing sensor are in working condition; the positive pressure controller regulates the gas positive pressure protection of the explosion-proof cabinet, connects nitrogen to the gas inlet of the positive pressure control pressure reducing valve, and after the pressure is reduced by the positive pressure control pressure reducing valve, adjusts the flow regulating valve to ensure that the gas pressure entering the explosion-proof cabinet meets the process requirements; S6: Injecting Karl Fischer reagent into the electrolysis tank: The feed three-way solenoid valve controls the first intermediate flow channel to connect with the detector flow channel, while the quantitative three-way solenoid valve controls the second intermediate flow channel to connect with the reagent pump flow channel. The ethanol feed three-way solenoid valve controls the third and fourth intermediate flow channels to connect, and the Karl Fischer feed three-way solenoid valve controls the fourth intermediate flow channel to connect with the Karl Fischer flow channel. The reagent pump runs in the forward direction, injecting Karl Fischer reagent into the electrolysis tank. The stirring motor drives the magnetic stir bar to stir the reagent in the electrolysis tank. When the weighing sensor shows that the set weight has been reached, the Karl Fischer feed three-way solenoid valve controls the fourth intermediate flow channel and the Karl Fischer flow channel to disconnect and connect with the fifth intermediate flow channel. Nitrogen gas dried by the second gas dehydrator is introduced from the other end of the fifth intermediate flow channel through the air inlet channel, injecting all the remaining Karl Fischer reagent in the pipeline into the electrolysis tank. The equilibrium potential of the Karl Fischer reagent in the electrolysis vessel is set to A, and the allowable deviation of the potential value is ±b, where b>0. After the Karl Fischer reagent is added, when the potential electrode detects that the potential value of the Karl Fischer reagent exceeds (A+b), the PLC controller controls the electrolysis electrode to work, decompose the water in the Karl Fischer reagent, and reduce the potential value of the Karl Fischer reagent to the range of (Ab)~(A+b), so that the Karl Fischer reagent is in an electrolytic equilibrium state, which meets the condition of the sample-ready liquid. At this time, the light source emitting module is activated to emit light, and the light receiving module receives the light emitted by the light source emitting module after passing through the Karl Fischer reagent in the electrolysis tank. The PLC controller records the light value received by the light receiving module at this time. S7: Adding sample solution to the electrolysis tank: The feed three-way solenoid valve first controls the connection between the first intermediate flow channel and the feed pump flow channel, while the quantitative three-way solenoid valve controls the connection between the second intermediate flow channel and the recovery flow channel. The sampling valve is opened, and the feed pump works. Sample solution is first introduced into the feed pump flow channel, the first intermediate flow channel, the recovery flow channel, the second intermediate flow channel, and the spiral pipe for a certain period of time to perform material replacement. After the replacement is completed, sample solution is introduced again for a certain period of time. Then, the feed three-way solenoid valve controls the connection between the first intermediate flow channel and the detector flow channel, while the quantitative three-way solenoid valve controls the connection between the second intermediate flow channel and the reagent pump flow channel. The ethanol feed solenoid valve controls the connection between the third and fourth intermediate flow channels, and the Karl Fischer feed three-way solenoid valve controls the connection between the fourth and fifth intermediate flow channels. The reagent pump runs in the forward direction. Under the action of the dried nitrogen gas introduced through the air inlet channel, a quantitative sample solution in the spiral pipe is pumped into the electrolysis tank. S8: Segmented detection and analysis: Let c be a value greater than b. The water content of the liquid is divided into two intervals in advance. After the sample liquid is added to the electrolysis tank, the potential value of the mixed liquid after the sample liquid is added is within the range of (A+b) to (A+c). This is the low water content segment. The potential value of the mixed liquid after the sample liquid is added is within the range of (A+b) to (A+c). This is the high water content segment. When the potential value is displayed in the low moisture content range after the sample solution is added, the system automatically starts the photometric detection method. The light source emission module emits light, and the light receiving module receives the light passing through the mixed liquid in the electrolysis tank. The PLC controller records the light value received by the light receiving module at this time, and calculates the moisture content in the sample solution based on the difference in light value before and after the sample solution is added. After the detection is completed, the electrolysis electrode is activated to bring the potential value of the mixed liquid back to the equilibrium state and wait for the next detection. When the potential value is displayed in the high moisture content range after the sample solution is added, the system automatically starts the Karl Fischer coulometric method, the electrolysis electrode is activated, the PLC controller collects the electrolysis current signal in real time, and integrates the current over time to obtain the total electrolysis charge Q that brings the potential value back to equilibrium. The system then automatically calculates the moisture content in the sample solution according to the following formula: ; Wherein: W is the water content in the sample solution, in μg; Q represents the amount of electricity consumed by the electrolytic electrode to electrolyze water in the sample solution, expressed in mC. 18 is the molecular weight of water; 96485 is the number of millicoulombs of electricity required to electrolyze 1 millimole of water; S9: Drainage: When the total weight of Karl Fischer reagent and sample liquid in the electrolysis tank reaches the set upper limit, the reagent pump is started in reverse. The feed three-way solenoid valve and the quantitative three-way solenoid valve are connected to the detector flow channel and the reagent pump flow channel, respectively. The third intermediate flow channel is connected to the fourth intermediate flow channel, the fifth intermediate flow channel and the waste liquid discharge channel in sequence. The feed three-way solenoid valve and the quantitative three-way solenoid valve are opened. All the mixed liquid in the electrolysis tank is discharged into the waste liquid pool in sequence through the detector flow channel, the first intermediate flow channel, the spiral pipe, the second intermediate flow channel, the reagent pump flow channel, the reagent pump, the third intermediate flow channel, the fourth intermediate flow channel, the fifth intermediate flow channel and the waste liquid discharge channel. S10: Anhydrous ethanol cleaning: Start the reagent pump to rotate forward. The feed three-way solenoid valve is connected to the detector flow channel. The detector flow channel is connected in sequence to the first intermediate flow channel, the spiral pipe, the second intermediate flow channel, the reagent pump flow channel, and the reagent pump. One end of the third intermediate flow channel is connected to the reagent pump, and the other end is connected to the ethanol flow channel through the ethanol feed three-way solenoid valve. Open the feed three-way solenoid valve, the metering three-way solenoid valve, and the ethanol feed three-way solenoid valve to allow anhydrous ethanol to enter the electrolysis tank and clean the electrolysis tank. The waste liquid after cleaning is discharged according to step S9. The cleaning is completed after the liquid is discharged.

[0015] Compared with existing related technologies, the beneficial effects of the present invention are as follows: (1) An overall structure with an electrical control box and an analysis cabinet set up in an explosion-proof cabinet is adopted. An electrolytic detection device and a photometric detector are designed in the analysis cabinet. The automatic detection of trace moisture in liquids containing different concentrations of water is carried out by the Karl Fischer coulometric method and photometric method through the PLC control system. The detection and analysis of dual detection modes are realized. It has comprehensive functions, wide applicability, short detection time and high efficiency. In addition, a positive pressure control system is set up to keep the explosion-proof cabinet in a nitrogen positive pressure environment. Not only is the overall structure compact and safe, but it also effectively reduces the moisture entering the analysis components and improves the detection accuracy.

[0016] (2) The liquid inlet device adopts a manifold valve plate assembly consisting of a PTFE gasket, a stainless steel connector, a stainless steel valve seat, and four three-way solenoid valves. A PTFE gasket is installed between the stainless steel connector and the stainless steel valve seat. Through the optimized design of various shaped flow grooves in the PTFE gasket, the through holes in the stainless steel connector, and the interface through holes in the stainless steel valve seat, the length, width, and thickness of the PTFE gasket, stainless steel connector, and stainless steel valve seat are fully utilized, making it extremely convenient to complete the pipeline connection with the feed pump, sampling valve, reagent pump, electrolytic detection device, etc., forming multiple sealed lines. The liquid channel, while pretreating reagents and sample solutions, effectively realizes multiple functions such as quantification, feeding, discharging, and ethanol cleaning of Karl Fischer reagents and sample solutions. Its compact structure, small footprint, convenient installation and operation, reliable operation, high efficiency, and accurate quantification improve the precision and efficiency of detection. It also fully utilizes the corrosion resistance, high strength, and non-deformation properties of stainless steel connectors and valve seats, as well as the corrosion resistance, sealing, and ease of processing of PTFE gaskets, ensuring leak-proof operation, reducing failure rate, extending service life, and lowering the manufacturing cost of the analyzer.

[0017] (3) The through holes, air inlet channels, and waste liquid discharge channels on the stainless steel connector seat adopt a combination of smooth sections and threaded sections, which makes it easy to quickly connect to feed pumps, reagent pumps, reagent bottles, electrolytic detection devices, second gas dehydrators, waste liquid pools, spiral pipeline quantitative tubes, etc. through pipelines. The operation is convenient, the sealing is good, and the convenience and efficiency of installation, maintenance and operation are greatly improved.

[0018] (4) The design of the second gas dehydrator, which is connected to both the manifold valve plate assembly and the electrolytic photometric detection device, can not only remove moisture from the gas that pushes the reagents and sample solutions into the electrolytic tank, but also remove moisture from the gas in the electrolytic tank at all times, ensuring that the reagents and sample solutions are free from dissolved moisture in the gas in the pipeline and the electrolytic tank. The first gas dehydrator, which is connected to the Karl Fischer reagent bottle and the ethanol reagent bottle, removes moisture from the gas in the two reagent bottles, and can strictly control the moisture content when adding Karl Fischer and ethanol to the liquid inlet device and the electrolytic tank to meet the specified requirements, so that the entire detection process is not affected by the introduction of external moisture and the accuracy of the detection results is improved.

[0019] (5) The electrolytic tank is designed with a manual liquid filling port and a manual liquid filling port plug, which can be used to manually add materials in extreme cases such as blockage of the liquid inlet pipe, so that the testing process can be carried out smoothly.

[0020] (6) An air vent and liquid inlet / outlet are provided at the top of the electrolysis tank, and electrolysis electrodes and potential electrodes are inserted. This makes full use of the volume of the electrolysis tank and provides the conditions for measuring moisture content by Karl Fischer coulometric method. This not only reduces the space occupied by the equipment, but also improves the operating efficiency as much as possible.

[0021] (7) By adopting a detector housing with an irregular structure, the light source emission module and light receiving module of the photometric detector for detecting moisture content, the electrolytic tank of Karl Fischer coulometric method, potential electrode, electrolytic electrode, weighing sensor and stirring module necessary for the detection process were compactly set up. By centrally connecting the terminals, the equipment layout was made more reasonable and compact. At the same time, it was realized that the moisture content of different ranges could be accurately detected online using both photometric and Karl Fischer coulometric methods. This provided the necessary data for real-time production, ensured the smooth progress of production, improved product quality and reduced production costs.

[0022] (8) The stir bar in the electrolysis tank and the stirring motor in the base constitute a high-efficiency stirring module, which realizes real-time stirring of the sample liquid in the electrolysis tank, and improves the efficiency of detection and the accuracy of results.

[0023] (9) Using a spiral tube as the quantitative tube allows for easy replacement of spiral tubes of different lengths according to the detection requirements, in order to meet the quantitative needs of different scenarios, improve the accuracy of quantitative measurement, and expand the applicability of the analyzer.

[0024] (10) The mounting ring, the annular vertical rack on the mounting ring, the gears on the output end of the drive motors of the light source emitting module and the light receiving module that mesh with the annular vertical rack on the mounting ring, and the two mounting ring lifting cylinders symmetrically installed below the mounting ring enable the light source emitting module and the light receiving module to emit and receive light in different directions and at different heights in the electrolysis tank, avoiding measurement errors caused by uneven mixing of the mixed liquid in the electrolysis tank or contamination of the electrolysis tank wall, and also expanding the applicability of the analyzer. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the overall structure of an online trace moisture analyzer based on dual detection modes according to the present invention. Figure 2 for Figure 1 The right view; Figure 3 for Figure 1 Schematic diagram of the electrolytic photometric detection device; Figure 4 for Figure 3 Exploded view of the electrolysis detection device; Figure 5 for Figure 3 Exploded view of the mesophotometer detector; Figure 6 for Figure 5 Structural diagram of the detector housing; Figure 7 for Figure 6 A bottom view; Figure 8 for Figure 1 Structural diagram of the central manifold valve plate assembly; Figure 9 for Figure 8 Exploded view; Figure 10 for Figure 9 Front view of the PTFE sealing gasket; Figure 11 for Figure 1 A connection diagram of the liquid inlet device in its default state; Figure 12 for Figure 9 A three-dimensional view of the stainless steel connector from the front and above. Figure 13 for Figure 9 A three-dimensional view of the stainless steel connector from the rear and lower part of the body; Figure 14 for Figure 9 A perspective view of the stainless steel valve seat from the side connected to the PTFE gasket. Figure 15 for Figure 9 A perspective view of a stainless steel valve seat viewed from the side where a three-way solenoid valve is installed. Figure 16 An exploded view of a photometric detector with a mounting ring installed. Figure 17 for Figure 16 Top view; Figure 18 This is a control framework diagram of an online trace moisture analyzer based on dual detection modes according to the present invention.

[0026] Figure 1-18The components include: 1. Explosion-proof cabinet; 2. Electrical control box; 21. PLC controller; 22. Switching power supply; 23. Touch screen; 24. Explosion-proof wiring port; 25. Power switch; 3. Analysis cabinet; 4. Analysis components; 5. Reagent supply components; 51. Karl Fischer reagent bottle; 52. Ethanol reagent bottle; 53. First gas dehydrator; 6. Detection components; 61. Electrolytic photometric detection device; 611. Electrolytic detection device; 6111. Electrolytic vessel; 6111. Potential electrode; 6112. Electrolytic electrode; 6113. Magnetic stir bar; 6114. Exhaust port; 6115. Liquid inlet / outlet; 6116. Manual liquid filling port; 6117. Manual liquid filling port plug; 6118. Photometric detector. 12. Detector housing 6121, light source emitting template 61211, light receiving module 61212, terminal block 61213, mounting slot 61214, mounting ring 61215, mounting ring lifting cylinder 61216, base 6122, tray 61221, stirring motor 61222, weighing sensor 61223, base plate 61224, liquid inlet device 62, manifold valve plate assembly 621, stainless steel connector seat 6211, feed through hole 621101, detector through hole 621102, reagent pump first through hole 621103, recovery through hole 621104, reagent pump second through hole 62 1105, Quantitative tube connection first through hole 621106, quantitative tube connection second through hole 621107, ethanol through hole 621108, Karl Fischer through hole 621109, waste liquid discharge channel 621110, air inlet channel 621111, PTFE sealing gasket 6212, feed pump channel 621201, detector channel 621202, recovery channel 621203, reagent pump channel 621204, ethanol channel 621205, Karl Fischer channel 621206, first intermediate channel 621207, second intermediate channel 621208, third intermediate channel 62 1209, Fourth intermediate flow channel 621210, Fifth intermediate flow channel 621211, Spiral pipe 621212, Stainless steel valve seat 6213, Feed three-way solenoid valve 62131, Quantitative three-way solenoid valve 62132, Ethanol feed three-way solenoid valve 62133, Karl Fischer feed three-way solenoid valve 62134, Feed pump 622, Reagent pump 623, Second gas dehydrator 63, Sampling assembly 7, Sampling valve 71, Pneumatic solenoid valve 72, Sampling pressure reducing valve 73, Positive pressure control system 8, Positive pressure controller 81, Positive pressure control solenoid valve 82, Positive pressure control pressure reducing valve 83, Flow regulating valve 84. Detailed Implementation

[0027] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention, but the embodiments are not intended to limit the present invention. Example

[0028] like Figure 1-15As shown, an online trace moisture analyzer based on dual detection modes includes an explosion-proof cabinet 1 and a PLC control system. The explosion-proof cabinet 1 includes an analysis cabinet 3 located at the bottom of the explosion-proof cabinet 1 and an electrical control box 2 located above the analysis cabinet 3. The structure of setting the analysis cabinet 3 and the electrical control box 2 as an integrated explosion-proof cabinet not only ensures the safety of the analyzer operation, but also improves the structural compactness of the analyzer.

[0029] The PLC control system includes a PLC controller 21, a touch screen 23, and supporting software. The PLC controller 21 is installed inside the electrical control box 2, and the touch screen 23 is installed on the front door of the electrical control box 2. The electrical control box 2 also contains a switching power supply 22, a power switch 25, and internal wiring components. The PLC controller 21 is connected to the internal wiring components via wires. An explosion-proof wiring port 24 is provided on one outer wall of the electrical control box 2. The internal wiring components of the electrical control box 2 are connected to external power supplies and other signal devices via wires through the explosion-proof wiring port 24. This ensures the safety of the wiring and makes the analyzer wiring more orderly and aesthetically pleasing.

[0030] The analysis cabinet 3 is equipped with an analysis component 4, which includes a reagent supply component 5 located at the bottom of the analysis cabinet 3 and a detection component 6 located at the top of the analysis cabinet 3 and connected to the reagent supply component 5 via a pipeline.

[0031] The reagent supply assembly 5 includes a Karl Fischer reagent bottle 51 containing Karl Fischer reagent, an ethanol reagent bottle 52 containing anhydrous ethanol, and a first gas dehydrator 53 connected to the Karl Fischer reagent bottle 51 and the ethanol reagent bottle 52 via pipelines. The Karl Fischer reagent bottle 51 and the ethanol reagent bottle 52 can supply Karl Fischer reagent and anhydrous ethanol to the detection assembly 6, respectively. The first gas dehydrator 53 is used to remove water and dry the gas in the Karl Fischer reagent bottle 51 and the ethanol reagent bottle 52 in real time, so that the reagents in the Karl Fischer reagent bottle 51 and the ethanol reagent bottle 52 avoid absorbing moisture from the gas as much as possible, and ensure that the detection results are not affected by moisture and other impurities introduced by the addition of reagents.

[0032] The detection assembly 6 includes an electrolytic photometric detection device 61 disposed above the reagent supply assembly 5, and a liquid inlet device 62 fixed inside the analysis cabinet 3, connected to the electrolytic photometric detection device 61 via a pipeline, which pre-treats the sample solution, quantifies the volume of the sample solution and reagents, injects the sample solution and reagents into the electrolytic photometric detection device 61, and can discharge the liquid in the electrolytic photometric detection device 61. A second gas dehydrator 63 is also fixedly installed above the electrolytic photometric detection device 61 inside the analysis cabinet 3. The electrolytic photometric detection device 61 and the liquid inlet device 62 are respectively connected to the second gas dehydrator 63 via pipelines. A gas dehydrator 63 is connected to the electrolytic photometric detection device 61, the liquid inlet device 62, and the pipeline connecting the electrolytic photometric detection device 61 and the liquid inlet device 62. The second gas dehydrator 63 is used to remove water and dry the gas in real time, so that the gas entering the electrolytic photometric detection device 61 and the liquid inlet device 62 is as free of moisture as possible. It can also dry and remove water from the electrolytic photometric detection device 61 at all times, and prevent the sample liquid and reagents in the electrolytic photometric detection device 61 from being seeped in by external moisture as much as possible, thereby improving the accuracy of the detection results and ensuring the smooth progress of the detection and analysis process.

[0033] The electrolytic photometric detection device 61 includes an electrolytic detection device 611 for containing reagents and sample solutions, having reagent and sample solution inlet and outlet interfaces; a photometric detector 612 disposed below the electrolytic detection device 611; and a stirring module for stirring the reagents and sample solutions in the electrolytic detection device 611. The electrolytic detection device 611 includes an electrolytic vessel 6111, which can contain sample solutions and reagents. An electrolytic electrode 6113 and a potential electrode 6112 are inserted into the top of the electrolytic vessel 6111. The potential electrode 6112 is always in operation and can perform real-time potential detection of the reagents and sample solutions in the electrolytic vessel 6111. The electrolytic electrode 6113 can electrolyze the water in the reagents and sample solutions in the electrolytic vessel 6111. The top of the electrolysis tank 6111 is also provided with an vent 6115 and an inlet / outlet 6116 for injecting and discharging reagents and sample solutions. The vent 6115 is connected to the second gas dehydrator 63 through a pipeline, which can ensure the smooth inlet and outlet of the liquid in the electrolysis tank 6111 under balanced pressure, and can also dry and remove water from the gas in the electrolysis tank 6111 in real time. A magnetic stir bar 6114 is provided inside the electrolysis tank 6111. A manual liquid filling port 6117 is also provided on one side wall of the electrolysis tank 6111. A manual liquid filling port plug 6118 is provided on the manual liquid filling port 6117. The structure of the electrolysis tank 6111 compactly arranges the vent 6115, the inlet / outlet 6116, the electrolysis electrode 6113 and the potential electrode 6112, which not only reduces the space occupied by the equipment, but also maximizes the efficiency of detection and analysis.The photometric detector 612 includes a detector housing 6121 for housing the electrolysis detection device 611 and a base 6122 disposed inside the lower part of the detector housing 6121. The detector housing 6121 is a hollow shell and is fixed to the analysis cabinet 3. A light source emitting module 61211 and a light receiving module 61212 are symmetrically installed on the lower side wall inside the detector housing 6121. A terminal block 61213 is provided on one outer wall of the detector housing 6121. The shell wall of the detector housing 6121 has an irregular shape, and the upper shell wall is provided with a manual liquid filling port 61 for the electrolysis vessel 6111. The detector housing 6121 has a mounting slot 61214. A base plate 61224 is fixed to the bottom of the detector housing 6121. The base 6122 is fixedly mounted on the base plate 61224. The upper part of the base 6122 is a tray 61221 for placing the electrolytic detection device 611. A stirring motor 61222 with a magnet installed at its output end is installed inside the lower part of the base 6122. A weighing sensor 61223 is installed at the bottom of the base 6122. The light source emitting module 61211 and the light receiving module 61212 are positioned higher than the tray 61221, allowing light to pass through the lower middle part of the electrolytic tank 6111, i.e., the middle position of the sample liquid and reagent liquid levels. Inside the electrolytic tank 6111... The magnetic stir bar 6114 and the stirring motor 61222, whose output end is equipped with a magnet and is installed inside the lower part of the base 6122, constitute a stirring module for stirring the reagents and sample solutions in the electrolysis detection device 611. The rotation of the stirring motor 61222 can drive the magnetic stir bar 6114 inside the electrolysis tank 6111 to rotate through magnetic force, thereby stirring the liquid in the electrolysis tank 6111. Through the structural design of the detector housing 6121, the base 6122 adopts a hollow inverted truncated cone structure with a disc on the upper part and a stirring motor 61222 and a weighing sensor 61223 installed on the lower part, which makes the electrolysis detection device 611 stable and compact. The device is compactly arranged, simultaneously housing the potential electrode 6112, electrolysis electrode 6113, light source emitting module 61211 of the photometric detector 612, light receiving module 61212, weighing sensor 61223, and stirring motor 61222. This allows the electrolytic photometric detection device 61 to simultaneously perform photometric detection and Karl Fischer coulometric detection of trace moisture content. This enables rapid detection of sample solutions containing different concentrations of trace moisture using different detection methods, resulting in smaller deviations in detection results and higher accuracy and efficiency. Furthermore, the stirring module continuously and uniformly stirs the liquid within the electrolysis tank 6111, further improving the accuracy and efficiency of the detection.

[0034] The electrolytic electrode 6113, potential electrode 6112, light source emitting module 61211 and light receiving module 61212, stirring motor 61222, weighing sensor 61223 and terminal block 61213 are connected by wires, and are connected to PLC controller 21 in electrical control box 2 through terminal block 61213 and wires.

[0035] The liquid inlet device 62 includes a manifold valve plate assembly 621 fixed on the analysis cabinet 3, and a reagent pump 623 and a feed pump 622 connected to the manifold valve plate assembly 621 through pipelines. The reagent pump 623 and the feed pump 622 are fixed inside the analysis cabinet 3 and connected to the PLC controller 21 through wires.

[0036] Specifically, the reagent pump 623 is a peristaltic pump, and the feed pump 622 can be a peristaltic pump or any other pump that can meet the feeding requirements and the requirements of the site environment.

[0037] The analysis cabinet 3 is also equipped with a sampling component 7 connected to the analysis component 4 via a pipeline. The sampling component 7 includes a sampling valve 71 located on one side of the outer wall of the analysis cabinet 3 and connected to the liquid inlet device 62 of the analysis component 4 via a pipeline; a pneumatic solenoid valve 72 connected to the control end of the sampling valve 71 via a pipeline and controlling the opening and closing of the sampling valve 71; and a sampling pressure reducing valve 73 connected to the other end of the pneumatic solenoid valve 72 to control the airflow pressure or flow rate of the pneumatic solenoid valve 72. The other end of the sampling pressure reducing valve 73 is connected to compressed gas. Specifically, the control end of the sampling valve 71 is a pneumatic switch valve, and the pneumatic solenoid valve 72 is connected to a PLC controller via a wire. The pneumatic solenoid valve 72 is controlled by the PLC controller. The gas passing through the pneumatic switch valve at the control end of the sampling valve 71 can be dry air or nitrogen, and the pressure is generally not less than 0.4 MPa.

[0038] The outlet of the sampling valve 71 is connected to the input end of the feed pump 622 via a pipeline. Both ends of the sampling valve 71 are connected to the production pipeline via pipelines. Under normal circumstances, the sampling valve 71 is in the closed state. When sampling is required, the sampling valve 71 is opened, and the sample liquid is allowed to circulate in the sampling valve 71 and the inlet and outlet pipelines connected thereto for a period of time to ensure that the sample liquid is consistent with the real-time liquid composition in the production process. Then the feed pump 622 is started to take samples.

[0039] The pneumatic solenoid valve 72 and the sampling pressure reducing valve 73 are located in the lower part of the analysis cabinet 3.

[0040] The manifold valve plate assembly 621 includes a stainless steel connector seat 6211, a stainless steel valve seat 6213, and a PTFE sealing gasket 6212 with several through-flow grooves fixed between the stainless steel connector seat 6211 and the stainless steel valve seat 6213. A feed three-way solenoid valve 62131, a metering three-way solenoid valve 62132, an ethanol feed three-way solenoid valve 62133, and a Karl Fischer feed three-way solenoid valve 62134 are fixedly installed on the stainless steel valve seat 6213. 34 is connected to the PLC controller 21 via wires. The stainless steel connector 6211, PTFE gasket 6212, and stainless steel valve seat 6213 are fixed together by screws. The connector and valve seat are made of stainless steel, which has the advantages of corrosion resistance, high strength, non-deformation, easy surface processing, and flatness. The gasket is made of polytetrafluoroethylene, which has the advantages of corrosion resistance, high sealing performance, and easy processing. The PTFE gasket 6212 is pressed and fixed between the stainless steel connector 6211 and the stainless steel valve seat 6213 by screws, which fully ensures that the device does not leak, reduces the failure rate, extends the service life, and reduces the manufacturing cost of the analyzer.

[0041] The stainless steel valve seat 6213 has three interface through holes that communicate with the interfaces of the feed three-way solenoid valve 62131, the metering three-way solenoid valve 62132, the ethanol feed three-way solenoid valve 62133, and the Karl Fischer feed three-way solenoid valve 62134.

[0042] The stainless steel connector seat 6211 has a feed through hole 621101, a detector through hole 621102, a reagent pump first through hole 621103, a recovery through hole 621104, a reagent pump second through hole 621105, a quantitative tube connection first through hole 621106, a quantitative tube connection second through hole 621107, an ethanol through hole 621108, and a Karl Fischer through hole 621109.

[0043] The through-flow channels on the PTFE sealing gasket 6212 include a feed pump channel 621201, a detector channel 621202, a recovery channel 621203, a reagent pump channel 621204, an ethanol channel 621205, a Karl Fischer channel 621206, and a first intermediate channel 621207, a second intermediate channel 621208, a third intermediate channel 621209, a fourth intermediate channel 621210, and a fifth intermediate channel 621211. The feed pump channel 621201 and the detector channel 621202... The recovery channel 621203, reagent pump channel 621204, ethanol channel 621205, Karl Fischer channel 621206, and the first intermediate channel 621207, second intermediate channel 621208, third intermediate channel 621209, fourth intermediate channel 621210, and fifth intermediate channel 621211 are through channels extending through the thickness of the PTFE gasket 6212. The feed pump channel 621201 and the detector channel 621202 are integrally located on opposite sides of the same end of the first intermediate channel 621207. Each has one end adjacent to the end of the first intermediate flow channel 621207. The recovery flow channel 621203 and the reagent pump flow channel 621204 are integrally disposed on both sides of the same end of the second intermediate flow channel 621208, and each has one end adjacent to that end of the second intermediate flow channel 621208. The detector flow channel 621202, the reagent pump flow channel 621204, the ethanol flow channel 621205, and the Karl Fischer flow channel 621206 are disposed on one side of the same long side of the PTFE sealing gasket 6212. The detector flow channel 621202 and the reagent pump flow channel 621204 are disposed on the same side of the PTFE sealing gasket 6212. The flow channels 621204 are adjacent to each other and arranged sequentially from the outside to the inside along the length of the PTFE gasket 6212, starting from the position closest to one side of the wide edge. To optimize the layout of the components, facilitate processing and pipeline connection with other components, and also improve aesthetics, the PTFE gasket 6212 adopts a cuboid sheet structure. The center lines of the feed pump flow channel 621201 and the detector flow channel 621202 are collinear, and the center lines of the recovery flow channel 621203 and the reagent pump flow channel 621204 are collinear. Both sets of center lines are respectively arranged along the width direction of the PTFE gasket 6212.

[0044] The adjacent ends of the feed pump channel 621201, the detector channel 621202, and the first intermediate channel 621207 are respectively connected to the three ports of the feed three-way solenoid valve 62131 through corresponding interface through holes on the stainless steel valve seat 6213. The other end of the feed pump channel 621201 is connected to the feed pump 622 through the feed through hole 621101 via a pipeline. The other end of the detector channel 621202 is connected to the inlet and outlet ports 6116 of the electrolysis tank 6111 of the electrolysis detection device 611 through the detector through hole 621102 via a pipeline. The recovery channel 621203, the reagent pump channel 621204, and the second intermediate channel 621207 are connected to the feed pump channel 621207. One end of the flow channel 621208 is connected to the three ports of the quantitative three-way solenoid valve 62132 via corresponding interface through holes on the stainless steel valve seat 6213. The other end of the recovery flow channel 621203 is connected to an externally installed recovery tank via a pipeline through a recovery through hole 621104. The other end of the reagent pump flow channel 621204 is connected to the output end of the reagent pump 623 via a pipeline through the first reagent pump through hole 621103. One end of the third intermediate flow channel 621209 is adjacent to one end of the ethanol flow channel 621205 and one end of the fourth intermediate flow channel 621210, and is connected to the ethanol feed three-way solenoid valve 62132 via corresponding interface through holes on the stainless steel valve seat 6213. The three ports of the solenoid valve 62133 are connected. The other end of the third intermediate flow channel 621209 is connected to the input end of the reagent pump 623 via a pipeline through the second through-hole 621105 of the reagent pump. The other end of the ethanol flow channel 621205 is connected to the ethanol reagent bottle 52 via a pipeline through the ethanol through-hole 621108. The other end of the fourth intermediate flow channel 621210, one end of the Karl Fischer flow channel 621206, and one end of the fifth intermediate flow channel 621211 are adjacent and connected to the three ports of the Karl Fischer feed three-way solenoid valve 62134 via corresponding interface through-holes on the stainless steel valve seat 6213. The Karl Fischer flow channel 621206... The other end is connected to the Karl Fischer reagent bottle 51 through a pipeline via a Karl Fischer through-hole 621109; the other end of the first intermediate flow channel 621207, which is not adjacent to the feed pump flow channel 621201 and the detector flow channel 621202, is connected to the first through-hole 621106 of the quantitative tube; the other end of the second intermediate flow channel 621208, which is not adjacent to the recovery flow channel 621203 and the reagent pump flow channel 621204, is connected to the second through-hole 621107 of the quantitative tube; a spiral pipe 621212 is provided between the first through-hole 621106 of the quantitative tube and the second through-hole 621107 of the quantitative tube, and the two are connected by the spiral pipe 621212.

[0045] The two sides of the long side of the stainless steel connector 6211 are respectively provided with an air inlet channel 621111 and a waste liquid discharge channel 621110, which are connected to the two ends of the fifth intermediate flow channel 621211. The air inlet channel 621111 and the through hole 621102 of the through detector are located on the same half side of the stainless steel connector 62111, and the inlet of the air inlet channel 621111 is opened on the long side adjacent to the through surface of the through hole 621102 of the through detector, and is connected to the second gas dehydrator 63 through a pipeline. The outlet of the air inlet channel 621111 is opened on the stainless steel connector 6211 and is connected to the second gas dehydrator 63 through a pipeline. The PTFE gasket 6212 is in contact with the other end of the fifth intermediate flow channel 621211. The waste liquid discharge channel 621110 and the feed through hole 621101 are located on the same half of the stainless steel connector seat 6211. The inlet of the waste liquid discharge channel 621110 is opened on the surface of the stainless steel connector seat 6211 that is in contact with the PTFE gasket 6212 and is connected to one end of the fifth intermediate flow channel 621211. The outlet of the waste liquid discharge channel 621110 is opened on the long side opposite to the inlet of the air inlet channel 621111 and is connected to the waste liquid pool through a pipeline.

[0046] Specifically, the feed through-hole 621101, detector through-hole 621102, reagent pump first through-hole 621103, recovery through-hole 621104, reagent pump second through-hole 621105, metering tube connection first through-hole 621106, metering tube connection second through-hole 621107, ethanol through-hole 621108, and Karl Fischer through-hole 621109 are each composed of a smooth through-hole section and a through-hole section with internal threads connected to the smooth through-hole section. The smooth through-hole section is located on the side that is in contact with the PTFE sealing gasket 6212, and is connected to the feed pump flow channel 621201, detector flow channel 621202, reagent pump flow channel 621204, recovery flow channel 621203, third intermediate flow channel 621209, and first intermediate flow channel 621209, respectively. 1207, the second intermediate flow channel 621208, the ethanol flow channel 621205, and the Karl Fischer flow channel 621206 are connected. The threaded through-hole section is located on the side away from the PTFE gasket 6212 and is connected to the feed pump 622, the electrolytic photometric detection device 61, the output end of the reagent pump 623, the recovery tank, the input end of the reagent pump 623, both ends of the spiral pipe 621212, the ethanol reagent bottle 52, and the Karl Fischer reagent bottle 51 through pipelines. The smooth through-hole section and the threaded through-hole section are sealed together. The inner diameter of the threaded through-hole section is larger than that of the smooth through-hole section. The threaded through-hole section greatly facilitates the connection with external pipelines, ensures the sealing of the connection, and also makes the volume more compact and the appearance more beautiful.

[0047] Specifically, both the air intake channel 621111 and the waste liquid discharge channel 621110 are composed of an L-shaped smooth inner hole section directly connected to the fifth intermediate flow channel 621211 and an internally threaded hole section connected to the L-shaped smooth inner hole section. The internally threaded hole section of the air intake channel 621111 is connected to the second gas dehydrator 63 through a pipeline, and the internally threaded hole section of the waste liquid discharge channel 621110 is connected to the waste liquid pool through a pipeline. The L-shaped smooth inner hole section and the internally threaded hole section of the air intake channel 621111 and the waste liquid discharge channel 621110 are sealed together, and the inner diameter of the internally threaded hole section is larger than the inner diameter of the L-shaped smooth inner hole section.

[0048] The feed three-way solenoid valve 62131 and the metering three-way solenoid valve 62132 are kept open and closed simultaneously. Specifically, the feed three-way solenoid valve 62131 is synchronized with the feed pump 622, and the metering three-way solenoid valve 62132 is synchronized with the externally installed recovery tank. The feed three-way solenoid valve 62131 is synchronized with the electrolytic photometric detection device 61, and the metering three-way solenoid valve 62132 is synchronized with the reagent pump 623. That is, if the feed three-way solenoid valve 62131 is connected to the feed pump 622 through the feed pump flow channel 621201 and the feed through hole 621101, it is synchronized with the feed pump 622. When the electrolytic photometric detection device 61 is disconnected, the quantitative three-way solenoid valve 62132 is also connected to the externally installed recovery pool through the recovery trough 621203 and the recovery through hole 621104, and disconnected from the reagent pump 623. If the feed three-way solenoid valve 62131 is disconnected from the feed pump 622, and connected to the electrolytic photometric detection device 61 through the detector trough 621202 and the detector through hole 621102, the quantitative three-way solenoid valve 62132 is also disconnected from the recovery pool, and connected to the reagent pump 623 through the reagent pump trough 621204 and the reagent pump first through hole 621103.

[0049] Of course, to improve efficiency and for aesthetic purposes, the feed through-hole 621101, detector through-hole 621102, reagent pump first through-hole 621103, recovery through-hole 621104, reagent pump second through-hole 621105, quantitative tube connection first through-hole 621106, quantitative tube connection second through-hole 621107, ethanol through-hole 621108, Karl Fischer through-hole 621109, air inlet channel 621111, and waste liquid discharge channel 621110, as well as the interface through-hole on the stainless steel valve seat 6213, can be set to be perpendicular to the corresponding surface; the shape of the flow channel can also be adapted to specific requirements.

[0050] By utilizing the through-flow groove on the PTFE sealing gasket 6212 of the manifold valve plate assembly 621, the through hole of the stainless steel connector seat 6211, the interface through hole on the stainless steel valve seat 6213, and the four three-way solenoid valves, the length, width, and thickness of the aforementioned components are fully utilized. Combined with the feed pump 622, reagent pump 623, and sampling valve 71, multiple different and sealed liquid channels are formed. The system can switch between adding reagents, sample solutions, draining liquids, and adding anhydrous ethanol for cleaning at any time according to process requirements. Furthermore, the spiral pipe 621212 can be replaced with different lengths at any time according to process requirements to meet the volume quantification requirements of different scenarios. This system realizes multiple functions such as precise quantification of Karl Fischer reagents and sample solutions, feeding, draining liquids, and ethanol cleaning. The system has a compact structure, occupies little space, is easy to install and operate, is reliable, and has high efficiency, which greatly improves the accuracy and efficiency of detection. At the same time, the manufacturing cost is low, reducing the production and maintenance costs of the analyzer.

[0051] On the other side of the analysis cabinet 3, a positive pressure control system 8 is also installed. The positive pressure control system 8 includes a positive pressure controller 81 installed on the other side of the analysis cabinet, a positive pressure control solenoid valve 82 connected to the positive pressure controller 81 and controlled by the positive pressure controller 81 to open and close, a positive pressure control pressure reducing valve 83 connected to one end of the positive pressure control solenoid valve 82, a flow regulating valve 84 provided on the positive pressure control solenoid valve 82, the other end outlet of the flow regulating valve 84 is located inside the explosion-proof cabinet 1, and the other end of the positive pressure control pressure reducing valve 83 is connected to compressed gas, specifically, nitrogen gas. The positive pressure controller 81 and the positive pressure control solenoid valve 82 are connected to the box wiring assembly inside the electrical control box 2 through wires.

[0052] The positive pressure control system 8 also includes a pressure sensor installed inside the analysis cabinet 3. During operation, the positive pressure controller 81 detects the gas pressure inside the explosion-proof cabinet 1 in real time through the pressure sensor. The pressure sensor transmits the pressure inside the explosion-proof cabinet 1 to the positive pressure controller 81 in real time and automatically adjusts the opening and closing of the positive pressure control solenoid valve 82 and the positive pressure control pressure reducing valve 83 to ensure that the pressure inside the explosion-proof cabinet 1 is always at the pressure required for operation. When the positive pressure control solenoid valve 82 is opened, the gas, after being reduced in pressure by the positive pressure control pressure reducing valve 83, enters from one end of the positive pressure control solenoid valve 82, and the flow rate is adjusted by the flow regulating valve 84 before entering the explosion-proof cabinet 1. The flow regulating valve 84 can be manually adjusted to ensure that the explosion-proof cabinet 1 is in a positive pressure state, ensuring the safe operation of the explosion-proof cabinet 1, and preventing corrosion and damage to the components inside the explosion-proof cabinet 1. When the pressure is insufficient, the positive pressure control system 8 sends a signal to the PLC control system, and the power supply to each part of the PLC control system is automatically cut off, stopping operation. Therefore, as long as the analyzer is in operation, the explosion-proof cabinet 1 always maintains the nitrogen positive pressure environment required by the process. Consequently, the gases in the Karl Fischer reagent bottle 51, the ethanol reagent bottle 52, the gases entering the manifold valve plate assembly 621 through the second gas dehydrator 63, and the gases above the liquid in the electrolysis tank 6111 are all positive pressure nitrogen. This not only effectively prevents flammable and explosive gases and dust from the external environment from seeping into the cabinet, cutting off the combustible conditions of the three elements of explosion at the source, reducing the oxygen concentration in the cabinet and avoiding explosion, but also minimizes the possibility of Karl Fischer reagents and sample liquids absorbing water vapor, improving the accuracy of detection. At the same time, it also reduces analyzer failures, improves the efficiency of detection and analysis, and reduces costs.

[0053] like Figure 16-17As shown, to further improve the detection accuracy of the analyzer and expand its application range, a mounting ring 61215 is installed on the lower inner side wall of the detector housing 6121. The light source emitting module 61211 and the light receiving module 61212 are mounted on the lower inner side wall of the detector housing 6121 via the mounting ring 61215. An annular vertical rack is provided on the upper inner section of the mounting ring 61215. The light source emitting module 61211 and the light receiving module 61212 are mounted on the mounting ring 61215. On the upper surface of 215, drive motors are respectively installed on the light source emitting module 61211 and the light receiving module 61212. A gear is installed on the output end of the drive motor that meshes with the annular vertical rack on the upper inner side of the mounting ring 61215. Two mounting ring lifting cylinders 61216 are symmetrically installed below the mounting ring 61215. The mounting ring lifting cylinders 61216 are integrally mounted on the inner side wall of the lower part of the detector housing 6121. The output end of the mounting ring lifting cylinder 61216 is connected to the mounting ring 61215. The lower end face of mounting ring 61215 is connected, and through the cooperation of gears and a ring-shaped vertical rack and PLC control system, the light source emitting module 61211 and the light receiving module 61212 can be controlled to move synchronously along the circumferential direction of the upper end face of mounting ring 61215. This allows the light source emitting module 61211 and the light receiving module 61212 to collect light values ​​from different directions on the same horizontal plane of electrolysis tank 6111. This can eliminate measurement errors caused by insufficient and uneven mixing of the mixed liquid and the adhesion of residues on the wall of electrolysis tank 6111. The two mounting ring lifting cylinders 61216 connected to the lower end face of mounting ring 61215 are controlled by the PLC control system to lift synchronously, enabling the light source emitting module 61211 and the light receiving module 61212 to move up and down synchronously. This allows the light to collect light values ​​at different heights relative to electrolysis tank 6111. This can reduce measurement errors caused by the composition deviation of the mixed liquid at different heights and make the analyzer adaptable to various scenarios with different sampling quality requirements, further expanding the applicability of the analyzer. Of course, the mounting ring lifting cylinder 61216 can also be mounted on the base plate 61224, and its output end passes through the gap between the tray 61221 and the inner side wall of the detector housing 6121 and connects to the lower end face of the mounting ring 61215.

[0054] The control framework diagram of each part of the online trace moisture analyzer based on dual detection mode is as follows: Figure 18 As shown, during operation, the pressure sensor transmits the pressure inside the explosion-proof cabinet 1 to the positive pressure controller 81 in real time. The positive pressure controller 81 controls the opening of the positive pressure control solenoid valve 82 and the positive pressure control pressure reducing valve 83 according to the pressure situation to ensure that the pressure of the explosion-proof cabinet 1 is always at the pressure required for operation. When the pressure of the explosion-proof cabinet 1 does not meet the requirements, the positive pressure control system 8 will send a signal to the PLC control system, and the power supply to each part of the PLC control system will be automatically cut off, stopping the operation.

[0055] Both the touchscreen 23 and the PLC controller 21 run corresponding supporting software. The PLC controller 21 runs the pre-downloaded supporting control program to complete real-time data acquisition and logical operation processing. Through data interaction with the supporting software of the touchscreen 23, it receives operation instructions and outputs control signals to directly control the operation of the sampling valve 71 and the feed pump 622. It also controls the feed three-way solenoid valve 62131, the quantitative three-way solenoid valve 62132, the ethanol feed three-way solenoid valve 62133, the Karl Fischer feed three-way solenoid valve 62134, the reagent pump 623, and the light source emission through the extended I / O module. The system operates through module 61211, a stirring module consisting of stirring motor 61222 and magnetic stir bar 6114, and electrolysis electrode 6113. Meanwhile, the light receiving module 61212, potential electrode 6112, and weighing sensor 61223 transmit the collected signals to PLC controller 21 via extended I / O module. PLC controller 21 summarizes and calculates the input data to obtain the moisture detection and analysis results. All operations of the PLC control system can be completed through touch screen 23, and all parameters and results are displayed in real time through touch screen 23, improving the ease of operation and automation.

[0056] The method for detecting trace moisture content in liquids such as electrolytes using an online trace moisture analyzer based on dual detection modes includes the following steps: S1: Water removal: The first gas dehydrator 53 and the second gas dehydrator 63 are in operation, and the water in containers such as Karl Fischer reagent bottle 51, ethanol reagent bottle 52, and electrolysis tank 6111 is removed through the first gas dehydrator 53 and the second gas dehydrator 63. S2: Wiring: Connect the wires through the explosion-proof wiring port 24 to the wiring assembly inside the electrical control box 2 to complete the wiring between the analyzer and the external power supply and signal source. Ensure that the power supply is properly grounded and the power supply voltage is 220V / 50HZ. Ensure that the wiring assembly inside the box is reliably connected to the PLC controller 21 and the positive pressure control system 8, as well as the PLC controller 21 is reliably connected to each component of the sampling assembly and the detection assembly. S3: Confirm that the pipelines between reagent supply component 5, electrolytic photometric detection device 61, liquid inlet device 62, second gas dehydrator 63, and sampling component 7 are installed and connected correctly, the relevant pipeline lengths for sampling meet the requirements, and ensure that there is no looseness in the pipeline joints and that the materials flow normally without leakage. S4: Accurately prepare Karl Fischer reagent and anhydrous ethanol into Karl Fischer reagent bottle 51 and ethanol reagent bottle 52, respectively; S5: Power On and Positive Pressure Regulation: Turn on the power switch 25 of the electrical control box 2 to power on the reagent pump 623, feed pump 622, electrolytic photometric detection device 61, sampling assembly 7, and positive pressure control system 8, ensuring that the potential electrode 6112, stirring motor 61222, weighing sensor 61223, first gas dehydrator 53, and second gas dehydrator 63 are always in working condition; regulate the gas positive pressure protection of the explosion-proof cabinet 1 through the positive pressure controller 81, connect nitrogen gas through a pipeline to the gas inlet of the positive pressure control pressure reducing valve 83, and after the gas pressure is reduced by the positive pressure control pressure reducing valve 83, adjust the flow regulating valve 84 of the positive pressure control solenoid valve 82 to adjust the pressure of the positive pressure control pressure reducing valve 83 to the specified pressure requirement, such as 0.1MPa, so that the gas pressure entering the explosion-proof cabinet 1 meets the process requirements; performing positive pressure protection regulation can effectively prevent corrosive gases from entering the explosion-proof cabinet 1 and corroding the cabinet body and various components; S6: Inject Karl Fischer reagent into the electrolysis vessel 6111 of the electrolysis detection device 611: The feed three-way solenoid valve 62131 controls the connection between the first intermediate flow channel 621207 and the detector flow channel 621202. Simultaneously, the quantitative three-way solenoid valve 62132 controls the connection between the second intermediate flow channel 621208 and the reagent pump flow channel 621204. The ethanol feed three-way solenoid valve 62133 controls the connection between the third intermediate flow channel 621209 and the fourth intermediate flow channel 621210. Simultaneously, the Karl Fischer feed three-way solenoid valve 62134 controls the connection between the fourth intermediate flow channel 621210 and the Karl Fischer flow channel 621206. The reagent pump 623 operates in the forward direction, injecting the Karl Fischer reagent from the Karl Fischer reagent bottle 51 into the electrolysis tank 6111 of the electrolysis detection device 611 via pipeline and manifold assembly 621. The stirring motor 61222 in the photometric detector 612 is in working condition, stirring the reagent in the electrolytic tank 6111 of the electrolytic detection device 611. At the same time, the weighing sensor 61223 is in working condition. After the weighing sensor 61223 displays that the set weight has been reached, the Karl Fischer feed three-way solenoid valve 62134 controls the fourth intermediate flow channel 621210 and the Karl Fischer flow channel 621206 to disconnect and connect with the fifth intermediate flow channel 621211. Nitrogen gas dried by the second gas dehydrator 63 is introduced from the other end of the fifth intermediate flow channel 621211 through the air inlet channel 621111, and all the remaining Karl Fischer reagent in the pipeline is injected into the electrolytic tank 6111 of the electrolytic detection device 611. The equilibrium potential of the Karl Fischer reagent in the electrolysis tank 6111 is set to A, and the allowable deviation of the potential value is ±b, where b>0. At the same time as the Karl Fischer reagent is added, the potential electrode 6112 is also in working state. When the potential value of the Karl Fischer reagent is detected to exceed (A+b), the PLC controller 21 controls the electrolysis electrode 6113 to work, decompose the water in the Karl Fischer reagent, and reduce the potential value of the Karl Fischer reagent to the range of (Ab)~(A+b), so that the Karl Fischer reagent is in electrolytic equilibrium state, which meets the condition of the sample-ready liquid. For example, when the equilibrium potential value A of the Karl Fischer reagent is set to 300 and the allowable deviation value b is 5, when the potential value of the Karl Fischer reagent is detected to be 300+50, i.e. 350, the PLC controller 21 controls the electrolytic electrode 6113 to work, decompose the water in the Karl Fischer reagent, and reduce the potential value of the Karl Fischer reagent to the range of 295~305, so that the Karl Fischer reagent is in an electrolytic equilibrium state, which meets the condition of the sample-ready liquid. At this time, the light source emitting module 61211 is activated to emit light, and the light receiving module 61212 receives the light emitted by the light source emitting module 61211 and after passing through the Karl Fischer reagent in the electrolysis tank 6111. The PLC controller 21 records the light value received by the light receiving module 61212 at this time. S7: Add sample solution to electrolytic vessel 6111: The feed three-way solenoid valve 62131 first controls the connection between the first intermediate flow channel 621207 and the feed pump flow channel 621201. Simultaneously, the quantitative three-way solenoid valve 62132 controls the connection between the second intermediate flow channel 621208 and the recovery flow channel 621203. The sampling valve 71 is opened, and the feed pump 622 operates. Sample liquid is first introduced into the feed pump flow channel 621201, the first intermediate flow channel 621207, the recovery flow channel 621203, the second intermediate flow channel 621208, and the spiral pipe 621212 for a certain period of time to perform material replacement. After replacement, sample liquid is introduced again for a certain period of time. Then, the feed three-way solenoid valve 62131 controls the connection between the first intermediate flow channel 621207 and the detector. When flow channel 621202 is turned on, the quantitative three-way solenoid valve 62132 controls the second intermediate flow channel 621208 to be connected to the reagent pump flow channel 621204. The ethanol feed three-way solenoid valve 62133 controls the third intermediate flow channel 621209 and the fourth intermediate flow channel 621210 to be connected. The Karl Fischer feed three-way solenoid valve 62134 controls the fourth intermediate flow channel 621210 and the fifth intermediate flow channel 621211 to be connected. The reagent pump 623 runs in the forward direction. Under the action of nitrogen gas dried by the second gas dehydrator 63 and introduced through the air inlet channel 621111, the quantitative sample liquid in the spiral pipe 621212 is pumped into the electrolysis tank 6111 of the electrolysis detection device 611. S8: Segmented Detection Analysis: Let c be a value greater than b. The water content of the liquid to be tested is divided into two intervals in advance. After the sample liquid is added to the electrolysis vessel 6111, the potential value of the mixed liquid after the sample liquid is added is detected by the potential electrode 6112. If the potential value is within the range of (A+b) to (A+c), it is the low water content segment. If the potential value is greater than (A+c), it is the high water content segment. After the sample solution is added, when the potential electrode 6112 detects that the potential value of the mixed liquid is between (A+b) and (A+c), the system automatically determines that it is in the low moisture content range and starts the photometric detection method to detect the moisture content. The light source emission module 61211 emits light, and the light receiving module 61212 receives the light emitted by the light source emission module 61211 and passes through the mixed liquid inside the electrolysis tank 6111. The PLC controller 21 records the light value received by the light receiving module 61212 at this time, and directly calculates the moisture content in the sample solution based on the difference in light value before and after the sample solution is added. After the detection is completed, the electrolysis electrode 6113 works to bring the potential value of the mixed liquid back to the equilibrium potential state, that is, the range of (Ab) to (A+b), and then waits for the next detection. After the sample solution is added, when the potential electrode 6112 detects a potential value greater than (A+c), the system automatically determines it to be in a high moisture content range, initiates the Karl Fischer coulometric method to detect the moisture content, the electrolysis electrode 6113 is activated, and the PLC controller 21 collects the electrolysis current signal in real time and integrates the current over time to obtain the total electrolysis charge Q that brings the potential value back to equilibrium. The system then automatically calculates the moisture content in the sample solution according to the following formula: ; Wherein: W is the water content in the sample solution, in μg; Q represents the amount of electricity consumed by the electrolytic electrode to electrolyze water in the sample solution, expressed in mC. 18 is the molecular weight of water; 96485 is the number of millicoulombs of electricity required to electrolyze 1 millimole of water; For example, if the ambient temperature of the electrolytic vessel 6111 is 25℃, the blank moisture content is 2ppm, and the equilibrium potential value A of the Karl Fischer reagent is set to 300, the allowable deviation value b is 5, and the c value is 30, when the potential electrode 6112 detects a mixed liquid potential value of 328 after the sample solution is added, the system uses automatic photometric detection. Before the sample solution is added, the initial light value M received by the light receiving module 61212 is 20000, representing the light value at equilibrium. After the sample solution is added, the light value M received by the light receiving module 61212 is 21000. Therefore, at this time... The difference in light value after adding the sample solution is 21000-20000, and the result is 1000. According to the pre-calibrated ratio of the difference in light value to the water content is 100:1, the water content in the mixed liquid after adding the sample solution can be directly calculated by the PLC controller as [(1000*1) / 100-2] ppm, which is 8 ppm. The larger the result, the higher the water content. After the detection is completed, the electrolytic electrode 6113 works to bring the potential value of the mixed liquid back to the equilibrium potential range of 295~305 and wait for the next detection. For example, if the ambient temperature of the electrolysis tank 6111 is 25℃, and the sample solution is added with a mass of 0.2g, the equilibrium potential value A of the Karl Fischer reagent is 300, the allowable deviation b is 5, and the c is 30, the blank power consumption per second is 1.5mC. When the potential electrode 6112 detects a potential value of 410 for the mixed liquid in the electrolysis tank 6111, the system automatically starts the Karl Fischer coulometric method to detect the moisture content, the electrolysis electrode 6113 is activated, and the PLC controller 21 collects the electrolysis current signal in real time and integrates the current over time to obtain the total electrolysis power Q. The electrolysis time and the corresponding potential, current, and electrolysis power data are shown in Table 1. Table 1. Data on electrolysis time and corresponding potential, current, and electrolysis charge. 1s 410 100 100 2s 387 80 80 3s 351 50 50 4s 322 20 20 5s 315 15 15 6s 307 5 5 7s 306 5 5 8s 305 5 5 From Table 1, we can see that the total electrolysis time is 8s to bring the potential of the mixed liquid to a balanced state, and the total power consumption is 280mC. Subtracting the blank power of 8×1.5mC, the actual electrolysis power is 268mC. Substitution The water content of the sample solution was calculated to be: W = 25 μg; Converted to ppm, it is 0.025 mg / 0.0002 kg, which means the water content in the sample solution is 125 ppm. This result is then displayed on the touch screen 23 and fed back to the operator for processing. S9: Drainage: When the total weight of Karl Fischer reagent and sample solution in the electrolysis tank 6111 of the electrolysis detection device 611 reaches the set upper limit, all liquid in the electrolysis tank 6111 needs to be discharged. At this time, the reagent pump 623 reverses, and the feed three-way solenoid valve 62131 and the quantitative three-way solenoid valve 62132 are respectively connected to the detector flow channel 621202 and the reagent pump flow channel 621204. In the default state, the third intermediate flow channel 621209 is connected to the fourth intermediate flow channel 621210, and the other end of the fourth intermediate flow channel 621210 is connected to one end of the fifth intermediate flow channel 621211. One end of the tank 621211 is also connected to the waste liquid discharge channel 621110. In this way, the feed three-way solenoid valve 62131 and the metering three-way solenoid valve 62132 are opened, and all the mixed liquid in the electrolysis tank 6111 is discharged into the waste liquid pool through the detector flow channel 621202, the first intermediate flow channel 621207, the spiral pipe 621212, the second intermediate flow channel 621208, the reagent pump flow channel 621204, the reagent pump 623, the third intermediate flow channel 621209, the fourth intermediate flow channel 621210, the fifth intermediate flow channel 621211 and the waste liquid discharge channel 621110. S10: Cleaning with anhydrous ethanol: When reagent pump 623 is started and rotated forward, the feed three-way solenoid valve 62131, the metering three-way solenoid valve 62132, and the ethanol feed three-way solenoid valve 62133 open. At this time, the feed three-way solenoid valve 62131 is connected to the detector flow channel 621202, which is connected to the first intermediate flow channel 621207. The first intermediate flow channel 621207 is connected to the second intermediate flow channel 621208 via a spiral pipe 621212. 1208 is connected to the reagent pump flow channel 621204. One end of the third intermediate flow channel 621209 is connected to the reagent pump 623, and the other end is connected to the ethanol flow channel 621205 through the ethanol feed three-way solenoid valve 62133. The anhydrous ethanol in the ethanol reagent bottle 52 enters the electrolytic detection device 611 under the action of the reagent pump 623. The anhydrous ethanol cleans the electrolytic detection device 611. The waste liquid after cleaning is discharged according to step S9. After the liquid is discharged, the cleaning is completed.

[0057] It should be further explained that the equilibrium potential value A, the allowable deviation value b, and the boundary value (A+c) between the low and high moisture content sections after adding the sample solution in the electrolysis vessel 6111 are set according to specific circumstances and requirements to meet the requirements of specific testing scenarios and ensure the accuracy of the test results. Meanwhile, generally, since the environment in which the electrolysis vessel 6111 is located is not completely sealed, there will always be some moisture present. Even when standard Karl Fischer reagent is added to the electrolysis vessel 6111, the actual detected potential value is generally higher than the equilibrium potential value. After adding the sample solution, the potential value is generally even higher than this equilibrium potential value. The electrolysis electrode 6113 is activated to electrolyze the moisture in the Karl Fischer reagent or the mixture of Karl Fischer reagent and sample solution. When the potential electrode 6112 detects that the potential value reaches the equilibrium set value A or the deviation (A+b) above the set value, the power supply to the electrolysis electrode 6113 will be cut off. However, due to the time delay between the power cut-off action and the actual cessation of electrolysis, over-electrolysis of the liquid may occur, that is, electrolysis of very low water content in the liquid, resulting in the final liquid potential value being lower than the equilibrium potential setting value A. However, the potential value is generally not lower than (Ab). If severe over-electrolysis occurs due to circuit abnormalities, causing the potential value to be lower than (Ab), it is necessary to completely cut off the power supply to the electrolysis electrode 6113 and simultaneously introduce air into the electrolysis tank 6111 for a certain period of time to restore the liquid potential value to the allowable deviation range of the equilibrium setting value.

[0058] It should also be noted that the light emission module 61211 and the light receiving module 61212 can move synchronously along the circumferential direction of the upper surface of the mounting ring 61215 and move up and down through the mounting ring 61215 to measure the light value multiple times from different angles and heights, and calculate the moisture content at different locations. This can avoid measurement errors caused by uneven mixing, as well as measurement errors caused by contamination from the electrolysis tank wall and other factors, and can also be applied to different detection scenarios.

[0059] The above embodiments of the present invention are not intended to limit the scope of protection of the present invention. The implementation of the present invention is not limited thereto. All other modifications, substitutions or alterations made to the above structure of the present invention based on the above content of the present invention, in accordance with ordinary technical knowledge and common practice in the field, without departing from the basic technical idea of ​​the present invention, shall fall within the scope of protection of the present invention.

Claims

1. A trace moisture online analyzer based on dual detection modes, comprising an explosion-proof cabinet, a PLC control system, and a positive pressure control system, wherein the explosion-proof cabinet includes an analysis cabinet located at its lower part and an electrical control box located above the analysis cabinet, and the PLC control system includes a PLC controller installed inside the electrical control box, characterized in that, The analysis cabinet is equipped with an analysis component, which includes a detection component located at the top of the cabinet and a reagent supply component at the bottom of the cabinet for supplying Karl Fischer reagent and anhydrous ethanol to the detection component. The detection component includes an electrolytic photometric detection device located above the reagent supply component and a liquid inlet device fixed inside the analysis cabinet. The electrolytic photometric detection device includes an electrolytic detection device with reagent and sample inlet and outlet interfaces, a potential electrode for accommodating sample and reagent and equipped with a detection potential, an electrolytic electrode for electrolyzing water, a photometric detector located below the electrolytic detection device to support it, a photometric detector with a light source emitting module and a light receiving module symmetrically arranged inside and equipped with a weighing sensor, and a stirring module for stirring the sample and reagent. The liquid inlet device includes a manifold valve plate assembly connected to the electrolytic detection device via a pipeline, and a reagent pump and a feed pump connected to the manifold valve plate assembly via a pipeline. The analysis cabinet is also equipped with a sampling component connected to the feed pump via a pipeline. The electrolytic photometric detection device, the liquid inlet device, the sampling component, and the PLC controller are connected via wires.

2. The online trace moisture analyzer based on dual detection modes according to claim 1, characterized in that, The PLC control system also includes a touch screen installed on the front door of the electrical control box and supporting software running on the touch screen and the PLC controller. The electrical control box also contains a switching power supply, a power switch, and an internal wiring assembly for connecting external wires and connecting to the PLC controller and the positive pressure control system via wires. An explosion-proof wiring port is provided on one side of the outer wall of the electrical control box.

3. The online trace moisture analyzer based on dual detection modes according to claim 1, characterized in that, The reagent supply assembly includes a Karl Fischer reagent bottle containing Karl Fischer reagent, an ethanol reagent bottle containing anhydrous ethanol, and a first gas dehydrator connected to the Karl Fischer reagent bottle and the ethanol reagent bottle via pipelines. The electrolysis detection device and the manifold valve plate assembly are also connected to the second gas dehydrator fixed inside the analysis cabinet via pipelines.

4. The online trace moisture analyzer based on dual detection modes according to claim 3, characterized in that, The electrolytic detection device includes an electrolytic vessel containing sample solution and reagents. The electrolytic electrode and potential electrode are inserted into the top of the electrolytic vessel and extend into the interior of the electrolytic vessel. The top of the electrolytic vessel is also provided with an air vent connected to the second gas dehydrator through a pipeline and an inlet / outlet connected to the manifold valve plate assembly through a pipeline. A magnetic stir bar is provided inside the electrolytic vessel. A manual liquid filling port is also provided on one side wall of the electrolytic vessel, and a manual liquid filling port plug is provided on the manual liquid filling port. The photometric detector includes a detector housing for placing an electrolysis detection device and a base disposed inside the lower part of the detector housing. The detector housing is a hollow shell and is fixed to the analysis cabinet. The light source emitting module and the light receiving module are symmetrically installed on the side wall of the lower middle part of the detector housing. A terminal post is provided on one outer wall of the detector housing. The upper shell wall of the detector housing is provided with a locking groove for locking the manual liquid filling port of the electrolysis tank. A base plate is fixed to the bottom of the detector housing. The base is fixedly installed on the base plate. The upper part of the base is a tray for placing the electrolysis detection device, and the lower part is equipped with a stirring motor with a magnet installed at the output end. The weighing sensor is installed at the bottom of the base. The potential electrode, electrolytic electrode, light source emitting module, light receiving module, weighing sensor, stirring motor, and terminal block are connected by wires, and are also connected to the PLC controller via wires through the terminal block.

5. The online trace moisture analyzer based on dual detection modes according to claim 4, characterized in that, The manifold valve plate assembly includes a stainless steel connector seat, a stainless steel valve seat, and a PTFE sealing gasket with several through-flow grooves fixedly pressed between the stainless steel connector seat and the stainless steel valve seat; a feed three-way solenoid valve, a metering three-way solenoid valve, an ethanol feed three-way solenoid valve, and a Karl Fischer feed three-way solenoid valve are fixedly installed on the stainless steel valve seat, and the feed three-way solenoid valve, metering three-way solenoid valve, ethanol feed three-way solenoid valve, and Karl Fischer feed three-way solenoid valve are connected to the PLC controller through wires. The stainless steel valve seat is provided with three interface through holes that communicate with the feed three-way solenoid valve, the metering three-way solenoid valve, the ethanol feed three-way solenoid valve and the Karl Fischer feed three-way solenoid valve. The stainless steel connector seat is provided with a feed through hole, a detector through hole, a first reagent pump through hole, a recovery through hole, a second reagent pump through hole, a first quantitative tube connection through hole, a second quantitative tube connection through hole, an ethanol through hole, and a Karl Fischer through hole. The through-flow channels on the PTFE gasket include a feed pump channel, a detector channel, a recovery channel, a reagent pump channel, an ethanol channel, a Karl Fischer channel, and a first intermediate channel, a second intermediate channel, a third intermediate channel, a fourth intermediate channel, and a fifth intermediate channel, all extending through its thickness direction. The feed pump channel and the detector channel are integrally located on opposite sides of the same end of the first intermediate channel, with each having one end adjacent to that end of the first intermediate channel. The recovery channel and the reagent pump channel are integrally located on opposite sides of the same end of the second intermediate channel, with each having one end adjacent to that end of the second intermediate channel. The detector channel, reagent pump channel, ethanol channel, and Karl Fischer channel are located on one side of the same long side of the PTFE gasket. The detector channel and the reagent pump channel are adjacent to each other and arranged sequentially from the outside to the inside along the length direction of the PTFE gasket, starting from the position closest to one side of the wide side. The adjacent ends of the feed pump channel, the detector channel, and the first intermediate channel are respectively connected to the three ports of the feed three-way solenoid valve through corresponding interface holes on the stainless steel valve seat. The other end of the feed pump channel is connected to the feed pump through the feed through hole via a pipeline. The other end of the detector channel is connected to the inlet and outlet of the electrolysis tank through the detector through the detector through the through hole via a pipeline. The adjacent ends of the recovery channel, the reagent pump channel, and the second intermediate channel are respectively connected to the three ports of the quantitative three-way solenoid valve through corresponding interface holes on the stainless steel valve seat. The other end of the recovery channel is connected to the externally installed recovery tank through the recovery through the recovery through hole via a pipeline. The other end of the reagent pump channel is connected to the output end of the reagent pump through the first through hole of the reagent pump via a pipeline. The third intermediate flow channel is connected to one end of the ethanol flow channel and one end of the fourth intermediate flow channel, and is connected to the three ports of the ethanol feed three-way solenoid valve through corresponding interface holes on the stainless steel valve seat. The other end of the third intermediate flow channel is connected to the input end of the reagent pump through the second through hole of the reagent pump via a pipeline. The other end of the ethanol flow channel is connected to the ethanol reagent bottle through a pipeline through an ethanol through hole. The other end of the fourth intermediate flow channel, one end of the Karl Fischer flow channel, and one end of the fifth intermediate flow channel are adjacent to each other and are connected to the three ports of the Karl Fischer feed three-way solenoid valve through corresponding interface holes on the stainless steel valve seat. The other end of the Karl Fischer flow channel is connected to the Karl Fischer reagent bottle through a Karl Fischer through hole via a pipeline. The other end of the first intermediate flow channel, which is not adjacent to the flow channel of the feed pump and the flow channel of the detector, is connected to the first through hole of the quantitative tube. The other end of the second intermediate flow channel, which is not adjacent to the flow channel of the recovery channel and the flow channel of the reagent pump, is connected to the second through hole of the quantitative tube. A spiral pipe is connected between the first through hole of the quantitative tube and the second through hole of the quantitative tube. The two sides of the long side of the stainless steel connector are respectively provided with an air inlet channel and a waste liquid discharge channel that communicate with both ends of the fifth intermediate flow channel. The air inlet channel and the through hole of the detector are located on the same half of the stainless steel connector, and the inlet of the air inlet channel is opened on the long side of this side and is connected to the second gas dehydrator through a pipeline. The outlet of the air inlet channel is opened on the surface of the stainless steel connector that is in contact with the PTFE sealing gasket and is connected to the other end of the fifth intermediate flow channel. The waste liquid discharge channel and the feed through hole are located on the same half of the stainless steel connector, and the outlet of the waste liquid discharge channel is opened on the long side of this side and is connected to the waste liquid pool through a pipeline. The inlet of the waste liquid discharge channel is opened on the surface of the stainless steel connector that is in contact with the PTFE sealing gasket and is connected to one end of the fifth intermediate flow channel. The feed three-way solenoid valve is synchronized with the feed pump, and the quantitative three-way solenoid valve is synchronized with the externally installed recovery tank; the feed three-way solenoid valve is synchronized with the electrolytic photometric detection device, and the quantitative three-way solenoid valve is synchronized with the reagent pump.

6. The online trace moisture analyzer based on dual detection modes according to claim 5, characterized in that, The feed through-hole, detector through-hole, reagent pump first through-hole, recovery through-hole, reagent pump second through-hole, quantitative tube connection first through-hole, quantitative tube connection second through-hole, ethanol through-hole, and Karl Fischer through-hole are each composed of a smooth through-hole section and a threaded through-hole section connected to the smooth through-hole section. The smooth through-hole section is located on the side that is in contact with the PTFE gasket and is connected to the feed pump channel, detector channel, reagent pump channel, recovery channel, third intermediate channel, first intermediate channel, second intermediate channel, ethanol channel, and Karl Fischer channel, respectively. The threaded through-hole section is located on the side away from the PTFE gasket and is connected to the feed pump, electrolytic photometric detection device, reagent pump output end, recovery tank, reagent pump input end, both ends of the spiral pipe, ethanol reagent bottle, and Karl Fischer reagent bottle through pipelines. The smooth through-hole section and the threaded through-hole section are sealed together, and the inner diameter of the threaded through-hole section is larger than the inner diameter of the smooth through-hole section. Both the air intake channel and the waste liquid discharge channel consist of an L-shaped smooth inner hole section directly connected to the fifth intermediate flow channel and an internally threaded hole section connected to the L-shaped smooth inner hole section. The internally threaded hole section of the air intake channel is connected to the second gas dehydrator through a pipeline, and the internally threaded hole section of the waste liquid discharge channel is connected to the waste liquid pool through a pipeline. The L-shaped smooth inner hole section and the internally threaded hole section of the air intake channel and the waste liquid discharge channel are sealed together, and the inner diameter of the internally threaded hole section is larger than the inner diameter of the L-shaped smooth inner hole section.

7. The online trace moisture analyzer based on dual detection modes according to claim 1, characterized in that, The sampling assembly includes a sampling valve disposed on one outer wall of the analysis cabinet and connected to the input end of the feed pump via a pipeline; a pneumatic solenoid valve connected to the control end of the sampling valve via a pipeline and controlling the opening and closing of the sampling valve; and a sampling pressure reducing valve connected to the other end of the pneumatic solenoid valve to control the airflow pressure of the pneumatic solenoid valve, the other end of which is connected to compressed gas; both ends of the sampling valve are respectively connected to the production pipeline via pipelines.

8. The online trace moisture analyzer based on dual detection modes according to claim 2, characterized in that, The positive pressure control system is installed on the other side of the analysis cabinet. The positive pressure control system includes a positive pressure controller installed on the other side of the analysis cabinet, a positive pressure control solenoid valve connected to the positive pressure controller and controlled to open and close by the positive pressure controller, a positive pressure control pressure reducing valve connected to one end of the positive pressure control solenoid valve, a flow regulating valve installed on the positive pressure control solenoid valve, the other end of the flow regulating valve outlet is located inside the explosion-proof cabinet, and the other end of the positive pressure control pressure reducing valve is connected to compressed nitrogen. The positive pressure control system also includes a pressure sensor installed inside the analysis cabinet. The positive pressure controller and the positive pressure control solenoid valve are connected to the internal wiring assembly inside the electrical control box via wires.

9. The online trace moisture analyzer based on dual detection modes according to claim 4, characterized in that, An installation ring is also installed on the lower inner side wall of the detector housing. An annular vertical rack is provided on the upper inner section of the installation ring. The light source emitting module and the light receiving module are installed on the upper end face of the installation ring. A drive motor is installed on the light source emitting module and the light receiving module respectively. A gear that meshes with the annular vertical rack on the upper inner section of the installation ring is installed on the output end of the drive motor. Two installation ring lifting cylinders are symmetrically installed below the installation ring. The installation ring lifting cylinders are installed as a whole on the lower inner side wall of the detector housing. The output end of the installation ring lifting cylinder is connected to the lower end face of the installation ring.

10. A method for detecting trace moisture content using an online trace moisture analyzer based on dual detection modes according to any one of claims 1-9, characterized in that, Includes the following steps: S1: Dehydration: The first and second gas dehydrators operate to remove moisture from Karl Fischer reagent bottles, ethanol reagent bottles, and electrolysis tanks; S2: Wiring: Connect the wires through the explosion-proof wiring port to the wiring assembly inside the electrical control box to ensure reliable wiring between the wiring assembly inside the box and the PLC controller and the positive pressure control system; S3: Confirm that the pipelines between the reagent supply component, electrolytic photometric detection device, liquid inlet device, second gas dehydrator, and sampling component are installed and connected correctly, the relevant pipeline lengths for sampling meet the requirements, the pipeline joints are not loose, and the materials flow normally without leakage. S4: Accurately prepare Karl Fischer reagent and anhydrous ethanol into Karl Fischer reagent bottle and ethanol reagent bottle, respectively; S5: Power On and Positive Pressure Regulation: Turn on the power switch to power on the reagent pump, feed pump, electrolytic photometric detection device, positive pressure control system, and sampling components, ensuring that the potential electrode, stirring motor, and weighing sensor are in working condition; the positive pressure controller regulates the gas positive pressure protection of the explosion-proof cabinet, connects nitrogen to the gas inlet of the positive pressure control pressure reducing valve, and after the pressure is reduced by the positive pressure control pressure reducing valve, adjusts the flow regulating valve to ensure that the gas pressure entering the explosion-proof cabinet meets the process requirements; S6: Injecting Karl Fischer reagent into the electrolysis tank: The feed three-way solenoid valve controls the first intermediate flow channel to connect with the detector flow channel, while the quantitative three-way solenoid valve controls the second intermediate flow channel to connect with the reagent pump flow channel. The ethanol feed three-way solenoid valve controls the third and fourth intermediate flow channels to connect, and the Karl Fischer feed three-way solenoid valve controls the fourth intermediate flow channel to connect with the Karl Fischer flow channel. The reagent pump runs in the forward direction, injecting Karl Fischer reagent into the electrolysis tank. The stirring motor drives the magnetic stir bar to stir the reagent in the electrolysis tank. When the weighing sensor shows that the set weight has been reached, the Karl Fischer feed three-way solenoid valve controls the fourth intermediate flow channel and the Karl Fischer flow channel to disconnect and connect with the fifth intermediate flow channel. Nitrogen gas dried by the second gas dehydrator is introduced from the other end of the fifth intermediate flow channel through the air inlet channel, injecting all the remaining Karl Fischer reagent in the pipeline into the electrolysis tank. The equilibrium potential of the Karl Fischer reagent in the electrolysis vessel is set to A, and the allowable deviation of the potential value is ±b, where b>0. After the Karl Fischer reagent is added, when the potential electrode detects that the potential value of the Karl Fischer reagent exceeds (A+b), the PLC controller controls the electrolysis electrode to work, decompose the water in the Karl Fischer reagent, and reduce the potential value of the Karl Fischer reagent to the range of (Ab)~(A+b), so that the Karl Fischer reagent is in an electrolytic equilibrium state, which meets the condition of the sample-ready liquid. At this time, the light source emitting module is activated to emit light, and the light receiving module receives the light emitted by the light source emitting module after passing through the Karl Fischer reagent in the electrolysis tank. The PLC controller records the light value received by the light receiving module at this time. S7: Adding sample solution to the electrolysis tank: The feed three-way solenoid valve first controls the connection between the first intermediate flow channel and the feed pump flow channel, while the quantitative three-way solenoid valve controls the connection between the second intermediate flow channel and the recovery flow channel. The sampling valve is opened, and the feed pump works. Sample solution is first introduced into the feed pump flow channel, the first intermediate flow channel, the recovery flow channel, the second intermediate flow channel, and the spiral pipe for a certain period of time to perform material replacement. After the replacement is completed, sample solution is introduced again for a certain period of time. Then, the feed three-way solenoid valve controls the connection between the first intermediate flow channel and the detector flow channel, while the quantitative three-way solenoid valve controls the connection between the second intermediate flow channel and the reagent pump flow channel. The ethanol feed solenoid valve controls the connection between the third and fourth intermediate flow channels, and the Karl Fischer feed three-way solenoid valve controls the connection between the fourth and fifth intermediate flow channels. The reagent pump runs in the forward direction. Under the action of the dried nitrogen gas introduced through the air inlet channel, a quantitative sample solution in the spiral pipe is pumped into the electrolysis tank. S8: Segmented detection and analysis: Let c be a value greater than b. The water content of the liquid is divided into two intervals in advance. After the sample liquid is added to the electrolysis tank, the potential value of the mixed liquid after the sample liquid is added is within the range of (A+b) to (A+c). This is the low water content segment. The potential value of the mixed liquid after the sample liquid is added is within the range of (A+b) to (A+c). This is the high water content segment. When the potential value is displayed in the low moisture content range after the sample solution is added, the system automatically starts the photometric detection method. The light source emission module emits light, and the light receiving module receives the light passing through the mixed liquid in the electrolysis tank. The PLC controller records the light value received by the light receiving module at this time, and calculates the moisture content in the sample solution based on the difference in light value before and after the sample solution is added. After the detection is completed, the electrolysis electrode is activated to bring the potential value of the mixed liquid back to the equilibrium state and wait for the next detection. When the potential value is displayed in the high moisture content range after the sample solution is added, the system automatically starts the Karl Fischer coulometric method, the electrolysis electrode is activated, the PLC controller collects the electrolysis current signal in real time, and integrates the current over time to obtain the total electrolysis charge Q that brings the potential value back to equilibrium. The system then automatically calculates the moisture content in the sample solution according to the following formula: ； Wherein: W is the water content in the sample solution, in μg; Q represents the amount of electricity consumed by the electrolytic electrode to electrolyze water in the sample solution, expressed in mC. 18 is the molecular weight of water; 96485 is the number of millicoulombs of electricity required to electrolyze 1 millimole of water; S9: Drainage: When the total weight of Karl Fischer reagent and sample liquid in the electrolysis tank reaches the set upper limit, the reagent pump is started in reverse. The feed three-way solenoid valve and the quantitative three-way solenoid valve are connected to the detector flow channel and the reagent pump flow channel, respectively. The third intermediate flow channel is connected to the fourth intermediate flow channel, the fifth intermediate flow channel and the waste liquid discharge channel in sequence. The feed three-way solenoid valve and the quantitative three-way solenoid valve are opened. All the mixed liquid in the electrolysis tank is discharged into the waste liquid pool in sequence through the detector flow channel, the first intermediate flow channel, the spiral pipe, the second intermediate flow channel, the reagent pump flow channel, the reagent pump, the third intermediate flow channel, the fourth intermediate flow channel, the fifth intermediate flow channel and the waste liquid discharge channel. S10: Anhydrous ethanol cleaning: Start the reagent pump to rotate forward. The feed three-way solenoid valve is connected to the detector flow channel. The detector flow channel is connected in sequence to the first intermediate flow channel, the spiral pipe, the second intermediate flow channel, the reagent pump flow channel, and the reagent pump. One end of the third intermediate flow channel is connected to the reagent pump, and the other end is connected to the ethanol flow channel through the ethanol feed three-way solenoid valve. Open the feed three-way solenoid valve, the metering three-way solenoid valve, and the ethanol feed three-way solenoid valve to allow anhydrous ethanol to enter the electrolysis tank and clean the electrolysis tank. The waste liquid after cleaning is discharged according to step S9. The cleaning is completed after the liquid is discharged.

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