Pressure self-balancing deoxygenation working condition electrochemical measuring device and method

Abstract

The application belongs to the technical field of electrochemical measurement, and discloses a pressure self-balancing deoxygenation working condition electrochemical measurement device and method, which comprises a differential pressure transmitter, a PLC liquid level controller, an oxygen content measuring instrument, a first measurement pool, a second measurement pool, an oxygen content measurement pool and a water seal pool; the first measurement pool, the second measurement pool, the oxygen content measurement pool and the water seal pool are sequentially communicated through deoxygenation pipelines; an auxiliary electrode and a working electrode are arranged in the first measurement pool; the second measurement pool is provided with a reference electrode; the auxiliary electrode, the working electrode and the reference electrode are electrically connected with an electrochemical workstation; a salt bridge is further arranged between the first measurement pool and the second measurement pool; the second measurement pool is arranged on a lifting device, and the second measurement pool and the first measurement pool form a height difference h. The application utilizes a control system to automatically control the liquid level difference balance of the measurement device to balance the pressure difference generated by the deoxygenation nitrogen gas flow, and the measurement accuracy is high.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical measurement technology research, specifically relating to an electrochemical measurement device and method for pressure self-balancing deoxygenation conditions. Technical Background

[0002] Dissolved oxygen, acting as a depolarizer, is a significant factor affecting metal corrosion and severely impacts the measurement results of metal electrochemical corrosion. Since oxygen is ubiquitous in the air, it easily enters the measuring device. Furthermore, within the sealed measuring device, insufficient circulation and exchange create dead zones, resulting in inconsistent oxygen content between these zones and other areas, severely affecting measurement accuracy. Summary of the Invention

[0003] To study the corrosion behavior of metals under deoxygenation conditions and to accurately perform electrochemical measurements, this invention provides a pressure self-balancing electrochemical measurement device and method under deoxygenation conditions. This device is the most effective electrochemical measurement method for measuring the corrosion behavior of metals under oxygen-free conditions. It utilizes the flow of high-purity nitrogen to deoxygenate the measuring device and uses a control system to automatically control the liquid level difference of the measuring device to balance the pressure difference generated by the nitrogen flow. It is easy to operate, has good stability, and high measurement accuracy.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] An electrochemical measuring device for pressure self-balancing deoxygenation includes a differential pressure transmitter, a PLC level controller, an oxygen content measuring instrument, a primary measuring cell, a secondary measuring cell, an oxygen content measuring cell, and a water seal cell.

[0006] The primary measuring tank, the secondary measuring tank, the oxygen content measuring tank, and the water seal tank are connected sequentially via a deoxygenation pipeline;

[0007] The primary measuring cell is equipped with an auxiliary electrode and a working electrode, and the secondary measuring cell is equipped with a reference electrode. The auxiliary electrode, working electrode, and reference electrode are all electrically connected to the electrochemical workstation, forming a three-electrode measuring system. A salt bridge is also provided between the primary and secondary measuring cells.

[0008] The secondary measuring pool is mounted on the lifting device, and the secondary measuring pool forms a height difference h with the primary measuring pool.

[0009] The differential pressure transmitter tests the liquid pressure in the primary and secondary measuring cells respectively; an oxygen electrode is provided on the oxygen content measuring cell; the oxygen electrode is electrically connected to the oxygen content measuring instrument; the lifting device and the differential pressure transmitter are both electrically connected to the PLC level controller.

[0010] As a further improvement of the present invention, the deoxygenation pipeline includes a primary deoxygenation pipe, a secondary deoxygenation pipe, a tertiary deoxygenation pipe and a quaternary deoxygenation pipe;

[0011] The primary measuring tank is equipped with a primary deoxygenation pipe. One end of the primary deoxygenation pipe is connected to a nitrogen pipeline, and the other end is placed in the primary measuring tank. The primary measuring tank is connected to the secondary measuring tank through a secondary deoxygenation pipe. The secondary measuring tank is connected to the oxygen content measuring tank through a tertiary deoxygenation pipe. The oxygen content measuring tank is connected to the water seal tank through a quaternary deoxygenation pipe.

[0012] As a further improvement of the present invention, the lifting device includes a stepper motor and a lifting platform. The stepper motor drives the lifting platform to move up and down. The secondary measuring tank is disposed on the lifting platform. The stepper motor is electrically connected to a PLC level controller.

[0013] As a further improvement of the present invention, a salt bridge switching valve is provided on the salt bridge.

[0014] As a further improvement of the present invention, the end of the deoxygenation pipe is placed below the liquid surface.

[0015] As a further improvement of the present invention, the differential pressure transmitter is connected to the primary measuring cell and the secondary measuring cell via a primary measuring cell pressure tube and a secondary measuring cell pressure tube, respectively.

[0016] A measurement method for an electrochemical measuring device operating under pressure self-balancing deoxygenation conditions, comprising:

[0017] Nitrogen flow passes through the primary measuring cell, the secondary measuring cell, the oxygen content measuring cell, and the water seal cell to deoxygenate the entire measuring system;

[0018] Use an oxygen content meter to measure the oxygen concentration in the oxygen content measurement cell to ensure that the oxygen content of the entire measurement system meets the test requirements;

[0019] The differential pressure transmitter measures the pressure difference between the primary and secondary measuring cells, and the measurement signal is transmitted to the PLC level controller. The PLC level controller sends a control signal to the lifting device according to the liquid level fluctuation. The lifting device adjusts the height difference h between the secondary and primary measuring cells to achieve pressure balance.

[0020] As a further improvement of the present invention, the lifting device adjusts the height difference h between the secondary measuring pool and the primary measuring pool to achieve pressure balance, including:

[0021] By measuring the pressure difference between the two measuring tanks and adjusting the height between them, the resistance generated when nitrogen flows through the deoxygenation pipe is balanced by utilizing the liquid level difference between the measuring tanks, and the pressure between the two measuring tanks is always in a balanced state.

[0022] As a further improvement of the present invention, the lifting device adjusts the height difference h between the secondary measuring pool and the primary measuring pool to achieve pressure balance, specifically including:

[0023] When the pressure difference between the primary and secondary measuring tanks increases, the PLC level controller controls the lifting platform to rise, increasing the level difference between the primary and secondary measuring tanks. The level difference balances the pressure difference generated by the nitrogen flow through the secondary deoxygenation pipe, thus balancing the pressure between the primary and secondary measuring tanks.

[0024] When the pressure difference between the primary and secondary measuring tanks decreases, the PLC level controller controls the lifting platform to descend, reducing the level difference between the primary and secondary measuring tanks. This level difference balances the pressure difference generated by the nitrogen flow through the secondary deoxygenation pipe, thus achieving pressure balance between the primary and secondary measuring tanks.

[0025] The technical solution provided by this invention has the following beneficial effects:

[0026] In this invention, the staged flow of high-purity nitrogen effectively removes oxygen from the measuring device. The electrochemical measurement employs a three-electrode system with a salt bridge, minimizing interference from impurity ions and ensuring high accuracy. The control system automatically balances the pressure difference generated by the nitrogen flow using the liquid level difference, resulting in easy operation, good stability, and high measurement accuracy. An oxygen content measuring cell is located at the very end of the measuring device, reflecting the true oxygen content of the entire system, eliminating the need for separate oxygen content measuring systems at each stage and simplifying operation. A water seal tank is located at the very end of the measuring system to prevent oxygen leakage back into the system. To ensure measurement accuracy, the electrochemical measurement uses a three-electrode system, primarily consisting of a working electrode, an auxiliary electrode, and a reference electrode. The control system automatically balances the pressure difference generated by the nitrogen flow using the liquid level difference, resulting in easy operation, good stability, and high measurement accuracy. This invention is the most effective electrochemical measurement method for measuring the corrosion behavior of metals under oxygen-free conditions. It utilizes the flow of high-purity nitrogen to deoxygenate the measuring device and uses a control system to automatically control the liquid level difference of the measuring device to balance the pressure difference generated by the flow of deoxygenated nitrogen. It is easy to operate, has good stability, and high measurement accuracy.

[0027] The three-electrode electrochemical measurement system of the two-stage measuring cells in this invention operates under deoxygenation conditions, using nitrogen gas to deoxygenate the entire system. When nitrogen flows through the deoxygenation pipe, it generates resistance, causing a pressure difference between the two measuring cells. This pressure difference leads to the semi-fluid electrolyte in the salt bridge flowing between the two cells, potentially blowing out all the electrolyte from the salt bridge and creating a nitrogen gas path, disrupting the electrochemical measurement circuit and causing measurement failure. This invention addresses this by measuring the pressure difference between the two measuring cells and adjusting their height. The difference in liquid level between the cells balances the resistance generated by the nitrogen flow through the deoxygenation pipe, ensuring the pressure between the two cells remains balanced and guaranteeing smooth electrochemical measurement. Attached Figure Description

[0028] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of the invention in any way. Furthermore, the shapes and proportions of the components in the drawings are merely schematic to aid in understanding the invention and do not specifically limit the shapes and proportions of the components. In the drawings:

[0029] Figure 1 This is a schematic diagram of an electrochemical measurement device for pressure self-balancing deoxygenation conditions provided in an embodiment of the present invention.

[0030] In the diagram, 1. Primary deoxygenation tube, 2. Auxiliary electrode, 3. Working electrode, 4. Secondary deoxygenation tube, 5. Salt bridge switch valve, 6. Salt bridge, 7. Reference electrode, 8. Tertiary deoxygenation tube, 9. Oxygen electrode, 10. Quaternary deoxygenation tube, 11. Quaternary deoxygenation tube switch valve, 12. Primary measuring cell, 13. Secondary measuring cell, 14. Oxygen content measuring cell, 15. Water seal tank, 16. Oxygen content measuring instrument, 17. Differential pressure transmitter, 18. Primary measuring cell pressure tube, 19. Secondary measuring cell pressure tube, 20. Electrochemical workstation, 21. PLC level controller, 22. Stepper motor, 23. Lifting platform. Detailed Implementation

[0031] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0032] It should be noted that when an element is referred to as being "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only embodiments.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0034] In this invention, unless otherwise stated, directional terms such as "up," "down," "left," and "right" generally refer to the up, down, left, and right directions indicated by reference to the accompanying drawings.

[0035] Terminology Explanation:

[0036] The three-electrode system referred to in this invention consists of a working electrode, an auxiliary electrode, and a reference electrode. The working electrode is where the responding substance reacts, thereby generating a current signal; the auxiliary electrode and the working electrode form a battery, creating a circuit, and its electrochemical properties do not affect the behavior of the working electrode; the reference electrode is used to control the potential of the working electrode.

[0037] The purpose of this invention is to provide an electrochemical measurement device and method for pressure self-balancing deoxygenation conditions, which is the most effective electrochemical measurement method for measuring the corrosion law of metals under oxygen-free conditions. It utilizes the flow of high-purity nitrogen to deoxygenate the measuring device and uses a control system to automatically control the liquid level difference of the measuring device to balance the pressure difference generated by the flow of nitrogen. It is easy to operate, has good stability, and high measurement accuracy.

[0038] like Figure 1 As shown, the first objective of this invention is to provide an electrochemical measuring device for pressure self-balancing deoxygenation, including a differential pressure transmitter 17, a PLC level controller 21, an oxygen content measuring instrument 16, a primary measuring cell 12, a secondary measuring cell 13, an oxygen content measuring cell 14, and a water seal cell 15.

[0039] The primary measuring cell 12, the secondary measuring cell 13, the oxygen content measuring cell 14, and the water seal cell 15 are connected sequentially via a deoxygenation pipeline; the primary measuring cell 12 is equipped with an auxiliary electrode 2 and a working electrode 3, and the secondary measuring cell 13 is equipped with a reference electrode 7. The auxiliary electrode 2, the working electrode 3, and the reference electrode 7 are all electrically connected to the electrochemical workstation 20, forming a three-electrode measuring system; a salt bridge 6 is also provided between the primary measuring cell 12 and the secondary measuring cell 13.

[0040] The secondary measuring cell 13 is mounted on the lifting device, and the secondary measuring cell 13 forms a height difference h with the primary measuring cell 12; the differential pressure transmitter 17 tests the liquid pressure in the primary measuring cell 12 and the secondary measuring cell 13 respectively; an oxygen electrode 9 is mounted on the oxygen content measuring cell 14; the oxygen electrode 9 is electrically connected to the oxygen content measuring instrument 16; the lifting device and the differential pressure transmitter 17 are both electrically connected to the PLC level controller 21.

[0041] To reduce the influence of electrolytes within the reference electrode, this experimental setup incorporates two-stage measurement cells. The reference electrode is installed in the latter stage measurement cell, and a salt bridge is installed between the two stages to balance the anions and cations in both cells. This prevents the salt bridge solution within the reference electrode from leaking into the test solution at the liquid junction, thus interfering with the measurement, and also prevents harmful ions in the test solution from diffusing into the salt bridge solution within the reference electrode and affecting its electrode potential.

[0042] In order to accurately measure the corrosion pattern of metals under oxygen-free conditions, this invention designs an oxygen removal system that ensures that the working electrode, reference electrode, and auxiliary electrode are all under oxygen-free conditions before and during the test.

[0043] The three-electrode electrochemical measurement system with two-stage measuring cells operates under deoxygenation conditions, using nitrogen gas to deoxygenate the entire system. The nitrogen flow through the deoxygenation pipe creates resistance, resulting in a pressure difference between the two measuring cells. This pressure difference causes the semi-fluid electrolyte in the salt bridge to flow between the two cells, potentially blowing out all the electrolyte and creating a nitrogen path, disrupting the electrochemical measurement circuit and leading to measurement failure. This invention addresses this by measuring the pressure difference between the two measuring cells and adjusting their height. The difference in liquid level between the cells balances the resistance generated by the nitrogen flow through the deoxygenation pipe, ensuring the pressure between the two cells remains balanced and guaranteeing smooth electrochemical measurements.

[0044] To ensure measurement accuracy, this measuring device employs a three-electrode system for electrochemical measurements, primarily consisting of a working electrode, an auxiliary electrode, and a reference electrode. The working electrode, also known as the research electrode or experimental electrode, is used to determine the electrochemical reactions, adsorption, polarization, and other interfacial reactions. Since there is currently no reliable method to determine the absolute value of a single electrode potential, a reference electrode can be used as a reference standard to measure the relative value of the electrode potential of any electrode; this reference standard electrode is called the reference electrode. Different reference electrodes will yield different electrode potentials. The auxiliary electrode, also known as the counter electrode, is used to pass current and polarize the working electrode. The auxiliary electrode must not affect the working electrode. The three-electrode electrochemical measurement circuit consists of a primary measuring cell 12, a salt bridge switch valve 5, a salt bridge 6, a secondary measuring cell 13, an auxiliary electrode 2, a working electrode 3, a reference electrode 7, and an electrochemical workstation 20.

[0045] In this embodiment of the invention, the deoxygenation pipeline includes a primary deoxygenation pipe 1, a secondary deoxygenation pipe 4, a tertiary deoxygenation pipe 8, and a quaternary deoxygenation pipe 10; the primary measuring tank 12 is provided with the primary deoxygenation pipe 1, one end of which is connected to a nitrogen pipeline, and the other end is placed in the primary measuring tank 12. The primary measuring tank 12 and the secondary measuring tank 13 are connected through the secondary deoxygenation pipe 4, the secondary measuring tank 13 and the oxygen content measuring tank 14 are connected through the tertiary deoxygenation pipe 8, and the oxygen content measuring tank 14 is connected to the water seal tank 15 through the quaternary deoxygenation pipe 10.

[0046] The lifting device includes a stepper motor 22 and a lifting platform 23. The stepper motor 22 drives the lifting platform 23 to rise and fall. The secondary measuring tank 13 is set on the lifting platform 23. The stepper motor 22 is electrically connected to the PLC level controller 21.

[0047] To reduce the influence of electrolytes within the reference electrode, this experimental setup includes a primary measuring cell 12 and a secondary measuring cell 13. The reference electrode 7 is installed in the secondary measuring cell 13, and a salt bridge 6 is installed between the two measuring cells to balance the anions and cations in the two measuring cells. This prevents the salt bridge solution within the reference electrode from leaking from the liquid junction into the measuring solution and interfering with the measurement, and also prevents harmful ions in the measuring solution from diffusing into the salt bridge solution within the reference electrode and affecting its electrode potential.

[0048] A salt bridge switch valve 5 is installed on the salt bridge 6. The end of the deoxygenation pipeline is placed below the liquid surface to ensure good sealing. The differential pressure transmitter 17 is connected to the primary measuring cell 12 and the secondary measuring cell 13 through the primary measuring cell pressure pipe 18 and the secondary measuring cell pressure pipe 19, respectively.

[0049] The principle of this system is as follows: high-purity nitrogen gas is introduced through the primary deoxygenation pipe 1, flowing through the primary measuring cell 12, the secondary deoxygenation pipe 4, the secondary measuring cell 13, the tertiary deoxygenation pipe 8, the oxygen content measuring cell 14, the quaternary deoxygenation pipe 10, the quaternary deoxygenation pipe switch valve 11, and the water seal tank 15 to deoxygenate the entire measuring system. An oxygen electrode 9 is installed in the oxygen content measuring cell 14, and an oxygen content measuring instrument 16 is used to measure the oxygen concentration in the oxygen content measuring cell 14, thereby ensuring that the oxygen content of the entire measuring system meets the measurement requirements. At the very beginning of the measuring system... High-purity nitrogen is introduced at the end, with the highest pressure. It flows through the first-stage measuring cell 12, the second-stage deoxygenation pipe 4, the second-stage measuring cell 13, the oxygen content measuring cell 14, and the water seal cell 15 before being discharged into the atmosphere with the lowest pressure. All gases flow unidirectionally within the measuring system. As long as there is residual oxygen in the system, it will diffuse into the gas phase and flow unidirectionally with the nitrogen to the oxygen content measuring cell 14. Therefore, the oxygen content in the oxygen content measuring cell 14 can reflect the true oxygen content of the entire measuring system, eliminating the need to set up an oxygen content measuring system in each measuring cell.

[0050] The differential pressure system consists of a differential pressure transmitter 17, a primary measuring cell pressure tube 18, a secondary measuring cell pressure tube 19, a PLC level controller 21, a stepper motor 22, and a lifting platform 23.

[0051] When deoxygenated nitrogen flows in the secondary deoxygenation pipe 4, the resistance of the fluid in the pipe is the sum of the straight pipe resistance and the local resistance, which can be calculated using the Fanning equation:

[0052]

[0053] Where: λ—friction coefficient, dimensionless;

[0054] L—Pipe length, in meters;

[0055] d—pipe inner diameter, in meters;

[0056] u—fluid velocity, m / s;

[0057] ρ—Liquid density, kg / m³ 3 .

[0058] It can be seen that when the flow velocity u of the deoxygenated nitrogen increases, the flow resistance increases, which causes the pressure in the first-stage measuring cell 12 to increase. This causes the semi-fluid electrolyte in the salt bridge to flow from the first-stage measuring cell 12 to the second-stage measuring cell 13. In severe cases, it will blow out all the electrolyte in the salt bridge, forming a nitrogen passage after venting, which will destroy the electrochemical measuring circuit and lead to measurement failure.

[0059] If there is a height difference h between the solution levels measured in the primary measuring cell 12 and the secondary measuring cell 13, the static pressure difference between the two ends of the primary measuring cell 12 and the secondary measuring cell 13 is:

[0060] △P=ρgh

[0061] When the flow resistance of deoxygenated nitrogen gas is ΔP f When the static pressure difference ΔP between the primary measuring cell 12 and the secondary measuring cell 13 is greater than the static pressure difference ΔP, the electrolyte in the salt bridge diffuses and flows from the primary measuring cell 12 to the secondary measuring cell 13. In severe cases, it will blow out all the electrolyte in the salt bridge, forming a nitrogen passage after venting, which will destroy the electrochemical measurement circuit and lead to measurement failure.

[0062] When the flow resistance of deoxygenated nitrogen gas is ΔP f When the static pressure difference ΔP between the two ends of the primary measuring cell 12 and the secondary measuring cell 13 is less than that between the primary measuring cell 12 and the secondary measuring cell 13, the electrolyte in the salt bridge diffuses and flows from the secondary measuring cell 13 to the primary measuring cell 12. The impurity ions in the electrolyte affect the ion composition of the electrolyte in the primary measuring cell 12, affecting the measurement results and thus causing the measurement to fail.

[0063] For this purpose, a pressure self-balancing device was designed. The differential pressure transmitter 17 measures the pressure difference between the first-stage measuring cell 12 and the second-stage measuring cell 13 through the first-stage measuring cell pressure pipe 18 and the second-stage measuring cell pressure pipe 19. The measurement signal is transmitted to the PLC level controller 21. The PLC level controller 21 sends a control signal to the stepper motor 22 according to the liquid level fluctuation. The stepper motor 22 rotates to operate the lifting platform 23 to rise and fall.

[0064] When the pressure difference between the primary measuring tank 12 and the secondary measuring tank 13 increases, the PLC level controller 21 controls the lifting platform 23 to rise, and the liquid level difference between the primary measuring tank 12 and the secondary measuring tank 13 increases. The liquid level difference balances the pressure difference generated by the nitrogen gas flow through the secondary deoxygenation pipe 4, thereby achieving pressure balance between the primary measuring tank 12 and the secondary measuring tank 13.

[0065] When the pressure difference between the primary measuring tank 12 and the secondary measuring tank 13 decreases, the PLC level controller 21 controls the lifting platform 23 to descend, and the liquid level difference between the primary measuring tank 12 and the secondary measuring tank 13 decreases. The liquid level difference balances the pressure difference generated by the nitrogen gas flow through the secondary deoxygenation pipe 4, thereby achieving pressure balance between the primary measuring tank 12 and the secondary measuring tank 13.

[0066] To ensure reliable connections between the measuring tanks during the lifting of the platform, all deaeration pipes and pressure measuring pipes are connected using flexible rubber hoses.

[0067] A water seal pool 15 is installed at the very end of the measurement system to prevent oxygen from diffusing back into the measurement system from the atmosphere when nitrogen is introduced for deoxygenation; or to prevent oxygen from leaking back into the measurement system when the fourth-stage deoxygenation pipe switch valve 11 is closed and the system is measuring.

[0068] The present invention will now be described in detail with reference to specific embodiments and accompanying drawings.

[0069] This embodiment provides a method for using an electrochemical measuring device under pressure self-balancing deoxygenation conditions, specifically including: a primary deoxygenation tube 1, an auxiliary electrode 2, a working electrode 3, a secondary deoxygenation tube 4, a salt bridge switch valve 5, a salt bridge 6, a reference electrode 7, a tertiary deoxygenation tube 8, an oxygen electrode 9, a quaternary deoxygenation tube 10, a quaternary deoxygenation tube switch valve 11, a primary measuring cell 12, a secondary measuring cell 13, an oxygen content measuring cell 14, a water seal tank 15, an oxygen content measuring instrument 16, a differential pressure transmitter 17, a pressure tube in the primary measuring cell 18, a pressure tube in the secondary measuring cell 19, an electrochemical workstation 20, a PLC level controller 21, a stepper motor 22, and a lifting platform 23.

[0070] All deaerator pipes and pressure measuring pipes are connected using flexible rubber hoses to ensure a reliable connection between the measuring tanks when the lifting platform is raised and lowered.

[0071] The work process includes the following steps:

[0072] Step 1: Set up the measurement system;

[0073] Add working electrolyte to primary measuring cell 12. Insert auxiliary electrode 2, working electrode 3, primary deoxygenation tube 1, secondary deoxygenation tube 4 inlet end, salt bridge 6 inlet end, and primary measuring cell pressure tube 18 into the stopper of primary measuring cell 12. Insert the stopper along with the above accessories into the bottle mouth of primary measuring cell 12 and press it until it is reliably sealed.

[0074] A semi-fluid salt bridge electrolyte is added to salt bridge 6;

[0075] Add working electrolyte to the secondary measuring cell 13. Insert the reference electrode 7, the salt bridge 6 outlet end, the secondary deoxygenation tube 4 outlet end, the secondary measuring cell pressure tube 19, and the tertiary deoxygenation tube 8 into the stopper of the secondary measuring cell 13. Insert the stopper along with the above accessories into the mouth of the primary measuring cell 12 and press it until it is reliably sealed.

[0076] Add secondary demineralized water to oxygen content measuring cell 14. Insert the outlet end of the tertiary deoxygenation tube 8, the oxygen electrode 9, and the inlet end of the quaternary deoxygenation tube 10 into the stopper of oxygen content measuring cell 14. Insert the stopper along with the above accessories into the mouth of the primary measuring cell 12 and press it until it is reliably sealed.

[0077] Add secondary demineralized water to water seal tank 15, and insert the outlet end of the fourth-stage deoxygenation pipe 10 below the water level of secondary demineralized water in water seal tank 15 to prevent oxygen from diffusing and flowing back.

[0078] Connect the auxiliary electrode 2, working electrode 3, and reference electrode 7 to the corresponding interfaces of the electrochemical workstation 20 using flexible wires;

[0079] A flexible, pressure-resistant rubber tube connects the pressure tube 18 of the primary measuring cell and the pressure tube 19 of the secondary measuring cell to the pressure measurement interface of the differential pressure transmitter 17.

[0080] The differential pressure transmitter measurement signal is transmitted to the PLC level controller 21 using a signal control cable;

[0081] The control signal is transmitted from the PLC level controller 21 to the stepper motor 22 using a signal control cable;

[0082] Step 2, Tightness Test:

[0083] Close the salt bridge switch valve 5 and the fourth-stage deoxygenation pipe switch valve 11. Introduce high-purity nitrogen into the measurement system to maintain a slight positive pressure. Apply soap solution to the bottle mouth seals of the first-stage measurement cell 12, the second-stage measurement cell 13, and the oxygen content measurement cell 14, as well as to the contact points of all accessories and bottle stoppers. Observe the condition of the bottle mouth seals, accessories, and bottle stopper contact points. If soap bubbles appear, it indicates a leak. Press the bottle stopper and all connecting accessories until no soap bubbles appear.

[0084] Step 3: Deoxygenate the measurement system;

[0085] Turn on the power switches of differential pressure transmitter measuring 17, PLC level controller 21, and stepper motor 22. The pressure self-balancing system is put into operation. At this time, the gas in the system is in a non-flowing state, the resistance of the fluid in the pipeline is zero, and the height difference between the liquid levels of the two measuring tanks should also be zero. Calibrate the differential pressure transmitter measurement value to zero and calibrate the height of the lifting platform 23 to make the height difference between the liquid levels of the two measuring tanks zero.

[0086] Open the fourth-stage deoxygenation pipe switch valve 11, and the measurement system starts deoxygenation. The differential pressure transmitter 17 monitors the pressure difference between the first-stage measurement cell 12 and the second-stage measurement cell 13.

[0087] When the pressure difference between the primary measuring tank 12 and the secondary measuring tank 13 increases, the PLC level controller 21 controls the lifting platform 23 to rise, and the liquid level difference between the primary measuring tank 12 and the secondary measuring tank 13 increases. The liquid level difference balances the pressure difference generated by the nitrogen gas flow through the secondary deoxygenation pipe 4, thereby achieving pressure balance between the primary measuring tank 12 and the secondary measuring tank 13.

[0088] When the pressure difference between the primary measuring tank 12 and the secondary measuring tank 13 decreases, the PLC level controller 21 controls the lifting platform 23 to descend, and the liquid level difference between the primary measuring tank 12 and the secondary measuring tank 13 decreases. The liquid level difference balances the pressure difference generated by the nitrogen gas flow through the secondary deoxygenation pipe 4, thereby achieving pressure balance between the primary measuring tank 12 and the secondary measuring tank 13.

[0089] In oxygen content measuring tank 14, the oxygen content of the demineralized water is measured. Since high-purity nitrogen is introduced at the very front of the measuring system, where the pressure is highest, and the gas flows through primary measuring tank 12, secondary deoxygenation pipe 4, secondary measuring tank 13, oxygen content measuring tank 14, and water seal tank 15 before being discharged into the atmosphere at the lowest pressure, all gases flow unidirectionally within the measuring system. As long as there is residual oxygen in the system, it will diffuse into the gas phase and flow unidirectionally with the nitrogen to oxygen content measuring tank 14. Therefore, the oxygen content in oxygen content measuring tank 14 can reflect the true oxygen content of the entire measuring system, eliminating the need to set up an oxygen content measuring system in each measuring tank.

[0090] Observe the oxygen concentration value in the oxygen content measuring instrument 16, and adjust the opening of the fourth-stage deoxygenation pipe switch valve 11 according to the trend of oxygen concentration change, thereby adjusting the flow rate of deoxygenated nitrogen. At this time, the resistance of nitrogen flow through the deoxygenation pipe changes, and the pressure difference between the first-stage measuring tank 12 and the second-stage measuring tank 13 changes. The PLC level controller 21 controls the lifting platform 23 to rise and fall, and the liquid level difference between the first-stage measuring tank 12 and the second-stage measuring tank 13 changes. The liquid level difference balances the pressure difference generated by the nitrogen flow through the second-stage deoxygenation pipe 4, and continuously achieves pressure balance between the first-stage measuring tank 12 and the second-stage measuring tank 13.

[0091] During the deoxygenation process, the level of demineralized water in the water seal tank 15 should be monitored at all times. When the level drops, demineralized water should be added in time to prevent leakage from the outlet of the fourth-stage deoxygenation pipe 10 above the screen and oxygen leakage back to the measurement system.

[0092] Step 4: Electrochemical Measurement;

[0093] When the oxygen content reaches the measurement requirement, open the salt bridge switch valve 5 and use the auxiliary electrode 2, working electrode 3, and reference electrode 7 to perform electrochemical measurement at the electrochemical workstation 20.

[0094] During the measurement process, the differential pressure transmitter 17 continuously observes the pressure difference between the primary measuring cell 12 and the secondary measuring cell 13, and feeds it back to the PLC level controller 21 to control the lifting platform 23 to rise and fall. The change in the liquid level difference between the primary measuring cell 12 and the secondary measuring cell 13 balances the pressure difference generated by the nitrogen gas flow through the secondary deoxygenation pipe 4, and continuously achieves pressure balance between the primary measuring cell 12 and the secondary measuring cell 13. This prevents the internal salt bridge solution of the reference electrode from leaking from both ends of the salt bridge into the measuring solution under the action of pressure difference, thus interfering with the measurement.

[0095] If necessary, the fourth-stage deoxygenation pipe switch valve 11 can be closed, and the deoxygenated nitrogen flow rate will be zero, facilitating electrochemical testing. At this time, the gas in the system is in a non-flowing state, the resistance of the fluid in the pipeline is zero, and the height difference between the liquid levels in the two-stage measuring cells should also be zero.

[0096] If the oxygen concentration value observed in the oxygen content measuring instrument 16 changes and does not meet the measurement requirements, it indicates that there is a leak in the measuring system. Reopen the fourth-stage deoxygenation pipe switch valve 11 and perform the deoxygenation procedure until the requirements are met.

[0097] It should be noted that in the description of this invention, the terms "first," "second," etc., are used only for descriptive purposes and to distinguish similar objects; there is no order between them, nor should they be construed as indicating or implying relative importance. Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0098] It should be understood that the above description is for illustrative purposes and not for limitation. Many embodiments and applications beyond the provided examples will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of this teaching should not be determined by reference to the above description, but rather by reference to the foregoing claims and the full scope of their equivalents. For purposes of completeness, all articles and references, including patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the foregoing claims is not intended as a waiver of that subject matter, nor should it be construed as an indication that the applicant has not considered that subject matter as part of the disclosed inventive subject matter.

Claims

1. An electrochemical measuring device for pressure self-balancing deoxygenation operation, characterized in that: It includes a differential pressure transmitter (17), a PLC level controller (21), an oxygen content measuring instrument (16), a primary measuring cell (12), a secondary measuring cell (13), an oxygen content measuring cell (14), and a water seal cell (15). The primary measuring tank (12), the secondary measuring tank (13), the oxygen content measuring tank (14), and the water seal tank (15) are connected in sequence through a deoxygenation pipeline; The primary measuring cell (12) is equipped with an auxiliary electrode (2) and a working electrode (3), and the secondary measuring cell (13) is equipped with a reference electrode (7). The auxiliary electrode (2), the working electrode (3) and the reference electrode (7) are all electrically connected to the electrochemical workstation (20) to form a three-electrode measuring system. A salt bridge (6) is also provided between the primary measuring cell (12) and the secondary measuring cell (13). The secondary measuring pool (13) is mounted on the lifting device, and the secondary measuring pool (13) and the primary measuring pool (12) form a height difference h; The differential pressure transmitter (17) tests the liquid pressure in the first-stage measuring cell (12) and the second-stage measuring cell (13) respectively; an oxygen electrode (9) is provided on the oxygen content measuring cell (14); the oxygen electrode (9) is electrically connected to the oxygen content measuring instrument (16); the lifting device and the differential pressure transmitter (17) are both electrically connected to the PLC level controller (21); The deoxygenation pipeline includes a primary deoxygenation pipe (1), a secondary deoxygenation pipe (4), a tertiary deoxygenation pipe (8), and a quaternary deoxygenation pipe (10). The primary measuring tank (12) is equipped with a primary deoxygenation pipe (1). One end of the primary deoxygenation pipe (1) is connected to a nitrogen pipeline, and the other end is placed in the primary measuring tank (12). The primary measuring tank (12) is connected to the secondary measuring tank (13) through the secondary deoxygenation pipe (4). The secondary measuring tank (13) is connected to the oxygen content measuring tank (14) through the tertiary deoxygenation pipe (8). The oxygen content measuring tank (14) is connected to the water seal tank (15) through the quaternary deoxygenation pipe (10). The lifting device includes a stepper motor (22) and a lifting platform (23). The stepper motor (22) drives the lifting platform (23) to lift. The secondary measuring pool (13) is installed on the lifting platform (23). The stepper motor (22) is electrically connected to the PLC level controller (21). The differential pressure transmitter (17) is connected to the first-level measuring cell (12) and the second-level measuring cell (13) through the first-level measuring cell pressure tube (18) and the second-level measuring cell pressure tube (19), respectively.

2. The electrochemical measuring device for pressure self-balancing deoxygenation as described in claim 1, characterized in that: A salt bridge switch valve (5) is provided on the salt bridge (6).

3. The electrochemical measuring device for pressure self-balancing deoxygenation as described in claim 1, characterized in that: The end of the deoxygenation pipe is positioned below the liquid surface.

4. The measurement method of the electrochemical measuring device under pressure self-balancing deoxygenation conditions according to any one of claims 1 to 3, characterized in that, include: Nitrogen gas flows through the primary measuring cell (12), the secondary measuring cell (13), the oxygen content measuring cell (14), and the water seal cell (15) to deoxygenate the entire measuring system; Use an oxygen content measuring instrument (16) to measure the oxygen concentration in the oxygen content measuring cell (14) to ensure that the oxygen content of the entire measuring system meets the test requirements; The differential pressure transmitter (17) measures the pressure difference between the primary measuring cell (12) and the secondary measuring cell (13), and transmits the measurement signal to the PLC level controller (21). The PLC level controller (21) sends a control signal to the lifting device according to the liquid level fluctuation. The lifting device adjusts the height difference h between the secondary measuring cell (13) and the primary measuring cell (12) to achieve pressure balance.

5. The measurement method of the electrochemical measuring device under pressure self-balancing deoxygenation conditions according to claim 4, characterized in that, The lifting device adjusts the height difference h between the secondary measuring tank (13) and the primary measuring tank (12) to achieve pressure balance, including: By measuring the pressure difference between the two measuring tanks and adjusting the height between them, the resistance generated when nitrogen flows through the deoxygenation pipe is balanced by utilizing the liquid level difference between the measuring tanks, and the pressure between the two measuring tanks is always in a balanced state.

6. The measurement method of the electrochemical measuring device under pressure self-balancing deoxygenation conditions according to claim 4, characterized in that, The lifting device adjusts the height difference h between the secondary measuring pool (13) and the primary measuring pool (12) to achieve pressure balance, specifically including: When the pressure difference between the primary measuring tank (12) and the secondary measuring tank (13) increases, the PLC level controller (21) controls the lifting platform (23) to rise, and the liquid level difference between the primary measuring tank (12) and the secondary measuring tank (13) increases. The liquid level difference balances the pressure difference generated by the nitrogen gas flow through the secondary deoxygenation pipe (4), so that the pressure between the primary measuring tank (12) and the secondary measuring tank (13) is balanced. When the pressure difference between the primary measuring tank (12) and the secondary measuring tank (13) decreases, the PLC level controller (21) controls the lifting platform (23) to descend, and the liquid level difference between the primary measuring tank (12) and the secondary measuring tank (13) decreases. The liquid level difference balances the pressure difference generated by the nitrogen gas flow through the secondary deoxygenation pipe (4), so that the pressure between the primary measuring tank (12) and the secondary measuring tank (13) is balanced.

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