In-situ electrochemical corrosion test method for chlor-alkali service simulation

Abstract

The application discloses a kind of in-situ electrochemical corrosion test methods for chlor-alkali working condition simulation, belong to corrosion simulation experimental technical field.The method includes: three-electrode system including working electrode, reference electrode and counter electrode are sealedly installed in the kettle cover of experimental device, gas phase valve, liquid phase valve and sensor group are communicated with experimental space;Open liquid phase valve and introduce containing alkali corrosion medium;Open gas phase valve, replace air or form preset atmosphere;In closed state, heating and pressure adjustment are carried out to experimental device, form preset temperature or preset pressure simulation environment;The corrosion potential, corrosion current density and impedance parameters of the material to be measured are collected in-situ by three-electrode system.Experimental device includes reactor body, kettle cover and simulation part of integrated gas phase valve, liquid phase valve, heating furnace and sensor group.The method can simultaneously control the concentration of strong alkali, impurity ion, atmosphere, temperature, pressure and medium flow state, improve the accuracy and data reliability of chlor-alkali industry corrosion working condition simulation.

Description

Technical Field

[0001] This application relates to the field of corrosion simulation experimental technology, and in particular to an in-situ electrochemical corrosion testing method for chlor-alkali working condition simulation. Background Technology

[0002] In the evaporation and solidification process of the chlor-alkali industry, the operating medium is usually a high-temperature, high-concentration alkaline solution, which may also contain impurities such as fluoride ions, chloride ions, and sulfate ions, or ions introduced during the process. These highly alkaline media and corrosive ions can cause pipelines, valves, and related equipment to face long-term corrosion risks, leading to equipment corrosion and leaks, unplanned shutdowns for maintenance, and safety accidents.

[0003] To prevent corrosion and leakage accidents in the chlor-alkali industry from the root, it is necessary to systematically conduct corrosion experiments that conform to actual working conditions, and combine electrochemical testing methods to deeply reveal the material corrosion patterns and failure mechanisms of pipelines and related equipment.

[0004] However, existing corrosion testing methods are mostly designed for strong alkaline conditions, normal pressure conditions, or immersion conditions, and it is difficult to simultaneously simulate high temperature strong alkali, multiple ions, controllable atmosphere, temperature-pressure coupling, and medium flow state. At the same time, ordinary electrochemical cells are difficult to conduct in-situ testing in a closed high temperature strong alkaline environment, resulting in deviations between the test results and the actual working conditions. Summary of the Invention

[0005] This application provides an in-situ electrochemical corrosion testing method for chlor-alkali working condition simulation, in order to solve the following technical problem: how to achieve controllable simulation and in-situ electrochemical testing of the corrosion process in the chlor-alkali industry under high temperature, strong alkali, multi-ion, controllable atmosphere and gas-liquid coupling conditions.

[0006] In a first aspect, embodiments of this application provide an in-situ electrochemical corrosion testing method for simulating chlor-alkali operating conditions, used to simulate the corrosion process in the chlor-alkali industry, the testing method comprising: A three-electrode system, including a working electrode, a reference electrode, and a counter electrode, is sealed and installed in the lid of the experimental apparatus, so that the test surface of the working electrode is exposed in the experimental space of the experimental apparatus, and the gas phase valve, liquid phase valve, and sensor group are connected to the experimental space. The liquid phase valve is opened to introduce an alkaline corrosive medium into the experimental space; the gas phase valve is opened to replace the air in the experimental space or to form a preset atmosphere. The experimental device is heated and the pressure is adjusted in a closed state to bring the alkaline corrosive medium to a preset temperature or preset pressure, and to bring the alkaline corrosive medium into contact with the test surface of the working electrode to form a simulated environment. The electrochemical response process of the working electrode is collected in situ using the three-electrode system to obtain the corrosion potential, corrosion current density, and impedance parameters of the material under test in the alkaline corrosive medium, thereby completing the in-situ electrochemical corrosion test; wherein, the electrochemical response includes at least one of open circuit potential, polarization curve, and electrochemical impedance spectroscopy; The experimental apparatus includes: The reactor body and the reactor lid, wherein the reactor lid abuts against the reactor body to form the experimental space of the experimental apparatus; The simulation unit includes the gas phase valve, the liquid phase valve, the heating furnace, and the sensor group. The reactor body is inserted into the heating furnace. The gas phase valve, the liquid phase valve, and the sensor group are all inserted into the reactor lid, and the sensing end of the sensor group is inserted into the reactor body through the reactor lid.

[0007] Optionally, the mass fraction of alkaline substances in the alkaline corrosive medium is 10% to 50%, and the alkaline corrosive medium contains Cl. - F - SO4 2- At least one impurity ion in it.

[0008] Optionally, the preset temperature is 80℃~250℃; the preset pressure is 0.1MPa~12.5MPa.

[0009] Optionally, the three-electrode system includes a reference electrode, a counter electrode, and a working electrode, with the counter electrode and the working electrode arranged opposite to each other. The reference electrode, the counter electrode, and the working electrode pass through the vessel lid and extend into the reactor body; the exposed area of ​​the test surface of the working electrode is 0.1 cm². 2 ~5cm 2 .

[0010] Optionally, the test surface of the working electrode is positioned directly opposite the erosion surface of the alkaline corrosive medium, or The test surface of the working electrode is located within the flow path region of the alkaline corrosive medium.

[0011] Optionally, the inner surface of the reactor body is covered with an inert layer, the inert layer comprising at least one of PTFE, PFA, FEP, and ceramic coating, and the thickness of the inert layer is 1 mm to 3 mm.

[0012] Optionally, the experimental apparatus further includes a fastening unit disposed between the reaction vessel body and the vessel lid.

[0013] Optionally, the fastening unit includes a first fastening clamp, a second fastening clamp, a fastening block, a fastening groove, a fastening bolt, and a fastening bolt knob. One end of the first fastening clamp is hinged to one end of the second fastening clamp. The fastening block is disposed in the other end of the first fastening clamp. The fastening groove is disposed in the other end of the second fastening clamp. One end of the fastening bolt is threadedly connected to the fastening bolt knob. The other end of the fastening bolt passes through the fastening groove and is fixedly connected to the fastening block, so that the length of the fastening bolt in the fastening groove can be adjusted by the fastening bolt knob.

[0014] Optionally, the sensor group includes a pressure sensor and a temperature sensor, which pass through the vessel lid and extend into the reactor body.

[0015] Optionally, the experimental apparatus further includes a rupture disc, which is disposed on the pressure relief channel of the vessel lid and communicates with the reactor body.

[0016] The technical solutions provided in this application have the following advantages compared with the prior art: This application provides an in-situ electrochemical corrosion testing method for simulating chlor-alkali working conditions. This method uses a gas-phase valve to replace air in the experimental space or create a preset atmosphere, and a liquid-phase valve to introduce an alkaline corrosive medium. Through heating and pressure adjustment, a high-temperature, high-pressure environment is created in the experimental space between the sealed reactor body and the reactor lid. This allows the corrosive medium inside the reactor to dynamically scour the working electrodes of the three-electrode system, simulating the real flow corrosion environment of the chlor-alkali industry and overcoming the limitations of traditional static immersion. Furthermore, the in-situ chemical reaction at the working electrodes in the three-electrode system allows for real-time and accurate acquisition of corrosion current, corrosion potential, and impedance spectrum data using the reference electrode as a potential benchmark. This dynamically captures transient behaviors such as passivation film rupture and pitting initiation, avoiding the interruption of operating conditions and data distortion inherent in traditional offline testing. In addition, the sensor array provides real-time feedback of temperature and pressure, enabling real-time control of the corrosion process under realistic extreme conditions by controlling the gas-phase valve and the heating furnace. This represents a leap from static approximate simulation to dynamic re-enactment, significantly improving the accuracy and reliability of the electrochemical corrosion test simulation. Attached Figure Description

[0017] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0018] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A flowchart of an in-situ electrochemical corrosion testing method for simulating chlor-alkali working conditions is provided in an embodiment of this application; Figure 2 This is a structural diagram of the experimental apparatus in the testing method provided in the embodiments of this application; Figure 3 A schematic diagram of the heating furnace in the experimental apparatus of the test method provided in the embodiments of this application; Figure 4 This is a schematic diagram of the three-electrode system of the experimental apparatus in the testing method provided in the embodiments of this application; Figure 5 A schematic diagram of the combination of the reaction vessel body and the vessel lid in the test method provided in the embodiments of this application; Figure 6 This is a schematic diagram of the sensor group and the rupture disc in the experimental apparatus of the testing method provided in the embodiments of this application; Figure 7 A schematic diagram of the inert layer of the experimental apparatus in the testing method provided in the embodiments of this application; Among them, 1-three-electrode system, 101-reference electrode, 102-counter electrode, 103-working electrode, 2-gas phase valve, 3-liquid phase valve, 4-reaction vessel body, 401-inert layer, 5-vessel cover, 6-heating furnace, 7-sensor group, 701-pressure sensor, 702-temperature sensor, 8-fastening unit, 801-first fastening clamp, 802-second fastening clamp, 803-fastening block, 804-fastening groove, 805-fastening bolt, 806-fastening bolt knob, 9-rupture disc. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0021] The range descriptions used in this application, such as numerical ranges and proportional ranges, include all possible sub-ranges and single numerical values ​​within that range. For example, the range descriptions of "1 to 6" or "1~6" cover all sub-ranges (such as 1 to 3, 2 to 5, etc.) and single numbers (such as 1, 2, 3, 4, 5, 6) between 1 and 6. Unless otherwise specified, the terms "comprising" and others used herein mean "including but not limited to"; relational terms such as "first" and "second" are used only to distinguish different entities or operations and do not imply an actual order or relationship; "and / or" indicates that multiple situations can exist individually or simultaneously; expressions such as "at least one," "multiple," and "at least one" refer to any combination of the corresponding objects, including combinations of single or multiple objects. The proportional relationships involved in this document, such as mass ratios and molar ratios, should be understood as the correspondence between the first and second terms of a proportional formula, according to the order of description. The raw materials, reagents, instruments, and equipment used herein can all be obtained by purchasing from the market or by existing methods.

[0022] Figure 1 An exemplary flowchart of an in-situ electrochemical corrosion testing method for simulating chlor-alkali operating conditions is shown in an embodiment of this application. Figure 2 An exemplary structural diagram of the experimental apparatus in the testing method provided in the embodiments of this application is shown; Figure 5 An exemplary schematic diagram of the combination of the reaction vessel body and the vessel lid in the testing method provided in the embodiments of this application is shown; like Figure 1 As shown in the embodiments of this application, an in-situ electrochemical corrosion testing method for simulating chlor-alkali working conditions is provided to simulate the corrosion process in the chlor-alkali industry. The testing method includes: S1. A three-electrode system 1, including a working electrode 103, a reference electrode 102, and a counter electrode 101, is sealed and installed on the lid 5 of the experimental apparatus, so that the test surface of the working electrode 103 is exposed in the experimental space of the experimental apparatus, and the gas phase valve 2, the liquid phase valve 3, and the sensor group 7 are connected to the experimental space. S2. Open the liquid phase valve 3 to introduce an alkaline corrosive medium into the experimental space; open the gas phase valve 2 to replace the air in the experimental space or to form a preset atmosphere; S3. The experimental device is heated and the pressure is adjusted in a closed state to bring the alkaline corrosive medium to a preset temperature or preset pressure, and to bring the alkaline corrosive medium into contact with the test surface of the working electrode 103 to form a simulated environment; S4. The electrochemical response process changes of the working electrode 103 are collected in situ through the three-electrode system 1 to obtain the corrosion potential, corrosion current density and impedance parameters of the material under test in the alkaline corrosive medium, so as to complete the in-situ electrochemical corrosion test; wherein, the electrochemical response includes at least one of open circuit potential, polarization curve and electrochemical impedance spectrum; like Figure 2 As shown, the experimental setup also includes: Reactor body 4 and lid 5, such as Figure 5 As shown, the lid 5 abuts against the reactor body 4 to form the experimental space of the experimental apparatus; The simulation unit includes the gas phase valve 2, the liquid phase valve 3, the heating furnace 6, and the sensor group 7. The reactor body 4 is inserted into the heating furnace 6. The gas phase valve 2, the liquid phase valve 3, and the sensor group 7 are all inserted into the reactor cover 5, and the sensing end of the sensor group 7 is set deep into the reactor body 4 through the reactor cover 5.

[0023] It should be noted that the corrosion process in the chlor-alkali industry is mainly manifested as the coupling effect of high-concentration alkaline solution and impurity ions such as chloride ions and fluoride ions on chlor-alkali related equipment under controlled atmosphere, temperature, pressure and medium flow conditions. Through the coupling effect, electrochemical corrosion reactions occur on the surfaces of pipelines, valves, evaporators or other key equipment.

[0024] It should be noted that the reactor body 4 can be composed of a vessel body, an inner lining, and a vessel opening. The vessel body and lid 5 can be made of 316L stainless steel. In corrosive environments characterized by high temperature, strong alkali, and the coexistence of multiple ions, the 316L stainless steel of the vessel body and lid 5 can form a stable passivation film on the surface. This passivation film effectively resists uniform corrosion from corrosive media (generally alkaline solutions). Simultaneously, the molybdenum (Mo) element contained in 316L stainless steel significantly enhances its resistance to pitting and crevice corrosion, while the low carbon content of 316L stainless steel fundamentally inhibits the tendency for intergranular corrosion in the heat-affected zone. Furthermore, 316L stainless steel maintains good mechanical properties and structural stability under high-temperature conditions, ensuring sufficient strength and safety for the vessel body and lid 5 during long-term high-pressure operation.

[0025] It should be noted that the liner or inert layer 401 can be made of corrosion-resistant materials such as polytetrafluoroethylene (PTFE), perfluoroalkyl compounds (PFA), fluorinated ethylene propylene copolymer (FEP), or ceramic coatings. Within the set temperature, pressure, and media range, the liner or inert layer 401 can isolate the corrosive medium from the metal vessel, reduce the interference of external metal ions on the electrochemical test results, and facilitate cleaning and maintenance after the experiment.

[0026] It should be noted that the vessel opening can be designed in a stepped shape, which has the following advantages: (1) Achieve a reliable pressure seal: The stepped nozzle provides a precise positioning groove for seals such as spiral wound gaskets. With the bolts between the lid 5 and the reactor body 4 tightened, the stepped nozzle allows pressure to be concentrated on the narrow contact surface of the steps, generating an extremely high sealing specific pressure. This forces the seal to deform and fill the microscopic unevenness, thereby forming a reliable sealing interface under high temperature and high pressure conditions, effectively preventing the leakage of corrosive media inside the reactor body 4.

[0027] (2) Enhance mechanical strength and pressure resistance: The stepped design of the vessel opening smoothly disperses internal pressure and bolt preload, significantly reducing stress concentration. The stepped design also enhances the overall rigidity of the area, effectively resisting deformation caused by high pressure and ensuring that the flange and vessel cover 5 maintain the correct geometry under extreme conditions. This improves the overall pressure resistance and safety of the reactor body 4 and vessel cover 5.

[0028] (3) Facilitates centering and installation: The stepped vessel opening itself serves a positioning function. The stepped opening has multiple steps; the outer steps facilitate initial guidance, while the inner steps ensure easy and precise alignment of the bolt holes on the flange between the vessel cover 5 and the reactor body 4. This simplifies the installation process of the vessel cover 5 and ensures the seals are in the optimal working position.

[0029] It should be noted that the vessel cover 5 can be provided with multiple through holes, which are divided into working holes and spare holes according to their functions. The working holes are channels for the three-electrode system 1, gas phase valve 2, liquid phase valve 3 and various sensors to enter the liner. The spare holes are generally idle and the reactor body 4 is sealed by tightening the bolts.

[0030] It should be noted that the heating furnace 6 can be as follows: Figure 3 The intelligent heating furnace shown is a TLZN-10000 model furnace.

[0031] It should be noted that the in-situ electrochemical corrosion testing method for chlor-alkali industrial operation simulation provided in this application systematically improves the simulation accuracy of corrosion experiments in the chlor-alkali industry through four dimensions: high-fidelity operation condition reproduction, dynamic process simulation, online precise measurement, and environmental purity control. The specific mechanism is as follows: 1. High degree of reproduction of extreme working conditions.

[0032] Traditional corrosion tests are often limited to ambient temperature and pressure or static conditions due to the limited tolerance of equipment, resulting in significant discrepancies with the actual operating conditions of chlor-alkali industry evaporation and solidification (high temperature, high pressure, high concentration of alkali solution, and coexistence of multiple ions). This test method achieves high-fidelity simulation through the following design: (1) High temperature and high pressure environment: The reactor with 316L stainless steel body and PTFE lining is resistant to strong alkali and various corrosive ions. Combined with intelligent heating furnace 6, the temperature can be precisely controlled at the target working condition (e.g., 150℃, 50% NaOH evaporation and concentration section), and the corresponding saturated vapor pressure is naturally established through the closed space. (2) Precise control of multiple corrosive ions and atmosphere: The injection of gaseous media (such as inert gas replacement, chlorine atmosphere simulation) and liquid media (high-concentration alkaline solution and solution containing fluoride or chloride ions) is controlled by gas phase valve 2 and liquid phase valve 3 respectively, so as to accurately reproduce the complex media environment in actual production. (3) Flow scouring simulation: During the heating and pressurization process, the working end face of the three-electrode system 1 is actively scouring by a high-concentration alkaline corrosive medium to simulate the dynamic flow corrosion of the alkaline corrosive medium in the pipeline, rather than the traditional static immersion, which more realistically reflects the service status of the material in the actual pipeline.

[0033] 2. The completeness of online electrochemical testing.

[0034] Commercially available corrosion testing equipment is often incompatible with electrochemical testing under extreme conditions, making it impossible to obtain corrosion kinetic data in real time. This testing method directly integrates three electrodes (working electrode 103, reference electrode 101, and counter electrode 102) into the reactor lid 5, achieving: (1) In-situ real-time measurement: Under the condition of maintaining the preset temperature, pressure and atmosphere without interruption, directly connect to the electrochemical workstation to obtain open circuit potential, polarization curve and electrochemical impedance spectroscopy (EIS) data online; (2) Precise potential reference: The reference electrode 101 provides a stable potential reference in extreme environments, ensuring the accuracy and reproducibility of data such as polarization curves, and avoiding data distortion caused by operating condition fluctuations or circuit interference; (3) Dynamic process capture: Continuous recording of electrochemical information distribution can analyze transient behaviors such as passivation film rupture, pitting corrosion initiation, and side reaction occurrence during the corrosion process, rather than just obtaining static weight loss results before and after the experiment.

[0035] 3. Environmental purity and interference control.

[0036] The purity of the experimental medium directly affects the accuracy of corrosion mechanism studies. This testing method eliminates external interference through multiple design steps: (1) Inert inner lining isolation: The inert layer on the inner wall of the reactor body 4 can effectively isolate the 316L stainless steel metal reactor body from direct contact with the corrosive medium, prevent metal ions from dissolving and contaminating the high-concentration alkaline corrosive medium, ensure that the corrosion test is not interfered with by external metal ions, and maintain the environmental purity of the corrosive medium. (2) High airtightness maintenance: The stepped design of the vessel mouth structure, combined with the fastening clamp, can provide reliable axial sealing force, prevent the leakage of high temperature corrosive media, prevent the intrusion of external air or moisture, and ensure the long-term stability of the preset atmosphere (e.g., oxygen-free environment). 4. Accessibility under extreme conditions under safety barriers.

[0037] The premise of accurate simulation is safe and stable operation under real extreme conditions. This experimental device can be equipped with a rupture disc 9 structure as the final mechanical venting protection, so that the corrosion test can be carried out under conditions close to or reaching the upper limit of the actual operating pressure, without having to artificially reduce experimental parameters due to safety concerns, thus avoiding the mechanism distortion caused by reducing the conditions of traditional experimental parameters.

[0038] In summary, the embodiments of this application provide an in-situ electrochemical corrosion testing method for chlor-alkali working condition simulation. This testing method integrates the chemical factors (high concentration of strong alkali and various corrosive ions), physical factors (high temperature, high pressure, flow erosion), and electrochemical factors (in-situ potential / current response) experienced by the experimental materials in the actual chlor-alkali industry into a controllable closed experimental space. This achieves a leap from static approximate simulation to dynamic reproduction, thereby significantly improving the accuracy and data reliability of electrochemical corrosion testing simulation.

[0039] In some optional embodiments, the mass fraction of alkaline substances in the alkaline corrosive medium is 10% to 50%; and the alkaline corrosive medium contains Cl. - F - SO4 2- At least one impurity ion in it.

[0040] In these embodiments, an alkaline corrosive medium with a mass fraction of 10%–50% can cover the strongly alkaline corrosive environments commonly encountered in evaporation and concentration, alkali solution transportation, and solid alkali-related processes, while avoiding excessively high concentrations that could reduce the compatibility of experimental equipment materials. The alkaline corrosive medium contains Cl. - F - SO4 2- At least one impurity ion in it can simulate residual brine in the chlor-alkali industry or impurities in actual production.

[0041] The mass fraction of alkaline substances in the alkaline corrosive medium can be 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%.

[0042] Furthermore, the mass fraction of alkaline substances in the alkaline corrosive medium can be 32% to 50%.

[0043] It should be noted that the alkaline corrosive medium can be either NaOH solution or KOH solution.

[0044] In some optional embodiments, the preset temperature is 80℃ to 250℃; the preset pressure is 0.1MPa to 12.5MPa.

[0045] In these embodiments, the preset temperature of 80°C to 250°C and the preset pressure of 0.1MPa to 12.5MPa can keep the corrosive medium in the reactor under high temperature or high pressure, which is beneficial to simulating the extreme conditions of the chlor-alkali industry and ensuring the comprehensiveness of the test method.

[0046] The preset temperature can be 80℃, 90℃, 100℃, 110℃, 120℃, 130℃, 140℃, 150℃, 200℃ or 250℃.

[0047] The preset pressure can be 0.1MPa, 0.2MPa, 0.3MPa, 0.4MPa, 0.5MPa, 1.0MPa, 1.5MPa, 2.0MPa, 2.5MPa, 3.0MPa, 3.5MPa, 4.0MPa, 5.0MPa, 10.0MPa, or 12.5MPa.

[0048] Furthermore, the preset temperature can be 120℃ to 180℃. The preset pressure can be 0.1MPa to 5.0MPa.

[0049] Figure 4 An exemplary schematic diagram of the three-electrode system of the experimental apparatus in the testing method provided in the embodiments of this application is shown; In some alternative implementations, such as Figure 4 As shown, the three-electrode system 1 includes a reference electrode 101, a counter electrode 102, and a working electrode 103. The counter electrode 102 and the working electrode 103 are arranged opposite to each other. The reference electrode 101, the counter electrode 102, and the working electrode 103 pass through the vessel cover 5 and extend into the reaction vessel body 4. The exposed area of ​​the test surface of the working electrode 103 is 0.1 cm². 2 ~5cm 2 .

[0050] In these embodiments, a three-electrode system 1 is designed, comprising a reference electrode 101, a counter electrode 102, and a working electrode 103. The working electrode 103 (made from the metal material to be tested) simulates the material surface of the actual equipment in the corrosive medium, and a corresponding electrochemical corrosion reaction occurs within the reaction vessel 4, which is beneficial for simulating the real corrosion process. Furthermore, the reference electrode 101 provides a known, stable, and unchanging electrode potential reference that is independent of the loop current, providing a reliable reference point for the potential measurement of the working electrode 103. This allows for precise measurement and control of the working electrode 103's potential, ensuring the accuracy and reproducibility of all potential-related data (e.g., self-corrosion potential, polarization curves). Additionally, the counter electrode 102 can be an inert electrode, providing a loop channel for electron exchange by the working electrode 103, ensuring a closed current loop and guaranteeing the accuracy of the working electrode 103's measurements. Furthermore, the exposed area is 0.1 cm². 2 ~5cm 2 The test surface of the working electrode 103 allows the alkaline corrosive medium to fully contact the working electrode, which is conducive to the smooth progress of the corrosion process of the alkaline corrosive medium and ensures the accuracy and reproducibility of all potential-related data.

[0051] It should be noted that during the testing process, the working electrode 103 will generate electrochemical test signals (such as corrosion current and corrosion resistance) based on chemical reactions, which is the direct carrier of corrosion behavior inside the reactor body 4.

[0052] In some optional embodiments, the test surface of the working electrode 103 is positioned directly opposite the erosion surface of the alkaline corrosive medium, or The test surface of the working electrode 103 is located within the flow path region of the alkaline corrosive medium.

[0053] In these embodiments, the test surface of the working electrode 103 is positioned directly opposite the scouring surface of the alkaline corrosive medium, or the test surface of the working electrode 103 is placed within the flow path area of ​​the alkaline corrosive medium. This allows the alkaline corrosive medium to have maximum contact with the working electrode 103, ensuring the smooth progress of the corrosion process of the alkaline corrosive medium and ensuring the accuracy and reproducibility of all potential-related data.

[0054] Figure 7 An exemplary schematic diagram of the inert layer of the experimental apparatus in the testing method provided in the embodiments of this application is shown; In some alternative implementations, such as Figure 7 As shown, the inner surface of the reactor body 4 is covered with an inert layer 401, the thickness of which is 1mm to 3mm.

[0055] In these embodiments, an inert layer 401 can be used on the inner surface of the reactor body 4 to allow the corrosive medium to flow in the experimental space, thereby preventing the corrosive medium from directly contacting the reactor body 4 and causing metal ions to dissolve and contaminate the high-concentration alkaline solution. This ensures that the corrosion test is not interfered with by external metal ions and maintains the environmental purity of the corrosive medium.

[0056] The thickness of the inert layer 401 can be 1 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 2.0 mm, 2.5 mm or 3.0 mm.

[0057] Furthermore, the thickness of the inert layer 401 can be 1mm to 2mm.

[0058] In some alternative embodiments, the experimental apparatus further includes a fastening unit 8 disposed between the reaction vessel body 4 and the vessel cover 5.

[0059] In these embodiments, a fastening unit 8 is introduced into the experimental apparatus. The fastening unit 8 can be used to firmly fix the reaction vessel body 4 and the vessel cover 5, so as to avoid the leakage of corrosive media or the vessel cover 5 falling off and causing experimental accidents.

[0060] In some optional embodiments, the fastening unit 8 includes a first fastening clamp 801, a second fastening clamp 802, a fastening block 803, a fastening groove 804, a fastening bolt 805, and a fastening bolt 805 knob. One end of the first fastening clamp 801 is hinged to one end of the second fastening clamp 802. The fastening block 803 is disposed in the other end of the first fastening clamp 801. The fastening groove 804 is disposed in the other end of the second fastening clamp 802. One end of the fastening bolt 805 is threadedly connected to the fastening bolt 805 knob. The other end of the fastening bolt 805 passes through the fastening groove 804 and is fixedly connected to the fastening block 803, so that the length of the fastening bolt 805 in the fastening groove 804 can be adjusted by the fastening bolt 805 knob.

[0061] In these embodiments, the fastening unit 8 is designed to include a first fastening clamp 801, a second fastening clamp 802, a fastening block 803, a fastening groove 804, a fastening bolt 805, and a fastening bolt 805 knob. By hinged at one end of the first fastening clamp 801 and the second fastening clamp 802, and by adjusting the other end through the cooperation between the fastening block 803, the fastening groove 804, the fastening bolt 805, and the fastening bolt 805 knob, the other ends of the first fastening clamp 801 and the second fastening clamp 802 can be firmly abutted, ensuring a firm fixation between the reactor body 4 and the reactor cover 5.

[0062] Figure 6An exemplary schematic diagram of the sensor group and rupture disc structure of the experimental apparatus in the testing method provided in the embodiments of this application is shown; In some alternative implementations, such as Figure 6 As shown, the sensor group 7 includes a pressure sensor 701 and a temperature sensor 702. The pressure sensor 701 and the temperature sensor pass through the vessel cover 5 and extend into the reactor body 4.

[0063] In these embodiments, a sensor group 7 including a pressure sensor 701 and a temperature sensor 702 is used. The pressure sensor 701 and the temperature sensor 702 can detect the state inside the reactor body 4 in real time, and provide feedback signals for heating, gas phase valve 2 and liquid phase valve 3, so as to realize precise closed-loop control of temperature and pressure and avoid experimental errors caused by fluctuations in operating conditions.

[0064] It should be noted that temperature is a key parameter affecting the chemical reaction rate and electrochemical process between the corrosive medium and the working electrode 103. The temperature sensor 702 monitors the temperature inside the reaction vessel 4 in real time and accurately, providing feedback signals to the heating furnace 6 to ensure that the test process is always conducted under preset, stable temperature conditions. This guarantees the reliability and repeatability of the corrosion rate data and electrochemical test results.

[0065] It should be noted that pressure sensor 701 plays a crucial role in real-time monitoring, safety early warning, and process control. By continuously and accurately measuring the internal pressure of the reactor body 4, pressure sensor 701 provides vital assurance for the stable operation of the experimental apparatus: pressure data is the core basis for precise control of the corrosion process, and its interlocking control with the gas phase valve 2 ensures that the test pressure is always maintained under the set operating conditions; furthermore, pressure data is an important component of the experimental apparatus's safety protection system, promptly issuing alarms when abnormal pressure increases are detected, providing a critical time window for operators to take intervention measures. In addition, continuously changing pressure data provides dynamic characteristics of gas evolution and side reactions during the corrosion process, offering important reference for a deeper understanding of the corrosion mechanism of the tested metal material under high pressure.

[0066] It should be noted that the pressure sensor 701 can use a PX409-10WGUSBH type pressure sensor, and the temperature sensor 702 can use a TJ36-ICIN-116G-12 type temperature sensor.

[0067] In some optional embodiments, the three-electrode system 1 includes a reference electrode 101, a counter electrode 102, and a working electrode 103, with the counter electrode 102 and the working electrode 103 arranged opposite to each other. The reference electrode 101, the counter electrode 102, and the working electrode 103 pass through the vessel cover 5 and extend into the reactor body 4.

[0068] In these embodiments, the design includes a reference electrode 101, a counter electrode 102, and a working electrode 103. The working electrode 103 (made from the metal material to be tested) simulates the material surface of the actual equipment in the corrosive medium, and a corresponding electrochemical corrosion reaction occurs within the reaction vessel 4, which is beneficial for simulating the real corrosion process. Furthermore, the reference electrode 101 provides a known, stable, and unchanging electrode potential reference that does not change with the loop current, providing a reliable reference point for the potential measurement of the working electrode 103. This allows for precise measurement and control of the working electrode 103's potential, ensuring the accuracy and reproducibility of all potential-related data (e.g., self-corrosion potential, polarization curves). Additionally, the counter electrode 102 can be an inert electrode, providing a loop channel for electron exchange by the working electrode 103, ensuring a closed current loop and guaranteeing the accuracy of the working electrode 103's measurements.

[0069] It should be noted that during the testing process, the working electrode 103 will generate electrochemical test signals (such as corrosion current and corrosion resistance) based on chemical reactions, which is the direct carrier of corrosion behavior inside the reactor body 4.

[0070] In some optional embodiments, the experimental apparatus further includes a rupture disc 9, which is disposed on the pressure relief channel of the vessel cover 5 and communicates with the interior of the reaction vessel body 4.

[0071] In these embodiments, a rupture disc 9 is installed inside the experimental apparatus and connected to the reactor body 4. When the pressure inside the reactor body 4 exceeds the predetermined design limit of the rupture disc 9, rapid pressure relief can be achieved through the directional rupture of the rupture disc 9, providing an independent overpressure protection measure for the experimental apparatus.

[0072] It should be noted that because the rupture disc 9 has an irreversible mechanical response and does not rely on external control signals, it can compensate for the deficiencies of the active protection measures of the safety valve. Once the rupture disc 9 has been used, it needs to be replaced with a new one.

[0073] The present application is further illustrated below with reference to specific embodiments. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national / industry standards; if there is no corresponding national / industry standard, they are performed according to general international standards, conventional conditions, or conditions recommended by the manufacturer.

[0074] Example 1 like Figure 1 and Figure 2 As shown, an in-situ electrochemical corrosion testing method for simulating chlor-alkali operating conditions is used to simulate the corrosion process in the chlor-alkali industry, including: S1. The three-electrode system 1, including the working electrode 103, the reference electrode 102, and the counter electrode 101, is sealed and installed on the lid 5 of the experimental apparatus, so that the test surface of the working electrode 103 is exposed in the experimental space of the experimental apparatus, and the gas phase valve 2, the liquid phase valve 3, and the sensor group 7 are connected to the experimental space. S2. Open the liquid phase valve 3 to introduce an alkaline corrosive medium into the experimental space; open the gas phase valve 2 to replace the air in the experimental space or to form a preset atmosphere; S3. The experimental device is heated and the pressure is adjusted in a closed state to bring the alkaline corrosive medium to a preset temperature or preset pressure, and to bring the alkaline corrosive medium into contact with the test surface of the working electrode 103 to form a simulated environment. S4. The electrochemical response process changes of the working electrode 103 are collected in situ using a three-electrode system 1 to obtain the corrosion potential, corrosion current density, and impedance parameters of the material under test in an alkaline corrosive medium, thereby completing the in-situ electrochemical corrosion test; wherein, the electrochemical response includes at least one of open-circuit potential, polarization curve, and electrochemical impedance spectroscopy; wherein, the experimental setup also includes: The reactor body 4 and the lid 5 are attached to the reactor body 4 to form the experimental space of the experimental device; The simulation unit includes a gas phase valve 2, a liquid phase valve 3, a heating furnace 6, and a sensor group 7. The reactor body 4 is inserted into the heating furnace 6. The gas phase valve 2, the liquid phase valve 3, and the sensor group 7 are all inserted into the reactor cover 5, and the sensing end of the sensor group 7 is set deep into the reactor body 4 through the reactor cover 5.

[0075] The three-electrode system 1 includes a reference electrode 101, a counter electrode 102, and a working electrode 103. The counter electrode 102 and the working electrode 103 are arranged opposite to each other. The reference electrode 101, the counter electrode 102, and the working electrode 103 pass through the vessel cover 5 and extend into the reactor body 4.

[0076] The test surface of the working electrode 103 is positioned directly opposite the surface eroded by the alkaline corrosive medium.

[0077] The inner surface of the reactor body 4 is covered with an inert layer 401, the thickness of which is 1mm to 2mm; the material of the inert layer 401 is PTFE.

[0078] The experimental apparatus also includes a fastening unit 8, which is located between the reaction vessel body 4 and the vessel cover 5.

[0079] The fastening unit 8 includes a first fastening clamp 801, a second fastening clamp 802, a fastening block 803, a fastening groove 804, a fastening bolt 805, and a fastening bolt 805 knob. One end of the first fastening clamp 801 is hinged to one end of the second fastening clamp 802. The fastening block 803 is disposed in the other end of the first fastening clamp 801. The fastening groove 804 is disposed in the other end of the second fastening clamp 802. One end of the fastening bolt 805 is fixedly connected to the fastening bolt 805 knob. The other end of the fastening bolt 805 passes through the fastening groove 804 and is threadedly connected to the fastening block 803, so that the length of the fastening bolt 805 in the fastening groove 804 can be adjusted by the fastening bolt 805 knob.

[0080] The sensor group 7 includes a pressure sensor 701 and a temperature sensor 702, which pass through the lid 5 and extend into the reactor body 4.

[0081] The experimental apparatus also includes a rupture disc 9, which is placed on the pressure relief channel of the lid 5 and connected to the inside of the reactor body 4.

[0082] The specific experimental procedure is as follows: 1. Preparations before the experiment: (1) Check whether the PTFE lining of the reactor body 4 and the lid 5 is intact, and whether the fastening unit 8 is clean and free of foreign matter; (2) Confirm that the three-electrode system 1 is securely connected and that the surfaces of the reference electrode 101, working electrode 103 and counter electrode 102 are clean and free of contamination.

[0083] (3) Check whether the gas phase valve 2 and the liquid phase valve 3 are in the closed state, and whether the rupture disc 9 is undamaged.

[0084] 2. Media injection and sealing: (1) The corrosive medium for the experiment is injected through the liquid phase valve 3, and the liquid level does not exceed 2 / 3 of the volume of the reactor body 4.

[0085] (2) Install the vessel cover 5. First, put one end of the first fastening clamp 801 and the second fastening clamp 802 between the vessel cover 5 and the reactor body 4. Then, adjust the fastening bolt 805 by turning the fastening bolt 805 knob. At this time, the fastening bolt 805 passes through the fastening groove 804 and rotates between the fastening block 803, causing the other end of the first fastening clamp 801 and the second fastening clamp 802 to abut against the vessel cover 5.

[0086] (3) Inject inert gas (e.g., nitrogen) through gas phase valve 2 to replace the air in the reactor body 4.

[0087] 3. Parameter settings and startup: (1) Set the target temperature and heating / cooling program through the operating screen of the heating furnace 6.

[0088] (2) Turn on temperature sensor 702 and pressure sensor 701 to monitor real-time data inside reactor body 4.

[0089] (3) Connect to the electrochemical workstation and set the test parameters (e.g., scan rate, frequency range).

[0090] 4. Experimental Operation and Monitoring: (1) Start the heating program and observe the temperature changes of temperature sensor 702 and pressure changes of pressure sensor 701 to ensure that they are stable within the set range.

[0091] (2) Conduct electrochemical tests and record corrosion current, corrosion potential and impedance data in real time.

[0092] (3) If the pressure is abnormal, stop heating immediately and release the pressure through the gas phase valve 2.

[0093] 5. Procedures for ending the experiment: (1) Turn off the heating furnace 6 and let it cool naturally to room temperature.

[0094] (2) Discharge the medium through the liquid phase valve 3 and clean the reactor body 4 and the three-electrode system 1.

[0095] (3) Loosen the fastening unit 8, remove the lid 5, and check the condition of the seal and the liner.

[0096] 6. Safety Precautions: (1) Operating environment: 1) The experimental apparatus should be placed in a well-ventilated explosion-proof area, away from flammable and explosive materials; 2) Operators must wear acid and alkali resistant protective clothing, gloves and goggles.

[0097] (2) Pressure and temperature limitations: 1) It is strictly forbidden to exceed the burst pressure (12.5 MPa) and maximum design temperature (250℃) of the rupture disc 9. 2) When the pressure is too high, the rupture disc 9 will break automatically and must be replaced in time before it can be used again.

[0098] (3) Media compatibility: 1) Only use with corrosive media compatible with 316L stainless steel and PTFE.

[0099] 2) It is forbidden to inject highly corrosive and incompatible media such as hydrofluoric acid and concentrated sulfuric acid.

[0100] (4) Emergency handling: 1) In case of leakage: immediately stop the experiment, close the gas phase valve 2 and the liquid phase valve 3, and evacuate personnel.

[0101] 2) Sudden pressure rise: Activate gas phase valve 2 to relieve pressure. If ineffective, evacuate and wait for the rupture disc 9 to activate.

[0102] 7. Maintenance and Care: (1) Regular inspections: 1) Check the wear of the sealing mechanism monthly and replace aged seals in a timely manner.

[0103] 2) Clean the probes of the three-electrode system 1, temperature sensor 702, and pressure sensor 701 to avoid residual corrosive media affecting accuracy.

[0104] (2) Component replacement: 1) The rupture disc 9 needs to be replaced with a new one after each operation; 2) If the PTFE liner peels or is damaged, it needs to be repaired in time.

[0105] (3) Long-term discontinuation: 1) Drain the medium, clean and dry the reactor and pipelines.

[0106] 2) All valves are in the open position to prevent permanent deformation of the seals.

[0107] 8. Troubleshooting: (1) Large temperature fluctuation: It may be due to a fault in temperature sensor 702 or unstable power of heating furnace 6. Temperature sensor 702 needs to be calibrated, or the power supply used by heating furnace 6 needs to be checked.

[0108] (2) Abnormal pressure reading: It may be due to blockage of pressure sensor 701 or gas leakage. Pressure sensor 701 needs to be cleaned and the seals and valves of gas phase valve 2 need to be checked.

[0109] (3) Electrochemical signal noise: It may be due to loose connection of the three-electrode system 1 or contamination of the corrosive medium. It is necessary to reconnect the three-electrode system 1 or replace it with fresh corrosive medium.

[0110] (4) Leakage: It may be due to aging of the seal or insufficient tightening force. The seal needs to be replaced or the bolts 805 need to be tightened evenly.

[0111] In summary, the embodiments of this application provide an in-situ electrochemical corrosion testing method for chlor-alkali working condition simulation. This testing method integrates the chemical, physical, and electrochemical factors that experimental materials are subjected to in actual chlor-alkali industry into a controllable closed experimental space, realizing a leap from static approximate simulation to dynamic resetting and reproduction, thereby significantly improving the accuracy and data reliability of electrochemical corrosion testing simulation.

[0112] Furthermore, this application provides an in-situ electrochemical corrosion testing method for simulating chlor-alkali operating conditions. The experimental apparatus used in this method possesses excellent tolerance to high-temperature and strong alkaline environments and integrates a three-electrode system 1 for electrochemical measurement. This system can highly replicate the corrosive environment in actual production, thereby effectively promoting in-depth research on the corrosion behavior of alkali solution transportation pipelines and key equipment materials. The establishment of this testing method has significant engineering application value and theoretical guiding significance for improving the corrosion protection capability of the chlor-alkali industry's evaporation and solidification process and preventing safety accidents caused by corrosion.

[0113] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed in this application.

Claims

1. An in-situ electrochemical corrosion testing method for simulating chlor-alkali operating conditions, used to simulate the corrosion process of chlor-alkali industrial equipment or pipelines in an alkaline corrosive medium, characterized in that, The testing method includes: A three-electrode system, including a working electrode, a reference electrode, and a counter electrode, is sealed and installed in the lid of the experimental apparatus, so that the test surface of the working electrode is exposed in the experimental space of the experimental apparatus, and the gas phase valve, liquid phase valve, and sensor group are connected to the experimental space. The liquid phase valve is opened to introduce an alkaline corrosive medium into the experimental space; the gas phase valve is opened to replace the air in the experimental space or to form a preset atmosphere. The experimental device is heated and the pressure is adjusted in a closed state to bring the alkaline corrosive medium to a preset temperature or preset pressure, and to bring the alkaline corrosive medium into contact with the test surface of the working electrode to form a simulated environment. The electrochemical response process of the working electrode is collected in situ using the three-electrode system to obtain the corrosion potential, corrosion current density, and impedance parameters of the material under test in the alkaline corrosive medium, thereby completing the in-situ electrochemical corrosion test; wherein, the electrochemical response includes at least one of open circuit potential, polarization curve, and electrochemical impedance spectroscopy; The experimental apparatus includes: The reactor body and the reactor lid, wherein the reactor lid abuts against the reactor body to form the experimental space of the experimental apparatus; The simulation unit includes the gas phase valve, the liquid phase valve, the heating furnace, and the sensor group. The reactor body is inserted into the heating furnace. The gas phase valve, the liquid phase valve, and the sensor group are all inserted into the reactor lid, and the sensing end of the sensor group is inserted into the reactor body through the reactor lid.

2. The test method according to claim 1, characterized in that, The alkaline corrosive medium contains 10% to 50% alkaline substances by mass; and the alkaline corrosive medium contains Cl. - F - SO4 2- At least one impurity ion in it.

3. The test method according to claim 1, wherein the preset temperature is 80℃~250℃; and the preset pressure is 0.1MPa~12.5MPa.

4. The test method according to claim 1, characterized in that, The three-electrode system includes a reference electrode, a counter electrode, and a working electrode. The counter electrode and the working electrode are arranged opposite to each other. The reference electrode, the counter electrode, and the working electrode pass through the vessel lid and extend into the reactor body. The exposed area of ​​the test surface of the working electrode is 0.1 cm². 2 ~5cm 2 .

5. The test method according to claim 4, characterized in that, The test surface of the working electrode is positioned directly opposite the erosion surface of the alkaline corrosive medium, or The test surface of the working electrode is located within the flow path region of the alkaline corrosive medium.

6. The test method according to claim 1, characterized in that, The inner surface of the reactor body is covered with an inert layer, the thickness of which is 1mm to 3mm.

7. The test method according to claim 1, characterized in that, The experimental apparatus also includes a sealing and fastening unit, which is disposed between the reaction vessel body and the vessel cover.

8. The test method according to claim 7, characterized in that, The fastening unit includes a first fastening clamp, a second fastening clamp, a fastening block, a fastening groove, a fastening bolt, and a fastening bolt knob. One end of the first fastening clamp is hinged to one end of the second fastening clamp. The fastening block is disposed in the other end of the first fastening clamp. The fastening groove is disposed in the other end of the second fastening clamp. One end of the fastening bolt is threadedly connected to the fastening bolt knob. The other end of the fastening bolt passes through the fastening groove and is fixedly connected to the fastening block, so that the length of the fastening bolt in the fastening groove can be adjusted by the fastening bolt knob.

9. The test method according to claim 1, characterized in that, The sensor group includes a pressure sensor and a temperature sensor, which pass through the vessel lid and extend into the reactor body.

10. The test method according to claim 1, characterized in that, The experimental apparatus further includes a rupture disc, which is disposed on the pressure relief channel of the vessel lid and communicates with the interior of the reactor.

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