Corrosion resistance evaluation device and method for water-cooling radiator of internal cooling system of converter valve

Abstract

The invention discloses a device and a method for evaluating corrosion resistance of a water cooling radiator of a converter valve internal cooling system, a water distribution system is provided with an integrated water quality monitoring system, gas is introduced through a dosing and gas distribution system to reach set water quality, and the gas is introduced into an experimental pipeline system through a circulating water pump capable of adjusting flow; the electrochemical monitoring system is used for testing the electrochemical performance of the working electrode, graphite electrodes are arranged on the two sides of the working electrode and directly connected with an external high-voltage power supply, and the electric field characteristics of an ultra-high-voltage direct-current transmission converter valve inner-cooling system water-cooling radiator are simulated. The device can quantify the corrosion rate of the water-cooling radiator and predict the service life of the radiator in an operation environment. The method is helpful for determining the corrosion mechanism of the water-cooling radiator, and provides guidance for corrosion prevention and scale prevention of the converter station, so that the reliability of converter station equipment is improved, and potential safety hazards are reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of anti-corrosion of power equipment, and in particular to a device and method for evaluating the corrosion resistance of a water-cooled radiator in an internal cooling system of a converter valve. By combining electrochemical testing technology with high-voltage electric field simulation, the device and method can accurately evaluate the corrosion behavior of radiator materials in an actual operating environment, thereby providing a scientific basis for optimizing material selection, anti-corrosion measures and improving operating reliability of converter station equipment. Background Art

[0002] Ultra-high voltage direct current transmission technology is widely used in large-scale long-distance power transmission. One of its core equipment, the converter valve, needs to rely on an internal cooling system to achieve efficient heat dissipation during operation. However, the water-cooled radiator in the internal cooling system is exposed to high-voltage direct current electric fields and complex cooling medium environments for a long time, and is prone to corrosion. The corrosion of the radiator will cause metal ions such as aluminum to enter the cooling water, further causing scaling problems on the voltage-equalizing electrodes, and ultimately affecting the operational safety and maintenance costs of the converter valve.

[0003] At present, the research on the corrosion behavior of the water-cooled radiator of the converter valve is mainly divided into static corrosion behavior research and dynamic corrosion rate testing. Among them, the static immersion experiment uses simple electrochemical measurements. These methods are difficult to accurately simulate the effects of ultra-high voltage electric fields and dynamic cooling media on corrosion behavior. The dynamic corrosion performance evaluation only characterizes the corrosion rate of the radiator through the aluminum ion content in the circulating water, which has the disadvantages of low reliability, large errors, and long test cycles. Therefore, it is urgent to develop a corrosion resistance performance evaluation method and device that can relatively realistically simulate the actual working conditions of the radiator, so as to deeply reveal its corrosion mechanism, quantify the corrosion rate, and provide reliable data support for material optimization design and the formulation of anti-corrosion measures.

[0004] In addition, the existing technology has deficiencies in dynamic water quality monitoring and accurate determination of corrosion rate. It is impossible to adjust the chemical conditions of the cooling medium (such as pH value, dissolved oxygen content and conductivity) in real time and efficiently measure corrosion parameters. When the radiator material is replaced, the cooling water quality cannot be quantitatively controlled. Therefore, the development of an electrochemical testing device with both high precision and dynamic control capabilities has become the key to solving this problem. Summary of the invention

[0005] In order to overcome the above technical problems, the present invention discloses a device and method for evaluating the corrosion resistance of a water-cooled radiator in a converter valve internal cooling system, aiming to solve the problem of equipment failure and reduced operating efficiency caused by corrosion of radiator materials in the operating environment of a UHV DC transmission converter station. By simulating a high-voltage DC electric field and a complex cooling medium environment, the present invention proposes a device that comprehensively utilizes electrochemical methods and dynamic simulation technology, which can accurately measure the corrosion resistance of radiator materials in an actual operating environment. The corrosion mechanism is also deeply revealed to provide scientific guidance for equipment material selection, optimization of anti-corrosion measures, and operation management.

[0006] The present invention provides the following technical solutions:

[0007] The corrosion resistance evaluation device of the water-cooled radiator of the converter valve internal cooling system includes a water distribution system, an air distribution system, an experimental pipeline system, an electrochemical monitoring system and an external high-voltage power supply;

[0008] The water distribution system is equipped with an integrated water quality monitoring system. The set water quality is achieved by introducing gas through the dosing and gas distribution system, and the gas is introduced into the experimental pipeline system through a circulating water pump with an adjustable flow rate. The electrochemical monitoring system performs an electrochemical performance test on the working electrode. Graphite electrodes are arranged on both sides of the working electrode and are directly connected to an external high-voltage power supply to simulate the electric field characteristics of the water-cooled radiator of the internal cooling system of the ultra-high voltage direct current transmission converter valve.

[0009] Specific:

[0010] The water distribution system includes a container, which is a sealed cylindrical container;

[0011] The top of the container is provided with a water inlet pipe, a medicine adding pipe, an air inlet pipe, a circulating water return pipe and an air outlet pipe;

[0012] The water inlet pipe is directly connected to the ultrapure water maker through a valve;

[0013] The intake pipe is directly connected to the gas distribution system through the intake valve;

[0014] A circulating water outlet pipe is provided at the bottom of the container, and the circulating water outlet pipe is connected with a circulating water pump, an experimental pipeline system and a circulating water return pipe through a circulating water outlet pipe valve to form a circulating water circuit;

[0015] The air outlet pipe is connected to the liquid sealing device to maintain the air pressure balance inside and outside the container and isolate the air;

[0016] A water quality monitoring instrument is installed inside the container, which includes a pH electrode, a dissolved oxygen meter electrode and a conductivity electrode; the water quality monitoring instrument is connected to an integrated digital display control box to monitor the water quality indicators in the container in real time.

[0017] The gas distribution system comprises a high-purity nitrogen cylinder and an oxygen cylinder. The high-purity nitrogen cylinder and the oxygen cylinder are connected to an air inlet valve through a gas mass flow meter, and the dissolved oxygen content in the container is regulated by the air inlet valve.

[0018] The experimental pipeline system includes a PVC pipe, both ends of which are connected to a circulating water outlet pipe and a circulating water return pipe respectively. Electrode jacks / grooves are left on the wall of the PVC pipe at intervals, and a counter electrode platinum column electrode, a reference electrode and a working electrode are inserted in sequence, and a first graphite electrode and a second graphite electrode are arranged on both sides of the working electrode.

[0019] The electrochemical monitoring system comprises an electrochemical workstation, which is directly connected to a counter electrode, a platinum column electrode, a reference electrode and a working electrode, and is used to test the electrochemical characteristics of the working electrode to be tested.

[0020] The external high-voltage power supply is a high-voltage direct current power supply, which is connected to the first graphite electrode and the second graphite electrode to simulate the potential difference between two adjacent radiators of the ultra-high voltage direct current transmission converter valve.

[0021] The water distribution system of the present invention comprises a cylindrical organic glass container, the interior of which is equipped with an integrated water quality monitoring system, which can monitor water quality parameters (such as pH, conductivity and dissolved oxygen content) in real time. Through the valve-type dosing pipe and the air inlet pipe, the chemical condition regulation of the cooling water and the air tightness of the device can be achieved, such as adjusting the dissolved oxygen concentration, pH value and conductivity so that the water quality reaches the simulated target environment. The container is connected through channels such as the dosing pipe and the air inlet pipe to achieve the regulation of the target water quality and can simulate a variety of cooling water chemical conditions. The circulating water pump introduces the cooling water from the container into the experimental pipeline to form a dynamic water cycle.

[0022] The gas distribution system of the present invention is equipped with gas sources of high-purity nitrogen and oxygen, and the gas injection amount is accurately controlled by a mass flow meter and a regulating valve to achieve regulation of dissolved oxygen content and simulate the redox environment when the radiator is running.

[0023] The experimental pipeline system of the present invention uses a section of Φ20×2.4mm PVC pipe, and electrode slots are arranged at a certain interval in the pipe section for inserting the working electrode, the counter electrode (platinum column electrode), the reference electrode and the graphite electrode to form a complete electrochemical measurement circuit. The circulating water pump provides a stable flow rate for the system to simulate the dynamic cooling water environment. Graphite electrodes are arranged on both sides of the working electrode to simulate the influence of the high voltage characteristics of the radiator inside the converter valve on corrosion.

[0024] The electrochemical monitoring system of the present invention connects the working electrode, the reference electrode and the counter electrode through an electrochemical workstation to measure the electrochemical properties of the radiator material in real time, including key parameters such as open circuit potential, corrosion current density, polarization resistance, etc., and provides accurate kinetic data for corrosion behavior.

[0025] The invention adds an external high-voltage power supply to provide a high-voltage direct current electric field to simulate the high-voltage characteristics of the radiator in the operating environment of the converter valve, so that the electrochemical measurement is closer to the actual working condition.

[0026] A method for evaluating the corrosion resistance of a water-cooled radiator in a converter valve internal cooling system adopts the device for evaluating the corrosion resistance of a water-cooled radiator in a converter valve internal cooling system; the method comprises the following steps:

[0027] Step 1: Cut the working electrode to be tested into small pieces with a size of 30×10×1mm;

[0028] Step 2: Grind the cut working electrode to be tested with sandpaper of #400 to #1200 mesh until there are no scratches;

[0029] Step 3, placing the polished working electrode to be tested in anhydrous ethanol and deionized water for ultrasonic cleaning in turn;

[0030] Step 4: Dry the cleaned working electrode to be tested with a hair dryer at room temperature, and seal the non-working area with Teflon tape to control the working area exposed to the corrosive environment;

[0031] Step 5: insert the counter electrode platinum column electrode, the reference electrode and the processed working electrode as well as the first graphite electrode and the second graphite electrode on both sides of the working electrode into the corresponding electrode holes / grooves, and seal them with hot melt adhesive to ensure the sealing of the entire test tube section;

[0032] Step 6, connecting the counter electrode platinum column electrode, the reference electrode and the processed working electrode to the corresponding positions of the electrochemical workstation;

[0033] Step 7, connecting the first graphite electrode and the second graphite electrode to the positive and negative electrodes of a high-voltage DC power supply respectively;

[0034] Step 8: insert the pH electrode, dissolved oxygen meter electrode and conductivity electrode into the corresponding positions of the container, and connect the three water quality monitoring instruments to the integrated digital display control box to monitor the water quality indicators in the container in real time;

[0035] Step nine, close the circulating water outlet pipe valve and the air inlet valve, and insert the air outlet pipe into the liquid sealing device;

[0036] Step 10, open the valve of the water inlet pipe to drain water to the scale line of the container and then close the valve of the water inlet pipe; add medicine into the container to adjust the pH and conductivity of the corrosive medium;

[0037] Step 11, open the air inlet valve, control the flow of nitrogen or oxygen into the container through a gas mass flow meter, adjust the dissolved oxygen content in the water to the target value, and then close the air inlet valve;

[0038] Step 12: Open the circulating water outlet valve, then start the circulating water pump, turn on and adjust the high-voltage DC power supply to the required voltage, expose the working electrode to the corrosive environment for a certain period of time, then turn off the high-voltage DC power supply, and then start the electrochemical workstation for electrochemical testing.

[0039] Step 13, electrochemical testing: Use open circuit potential, electrochemical impedance spectroscopy (EIS), linear sweep voltammetry (LSV) and other techniques to quantify the corrosion rate, corrosion current density and polarization resistance, and analyze the corrosion morphology through scanning electron microscopy (SEM) to reveal the corrosion mechanism.

[0040] Step 14: Data analysis and evaluation: Collect data through the electrochemical workstation, combine the corrosion rate formula and morphology analysis to evaluate the corrosion resistance of the radiator material, and provide a basis for optimizing material design and process improvement.

[0041] The following computational analysis methods are included:

[0042] Method 1: Use an electrochemical workstation to test the relationship between the open circuit voltage and time of the working electrode, use electrochemical impedance spectroscopy to test the corrosion kinetics of the working electrode and the control steps of the corrosion rate, use linear sweep voltammetry to measure the voltage-current relationship of the working electrode, and use the Tafel extrapolation method to draw the Tafel curve and calculate the corrosion current density.

[0043] Method 2: The annual corrosion rate of the working electrode can be calculated using the following formula.

[0044]

[0045] Where K = 3272, which is used to convert the corrosion rate unit to mm / year;

[0046] Icorr is the corrosion current density, A / cm 2 ;

[0047] M is the molar mass of the metal in g / mol;

[0048] n is the number of electrons lost in the oxidation reaction of the metal;

[0049] F is the Faraday constant, F = 96500C / mol;

[0050] ρ is the density of the metal in g / cm 3 .

[0051] Method three: Scanning electron microscopy (SEM) is used to observe the corrosion morphology of the working electrode at different potentials to analyze the corrosion mechanism and evaluate the corrosion rate.

[0052] Compared with the prior art, the present invention has the following implementation effects:

[0053] 1) Simulating real working conditions: The device and method of the present invention can more accurately simulate the corrosion environment of the radiator in the converter valve by regulating the chemical environment of the cooling medium and applying a high-voltage electric field. The flow rate of the corrosive medium is regulated by a circulating water pump to simulate the radiator being flushed by cooling water.

[0054] 2) Efficient evaluation capability: The device and method of the present invention can measure key electrochemical parameters (such as corrosion current density and polarization resistance) in real time and quantify the corrosion rate and corrosion resistance of the material.

[0055] 3) Versatility: The apparatus and method of the present invention can flexibly adopt the application of a variety of electrochemical techniques (such as EIS, Tafel plot, SEM analysis, etc.), and can comprehensively evaluate the corrosion kinetics, morphology and mechanism of different radiator materials.

[0056] 4) Strong guidance: The device and method of the present invention can analyze the corrosion morphology and corrosion mechanism at different potentials, providing a scientific basis for radiator material optimization, anti-corrosion coating design and cooling water treatment solutions.

[0057] 5) Safety and reliability: The device and method of the present invention can effectively reduce the risk of equipment failure caused by radiator corrosion and improve the safety and reliability of converter station operation.

[0058] The present invention is suitable for evaluating the corrosion resistance of water-cooled radiators in the cooling system of converter valves, and for studying the corrosion behavior of other power equipment in complex chemical environments. It can also be used for corrosion resistance testing of industrial cooling systems, material development and optimization, and the application of electrochemical testing technology. The present invention can significantly improve the operating efficiency of power equipment, extend its service life, and reduce maintenance costs, providing a strong guarantee for the safe and stable operation of converter stations. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 This is a structural diagram of the device provided by the present invention.

[0060] Figure 2 This is a flow chart of the evaluation method provided in Example 1 of the present invention.

[0061] Figure 3 This is a Tafel curve diagram of the aluminum heat sink described in Example 2 of the present invention.

[0062] Figure 4This is a comparison chart of the corrosion rates of the aluminum radiator and the stainless steel radiator described in the second embodiment of the present invention as a function of the water channel current.

[0063] Figure 5 This is a corrosion morphology diagram of the aluminum heat sink at different potentials described in Example 2 of the present invention. DETAILED DESCRIPTION

[0064] The present invention is described in detail below in conjunction with the embodiments and drawings, but it should be understood that the embodiments and drawings are only used to exemplify the present invention and do not constitute any limitation on the protection scope of the present invention. All reasonable changes and combinations within the scope of the inventive concept of the present invention fall within the protection scope of the present invention.

[0065] The present invention relates to a method and device for evaluating the corrosion resistance of a water-cooled radiator in a converter valve internal cooling system, aiming to solve the corrosion problem of the radiator caused by long-term exposure to high-voltage electric fields and cooling media in an ultra-high voltage direct current transmission converter station environment. By constructing a dynamic electrochemical experimental system, the present invention achieves an accurate evaluation of the corrosion resistance of radiator materials, providing a scientific basis for material selection, process improvement, and anti-corrosion strategies.

[0066] The present invention will be further described below in conjunction with the accompanying drawings.

[0067] Embodiment 1

[0068] like Figure 1 The corrosion resistance evaluation device for the water-cooled radiator of the converter valve internal cooling system provided in this example includes a water distribution system, an air distribution system, an experimental pipeline system, an electrochemical monitoring system and an external high-voltage power supply;

[0069] The water distribution system comprises a container 1, which is a sealed cylindrical container;

[0070] The top of the container 1 is provided with a water inlet pipe 2, a drug adding pipe 3, an air inlet pipe 4, a circulating water return pipe 7 and an air outlet pipe 8;

[0071] The water inlet pipe 2 is directly connected to the ultrapure water maker through a valve and is used to supplement the experimental water;

[0072] The dosing pipe 3 adds chemical reagents through the valve to adjust the pH value and conductivity of the cooling water.

[0073] The air intake pipe 4 is directly connected to the air distribution system through the air intake valve 17, and is used to introduce nitrogen or oxygen to control the dissolved oxygen content;

[0074] A circulating water outlet pipe 6 is provided at the bottom of the container 1, and the circulating water outlet pipe 6 is connected to the circulating water pump 5, the experimental pipeline system and the circulating water return pipe 7 through the circulating water outlet pipe valve 26 to form a circulating water circuit; the dynamic circulation of cooling water is realized through the circulating water pump 5.

[0075] The air outlet pipe 8 is connected to the liquid sealing device 9 to maintain the air pressure balance inside and outside the container 1 and isolate the air;

[0076] A water quality monitoring instrument is provided inside the container 1 , and the water quality monitoring instrument includes a pH electrode 10 , a dissolved oxygen meter electrode 11 and a conductivity electrode 12 ; the water quality monitoring instrument is connected to an integrated digital display control box 13 to monitor the water quality indicators in the container 1 in real time.

[0077] The gas distribution system includes a high-purity nitrogen cylinder 14 and an oxygen cylinder 15 . The high-purity nitrogen cylinder 14 and the oxygen cylinder 15 are connected to an air inlet valve 17 via a gas mass flow meter 16 , and the air inlet valve 17 is used to regulate the dissolved oxygen content in the container 1 .

[0078] The experimental pipeline system includes a PVC tube 18, the two ends of which are respectively connected to the circulating water outlet pipe 6 and the circulating water return pipe 7. Electrode jacks / grooves are left on the wall of the PVC tube 18 at intervals, and a counter electrode platinum column electrode 19, a reference electrode 20 and a working electrode 21 are inserted in sequence, and a first graphite electrode 22 and a second graphite electrode 23 are arranged on both sides of the working electrode 21 for uniformly distributing the electric field.

[0079] The electrochemical monitoring system includes an electrochemical workstation 24, which is directly connected to the counter electrode platinum column electrode 19, the reference electrode 20 and the working electrode 21 to test the electrochemical characteristics of the working electrode to be tested.

[0080] The external high-voltage power supply is a high-voltage direct current power supply 25, which is connected to the first graphite electrode 22 and the second graphite electrode 23 to simulate the potential difference between two adjacent radiators of the ultra-high voltage direct current transmission converter valve.

[0081] like Figure 2 , the device is used in this embodiment, including the following test steps:

[0082] Step 1: Cut the working electrode to be tested into small pieces with a size of 30×10×1mm;

[0083] Step 2: Grind the cut working electrode to be tested with #400, #800, #1000, and #1200 grit sandpaper in turn until there are no scratches;

[0084] Step 3, placing the polished working electrode to be tested in anhydrous ethanol and deionized water for ultrasonic cleaning in turn;

[0085] Step 4: Dry the cleaned working electrode to be tested with a hair dryer at room temperature, and seal the non-working area with Teflon tape to control the working area exposed to the corrosive environment;

[0086] Step 5: insert the counter electrode platinum column electrode 19, the reference electrode 20, the processed working electrode 21, and the first graphite electrode 22 and the second graphite electrode 23 on both sides of the working electrode into the corresponding electrode holes / grooves, and use hot melt adhesive to seal them to ensure the sealing of the entire test tube section;

[0087] Step 6, connecting the counter electrode platinum column electrode 19, the reference electrode 20 and the processed working electrode 21 to the corresponding positions of the electrochemical workstation 24;

[0088] Step 7, connecting the first graphite electrode 22 and the second graphite electrode 23 to the positive and negative electrodes of the high voltage DC power supply 25 respectively;

[0089] Step eight, insert the pH electrode 10, the dissolved oxygen meter electrode 11 and the conductivity electrode 12 into the corresponding positions of the container 1, and connect the three water quality monitoring instruments to the integrated digital display control box 13 to monitor the water quality indicators in the container in real time;

[0090] Step nine, close the circulating water outlet pipe valve 26 and the air inlet valve 17, and insert the air outlet pipe 8 into the liquid sealing device 9;

[0091] Step 10, open the valve of the water inlet pipe 2 to drain water to the scale line 6L of the container 1, and then close the valve of the water inlet pipe 2; add medicine into the container 1 to adjust the pH and conductivity of the corrosive medium;

[0092] Step 11, open the air inlet valve 17, control the flow of nitrogen or oxygen into the container 1 through the gas mass flow meter 16, adjust the dissolved oxygen content in the water to the target value, and then close the air inlet valve 17;

[0093] Step 12: Open the circulating water outlet valve 26, then start the circulating water pump 5, start and adjust the high-voltage DC power supply 25 to the required voltage, expose the working electrode to the corrosive environment for a certain period of time, then turn off the high-voltage DC power supply 25, and then start the electrochemical workstation 24 to perform electrochemical testing.

[0094] Step 13, electrochemical testing: Use open circuit potential, electrochemical impedance spectroscopy (EIS), linear sweep voltammetry (LSV) and other techniques to quantify the corrosion rate, corrosion current density and polarization resistance, and analyze the corrosion morphology through scanning electron microscopy (SEM) to reveal the corrosion mechanism.

[0095] Step 14: Data analysis and evaluation: Collect data through the electrochemical workstation, combine the corrosion rate formula and morphology analysis to evaluate the corrosion resistance of the radiator material, and provide a basis for optimizing material design and process improvement.

[0096] The analysis methods include the following:

[0097] Method 1: Use an electrochemical workstation to test the relationship curve between the open circuit voltage and time of the working electrode, use electrochemical impedance spectroscopy to test the corrosion kinetics of the working electrode and the control steps of the corrosion rate, use linear sweep voltammetry to measure the voltage-current relationship of the working electrode, and use the Tafel extrapolation method to draw the Tafel curve and calculate the corrosion current density.

[0098] Method 2: The annual corrosion rate of the working electrode can be calculated using the following formula.

[0099]

[0100] Where K = 3272, which is used to convert the corrosion rate unit to mm / year;

[0101] Icorr is the corrosion current density, A / cm 2 ;

[0102] M is the molar mass of the metal in g / mol;

[0103] n is the number of electrons lost in the oxidation reaction of the metal;

[0104] F is the Faraday constant, F = 96500C / mol;

[0105] ρ is the density of the metal in g / cm 3 .

[0106] Method three: Scanning electron microscopy (SEM) is used to observe the corrosion morphology of the working electrode at different potentials to analyze the corrosion mechanism and evaluate the corrosion rate.

[0107] Example 2

[0108] Taking the internal cooling system of a converter station as an example, the test controls the conductivity of cooling water in container 1 to about 0.5μS / cm, pH to about 6.5, and dissolved oxygen to 200μg / L. The corrosion effect of water circuit current on the metal radiator is simulated by changing the voltage applied to both sides of the test piece (0, 200, 400, 600, 800V). The aluminum alloy radiator is selected as the research object. Before the test, the aluminum alloy radiator is cut into small pieces of 30×10×1mm in size and polished with #400 to #1200 grit sandpaper in turn to ensure that the surface is smooth and scratch-free. The sample is cleaned with anhydrous ethanol and deionized water in turn, and the non-working area is sealed with Teflon tape, and the exposed area of ​​the corrosion test is controlled to be 1cm2. Then the pH and conductivity of the cooling medium are adjusted through the water distribution system. Nitrogen is introduced into the container for deoxygenation, and the dissolved oxygen content of the cooling water is controlled to be 200μg / L to match the actual working conditions of the converter valve internal cooling system. Insert the working electrode, reference electrode, counter electrode and graphite rod electrodes on both sides of the working electrode into the corresponding slots in the experimental pipeline in turn, and seal them with hot melt adhesive. Connect the working electrode, reference electrode and counter electrode to the corresponding positions of the electrochemical workstation, and connect the graphite rod electrode to the positive and negative poles of the external high-voltage power supply. Connect the water quality monitoring instrument to the digital display control box to monitor the chemical indicators of the test medium in real time. Use a high-voltage power supply to apply a high-voltage DC electric field between adjacent simulation electrodes of the radiator, and the voltage magnitudes are (0, 200, 400, 600, 800V) in turn to simulate the operating electric field environment of the radiator in the converter valve. After the system runs in this corrosive environment for 6 hours. Turn on the electrochemical workstation for electrochemical testing. The experimentally measured Tafel curve of aluminum alloy is as follows Figure 3 As shown, according to Figure 3 The corrosion current density of aluminum alloy in this corrosive environment can be calculated, and then the corrosion rate can be calculated. The calculation results are as follows: Figure 4 After the test, the surface morphology of the aluminum alloy specimen was observed using SEM, as shown in Figure 5 As shown. Figure 5 The corrosion conditions and corrosion mechanisms of aluminum alloys at different potentials can be inferred.

Claims

1. A corrosion resistance evaluation device for a water-cooled radiator in a converter valve internal cooling system, characterized in that: Including water distribution system, gas distribution system, experimental pipeline system, electrochemical monitoring system and external high-voltage power supply; The water distribution system is equipped with an integrated water quality monitoring system. The set water quality is achieved by introducing gas through the dosing and gas distribution system, and the gas is introduced into the experimental pipeline system through a circulating water pump with an adjustable flow rate. The electrochemical monitoring system performs an electrochemical performance test on the working electrode. Graphite electrodes are arranged on both sides of the working electrode and are directly connected to an external high-voltage power supply to simulate the electric field characteristics of the water-cooled radiator of the internal cooling system of the ultra-high voltage direct current transmission converter valve.

2. The corrosion resistance evaluation device for a water-cooled radiator in a converter valve internal cooling system according to claim 1 is characterized in that: The water distribution system comprises a container (1), which is a sealed cylindrical container; The top of the container (1) is provided with a water inlet pipe (2), a drug adding pipe (3), an air inlet pipe (4), a circulating water return pipe (7) and an air outlet pipe (8); The water inlet pipe (2) is directly connected to the ultrapure water making machine through a valve; The air intake pipe (4) is directly connected to the air distribution system through an air intake valve (17); A circulating water outlet pipe (6) is provided at the bottom of the container (1), and the circulating water outlet pipe (6) is connected to a circulating water pump (5), an experimental pipeline system and a circulating water return pipe (7) through a circulating water outlet pipe valve (26) to form a circulating water circuit; The air outlet pipe (8) is connected to the liquid sealing device (9) to maintain the air pressure balance inside and outside the container (1) and to isolate the air; A water quality monitoring instrument is provided inside the container (1), and the water quality monitoring instrument comprises a pH electrode (10), a dissolved oxygen meter electrode (11), and a conductivity electrode (12); the water quality monitoring instrument is connected to an integrated digital display control box (13) to monitor the water quality index in the container (1) in real time.

3. The corrosion resistance evaluation device for a water-cooled radiator in a converter valve internal cooling system according to claim 2 is characterized in that: The gas distribution system comprises a high-purity nitrogen cylinder (14) and an oxygen cylinder (15). The high-purity nitrogen cylinder (14) and the oxygen cylinder (15) are connected to an air inlet valve (17) via a gas mass flow meter (16), and the dissolved oxygen content in the container (1) is regulated via the air inlet valve (17).

4. The corrosion resistance evaluation device for a water-cooled radiator in a converter valve internal cooling system according to claim 2, characterized in that: The experimental pipeline system comprises a PVC pipe (18), the two ends of which are respectively connected to a circulating water outlet pipe (6) and a circulating water return pipe (7), and electrode insertion holes / grooves are reserved on the pipe wall of the PVC pipe (18) at intervals, into which a counter electrode platinum column electrode (19), a reference electrode (20) and a working electrode (21) are inserted in sequence, and a first graphite electrode (22) and a second graphite electrode (23) are arranged on both sides of the working electrode (21).

5. The corrosion resistance evaluation device for a water-cooled radiator in a converter valve internal cooling system according to claim 4 is characterized in that: The electrochemical monitoring system comprises an electrochemical workstation (24) which is directly connected to a counter electrode platinum column electrode (19), a reference electrode (20) and a working electrode (21) to test the electrochemical characteristics of the working electrode to be tested.

6. The corrosion resistance evaluation device for a water-cooled radiator in a converter valve internal cooling system according to claim 1, characterized in that: The external high-voltage power supply is a high-voltage direct current power supply (25), which is connected to the first graphite electrode (22) and the second graphite electrode (23) to simulate the potential difference between two adjacent heat sinks of the ultra-high voltage direct current transmission converter valve.

7. A method for evaluating the corrosion resistance of a water-cooled radiator in a converter valve internal cooling system, characterized in that: The corrosion resistance evaluation device for a water-cooled radiator in an internal cooling system of a converter valve according to any one of claims 1 to 6 is adopted; The method comprises the following steps: Step 1: Cut the working electrode to be tested into small pieces with a size of 30×10×1mm; Step 2: Grind the cut working electrode to be tested with #400, #800, #1000, and #1200 grit sandpaper in turn until there are no scratches; Step 3, placing the polished working electrode to be tested in anhydrous ethanol and deionized water for ultrasonic cleaning in turn; Step 4: Dry the cleaned working electrode to be tested with a hair dryer at room temperature, and seal the non-working area with Teflon tape to control the working area exposed to the corrosive environment; Step 5: insert the counter electrode platinum column electrode (19), the reference electrode (20), the processed working electrode (21), and the first graphite electrode (22) and the second graphite electrode (23) on both sides of the working electrode into the corresponding electrode holes / grooves, and use hot melt adhesive to seal them to ensure the sealing of the entire test tube section; Step 6, connecting the counter electrode platinum column electrode (19), the reference electrode (20) and the processed working electrode (21) to the corresponding positions of the electrochemical workstation (24); Step 7, connecting the first graphite electrode (22) and the second graphite electrode (23) to the positive and negative electrodes of a high-voltage direct current power source (25) respectively; Step eight, inserting the pH electrode (10), the dissolved oxygen meter electrode (11) and the conductivity electrode (12) into the corresponding positions of the container (1), and connecting the three water quality monitoring instruments to the integrated digital display control box (13) to monitor the water quality indicators in the container in real time; Step nine, close the circulating water outlet pipe valve (26) and the air inlet valve (17), and insert the air outlet pipe (8) into the liquid sealing device (9); Step 10, opening the valve of the water inlet pipe (2) to drain water to the scale line of the container (1) and then closing the valve of the water inlet pipe (2); adding drugs into the container (1) to adjust the pH and conductivity of the corrosive medium; Step 11, opening the air inlet valve (17), controlling the flow rate of nitrogen or oxygen introduced into the container (1) through the gas mass flow meter (16), adjusting the dissolved oxygen content in the water to a target value, and then closing the air inlet valve (17); Step twelve, open the circulating water outlet pipe valve (26), then start the circulating water pump (5), start and adjust the high-voltage DC power supply (25) to the required voltage; after the working electrode is exposed to the corrosive environment for a certain period of time, turn off the high-voltage DC power supply (25), and then start the electrochemical workstation (24) to perform electrochemical testing.

8. The corrosion resistance evaluation method of the water-cooled radiator of the converter valve internal cooling system according to claim 1 is characterized in that: Also includes: Step 13, electrochemical testing: using open circuit potential, electrochemical impedance spectroscopy (EIS), and linear sweep voltammetry (LSV) techniques to quantify corrosion rate, corrosion current density, and polarization resistance, and using scanning electron microscopy (SEM) to analyze corrosion morphology and reveal corrosion mechanisms; Step 14: Data analysis and evaluation: Collect data through the electrochemical workstation, combine the corrosion rate formula and morphology analysis to evaluate the corrosion resistance of the radiator material, and provide a basis for optimizing material design and process improvement.

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