Method for cleaning of a voltage sharing electrode of a converter valve

Abstract

The application discloses a method for removing scale of a voltage-sharing electrode of a converter valve, and the method takes an aluminum radiator in the converter valve as a cathode and takes each voltage-sharing electrode as an anode, connects the aluminum radiator with a negative electrode of a direct-current power supply generator, connects each voltage-sharing electrode in series and then connects the voltage-sharing electrodes with a positive electrode of the direct-current power supply generator, forms an electric loop through cooling water in the converter valve, applies a current to the electric loop by the direct-current power supply generator, and makes the cooling water in the converter valve generate an electrolysis reaction, so that scale on the voltage-sharing electrode is removed. The method has the advantages of simple and efficient scale removal, and eliminates a large amount of manual disassembly and cleaning work.

Description

Technical Field

[0001] This invention belongs to the technical field of pressure equalization electrodes for converter valves, and relates to a method for descaling pressure equalization electrodes for converter valves. Background Technology

[0002] With the continuous development of power systems and the construction of new power systems, a large number of ultra-high voltage (UHV) and high voltage (HVDC) transmission projects have been built and put into operation. Converter stations are the parts in UHV and HVDC transmission systems that realize the energy conversion between AC and DC, and are also the central link in DC transmission. The converter valve is the most core and critical component of the converter station for AC-DC conversion. During normal operation, it withstands large currents and high voltages, generating a large amount of heat that needs to be dissipated by the internal cooling water system. Many equalizing electrodes (i.e., equalizing platinum electrodes) are installed on the cooling water pipes of the converter valve cooling system to control the potential difference between various components in the cooling water system. Due to the presence of leakage current, corrosion of the thyristor aluminum radiator in the converter valve cooling water system produces Al... 3+ Corrosion products form on the equalizing electrode, leading to scaling. This scaling not only affects the equalizing capacity of the electrode but can also cause leaks. In recent years, there have been several cases of converter valve failures caused by scaling on the equalizing electrode.

[0003] Therefore, descaling the equalizing electrodes is an important routine task in the operation and maintenance of converter valve cooling systems. Currently, descaling of equalizing electrodes mainly involves manually removing them from the cooling water pipes during converter station maintenance and then cleaning them one by one. This method is time-consuming. Converter valves typically have thousands of platinum electrodes, making manual descaling extremely labor-intensive. Furthermore, limited downtime during maintenance prevents the complete descaling of all electrodes, often resulting in incomplete descaling. Additionally, the need to replace sealing rings during electrode removal and installation increases risks and reduces economic efficiency. Therefore, a highly efficient method for descaling the equalizing electrodes of converter valves is urgently needed to solve these problems. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a simple and efficient method for descaling the equalizing electrode of a converter valve.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution.

[0006] A method for descaling the equalizing electrodes of a converter valve involves using an aluminum radiator in the converter valve as the cathode and each equalizing electrode as the anode. The aluminum radiator is connected to the negative terminal of a DC power generator, and each equalizing electrode is connected in series to the positive terminal of the DC power generator. This allows the DC power generator, the aluminum radiator, and the equalizing electrodes to form an electrical circuit through the cooling water inside the converter valve. The DC power generator applies current to the electrical circuit, and the equalizing electrodes and the aluminum radiator act as electrodes to cause an electrolytic reaction in the internal cooling water, thereby removing the scale on the equalizing electrodes.

[0007] In the above-mentioned descaling method for the equalizing electrode of the converter valve, preferably, the current applied to the electrical circuit by the DC power generator is 4A to 6A.

[0008] Preferably, in the above-mentioned descaling method for the equalizing electrode of the converter valve, before the DC power generator applies current, water is added to the water circuit between the equalizing electrode and the aluminum heat sink through the internal cooling water system of the converter valve to fill the water circuit with water, and the conductivity of the internal cooling water is controlled to be 50μs / cm to 100μs / cm by adding electrolyte NaCl.

[0009] In the above-mentioned descaling method for the equalizing electrode of the converter valve, preferably, there are two aluminum heat sinks connected in series and then connected to the negative terminal of the DC power generator.

[0010] In the above-mentioned descaling method for the equalizing electrode of the converter valve, preferably, the electrolysis time of the equalizing electrode is 30 min to 60 min.

[0011] Preferably, in the above-mentioned descaling method for the equalizing electrode of the converter valve, an ammeter is installed in the electrical circuit to monitor the circuit current.

[0012] In the above-mentioned descaling method for the equalizing electrode of the converter valve, preferably, after the scale on the equalizing electrode is dissolved, the internal cooling water in the internal cooling water system is replaced to meet the subsequent operating requirements of the converter valve.

[0013] The descaling method for the equalizing electrode of the converter valve of the present invention forms an electrical circuit with an aluminum heat sink and an equalizing electrode and a DC power generator, with the aluminum heat sink as the cathode and the equalizing electrode as the anode (all equalizing electrodes of a valve tower can be connected in series). Current is applied to the electrical circuit through the DC power generator, thereby causing an electrolytic reaction in the equalizing electrode region: 4OH⁻ - -4e - = 2H₂O + O₂, due to the ionization reaction of the internal cooling water: H₂O ⇌ H₂O + +OH - OH- produced by the ionization of H2O - It is continuously consumed near the equalizing electrode, causing H +Large amounts of deposits accumulate and form a strong acid. The scale formed on the equalizing electrode is alkaline scale such as aluminum hydroxide scale, which will dissolve in a strong acid environment, thereby removing the scale on the equalizing electrode.

[0014] Compared with the prior art, the advantages of the present invention are as follows: This invention removes scale from the equalizing electrode using an electrochemical method. A DC power supply is applied to the circuit, causing an electrolytic reaction in the equalizing platinum electrode region that continuously consumes H₂O and generates OH⁻. - , making H + Large amounts of aluminum hydroxide scale accumulate, forming a strong acid environment. This acidic environment dissolves the scale on the equalizing electrode, thus removing it. The method of this invention eliminates a significant amount of manual disassembly and cleaning work, offering simplicity and high efficiency. It effectively resolves the contradiction between scale removal from equalizing electrodes and insufficient maintenance time, avoiding the problem of untimely scale removal. It also reduces maintenance risks associated with electrode disassembly and reduces the need for sealing ring replacement, thereby ensuring equipment safety and reducing operating costs. Attached Figure Description

[0015] Figure 1 This is a schematic diagram illustrating the process principle of the descaling method for the equalizing electrode of the converter valve in Embodiment 1 of the present invention.

[0016] Legend: 1. DC power generator; 2. Ammeter; 3. Equalizing electrode; 4. Aluminum heat sink; 5. Cooling water pipe; 6. Converter valve main cooling water pipe; 7. Insulated wire. Detailed Implementation

[0017] The present invention will be further described below with reference to the accompanying drawings and specific preferred embodiments, but this does not limit the scope of protection of the present invention. All materials and instruments used in the following embodiments are commercially available.

[0018] Example 1 A method for descaling the equalizing electrode of a converter valve according to the present invention, such as... Figure 1As shown, an aluminum radiator 4 and all equalizing electrodes 3 (equalizing platinum electrodes) of the Y / DA valve tower of a ±800kV converter station are connected to a DC power generator 1 to form an electrical circuit. The equalizing electrodes 3 are located on the main cooling water pipe 6 of the converter valve. All equalizing electrodes 3 are connected in series to the positive terminal of the DC power generator 1 via insulated wires 7. There are two aluminum radiators 4, which are connected in series to the negative terminal of the DC power generator 1 via insulated wires 7. A cooling water pipe 5 connects the aluminum radiators 4 to the main cooling water pipe 6 of the converter valve. After the electrical circuit is connected, a 1mol / L NaCl solution and internal cooling water are slowly added to the water circuit between the equalizing electrodes 3 and the aluminum radiators 4 to increase the conductivity of the internal cooling water to 100μs / cm. Once the internal cooling water is full and the water quality meets the requirements, and the electrolysis circuit is confirmed to be functioning correctly, a 5A electrolysis current is applied to the equalizing electrode 3 via the DC power generator 1 for 30 minutes of electrolysis. An ammeter 2 is installed in the circuit to monitor the circuit current. The ammeter 2 can be located at the positive terminal of the DC power generator 1, but is not limited to this. After electrolysis, the internal cooling water system is drained. A random inspection of the equalizing electrode on the low-Y / DA valve tower (Electrode I) after descaling and comparing it with the equalizing electrode on the low-Y / DB valve tower (Electrode I) without descaling revealed that the scale on the equalizing electrode on the low-Y / DA valve tower (Electrode I) was successfully removed.

[0019] Example 2 A descaling method for the equalizing electrodes of a converter valve according to the present invention involves forming an electrical circuit between an aluminum radiator 4 and all equalizing electrodes 3 of a ±800kV converter station's Pole II high Y / YA valve tower and a DC power generator 1. Each equalizing electrode 3 is connected in series to the positive terminal of the DC power generator 1, and the aluminum radiator 4 is connected to the negative terminal of the DC power generator 1. After the electrical circuit is connected, a 1 mol / L NaCl solution and internal cooling water are slowly added to the water circuit between the equalizing electrodes 3 and the aluminum radiator 4 to increase the conductivity of the internal cooling water to 100 μS / cm. Once the internal cooling water is full and the water quality meets the requirements, and after confirming that the electrolysis circuit is working correctly, a 6A electrolysis current is applied to the equalizing electrodes via a DC power supply for 60 minutes of electrolysis. Then, the internal cooling water system is drained. A random inspection of the pressure equalization electrode on the high Y / YA valve tower of the second pole, after descaling, was compared with the pressure equalization electrode on the high Y / YB valve tower of the second pole, which had not been descaled. It was found that the scale on the pressure equalization electrode on the high Y / YA valve tower of the second pole was successfully removed.

[0020] Comparative Example 1 A descaling method for the equalizing electrode of a converter valve differs from Example 1 in that the electrolysis current is different. A DC power generator 1 applies a 1A electrolysis current to the equalizing electrode 3 for 30 minutes. A random inspection of the equalizing electrode on the low-Y / DA valve tower after descaling and compared it with the equalizing electrode on the low-Y / DB valve tower without descaling revealed no significant change in the scale on the equalizing electrode of the low-Y / DA valve tower.

[0021] Comparative Example 2 A descaling method for the equalizing electrode of a converter valve differs from Example 1 in that the electrolysis current is different. An 8A electrolysis current is applied to the equalizing electrode 3 via a DC power generator 1 for 30 minutes. A random inspection of the equalizing electrode on the low-Y / DA valve tower after descaling and compared it to the equalizing electrode on the low-Y / DB valve tower without descaling revealed that the equalizing electrode on the low-Y / DA valve tower still had a large amount of scale due to excessive anodic electrolysis.

[0022] Comparative Example 3 A descaling method for the equalizing electrode of a converter valve differs from Example 1 in that the electrolysis time is different. A 5A electrolysis current is applied to the equalizing electrode 3 via a DC power generator 1 for 5 minutes. A random inspection of the equalizing electrode on the low-Y / DA valve tower after descaling and the equalizing electrode on the low-Y / DB valve tower without descaling revealed no significant change in the scale on the equalizing electrode of the low-Y / DA valve tower.

[0023] Comparative Example 4 A descaling method for the equalizing electrode of a converter valve differs from Example 1 in that the electrolysis time is different; a 5A electrolysis current is applied to the platinum electrode using a DC power supply for 70 minutes. Random inspection of the equalizing electrode on the low-Y / DA valve tower after descaling revealed the formation of some deposits.

[0024] Comparative Example 5 A descaling method for the equalizing electrode of a converter valve differs from Example 2 in that the conductivity of the internal cooling water is different. After the electrical circuit is connected, the water circuit between the equalizing electrode 3 and the aluminum radiator 4 is filled with water, with a conductivity of 0.1 μS / cm. A random inspection of the equalizing electrode on the high Y / YA valve tower (Pole II) after descaling and compared it with the equalizing electrode on the high Y / YB valve tower (Pole II) without descaling revealed that the scale on the equalizing electrode on the high Y / YA valve tower (Pole II) was not removed.

[0025] Comparative Example 6 A descaling method for the equalizing electrode of a converter valve differs from Example 2 in that the conductivity of the internal cooling water is different. After the electrical circuit is connected, a 1 mol / L NaCl solution and internal cooling water are slowly added to the water circuit between the equalizing electrode 3 and the aluminum radiator 4 to increase the conductivity of the internal cooling water to 150 μS / cm. Spot checks of the equalizing electrode on the II high-Y / YA valve tower after descaling revealed a significant amount of deposits, indicating that the scale samples could not be removed.

[0026] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the spirit and technical essence of the present invention. Therefore, any simple modifications, equivalent substitutions, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall still fall within the protection scope of the technical solutions of the present invention.

Claims

1. A method for descaling the equalizing electrode of a converter valve, characterized in that, Using the aluminum radiator (4) in the converter valve as the cathode and each equalizing electrode (3) as the anode, the aluminum radiator (4) is connected to the negative terminal of the DC power generator (1), and each equalizing electrode (3) is connected in series to the positive terminal of the DC power generator (1), so that the DC power generator (1), the aluminum radiator (4), and the equalizing electrode (3) form an electrical circuit through the cooling water in the converter valve. The DC power generator (1) applies current to the electrical circuit, and the equalizing electrode (3) and the aluminum radiator (4) are used as electrodes to make the internal cooling water undergo an electrolytic reaction, thereby removing the scale on the equalizing electrode. The current applied to the electrical circuit by the DC power generator (1) is 4A to 6A. Before the DC power generator (1) applies current, the water circuit between the equalizing electrode (3) and the aluminum radiator (4) is replenished through the cooling water system in the converter valve to make the water circuit full of water. At the same time, the conductivity of the internal cooling water is controlled to be 50μs / cm to 100μs / cm by adding electrolyte NaCl.

2. The descaling method for the equalizing electrode of the converter valve according to claim 1, characterized in that, There are two aluminum heat sinks (4), and the two aluminum heat sinks (4) are connected in series and then connected to the negative terminal of the DC power generator (1).

3. The method for descaling the equalizing electrode of the converter valve according to any one of claims 1 to 2, characterized in that, The electrolysis time of the equalizing electrode (3) is 30 min to 60 min.

4. The descaling method for the equalizing electrode of the converter valve according to any one of claims 1 to 2, characterized in that, An ammeter (2) is installed in the electrical circuit to monitor the circuit current.

5. The method for descaling the equalizing electrode of the converter valve according to any one of claims 1 to 2, characterized in that, After the scale on the equalizing electrode (3) is dissolved, the internal cooling water in the internal cooling water system is replaced to meet the subsequent operation requirements of the converter valve.

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