Method and device for controlling the quality of cooling water in a converter valve

Abstract

The application discloses a kind of cooling water quality control method and device in converter valve, the method first uses EDI module bypass processing cooling water in converter valve, the water obtained is sent back to cooling water tank in converter valve, the concentrated water and polar water obtained are sent to circulating water tank, then degassing is carried out through degassing device, and the cooling water after degassing is processed through ion exchanger, and the deionized cooling water after processing is sent to EDI module, to obtain qualified EDI water.The device includes cooling water tank in converter valve, EDI module, circulating water tank, degassing device and ion exchanger.The method and device of the application can remove impurities in cooling water in converter valve, stabilize the quality of cooling water, solve the problems such as replacement during ion exchange resin cannot operate, cannot be flushed to ensure water quality during initial operation, and the influence of ion exchange resin eluate on water quality, and meet the zero discharge demand of cooling water, which can effectively improve the operation reliability and economy of cooling water system in converter station.

Description

Technical Field

[0001] This invention belongs to the field of cooling water treatment in converter valves, and specifically relates to a method and device for controlling the water quality of cooling water in converter valves. Background Technology

[0002] With the continuous development of the power system 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. The internal cooling water system of the converter valve typically uses deionized water as the cooling medium, and the water quality requirements are extremely strict to prevent corrosion and scaling that could cause equipment failure. According to incomplete statistics, from 2015 to 2021, failures caused by the internal cooling water system accounted for more than 45% of converter station failures. Therefore, how to effectively control the water quality of the internal cooling water, improve the reliability of water quality control, and reduce the problem of metal scaling in the internal cooling water system urgently needs to be addressed.

[0003] Currently, the cooling water system inside the converter valve usually uses the bypass ion exchange resin method to purify the internal cooling water quality. This method has the following main disadvantages: (1) The service life of the ion exchange resin is relatively short and it needs to be replaced regularly. However, since the cooling water system inside the converter valve does not have a demineralized water replenishment system, during the operation of the converter valve, in order to prevent water quality deterioration or accidents, it is not allowed to carry out the corresponding ion exchange resin replacement and maintenance work. It can only be replaced in conjunction with the annual maintenance, resulting in the replacement of the ion exchange resin before it expires or the replacement is not timely, leading to high maintenance costs or potential hazards; (2) The operation and commissioning of the ion exchange resin requires rinsing to remove impurities and resin powder. However, the cooling water system inside the converter valve does not have an additional water system for rinsing. Direct operation can easily lead to poor initial water quality, and foreign matter precipitated from the ion exchange resin enters the cooling water system inside the converter valve; (3) During the operation of the ion exchange resin, there is precipitation of impurities such as organic matter and ions, which affects water quality and accelerates the corrosion of metal materials. Some scholars have proposed using one or more of EDI and reverse osmosis systems as internal cooling water treatment systems. However, these systems have the following drawbacks: firstly, the discharge of concentrated water requires a large amount of internal cooling water replenishment, resulting in water waste and increased operation and maintenance costs; secondly, the converter valve is not designed with a demineralized water replenishment system, making it unsuitable for existing valve cooling systems. Therefore, a new method for controlling the cooling water quality within the converter valve is needed to replace existing technologies. 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 method and device for controlling the cooling water quality inside the converter valve. The method and device can remove impurities from the cooling water inside the converter valve, stabilize the cooling water quality, and solve problems such as the inability to replace ion exchange resin during operation, the inability to flush and ensure water quality in the initial stage of operation, and the impact of ion exchange resin leaching on water quality. At the same time, it meets the zero discharge requirement of the cooling water, and can effectively improve the reliability and economy of the cooling water system in the converter station.

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

[0006] A method for controlling the cooling water quality inside a converter valve involves first using an EDI module to bypass and treat the cooling water inside the converter valve, then returning the product water from the EDI module to the cooling water tank inside the converter valve, sending the concentrate and electrode water from the EDI module to a circulating water tank, degassing the mixed water in the circulating water tank using a degassing device, and then treating the degassed cooling water with an ion exchanger. The resulting deionized cooling water is then sent back to the EDI module for further treatment to obtain qualified EDI product water.

[0007] In the above-mentioned method for controlling the cooling water quality in the converter valve, preferably, the resistivity of the water produced by the EDI module is ≥18MΩ·cm.

[0008] In the above-mentioned method for controlling the cooling water quality in the converter valve, preferably, the content of each gas in the internal cooling water after treatment by the degassing device is less than 2 ppb.

[0009] In the above-mentioned method for controlling the cooling water quality in the converter valve, preferably, the degassing device is provided with a degassing membrane, which is a gas-liquid separation membrane with a degassing efficiency greater than 99.99%.

[0010] In the above-mentioned method for controlling the cooling water quality in the converter valve, preferably, the ion exchanger is a mixed bed composed of hydrogen-oxygen anion exchange resin and hydrogen-type cation exchange resin.

[0011] As a general technical concept, the present invention also provides a cooling water quality control device for a converter valve, including a cooling water tank inside the converter valve, an EDI module, a circulating water tank, a degassing device, and an ion exchanger. The EDI module is provided with a first inlet, a second inlet, a product water outlet, an electrode water outlet, and a concentrate outlet. The outlet of the cooling water tank inside the converter valve is connected to the first inlet of the EDI module. The product water outlet of the EDI module is connected to the return water outlet of the cooling water tank inside the converter valve. The electrode water outlet and the concentrate outlet of the EDI module are respectively connected to the inlet of the circulating water tank. The outlet of the circulating water tank, the degassing membrane, the ion exchanger, and the second inlet of the EDI module are connected in sequence.

[0012] Preferably, in the above-mentioned cooling water quality control device for the converter valve, a water supply pump and a valve are provided between the outlet of the cooling water tank inside the converter valve and the first inlet of the EDI module, between the outlet of the circulating water tank and the degassing device, and between the ion exchanger and the second inlet of the EDI module.

[0013] Preferably, in the above-mentioned cooling water quality control device for the converter valve, the degassing device is provided with an exhaust port, which is connected to a vacuum pump.

[0014] Preferably, in the aforementioned cooling water quality control device for the converter valve, valves are provided on the pipes between the product water outlet of the EDI module and the return water outlet of the cold water tank inside the converter valve, the pipes between the concentrate outlet of the EDI module and the inlet of the circulating water tank, the pipes between the electrode water outlet of the EDI module and the inlet of the circulating water tank, and the pipes between the degassing device and the ion exchanger.

[0015] Preferably, in the aforementioned cooling water quality control device for the converter valve, there are two ion exchangers arranged side by side.

[0016] In this invention, EDI (Electro-deionization, continuous electro-desalination technology) is a pure water production technology that combines ion exchange technology, ion exchange membrane technology, and ion electromigration technology. It combines electrodialysis and ion exchange technology, using high voltage at both ends of the electrodes to move charged ions in the water, and using ion exchange resin and selective resin membrane to accelerate ion movement and removal, thereby achieving the purpose of water purification.

[0017] Compared with the prior art, the advantages of the present invention are as follows:

[0018] The method and apparatus of this invention use an EDI module to treat the cooling water inside the converter valve, and employ a degassing device (degassing membrane) and an ion exchanger to jointly treat the concentrate and electrode water generated during EDI operation. EDI treatment ensures stable and reliable cooling water quality within the valve, with a long maintenance cycle. The combined treatment of EDI concentrate and electrode water by the degassing device and ion exchanger allows for the complete recovery of the concentrate and electrode water generated during the EDI process, achieving zero discharge of cooling water from the converter valve. Compared to traditional ion exchange resin methods, the problems of impurities and leachates in ion exchange resin affecting the cooling water quality inside the converter valve, short maintenance cycles, high operation and maintenance costs, and poor water quality in the initial stage of operation are eliminated. The method and apparatus of this invention offer advantages such as stable water quality, long maintenance cycles, and reliable operation. Compared to traditional EDI or membrane treatment technologies, this invention eliminates the need for wastewater discharge, achieving zero discharge of internal cooling water. In summary, this invention features superior water quality, higher operational reliability, and excellent economic efficiency. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the water circuit of the cooling water quality control device inside the converter valve in Embodiment 1 of the present invention.

[0020] Legend:

[0021] 1. EDI module; 2. Cold water tank inside the converter valve; 3. Circulating water tank; 4. Degassing device; 5. Ion exchanger; 6. Feed water pump; 7. Valves; 8. Vacuum pump. Detailed Implementation

[0022] 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.

[0023] Example 1

[0024] A method for controlling the cooling water quality inside a converter valve according to the present invention includes the following steps: firstly, the cooling water inside the converter valve is treated by bypassing the EDI module 1, the product water of the EDI module 1 is sent back to the cooling water tank 2 inside the converter valve, the concentrate and electrode water of the EDI module 1 are sent to a circulating water tank 3, the mixed water in the circulating water tank 3 is degassed by a degassing device 4, the degassed cooling water is treated by ion exchanger 5, and the resulting deionized cooling water is sent back to the EDI module 1 for further treatment to obtain qualified EDI product water, thereby achieving zero discharge of cooling water inside the converter valve.

[0025] In this embodiment, EDI module 1 is a Siemens IP-LXM 45Z EDI module with a water resistivity of 18 MΩ·cm.

[0026] In this embodiment, the oxygen, carbon dioxide and other gas contents in the internal cooling water after treatment by the degassing device 4 are all less than 2 ppb.

[0027] In this embodiment, the degassing device 4 is equipped with a degassing membrane, which is a hollow fiber polypropylene gas-liquid separation membrane with a degassing efficiency of 99.999%.

[0028] In this embodiment, the ion exchanger 5 is a mixed bed composed of hydrogen-oxygen anion exchange resin and hydrogen-type cation exchange resin.

[0029] In this embodiment, the circulating water tank 3 is equipped with a stirrer.

[0030] A cooling water quality control device for a converter valve according to the present invention includes a converter valve internal cooling water tank 2, an EDI module 1, a circulating water tank 3, a degassing device 4, and an ion exchanger 5. The EDI module 1 is provided with a first inlet, a second inlet, a product water outlet, an electrode water outlet, and a concentrate outlet. The outlet of the converter valve internal cooling water tank 2 is connected to the first inlet of the EDI module 1. The product water outlet of the EDI module 1 is connected to the return water outlet of the converter valve internal cooling water tank 2. The electrode water outlet and the concentrate outlet of the EDI module 1 are respectively connected to the inlet of the circulating water tank 3. The outlet of the circulating water tank 3, the degassing membrane 4, the ion exchanger 5, and the second inlet of the EDI module 1 are connected in sequence.

[0031] In this embodiment, a water pump 6 and a valve 7 are provided between the outlet of the cold water tank 2 inside the converter valve and the first inlet of the EDI module 1, between the outlet of the circulating water tank 3 and the degassing device 4, and between the ion exchanger 5 and the second inlet of the EDI module 1.

[0032] In this embodiment, the degassing device 4 is provided with an exhaust port, which is connected to a vacuum pump 8.

[0033] In this embodiment, the above-mentioned components can be connected by pipes. Valves 7 are provided on the pipes between the product water outlet of EDI module 1 and the return water inlet of the cold water tank 2 inside the converter valve, the pipes between the concentrate outlet of EDI module 1 and the inlet of the circulating water tank 3, the pipes between the electrode water outlet of EDI module 1 and the inlet of the circulating water tank 3, and the pipes between the degassing device 4 and the ion exchanger 5.

[0034] In this embodiment, there are two ion exchangers 5, which are arranged side by side, one for standby and one for use.

[0035] The working principle and workflow of the device in this embodiment are as follows, and its water circuit flow diagram is shown below. Figure 1 As shown:

[0036] EDI module 1 bypasses the cooling water in the internal cooling water tank 2 (hereinafter referred to as the internal cooling water tank) of the converter valve to obtain qualified EDI permeate water. The EDI permeate water returns to the internal cooling water tank, completing the treatment of the internal cooling water of the converter valve. EDI concentrate and electrode water enter the circulating water tank 3. The mixed water in the circulating water tank 3 is first degassed by a degassing device 4 containing a degassing membrane. After degassing, it is treated by an ion exchanger 5 and then reused to enter EDI module 1 for further treatment to obtain qualified EDI permeate water.

[0037] In the above embodiments, the method and apparatus of the present invention can purify the converter valves in the converter station, so that the internal cooling water quality meets the requirements, while achieving zero discharge of internal cooling water, making operation and maintenance more intelligent, and reducing the workload and cost of operation and maintenance.

[0038] 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 controlling the cooling water quality inside a converter valve, characterized in that, First, the EDI module (1) is used to bypass the cooling water inside the converter valve. The product water of the EDI module (1) is sent back to the cooling water tank (2) inside the converter valve. The concentrate and electrode water of the EDI module (1) are sent to a circulating water tank (3). The mixed water in the circulating water tank (3) is degassed by a degassing device (4). The degassed internal cooling water is ion exchanged by an ion exchanger (5). The resulting deionized internal cooling water is sent to the EDI module (1) for further processing to obtain qualified EDI product water. The water resistivity of the EDI module (1) is ≥18 MΩ·cm; The content of each gas in the internal cooling water after treatment by the degassing device (4) is less than 2 ppb; The ion exchanger (5) is a mixed bed composed of hydrogen-oxygen anion exchange resin and hydrogen-type cation exchange resin. The degassing device (4) is equipped with a degassing membrane, which is a gas-liquid separation membrane with a degassing efficiency greater than 99.99%.

2. A device for controlling the cooling water quality inside a converter valve, characterized in that, The system includes a cold water tank (2) inside a converter valve, an EDI module (1), a circulating water tank (3), a degassing device (4), and an ion exchanger (5). The EDI module (1) is provided with a first inlet, a second inlet, a product water outlet, an electrode water outlet, and a concentrate water outlet. The outlet of the cold water tank (2) inside the converter valve is connected to the first inlet of the EDI module (1). The product water outlet of the EDI module (1) is connected to the return water outlet of the cold water tank (2) inside the converter valve. The electrode water outlet and the concentrate water outlet of the EDI module (1) are respectively connected to the inlet of the circulating water tank (3). The outlet of the circulating water tank (3), the degassing device (4), the ion exchanger (5), and the second inlet of the EDI module (1) are connected in sequence.

3. The cooling water quality control device for the converter valve according to claim 2, characterized in that, A water pump (6) and a valve (7) are provided between the outlet of the cold water tank (2) inside the converter valve and the first inlet of the EDI module (1), between the outlet of the circulating water tank (3) and the degassing device (4), and between the ion exchanger (5) and the second inlet of the EDI module (1).

4. The cooling water quality control device for the converter valve according to claim 2 or 3, characterized in that, The degassing device (4) is provided with an exhaust port, which is connected to a vacuum pump (8).

5. The cooling water quality control device for the converter valve according to claim 2 or 3, characterized in that, Valves (7) are provided on the pipe between the product water outlet of the EDI module (1) and the return water inlet of the cold water tank (2) inside the converter valve, on the pipe between the concentrate outlet of the EDI module (1) and the inlet of the circulating water tank (3), on the pipe between the electrode water outlet of the EDI module (1) and the inlet of the circulating water tank (3), and on the pipe between the degassing device (4) and the ion exchanger (5).

6. The cooling water quality control device for the converter valve according to claim 2 or 3, characterized in that, The ion exchanger (5) is provided in two, and the two ion exchangers (5) are arranged side by side.

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