Nuclear power plant generator hydrogen drying system and operation method thereof

Abstract

The invention relates to the technical field of nuclear power plant operation, in particular to a nuclear power plant generator hydrogen drying system and an operation method thereof.The system comprises a drying tower A, a drying tower B, a hydrogen cooler, a drying tower switching valve, a condenser and a steam trap, the drying tower A and the drying tower B are used for drying hydrogen, and the drying tower switching valve is arranged between the drying tower A and the drying tower B; the drying tower switching valve is connected in series with the hydrogen cooler and the condenser through a pipeline to form a closed loop; the hydrogen cooler is respectively connected into the conventional island closed cooling water system and the nuclear power plant chilled water production system through pipelines, and the hydrogen cooler is connected into the conventional island closed cooling water system and the nuclear power plant chilled water production system to provide cooling water for the hydrogen cooler and condense moisture in wet hydrogen in the hydrogen cooler. The generator hydrogen drying system is connected with a nuclear power plant chilled water production system, a standby cold source of the generator hydrogen drying system is added, and normal operation of the generator hydrogen drying system is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of nuclear power plant operation, and particularly to a hydrogen drying system for a nuclear power plant generator and an operation method thereof. Background Art

[0002] The hydrogen cooling device of the hydrogen drying system of a nuclear power unit generator needs to be cooled by the closed cooling water system of the conventional island. When the summer temperature is high, the supply water temperature of the closed cooling water system of the conventional island is maintained above 35°C for a long time. This results in insufficient cooling of the generator hydrogen drying system, low drying efficiency of the dryer, and inability to reduce the hydrogen dew point of the generator to the designed requirement value of -20°C. High hydrogen humidity will seriously affect the safe and stable operation of the generator, causing stress corrosion and wear of the generator rotor retaining ring, reducing the insulation electrical strength of the stator, and increasing the ventilation loss of the generator. At the same time, due to the low drying efficiency of the generator hydrogen drying system, the generator hydrogen drying system operates continuously for a long time, increasing the workload of the operating personnel and causing a large amount of waste of plant electricity.

[0003] In addition, the generator hydrogen drying system is only cooled by the closed cooling water system of the conventional island and has no emergency standby cold source, resulting in a problem of insufficient safety margin. In the case of a failure or maintenance of the closed cooling water system of the conventional island, the normal operation of the generator hydrogen drying system in an emergency cannot be guaranteed. Summary of the Invention

[0004] The present invention provides a hydrogen drying system for a nuclear power plant generator and an operation method thereof, which are used to solve the problems of insufficient cooling and lack of standby cold source in the existing generator hydrogen drying system.

[0005] The technical solution of the present invention is as follows:

[0006] The present invention provides a hydrogen drying system for a nuclear power plant generator, which system includes drying tower A, drying tower B, a hydrogen cooler, a drying tower switching valve, a condenser, the closed cooling water system of the conventional island, and the nuclear power plant chilled water production system. Drying tower A and drying tower B are used to dry hydrogen. A drying tower switching valve is provided between drying tower A and drying tower B. The drying tower switching valve is connected in series with the hydrogen cooler and the condenser through pipelines to form a closed loop; the hydrogen cooler is connected to the closed cooling water system of the conventional island and the nuclear power plant chilled water production system through pipelines, and connecting to the closed cooling water system of the conventional island and the nuclear power plant chilled water production system provides cooling water for the hydrogen cooler and condenses the moisture in the wet hydrogen in the hydrogen cooler.

[0007] In some embodiments, the condenser is connected to a steam trap through a pipeline. The condenser collects the condensed water generated by the hydrogen cooler, and the steam trap discharges the condensed water.

[0008] In some embodiments, the drying tower switching valve is connected to the hydrogen inlet and the hydrogen outlet through pipelines, and the drying tower switching valve controls the hydrogen to enter drying tower A or drying tower B for drying.

[0009] In some embodiments, the hydrogen outlet is sequentially connected to an instrument root valve and a dew point meter through pipelines, and the dew point meter is used to measure the moisture content of the output hydrogen.

[0010] In some embodiments, stop valve A and stop valve B are respectively provided at the inlet and outlet of the hydrogen cooler where the closed cooling water system of the conventional island is connected, and stop valve D and stop valve C are respectively provided at the inlet and outlet of the hydrogen cooler where the chilled water production system of the nuclear power plant is connected.

[0011] In some embodiments, the closed cooling water system of the conventional island uses seawater for cooling, and the cooling water temperature of the closed cooling water system of the conventional island changes with the seawater; the chilled water production system of the nuclear power plant is cooled by the principle of air-conditioning compression and expansion, and the chilled water temperature of the chilled water production system of the nuclear power plant is 5°C.

[0012] The present invention provides an operation method for a hydrogen drying system of a nuclear power plant generator, and the method includes:

[0013] One of drying tower A and drying tower B is used to adsorb the moisture in the hydrogen, and the other removes the absorbed moisture through the hydrogen cooler. The two operate alternately under the control of the drying tower switching valve; when the supply water temperature of the closed cooling water system of the conventional island is lower than 20°C, close stop valve C and stop valve D, open stop valve A and stop valve B, and use the closed cooling water system of the conventional island to cool the hydrogen cooler;

[0014] When the supply water temperature of the closed cooling water system of the conventional island is higher than 20°C, close stop valve A and stop valve B, open stop valve C and stop valve D, and use the chilled water production system of the nuclear power plant to cool the hydrogen cooler;

[0015] When the closed cooling water system of the conventional island fails or is under maintenance, close stop valve A and stop valve B, open stop valve C and stop valve D, and use the chilled water production system of the nuclear power plant to cool the hydrogen cooler.

[0016] In some embodiments, drying tower A and drying tower B alternate every 7.5 hours of operation, so that one drying tower is in the "adsorption operation" mode to adsorb the moisture in the hydrogen to reduce the water content in the generator hydrogen; the other drying tower is in the "regeneration operation" mode to remove the moisture in the drying tower to restore the moisture adsorption capacity of the drying tower; after 7.5 hours, the drying tower in the "adsorption operation" mode is automatically switched to the "regeneration operation" mode through the drying tower switching valve, and the drying tower in the "regeneration operation" mode is automatically switched to the "adsorption operation" mode.

[0017] In some embodiments, when the monitored value of the dew point meter reaches -20°C, the hydrogen drying system is shut down.

[0018] Implementing the present invention has the following beneficial effects:

[0019] The present invention provides a hydrogen drying system for a nuclear power plant generator and an operation method thereof. Implementing the present invention has the following advantages:

[0020] 1. In summer when it is hot, the present invention uses the direct cooling of the hydrogen drying system of the generator by the chilled water production of the nuclear power plant, which can reduce the dew point of the hydrogen in the generator to the design requirement value of -20°C, ensuring the generator operates under the best conditions. It reduces the operation workload of the operators and the frequency of inspection and monitoring, reduces the occupation of manpower and energy, and reduces the burden on the operators. At the same time, it avoids the waste of a large amount of plant electricity caused by the continuous operation of the hydrogen drying system of the generator, and also avoids the problem of shortening the service life of the dryer caused by the continuous operation of the hydrogen drying system of the generator, reducing the maintenance frequency of the hydrogen drying system of the generator.

[0021] 2. The present invention is connected to the chilled water production system of the nuclear power plant, adding an additional standby cold source for the hydrogen drying system of the generator, which can ensure the normal operation of the hydrogen drying system of the generator when the closed cooling water system of the conventional island fails or is under maintenance.

[0022] 3. The present invention uses the direct cooling of the hydrogen drying system of the generator by the chilled water production of the nuclear power plant. Since the chemical compositions and index requirements of the chilled water production system of the nuclear power plant and the closed cooling water system of the conventional island are the same, it avoids the corrosion problem of the hydrogen cooler. Description of the Drawings

[0023] Figure 1 Schematic diagram of a hydrogen drying system for a nuclear power plant generator proposed in an embodiment of the present invention;

[0024] Description of the Drawings: 1. Drying tower A; 2. Drying tower switching valve; 3. Drying tower B; 4. Steam trap; 5. Condenser; 6. Hydrogen flow regulating valve; 7. Hydrogen cooler; 8. Stop valve A; 9. Stop valve B; 10. Dew point meter; 11. Instrument root valve; 12. Stop valve C; 13. Stop valve D; 14. Hydrogen inlet; 15. Hydrogen outlet; 16. Inlet of the chilled water production system of the nuclear power plant; 17. Outlet of the chilled water production system of the nuclear power plant; 18. Inlet of the closed cooling water system of the conventional island; 19. Outlet of the closed cooling water system of the conventional island. Detailed Embodiments

[0025] The technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0026] As Figure 1 shown, the present invention provides a hydrogen drying system for a nuclear power plant generator, which system includes a hydrogen dryer, a closed cooling water system for the conventional island, and a chilled water production system for the nuclear power plant.

[0027] The closed cooling water system for the conventional island provides cooling water to the turbine-related equipment in the conventional island plant to ensure the normal operation of the turbine-related equipment. The closed cooling water system for the conventional island is cooled by seawater, and the heat of the turbine-related equipment is discharged into the seawater. The temperature of the cooling water provided by the closed cooling water system for the conventional island changes with the seawater temperature. In spring, autumn, and winter, cooling water below 20°C can be provided, and in summer, the temperature of the cooling water provided is higher than 20°C.

[0028] The chilled water production system for the nuclear power plant provides chilled water to the ventilation system in the conventional island plant and discharges the heat of the ventilation system in the conventional island plant into the atmosphere. The chilled water production system for the nuclear power plant is based on the principle of air-conditioning compression and expansion. The temperature of the chilled water provided by the chilled water production system for the nuclear power plant does not change with the season and can provide stable chilled water at 5°C.

[0029] The hydrogen dryer includes: drying tower A1, drying tower B3, hydrogen cooler 7, drying tower switching valve 2, condenser 5, and trap 4. Drying tower A1 and drying tower B3 are used to adsorb moisture in hydrogen. A drying tower switching valve 2 is provided between drying tower A1 and drying tower B3. The drying tower switching valve 2 switches drying tower A1 and drying tower B3 regularly (every 7.5 hours) so that one drying tower is in the "adsorption operation" mode to adsorb moisture in hydrogen to reduce the water content in the generator hydrogen; the other drying tower is in the "regeneration operation" mode to remove the moisture in the drying tower to restore the moisture adsorption capacity of the drying tower. The drying tower switching valve 2 is connected to the hydrogen inlet 14 and the hydrogen outlet 15 through pipelines. The drying tower switching valve 2 controls the hydrogen to enter drying tower A1 or drying tower B3 for drying. The hydrogen outlet 15 is connected to the instrument root valve 11 and the dew point meter 10 through pipelines in sequence. The instrument root valve 11 is used to isolate the dew point meter 10 for the maintenance of the dew point meter 10; the dew point meter 10 is used to measure the moisture of the output hydrogen. When the monitored value of the dew point meter 10 reaches -20°C, the hydrogen drying system is shut down.

[0030] The drying tower switching valve 2 is connected in series with the hydrogen cooler 7 and the condenser 5 through pipelines to form a closed loop. The hydrogen cooler 7 is connected to the conventional island closed cooling water system and the nuclear power plant chilled water production system through pipelines respectively. Connecting to the conventional island closed cooling water system and the nuclear power plant chilled water production system provides cooling water for the hydrogen cooler 7 and condenses the moisture in the wet hydrogen in the hydrogen cooler 7. At the inlet 18 of the conventional island closed cooling water system and the outlet 19 of the conventional island closed cooling water system where the conventional island closed cooling water system is connected to the hydrogen cooler 7, a stop valve A8 and a stop valve B9 are respectively provided. At the outlet 17 of the nuclear power plant chilled water production system and the inlet 16 of the nuclear power plant chilled water production system where the nuclear power plant chilled water production system is connected to the hydrogen cooler 7, a stop valve C12 and a stop valve D13 are respectively provided. The condenser 5 is connected to the steam trap 4 through a pipeline. The condenser 5 collects the condensed water generated by the hydrogen cooler 7, and the steam trap 4 discharges the condensed water.

[0031] As Figure 1 shown, the present invention includes two drying towers: drying tower A1 and drying tower B3. During normal operation, one drying tower is in the "adsorption operation" mode, and the other drying tower is in the "regeneration operation" mode.

[0032] When the drying tower A1 is in the "adsorption operation" mode, the drying tower A1 is connected to the hydrogen inlet 14 and the hydrogen outlet 15. The hydrogen in the generator enters the drying tower A1, and the drying tower A1 adsorbs the moisture in the hydrogen. The dried hydrogen returns to the generator, and so on, cycling the "adsorption operation" for 7.5 hours.

[0033] When the drying tower A1 is in the "adsorption operation" mode, the drying tower B3 is in the "regeneration operation" mode. At this time, the drying tower B3 is not connected to the generator, and the drying tower B3 is connected to the hydrogen cooler 7. Hydrogen forms a closed-loop flow between the drying tower B3 and the hydrogen cooler 7. After the wet hydrogen containing moisture comes out of the drying tower B3, it passes through the hydrogen cooler 7, cooling the gaseous moisture into liquid condensed water. The condenser 5 collects the condensed water and discharges the condensed water through the steam trap 4. The hydrogen returns to the drying tower B3 again, and so on, cycling the "regeneration operation" for 7.5 hours to remove the moisture in the drying tower B3, thereby restoring the moisture adsorption capacity of the drying tower B3.

[0034] After 7.5 hours, it is automatically switched through the drying tower switching valve 2 so that the drying tower B3 is in the "adsorption operation" mode and the drying tower A1 is in the "regeneration operation" mode. Each 7.5 hours is a cycle period. In this way, one drying tower is in the "adsorption operation" mode to adsorb the moisture in the hydrogen to reduce the water content in the generator hydrogen; the other drying tower is in the "regeneration operation" mode to remove the moisture in the drying tower to restore the moisture adsorption capacity of the drying tower. When the monitored value of the dew point meter 10 reaches -20°C, the generator hydrogen drying system is shut down.

[0035] The present invention provides an operation method for a hydrogen drying system of a generator in a nuclear power plant, and the method includes:

[0036] One of drying tower A1 and drying tower B3 is used to adsorb moisture in hydrogen, and the other removes the absorbed moisture through hydrogen cooler 7. The two are controlled to operate alternately through drying tower switching valve 2; when the supply water temperature of the closed cooling water system in the conventional island is lower than 20°C, shut off valve C12 and valve D13, open valve A8 and valve B9, and use the closed cooling water system in the conventional island to cool hydrogen cooler 7;

[0037] When the supply water temperature of the closed cooling water system in the conventional island is higher than 20°C, shut off valve A8 and valve B9, open valve C12 and valve D13, and use the chilled water production system in the nuclear power plant to cool hydrogen cooler 7;

[0038] When the closed cooling water system in the conventional island fails or is under maintenance, shut off valve A8 and valve B9, open valve C12 and valve D13, and use the chilled water production system in the nuclear power plant to cool hydrogen cooler 7.

[0039] In the present invention, the water quality of the chilled water production system in the nuclear power plant is exactly the same as that of the closed cooling water system in the conventional island, and it can meet the anti-corrosion requirements of hydrogen cooler 7. The water quality parameters are shown in the following table.

[0040] Parameter Unit Closed Cooling Water in Conventional Island Chilled Water Production in Nuclear Power Plant pH 8.5-10.5 8.5-10.5 Nitrite mg / kg 200-1000 200-1000 Fluoride mg / kg ＜1.0 ＜1.0 Iron mg / kg ＜1.0 ＜1.0 Copper mg / kg ＜0.5 ＜0.5 TTA mg / kg 5-100 5-100

[0041] Specific embodiments: 1. Operating mode of the generator hydrogen drying system in low-temperature weather

[0042] When the supply water temperature of the closed cooling water system in the conventional island is lower than 20°C, maintain the original designed operation mode of the generator hydrogen drying system, shut off valve C12 and valve D13, open valve A8 and valve B9, and cool hydrogen cooler 7 through the closed cooling water system in the conventional island.

[0043] 2. Operating mode of the generator hydrogen drying system in high-temperature weather

[0044] As the temperature rises, when the supply water temperature of the closed cooling water system in the conventional island is higher than 20°C, shut off valve A8 and valve B9, open valve C12 and valve D13, and cool hydrogen cooler 7 through the chilled water production system in the nuclear power plant, which can ensure that the wet hydrogen in the drying tower in the "regenerative operation" mode is fully cooled, thereby restoring the moisture adsorption capacity of the drying tower.

[0045] 3. Operating mode of generator hydrogen drying when the closed cooling water system in the conventional island fails or is under maintenance

[0046] When the closed cooling water system of the conventional island fails or is under maintenance and cannot supply cooling water to the generator hydrogen drying system, close the stop valve A8 and the stop valve B9, and open the stop valve C12 and the stop valve D13 to cool the hydrogen cooler 7 through the nuclear power plant chilled water production system to maintain the normal operation of the hydrogen drying system.

[0047] The above embodiments only express several implementation manners of the present invention, and the description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the appended claims.

Claims

1. A hydrogen drying system for a nuclear power plant generator, characterized in that: The hydrogen drying system comprises a drying tower A, a drying tower B, a hydrogen cooler, a drying tower switching valve, a condenser, a conventional island closed cooling water system and a nuclear power plant chilled water production system. The drying tower A and the drying tower B are used to dry hydrogen. A drying tower switching valve is arranged between the drying tower A and the drying tower B. The drying tower switching valve is connected in series with the hydrogen cooler and the condenser through a pipeline to form a closed loop. The hydrogen cooler is respectively connected to the conventional island closed cooling water system and the nuclear power plant chilled water production system through pipelines. The connection to the conventional island closed cooling water system and the nuclear power plant chilled water production system provides cooling water for the hydrogen cooler and condenses moisture in the wet hydrogen in the hydrogen cooler.

2. A hydrogen drying system for a nuclear power plant generator according to claim 1, characterized in that: The condenser is connected to a steam trap through a pipeline. The condenser collects condensed water generated by the hydrogen cooler, and the steam trap discharges the condensed water.

3. A hydrogen drying system for a nuclear power plant generator according to claim 2, characterized in that: The drying tower switching valve connects the hydrogen inlet and the hydrogen outlet through a pipeline, and the drying tower switching valve controls the hydrogen to enter the drying tower A or the drying tower B for drying.

4. A hydrogen drying system for a nuclear power plant generator according to claim 3, characterized in that: The hydrogen outlet is connected to an instrument root valve and a dew point meter in sequence through a pipeline, and the dew point meter is used to measure the moisture content of the output hydrogen.

5. A hydrogen drying system for a nuclear power plant generator according to claim 4, characterized in that: The inlet and outlet of the conventional island closed cooling water system connected to the hydrogen cooler are respectively provided with a stop valve A and a stop valve B, and the inlet and outlet of the nuclear power plant chilled water production system connected to the hydrogen cooler are respectively provided with a stop valve D and a stop valve C.

6. A nuclear power plant generator hydrogen drying system according to claim 1, characterized in that: The conventional island closed cooling water system is cooled by seawater, and the cooling water temperature of the conventional island closed cooling water system varies with the seawater; the nuclear power plant chilled water production system is cooled by the air conditioning compression and expansion principle, and the chilled water temperature of the nuclear power plant chilled water production system is 5°C.

7. An operating method of a hydrogen drying system for a nuclear power plant generator as claimed in any one of claims 1 to 6, characterized in that: The operation method comprises: The drying tower A and the drying tower B are used to absorb moisture in hydrogen, and the other one removes the absorbed moisture through the hydrogen cooler. The two are controlled to operate alternately by the drying tower switching valve; when the water supply temperature of the conventional island closed cooling water system is lower than 20°C, the stop valve C and the stop valve D are closed, the stop valve A and the stop valve B are opened, and the conventional island closed cooling water system is used to cool the hydrogen cooler; When the water supply temperature of the conventional island closed cooling water system is higher than 20°C, the stop valve A and the stop valve B are closed, the stop valve C and the stop valve D are opened, and the nuclear power plant chilled water production system is used to cool the hydrogen cooler; When the conventional island closed cooling water system fails or is under maintenance, the stop valve A and the stop valve B are closed, the stop valve C and the stop valve D are opened, and the nuclear power plant chilled water production system is used to cool the hydrogen cooler.

8. The method for operating a hydrogen drying system for a nuclear power plant generator according to claim 7, characterized in that: The drying tower A and the drying tower B work alternately every 7.5 hours, so that one drying tower is in the "adsorption operation" mode to absorb moisture in the hydrogen to reduce the water content in the hydrogen of the generator; the other drying tower is in the "regeneration operation" mode to remove moisture in the drying tower to restore the moisture adsorption capacity of the drying tower; after 7.5 hours, the drying tower in the "adsorption operation" mode is automatically switched to the "regeneration operation" mode through the drying tower switching valve, and the drying tower in the "regeneration operation" mode is automatically switched to the "adsorption operation" mode.

9. The method for operating a hydrogen drying system for a nuclear power plant generator according to claim 7, characterized in that: When the value monitored by the dew point meter reaches -20°C, the hydrogen drying system is shut down.

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