Demineralized Water Production and Deoxygenation System and Control Methods during the Initial Start-up Phase of a Nuclear Power Plant

Abstract

This invention belongs to the field of nuclear power industry technology, specifically relating to the demineralized water production and deoxygenation system and control method during the initial start-up phase of a nuclear power plant. The system includes a clean water pump, a clean water pump and a clean water pump outlet manual valve connected by a pipeline, a clean water pump outlet manual valve and an activated carbon filter connected by a pipeline, an activated carbon filter and a cation exchange bed connected by a pipeline, a cation exchange bed and a vacuum degassing tower level regulating valve connected by a pipeline, a vacuum degassing tower level regulating valve and a vacuum degassing tower connected by a pipeline, a vacuum degassing tower and an intermediate water pump connected by a pipeline, an intermediate water pump and an intermediate water pump outlet valve connected by a pipeline, an intermediate water pump outlet valve and an anion exchange bed connected by a pipeline, an anion exchange bed and a first regeneration air pressure isolation valve connected by a pipeline, an anion exchange bed and a mixed bed connected by a pipeline, a mixed bed and a second regeneration air pressure isolation valve connected by a pipeline, a mixed bed and a primary loop inlet water supply valve connected by a pipeline, a primary loop inlet water supply valve and a primary loop water supply tank connected by a pipeline, a primary loop water supply tank and a primary loop water supply outlet valve connected by a pipeline, and a primary loop water supply outlet valve and a primary loop water supply pump connected by a pipeline. The beneficial effects of this invention are as follows: by modifying the facilities and changing the operation mode of the original demineralized water production system, the system can achieve fully automatic and stable production of deoxygenated water, solving the problem of not being able to provide a large amount of deoxygenated water during the initial start-up.

Description

Technical Field

[0001] This invention belongs to the field of nuclear power industry technology, specifically relating to the demineralized water production and deoxygenation system and control method during the initial start-up phase of a nuclear power plant. Background Technology

[0002] The demineralized water production system can provide demineralized water as makeup water for the entire plant. The demineralized water is produced by passing clean water through an activated carbon filter to remove organic matter and free oxygen before entering a cation exchange bed. The cation exchange bed then removes cations such as calcium, magnesium, and sodium ions. Next, a vacuum degassing tower removes air from the water. Then, an anion exchange bed removes anions such as silica, silver sulfate, and chloride ions. Finally, a mixed bed further refines the water, followed by various ion exchangers. The resulting demineralized water is stored in demineralized water tanks. Two 1000-cubic-meter demineralized water tanks are provided for the conventional island, and one 400-cubic-meter primary loop makeup water tank is provided for the nuclear island. During the initial startup phase of the nuclear power plant, the primary loop requires a large amount of deoxygenated water, which is obtained by deoxygenating the demineralized water. However, the deoxygenated water production system of the nuclear island is designed to only supplement deoxygenated water during the normal operation of the primary loop, resulting in a small amount of deoxygenated water produced by the system. Therefore, the demineralized water production system needs to be modified to enable it to produce deoxygenated water in order to meet the deoxygenated water requirements of the primary loop during the initial startup phase. Summary of the Invention

[0003] The purpose of this invention is to provide a demineralized water production system and control method for the initial startup phase of a nuclear power plant. By adding pipelines and a primary loop makeup water bypass valve to the demineralized water production system and changing the system's operating mode, the system can produce a sufficient amount of deoxygenated water to meet the primary loop's deoxygenated water requirements during the initial startup phase.

[0004] The technical solution of this invention is as follows: A demineralized water to deoxygenated water system for the initial startup phase of a nuclear power plant includes a clean water pump. The clean water pump and its outlet manual valve are connected via pipelines. The clean water pump outlet manual valve and an activated carbon filter are connected via pipelines. The activated carbon filter and a cation exchange bed are connected via pipelines. The cation exchange bed and a vacuum degassing tower level regulating valve are connected via pipelines. The vacuum degassing tower level regulating valve and the vacuum degassing tower are connected via pipelines. The vacuum degassing tower and an intermediate water pump are connected via pipelines. The intermediate water pump and its outlet valve are connected via pipelines. The intermediate water pump outlet valve and anion exchange bed are connected via pipelines. The anion exchange bed and a first regeneration air pressure isolation valve are connected via pipelines. The anion exchange bed and a mixed bed are connected via pipelines. The mixed bed and a second regeneration air pressure isolation valve are connected via pipelines. The mixed bed and a primary loop inlet water supply valve are connected via pipelines. The primary loop inlet water supply valve and a primary loop water supply tank are connected via pipelines. The primary loop water supply tank and a primary loop water supply outlet valve are connected via pipelines. The primary loop water supply outlet valve and a primary loop water supply pump are connected via pipelines.

[0005] A first bypass pipe is added between the mixed bed and the primary inlet valve.

[0006] A second bypass pipe is added between the primary circuit outlet valve and the primary circuit make-up water pump.

[0007] The first bypass pipe and the second bypass pipe are connected by a primary water supply bypass valve.

[0008] The first regeneration air pressure isolation valve and the second regeneration air pressure isolation valve are pneumatic diaphragm valves.

[0009] The first bypass pipe is 2 meters long and has an inner diameter of 125 millimeters.

[0010] The second bypass pipe is 2 meters long and has an inner diameter of 125 millimeters.

[0011] The control methods for the demineralized water to deoxygenated water system during the initial startup phase of a nuclear power plant include the following steps:

[0012] Step 1: Before the system produces deoxygenated water, completely close the primary loop inlet valve and the primary loop outlet valve, and open the primary loop makeup water bypass valve so that the produced deoxygenated water enters the primary loop makeup water system directly without passing through the primary loop makeup water tank.

[0013] Step 2: During the deoxygenation process of the system, set the first regeneration air pressure isolation valve and the second regeneration air pressure isolation valve to manual mode. After manually closing the valves, manually tighten the handwheel to ensure that compressed air does not enter the anion bed and mixed bed.

[0014] Step 3: During the deoxygenation process of the system, do not start the primary loop water supply pump, start the intermediate water pump normally, the flow rate of the intermediate water pump is 20 to 30 cubic meters per hour, adjust the manual valve of the clean water pump outlet so that the vacuum degassing tower liquid level regulating valve is automatically adjusted within the effective characteristic range; so that the flow rate of the clean water pump is equivalent to the flow rate of the intermediate water pump.

[0015] The beneficial effects of this invention are as follows: by modifying the facilities and changing the operation mode of the original demineralized water production system, the system achieves fully automatic and stable deoxygenated water production, solving the problem of not being able to provide a large amount of deoxygenated water during the initial start-up. The modifications to the original demineralized water production system are minimal, saving on labor and system operating costs. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the demineralized water to deoxygenated water system provided by the present invention for the initial startup phase of a nuclear power plant.

[0017] In the diagram: 1. Clean water pump, 2. Clean water pump outlet manual valve, 3. Activated carbon filter, 4. Cation bed, 5. Vacuum degassing tower level regulating valve, 6. Vacuum degassing tower, 7. Intermediate water pump, 8. Intermediate water pump outlet valve, 9. Anion bed, 10. Mixed bed, 11-1. First regeneration compressed air isolation valve, 11-2. Second regeneration compressed air isolation valve, 12. Primary loop makeup water inlet valve, 13. Primary loop makeup water tank, 14. Primary loop makeup water outlet valve, 15. Primary loop makeup water pump, 16. Second bypass pipeline, 17. Primary loop makeup water bypass valve, 18. First bypass pipeline.

[0018] Please enlarge the image, and it would be best to change it to two lines so that the components and labels can be displayed more clearly. Detailed Implementation

[0019] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0020] To produce sufficient deoxygenated water, the existing demineralized water production system needs to be technically upgraded. The technical solutions include adding temporary facilities and temporarily changing the operating mode.

[0021] The demineralized water to deoxygenated water system during the initial startup phase of a nuclear power plant includes a clean water pump 1. Clean water pump 1 and its outlet manual valve 2 are connected via pipelines. The outlet manual valve 2 is connected to an activated carbon filter 3 via a pipeline. The activated carbon filter 3 is connected to a cation bed 4 via a pipeline. The cation bed 4 is connected to a vacuum degassing tower level regulating valve 5 via a pipeline. The vacuum degassing tower level regulating valve 5 is connected to a vacuum degassing tower 6 via a pipeline. The vacuum degassing tower 6 is connected to an intermediate water pump 7 via a pipeline. The intermediate water pump 7 is connected to an intermediate water pump outlet valve 8 via a pipeline. The outlet valve 8 of the intermediate water pump and the anion bed 9 are connected by a pipeline. The anion bed 9 is connected to the first regeneration air pressure isolation valve 11-1. The anion bed 9 is connected to the mixed bed 10 by a pipeline. The mixed bed 10 is connected to the second regeneration air pressure isolation valve 11-2. The mixed bed 10 is connected to the primary circuit inlet water supply valve 12 by a pipeline. The primary circuit inlet water supply valve 12 is connected to the primary circuit water supply tank 13 by a pipeline. The primary circuit water supply tank 13 is connected to the primary circuit water supply outlet valve 14 by a pipeline. The primary circuit water supply outlet valve 14 is connected to the primary circuit water supply pump 15 by a pipeline.

[0022] A first bypass pipe 18 is added between the mixed bed 10 and the primary loop inlet valve 12, and a second bypass pipe 16 is added between the primary loop outlet valve 14 and the primary loop makeup water pump 15. The first bypass pipe 18 and the second bypass pipe 16 are connected by a primary loop makeup water bypass valve 17. The first regeneration pneumatic isolation valve 11-1 and the second regeneration pneumatic isolation valve 11-2 are pneumatic diaphragm valves. The first bypass pipe 18 and the second bypass pipe 16 have a total length of 2 meters and an inner diameter of 125 millimeters.

[0023] The control methods for the demineralized water to deoxygenated water system during the initial startup phase of a nuclear power plant include the following steps:

[0024] Step 1: Before the system produces deoxygenated water, completely close the primary loop inlet valve 12 and the primary loop outlet valve 14, and open the primary loop makeup water bypass valve 17 so that the produced deoxygenated water enters the primary loop makeup water system directly without passing through the primary loop makeup water tank 13, thus avoiding secondary pollution of the produced deoxygenated water in the primary loop makeup water tank.

[0025] Step 2: The first regeneration air pressure isolation valve 11-1 and the second regeneration air pressure isolation valve 11-2 are pneumatic diaphragm valves. Instrument compressed air (0.65 MPa) may enter the anion bed and mixed bed, causing excessively high oxygen content in the deoxygenated water. During the system's deoxygenated water production process, put the first regeneration air pressure isolation valve 11-1 and the second regeneration air pressure isolation valve 11-2 into manual mode. After manually closing the valves, manually tighten the handwheel to ensure that compressed air does not enter the anion bed 9 and the mixed bed 10.

[0026] Step 3: During the deoxygenation process, do not start the primary loop makeup water pump 15 to prevent local negative pressure at the inlet of the primary loop makeup water pump, which could cause air to enter the pipeline; start the intermediate water pump 7 normally, with a flow rate of approximately 20 to 30 cubic meters per hour. If necessary, adjust the opening of the outlet valve of the intermediate water pump 8 to ensure that the internal pressure of the anion bed 9 and the mixed bed 10 does not exceed the design pressure (0.6 MPa); adjust the manual valve 2 at the outlet of the clear water pump, with a flow rate of approximately 40 cubic meters per hour, so that the vacuum degassing tower level regulating valve 5 can automatically adjust within its effective characteristic range; modify the minimum opening of the vacuum degassing tower level regulating valve 5 from 30% to 10% and set it to automatic mode, so that the flow rate of the clear water pump 1 drops to 20 to 30 cubic meters per hour, which is equivalent to the flow rate of the intermediate water pump 7, allowing the vacuum degassing tower to automatically produce deoxygenated water with a balanced flow rate.

[0027] This invention adds a connecting pipe and a bypass isolation valve between the inlet and outlet pipes of the primary loop makeup water tank, bypassing the primary loop makeup water tank and directly sending deoxygenated water into the primary loop makeup water system, thus avoiding secondary pollution of the deoxygenated water in the primary loop makeup water tank.

[0028] This invention closes the regeneration air pressure isolation valve and then manually tightens it to prevent a small amount of gas from entering the anion bed and mixed bed during operation, which could lead to excessively high oxygen content in the demineralized water.

[0029] This invention achieves fully automatic flow balance in the vacuum degassing tower to produce deoxygenated water by adjusting the clean water pump, intermediate water pump, primary loop makeup water pump, intermediate water pump outlet valve, and vacuum degassing tower liquid level regulating valve, thus meeting the requirements of the vacuum degassing tower for liquid level regulation.

[0030] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications to the technical solutions described in the foregoing embodiments, or equivalent substitutions for some or all of the technical features, do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A control method for a desalinated water system for producing deoxygenated water in a primary start-up stage of a nuclear power plant, the system comprising a clean water pump, the clean water pump and a clean water pump outlet manual valve being connected by a pipeline, the clean water pump outlet manual valve and an activated carbon filter being connected by a pipeline, the activated carbon filter and a cation bed being connected by a pipeline, the cation bed and a vacuum deaerator tower liquid level regulating valve being connected by a pipeline, the vacuum deaerator tower liquid level regulating valve and a vacuum deaerator tower being connected by a pipeline, the vacuum deaerator tower and an intermediate water pump being connected by a pipeline, the intermediate water pump and an intermediate water pump outlet valve being connected by a pipeline, the intermediate water pump outlet valve and an anion bed being connected by a pipeline, the anion bed and a first regeneration air compressor isolation valve being connected, the anion bed and a mixed bed being connected by a pipeline, the mixed bed and a second regeneration air compressor isolation valve being connected, the mixed bed and a primary loop inlet water replenishing valve being connected by a pipeline, the primary loop inlet water replenishing valve and a primary loop water replenishing tank being connected by a pipeline, the primary loop water replenishing tank and a primary loop water replenishing outlet valve being connected by a pipeline, the primary loop water replenishing outlet valve and a primary loop water replenishing pump being connected by a pipeline; a first bypass pipeline is added between the mixed bed and the primary loop inlet valve; a second bypass pipeline is added between the primary loop water replenishing outlet valve and the primary loop water replenishing pump; the first bypass pipeline and the second bypass pipeline are connected through a primary loop water replenishing bypass valve; the first regeneration air compressor isolation valve and the second regeneration air compressor isolation valve are pneumatic diaphragm valves; the first bypass pipeline has a length of 2 meters and an inner diameter of 125 millimeters; the second bypass pipeline has a length of 2 meters and an inner diameter of 125 millimeters; characterized in that the method comprises the following steps: Step 1: before the system produces deoxygenated water, the primary loop inlet valve and the primary loop outlet valve are completely closed, and the primary loop water replenishing bypass valve is opened, so that the produced deoxygenated water directly enters the primary loop water replenishing system without passing through the primary loop water replenishing tank; Step 2: during the system produces deoxygenated water, the first regeneration air compressor isolation valve and the second regeneration air compressor isolation valve are in a manual state, the valves are manually closed, and then the handwheels are manually tightened to ensure that compressed air does not enter the anion bed and the mixed bed; Step 3: during the system produces deoxygenated water, the primary loop water replenishing pump is not started, the intermediate water pump is normally started, the flow rate of the intermediate water pump is 20 to 30 cubic meters per hour, the clean water pump outlet manual valve is adjusted, the vacuum deaerator tower liquid level regulating valve is automatically adjusted within an effective characteristic interval, and the flow rate of the clean water pump is equivalent to the flow rate of the intermediate water pump.

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