Cooling water supply method and device for primary-loop small-flow charging pump

Abstract

The invention relates to the field of nuclear power operation control, in particular to a primary-loop small-flow charging pump cooling water supply method and device. The supply method comprises the following steps: during the standby period of the primary-loop small-flow uprush pump, cooling of a plunger of the charging pump is realized by a middle-loop cooling water system in a closed circulating cooling manner; during operation of the charging pump, plunger cooling of the charging pump is supplied by the demineralized water supply system in an open circulating manner; whether inner leakage exists in a water supplementing valve of a water storage tank of the intermediate loop cooling water system or not during the operation period of the charging pump is judged, if inner leakage exists, the intermediate loop cooling water system is switched to, cooling water is provided by the intermediate loop cooling water system, and open type circulation is kept; and if the inner leakage does not exist, the original desalted water supply system is kept to supply in an open circulating manner. Boron-containing and radioactive media in the primary loop are prevented from entering a cooling water system, and the current demineralized water loss amount and the radioactive waste liquid discharge amount are reduced.

Description

Technical Field

[0001] The invention relates to the field of nuclear power operation control, and in particular to a method and a device for supplying cooling water for a small-flow charging pump in a primary circuit. Background Art

[0002] The small-flow charging pump in a single circuit was originally designed with only a closed cooling method for the intermediate cooling water circuit. Its operation mode was relatively simple and some problems had occurred during its long-term operation.

[0003] Firstly, the medium flowing in the plunger of the primary-circuit small-flow charging pump is the high-pressure medium of the primary circuit. After long-term operation, due to the poor sealing of the plunger, the medium of the primary circuit repeatedly enters the intermediate cooling water circuit, resulting in increased radioactivity of the intermediate cooling water circuit.

[0004] Furthermore, the intermediate loop cooling water system water replenishment electric valve has serious internal leakage. The valve is located in the water supply manifold and cannot be isolated for maintenance during daily periods. As a result, the intermediate loop cooling water system head water tank is actually in a state of continuous water replenishment and overflow. According to the statistics of wastewater discharge, the monthly water replacement volume reaches 100-200m 3 At the same time, the corrosion inhibitor concentration in the intermediate cooling water system continues to decrease due to the continuous loss of the added corrosion inhibitor with the water change, resulting in the corrosion inhibitor concentration not meeting the chemical supervision outline and copper ion exceeding the standard. In summary, this not only leads to a large amount of medium loss in the intermediate cooling loop system, but also causes the system corrosion inhibitor concentration to deviate, and in severe cases, the system corrosion may be aggravated. Summary of the invention

[0005] The technical problem to be solved by the present invention is: to provide a cooling water supply method for a small-flow charging pump in a primary circuit, which is used to prevent boron-containing and radioactive media in the primary circuit from entering the cooling water system on the one hand, and can quickly and effectively solve the problem of short-term non-isolation and maintenance of valve internal leakage in the intermediate cooling water system on the other hand, while reducing the current loss of desalted water and the discharge of radioactive waste liquid, increasing the monthly water replacement volume of the system, and preventing the corrosion problem caused by excessive copper ions in the intermediate cooling water system when the corrosion inhibitor concentration is low.

[0006] The present invention provides a method for supplying cooling water to a charging pump with a small flow rate in a single circuit, comprising the following steps:

[0007] Step 1: During the standby period of the primary circuit low-flow charging pump, the plunger cooling of the primary circuit low-flow charging pump is achieved by the intermediate circuit cooling water system through a closed-loop cooling method;

[0008] Step 2: During the operation of the primary circuit low-flow charging pump, the plunger cooling of the primary circuit low-flow charging pump is supplied by the demineralized water supply system through an open cycle;

[0009] Step 3: Determine whether there is internal leakage in the water supply valve of the water storage tank of the intermediate loop cooling water system during the operation of the small flow charging pump of the primary loop. If there is internal leakage, switch to the intermediate loop cooling water system, which provides cooling water and maintains an open circulation;

[0010] If there is no internal leakage, maintain the original demineralized water supply system through open circulation.

[0011] Preferably, the closed-loop cooling method is that the cooling water comes from the intermediate loop cooling water system, cools the small-flow charging pump of a circuit, and then returns to the intermediate loop cooling water system.

[0012] Preferably, the desalted water supply system is provided through an open circulation system as follows:

[0013] The desalted water supply system provides cooling water to the plunger of the small-flow charging pump in a circuit. The cooling water cools the plunger and then is discharged into a pit for collection and no longer returns to the original desalted water supply system.

[0014] Preferably, in step three, if there is internal leakage, the system will be switched to the intermediate loop cooling water system, which will provide cooling water, and the cooling water will cool the plunger and then be discharged into the pit for collection.

[0015] Preferably, in the step 3, before switching the intermediate loop cooling water system, the step further includes:

[0016] Take samples from the intermediate loop cooling water system, detect and analyze the ion concentration,

[0017] When the phosphate radical is less than 0.1 mg / L and the concentration of the metal rust inhibitor and / or corrosion inhibitor is less than 0.5 mg / L, switch to the intermediate loop cooling water system.

[0018] Preferably, in step three, the copper ion concentration is monitored regularly. If the copper ion concentration in the intermediate loop cooling water system rises to 250 μg / L, the resin bed is flushed and put into operation to control the copper ions by purification to maintain the water quality of the intermediate loop cooling water system.

[0019] Preferably, in step three,

[0020] After switching to the intermediate loop cooling water system, the internal leakage of the water supply valve Q1 is calculated based on the rise in the liquid level of the intermediate cooling water loop header tank, and compared with the required cooling water volume Q2 for the plunger cooling water:

[0021] (1) If Q1 < Q2, pay attention to the water replenishment at any time. If the water replenishment is abnormal, transfer the cooling water of the small pump back to the desalted water supply system in time;

[0022] (2) If Q1 ≥ Q2, pay attention to the overflow of the header box of the intermediate cooling water circuit and the drainage direction; if the difference is not large, adjust the cooling water volume Q2 required for the plunger cooling water so that Q1 = Q2.

[0023] The present invention also provides a cooling water supply device for a small-flow charging pump in a primary circuit, wherein one side of the water inlet of the small-flow charging pump in the primary circuit is connected to the cooling water supply pipeline of the intermediate circuit, and one side of the water outlet of the small-flow charging pump in the primary circuit is connected to the cooling water discharge pipeline of the intermediate circuit, and further comprises:

[0024] A desalted water supply pipeline is added on the water inlet side of the charging pump with a small flow rate in a circuit, and a desalted water drain outlet pipeline is added on the water outlet side.

[0025] Preferably, a third valve is provided on the desalted water supply pipeline, and a fourth valve is provided on the desalted water drainage pipeline;

[0026] A first valve is arranged on the intermediate loop cooling water supply pipeline, and a second valve is arranged on the intermediate loop cooling water discharge pipeline.

[0027] Preferably, the desalted water outlet pipeline leads to the pit to maintain an open cooling mode.

[0028] Compared with the prior art, the cooling water supply method of the primary circuit small flow charging pump of the present invention has the following beneficial effects:

[0029] (1) The conversion of multiple supply modes of the plunger cooling water of a small-flow charging pump in a circuit is realized, which increases the diversity of operation modes, improves the operation reliability of the small-flow charging pump, and avoids the risk of the small-flow charging pump being unavailable under the condition of a single cooling water source failure.

[0030] (2) The problem of increased radioactivity in the intermediate cooling water source has been solved. Since the primary charging pump was switched to open cooling, the intermediate circuit cooling water system has been operating well. There has been no problem of increased radioactivity levels due to the low-flow charging pump. The charging pump plunger is in good cooling condition and is operating stably.

[0031] (3) During the isolation and standby period of the small pump, the intermediate cooling water circuit is promptly switched to a closed circulation, which can save no less than 150L / h of water per hour.

[0032] (4) The serious internal leakage problem of the water supply electric valve in the intermediate loop cooling water system has been solved. The overflow water source can be used to cool the small flow rate charging pump of the first loop, which can significantly reduce the current loss of desalted water while ensuring the operation of the charging pump.

[0033] (5) It saves desalted water and significantly reduces the current loss of desalted water and the discharge of radioactive waste liquid. According to the statistics of wastewater discharge, in the special case of internal leakage of the water supply valve of the water storage tank of the intermediate loop cooling water system, the monthly water replacement volume reaches 100-200m 3 This matches the required flow rate of cooling water for the plunger of a small-flow charging pump in a single circuit. Using this part of water for cooling the plunger of a small pump not only saves water resources, but also ensures the operation effect of the charging pump. This measure has achieved the results of reducing costs and increasing efficiency.

[0034] (6) Solved the problem of excessive copper ions. For the intermediate loop cooling water system, continuous dynamic water exchange reduces the copper ion content in the system, improves water quality, and avoids the risk of corrosion caused by the continuous loss of added corrosion inhibitors with water exchange, resulting in a continuous decrease in the concentration of corrosion inhibitors in the intermediate loop cooling water system, as well as the problem of corrosion inhibitor concentration not meeting the chemical supervision outline and excessive copper ions.

[0035] This method has been used in the Jiangsu Nuclear Power Phase II Project, achieving the goal of energy saving, cost reduction and efficiency improvement. At the same time, this conversion method uses the existing systems and instrumentation pipelines of the unit, and does not require new equipment or devices. Using this method to solve unit problems is more economical and efficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 A schematic diagram showing a cooling circuit for the plunger of a small-flow charging pump in a circuit;

[0037] In the figure,

[0038] 1-first circuit Xiao Li Luliang charging pump, 2-intermediate circuit cooling water supply pipeline, 3-intermediate circuit cooling water discharge pipeline, 4-desalting water supply pipeline, 5-desalting water drain outlet pipeline, 6-first valve, 7-second valve, 8-third valve, 9-fourth valve. DETAILED DESCRIPTION

[0039] In order to further understand the present invention, the embodiments of the present invention are described below in conjunction with examples, but it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the present invention.

[0040] The present invention adds an open cooling pipeline to the desalted water supply system and selects different cooling water supply loops under different working conditions.

[0041] An embodiment of the present invention discloses a method for supplying cooling water to a charging pump with a small flow rate in a single circuit, comprising the following steps:

[0042] Step 1: During the standby period of the primary circuit low-flow charging pump, the plunger cooling of the primary circuit low-flow charging pump is achieved by the intermediate circuit cooling water system through a closed-loop cooling method;

[0043] The closed-loop cooling method is that the cooling water comes from the intermediate loop cooling water system, cools the small-flow charging pump of a loop, and then returns to the intermediate loop cooling water system.

[0044] Step 2: During the operation of the primary circuit low-flow charging pump, the plunger cooling of the primary circuit low-flow charging pump is supplied by the demineralized water supply system through an open cycle;

[0045] The desalted water supply system is specifically provided through an open circulation:

[0046] The desalted water supply system provides cooling water to the plunger of the small-flow charging pump in a circuit. The cooling water cools the plunger and then is discharged into a pit for collection and no longer returns to the original desalted water supply system.

[0047] Step 3: Determine whether there is an internal leakage in the water supply valve of the water storage tank of the intermediate loop cooling water system during the operation of the small flow charging pump of the primary loop. The internal leakage of the water supply valve causes the water storage tank of the intermediate loop cooling water system to continuously replenish and overflow, thereby realizing the water change of the intermediate loop cooling water system. Through the water change, the reagent content and copper ion content in the intermediate loop cooling water system are constantly changing;

[0048] After detection, if there is internal leakage, it will be switched to the intermediate loop cooling water system, which will provide cooling water and maintain an open circulation;

[0049] Specifically, the intermediate loop cooling water system is switched to provide cooling water, which cools the plunger and is then discharged into a pit for collection.

[0050] Switching the cooling water system can make use of the water originally lost by overflow of the water storage tank of the intermediate loop cooling water system to cool the small flow charging pump of the first loop. This can significantly reduce the current loss of desalted water and the discharge of radioactive wastewater, while increasing the monthly water change volume of the intermediate loop cooling water system, and preventing corrosion problems caused by excessive copper ions in the intermediate loop cooling water system when the corrosion inhibitor concentration is low.

[0051] Before switching the intermediate loop cooling water system, it also includes:

[0052] Take samples from the intermediate loop cooling water system, detect and analyze the ion concentration,

[0053] Due to the continuous internal leakage and overflow of the water supply valve, the content of reagents and copper ions in the water storage tank of the intermediate loop cooling water system is reduced, and the liquid level of the water storage tank of the intermediate loop cooling water system is kept rising slowly.

[0054] When the phosphate radical is less than 0.1 mg / L and the concentration of the metal rust inhibitor and / or corrosion inhibitor is less than 0.5 mg / L, switch to the intermediate loop cooling water system.

[0055] Alternatively, tolyltriazole is used as a metal rust inhibitor and corrosion inhibitor.

[0056] According to the water quality, the copper ion concentration is monitored regularly. If the copper ion concentration in the intermediate loop cooling water system rises to 250μg / L, the resin bed is flushed and put into operation to control the copper ions through purification to maintain the water quality of the intermediate loop cooling water system.

[0057] After switching to the intermediate loop cooling water system, the internal leakage of the water supply valve Q1 is calculated based on the rise in the liquid level of the intermediate cooling water loop header tank, and compared with the required cooling water volume Q2 for the plunger cooling water:

[0058] (1) If Q1 < Q2, pay attention to the water replenishment at any time. If the water replenishment is abnormal, transfer the cooling water of the small pump back to the desalted water supply system in time;

[0059] (2) If Q1 ≥ Q2, pay attention to the overflow of the header box of the intermediate cooling water circuit and the drainage direction; if the difference is not large, adjust the cooling water volume Q2 required for the plunger cooling water so that Q1 = Q2.

[0060] By adjusting to meet Q1=Q2, the optimal dynamic balance of supply and demand of cooling water is achieved, achieving the best energy-saving and emission reduction effects.

[0061] After switching to the intermediate loop cooling water system, the rate of drop in the liquid level in the intermediate loop cooling water system tank will increase, and continuous attention needs to be paid to the water replenishment situation.

[0062] If there is no internal leakage, maintain the original demineralized water supply system through open circulation.

[0063] The embodiment of the present invention also discloses a circuit small flow charging pump cooling water supply device, such as Figure 1 As shown, the water inlet side of the primary circuit small flow charging pump 1 is connected to the intermediate circuit cooling water supply pipeline 2, and the water outlet side thereof is connected to the intermediate circuit cooling water discharge pipeline 3, and further includes:

[0064] A desalted water supply pipeline 4 is added to the water inlet side of the charging pump with a small flow rate in a circuit, and a desalted water outlet pipeline 5 is added to the water outlet side thereof.

[0065] A first valve 6 is provided on the intermediate loop cooling water supply pipeline 2, and a second valve 7 is provided on the intermediate loop cooling water discharge pipeline 3;

[0066] The desalted water supply pipeline 4 is provided with a third valve 8, and the desalted water drainage pipeline 5 is provided with a fourth valve 9;

[0067] The desalted water outlet pipeline is led into the pit to maintain an open cooling mode.

[0068] The first valve 6, the second valve 7, the third valve 8 and the fourth valve 9 may be manual isolation valves.

[0069] During the standby period of the small flow charging pump of the primary circuit, the closed circulation cooling mode of the intermediate circuit cooling water system is maintained. At this time, the first valve 6 and the second valve 7 are opened, and the third valve 8 and the fourth valve 9 are closed.

[0070] During the operation of the primary circuit low-flow charging pump, the conversion plunger cooling water is provided by the demineralized water supply system, and an open cooling method is adopted. At this time, the first valve 6 and the second valve 7 are closed, and the third valve 8 and the fourth valve 9 are opened.

[0071] When the water supply valve of the intermediate loop cooling water system leaks, or the system needs to change water to reduce the copper ion concentration, the plunger cooling water supply is changed to the intermediate loop cooling water system, and the cooling mode is opened. At this time: the first valve 6 is opened; the second valve 7 and the third valve 8 are closed; the fourth valve 9 maintains a certain opening according to the cooling water volume requirements. The cooling water overflowing from the intermediate loop cooling water system water tank is cooled by cooling the plunger and then discharged to the room pit.

[0072] The above embodiments are only used to help understand the method and core idea of ​​the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0073] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for supplying cooling water to a small-flow charging pump in a primary circuit, characterized in that: The following steps are involved: Step 1: During the standby period of the primary circuit low-flow charging pump, the plunger cooling of the primary circuit low-flow charging pump is achieved by the intermediate circuit cooling water system through a closed-loop cooling method; Step 2: During the operation of the primary circuit low-flow charging pump, the plunger cooling of the primary circuit low-flow charging pump is supplied by the demineralized water supply system through an open cycle; Step 3: Determine whether there is internal leakage in the water supply valve of the water storage tank of the intermediate loop cooling water system during the operation of the small flow charging pump of the primary loop. If there is internal leakage, switch to the intermediate loop cooling water system, which provides cooling water and maintains an open circulation; If there is no internal leakage, maintain the original demineralized water supply system through open circulation.

2. The method for supplying cooling water for a small-flow charging pump in a primary circuit according to claim 1 is characterized in that: The closed-loop cooling method is that the cooling water comes from the intermediate loop cooling water system, cools the small-flow charging pump of a loop, and then returns to the intermediate loop cooling water system.

3. The method for supplying cooling water to a primary circuit charging pump with a small flow rate according to claim 1 is characterized in that: The desalted water supply system is specifically provided through an open circulation: The desalted water supply system provides cooling water to the plunger of the small-flow charging pump in a circuit. The cooling water cools the plunger and then is discharged into a pit for collection and no longer returns to the original desalted water supply system.

4. The method for supplying cooling water to a primary circuit charging pump with a small flow rate according to claim 1, characterized in that: In the step three, if there is internal leakage, the system will be switched to the intermediate loop cooling water system, which will provide cooling water. The cooling water will cool the plunger and then be discharged into the pit for collection.

5. The method for supplying cooling water to a primary circuit charging pump with a small flow rate according to claim 1, characterized in that: In the step 3, before switching the intermediate loop cooling water system, the step further includes: Take samples from the intermediate loop cooling water system, detect and analyze the ion concentration, When the phosphate radical is less than 0.1 mg / L and the concentration of the metal rust inhibitor and / or corrosion inhibitor is less than 0.5 mg / L, switch to the intermediate loop cooling water system.

6. The method for supplying cooling water to a primary circuit charging pump with a small flow rate according to claim 5, characterized in that: In the step three, the copper ion concentration is monitored regularly. If the copper ion content of the intermediate loop cooling water system rises to 250 μg / L, the resin bed is flushed and put into operation to control the copper ions through purification to maintain the water quality of the intermediate loop cooling water system.

7. The method for supplying cooling water for a small-flow charging pump in a primary circuit according to claim 1, characterized in that: In the step three, After switching to the intermediate loop cooling water system, the internal leakage of the water supply valve Q1 is calculated based on the rise in the liquid level of the intermediate cooling water loop header tank, and compared with the required cooling water volume Q2 for the plunger cooling water: (1) If Q1 < Q2, pay attention to the water replenishment at any time. If the water replenishment is abnormal, transfer the cooling water of the small pump back to the desalted water supply system in time; (2) If Q1 ≥ Q2, pay attention to the overflow of the header box of the intermediate cooling water circuit and the drainage direction; if the difference is not large, adjust the cooling water volume Q2 required for the plunger cooling water so that Q1 = Q2.

8. A cooling water supply device for a small-flow charging pump in a primary circuit, wherein the water inlet side of the small-flow charging pump in a primary circuit is connected to the cooling water supply pipeline of the intermediate circuit, and the water outlet side thereof is connected to the cooling water discharge pipeline of the intermediate circuit, characterized in that: Also includes: A desalted water supply pipeline is added on the water inlet side of the charging pump with a small flow rate in a circuit, and a desalted water drain outlet pipeline is added on the water outlet side.

9. The cooling water supply device for a small-flow charging pump in a primary circuit according to claim 8, characterized in that: The desalted water supply pipeline is provided with a third valve, and the desalted water drainage pipeline is provided with a fourth valve; A first valve is arranged on the intermediate loop cooling water supply pipeline, and a second valve is arranged on the intermediate loop cooling water discharge pipeline.

10. The cooling water supply device for a primary circuit with a small flow rate charging pump according to claim 8, characterized in that: The desalted water outlet pipeline is led into the pit to maintain an open cooling mode.

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