A system and method for handling condenser vacuum system level anomalies in a nuclear power plant

Abstract

The present application specifically provides a system and method for processing abnormal liquid level of a nuclear power plant condenser vacuum system, which comprises: a condenser vacuum system exhaust pipeline, which is in a micro-negative pressure condition, can discharge water vapor generated in a steam-water separator to an automatic drain pipeline, and discharge in the form of condensed water; and a negative pressure automatic drain, which is connected to the middle part of the condenser vacuum system exhaust pipeline, and can realize automatic discharge of the condensed water in the condenser vacuum system exhaust pipeline. The method comprises: reducing the overflow port height of the steam-water separator by 30-90 mm, and adding a negative pressure automatic drain to the condenser vacuum system exhaust pipeline. The present application solves the problems of pump automatic shutdown triggered by the condenser vacuum pump steam-water separator liquid level being too high to exceed the pump trip value, and the influence of the condensed water oscillation in the exhaust pipeline on the steam-water separator exhaust port pressure, and reduces the risk of abnormal liquid level of the steam-water separator.

Description

Technical Field

[0001] This invention relates to the field of liquid level control technology for steam-water separators in condenser vacuum systems of nuclear power plants, specifically to a system and method for handling liquid levels in steam-water separators of condenser vacuum systems that deviate from normal values ​​or fluctuate back and forth. Background Technology

[0002] During nuclear power plant operation, the condenser vacuum system needs to operate for extended periods to maintain condenser vacuum levels to ensure safe and reliable unit operation. Taking the M310 unit as an example, during normal operation, the ventilation system network of the nuclear auxiliary building is under slight negative pressure, which causes the liquid level in the steam-water separator of the water ring vacuum pump in the condenser vacuum system to rise by about 60 mm. Under normal system operation, the liquid level in the steam-water separator is around 250 mm. Due to the slight negative pressure in the exhaust network, the liquid level will rise to around 310-320 mm. The system's set pump trip value is 350 mm. Therefore, there have been several instances where abnormalities have caused the liquid level fluctuation in the steam-water separator to exceed the pump trip value, triggering the automatic shutdown of the pump.

[0003] Secondly, the exhaust pipe is a circular pipe with a diameter of 220 mm. Steam inside the pipe condenses slowly and continuously, gradually accumulating a certain amount of condensate at the lowest point of the drain pipe. Because the exhaust pipe is under slight negative pressure, the accumulated water inside the exhaust pipe oscillates back and forth, affecting the pressure of the steam-water separator outlet pipe, which in turn leads to abnormal liquid level in the steam-water separator. Summary of the Invention

[0004] The purpose of this invention is to provide a system and method for handling abnormal liquid levels in the vacuum system of a condenser in a nuclear power plant, which can solve the problems of liquid level deviation from the expected value and liquid level fluctuation in the steam-water separator of the condenser vacuum pump in practical applications.

[0005] The technical solution of the present invention is as follows: A system for handling abnormal liquid levels in the condenser vacuum system of a nuclear power plant, characterized in that the system includes: a condenser vacuum system exhaust pipeline, wherein the condenser vacuum system exhaust pipeline is under a slight negative pressure condition, capable of discharging water vapor generated in the steam-water separator to an automatic drain line for discharge as condensate; and

[0006] The negative pressure automatic drain valve is connected to the middle of the exhaust pipeline of the condenser vacuum system. It can realize the automatic discharge of condensate in the exhaust pipeline of the condenser vacuum system, thereby avoiding the oscillation caused by the accumulation of condensate, which would lead to fluctuations in the liquid level of the steam-water separator.

[0007] Furthermore, the exhaust pipeline of the condenser vacuum system is connected to a negative pressure automatic drain valve.

[0008] Furthermore, the negative pressure automatic steam trap includes a steam trap check valve, a steam trap float, a steam trap valve core, and a steam trap connecting lever.

[0009] Furthermore, the check valve of the steam trap can open when condensate flows through and automatically close when there is no water.

[0010] Furthermore, the steam trap float is fitted onto the steam trap connecting lever and can gradually rise as the liquid level of the negative pressure automatic steam trap rises; the steam trap connecting lever is rotatably connected to a fixed pulley at the bottom of the negative pressure automatic steam trap, and the steam trap valve core is installed in the middle. When the steam trap float rises, it drives the steam trap connecting lever to move, thereby causing the steam trap valve core to lift up and complete the drainage.

[0011] This invention also provides a method for handling abnormal liquid levels in the vacuum system of a condenser in a nuclear power plant, characterized in that the method includes the following steps:

[0012] S1: Adjust the liquid level of the steam-water separator in the condenser vacuum pump: To eliminate the influence of the slight negative pressure in the ventilation system network, reduce the height of the overflow port inside the steam-water separator by 30-90 mm.

[0013] S2: Install a negative pressure automatic drain valve on the exhaust pipeline of the condenser vacuum system.

[0014] Furthermore, the height of the overflow port inside the steam-water separator is adjusted to 60 mm.

[0015] Compared with existing technologies, the advantages of this invention are:

[0016] 1. Through analysis and calculation, the height of the overflow pipeline inside the steam-water separator of the condenser vacuum pump was adjusted to ensure that the liquid level in the steam-water separator is always maintained within the desired range. This solved the problem of the pump automatically shutting down when the separator liquid level exceeded the trip value in some existing units.

[0017] 2. By adding a continuous automatic drainage device at the lowest point of the exhaust pipeline, the accumulated water in the exhaust pipeline can be automatically discharged, avoiding the problem of condensate accumulating to a certain amount during long-term operation, causing oscillations that affect the exhaust port pressure of the steam-water separator, and thus leading to abnormal liquid level in the steam-water separator. Attached Figure Description

[0018] Figure 1 is a simplified flowchart of the normal operation of a condenser vacuum system provided by the present invention.

[0019] Figure 2 is a schematic diagram of a negative pressure automatic drain valve provided by the present invention;

[0020] In the diagram: 1. Overflow line of steam-water separator; 2. Level gauge of steam-water separator; 3. Low-point drain line of exhaust line; 4. Steam-water separator of condenser vacuum pump; 101. Overflow port of overflow line inside steam-water separator; 201. Magnetic float level gauge; 202. Isolation valve at the bottom of level gauge; 301. Negative pressure automatic drain valve; 3011. Check valve of drain valve; 3012. Float ball of drain valve; 3013. Drain valve core; 3014. Connecting lever of drain valve. Detailed Implementation

[0021] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] like Figure 1-2 As shown, a system for handling abnormal liquid levels in the condenser vacuum system of a nuclear power plant includes a condenser vacuum system exhaust pipeline 5. The condenser vacuum system exhaust pipeline 5 is under a slight negative pressure condition, which can discharge water vapor generated in the steam-water separator 4 to an automatic drain pipeline and discharge it in the form of condensate. A negative pressure automatic drain 301 is connected to the middle of the condenser vacuum system exhaust pipeline 5, which can realize the automatic discharge of condensate in the condenser vacuum system exhaust pipeline 5, thereby avoiding the accumulation of condensate and the resulting oscillation, which would cause fluctuations in the liquid level of the steam-water separator 4.

[0023] This invention also provides a method for handling abnormal liquid levels in the vacuum system of a condenser in a nuclear power plant, the method comprising the following steps:

[0024] S1: Adjust the liquid level of the condenser vacuum pump steam-water separator 4: In order to eliminate the influence of the slight negative pressure state of the ventilation system pipeline, lower the height of the overflow port 101 inside the steam-water separator by 30-60 mm.

[0025] S2: Install a negative pressure automatic drain valve 301 on the exhaust pipeline 5 of the condenser vacuum system.

[0026] Specifically, the lowering height of the overflow port 101 inside the steam-water separator is adjusted to 60 mm.

[0027] The implementation principle of a system for handling abnormal liquid levels in the vacuum system of a nuclear power plant condenser in this embodiment is as follows: The negative pressure automatic steam trap 301 includes a steam trap check valve 3011, a steam trap float 3012, a steam trap valve core 3013, and a steam trap connecting lever 3014. The steam trap check valve 3011 can open when condensate flows through and automatically close when there is no water; the steam trap float 3012 is sleeved on the steam trap connecting lever 3014 and can gradually rise as the liquid level of the negative pressure automatic steam trap 301 rises; the steam trap connecting lever 3014 is rotatably connected to a fixed pulley at the bottom of the negative pressure automatic steam trap 301, and the steam trap valve core 3013 is installed in the middle. When the steam trap float 3012 rises, it drives the steam trap connecting lever 3014 to move, thereby causing the steam trap valve core 3013 to rise and complete the drainage.

[0028] In the description of this invention, it should be noted that the terms "left end", "right end", "above", "below", "outer side", "inner side", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0029] Furthermore, the terms “first,” “second,” and “third” are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0030] The above-described embodiments are merely one implementation of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A system for handling abnormal liquid levels in the vacuum system of a nuclear power plant condenser, characterized in that, The system includes: The condenser vacuum system exhaust line (5) is under a slight negative pressure inside, which can discharge the water vapor generated in the steam-water separator (4) to the automatic drain line and discharge it in the form of condensate. The negative pressure automatic drain valve (301) is connected to the middle of the exhaust pipeline (5) of the condenser vacuum system. It can realize the automatic discharge of condensate in the exhaust pipeline (5) of the condenser vacuum system, thereby avoiding the oscillation caused by the accumulation of condensate, which leads to the fluctuation of the liquid level of the steam-water separator (4). The negative pressure automatic steam trap (301) includes a steam trap check valve (3011), a steam trap float (3012), a steam trap valve core (3013), and a steam trap connecting lever (3014).

2. The system for handling abnormal liquid levels in the vacuum system of a nuclear power plant condenser according to claim 1, characterized in that: The check valve (3011) of the steam trap is able to open when condensate flows through and automatically close when there is no water.

3. The system for handling abnormal liquid levels in the vacuum system of a nuclear power plant condenser according to claim 1, characterized in that: The steam trap float (3012) is sleeved on the steam trap connecting lever (3014) and can gradually rise as the liquid level of the negative pressure automatic steam trap (301) rises. The steam trap connecting lever (3014) is rotatably connected to the fixed pulley at the bottom of the negative pressure automatic steam trap (301), and the steam trap valve core (3013) is installed in the middle. When the steam trap float (3012) rises, it drives the steam trap connecting lever (3014) to move, thereby causing the steam trap valve core (3013) to lift up and complete the drainage.

4. The system for handling abnormal liquid levels in the vacuum system of a nuclear power plant condenser according to claim 1, characterized in that: Adjust the height of the overflow port (101) inside the steam-water separator to decrease by 60 mm.

5. A method for handling abnormal liquid levels in the vacuum system of a condenser in a nuclear power plant, characterized in that, Using the system as described in claim 1, the method includes the following steps: S1: Adjust the liquid level of the condenser vacuum pump steam-water separator (4): In order to eliminate the influence of the slight negative pressure state of the ventilation system pipeline, reduce the height of the overflow port (101) inside the steam-water separator by 30-90 mm. S2: Install a negative pressure automatic drain valve (301) on the exhaust pipeline (5) of the condenser vacuum system.

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