A two-circuit cooling system

Abstract

The present invention provides a two-circuit cooling system, which comprises: a first pipeline, wherein the first end of the first pipeline is a steam inlet; a second pipeline, wherein the first end of the second pipeline is connected to the first connecting port of the first pipeline, and the second pipeline is provided with a first isolation valve and a flow limiting orifice plate in sequence along the direction from the first end to the second end of the second pipeline; a third pipeline, wherein the first end of the third pipeline is connected to the second connecting port of the first pipeline, and the second end of the third pipeline is connected to the second end of the second pipeline at a first position, and the third pipeline is provided with a second isolation valve and a first regulating valve in sequence along the direction from the first end to the second end of the third pipeline, and the pipe diameter of the third pipeline is larger than that of the second pipeline; and a fourth pipeline, wherein the first end of the fourth pipeline is connected to the first position, the second end of the fourth pipeline is a discharge port, and the first position is a position between the flow limiting orifice plate and the first regulating valve. The present invention improves the reliability of the two-circuit cooling system in responding to accidents.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of nuclear power, and in particular to a secondary circuit cooling system. Background Art

[0002] The new energy industry is developing rapidly, and nuclear power is one of them. The secondary cooling system is an important auxiliary system of nuclear power plants. Generally speaking, when a small or medium-sized rupture occurs in the primary cooling system or the heat transfer tube of the steam generator breaks, the secondary cooling system is required to cool down the primary cooling system. However, the existing secondary cooling system uses automatic adjustment of a fixed cooling rate, which requires a complex control system for adjustment, and the adjustment accuracy is poor at low flow rates. Therefore, the existing secondary cooling system has poor reliability in dealing with accidents. Summary of the invention

[0003] The purpose of the embodiment of the present invention is to provide a two-circuit cooling system, which solves the problem of poor reliability of the current two-circuit cooling system.

[0004] In order to achieve the above object, an embodiment of the present invention provides a secondary cooling system, which is applied to a nuclear island. The secondary cooling system includes:

[0005] a first pipeline, wherein a first end of the first pipeline is a steam inlet;

[0006] a second pipeline, wherein a first end of the second pipeline is connected to a first communication port of the first pipeline, and a first isolation valve and a flow limiting orifice are sequentially arranged in the second pipeline along a direction from the first end to the second end of the second pipeline;

[0007] a third pipeline, wherein a first end of the third pipeline is connected to a second communication port of the first pipeline, a second end of the third pipeline is connected to a second end of the second pipeline at a first position, a second isolation valve and a first regulating valve are sequentially arranged in the third pipeline along a direction from the first end to the second end of the third pipeline, and a diameter of the third pipeline is larger than a diameter of the second pipeline;

[0008] A fourth pipeline, wherein a first end of the fourth pipeline is connected to the first position, a second end of the fourth pipeline is a drain port, and the first position is a position between the flow limiting orifice plate and the first regulating valve.

[0009] Optionally, both the first isolation valve and the second isolation valve are electric isolation valves, and the first regulating valve is an electric regulating valve.

[0010] Optionally, the second end of the fourth pipeline is connected to a muffler.

[0011] Optionally, the first isolation valve, the second isolation valve and the first regulating valve are all electrically connected to a backup power supply.

[0012] One of the above technical solutions has the following advantages or beneficial effects:

[0013] A two-circuit cooling system provided by an embodiment of the present invention comprises: a first pipeline, wherein the first end of the first pipeline is a steam inlet; a second pipeline, wherein the first end of the second pipeline is connected to the first connecting port of the first pipeline, and the second pipeline is provided with a first isolation valve and a flow limiting orifice plate in sequence along the direction from the first end to the second end of the second pipeline; a third pipeline, wherein the first end of the third pipeline is connected to the second connecting port of the first pipeline, and the second end of the third pipeline is connected to the second end of the second pipeline at a first position, and the third pipeline is provided with a second isolation valve and a first regulating valve in sequence along the direction from the first end to the second end of the third pipeline, and the pipe diameter of the third pipeline is larger than that of the second pipeline; a fourth pipeline, wherein the first end of the fourth pipeline is connected to the first position, and the second end of the fourth pipeline is a discharge port, and the first position is a position between the flow limiting orifice plate and the first regulating valve. In this way, the first isolation valve is triggered to open by an accident signal, and is automatically closed after the pressure of the second pipeline drops to a set set value. In the later stage of the accident, the first-circuit cooling system is cooled by manually opening the second isolation valve and manually adjusting the first regulating valve. The second pipeline adopts a switch mode and the third pipeline adopts a manual adjustment mode to deal with accidents, which is more reliable than using a complex adjustment mode through the second pipeline and the third pipeline to deal with accidents. The reliability of the secondary circuit cooling system in dealing with accidents is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 A schematic diagram of the structure of a two-circuit cooling system provided by an embodiment of the present invention;

[0015] Figure 2 A schematic structural diagram of another two-circuit cooling system provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0016] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0017] like Figure 1 As shown, an embodiment of the present invention provides a secondary cooling system, which is applied to a nuclear island. The secondary cooling system includes:

[0018] A first pipeline 1, wherein a first end of the first pipeline 1 is a steam inlet;

[0019] A second pipeline 2, wherein a first end of the second pipeline 2 is connected to a first connecting port of the first pipeline 1, and a first isolation valve 20 and a flow limiting orifice 21 are sequentially arranged in the second pipeline 2 along a direction from the first end to the second end of the second pipeline 2;

[0020] a third pipeline 3, wherein a first end of the third pipeline 3 is connected to a second connecting port of the first pipeline 1, a second end of the third pipeline 3 is connected to a second end of the second pipeline 2 at a first position, a second isolation valve 30 and a first regulating valve 31 are sequentially provided in the third pipeline 3 along a direction from the first end to the second end of the third pipeline 3, and a diameter of the third pipeline 3 is larger than a diameter of the second pipeline 2;

[0021] A fourth pipeline 4 , a first end of the fourth pipeline 4 is connected to the first position, a second end of the fourth pipeline 4 is a discharge port, and the first position is a position between the flow limiting orifice 21 and the first regulating valve 31 .

[0022] Among them, the aperture of the flow limiting orifice 21 is determined during the design period. According to the steam flow after the accident (for example: a small or medium-sized rupture in the primary cooling system or a rupture of the steam generator heat transfer tube), the parameters of the first isolation valve 20 and the pipeline characteristics of the second pipeline 20, the aperture of the flow limiting orifice 21 is preliminarily calculated, and the flow limiting orifice 21 is selected. During the unit commissioning, the aperture of the flow limiting orifice 21 is accurately calibrated according to the field test.

[0023] The first connecting port and the second connecting port are at different positions on the first pipeline 1 .

[0024] The first isolation valve 20 is closed during the process of cooling and reducing pressure until the set pressure setting value is reached, and no adjustment is performed during this period.

[0025] The diameter of the third pipeline 3 may be 10 times that of the second pipeline 2 .

[0026] Among them, the first isolation valve 20 can be automatically controlled by the secondary circuit cooling system, and the second isolation valve 30 and the first regulating valve 31 are manually controlled by the staff. Manual adjustment of the first regulating valve 31 facilitates precise control of the cooling rate of the primary circuit cooling system at a small opening.

[0027] Among them, the first isolation valve 20 and the second isolation valve 30 are in a closed state when no accident occurs (for example, there is a small or medium-sized rupture in the primary circuit cooling system or the heat transfer tube of the steam generator is broken). The first isolation valve 20 works in the short-term cooling stage when the accident signal is triggered, and the second isolation valve 30 works in the long-term cooling stage after the accident occurs.

[0028] The flow limiting orifice 21 allows steam to pass in a direction from the first end of the second pipeline 2 to the second end of the second pipeline 2 .

[0029] In addition, the second pipeline 2 and the third pipeline 3 in the secondary cooling system cool down and reduce the pressure of the high-temperature steam in the first pipeline 1, which can indirectly cool down and reduce the pressure of the primary cooling system.

[0030] It should be noted that when a small or medium-sized rupture occurs in the primary cooling system or the heat transfer pipe of the steam generator breaks, after the first isolation valve 20 is opened, the medium in the second pipeline 2 is in a critical flow state, and the pipe diameter of the second pipeline 2 needs to be simulated and analyzed according to the heat storage, decay heat and cooling rate requirements of the primary cooling system. If the pipe diameter is large, the cooling rate of the primary cooling system will be large, exceeding the bearing limit of the pipeline or pressure vessel of the primary cooling system, affecting the service life, and even causing rupture. If the pipe diameter is small, the cooling rate of the primary cooling system will be small, affecting the accident response process, and more serious accidents may occur. After the second pipeline 2 adopts the switch mode, the cooling rate of the primary cooling system will be a variable value. It is necessary to analyze the change of the cooling rate of the primary cooling system under different second pipeline 2 diameters, so as to achieve a state that does not affect the accident process and the equipment of the primary cooling system can withstand it, which more effectively improves the reliability of the secondary cooling system. The pressure of the second pipeline 2 is the same as the pressure of the secondary cooling system.

[0031] In this embodiment, if there is a small or medium-sized rupture in the primary cooling system or the heat transfer tube of the steam generator is broken, after the secondary cooling system receives the accident signal, the pressure setting value of the first isolation valve 20 is first set to be lower than the pressure of the secondary cooling system corresponding to the injection of the safety injection pump of the primary cooling system (for example: the injection pressure of the safety injection pump is 8.85Mpa.a, and the corresponding pressure of the secondary cooling system is about 6Mpa.a. After receiving the accident signal, the pressure setting value of the first isolation valve 20 is set to 5.25Mpa.a). Secondly, the secondary cooling system automatically opens the first isolation valve 20, and the medium in the second pipeline 2 is in a critical flow state, which can reduce the temperature and pressure of the primary cooling system, and automatically closes after the pressure of the secondary cooling system drops to the set setting value (for example: 5.25Mpa.a). In the later stage of the accident, the staff manually opens the second isolation valve 30 through the console and indirectly controls the cooling rate of the primary cooling system by manually setting the opening of the first regulating valve 31. In this way, the accident response method of the second pipeline 2 using a switch and the third pipeline 3 using a manual adjustment method improves the reliability of the secondary circuit cooling system in responding to accidents.

[0032] Optional, see Figure 2 The first isolation valve 20 and the second isolation valve 30 are both electric isolation valves, and the first regulating valve 31 is an electric regulating valve.

[0033] It should be noted that the first isolation valve 20 and the second isolation valve 30 may also be solenoid valve driven isolation valves, pneumatic isolation valves or gas-liquid linkage isolation valves. The first regulating valve 31 may also be a solenoid valve driven regulating valve, pneumatic regulating valve or gas-liquid linkage regulating valve.

[0034] In this embodiment, the first isolation valve 20, the second isolation valve 30 and the first regulating valve can all be electrically controlled, which is convenient for the staff to operate and improves the safety of the secondary circuit cooling system.

[0035] Optional, see Figure 2 The second end of the fourth pipeline 4 is connected to the muffler 40.

[0036] In this embodiment, when the secondary cooling system is in operation, the steam whose pressure is reduced through the second pipeline 2 and the third pipeline 3 is discharged from the fourth pipeline 4. A muffler 40 is provided at the discharge port to reduce system noise and improve the reliability of the secondary cooling system.

[0037] Optional, see Figure 2 The first isolation valve 20, the second isolation valve 30 and the first regulating valve 31 are all electrically connected to a backup power supply.

[0038] The backup power source may include at least one of a generator and a mobile power source, wherein the generator may be a diesel generator and the mobile power source may be a battery.

[0039] It should be noted that when the first isolation valve 20, the second isolation valve 30 and the first regulating valve 31 are pneumatically driven, the backup power supply can be understood as a backup air compression tank.

[0040] In this embodiment, the secondary circuit cooling system further includes a backup power supply, and the power supplies of the first isolation valve 20, the second isolation valve 30 and the first regulating valve 31 are all electrically connected to the backup power supply, thereby further improving the reliability of the secondary circuit cooling system.

[0041] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A two-circuit cooling system, characterized in that: include: a first pipeline, wherein a first end of the first pipeline is a steam inlet; a second pipeline, wherein a first end of the second pipeline is connected to a first communication port of the first pipeline, and a first isolation valve and a flow limiting orifice are sequentially arranged in the second pipeline along a direction from the first end to the second end of the second pipeline; a third pipeline, wherein a first end of the third pipeline is connected to a second communication port of the first pipeline, a second end of the third pipeline is connected to a second end of the second pipeline at a first position, a second isolation valve and a first regulating valve are sequentially arranged in the third pipeline along a direction from the first end to the second end of the third pipeline, and a diameter of the third pipeline is larger than a diameter of the second pipeline; a fourth pipeline, wherein a first end of the fourth pipeline is in communication with the first position, a second end of the fourth pipeline is a drain port, and the first position is a position between the flow limiting orifice plate and the first regulating valve; Among them, when a small or medium-sized rupture occurs in the primary cooling system or a steam generator heat transfer tube ruptures, the medium in the second pipeline is in a critical flow state, and the pipe diameter of the second pipeline is determined by simulation analysis based on the heat storage, decay heat and cooling rate requirements of the primary cooling system, and the aperture of the flow limiting orifice is determined based on the steam flow after the accident, the parameters of the first isolation valve and the pipeline characteristics of the second pipeline.

2. The secondary cooling system according to claim 1, characterized in that: The first isolation valve and the second isolation valve are both electric isolation valves, and the first regulating valve is an electric regulating valve.

3. The secondary cooling system according to claim 1, characterized in that: The second end of the fourth pipeline is communicated with the muffler.

4. The secondary cooling system according to claim 1, characterized in that: The first isolation valve, the second isolation valve and the first regulating valve are all electrically connected to a backup power supply.

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