A steam generator accident protection system and its working method

Abstract

The present invention discloses a steam generator accident protection system and its working method. The pipe-side outlet of the steam generator is connected to the steam output pipeline via a steam rapid isolation valve. An emergency drain valve is provided on the pipeline between the water supply rapid isolation valve and the steam generator. An atmospheric release valve is provided between the steam generator and the steam rapid isolation valve. The outlet of the inlet sodium valve is connected to the sodium inlet of the steam generator shell side, the inlet of the outlet sodium valve is connected to the sodium outlet of the steam generator shell side, and a flow differential meter is connected to the outlet of the inlet sodium valve and the inlet of the outlet sodium valve. A steam generator air cavity is provided at the upper portion of the steam generator shell side, a hydrogen-in-gas meter is installed at the top of the steam generator air cavity, and a hydrogen-in-sodium meter is installed at the lower portion of the steam generator shell side. This system and its working method can timely monitor small leaks and prevent contamination of the main circuit coolant in the event of a large leak.

Description

Technical Field

[0001] The present invention belongs to the field of steam generator accident protection, and in particular relates to a steam generator accident protection system and a working method thereof. Background Art

[0002] The accident design of the steam generator of a reactor cooled by liquid metal (lithium or sodium) is different from the current mainstream water-cooled reactor. The leakage of the heat transfer tube will cause the liquid metal (lithium or sodium) and water (or water vapor) to react chemically, generating hydrogen and releasing heat, resulting in a severe pressure transient shock in the system. Therefore, in the overall design of the steam generator of a reactor cooled by liquid metal (lithium or sodium), it is required that small leaks should be detected in a timely manner, and the alarm signal for small leaks should be highly reliable and isolated from the main circuit in a timely manner. The design requirements for large leak conditions are a reliable large leak signal to prevent the circuit pressure from rising to the allowable limit; the fault module should be isolated in time to prevent the main circuit coolant from being contaminated. The steam generator accident protection system of a reactor using liquid metal (lithium or sodium) as a coolant should have the functions of monitoring and overpressure protection, isolating and discharging, and containing sodium-water reaction products. However, no similar disclosure is given in the prior art. Summary of the Invention

[0003] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a steam generator accident protection system and a working method thereof, which can timely monitor small leaks and prevent the main circuit coolant from being contaminated in the event of large leaks.

[0004] To achieve the above-mentioned object, the steam generator accident protection system of the present invention comprises a water supply pipe, a water supply rapid isolation valve, a steam generator, a steam rapid isolation valve, a steam output pipe, an atmospheric release valve, an inlet sodium valve, an outlet sodium valve, a flow differential meter, an accident sodium discharge valve, a primary discharge tank and a bursting disk;

[0005] The water supply pipeline is connected to the pipe side inlet of the steam generator through the water supply quick isolation valve, and the pipe side outlet of the steam generator is connected to the steam output pipeline through the steam quick isolation valve. An emergency drain valve is installed on the pipeline between the water supply quick isolation valve and the steam generator; the atmospheric release valve is installed between the steam generator and the steam quick isolation valve.

[0006] The outlet of the inlet sodium valve is connected to the sodium inlet of the steam generator shell side, the inlet of the outlet sodium valve is connected to the sodium outlet of the steam generator shell side, and the flow differential meter is connected to the outlet of the inlet sodium valve and the inlet of the outlet sodium valve;

[0007] A steam generator air cavity is provided at the upper part of the steam generator shell side, a gas hydrogen meter is installed on the top of the steam generator air cavity, and a sodium hydrogen meter is installed at the lower part of the steam generator shell side, wherein the sodium hydrogen meter is located below the sodium liquid level on the steam generator shell side.

[0008] Bubble noise detectors are installed on the upper and lower sides of the steam generator shell.

[0009] The bottom outlet of the steam generator shell side is connected to the first-level discharge tank through an emergency sodium discharge valve.

[0010] The outlet on the bottom side of the steam generator is connected to the first-level discharge tank through a bursting membrane.

[0011] It also includes an argon supply system and an argon supply valve; the argon supply system is connected to the steam generator air cavity through the argon supply valve.

[0012] It also includes a secondary discharge tank and a sodium vapor cold trap; the top outlet of the primary discharge tank is connected to the upper inlet of the secondary discharge tank, the bottom outlet of the secondary discharge tank is connected to the inlet of the primary discharge tank, and the outlet of the secondary discharge tank is connected to the sodium vapor cold trap.

[0013] Several temperature sensors are installed on the pipe between the bursting disk and the primary discharge tank.

[0014] The number of temperature sensors is four, and the number of flow differential meters is four.

[0015] The number of hydrogen counters in gas and the number of hydrogen counters in sodium are both two.

[0016] The outlet of the emergency drain valve is connected to a drain expansion tank.

[0017] A method for operating a steam generator accident protection system, comprising:

[0018] 1) Steam generator small leakage condition

[0019] Determine whether a small leak occurs in the steam generator based on the data detected by two sodium hydrogen meters, two gas hydrogen meters, and two bubble noise detectors;

[0020] When a small leak occurs in the steam generator, the steam rapid isolation valve and the water rapid isolation valve are closed, and the inlet and outlet sodium valves are closed at the same time. The atmospheric relief valve is opened to exhaust and depressurize the steam generator pipe side. When the pressure on the steam generator pipe side drops to the preset pressure value, the atmospheric relief valve is automatically closed and the emergency drain valve is opened to drain the water on the steam generator pipe side.

[0021] At the same time, the sodium in the shell side of the steam generator is discharged into the primary discharge tank through the emergency sodium discharge valve;

[0022] 2) Steam generator large leakage condition

[0023] Determine whether a major leak occurs in the steam generator based on the data detected by four flow differential meters and four temperature sensors;

[0024] When a large leak occurs in the steam generator, close the steam rapid isolation valve, water rapid isolation valve, inlet sodium valve and outlet sodium valve, open the atmospheric relief valve, and exhaust and depressurize the steam generator pipe side. When the pressure on the steam generator pipe side is lower than the preset pressure value, the atmospheric relief valve automatically closes, and the emergency drain valve automatically opens and closes according to the steam and water pressure on the steam generator pipe side to discharge the remaining steam and water on the steam generator pipe side;

[0025] The mixture of sodium, hydrogen and sodium vapor discharged from the steam generator flows into the primary discharge tank.

[0026] In step 1), when the data detected by any two of the two sodium hydrogen meters and the two gas hydrogen meters exceed the standard, it indicates that a small leak occurs in the steam generator; when the data detected by one of the two bubble noise detectors exceeds the standard and the data detected by the two sodium hydrogen meters and the two gas hydrogen meters exceed the standard, it indicates that a small leak occurs in the steam generator.

[0027] When the flow data detected by two of the four flow differential meters exceeds the preset flow deviation alarm value, it indicates that a major leak has occurred in the steam generator;

[0028] When the temperatures detected by more than two temperature sensors exceed the temperature deviation alarm value, it indicates that a major leak has occurred in the steam generator.

[0029] The present invention has the following beneficial effects:

[0030] The steam generator accident protection system and its operating method, described herein, utilize a diverse and redundant combination of a sodium hydrogen meter, a gas hydrogen meter, and a bubble noise detector to reliably monitor small steam generator leaks and provide fault control in the event of a steam generator leak. Furthermore, the system utilizes a dual mechanism of action, including the steam generator's air cavity and bursting disk, to effectively mitigate pressure transients during large leaks, helping to ensure the safe operation of the steam generator and connected equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a structural schematic diagram of the present invention.

[0032] Among them, 1 is the inlet sodium valve, 2 is the steam generator, 3 is the steam generator air cavity, 4 is the outlet sodium valve, 4-1 is the flow difference meter, 5 is the steam rapid isolation valve, 6 is the atmospheric release valve, 7 is the water supply rapid isolation valve, 8 is the emergency drain valve, 9 is the hydrophobic expansion tank, 10 is the bursting membrane, 10-1 is the temperature sensor, 11 is the emergency sodium discharge valve, 12 is the first-level discharge tank, 13 is the second-level discharge tank, 14 is the sodium vapor cold trap, 15-1 is the sodium hydrogen meter, 15-2 is the gas hydrogen meter, 16 is the bubble noise detector, 17 is the argon supply system, and 18 is the argon supply valve. DETAILED DESCRIPTION

[0033] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only embodiments of a part of the present invention, not all embodiments, and are not intended to limit the scope of the present invention. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts disclosed in the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of protection of the present invention.

[0034] The accompanying drawings illustrate schematic diagrams of the structures of the disclosed embodiments of the present invention. These figures are not drawn to scale; for the purpose of clarity, some details are exaggerated and some details may be omitted. The shapes of the various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are merely exemplary and may deviate in practice due to manufacturing tolerances or technical limitations. Those skilled in the art may design regions / layers with different shapes, sizes, and relative positions as needed.

[0035] refer to Figure 1 The steam generator accident protection system of the present invention includes a water supply pipeline, a water supply rapid isolation valve 7, a steam generator 2, a steam rapid isolation valve 5, a steam output pipeline, an atmospheric release valve 6, an inlet sodium valve 1, an outlet sodium valve 4, a flow differential meter 4-1, an accident sodium discharge valve 11, a primary discharge tank 12 and a bursting disk 10;

[0036] The water supply pipeline is connected to the pipe side inlet of the steam generator 2 through the water supply rapid isolation valve 7, and the pipe side outlet of the steam generator 2 is connected to the steam output pipeline through the steam rapid isolation valve 5. An emergency drain valve 8 is provided on the pipeline between the water supply rapid isolation valve 7 and the steam generator 2, and the outlet of the emergency drain valve 8 is connected to the hydrophobic expansion tank 9; the atmospheric release valve 6 is provided between the steam generator 2 and the steam rapid isolation valve 5.

[0037] The outlet of the inlet sodium valve 1 is connected to the sodium inlet on the shell side of the steam generator 2, the inlet of the outlet sodium valve 4 is connected to the sodium outlet on the shell side of the steam generator 2, and the four flow difference meters 4-1 are connected to the outlet of the inlet sodium valve 1 and the inlet of the outlet sodium valve 4. The flow deviation action constant is 20%.

[0038] A steam generator air cavity 3 is provided at the upper part of the shell side of the steam generator 2. The argon supply system 17 is connected to the steam generator air cavity 3 through the argon supply valve 18. Two gas hydrogen meters 15-2 are installed on the top of the steam generator air cavity 3. Two sodium hydrogen meters 15-1 are installed at the lower part of the shell side of the steam generator 2. Each sodium hydrogen meter 15-1 is located below the sodium liquid level on the shell side of the steam generator 2.

[0039] Bubble noise detectors 16 are installed on the upper and lower sides of the shell side of the steam generator 2.

[0040] The bottom outlet of the shell side of the steam generator 2 is connected to the first-level discharge tank 12 through the emergency sodium discharge valve 11, the top outlet of the first-level discharge tank 12 is connected to the upper inlet of the second-level discharge tank 13, the bottom outlet of the second-level discharge tank 13 is connected to the inlet of the first-level discharge tank 12, and the outlet of the second-level discharge tank 13 is connected to the sodium vapor cold trap 14.

[0041] The outlet on the bottom side of the steam generator 2 is connected to the first-level discharge tank 12 through the bursting membrane 10. Several temperature sensors 10-1 are installed on the pipeline between the bursting membrane 10 and the first-level discharge tank 12, among which the temperature deviation action value is 100℃.

[0042] The working method of the steam generator accident protection system of the present invention comprises the following steps:

[0043] 1) Steam generator 2 has a small leak

[0044] Determine whether a small leak occurs in the steam generator 2 based on the data detected by the two sodium hydrogen meters 15-1, the data detected by the two gas hydrogen meters 15-2, and the data detected by the two bubble noise detectors 16. When the data detected by any two of the two sodium hydrogen meters 15-1 and the two gas hydrogen meters 15-2 exceed the standard, it indicates that a small leak occurs in the steam generator 2; when the data detected by one of the two bubble noise detectors 16 exceeds the standard and the data detected by one of the two sodium hydrogen meters 15-1 and the two gas hydrogen meters 15-2 exceed the standard, it indicates that a small leak occurs in the steam generator 2;

[0045] When a small leak occurs in the steam generator 2, the steam rapid isolation valve 5 and the water rapid isolation valve 7 are closed, and the inlet sodium valve 1 and the outlet sodium valve 4 are closed at the same time, and the atmospheric relief valve 6 is opened to quickly exhaust steam and relieve pressure on the pipe side of the steam generator 2. When the pressure on the pipe side of the steam generator 2 drops to a preset pressure value, the atmospheric relief valve 6 is automatically closed, and the emergency drain valve 8 is opened to drain the water on the pipe side of the steam generator 2 into the drain expansion tank 9;

[0046] At the same time, the argon supply valve 18 is opened. Under the pressure of argon, the sodium in the shell side of the steam generator 2 is discharged into the primary discharge tank 12 through the emergency sodium discharge valve 11. The argon pressure is higher than the pressure on the steam-water side, so as to accelerate the sodium discharge speed and reduce the amount of water leaking in.

[0047] 2) Steam generator 2 major leakage conditions

[0048] When a major leak occurs in the steam generator 2, a violent sodium-water reaction occurs inside the steam generator 2, forming a violent pressure transient, and a huge deviation occurs in the sodium flow rate at the inlet and outlet of the steam generator 2. That is, when the flow data detected by two of the four flow difference meters 4-1 exceeds the preset flow deviation alarm value, it indicates that a major leak has occurred in the steam generator 2;

[0049] At this time, the steam generator air cavity 3 can compensate for some of the transient pressure impact. When the internal pressure on the shell side of the steam generator 2 exceeds the action value of the bursting disk 10, the sodium in the shell side of the steam generator 2 is discharged into the primary discharge tank 12 through the bursting disk 10. At this time, the temperature detected by the four temperature sensors 10-1 rises. If the temperature detected by more than two temperature sensors 10-1 exceeds the temperature deviation alarm value, it indicates that a major leak has occurred in the steam generator 2.

[0050] At this time, close the steam rapid isolation valve 5, the water rapid isolation valve 7, the inlet sodium valve 1 and the outlet sodium valve 4, open the atmospheric relief valve 6, and quickly exhaust the steam and water on the pipe side of the steam generator 2 to relieve the pressure. After the pressure on the pipe side of the steam generator 2 is lower than the preset pressure value, the atmospheric relief valve 6 automatically closes, and the subsequent emergency drain valve 8 automatically opens and closes according to the pressure on the steam and water side of the steam generator 2 to discharge the remaining steam and water on the pipe side of the steam generator 2;

[0051] The mixture of sodium, hydrogen and sodium vapor discharged from the steam generator 2 flows into the primary discharge tank 12, wherein the hydrogen and sodium vapor form a mixed gas and enter the secondary discharge tank 13 through the top of the primary discharge tank 12, wherein most of the sodium vapor is condensed and separated in the secondary discharge tank 13, and refluxed through the bottom of the secondary discharge tank 13 to be discharged into the primary discharge tank 12, and the remaining sodium vapor is condensed and collected in the sodium vapor cold trap 14, and the hydrogen generated by the sodium-water reaction is discharged into the atmosphere;

[0052] After a large leak occurs, in order to quickly discharge sodium, the emergency sodium discharge valve 11 can be opened at the same time to discharge the sodium in the shell side of the steam generator 2 into the primary discharge tank 12. During the sodium discharge process, the argon supply valve 18 is opened, and the argon gas output by the argon supply system 17 provides power to quickly discharge the sodium in the shell side of the steam generator 2 while reducing the amount of water leaking in.

Claims

1. A steam generator accident protection system, characterized in that: It includes a water supply pipeline, a water supply rapid isolation valve (7), a steam generator (2), a steam rapid isolation valve (5), a steam output pipeline, an atmospheric release valve (6), an inlet sodium valve (1), an outlet sodium valve (4), a flow differential meter (4-1), an emergency sodium discharge valve (11), a primary discharge tank (12) and a bursting disk (10); The water supply pipeline is connected to the pipe side inlet of the steam generator (2) through the water supply rapid isolation valve (7), and the pipe side outlet of the steam generator (2) is connected to the steam output pipeline through the steam rapid isolation valve (5). An emergency drain valve (8) is provided on the pipeline between the water supply rapid isolation valve (7) and the steam generator (2); and an atmospheric release valve (6) is provided between the steam generator (2) and the steam rapid isolation valve (5). The outlet of the inlet sodium valve (1) is connected to the sodium inlet of the shell side of the steam generator (2), the inlet of the outlet sodium valve (4) is connected to the sodium outlet of the shell side of the steam generator (2), and the flow differential meter (4-1) is connected to the outlet of the inlet sodium valve (1) and the inlet of the outlet sodium valve (4); A steam generator air cavity (3) is provided at the upper portion of the shell side of the steam generator (2), a gas hydrogen meter (15-2) is installed at the top of the steam generator air cavity (3), and a sodium hydrogen meter (15-1) is installed at the lower portion of the shell side of the steam generator (2), wherein the sodium hydrogen meter (15-1) is located below the sodium liquid level on the shell side of the steam generator (2); Bubble noise detectors (16) are installed on the upper and lower sides of the shell side of the steam generator (2); The bottom outlet of the shell side of the steam generator (2) is connected to the first-stage discharge tank (12) through the emergency sodium discharge valve (11); The outlet on the bottom side of the steam generator (2) is connected to the first-stage discharge tank (12) through the bursting membrane (10); It also includes an argon supply system (17) and an argon supply valve (18); the argon supply system (17) is connected to the steam generator air cavity (3) via the argon supply valve (18); The invention also comprises a secondary discharge tank (13) and a sodium vapor cold trap (14); the top outlet of the primary discharge tank (12) is connected to the upper inlet of the secondary discharge tank (13), the bottom outlet of the secondary discharge tank (13) is connected to the inlet of the primary discharge tank (12), and the outlet of the secondary discharge tank (13) is connected to the sodium vapor cold trap (14).

2. The steam generator accident protection system according to claim 1, characterized in that: A plurality of temperature sensors (10-1) are installed on the pipeline between the bursting membrane (10) and the primary discharge tank (12).

3. The steam generator accident protection system according to claim 2, characterized in that: The number of temperature sensors (10-1) is four, and the number of flow differential meters (4-1) is four.

4. The steam generator accident protection system according to claim 3, characterized in that: The number of hydrogen counters in gas (15-2) and the number of hydrogen counters in sodium (15-1) are both two.

5. The steam generator accident protection system according to claim 1, characterized in that: The outlet of the emergency drain valve (8) is connected to a drain expansion tank (9).

6. A method for operating the steam generator accident protection system according to claim 3, characterized in that: include: 1) Steam generator (2) Small leakage condition Determining whether a small leak occurs in the steam generator (2) based on data detected by two sodium hydrogen meters (15-1), data detected by two gas hydrogen meters (15-2), and data detected by two bubble noise detectors (16); When a small leak occurs in the steam generator (2), the steam rapid isolation valve (5) and the water supply rapid isolation valve (7) are closed, and the inlet sodium valve (1) and the outlet sodium valve (4) are closed at the same time, and the atmospheric relief valve (6) is opened to exhaust the steam and drain the pressure on the pipe side of the steam generator (2). When the pressure on the pipe side of the steam generator (2) drops to a preset pressure value, the atmospheric relief valve (6) is automatically closed, and the emergency drain valve (8) is opened to drain the water on the pipe side of the steam generator (2); At the same time, the sodium in the shell side of the steam generator (2) is discharged into the primary discharge tank (12) through the emergency sodium discharge valve (11); 2) Steam generator (2) Large leakage condition Determining whether a major leak occurs in the steam generator (2) based on data detected by four flow differential meters (4-1) and data detected by four temperature sensors (10-1); When a large leak occurs in the steam generator (2), the steam rapid isolation valve (5), the water supply rapid isolation valve (7), the inlet sodium valve (1) and the outlet sodium valve (4) are closed, and the atmospheric relief valve (6) is opened to discharge steam and water from the pipe side of the steam generator (2) to relieve the pressure. After the pressure on the pipe side of the steam generator (2) is lower than the preset pressure value, the atmospheric relief valve (6) is automatically closed, and the emergency drainage valve (8) is automatically opened and closed according to the pressure on the steam and water side of the steam generator (2) pipe side to discharge the remaining steam and water from the pipe side of the steam generator (2); The mixture of sodium, hydrogen and sodium vapor discharged from the steam generator (2) flows into the primary discharge tank (12).

7. The working method of the steam generator accident protection system according to claim 6, characterized in that: In step 1), when the data detected by any two of the two sodium hydrogen meters (15-1) and the two gas hydrogen meters (15-2) exceed the standard, it indicates that a small leak occurs in the steam generator (2); when the data detected by one of the two bubble noise detectors (16) exceeds the standard and the data detected by one of the two sodium hydrogen meters (15-1) and the two gas hydrogen meters (15-2) exceed the standard, it indicates that a small leak occurs in the steam generator (2).

8. The operating method of the steam generator accident protection system according to claim 6, characterized in that: When the flow data detected by two of the four flow difference meters (4-1) exceed the preset flow deviation alarm value, it indicates that a large leak occurs in the steam generator (2); When the temperatures detected by more than two temperature sensors (10-1) exceed the temperature deviation alarm value, it indicates that a major leak has occurred in the steam generator (2).

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