Secondary side passive residual heat removal system

Abstract

The invention provides a secondary side passive residual heat removal system which is applied to a nuclear power station and comprises a steam generator, a steam pipeline, a condenser, a condensation backflow pipeline and a drainage pipeline, the inlet end of the drainage pipeline is communicated with the steam pipeline, and the outlet end of the drainage pipeline is communicated with the condensation backflow pipeline; the drain pipeline comprises a drain valve, and the drain valve is used for blocking steam from the steam pipeline and discharging condensate water in the steam pipeline into the condensate backflow pipeline under the condition that the drain valve is in an open state. The secondary side waste heat removal system can solve the problems that when the secondary side waste heat removal system is started, noise is large, and the pipeline and the heat exchanger are prone to being affected by condensate water in the steam pipeline to be damaged.

Description

Technical Field

[0001] The present application relates to the field of nuclear power plant safety technology, and in particular to a secondary side passive residual heat removal system. Background Art

[0002] As one of the three major safety functions of nuclear power plants, the heat removal function is usually implemented by a combination of multiple safety systems or equipment. Among them, the secondary side waste heat removal system, as the execution system of the heat removal function, plays an important role in the safety of nuclear power plants. However, the secondary side waste heat removal system designed with a passive concept in the prior art usually has a large noise at startup due to the presence of condensed water in the system pipelines, and the condensed water will impact the pipelines and heat exchangers, causing the pipelines and heat exchangers to vibrate violently, which can easily cause damage to the pipelines and heat exchangers. Summary of the invention

[0003] The purpose of the embodiments of the present application is to provide a secondary-side passive waste heat removal system to solve the problem that pipes and heat exchangers in the secondary-side waste heat removal system are easily damaged by condensed water.

[0004] In order to solve the above technical problems, this application is implemented as follows:

[0005] The embodiment of the present application provides a secondary side passive waste heat removal system, which is applied to a nuclear power plant, and includes a steam generator, a steam pipeline, a condenser, a condensate return pipeline, and a drain pipeline, wherein the outlet end of the steam generator is connected to the inlet end of the steam pipeline, the outlet end of the steam pipeline is connected to the inlet end of the condenser, the outlet end of the condenser is connected to the inlet end of the condensate return pipeline, the outlet end of the condensate return pipeline is connected to the inlet end of the steam generator, the inlet end of the drain pipeline is connected to the steam pipeline, and the outlet end of the drain pipeline is connected to the condensate return pipeline;

[0006] The drain line includes a drain valve, which is used to block the steam from the steam line and discharge the condensed water in the steam line into the condensate return line when the drain valve is in an open state.

[0007] Optionally, the steam pipeline comprises an inlet isolation valve and an inlet regulating stop valve, wherein the inlet isolation valve is arranged close to the inlet end of the steam pipeline, and the inlet regulating stop valve is arranged close to the outlet end of the steam pipeline.

[0008] Optionally, when the nuclear power plant is in normal operating conditions, the inlet isolation valve and the inlet regulating stop valve are both in a closed state.

[0009] Optionally, the steam pipeline includes a first pipeline, the first pipeline is arranged between the inlet isolation valve and the inlet regulating stop valve, and the heights of both ends of the first pipeline are higher than the heights of preset position points in the first pipeline;

[0010] Wherein, the inlet end of the hydrophobic pipeline intersects and communicates with a preset position point in the first pipeline.

[0011] Optionally, the steam pipeline includes a second pipeline, which is arranged between the condenser and the inlet regulating stop valve, and the height of one end of the second pipeline connected to the condenser is higher than the height of one end of the second pipeline connected to the inlet regulating stop valve.

[0012] Optionally, the drain pipeline includes a first isolation valve and a second isolation valve, the first isolation valve, the drain valve and the second isolation valve are sequentially arranged on the drain pipeline, and the second isolation valve is arranged close to the inlet end of the condensation reflux pipeline.

[0013] Optionally, the drain line further comprises a filter, and the filter is arranged between the first isolation valve and the drain valve.

[0014] Optionally, a reflux isolation valve is provided on the condensate reflux pipeline, and when the nuclear power plant is in normal operating conditions, the reflux isolation valve is in a closed state.

[0015] Optionally, the secondary side passive waste heat removal system also includes a containment shell, and the condensation reflux pipeline also includes a third pipeline and a fourth pipeline, the third pipeline is arranged outside the containment shell and connected to the condenser, and the fourth pipeline is arranged inside the containment shell and connected to the steam generator.

[0016] Optionally, the reflux isolation valve is provided on the third pipeline, and a reflux check valve is provided on the fourth pipeline.

[0017] In the embodiment of the present application, the secondary side passive waste heat removal system is optimized by adding a drain line. When the system is put into operation, the condensed water remaining in the steam line will be discharged into the drain line together with the steam, and the condensed water and steam will be separated by the drain valve in the drain line. In this way, the condensed water can be discharged from the drain line, which reduces the impact of the condensed water on the steam line, reduces the vibration of the pipeline, is conducive to the establishment of passive natural circulation on the secondary side, increases the heat carrying reliability of the secondary side, and improves the safety performance of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the description of the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0019] Figure 1 A schematic diagram of the structure of a secondary side passive waste heat removal system provided in an embodiment of the present application;

[0020] Figure 2 It is a structural schematic diagram of the secondary side passive residual heat removal system in standby state;

[0021] The reference numerals are as follows:

[0022] 10: Steam generator;

[0023] 20: Steam pipeline; 21: Inlet isolation valve; 22: Inlet regulating stop valve; 23: Preset position point;

[0024] 30: condenser;

[0025] 40: condensate reflux pipeline; 41: reflux isolation valve; 42: reflux check valve;

[0026] 50: Drain pipeline; 51: Drain valve; 52: First isolation valve; 53: Second isolation valve; 54: Third isolation valve; 55: Filter;

[0027] 60: containment;

[0028] 70: Main steam pipeline; 71: Steam isolation valve;

[0029] 80: water supply pipeline; 81: water supply isolation valve; 82: water supply check valve;

[0030] 90: Radiator tank; 91: Steam exhaust port. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0032] In the description of the present application, it should be understood that the terms "X-axis", "Y-axis", "Z-axis", "vertical", "parallel", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as

[0033] It is not interpreted as a limitation of the present application. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present application, unless otherwise specified, the meaning of "multiple" is two or more. In the description of the present application, it should be noted that, unless otherwise clearly specified and defined, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0034] The present application embodiment provides a secondary side passive residual heat removal system, which is applied to nuclear power plants. Figure 1 The secondary side passive waste heat removal system specifically includes: a steam generator 10, a steam pipeline 20, a condenser 30, a condensation reflux pipeline 40, and a drain pipeline 50. The outlet end of the steam generator 10 is connected to the inlet end of the steam pipeline 20, the outlet end of the steam pipeline 20 is connected to the inlet end of the condenser 30, the outlet end of the condenser 30 is connected to the inlet end of the condensation reflux pipeline 40, the outlet end of the condensation reflux pipeline 40 is connected to the inlet end of the steam generator 10, the inlet end of the drain pipeline 50 is connected to the steam pipeline 20, and the outlet end of the drain pipeline 50 is connected to the condensation reflux pipeline 40;

[0035] The drain line 50 includes a drain valve 51 . When the drain valve 51 is in an open state, it is used to block the steam from the steam line 20 and discharge the condensed water in the steam line 20 into the condensate return line 40 .

[0036] It should be noted that the secondary side passive residual heat removal system is applied to nuclear power plants and can be used to deal with the loss of secondary heat sink beyond the design basis accident. In the event of a power outage in the entire nuclear power plant and failure of the auxiliary feedwater system steam pump, the core residual heat is removed through the steam generator and the reactor coolant system equipment heat storage, maintaining the reactor in a safe state within 72 hours.

[0037] In a specific embodiment of the present application, a drain line 50 is added to the secondary side passive waste heat removal system, and the inlet end of the drain line 50 is arranged to be connected to the steam line 20, and the outlet end of the drain line 50 is arranged to be connected to the condensate return line 40. The condensate remaining in the steam line 20 can be connected to the drain line from the inlet end of the drain line 50, and the steam existing in the steam line 20 is blocked by the drain valve 51 in the drain line 50, and only the condensate passes through and enters the condensate return line 40 from the outlet end of the drain line 50.

[0038] Specifically, the condensed water in the steam pipeline 20 can be discharged into the drain pipeline 50 by the gravity of the condensed water. For example, the connection point between the drain pipeline 50 and the steam pipeline 20 is set as a low point, and the condensed water in the steam pipeline 20 converges to the low point under the action of gravity and enters the drain pipeline 50. At the same time, since water vapor is less affected by gravity, a low point is set in the steam pipeline 20, so that the condensed water in the steam pipeline 20 can be discharged into the drain pipeline 50 as much as possible, so as to reduce the influence of the flow of water vapor in the steam pipeline 20 on the condensed water, reduce the impact on the pipe wall caused by the movement of condensed water, and improve the safety performance of the system.

[0039] Optionally, the steam pipeline 20 includes an inlet isolation valve 21 and an inlet regulating stop valve 22 , wherein the inlet isolation valve 21 is disposed close to the inlet end of the steam pipeline 20 , and the inlet regulating stop valve 22 is disposed close to the outlet end of the steam pipeline 20 .

[0040] In a specific implementation, an inlet isolation valve 21 and an inlet regulating stop valve 22 are provided on the steam pipeline 20 to facilitate the regulation of the discharge of the secondary side waste heat through the steam pipeline 20. The inlet isolation valve 21 is opened, and the water vapor generated in the steam generator 10 enters the steam pipeline 20. By regulating the opening of the inlet regulating stop valve 22, the rate at which the water vapor enters the condenser 30 from the steam pipeline 20 can be regulated, preventing the water vapor from directly entering the condenser 30 through the steam pipeline 20, avoiding excessive impact of the water vapor on the pipes in the steam pipeline 20 and the condenser 30, and improving the safety of the system.

[0041] Optionally, when the nuclear power plant is in normal operation, the inlet isolation valve 21 and the inlet regulating stop valve 22 are both in a closed state.

[0042] See also Figure 2 When the nuclear power plant is in normal operation, the water supply isolation valve 81 and the water supply check valve 82 of the water supply pipeline 80 can be opened to supply water to the steam generator 10 from the water supply pipeline 80. The steam isolation valve 71 can be opened to discharge the steam converted by the steam generator 10 from the main steam pipeline 70. Since the nuclear power plant is in normal operation, the secondary side passive residual heat removal system can be in a closed state. Therefore, the inlet isolation valve 21 and the inlet regulating stop valve 22 can be closed to prevent water vapor from entering the steam pipeline 20.

[0043] Optionally, the steam pipeline 20 includes a first pipeline, the first pipeline is arranged between the inlet isolation valve 21 and the inlet regulating stop valve 22, and the heights of both ends of the first pipeline are higher than the height of a preset position point 23 in the first pipeline;

[0044] The inlet end of the drain line 50 intersects and communicates with a preset position point 23 in the first pipeline.

[0045] In a specific embodiment of the present application, in order to allow the condensed water retained in the steam pipeline 20 to be discharged into the drain pipeline 50 as much as possible, a preset position point can be set in the first pipeline of the steam pipeline 20, and the preset position point 23 can be the middle position point of the first pipeline, which is set at the middle position point between the inlet isolation valve 21 and the inlet regulating stop valve 22. It can also be other positions in the first pipeline except the positions of the inlet isolation valve 21 and the inlet regulating stop valve 22. At the same time, the position height of the preset position point 23 should be lower than the height of the position where the inlet isolation valve 21 is located, and should also be lower than the height of the position where the inlet regulating stop valve 22 is located. In this way, the condensed water in the steam pipeline 20 can flow to the preset position point 23 under the action of gravity, and then flow into the drain pipeline 50.

[0046] Optionally, the steam pipeline 20 includes a second pipeline, which is arranged between the condenser 30 and the inlet regulating stop valve 22, and the height of one end of the second pipeline connected to the condenser 30 is higher than the height of one end of the second pipeline connected to the inlet regulating stop valve 22.

[0047] In another embodiment of the present application, in order to allow the condensed water in the steam pipeline 20 to be discharged into the drain pipeline 50 as much as possible and avoid being retained in the steam pipeline 20, a pipeline between the condenser 30 and the inlet regulating stop valve 22, i.e., a second pipeline, may also be provided with a slope. Among them, the end of the second pipeline connected to the condenser 30 may be higher than the end of the second pipeline connected to the inlet regulating stop valve 22, and the condensed water flows toward the inlet regulating stop valve 22 under the action of gravity, flows into the above-mentioned first pipeline, and flows to the preset position point 23 through the first pipeline, and finally remains in the drain pipeline 50. Specifically, the slope of the above-mentioned second pipeline can be set to 2 / 1000 or 3 / 1000. This application does not make specific restrictions and can be set according to actual conditions.

[0048] Optionally, the drain line 50 includes a first isolation valve 52 and a second isolation valve 53, the first isolation valve 52, the drain valve 51 and the second isolation valve 53 are sequentially arranged on the drain line 50, and the second isolation valve 53 is arranged close to the inlet end of the condensation reflux line 40.

[0049] In the embodiment of the present application, the drain line 50 may also be provided with a first isolation valve 52 and a second isolation valve 53, so as to control whether the condensed water enters the drain line 50 and whether it is discharged from the drain line 50. In addition, an external pipeline may be connected between the drain valve 51 and the second isolation valve 53, and a third isolation valve 54 may be provided on the pipeline. When the third isolation valve 54 is opened, the condensed water in the drain line 50 can be discharged from the system. When the third isolation valve 54 is closed, the condensed water in the drain line 50 can enter the condensation reflux pipeline 40 through the second isolation valve 53, and enter the steam generator 10 for circulation.

[0050] Optionally, the drain line 50 further includes a filter 55 , and the filter 55 is disposed between the first isolation valve 52 and the drain valve 51 .

[0051] It can be understood that the filter 55 is arranged before the steam trap to remove impurities in the condensed water, so as to facilitate the impurities to flow into the steam trap 51 and avoid affecting the normal use of the steam trap 51.

[0052] Optionally, a reflux isolation valve 41 is provided on the condensate reflux pipeline 40 , and when the nuclear power plant is in normal operation, the reflux isolation valve 41 is in a closed state.

[0053] In one embodiment of the present application, similar to the above-mentioned nuclear power plant being in normal operation with the inlet isolation valve 21 and the inlet regulating stop valve 22 closed, the steam generator 10 can now only interact with the main steam pipeline 70 and the feedwater pipeline 80. Therefore, the condensate return pipeline 40 can be in a closed state. By closing the return isolation valve 41, the water in the condensate return pipeline 40 can be prohibited from entering the steam generator 10.

[0054] Optionally, the secondary side passive waste heat removal system also includes a containment shell 60, and the condensation reflux pipeline 40 also includes a third pipeline and a fourth pipeline, the third pipeline is arranged outside the containment shell 60 and connected to the condenser 30, and the fourth pipeline is arranged inside the containment shell 60 and connected to the steam generator 10.

[0055] Optionally, the third pipeline is provided with the backflow isolation valve 41 , and the fourth pipeline is provided with a backflow check valve 42 .

[0056] It is worth mentioning that the reflux isolation valve 41 provided on the third pipeline can control whether the condensed water in the condensation reflux pipeline 40 enters the steam generator 10 for circulation, and the reflux check valve 42 provided on the fourth pipeline can prevent the water in the steam generator 10 from flowing back into the condensation reflux pipeline 40. In addition, since the reflux check valve 42 is to prevent the water in the steam generator 10 from flowing back, the reflux check valve 42 can be provided at a position close to the inlet end of the steam generator 10, and can be provided inside the containment 60. Since the reflux isolation valve 41 needs to be regulated, it can be provided outside the containment 60, so that the staff can control it easily.

[0057] In another specific embodiment of the present application, the nuclear power plant staff can improve the safety performance of the system by controlling the commissioning of the secondary side passive residual heat removal system to avoid the impact of condensed water in the steam pipeline 20 on the pipeline and the heat exchanger. The specific commissioning sequence can be:

[0058] Open the inlet regulating stop valve 22 and open the reflux isolation valve 41; open the first isolation valve 52 and the second isolation valve 53; after the condensed water in the steam pipeline 20 is drained, reduce the opening of the inlet regulating stop valve 22 to a smaller opening; slowly open the inlet isolation valve 21; increase the opening of the inlet regulating stop valve 22.

[0059] In the above embodiment, the inlet regulating stop valve 22 is first opened to gather the condensed water and condensate water retained in the steam pipeline 20 to the preset position point 23 in the steam pipeline 20 and discharge it into the drain pipeline 50. Subsequently, the first isolation valve 52 and the second isolation valve 53 are opened to allow the condensed water to enter the drain pipeline 50 and be discharged outside the system through the drain valve 51 or enter the condensate return pipeline 40. Under the action of the drain pipeline 50, the condensed water in the steam pipeline 20 is emptied. At this time, the inlet regulating stop valve 22 can be adjusted to a smaller opening. At this time, the inlet isolation valve 21 is slowly opened, which can effectively reduce the impact of water vapor from the steam generator 10 on the pipes in the steam pipeline 20. Finally, the opening of the inlet regulating stop valve 22 is adjusted again to find the heat-carrying cycle in the secondary side passive residual heat removal system and maintain a relatively stable state to meet the needs of nuclear power plant core heat-carrying and improve heat-carrying reliability.

[0060] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0061] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A secondary side passive residual heat removal system, applied to a nuclear power plant, characterized in that: It comprises a steam generator, a steam pipeline, a condenser, a condensation reflux pipeline and a drain pipeline, wherein the outlet end of the steam generator is connected to the inlet end of the steam pipeline, the outlet end of the steam pipeline is connected to the inlet end of the condenser, the outlet end of the condenser is connected to the inlet end of the condensation reflux pipeline, the outlet end of the condensation reflux pipeline is connected to the inlet end of the steam generator, the inlet end of the drain pipeline is connected to the steam pipeline, and the outlet end of the drain pipeline is connected to the condensation reflux pipeline; The drain line includes a drain valve, which is used to block the steam from the steam line and discharge the condensed water in the steam line into the condensate return line when the drain valve is in an open state.

2. The secondary side passive residual heat removal system according to claim 1, characterized in that: The steam pipeline comprises an inlet isolation valve and an inlet regulating stop valve. The inlet isolation valve is arranged close to the inlet end of the steam pipeline, and the inlet regulating stop valve is arranged close to the outlet end of the steam pipeline.

3. The secondary side passive residual heat removal system according to claim 2, characterized in that: When the nuclear power plant is in normal operation, the inlet isolation valve and the inlet regulating stop valve are both in a closed state.

4. The secondary side passive residual heat removal system according to claim 2, characterized in that: The steam pipeline comprises a first pipeline, the first pipeline is arranged between the inlet isolation valve and the inlet regulating stop valve, and the heights of both ends of the first pipeline are higher than the heights of preset positions in the first pipeline; Wherein, the inlet end of the hydrophobic pipeline intersects and is connected with a preset position point in the first pipeline.

5. The secondary side passive residual heat removal system according to claim 2, characterized in that: The steam pipeline includes a second pipeline, which is arranged between the condenser and the inlet regulating stop valve, and the height of one end of the second pipeline connected to the condenser is higher than the height of one end of the second pipeline connected to the inlet regulating stop valve.

6. The secondary side passive residual heat removal system according to claim 1, characterized in that: The drain pipeline comprises a first isolation valve and a second isolation valve. The first isolation valve, the drain valve and the second isolation valve are sequentially arranged on the drain pipeline. The second isolation valve is arranged close to the inlet end of the condensation reflux pipeline.

7. The secondary side passive residual heat removal system according to claim 6, characterized in that: The drain line further includes a filter disposed between the first isolation valve and the drain valve.

8. The secondary side passive residual heat removal system according to claim 2, characterized in that: The condensate reflux pipeline is provided with a reflux isolation valve, and when the nuclear power plant is in normal operation, the reflux isolation valve is in a closed state.

9. The secondary side passive residual heat removal system according to claim 8, characterized in that: The secondary side passive waste heat removal system also includes a containment shell, and the condensation reflux pipeline also includes a third pipeline and a fourth pipeline. The third pipeline is arranged outside the containment shell and connected to the condenser, and the fourth pipeline is arranged inside the containment shell and connected to the steam generator.

10. The secondary side passive residual heat removal system according to claim 9, characterized in that: The third pipeline is provided with the backflow isolation valve, and the fourth pipeline is provided with a backflow check valve.

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