Secondary loop system of nuclear power station

Abstract

The utility model relates to a secondary loop system of a nuclear power station, which realizes efficient heat energy recovery by introducing a condensing device and a compound heater in the system, thereby improving the energy utilization efficiency of the whole system. Meanwhile, liquid pumped out by the condensate pump can be guided to the U-shaped pipe only through the water seal pipe and the isolating valve, so that the U-shaped pipe is cooled to form water seal to isolate the condenser and the steam loop, steam in the steam loop can be accumulated for a longer time, the situation that the steam is directly discharged into the condenser after quickly penetrating through the steam loop is avoided, and the service life of the condenser is prolonged. Afterheat of steam discharged by the steam turbine is fully utilized, and the afterheat utilization rate of the secondary loop during high-power operation is effectively improved; furthermore, the cost and the installation of the water sealing pipe and the isolating valve are very simple, and an original secondary loop system does not need to be greatly improved, so that the improvement convenience of the waste heat utilization rate is simplified, and the problem that the cost is excessively increased due to the improvement of the waste heat utilization rate is also avoided.

Description

Technical Field

[0001] The utility model relates to the field of nuclear power, in particular to the secondary loop system of a nuclear power plant. Background Art

[0002] In the secondary loop system of a nuclear power plant, as one of the important heat exchange devices, the compound low-pressure heater plays a key role in improving the efficiency of the entire thermal system. Such heaters are usually designed to be able to heat condensate water and condense the steam discharged from the steam turbine, so as to realize the effective utilization of thermal energy.

[0003] During operation, after the condensate water comes out of the condenser, it first passes through the water side of the compound low-pressure heater, is heated to water at a higher temperature, and then flows to the subsequent process to be heated into steam. After the steam does work in the steam turbine, it is condensed back into water through the steam side of the compound low-pressure heater, and finally returns to the condenser through the drain pipe; in this process, the remaining heat of the steam discharged from the steam turbine can correspondingly improve the heat exchange efficiency of the compound low-pressure heater.

[0004] However, when working at high power, the steam discharged from the steam turbine will flow through the compound low-pressure heater quickly, resulting in a very low utilization rate of the waste heat of the steam, reducing the overall heat exchange efficiency of the secondary loop, and further affecting the work efficiency of the entire unit. Further, the mechanisms for improving the waste heat utilization rate commonly used in related technologies are often too complex and not easy to install. Especially for the high-requirement working conditions in the field of nuclear power, the installation cost of installing such waste heat improvement mechanisms will be too high. Summary of the Utility Model

[0005] The technical problem to be solved by the utility model is to provide a secondary loop system of a nuclear power plant, which can solve the problems of low waste heat utilization rate, too complex improvement of waste heat utilization rate, difficult installation and too high cost when working at high power.

[0006] The utility model provides a secondary loop system of a nuclear power plant, which includes:

[0007] A condensation device, which includes a condenser and a U-shaped tube that are communicated with each other;

[0008] A compound heater, which has a steam circuit and a water circuit, and the steam circuit and the water circuit exchange heat inside the compound heater. The steam inlet of the steam circuit is communicated with the steam turbine, and the steam outlet of the steam circuit is communicated with the U-shaped tube;

[0009] A condensate pump, the pump inlet end of which is communicated with the bottom of the condenser, and the pump outlet end of which is communicated with the water inlet end of the water circuit; and

[0010] A water seal maintaining device, the water seal maintaining device comprising a water seal pipe and an isolation valve, one end of the water seal pipe communicating with the U-shaped pipe, the other end of the U-shaped pipe communicating with the pump outlet end, and the isolation valve being disposed on the water seal pipe;

[0011] Wherein, the water seal pipe is used to guide the liquid pumped out by the condensate pump into the U-shaped pipe, so that a water seal is formed in the U-shaped pipe to isolate the condenser from the steam circuit.

[0012] Preferably, the secondary loop system of the nuclear power plant further comprises a pump-out pipeline, one end of the pump-out pipeline communicating with the pump outlet end, and the other end of the pump-out pipeline communicating with the inlet end.

[0013] Preferably, one end of the water seal pipe communicates with the U-shaped pipe, and the other end of the water seal pipe communicates with the pump-out pipeline.

[0014] Preferably, the diameter of the water seal pipe is smaller than the diameter of the pump-out pipeline; or

[0015] The water seal pipe is a capillary tube.

[0016] Preferably, the isolation valve includes a gate valve, a globe valve, a ball valve, a butterfly valve, a plug valve, a diaphragm valve or a needle valve.

[0017] Preferably, the isolation valve includes a manual valve, an electric valve, a pneumatic valve, a hydraulic valve or a solenoid valve.

[0018] Preferably, the secondary loop system of the nuclear power plant further comprises a tee, a first port of the tee communicating with the U-shaped pipe, a second port of the tee communicating with the bottom of the condenser, and a third port of the tee communicating with the side wall of the condenser.

[0019] Preferably, the water seal maintaining device comprises a plurality of water seal pipes and a plurality of isolation valves, each of the water seal pipes communicating with the U-shaped pipe and the pump outlet end, and each of the isolation valves being disposed on each of the water seal pipes in a one-to-one correspondence.

[0020] Implementing the present utility model has the following beneficial effects:

[0021] The present utility model relates to a secondary loop system of a nuclear power plant. By introducing a condensation device and a compound heater into the system, efficient heat energy recovery is achieved, thereby improving the energy utilization efficiency of the entire system.

[0022] Meanwhile, only a water seal pipe and an isolation valve are needed to guide the liquid pumped out by the condensate pump to the U-shaped pipe, so that the U-shaped pipe can be cooled to form a water seal to isolate the condenser from the steam circuit, enabling the steam in the steam circuit to accumulate for a longer time, preventing the steam from passing through quickly and being directly discharged into the condenser, and thus making full use of the waste heat of the steam discharged from the steam turbine, effectively improving the waste heat utilization rate of the secondary circuit during high-power operation; further, the costs and installations of both the water seal pipe and the isolation valve are very simple, and there is no need to make major modifications to the original secondary circuit system, simplifying the convenience of improving the waste heat utilization rate and avoiding excessive cost increases due to the improvement of waste heat utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The above and other objects, features, and advantages of the present invention will become more apparent by describing the exemplary embodiments of the present invention in more detail in conjunction with the accompanying drawings, wherein, in the exemplary embodiments of the present invention, the same reference numerals generally represent the same components.

[0024] Figure 1 It is a schematic structural diagram of the secondary circuit system of a nuclear power plant in some embodiments of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] The embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to make the present invention more thorough and complete, and to fully convey the scope of the present invention to those skilled in the art.

[0026] It should be understood that although the terms "first", "second", "third", etc. may be used in the present invention to describe various information, these information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present invention, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, the meaning of "a plurality" is two or more unless otherwise specifically defined.

[0027] In the description of the present utility model, it should be understood that the orientation or positional relationship indicated by terms such as "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present utility model.

[0028] Unless otherwise clearly specified and defined, terms such as "installation", "connection", "connection", "fixation", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0029] Figure 1 The secondary circuit system 10 of a nuclear power plant in some embodiments of the present utility model is shown. The secondary circuit system 10 of the nuclear power plant is used to transfer the heat in the primary side circuit (i.e., the reactor coolant system) to the steam generator, and finally generate steam to drive the steam turbine to rotate and generate electricity.

[0030] The secondary circuit system 10 of the nuclear power plant includes a condensing device 1, a compound heater 2, a condensate pump 3 and a water seal maintaining device 4. The condensing device 1 is used to cool the steam to form condensate. The compound heater 2 is used for the steam discharged from the steam turbine to exchange heat with the liquid discharged from the condensing device 1 to realize the waste heat utilization of the steam. The condensate pump 3 is used to pump the condensate discharged from the condensing device 1. The water seal maintaining device 4 is used to pump part of the condensate to a predetermined position of the condensing device 1, so as to form a water seal at the predetermined position of the condensing device 1.

[0031] As Figure 1 shown, the condensing device 1 includes a condenser 11 and a U-shaped tube 12 that are interconnected; the compound heater 2 has a steam circuit 21 and a water circuit 22. The steam circuit 21 exchanges heat with the water circuit 22 inside the compound heater 2. The steam inlet 211 of the steam circuit 21 is connected to the steam turbine, and the steam outlet 212 of the steam circuit 21 is connected to the U-shaped tube 12; the pump inlet 31 of the condensate pump 3 is connected to the bottom of the condenser 11, and the pump outlet 32 of the condensate pump 3 is connected to the water inlet end 221 of the water circuit 22; the water seal maintaining device 4 includes a water seal pipe 41 and an isolation valve 42. One end of the water seal pipe 41 is connected to the U-shaped tube 12, the other end of the U-shaped tube 12 is connected to the pump outlet 32, and the isolation valve 42 is arranged on the water seal pipe 41.

[0032] Understandably, the condenser 11 is used to cool down the steam entering it, so that the steam is cooled and condensed to form condensate, and the condensate will fall to the bottom of the condenser. The U-shaped tube 12 is integrally U-shaped. The U-shape can form a certain obstruction to the flow of steam, and at the same time is conducive to accumulating liquid to form a water seal.

[0033] The steam circuit 21 is for steam to flow, and the water circuit 22 is for liquid to flow. The steam inlet 211 allows the steam discharged from the steam turbine to enter. The steam flows along the steam circuit and is discharged via the steam outlet 212. The water circuit 22 has a water inlet end 221 and a water outlet end 222. The water inlet end 221 allows the liquid condensed by the condenser to enter. The liquid flows along the water circuit 22 and is discharged through the water outlet end 222. Among them, the steam circuit 21 and the water circuit 22 are not connected to each other. When the steam flows along the steam circuit 21, it will exchange heat with the liquid in the water circuit 22. In this way, the remaining heat in the steam can be correspondingly transferred to the liquid in the water circuit 22, achieving the purpose of waste heat utilization.

[0034] When the condensate pump 3 works, it sucks the condensate in the condenser 11 through the pump-in end 31. The condensate is pressurized and pumped by the condensate pump 3 and discharged through the pump-out end 32. The condensate pumped out by the condensate pump 3 is supplied to the water circuit 22. A small amount of condensate is guided into the corresponding U-shaped tube 12 through the water seal pipe 41, so that the U-shaped tube 12 can be cooled down. The isolation valve 42 is used to control the on-off of the water seal pipe 41.

[0035] The water seal pipe 41 is used to guide the liquid pumped out by the condensate pump 3 into the U-shaped tube 12, so that a water seal is formed in the U-shaped tube 12 to isolate the condenser 11 from the steam circuit 21.

[0036] Understandably, after the water seal is formed, the steam in the steam circuit 21 will be blocked between the U-shaped tube 12 and the steam circuit 21, so that the steam can stay in the double heater 2 for a long enough time, extending the heat exchange time between the steam and the condensate, and then improving the utilization rate of waste heat recovery and the working efficiency of the secondary circuit.

[0037] In addition, the water seal pipe 41 can be configured as a pipeline, and the isolation valve 42 can be configured as a valve that can switch the on-off of the pipeline commonly used in related technologies. Among them, the costs of both the water seal pipe 41 and the isolation valve 42 are very low and the installation is simple, and there is no need to modify the original secondary circuit system, avoiding excessive cost increase due to the improvement of waste heat utilization rate.

[0038] It should be noted that the double heater 2 is a prior art, and it usually has four interfaces. Two of the interfaces are connected to form a space or channel for steam to flow, that is, to form a steam circuit, and the other two interfaces are connected to form a space or channel for condensate to flow, that is, to form a water circuit.

[0039] Such as Figure 1As shown, in some embodiments of the secondary loop system 10 of a nuclear power plant, the secondary loop system 10 of the nuclear power plant further includes a pump-out pipe 5. One end of the pump-out pipe 5 communicates with the pump-out end 32, and the other end of the pump-out pipe 5 communicates with the water inlet end 221.

[0040] Understandably, the pump-out pipe 5 is used to guide the condensed water pumped by the condensate pump 3 into the water circuit 22 of the compound heater 2. The pump-out pipe 5 can be formed by a single pipe or formed by sequentially connecting multiple pipes.

[0041] As Figure 1 shown, in some embodiments of the secondary loop system 10 of a nuclear power plant, one end of the water seal pipe 41 communicates with the U-shaped pipe 12, and the other end of the water seal pipe 41 communicates with the pump-out pipe 5.

[0042] Understandably, directly connecting the U-shaped pipe 12 to the pump-out pipe 5 can avoid the cost increase caused by directly connecting the water seal pipe 41 to the condensate pump 3. Of course, for different application scenarios and when the layout of various components, devices, and mechanisms changes during actual operation, the connection position of the water seal pipe 41 can be flexibly set.

[0043] It should be noted that the diameter and length of the water seal pipe 41 are determined according to specific application requirements.

[0044] As Figure 1 shown, in some embodiments of the secondary loop system 10 of a nuclear power plant, the diameter of the water seal pipe 41 is smaller than the diameter of the pump-out pipe 5.

[0045] Understandably, the diameter of the water seal pipe 41 is configured to be smaller, aiming to avoid excessive loss of the flow pressure of the condensed water in the pump-out pipe 5 due to the too large diameter of the water seal pipe 41.

[0046] Specifically, the water seal pipe 41 is a capillary tube. Understandably, the capillary tube has the advantage of a small aperture. The condensed water ejected into the pump-out pipe 5 after being guided by the capillary tube will form a mist surface, and the mist surface can uniformly and effectively cool and dissipate heat inside the U-shaped pipe 12 through which it flows, enabling the steam to quickly condense into water when flowing through, and then forming the required water seal inside the U-shaped pipe 12.

[0047] Specifically, in some embodiments of the secondary loop system 10 of a nuclear power plant, the isolation valve 42 includes a gate valve, a globe valve, a ball valve, a butterfly valve, a cock valve, a diaphragm valve, or a needle valve.

[0048] Understandably, the isolation valve 42 can be configured as any one of the valve body types in this type of embodiment, and is specifically selected according to the actual working conditions and application requirements. Of course, other types of valve bodies in the prior art can also be used, as long as they can control the on-off of the water seal pipe 41.

[0049] Specifically, in some embodiments of the secondary loop system 10 of a nuclear power plant, the isolation valve 42 includes a manual valve, an electric valve, a pneumatic valve, a hydraulic valve, or a solenoid valve.

[0050] It can be understood that the isolation valve 42 can be configured to be controlled manually, electrically, pneumatically, or hydraulically. It can also be configured to be controlled in the form of electromagnetic actuation. The specific selection depends on the operation requirements in actual operation and whether remote control is needed, etc.

[0051] As Figure 1 shown, in some embodiments of the secondary loop system 10 of a nuclear power plant, the secondary loop system 10 of the nuclear power plant further includes a tee 6. The first port 61 of the tee 6 is connected to the U-shaped tube 12, the second port 62 of the tee 6 is connected to the bottom of the condenser 11, and the third port 63 of the tee 6 is connected to the side wall of the condenser 11.

[0052] It can be understood that the three ports, namely the first port 61, the second port 62, and the third port 63, are all interconnected, that is, any one port is connected to the other two ports.

[0053] It should be noted that during the actual working process, a certain amount of condensation will occur when the rising steam moves along the tee. The condensed water will flow towards the second port 62 under the action of gravity.

[0054] As Figure 1 shown, in some embodiments of the secondary loop system 10 of a nuclear power plant, the water seal maintaining device 4 includes a plurality of water seal pipes 41 and a plurality of isolation valves 42. Each water seal pipe 41 is connected to the U-shaped tube 12 and the pump outlet 32, and each isolation valve 42 is provided on each water seal pipe 41 in a one-to-one correspondence.

[0055] It can be understood that the setting of multiple water seal pipes 41 enables the present invention to work in a timely manner through the remaining water seal pipes 41 when a single water seal pipe 41 fails, improving the anti-risk ability of the system. At the same time, when the working power of the system is very large, multiple water seal pipes 41 can be opened simultaneously to increase the water supply amount of the water seal maintaining device 4 to the U-shaped tube 12 and ensure that the water seal can be formed.

[0056] Implementing the present invention has the following beneficial effects:

[0057] The present invention relates to a secondary loop system of a nuclear power plant. By introducing a condensation device and a compound heater into the system, efficient heat energy recovery is achieved, thereby improving the energy utilization efficiency of the entire system.

[0058] Meanwhile, only a water seal pipe and an isolation valve are needed to guide the liquid pumped out by the condensate pump to the U-shaped pipe, so that the U-shaped pipe can be cooled to form a water seal to isolate the condenser from the steam circuit, enabling the steam in the steam circuit to accumulate for a longer time, preventing the steam from passing through quickly and being directly discharged into the condenser, thereby making full use of the waste heat of the steam discharged from the steam turbine and effectively improving the waste heat utilization rate of the secondary circuit during high-power operation; further, the costs and installation of both the water seal pipe and the isolation valve are very simple, and there is no need to make major modifications to the original secondary circuit system, simplifying the convenience of improving the waste heat utilization rate and also avoiding excessive cost increase due to the improvement of waste heat utilization.

[0059] The solution of the present invention has been described in detail with reference to the accompanying drawings above. In the above embodiments, the descriptions of each embodiment have their own emphases. For the parts not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments. Those skilled in the art should also be aware that the actions and modules involved in the specification are not necessarily essential to the present invention. In addition, it can be understood that the steps in the method embodiments of the present invention can be adjusted, combined, and deleted according to actual needs, and the modules in the device embodiments of the present invention can be combined, divided, and deleted according to actual needs.

[0060] The various embodiments of the present invention have been described above. The above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations are obvious to those of ordinary skill in the art in the technical field without departing from the scope and spirit of the described embodiments. The choice of terms used herein is intended to best explain the principles of the embodiments, the practical application, or the improvement of the technology in the market, or to enable other ordinary skilled persons in the technical field to understand the embodiments disclosed herein.

Claims

1. A secondary circuit system of a nuclear power plant, characterized in that: include: A condensing device, the condensing device comprising a condenser and a U-shaped tube connected to each other; A compound heater, wherein the compound heater has a steam circuit and a water circuit, the steam circuit and the water circuit perform heat exchange in the compound heater, the steam inlet of the steam circuit is connected to the steam turbine, and the steam outlet of the steam circuit is connected to the U-shaped pipe; A condensate pump, wherein the pump inlet of the condensate pump is connected to the bottom of the condenser, and the pump outlet of the condensate pump is connected to the water inlet of the water circuit; and A water seal maintaining device, the water seal maintaining device comprising a water seal pipe and an isolation valve, one end of the water seal pipe is connected to the U-shaped pipe, the other end of the U-shaped pipe is connected to the pump outlet, and the isolation valve is arranged on the water seal pipe; The water seal pipe is used to guide the liquid pumped out by the condensate pump into the U-shaped tube, so that a water seal is formed in the U-shaped tube to isolate the condenser from the steam circuit.

2. The secondary circuit system of a nuclear power plant according to claim 1, characterized in that: The secondary loop system of the nuclear power plant further comprises a pump-out pipe, one end of which is connected to the pump-out end, and the other end of which is connected to the water inlet end.

3. The secondary circuit system of a nuclear power plant according to claim 2, characterized in that: One end of the water seal pipe is connected to the U-shaped pipe, and the other end of the water seal pipe is connected to the pump outlet pipe.

4. The secondary circuit system of a nuclear power plant according to claim 3, characterized in that: The diameter of the water seal pipe is smaller than the diameter of the pump outlet pipe; or The water seal tube is a capillary tube.

5. The secondary circuit system of a nuclear power plant according to any one of claims 1 to 4, characterized in that: The isolation valve includes a gate valve, a stop valve, a ball valve, a butterfly valve, a plug valve, a diaphragm valve or a needle valve.

6. The secondary circuit system of a nuclear power plant according to any one of claims 1 to 4, characterized in that: The isolation valve includes a manual valve, an electric valve, a pneumatic valve, a hydraulic valve or a solenoid valve.

7. The secondary circuit system of a nuclear power plant according to claim 1, characterized in that: The secondary loop system of the nuclear power plant further comprises a tee, a first port of the tee being connected to the U-shaped tube, a second port of the tee being connected to the bottom of the condenser, and a third port of the tee being connected to the side wall of the condenser.

8. The secondary circuit system of a nuclear power plant according to claim 1, characterized in that: The water seal maintaining device includes a plurality of water seal pipes and a plurality of isolation valves, each of the water seal pipes is connected to the U-shaped pipe and the pump outlet, and each of the isolation valves is arranged on each of the water seal pipes in a one-to-one correspondence.

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