WO2024055628A1 - 核反应堆用非能动余热排出系统及方法 - Google Patents

核反应堆用非能动余热排出系统及方法 Download PDF

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Publication number
WO2024055628A1
WO2024055628A1 PCT/CN2023/096007 CN2023096007W WO2024055628A1 WO 2024055628 A1 WO2024055628 A1 WO 2024055628A1 CN 2023096007 W CN2023096007 W CN 2023096007W WO 2024055628 A1 WO2024055628 A1 WO 2024055628A1
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WIPO (PCT)
Prior art keywords
heat
heat exchange
outlet
heat exchanger
stage
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PCT/CN2023/096007
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English (en)
French (fr)
Inventor
戚展飞
杨子江
王海涛
刘镝
吴燕华
李睿
胡楠
樊普
曹臻
李盛哲
曹克美
Original Assignee
上海核工程研究设计院股份有限公司
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Publication of WO2024055628A1 publication Critical patent/WO2024055628A1/zh

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    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21C—NUCLEAR REACTORS
    • G21C15/00—Cooling arrangements within the pressure vessel containing the core; Selection of specific coolants
    • G21C15/18—Emergency cooling arrangements; Removing shut-down heat
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E30/00—Energy generation of nuclear origin
    • Y02E30/30—Nuclear fission reactors

Definitions

  • the present invention relates to the field of nuclear reactor safety technology, and in particular to a passive residual heat removal system and method for a nuclear reactor.
  • the heat in the nuclear reactor core is exported to the steam turbine through the main heat exchanger such as the steam generator to generate electricity, or to the heating/steam supply system to generate heat energy or steam.
  • the main heat exchangers such as steam generators are unavailable, and a waste heat removal system must be configured to remove the waste heat from the core in time to prevent the accident from further deteriorating into a serious accident and causing the harm of a large amount of radioactive release.
  • Passive waste heat removal systems are used in some third-generation nuclear power plants.
  • the function of the passive waste heat removal system does not rely on external power, nor does it require support systems such as equipment cooling water. It relies on natural physical laws (density differences, natural circulation, heat conduction, etc.) to bring out Core heat. This makes the passive reserve
  • the failure probability of the heat removal system is much lower than that of the active waste heat removal system, which improves the safety of the nuclear reactor.
  • the existing passive waste heat removal system cannot reasonably consider different accidents. If the heat-carrying capacity of the waste heat removal system is too small, excessive heat will accumulate in the core, which may cause the core to melt; if the heat-carrying capacity is too large, the main system of the nuclear reactor will be overcooled and cause thermal shock, threatening the fatigue of key components. And the integrity of the pressure-bearing structure will also bring more serious accident consequences when the passive waste heat removal system is mistakenly started.
  • the present invention provides a non-kinetic energy waste heat removal system and method for nuclear reactors, which can meet the different requirements for the heat carrying capacity of the waste heat removal system under different accidents, avoid excessive or too small heat carrying capacity, and Reduce the adverse impact on the nuclear reactor system caused by the mis-starting of the passive waste heat removal system.
  • a first aspect of the invention provides a passive waste heat removal system for nuclear reactors, including:
  • a reactor system which includes a hot end and a cold end, the hot end outputs fluid outward, and the cold end inputs fluid inward;
  • a waste heat discharge system which includes a multi-stage heat exchanger, and two adjacent stages of heat exchangers are connected through an intermediate header;
  • the hot end is connected to the inlet of the first-stage heat exchanger through an inlet pipe;
  • the middle header is equipped with a side outlet, and the side outlet and the outlet of the last-stage heat exchanger are connected to the cold end through outlet pipes respectively, forming a multi-stage heat exchange loop.
  • Isolation valves are provided on the inlet pipe and each outlet pipe respectively.
  • the heat exchanger includes multiple groups of basic heat exchange modules.
  • the basic heat exchange module is composed of a heat exchange tube bundle and end tube plates arranged at both ends of the heat exchange tube bundle.
  • the heat exchange tube bundle includes a plurality of heat exchange tube bundles according to a predetermined The heat exchange tubes are arranged in sequence, and the end tube plates are provided with passages corresponding to the heat exchange tubes. hole.
  • multiple sets of basic heat exchange modules of the heat exchanger are connected in parallel and/or in series.
  • the inlet pipe and the heat exchanger are connected through an inlet header.
  • the inlet header is provided with a plurality of outlet pipes, and the multiple outlet pipes are respectively connected to multiple groups of basic heat exchange modules in parallel with the heat exchanger. connected.
  • the outlet pipe and the heat exchanger are connected through an outlet header.
  • the outlet header is provided with multiple inlet pipes, and the multiple inlet pipes are respectively connected to multiple groups of basic heat exchange modules in parallel with the heat exchanger. connected.
  • the heat exchange tubes of the heat exchange tube bundle are straight tubes or bent tubes.
  • the waste heat discharge system further includes a heat trap water tank, and the multi-stage heat exchanger is arranged in the heat trap water tank and arranged in stages from top to bottom.
  • the hot trap water tank is a water tank with a certain amount of water or a natural cooling water source, and the water surface height of the hot trap water tank is higher than that of the first-stage heat exchanger.
  • the reactor system and the waste heat removal system are arranged in the containment vessel, and a reflux collection tank is provided above the hot trap water tank.
  • the reflux collection tank is connected to the containment vessel and connected to the hot trap water tank through a reflux pipeline.
  • a second aspect of the invention provides a passive waste heat removal method for nuclear reactors, which includes the following steps:
  • a multi-stage heat exchanger is provided, and the adjacent two-stage heat exchangers are connected through an intermediate header respectively, and the intermediate header is provided with a side outlet;
  • An isolation valve is provided on the inlet pipe and each outlet pipe respectively;
  • the isolation valve on the inlet pipeline is in an open state, and the isolation valve on each outlet pipeline is in a closed state;
  • each outlet pipe When an accident occurs, the isolation valves on each outlet pipe are opened to form a connected fluid circulation loop.
  • the heat generated by the reactor system is carried by the fluid from the hot end through the inlet pipe through multi-stage heat exchange.
  • the heat exchanger is carried out, and the fluid that has transferred the heat is returned to the cold end of the reactor system through the outlet pipe, forming a cycle.
  • the nuclear reactor of the present invention uses a passive waste heat removal system and adopts a passive safety design concept. It does not rely on external power (such as power supply, steam source, etc.) and does not require support systems (such as equipment cooling water, power supply, etc.) in case of system failure. The probability is extremely low, which improves the safety of nuclear reactors; relying on natural physical laws (density differences, natural circulation, etc.), the driving fluid forms a natural circulation in the reactor system and passive waste heat removal system, bringing out the waste heat from the reactor core.
  • the passive waste heat removal system for nuclear reactors of the present invention can meet the different requirements for the heat carrying capacity of the waste heat removal system under different accidents. Through the design of the multi-stage heat exchanger, the heat carrying capacity is avoided from being too large or too small, and the heat carrying capacity is reduced. The adverse effects on the nuclear reactor system caused by the incorrect start-up of the passive waste heat removal system.
  • the invention can expand the heat exchanger of the passive waste heat system according to the needs of nuclear reactors of different power levels, adopts a modular design, and is flexible in installation; it can take into account the needs for core waste heat discharge after different accidents, and has strong scalability , flexible installation, suitable for nuclear reactors of different power levels, etc.
  • Figure 1 is a schematic structural diagram of a non-kinetic waste heat removal system for a reactor according to a specific embodiment of the present invention
  • FIG. 2 is a schematic diagram of a basic heat exchange module according to a specific embodiment of the present invention.
  • FIG. 3 is a schematic diagram of a basic heat exchange module according to another specific embodiment of the present invention.
  • Figure 4 is a schematic diagram of the heat exchange tube bundle arrangement according to a specific embodiment of the present invention.
  • FIG. 5 is a schematic diagram of the heat exchange tube bundle arrangement according to another specific embodiment of the present invention.
  • Figure 6 is a schematic diagram of the end tube plate of a specific embodiment of the present invention.
  • Figure 7 is a schematic diagram of the end tube plate of another specific embodiment of the present invention.
  • Figure 8 is a schematic diagram of the series connection of basic heat exchange modules according to a specific embodiment of the present invention.
  • Figure 9 is a schematic diagram of a parallel connection of basic heat exchange modules according to a specific embodiment of the present invention.
  • Figure 10 is a schematic diagram of a basic heat exchange module and an elbow-type basic heat exchange module connected in series according to a specific embodiment of the present invention
  • Figure 11 is a schematic diagram of a basic heat exchange module and an elbow-type basic heat exchange module connected in series and then in parallel according to a specific embodiment of the present invention
  • Figure 12 is a schematic diagram of the parallel arrangement of end tube plates of multiple groups of basic heat exchange modules according to a specific embodiment of the present invention.
  • Figure 13 is a schematic structural diagram of the heat exchanger inlet header of a specific embodiment of the present invention.
  • Figure 14 is a schematic diagram of the heat exchanger intermediate header according to a specific embodiment of the present invention.
  • Figure 15 is a schematic structural diagram of a non-kinetic waste heat removal system for a reactor according to another specific embodiment of the present invention.
  • the existing passive waste heat removal system cannot reasonably consider different accidents. If the heat-carrying capacity of the waste heat removal system is too small, excessive heat will accumulate in the core, which may cause the core to melt; if the heat-carrying capacity is too large, the main system of the nuclear reactor will be overcooled and cause thermal shock, threatening the fatigue of key components. And the integrity of the pressure-bearing structure will also bring more serious accident consequences when the passive waste heat removal system is mistakenly started.
  • the present invention provides a Passive waste heat removal system for nuclear reactors.
  • Figure 1 is a schematic structural diagram of a non-kinetic waste heat removal system for a reactor according to a specific embodiment of the present invention.
  • the passive waste heat removal system for nuclear reactors of the present invention includes: a reactor system 10 and a waste heat removal system 70 , both of which are installed in the containment 60 .
  • Reactor system 10 may be a nuclear reactor primary system or a nuclear reactor secondary system, such as a steam generator.
  • the main heat exchangers such as the steam generator are unavailable, and the heat in the reactor core cannot be exported through the main heat exchangers such as the steam generator.
  • the waste heat discharge system 70 can trigger the signal (such as high temperature at the reactor core outlet, low water level in the steam generator, low pressure in the regulator, etc.) start the waste heat removal system 70 to take out the heat in the reactor system 10 .
  • the signal Such as high temperature at the reactor core outlet, low water level in the steam generator, low pressure in the regulator, etc.
  • the reactor system 10 includes a hot end 1001 and a cold end 1002.
  • the hot end 1001 outputs fluid to the outside and the cold end 1002 inputs the fluid inward.
  • the fluid flows out from the hot end 1001 to the waste heat removal system 70 , and the heat-exchanged fluid flows back into the reactor system 10 from the cold end 1002 .
  • the hot end 1001 may be a primary side hot pipe section or a secondary side outlet of the nuclear reactor; the cold end 1002 may be a primary side cold pipe section or a secondary side inlet of the nuclear reactor.
  • the waste heat removal system 70 includes a multi-stage heat exchanger, and two adjacent stages of heat exchangers are connected through an intermediate header 23 respectively.
  • the embodiment shown in Figure 1 includes a two-stage heat exchanger (the first stage The heat exchanger 20 and the second-stage heat exchanger 30) will be described in detail.
  • the present invention is not limited to including two-stage heat exchangers, and the number of heat exchangers can be set according to actual usage requirements.
  • the hot end 1001 is connected to the inlet of the first-stage heat exchanger 20 through the inlet pipe 11; the intermediate header 23 is provided with a side outlet 150 (see Figure 14), and the side outlet 150 and the outlet of the last stage heat exchanger pass through the outlet pipe respectively.
  • the last stage heat exchanger in the embodiment in Figure 1 is the second stage heat exchanger 30, and the side outlet 150 of the intermediate header 23 is connected to the Cold end 1002, the outlet of the second stage heat exchanger 30 is connected to the cold end 1002 through the second outlet pipe 31.
  • Isolation valves are respectively provided on the inlet pipe 11 and each outlet pipe.
  • an inlet isolation valve 1 is provided on the inlet pipe 11
  • a first outlet isolation valve 2 is provided on the first outlet pipe 21
  • a second outlet isolation valve 2 is provided on the second pipe 31.
  • the inlet isolation valve 1 on the inlet pipe 11 is in an open state, and the first outlet isolation valve 2 and the second outlet isolation valve 3 are in a closed state.
  • the inlet isolation valve 1 is opened so that the fluid temperature in the inlet pipe 11 is greater than the first outlet pipe 21 and the second outlet pipe 31 before it is put into operation. This is conducive to strengthening the initial natural flow when the passive waste heat removal system 70 is put into use. cycle.
  • the inlet isolation valve 1 is opened, and the first outlet isolation valve 2 and the second outlet isolation valve 3 are closed, so that when the passive waste heat removal system 70 is put into operation, it only needs to ensure that the first outlet isolation valve 2 and the second outlet isolation valve 3 can be opened.
  • the inlet isolation valve 1 is opened, the first outlet isolation valve 2 and the second outlet isolation valve 3 are closed.
  • the fluid coming from the inlet isolation valve 1 is blocked in the mainstream direction, and there will be no large-scale fluid inflow.
  • the inlet isolation valve 1 and the first outlet isolation valve 2 and the second outlet isolation valve 3 are all closed, the heat exchange of the first-stage heat exchanger 20 and the second-stage heat exchanger 30 of the passive waste heat discharge system 70 will be The fluid in the tube bundle is in a water solid state.
  • the inlet isolation valve 1 is in an open state, since the first outlet isolation valve 2 and the second outlet isolation valve 3 are in a closed state, the fluid coming from the inlet isolation valve 1 is blocked in the mainstream direction, and there will be no Large-scale fluid inflow and a small amount of heat leakage from the fluid entering the heat exchange tube bundles of the first-stage heat exchanger 20 and the second-stage heat exchanger 30 through convection or secondary flow are acceptable.
  • the inlet isolation valve 1 of the passive waste heat removal system 70 is accidentally opened due to an operating error or system abnormality, although the fluid of the reactor system 10 will also enter the first-stage heat exchanger 20, The energy removed from the reactor system 10 will lead to unexpected temperature and pressure reduction of the reactor system 10 .
  • the heat exchange capacity of the first-stage heat exchanger 20 is relatively small, the adverse impact on the reactor system 10 is relatively small.
  • the passive waste heat removal system 70 can be triggered Signals (such as reactor core outlet high temperature, steam generator low water level, pressure regulator low pressure, etc.) start the passive waste heat removal system 70 and open the first outlet isolation valve 2 and the second outlet isolation valve in the middle of the passive waste heat removal system 70 3.
  • Signals such as reactor core outlet high temperature, steam generator low water level, pressure regulator low pressure, etc.
  • the heat generated in the reactor system 10 is carried by the fluid.
  • the fluid enters the heat exchangers of each stage (the first-stage heat exchanger 20 and the second-stage heat exchanger 30) in sequence through the inlet pipe 11, and the heat exchangers transfer the heat to Externally, the fluid returns to the reactor system 10 through the first outlet pipe 21 and the second outlet pipe 31 .
  • the fluid forms a natural circulation driven by the density difference between the fluid in the reactor system 10 and the fluid in the heat exchangers at each stage.
  • FIG. 2 is a schematic diagram of a basic heat exchange module according to a specific embodiment of the present invention.
  • the heat exchanger (the first-stage heat exchanger 20 and the second-stage heat exchanger 30) includes multiple groups of basic heat exchange modules 100.
  • the basic heat exchange modules 100 are composed of It consists of a heat exchange tube bundle and end tube plates 110 arranged at both ends of the heat exchange tube bundle.
  • FIG. 3 is a schematic diagram of a basic heat exchange module according to another specific embodiment of the present invention.
  • the heat exchange tubes of the heat exchange tube bundle are straight tubes or curved tubes.
  • the heat exchange tube bundle of the basic heat exchange module 100 in FIG2 is a straight tube heat exchange tube bundle 120, whose heat exchange tubes are straight tubes
  • the heat exchange tube bundle of the curved tube basic heat exchange module 200 shown in FIG3 is a curved tube heat exchange tube bundle 130, whose heat exchange tubes are curved tubes.
  • the first-stage heat exchanger 20 and the second-stage heat exchanger 30 may include multiple groups of basic heat exchange modules 100, or multiple groups of curved tube basic heat exchange modules 200, or a combination of basic heat exchange modules 100 and curved tube basic heat exchange modules 200.
  • the heat exchange tubes of the straight tube heat exchange tube bundle 120 and the bent tube heat exchange tube bundle 130 are composed of metal round tubes 101 with a certain thickness (see Figures 4 and 5) arranged in parallel.
  • the inner diameter of the round tubes is between 5mm and 25mm.
  • the wall thickness is between 0.5 and 5mm, or in compliance with national standards; the length of the metal round tube 101 can be customized according to needs; the material of the metal round tube 101 can be stainless steel, titanium alloy, aluminum alloy, etc.
  • the form of the metal round tube 101 is a straight tube for the basic heat exchange module 100, and the bent tube basic heat exchange module 200 is a round tube with a 90-degree bend in the middle of the tube; each basic heat exchange module only uses one form. Round tubes, that is, round tubes that are all straight tubes or round tubes that contain 90-degree bends.
  • the number of metal round tubes 101 constituting the straight tube heat exchange tube bundle 120 and the bent tube heat exchange tube bundle 130 can be customized as required.
  • Figure 4 is a schematic diagram of the arrangement of the heat exchange tube bundle in one specific embodiment of the present invention
  • Figure 5 is a schematic diagram of the arrangement of the heat exchange tube bundle in another specific embodiment of the present invention
  • Figure 6 is a schematic diagram of the end tube plate of one specific embodiment of the present invention
  • Figure 7 is a schematic diagram of the end tube plate of another specific embodiment of the present invention.
  • the straight tube heat exchange tube bundle 120 and the bent tube heat exchange tube bundle 130 include a plurality of heat exchange tubes arranged in a predetermined order, and the end tube plate 110 is provided with through holes corresponding to the heat exchange tubes. .
  • the metal round tubes 101 of the straight tube heat exchange tube bundle 120 and the bent tube heat exchange tube bundle 130 can be arranged in a fork row or in a straight row.
  • FIG. 4 shows a schematic diagram of the heat exchange tube bundles being arranged in sequence. The arrangement means that the center points of each metal round tube 101 form a straight line in both the X direction and the Y direction.
  • Figure 5 shows a schematic diagram of a cross row of heat exchange tube bundles. The cross row means that the metal round tubes 101 are in a straight line in the X direction, and the metal round tubes 101 are staggered in the Y direction.
  • the center distance between the metal round tubes 101 is between 1.1 and 2 times the outer diameter of the metal round tubes 101; in the length direction, the center distance between the metal round tubes 101 remains unchanged.
  • the two end tube plates 110 of the basic heat exchange module 100 are respectively connected to the two ends of the straight tube heat exchange tube bundle 120 by welding.
  • the two end tube plates 110 of the elbow-type basic heat exchange module 200 are respectively connected to the two ends of the elbow heat exchange tube bundle 130 by welding.
  • each end tube plate 110 has openings 103 corresponding to the number and size of the metal round tubes 101.
  • the two ends of each metal round tube 101 are connected to the two end tubes respectively.
  • the openings of the plates 110 are connected, and each end tube plate 110 is also provided with a flange bolt hole 102 for connecting the two end tube plates 110 through bolts.
  • the end tube plate 110 shown in Figure 6 can use a circular flange 105, which follows the national standard specifications to reduce manufacturing costs;
  • Figure 6 exemplarily shows the arrangement of the metal round tubes 101.
  • the arrangement of the metal round pipes 101 can also be a fork row, without any specific limitation.
  • the end tube plate 110 shown in Figure 7 can also use a hexagonal flange 104.
  • Figure 7 exemplarily shows the arrangement of the fork rows of the metal circular tube 101.
  • the hexagonal flange 104 is used, At this time, the arrangement of the metal round tubes 101 can also be in a sequence, and there is no specific limitation.
  • Figure 8 is a schematic diagram of the basic heat exchange modules connected in series according to a specific embodiment of the present invention
  • Figure 9 is a schematic diagram of the basic heat exchange modules connected in parallel according to a specific embodiment of the present invention
  • Figure 10 is a basic heat exchange module according to a specific embodiment of the present invention.
  • Figure 11 This is a schematic diagram of a basic heat exchange module and an elbow-type basic heat exchange module connected in series and then in parallel according to a specific embodiment of the present invention.
  • multiple sets of basic heat exchange modules of the heat exchanger are connected in parallel and/or in series.
  • the first-stage heat exchanger 20 and the second-stage heat exchanger 30 can adopt different combinations of basic heat exchange modules, including but not limited to multiple groups of straight-tube basic heat exchangers.
  • the thermal modules 100 are connected in series. Multiple groups of straight-tube basic heat exchange modules 100 are connected in parallel.
  • the straight-tube basic heat exchange module 100 and the bent-tube basic heat exchange module 200 are connected in series.
  • the straight-tube basic heat exchange module 100 and the bent tube are connected in series. After the basic heat exchange modules 200 are connected in series, multiple groups are connected in parallel, etc.
  • the series connection method of the basic heat exchange modules in Figure 8 is to connect the two basic heat exchange modules 100 into one body.
  • the fluid flows in from the inlet of the first basic heat exchange module 100 and enters the outlet of the second basic heat exchange module 100. Outflow (the direction indicated by the arrow in the figure).
  • the parallel connection method of basic heat exchange modules in Figure 9 is to place two basic heat exchange modules 100 side by side, divide the inlet pipeline into two pipelines to connect the two basic heat exchange modules 100 respectively, and the fluid enters the two basic heat exchange modules respectively. After the thermal module 100, they flow out from their respective outlets and then merge into one outlet pipeline (the direction indicated by the arrow in the figure).
  • the basic heat exchange module 100 and the elbow-type basic heat exchange module 200 are connected in series.
  • the fluid flows in from the inlet of the elbow-type basic heat exchange module 200 and flows out from the outlet after entering the basic heat exchange module 100 (indicated by the arrow in the figure) direction), of course, depending on the layout of the pipeline, the fluid can also flow in from the inlet of the basic heat exchange module 100, enter the elbow type basic heat exchange module 200, and then flow out from the outlet.
  • Figure 11 shows that after the basic heat exchange module 100 and the elbow-type basic heat exchange module 200 in Figure 10 are connected in series as one, then two sets of series-connected basic heat exchange modules 100 and the elbow-type basic heat exchange module are 200 in parallel. After the fluid enters the two sets of series-connected basic heat exchange modules 100 and the elbow-type basic heat exchange module 200, it flows out from their respective outlets and then merges into an outlet pipeline (the direction indicated by the arrow in the figure).
  • Figure 12 is a schematic diagram of the parallel arrangement of end tube plates of multiple groups of basic heat exchange modules according to a specific embodiment of the present invention.
  • Figure 12 includes 7 sets of hexagonal flanges 104, one of which is located at the center, and the other six hexagonal flanges 104 are respectively close to the six sides of the central hexagonal flange 104, so that The parallel arrangement can make the straight tube heat exchange tube bundle 120 or the bent tube heat exchange tube bundle 130 form a closer arrangement, fully reducing the space required for installation.
  • the basic heat exchange module 100 and the elbow-type basic heat exchange module 200 can be modularly prefabricated in a manufacturing factory and then transported to the nuclear reactor site for assembly, which facilitates construction and installation.
  • Figure 13 is a schematic structural diagram of the heat exchanger inlet header according to a specific embodiment of the present invention.
  • the inlet pipe 11 and the heat exchanger are connected through the inlet header 12.
  • the inlet header 12 is provided with a plurality of outlet pipes 124, and the multiple outlet pipes 124 are respectively connected with Multiple groups of basic heat exchange modules 100 connected in parallel of the heat exchanger are connected.
  • the inlet header 12 is composed of an inlet ellipsoidal head 121, an outlet ellipsoidal head 123, a cylindrical body 122, an inlet 125 and an outlet pipe 124.
  • the diameter of the cylindrical body 122 is not smaller than the diameter of the inlet pipe 11 .
  • the inlet ellipsoid head 121 is connected to the inlet pipe 11 through the inlet 125; the outlet ellipsoid head 123 is connected to the inlet of the first-stage heat exchanger 20 through the outlet pipe 124.
  • the first-stage heat exchanger 20 When the first-stage heat exchanger 20 is composed of multiple groups of basic heat exchange modules 100 connected in parallel, a plurality of outlet pipes 124 symmetrical along its central axis can be connected to the outlet ellipsoid head 123.
  • the outlet pipes 124 are connected to the parallel basic heat exchange modules 100.
  • the heat exchange modules 100 correspond one to one.
  • the second outlet pipe 31 is connected to the second stage heat exchanger 30 are connected through a second outlet header 32, which is provided with a plurality of inlet pipes, and the plurality of inlet pipes are respectively connected to multiple groups of basic heat exchange modules 100 connected in parallel of the second-stage heat exchanger 30.
  • the first outlet pipe 21 and the intermediate header 23 are connected through the first outlet header 22 , and the inlet pipe of the first outlet header 22 is connected with the side outlet 150 of the intermediate header 23 .
  • the inlet header 12 , the first outlet header 22 , and the second outlet header 32 have the same structure, and the diameter of the cylindrical barrel 122 is not smaller than the inlet pipe 11 , the first outlet pipe 21 , or the second outlet pipe 31 diameter of.
  • the inlet pipes of the first outlet header 22 and the second outlet header 32 are the outlet pipes 124 of the inlet header 12 .
  • Figure 14 is a schematic diagram of the heat exchanger intermediate header according to a specific embodiment of the present invention.
  • the intermediate header 23 includes a main connecting pipe 140 and a side outlet 150.
  • the side outlet 150 is provided on the side of the main connecting pipe 140.
  • End tube plates 110 are provided above and below the main connecting pipe 140, and are connected with the first
  • the end tube plates 110 of the basic heat exchange module 100 of the first-stage heat exchanger 20 and the second-stage heat exchanger 30 are matched and connected and fixed with bolts through flange bolt holes 102 .
  • the pipe flange 111 is installed on the side outlet 150;
  • the main connecting pipe 140 is in the form of a straight circular pipe, and its inner diameter is not less than the diameter of the largest circumscribed circle of the tube bundle opening area of the end tube plate 110 to ensure that it is connected to the end tube plate 110 All the fluids in the tube bundle can enter the main connecting pipe 140; the length of the main connecting pipe 140 is no longer than the length of a set of basic heat exchange modules 100; both ends of the main connecting pipe 140 are connected to the two end tube plates 110 respectively.
  • the side outlet 150 is in the form of a round pipe, and the inner diameter of the pipe is no larger than the main connecting pipe 140; the side outlet 150 can be composed of multiple elbows and straight pipe sections, and its length and direction are based on installation needs, so that the intermediate header 23 can be connected with the first outlet.
  • the inlet of the header 22 is connected; one end of the side outlet 150 is connected to the side of the middle part of the main connecting pipe 140, and the other end is connected to the pipe flange 111.
  • the waste heat discharge system 70 also includes a heat trap water tank 50.
  • Each heat exchanger is disposed in the heat trap water tank 50, and is arranged in sequence from top to bottom. Stage arrangement, for example, in the embodiment in FIG. 1 , the first stage heat exchanger 20 is located above the second stage heat exchanger 30 .
  • the heat trap water tank 50 is a water tank with a certain amount of water, or it can be a natural cooling water source such as a river, a lake, or the sea.
  • the water surface height of the heat trap water tank 50 is higher than that of the first-stage heat sink. exchanger 20 and second-stage heat exchanger 30.
  • the reactor system 10 and the waste heat removal system 70 are arranged in the containment 60, and a backflow collection tank 51 is provided above the heat trap water tank 50.
  • the backflow collection tank 50 is connected to the containment 60 and is connected to the containment vessel 60 through a backflow pipeline.
  • 52 is connected to the hot trap water tank 50 .
  • the hot trap water tank 50 is used together with the containment vessel 60 , the return flow collection tank 51 , and the return flow pipeline 52 ; one end of the return flow pipeline 52 is connected to the bottom of the return flow collection tank 51 , and the other end is located above the hot trap water tank 50 .
  • the first-stage heat exchanger 20, the intermediate header 23, and the second-stage heat exchanger 30 are fixedly installed in the heat trap water tank 50; the elevation of the center positions of the first-stage heat exchanger 20 and the second-stage heat exchanger 30 are higher than the central elevation of the hot end 1001 of the reactor system 10 .
  • the hot end 1001 of the reactor system 10 refers to the reactor core; when the reactor system 10 is a nuclear reactor secondary side system, the hot end 1001 of the reactor system 10 refers to one or two The heat exchange tube bundle of the secondary heat exchanger.
  • the heat generated in the reactor system 10 is carried by the fluid.
  • the fluid enters the heat exchangers of each stage (the first-stage heat exchanger 20 and the second-stage heat exchanger 30) in sequence through the inlet pipe 11, and the heat exchangers transfer the heat to
  • the fluid from the hot trap water tank 50 returns to the reactor system 10 through the first outlet pipe 21 and the second outlet pipe 31 .
  • the fluid forms a natural circulation driven by the density difference between the fluid in the reactor system 10 and the fluid in the heat exchangers at each stage.
  • the water in the hot trap water tank 50 is continuously heated until it is saturated and evaporates.
  • the steam is cooled by the inner wall of the containment vessel 60 and condensed into water, which is collected by the reflux collection tank 51 and returned to the hot trap water tank 50 through the reflux pipeline 52 to achieve long-term circulation. .
  • the heat on the inner wall of the containment vessel 60 is brought to the outside through heat conduction. wall, and finally discharged into the atmosphere through convection heat transfer and other methods.
  • the system's heat generation capacity finally matched the core decay heat, and more serious accident conditions were no longer possible in the power plant.
  • the number of outlet isolation valves opened can be increased according to the trigger signal (such as low pressure of the pressure regulator), which allows the exhaust from the reactor to
  • the fluid of system 10 enters the multi-stage heat exchanger and transfers heat to the heat sink tank 50 . This results in a lower enthalpy of the fluid returning to the reactor system 10 .
  • the fluid also forms a natural circulation driven by density differences.
  • Figure 15 is a schematic structural diagram of a non-kinetic waste heat removal system for a reactor according to another specific embodiment of the present invention.
  • a third-stage heat exchanger 40 can be provided, and a second intermediate header 33 is provided between the second-stage heat exchanger 30 and the third heat exchanger 40, specifically, the second-stage heat exchanger
  • the outlet of 30 is connected to the inlet of the second intermediate header 33; the outlet of the second intermediate header 33 is connected to the inlet of the third-stage heat exchanger 40; the outlet of the second intermediate header 33 is connected to the inlet of the second outlet header 32 connected; the outlet of the third-stage heat exchanger 40 is connected with the inlet of the third outlet header 42.
  • the present invention is not limited to setting up two-stage or three-stage heat exchangers, and different numbers of heat exchangers can be set up according to actual needs.
  • the present invention also provides a passive waste heat removal method for nuclear reactors, which includes the following steps.
  • Step S1 set up a multi-stage heat exchanger, and connect the adjacent two-stage heat exchangers through an intermediate header, and the intermediate header is provided with a side outlet;
  • Step S2 Connect the hot end of the reactor system to the inlet of the first-stage heat exchanger through the inlet pipe. connect;
  • Step S3 connect the side outlet and the last stage heat exchanger outlet to the cold end of the reactor system through outlet pipes respectively to form a multi-stage heat exchange loop;
  • Step S4 Set isolation valves on the inlet pipe and each outlet pipe respectively;
  • Step S5 When the reactor system is operating normally, the isolation valve on the inlet pipe is in an open state, and the isolation valve on each outlet pipe is in a closed state;
  • Step S6 When an accident occurs, the isolation valves on each outlet pipe are opened to form a connected fluid circulation loop.
  • the heat generated by the reactor system is carried by the fluid from the hot end through the inlet pipe through multiple The heat exchanger performs heat exchange, and the fluid that has transferred the heat is returned to the cold end of the reactor system through the outlet pipe, forming a cycle.
  • the number of heat exchanger stages to be used is selected according to different accidents or different stages of the accident.

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Abstract

本发明提供一种核反应堆用非能动余热排出系统和方法，该系统包括：反应堆系统，其包括热端和冷端，热端向外输出流体，冷端向内输入流体；余热排出系统，其包括多级热交换器，相邻两级热交换器之间分别通过中间联箱连接；其中，热端通过入口管道与第一级热交换器入口连接；中间联箱设有侧出口，侧出口和最后一级热交换器出口分别通过出口管道连接至冷端，形成多级换热回路；入口管道和各出口管道上分别设有隔离阀。本发明能够满足在不同事故下，对余热排出系统的带热能力的不同需求，通过多级热交换器的设计，避免带热量过大或过小，并减小非能动余热排出系统误启动对核反应堆系统造成的不利影响。

Description

核反应堆用非能动余热排出系统及方法
相关申请的交叉引用
本申请要求享有于2022年09月14日提交的名称为“一种核反应堆用非能动余热排出系统及方法”的中国专利申请202211115574.4的优先权，该申请的全部内容通过引用并入本文中。
技术领域
本发明涉及核反应堆安全技术领域，具体涉及一种核反应堆用非能动余热排出系统及方法。
背景技术
在正常运行条件下，核反应堆堆芯热量通过蒸汽发生器等主热交换器导出至汽轮机，进而产生电力，或导出至供热/供汽系统产生热能或蒸汽。而在核反应堆发生事故后，蒸汽发生器等主热交换器不可用，必须配置余热排出系统，及时带出堆芯的余热，以防事故进一步恶化为严重事故，造成大量放射性释放的危害。
传统二代核电站一般采用能动的余热排出系统带出堆芯余热，而能动系统依赖于外部动力，并需要配置设备冷却水等支持系统，一旦外部动力或支持系统丧失，能动的余热排出系统将无法执行其功能，进而导致堆芯余热无法被带出，威胁核反应堆安全。
在一些三代核电站中采用非能动余热排出系统，非能动余热排出系统的功能执行不依靠外部动力，也无需设备冷却水等支持系统，依靠自然物理规律(密度差、自然循环、热传导等)带出堆芯热量。这使得非能动余 热排出系统的失效概率远低于能动的余热排出系统，提高了核反应堆的安全性。
发明人发现，在不同事故下(例如失水事故(LOCA事故)和非LOCA事故)，非能动余热排出系统的带热能力可能有不同的需求。现有的非能动余热排出系统无法对不同事故进行合理的兼顾。余热排出系统的带热能力过小，会使得堆芯热量过多的积聚，可能造成堆芯熔化；带热能力过大，则会使得核反应堆主系统过冷，并造成热冲击，威胁关键部件疲劳和承压结构完整性，还会在非能动余热排出系统的误启动时，带来更严重事故后果。
发明内容
针对现有技术存在的问题，本发明提供一种核反应堆用非动能余热排出系统及方法，能够满足不同事故下对余热排出系统的带热能力的不同需求，避免带热量过大或过小，并减小非能动余热排出系统误启动对核反应堆系统的造成的不利影响。
本发明第一方面提供一种核反应堆用非能动余热排出系统，包括：
反应堆系统，其包括热端和冷端，热端向外输出流体，冷端向内输入流体；
余热排出系统，其包括多级热交换器，相邻两级热交换器之间分别通过中间联箱连接；
其中，热端通过入口管道与第一级热交换器入口连接；中间联箱设有侧出口，侧出口和最后一级热交换器出口分别通过出口管道连接至冷端，形成多级换热回路；入口管道和各出口管道上分别设有隔离阀。
在本发明的一些实施方式中，热交换器包括多组基础换热模块，基础换热模块由换热管束和设置在换热管束两端的端部管板组成，换热管束包括多个按照预定顺序排列的换热管，端部管板上设有与换热管对应的通 孔。
在本发明的一些实施方式中，热交换器的多组基础换热模块并联和/或串联连接。
在本发明的一些实施方式中，入口管道与热交换器通过入口联箱连接，入口联箱设有多个出口管，多个出口管分别与热交换器的并联连接的多组基础换热模块相连接。
在本发明的一些实施方式中，出口管道与热交换器通过出口联箱连接，出口联箱设有多个入口管，多个入口管分别与热交换器的并联连接的多组基础换热模块相连接。
在本发明的一些实施方式中，换热管束的换热管为直管或弯管。
在本发明的一些实施方式中，余热排出系统还包括热阱水箱，多级热交换器设置在热阱水箱中，并且从上至下依次逐级设置。
在本发明的一些实施方式中，热阱水箱为一定装水量的水箱或天然冷却水源，热阱水箱的水面高度高于第一级热交换器。
在本发明的一些实施方式中，反应堆系统和余热排出系统设置在安全壳内，热阱水箱上方设有回流收集槽，回流收集槽与安全壳相连，并通过回流管线与热阱水箱连接。
本发明第二方面提供一种核反应堆用非能动余热排出方法，包括以下步骤：
设置多级热交换器，将相邻两级热交换器之间分别通过中间联箱连接，所述中间联箱设有侧出口；
将反应堆系统的热端通过入口管道与第一级热交换器入口连接；
将所述侧出口和最后一级热交换器出口分别通过出口管道连接至和反应堆系统的冷端，形成多级换热回路；
在所述入口管道和所述各出口管道上分别设置隔离阀；
在反应堆系统正常运行时，使所述入口管道上的隔离阀处于打开状态，使各出口管道上的隔离阀处于关闭状态；
当发生事故情况后，打开各所述出口管道上的隔离阀，形成连通的流体的循环回路，由反应堆系统产生的热量由流体携带，从所述热端通过所述入口管道通过多级热交换器进行换热，传递完热量的流体再通过所述出口管道返回至所述反应堆系统的冷端，形成循环。
本发明技术方案具有以下有益效果：
本发明的核反应堆用非能动余热排出系统，采用非能动的安全设计理念，不依赖外部动力(如电源、汽源等)，也无需支持系统，(如：设备冷却水、电源等)，系统失效概率极低，提高了核反应堆的安全性；依靠自然物理规律(密度差、自然循环等)，驱动流体在反应堆系统和非能动余热排出系统内形成自然循环，带出反应堆堆芯余热。
本发明的核反应堆用非能动余热排出系统能够满足在不同事故下，对余热排出系统的带热能力的不同需求，通过多级热交换器的设计，避免带热量过大或过小，并减小非能动余热排出系统误启动对核反应堆系统造成的不利影响。
本发明可以根据不同功率等级的核反应堆的需求，对非能动余热系统的热交换器进行扩展，采用模块化设计，安装灵活；可以兼顾不同事故后对堆芯余热排出的需求，具有可扩展性强、安装灵活、适用于不同功率等级的核反应堆等特点。
应当理解的是，以上的一般描述和后文的细节描述仅是示例性的，并不能限制本申请。
附图说明
为了更清楚地说明本申请实施例的技术方案，下面将对本申请实施例中所需使用的附图作简单地介绍，显而易见，以下描述的附图仅仅是本申请的具体实施例，本领域技术人员在不付出创造性劳动的前提下，可以根据以下附图获得其他实施例。
图1是本发明一个具体实施例的反应堆用非动能余热排出系统的结构示意图；
图2为本发明一个具体实施例的基础换热模块示意图；
图3为本发明另一个具体实施例的基础换热模块示意图；
图4为本发明一个具体实施例的换热管束排列示意图；
图5为本发明另一个具体实施例的换热管束排列示意图；
图6为本发明一个具体实施例的端部管板示意图；
图7为本发明另一个具体实施例的端部管板示意图；
图8为本发明一个具体实施例的基础换热模块串联的示意图；
图9为本发明一个具体实施例的基础换热模块并联的示意图；
图10为本发明一个具体实施例的基础换热模块与弯管式基础换热模块串联的示意图；
图11为本发明一个具体实施例的基础换热模块与弯管式基础换热模块串联后再并联的示意图；
图12是本发明一个具体实施例的多组基础换热模块端部管板并联排列示意图；
图13是本发明一个具体实施例的热交换器入口联箱结构示意图；
图14是本发明一个具体实施例的热交换器中间联箱示意图；
图15是本发明另一个具体实施例的反应堆用非动能余热排出系统的结构示意图。
附图标记：
10-反应堆系统；
1001-热端；
1002-冷端；
70-余热排出系统；
1-入口隔离阀；
2-第一出口隔离阀；
3-第二出口隔离阀；
11-入口管道；
12-入口联箱；
121-入口椭球封头；
123-出口椭球封头；
122-圆柱筒体；
125-入口；
124-出口管；
21-第一出口管道；
22-第一出口联箱；
23-中间联箱；
140-主连接管；
150-侧出口；
111-管法兰；
31-第二出口管道；
32-第二出口联箱；
33-第二中间联箱；
20-第一级热交换器；
100-基础换热模块；
110-端部管板；
101-金属圆管；
102-法兰螺栓孔；
104-六边形法兰；
105-圆形法兰；
120-直管换热管束；
200-弯管式基础换热模块；
130-弯管换热管束；
30-第二级热交换器；
40-第三级热交换器；
42-第三出口联箱；
50-热阱水箱；
51-回流收集槽；
52-回流管线；
60-安全壳。
此处的附图被并入说明书中并构成本说明书的一部分，示出了符合本申请的实施例，并与说明书一起用于解释本申请的原理。
具体实施方式
为了更好的理解本申请的技术方案，下面结合附图对本申请实施例进行详细描述。
应当明确，所描述的实施例仅仅是本申请一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域普通技术人员在没有作出创造性劳动前提下所获得的所有其它实施例，都属于本申请保护的范围。
现有的非能动余热排出系统无法对不同事故进行合理的兼顾。余热排出系统的带热能力过小，会使得堆芯热量过多的积聚，可能造成堆芯熔化；带热能力过大，则会使得核反应堆主系统过冷，并造成热冲击，威胁关键部件疲劳和承压结构完整性，还会在非能动余热排出系统的误启动时，带来更严重事故后果。
为了满足不同事故下对余热排出系统的带热能力的不同需求，避免带热量过大或过小，并减小非能动余热排出系统误启动对核反应堆系统的造成的不利影响，本发明提供一种核反应堆用非能动余热排出系统。
图1是本发明一个具体实施例的反应堆用非动能余热排出系统的结构示意图。
如图1所示，本发明的核反应堆用非能动余热排出系统，包括：反应堆系统10和余热排出系统70，二者均安装在安全壳60内。反应堆系统10可以为核反应堆一次侧系统或核反应堆二次侧系统，例如蒸汽发生器。当事故情况下，蒸汽发生器等主换热器不可用，堆芯的热量无法通过蒸汽发生器等主换热器导出，为防止事故进一步恶化为严重事故，可通过余热排出系统70触发信号(如堆芯出口高温、蒸汽发生器低水位、稳压器低压力等)启动余热排出系统70，带出反应堆系统10内的热量。
反应堆系统10包括热端1001和冷端1002，热端1001向外输出流体，冷端1002向内输入流体。本发明中，流体从热端1001中流出至余热排出系统70，经换热的流体再从冷端1002回流至反应堆系统10内。热端1001可以是核反应堆一次侧热管段或二次侧出口等；冷端1002可以是核反应堆一次侧冷管段或二次侧入口等。
余热排出系统70包括多级热交换器，相邻两级热交换器之间分别通过中间联箱23连接。图1所示的实施例中以包括两级热交换器(第一级 热交换器20和第二级热交换器30)进行详细说明，当然，本发明并不仅仅限于包括两级热交换器，热交换器的数量可以根据实际使用需求设置。
热端1001通过入口管道11与第一级热交换器20的入口连接；中间联箱23设有侧出口150(见图14)，侧出口150和最后一级热交换器的出口分别通过出口管道连接至冷端1002，形成多级换热回路，图1中实施例的最后一级热交换器即第二级热交换器30，中间联箱23的侧出口150通过第一出口管道21连接至冷端1002，第二级热交换器30的出口通过第二出口管道31连接至冷端1002。
入口管道11和各出口管道上分别设有隔离阀，图1中，入口管道11上设置入口隔离阀1，第一出口管道21上设置第一出口隔离阀2，第二管道上31设置第二出口隔离阀3。
在核反应堆正常运行时，入口管道11上的入口隔离阀1处于打开状态，第一出口隔离阀2和第二出口隔离阀3处于关闭状态。入口隔离阀1打开使得在其投运前，入口管道11内的流体温度就大于第一出口管道21和第二出口管道31，这样有利于非能动余热排出系统70投入使用时，强化初始的自然循环。入口隔离阀1打开、第一出口隔离阀2和第二出口隔离阀3关闭，使得非能动余热排出系统70投运时，只需要确保第一出口隔离阀2和第二出口隔离阀3能够打开就能运行，而不需要所有隔离阀都打开，消除了入口隔离阀1失效导致的非能动余热排出系统70投运失败的风险。入口隔离阀1打开、第一出口隔离阀2和第二出口隔离阀3关闭，从入口隔离阀1而来的流体在主流方向上是隔断的，不会有大规模流体流入。但如果入口隔离阀1以及第一出口隔离阀2和第二出口隔离阀3若都关闭，使得非能动余热排出系统70的第一级热交换器20和第二级热交换器30的换热管束内的流体处于水实体密闭状态。由于导热漏热，非能动余热排出 系统70的第一级热交换器20和第二级热交换器30的换热管束内的流体在水实体状态下受热膨胀后，可能由于导热漏热威胁隔离阀和第一级热交换器20和第二级热交换器30的换热管束组成的结构边界，例如导致隔离阀泄漏。因此，虽然入口隔离阀1处于打开状态，但是由于第一出口隔离阀2和第二出口隔离阀3为关闭状态，从入口隔离阀1而来的流体在主流方向上是隔断的，不会有大规模流体流入，少量通过对流或二次流进入第一级热交换器20和第二级热交换器30的换热管束的流体的漏热是可以接受的。
另一方面，如果在核反应堆正常运行时，非能动余热排出系统70的入口隔离阀1因为操作失误或者系统异常导致误打开，虽然也会使得反应堆系统10的流体进入第一级热交换器20，移出反应堆系统10的能量，进而导致反应堆系统10意外的降温降压，但是由于第一级热交换器20的换热能力相对较小，对于反应堆系统10的不利影响相对较小。
当事故情况下，蒸汽发生器等主换热器不可用，堆芯的热量无法通过蒸汽发生器等主换热器导出，为防止事故进一步恶化为严重事故，可通过非能动余热排出系统70触发信号(如堆芯出口高温、蒸汽发生器低水位、稳压器低压力等)启动非能动余热排出系统70，打开非能动余热排出系统70中间的第一出口隔离阀2和第二出口隔离阀3，使得反应堆系统10和每级热交换器之间形成连通的流体的循环回路。
在反应堆系统10中产生的热量由流体携带，流体通过入口管道11依次进入各级热交换器(第一级热交换器20和第二级热交换器30)，由热交换器将热量传递给外部，再通过第一出口管道21和第二出口管道31，流体返回反应堆系统10。整个过程中，流体在反应堆系统10内流体和各级热交换器内流体密度差的驱动下形成自然循环。
图2为本发明一个具体实施例的基础换热模块示意图。
如图2所示，在本发明的一些实施方式中，热交换器(第一级热交换器20和第二级热交换器30)包括多组基础换热模块100，基础换热模块100由换热管束和设置在换热管束两端的端部管板110组成。
图3为本发明另一个具体实施例的基础换热模块示意图。
在一些具体实施方式中，换热管束的换热管为直管或弯管。图2中的基础换热模块100换热管束为直管换热管束120，其换热管为直管，图3中所示的弯管式基础换热模块200换热管束为弯管换热管束130，其换热管为弯管。第一级热交换器20和第二级热交换器30中可以包括多组基础换热模块100，也可以包括多组弯管式基础换热模块200，或者是基础换热模块100和弯管式基础换热模块200的组合。
直管换热管束120和弯管换热管束130的换热管均为具有一定厚度的金属圆管101(见图4、图5)平行排列组成，圆管内径在5mm～25mm之间，管壁厚度在0.5～5mm之间，或采用符合国家标准的规格；金属圆管101的长度可以根据需要定制；金属圆管101的材质可以是不锈钢、钛合金、铝合金等。金属圆管101的形式，对于基础换热模块100是直管，对于弯管式基础换热模块200是管中部有90度弯折的圆管；每种基础换热模块只采用一种形式的圆管，即均为直管的圆管或均为含90度弯管的圆管。组成直管换热管束120和弯管换热管束130的金属圆管101的数量根据需求可以任意定制。
图4为本发明一个具体实施例的换热管束排列示意图；图5为本发明另一个具体实施例的换热管束排列示意图；图6为本发明一个具体实施例的端部管板示意图；图7为本发明另一个具体实施例的端部管板示意图。
如图4至图7所示，直管换热管束120和弯管换热管束130包括多个按照预定顺序排列的换热管，端部管板110上设有与换热管对应的通孔。
直管换热管束120和弯管换热管束130的金属圆管101的排列方式可以是叉排，也可以是顺排。图4示出了换热管束顺排的示意图，顺排是指各金属圆管101的中心点在X方向和Y方向上均形成一条直线。图5示出了换热管束叉排的示意图，叉排是指各金属圆管101在X方向成一条直线，在Y方向上各金属圆管101交错排列。
金属圆管101之间的中心距在1.1～2倍金属圆管101的外径之间；在长度方向上，金属圆管101之间的中心距保持不变。
基础换热模块100的两块端部管板110分别与直管换热管束120的两端通过焊接的方式相连。弯管式基础换热模块200的两块端部管板110分别与弯管换热管束130的两端通过焊接的方式相连。
如图6和图7所示，每块端部管板110开有与金属圆管101的数量以及大小对应的开孔103，每根金属圆管101的两端与分别与两块端部管板110的开孔相连，每块端部管板110上还设有法兰螺栓孔102，用于通过螺栓连接两片端部管板110。
图6示出的端部管板110可以采用圆形法兰105，遵循国家标准规格以降低制造成本；图6中示例性的示出了金属圆管101的顺排的排列方式，当然，在采用圆形法兰105时，金属圆管101的排列方式也可以是叉排，并不做具体限制。图7示出的端部管板110也可以采用六边形法兰104，图7中示例性的示出了金属圆管101的叉排的排列方式，当然，在采用六边形法兰104时，金属圆管101的排列方式也可以是顺排，并不做具体限制。
图8为本发明一个具体实施例的基础换热模块串联的示意图；图9为本发明一个具体实施例的基础换热模块并联的示意图；图10为本发明一个具体实施例的基础换热模块与弯管式基础换热模块串联的示意图；图11 为本发明一个具体实施例的基础换热模块与弯管式基础换热模块串联后再并联的示意图。
如图8至图11所示，在本发明的一些实施方式中，热交换器的多组基础换热模块并联和/或串联连接。
根据安装便利性、维修维护便利性的需要，第一级热交换器20和第二级热交换器30可以采取不同组合方式的基础换热模块，包括但不限于将多组直管式基础换热模块100串联，将多组直管式基础换热模块100并联，将直管式基础换热模块100与弯管式基础换热模块200串联，将直管式基础换热模块100与弯管式基础换热模块200进行串联后再进行多组并联等。
图8中基础换热模块串联的连接方式是将两个基础换热模块100连接为一体，流体从第一个基础换热模块100的入口流入，进入第二个基础换热模块100后从出口流出(图中箭头指示的方向)。
图9中基础换热模块并联的连接方式是将两个基础换热模块100并列放置，将入口管路分为两个管路分别连接两个基础换热模块100，流体分别进入两个基础换热模块100后，分别从各自出口流出后在汇流至一个出口管路中(图中箭头指示的方向)。
图10中基础换热模块100与弯管式基础换热模块200串联为一体，流体从弯管式基础换热模块200的入口流入，进入基础换热模块100后从出口流出(图中箭头指示的方向)，当然，根据管路的布置方式，流体也可以从基础换热模块100的入口流入，进入弯管式基础换热模块200后从出口流出。
图11中示出了图10基础换热模块100与弯管式基础换热模块200串联为一体后，再将两组串联的基础换热模块100与弯管式基础换热模块 200并联。流体分别进入两组串联的基础换热模块100与弯管式基础换热模块200后，分别从各自出口流出后在汇流至一个出口管路中(图中箭头指示的方向)。
图12是本发明一个具体实施例的多组基础换热模块端部管板并联排列示意图。
如图12所示，多组基础换热模块100或弯管式基础换热模块200并联后，多组端部管板110并联排列在一起。图12中包括7组六边形法兰104，其中一个六边形法兰104位于中心位置，其它六个六边形法兰104分别紧靠中心的六边形法兰104的六条边，这样的并联排列方式，可以使得直管换热管束120或弯管换热管束130形成更加紧密的排列，充分减小安装所需空间。基础换热模块100和弯管式基础换热模块200可以在制造工厂模块化预制，而后运到核反应堆现场进行组装，便于施工安装。
图13是本发明一个具体实施例的热交换器入口联箱结构示意图。
请参考图1和图13，在本发明的一些实施方式中，入口管道11与热交换器通过入口联箱12连接，入口联箱12设有多个出口管124，多个出口管124分别与热交换器的并联连接的多组基础换热模块100相连接。
请继续参考图13，入口联箱12由入口椭球封头121、出口椭球封头123、圆柱筒体122、入口125和出口管124组成。圆柱筒体122直径不小于入口管道11直径。入口椭球封头121通过入口125与入口管道11相连；出口椭球封头123通过出口管124与第一级热交换器20入口相连。当第一级热交换器20有多组并联的基础换热模块100组成时，在出口椭球封头123上可以连接多个沿其中轴线中心对称的出口管124，出口管124与并联的基础换热模块100一一对应。
在本发明的一些实施方式中，第二出口管道31与第二级热交换器 30通过第二出口联箱32连接，第二出口联箱32设有多个入口管，多个入口管分别与第二级热交换器30的并联连接的多组基础换热模块100相连接。
第一出口管道21与中间联箱23通过第一出口联箱22连接，第一出口联箱22的入口管与中间联箱23的侧出口150连接。
在一些实施例中，入口联箱12、第一出口联箱22、第二出口联箱32的结构相同，圆柱筒体122直径不小于入口管道11、第一出口管道21或第二出口管道31的直径。第一出口联箱22和第二出口联箱32的入口管即为入口联箱12的出口管124。
图14是本发明一个具体实施例的热交换器中间联箱示意图。
如图14所示，所述中间联箱23包括主连接管140和侧出口150，侧出口150设置在主连接管140的侧面，主连接管140的上下设置端部管板110，与第一级热交换器20和第二级热交换器30的基础换热模块100的端部管板110相匹配，并用螺栓通过法兰螺栓孔102相连接固定。侧出口150上安装管法兰111；主连接管140为直圆管形式，其管内径不小于端部管板110的管束开孔区的最大外接圆的直径，确保与端部管板110相连的管束内流体可以全部进入主连接管140；主连接管140的长度不大于一组基础换热模块100的长度；主连接管140的两端分别与两块端部管板110相连。侧出口150为圆管形式，其管内径不大于主连接管140；侧出口150可以由多个弯头和直管段组成，其长度和走向根据安装需要，使得中间联箱23能够与第一出口联箱22入口相连；侧出口150一端与主连接管140中部的侧面相连，另一端与管法兰111相连。
请继续参考图1，在本发明的一些实施方式中，余热排出系统70还包括热阱水箱50，各热交换器设置在热阱水箱50中，并且从上至下依次逐 级设置，例如，图1中的实施例中，第一级热交换器20位于第二级热交换器30的上方。
在本发明的一些实施方式中，热阱水箱50为一定装水量的水箱，也可以是江、河、湖、海等天然的天然冷却水源，热阱水箱50的水面高度高于第一级热交换器20和第二级热交换器30。
在本发明的一些实施方式中，反应堆系统10和余热排出系统70设置在安全壳60内，热阱水箱50上方设有回流收集槽51，回流收集槽50与安全壳60相连，并通过回流管线52与热阱水箱50连接。热阱水箱50与安全壳60、回流收集槽51、回流管线52一同配合使用；回流管线52的一端与回流收集槽51的底部相连，另一端位于热阱水箱50上方。
第一级热交换器20、中间联箱23、第二级热交换器30固定安装在热阱水箱50内；所述第一级热交换器20和第二级热交换器30的中心位置标高均高于所述反应堆系统10的热端1001的中心标高。根据不同应用场景，当反应堆系统10为核反应堆一次侧系统时，反应堆系统10的热端1001指反应堆堆芯；当反应堆系统10为核反应堆二次侧系统时，反应堆系统10的热端1001指一二次侧换热器的换热管束。
在反应堆系统10中产生的热量由流体携带，流体通过入口管道11依次进入各级热交换器(第一级热交换器20和第二级热交换器30)，由热交换器将热量传递给热阱水箱50，再通过第一出口管道21和第二出口管道31，流体返回反应堆系统10。整个过程中，流体在反应堆系统10内流体和各级热交换器内流体密度差的驱动下形成自然循环。
热阱水箱50中的水不断被加热直至饱和并蒸发，蒸汽经安全壳60内壁面冷却后冷凝为水，由回流收集槽51收集，并通过回流管线52返回到热阱水箱50实现长期的循环。安全壳60内壁面的热量经导热被带至外 壁面，并最终经对流换热等方式排入大气环境。事故过程中，随着系统持续带热以及堆芯衰变热的降低，系统带热能力最终与堆芯衰变热匹配，电厂不再可能发生更严重的事故工况。
在某些事故条件下(如LOCA事故)或者事故的不同阶段，若需要更多余热排出能力，可以根据触发信号(如稳压器低压力)，增加打开出口隔离阀的数量，这使得来自反应堆系统10的流体进入多级热交换器，将热量传递给热阱水箱50。这使得回到反应堆系统10的流体的焓值更低。整个过程中，流体同样在密度差的驱动下形成自然循环。
图15是本发明另一个具体实施例的反应堆用非动能余热排出系统的结构示意图。
根据不同核反应堆需要应对的事故的不同，可以在第一级热交换器20和第二级热交换器30的基础上，增添更多级的热交换器。如图7所示，可以设置第三级热交换器40，在第二级热交换器30和第三热交换器40之间设置第二中间联箱33，具体为，第二级热交换器30的出口第二中间联箱33的入口相连；第二中间联箱33的出口与第三级热交换器40的入口相连；第二中间联箱33的出口与第二出口联箱32的入口相连；第三级热交换器40的出口与第三出口联箱42的入口相连。以更加灵活地应对各种不同事故对于余热排出的需要。当然本发明并不仅限于设置二级或三级热交换器，可以根据实际需求设置不同数量的热交换器。
根据上述的核反应堆用非能动余热系统，本发明还提供一种核反应堆用非能动余热排出方法，包括以下步骤。
步骤S1，设置多级热交换器，将相邻两级热交换器之间分别通过中间联箱连接，所述中间联箱设有侧出口；
步骤S2，将反应堆系统的热端通过入口管道与第一级热交换器入口 连接；
步骤S3，将所述侧出口和最后一级热交换器出口分别通过出口管道连接至和反应堆系统的冷端，形成多级换热回路；
步骤S4，在所述入口管道和所述各出口管道上分别设置隔离阀；
步骤S5，在反应堆系统正常运行时，使所述入口管道上的隔离阀处于打开状态，使各出口管道上的隔离阀处于关闭状态；
步骤S6，当发生事故情况后，打开各所述出口管道上的隔离阀，形成连通的流体的循环回路，由反应堆系统产生的热量由流体携带，从所述热端通过所述入口管道通过多级热交换器进行换热，传递完热量的流体再通过所述出口管道返回至所述反应堆系统的冷端，形成循环。
进一步地，根据不同事故或事故的不同阶段选择使用热交换器的级数。
以上所述仅为本申请的优选实施例而已，并不用于限制本申请，对于本领域的技术人员来说，本申请可以有各种更改和变化。凡在本申请的精神和原则之内，所作的任何修改、等同替换、改进等，均应包含在本申请的保护范围之内。

Claims (10)

  1. 一种核反应堆用非能动余热排出系统，其特征在于，包括：
    反应堆系统，其包括热端和冷端，所述热端向外输出流体，所述冷端向内输入流体；
    余热排出系统，其包括多级热交换器，相邻两级热交换器之间分别通过中间联箱连接；
    其中，所述热端通过入口管道与第一级热交换器入口连接；所述中间联箱设有侧出口，所述侧出口和最后一级热交换器出口分别通过出口管道连接至所述冷端，形成多级换热回路；所述入口管道和各出口管道上分别设有隔离阀。
  2. 根据权利要求1所述的核反应堆用非能动余热排出系统，其特征在于，所述热交换器包括多组基础换热模块，所述基础换热模块由换热管束和设置在所述换热管束两端的端部管板组成，所述换热管束包括多个按照预定顺序排列的换热管，所述端部管板上设有与所述换热管对应的通孔。
  3. 根据权利要求2所述的核反应堆用非能动余热排出系统，其特征在于，所述热交换器的所述多组基础换热模块并联和/或串联连接。
  4. 根据权利要求3所述的核反应堆用非能动余热排出系统，其特征在于，所述入口管道与所述热交换器通过入口联箱连接，所述入口联箱设有多个出口管，多个出口管分别与所述热交换器的并联连接的多组基础换热模块相连接。
  5. 根据权利要求3所述的核反应堆用非能动余热排出系统，其特征在于，所述出口管道与所述热交换器通过出口联箱连接，所述出口联箱设有多个入口管，多个入口管分别与所述热交换器的并联连接的多组基础换热模块相连接。
  6. 根据权利要求2所述的核反应堆用非能动余热排出系统，其特征在于，所述换热管束的换热管为直管或弯管。
  7. 根据权利要求1所述的核反应堆用非能动余热排出系统，其特征在于，所述余热排出系统还包括热阱水箱，所述多级热交换器设置在所述热阱水箱中，并且从上至下依次逐级设置。
  8. 根据权利要求7所述的核反应堆用非能动余热排出系统，其特征在于，所述热阱水箱为一定装水量的水箱或天然冷却水源，所述热阱水箱的水面高度高于所述第一级热交换器。
  9. 根据权利要求8所述的核反应堆用非能动余热排出系统，其特征在于，所述反应堆系统和余热排出系统设置在安全壳内，所述热阱水箱上方设有回流收集槽，所述回流收集槽与安全壳相连，并通过回流管线与所述热阱水箱连接。
  10. 一种核反应堆用非能动余热排出方法，其特征在于，包括以下步骤：
    设置多级热交换器，将相邻两级热交换器之间分别通过中间联箱连接， 所述中间联箱设有侧出口；
    将反应堆系统的热端通过入口管道与第一级热交换器入口连接；
    将所述侧出口和最后一级热交换器出口分别通过出口管道连接至和反应堆系统的冷端，形成多级换热回路；
    在所述入口管道和所述各出口管道上分别设置隔离阀；
    在反应堆系统正常运行时，使所述入口管道上的隔离阀处于打开状态，使各出口管道上的隔离阀处于关闭状态；
    当发生事故情况后，打开各所述出口管道上的隔离阀，形成连通的流体的循环回路，由反应堆系统产生的热量由流体携带，从所述热端通过所述入口管道通过多级热交换器进行换热，传递完热量的流体再通过所述出口管道返回至所述反应堆系统的冷端，形成循环。
PCT/CN2023/096007 2022-09-14 2023-05-24 核反应堆用非能动余热排出系统及方法 WO2024055628A1 (zh)

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