Multi-natural circulation coupled heat removal device for marine nuclear power supply

Abstract

The application discloses a kind of marine nuclear power supply with multiple natural circulation coupling heat removal device, it is related to nuclear reactor safety technical field, its technical solution key points are: including integrated pressure vessel structure, energy conversion and residual heat removal integrated design loop structure, condenser cooling water loop structure, the energy conversion and residual heat removal integrated design loop structure is connected with integrated pressure vessel structure and condenser cooling water loop structure respectively.The application carries out research to the integrated pressure vessel and energy conversion and residual heat removal integrated system designed in marine nuclear power supply, forms three natural circulations respectively in integrated pressure vessel, secondary circuit and condenser seawater section, each natural circulation is coupled into an organic whole by steam generator heat pipe and condenser heat pipe, relies on multiple natural circulation coupling to remove residual heat of reactor core, guarantees nuclear reactor shutdown safety.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of nuclear reactor safety, more particularly, it relates to a multi-natural circulation coupled heat removal device for marine nuclear power supply. BACKGROUND

[0002] Nuclear power is a way of generating electricity using self-sustaining chain fission reactions of fissile nuclides. At present, nuclear power is commonly used in land-based nuclear reactor devices to provide power supply for land power grids. China has abundant marine resources, and the vast sea area of the islands to be developed, offshore drilling platforms, seabed exploration and deep-sea exploration stations require stable and reliable power supply. Due to the complex deep-sea environment and the extremely high requirements for equipment, the traditional power supply method often fails to meet the demand, and the small nuclear power supply in the marine environment has become an important energy choice in the process of marine resource development due to its high energy density, long service life and stable and reliable characteristics, and has broad application prospects in the field of marine resource development.

[0003] The existing marine nuclear power system design mostly follows or borrows from the original ship nuclear power technology, and the system composition is relatively complex, the construction and maintenance are difficult, and the cost and cycle have great uncertainty. Most small nuclear power designs adopt active and passive safety system design, and the system is complex, which makes it difficult to arrange equipment and structure for the marine nuclear power system. Due to the different temperatures of each part of the fluid and even the phase change, there is a density difference between each part of the fluid. When the height of the cold fluid is higher than that of the hot fluid, natural convection phenomenon will occur under the influence of buoyancy. The flow in the pipeline is also called natural circulation. The establishment and flow of natural circulation are affected by the driving force of the height difference between the cold and hot fluids, the resistance along the flow passage, the local resistance brought by the equipment such as valves, bends, flow distribution plates, heat exchangers and the like in the flow passage, and the heat exchange between the fluid or working medium in the circulation pipeline and the cold and hot sources. The key parameter of natural circulation flow exists fluctuation, and the size of the driving force also determines whether the natural circulation flow can be completely established and stably operated. The heat transfer capacity of the entire loop also has great uncertainty.

[0004] Therefore, the present application aims to provide a multi-natural circulation coupled heat removal device for marine nuclear power supply to solve the above problems. SUMMARY

[0005] The application aims to provide a multi-natural circulation coupled heat removal device for marine nuclear power supply.

[0006] The application achieves the above technical purpose by the following technical scheme: a multi-natural circulation coupled heat removal device for marine nuclear power supply, comprising an integrated pressure vessel structure, an energy conversion and residual heat removal integrated design loop structure, and a condenser cooling water loop structure, wherein the energy conversion and residual heat removal integrated design loop structure is connected with the integrated pressure vessel structure and the condenser cooling water loop structure respectively.

[0007] The integrated pressure vessel comprises a heat exchanger, a pressure stabilizer system, and a temperature control heating system; the heat exchanger is a plate heat exchanger, the pressure stabilizer system is arranged on a support platform above the side of the pressure vessel, and the temperature control heating system is used for automatically cutting off power according to the highest temperature in the reactor.

[0008] The energy conversion and residual heat removal integrated design loop comprises a steam turbine simulation body, a condenser, a deaerator simulation body, a feedwater pump simulation body pipeline, a No. 1 water tank, and valves; the steam turbine simulation body is used as a resistance piece, the condenser is a tube-shell heat exchanger, steam passes through the shell side and cooling water passes through the tube side, the condenser itself has a certain elevation difference to improve the natural circulation capacity of the tube side cooling water, the deaerator is simulated by using valves, and the feedwater pump simulation body pipeline is simulated by using valves; and the No. 1 water tank is used for loop water filling and draining.

[0009] The condenser cooling water loop comprises a condenser tube side and a No. 2 water tank; the condenser tube side adopts a U-shaped tube arrangement mode, the condenser is arranged with multiple groups of independent pipelines therein, and is synchronously connected to the No. 2 water tank for cooling, so as to ensure the natural circulation capacity, the flow distribution of each loop, and the heat removal balance; and the No. 2 water tank is used for simulating the low-temperature marine flow environment by slowly injecting and discharging equal-flow cold water.

[0010] The application is further provided with the following arrangement: the heat removal device is provided with thermal insulation materials, and the thermal insulation materials are wrapped on the heat removal device to reduce energy leakage.

[0011] The application is further provided with the following arrangement: the heat removal device further comprises measuring instruments, and the measuring instruments are arranged on the heat removal device to measure and monitor the flow, temperature, pressure, and liquid level.

[0012] The application further provides that the measuring instrument is a flow meter, a thermocouple, a pressure gauge or a liquid level gauge, and is used for measuring and monitoring the flow, temperature, pressure and liquid level of the heat exhaust device.

[0013] The application further provides that the pressure stabilizer system comprises a pressure stabilizer tank, a pressure stabilizer cylinder and a safety valve, and is arranged on a support platform above the pressure container.

[0014] The application further provides that the integrated pressure container structure is designed to have a running pressure of 1 MPa, a fluid temperature range of 135-180 DEG C, and a single phase in the test heating section, and the pressure container is made of 304 stainless steel, and the bottom is provided with a heating element through hole and a core simulation body, which are used for simulating the heat release of the core in an electric heating mode.

[0015] The application further provides that the running environment of the energy conversion and residual heat exhaust integrated design loop structure is designed to have a running pressure of 0.2 MPa, a temperature range of 30-120 DEG C, and a single phase-two phase fluctuation state of the fluid working medium, and the phase state changes between the steam generator and the condenser, which are used for avoiding flow instability.

[0016] The application further provides that the running environment of the condenser cooling water loop structure is designed to have a normal pressure condition, a temperature range of 20-80 DEG C, and a single phase state of the fluid working medium, and the fluid working medium is boiled, and the natural circulation flow occurs on the condenser tube side, the heat source comes from the condenser steam heat release, and the cold source comes from the cold water in the water tank.

[0017] In summary, the application has the following beneficial effects:

[0018] 1. The application can form three natural circulations in the integrated pressure container, the secondary circuit and the condenser seawater section, respectively, and each natural circulation is coupled into an integrated system through the steam generator heat transfer pipe and the condenser heat transfer pipe, and relies on the multi-natural circulation coupling to discharge the residual heat of the core, so that the safety of the nuclear reactor shutdown can be ensured.

[0019] 2. The application can carry out system simulation, local area fine numerical simulation and multi-loop natural circulation coupling heat exhaust system experimental research, carry out low-difference high-flow-resistance single-phase-two-phase coupling natural circulation system flow heat exchange characteristic research, verify the system operation feasibility and robustness, obtain the system transient response characteristic and stable operation boundary interval, and be used for supporting the integrated marine nuclear power system design and equipment structure optimization. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1is a structural schematic view of a multi-natural circulation coupled heat removal device for a marine nuclear power source in an embodiment of the present application;

[0021] Figure 2 is a simulation schematic view of a device prototype in a modeling experiment in an embodiment of the present application.

[0022] In the figure: 1, heat exchanger; 2, electric heater; 3, stabilizer tank; 4, safety valve; 5, pressure gauge; 6, stabilizer gas cylinder; 7, water pump one; 8, No. 1 water tank; 9, water pump two; 10, flow meter; 11, thermocouple; 12, condenser; 13, steam turbine simulation body; 14, deaerator simulation body; 15, water pump three; 16, No. 2 water tank. DETAILED DESCRIPTION

[0023] The following will be described in detail in combination with the accompanying Figures 1-2 The present application will be further described in detail.

[0024] Embodiment: A multi-natural circulation coupled heat removal device for a marine nuclear power source, comprising an integrated pressure vessel structure (a primary circuit), an energy conversion and residual heat removal integrated design circuit structure (a secondary circuit), and a condenser 12 cooling water circuit structure (a tertiary circuit), the energy conversion and residual heat removal integrated design circuit structure is connected with the integrated pressure vessel structure and the condenser 12 cooling water circuit structure, respectively, a thermal insulation material is wrapped on the heat removal device for reducing energy leakage, and a measuring instrument is fixedly arranged on the heat removal device for measuring and monitoring flow, temperature, pressure and liquid level.

[0025] The thermal hydraulic operation parameter design in the embodiment is shown in Table 1:

[0026] Table 1 Thermal hydraulic operation parameter design table

[0027] Parameters Primary loop Secondary loop Tertiary loop Design pressure ~1.5 MPa ~0.5 MPa ~0.1 MPa Operating pressure ~1.0 MPa ~0.1 MPa (atmospheric pressure) ~0.1 MPa Loop temperature range 135℃～170℃ 135℃～170℃ 135℃～170℃ Heating power 1 KWe ~ 100 KWe \ \ Water tank temperature \ 80℃ 23℃ Water tank volume \ 1m 3 ]] 2m 3 ]]> Design scheme Integrated pressure vessel Dual loop, equipment sharing Multiple independent circuits

[0028] The integrated pressure vessel is specifically designed to have a running pressure of 1 MPa, a fluid temperature range of 135-180℃, and a single phase in the test heating section, and the pressure vessel is processed by using 304 stainless steel, and the bottom is provided with a heating element through hole and a core simulation body for simulating core heat release in an electric heating mode, wherein the integrated pressure vessel is arranged on a support platform, and a distance of at least 0.2 m is arranged between the integrated pressure vessel and the support platform, so as to facilitate drainage and arrangement of heating element lead wires, and a discharge passage is arranged below the integrated pressure vessel for container drainage.

[0029] The integrated pressure vessel (primary circuit) in the embodiment specifically comprises a heat exchanger 1, a pressure stabilizer system, and a temperature control heating system; the heat exchanger 1 is a plate heat exchanger 1, the pressure stabilizer system is provided with a pressure stabilizer tank 3, a supporting stable pressure cylinder 6, a safety valve 4, and a water injection pipeline, and is arranged on a support platform above the pressure vessel; the temperature control heating system can automatically cut off power supply according to the maximum temperature in the reactor core, constant power heating, or gradually reducing power according to the actual reactor core decay heat curve.

[0030] The outer surface of the integrated pressure vessel is coated with thermal insulation material, and the measuring instruments in the primary circuit specifically include a flow meter 10 (arranged at the descending section of the two loops, used for measuring the natural circulation flow of the primary circuit), a thermocouple 11 (arranged at the end of the ascending section, used for monitoring the temperature of the fluid and cutting off power supply in time; arranged at the end of the descending section), a pressure gauge 5 (arranged at the pressure stabilizer tank 3, used for maintaining stable system pressure), and a liquid level meter (arranged in the pressure stabilizer tank 3 for liquid level monitoring, facilitating timely water replenishment).

[0031] The operating environment of the integrated design loop of energy conversion and residual heat removal (secondary circuit) is specifically that the design operating pressure is 0.2 MPa, the temperature range is 30-120℃, the fluid working medium is in a single-phase-two-phase fluctuating state, and the phase state changes between the steam generator and the condenser 12, which is used to avoid the situation that the flow instability easily occurs due to the reliance on natural circulation driving.

[0032] The integrated design loop of energy conversion and residual heat removal (secondary circuit) in the embodiment specifically comprises a steam turbine simulation body 13, a condenser 12, a deaerator simulation body 14, a feedwater pump simulation body pipeline, a No. 1 water tank 8, and a valve; the steam turbine simulation body 13 is a steam turbine in the natural circulation process, which does not output shaft power and does not generate electric energy, and is considered to be static by the cascade, and there is no heat exchange with the surrounding environment, so it is used as a resistance piece; in the embodiment, a resistance valve is used for simulation, the pressure difference between the inlet and outlet is concerned, the flow rate and other parameters determined by the size, and bypass pipelines are arranged on the two loops.

[0033] The condenser 12 is similar to the real condenser 12 equipment, the natural circulation requires high heat exchange capacity, and the experimental modeling should be as accurate as possible, therefore, the condenser 12 equipment close to the design scheme of the ocean nuclear power source is adopted in the embodiment, the annular condenser 12 is used in the overall design of the ocean nuclear power source, the upper part is directly connected to the end of the steam turbine volute, and there is no fine pipeline in the middle, in the embodiment, a tube-in-shell heat exchanger 1 is adopted, the steam goes to the shell side, and the cooling water goes to the tube side, the condenser 12 itself has a certain elevation difference, which improves the natural circulation capacity of the tube side cooling water, the condenser 12 has a high, thin, and long overall shape, and a structure with small flow resistance is selected.

[0034] In the deaerator simulation body 14, the deaerator does not have heat exchange function, and in the residual heat discharge stage, it can only bring certain flow resistance, and generally the deaerator adopts spray valve design, so the flow resistance will be greatly increased, therefore, in the natural circulation heat discharge stage, it is necessary to bypass the deaerator to improve the natural circulation capacity of the whole system, in the embodiment modeling, the valve is also used to simulate the deaerator, and bypass pipelines are arranged on the two loops respectively.

[0035] In the pump equipment and other rotating machinery in the feedwater pump simulation body pipeline under the condition of no shaft power input and output, the thermal hydraulic characteristics are similar to those of the steam turbine, and there is no heat exchange in it, in the embodiment modeling, the valve is also used for modeling, because in the experimental research, the natural circulation heat discharge starting, transition, steady state, transient and other characteristics are also researched, therefore, the feedwater pump circuit, orifice plate resistance simulation body circuit and bypass circuit are arranged in the circuit.

[0036] In the embodiment, the No. 1 water tank 8 is used for circuit water filling and draining, and the specific design volume is about 1 of the No. 1 water tank 8, which is at the same height with the feedwater pump 7, the No. 1 water tank 8 is connected with the natural circulation loop through the pipeline, and is filled with water before operation and stored water after operation, but is isolated from the loop in the actual operation of the natural circulation.

[0037] All the equipment in the secondary loop is covered with thermal insulation material, and the heat leakage rate is less than 1%, the water tank and the lowest end of the loop are provided with water filling and draining ports for cleaning and fluid emptying in the equipment, and support structures are arranged for the key equipment, especially the condenser 12, the flow meter 10 (arranged at the inlet and outlet sections of the steam generator), the thermocouple 11 (arranged at the inlet and outlet sections of the steam generator, the inlet and outlet of the condenser 12, the No. 1 water tank 8, and real-time monitoring), the pressure gauge 5 (arranged at the uppermost end and the lowest end of the secondary loop), and the liquid level meter (arranged in the water level monitoring of the No. 1 water tank 8 and the bypass water level monitoring outside the steam generator, and real-time monitoring of the phase change height of the steam generator).

[0038] The operation environment of the condenser 12 cooling water circuit (three loop) is specifically designed as normal pressure condition, the temperature range is 20-80℃, the fluid working medium is in single phase state, boiling occurs, natural circulation flow occurs in the condenser 12 pipe side, the heat source comes from the steam heat release of the condenser 12, the cold source comes from the cold water in the water tank, and in the marine nuclear power source design, it comes from the seawater, in the embodiment modeling, the slow injection and discharge of cold water with equal flow in the No. 2 water tank 16 are used to simulate the marine flow low temperature environment.

[0039] The condenser 12 cooling water circuit (three circuits) in this embodiment specifically includes the condenser 12 tube side and the No. 2 water tank 16; wherein the condenser 12 tube side adopts a U-shaped tube arrangement, the condenser 12 is arranged with multiple groups of independent pipelines, which are synchronously connected to the No. 2 water tank 16 for ensuring the natural circulation capacity, and the flow distribution and heat discharge balance of each loop.

[0040] The No. 2 water tank 16 has a water tank volume 2 and an open design, the top side and the bottom side slowly inject and discharge cold water with equal flow, the water injection temperature is 23℃, the condenser 12 tube side pipeline is connected below the water tank side (not on the same side with the cold water injection and discharge outlet), the water inlet and the water outlet have a certain height difference, a water pump is arranged between the water tank and the condenser 12 cooling water inlet pipe; wherein the measuring instruments specifically include a flow meter 10 (arranged at the condenser 12 tube side inlet section), a thermocouple 11 (arranged at the condenser 12 tube side inlet section, outlet section and cold water pipe inlet section), and a liquid level meter (arranged in the No. 2 water tank 16).

[0041] Working principle:

[0042] In order to form natural circulation in the multi-loop coupling system respectively, the coupling discharge core simulation body heat is simulated, and the system operation characteristics under several working conditions are verified, including system starting, forced circulation to natural circulation transition, natural circulation stable operation, natural circulation system response under power transient condition, and the specific steps are as follows: system equipment and debugging, one loop sealing inspection, water injection in the No. 1 and No. 2 water tanks 16, and detection of whether the temperature meets the requirements; water is injected into the one loop from the top water injection pipeline, so that the pressure vessel is filled with water, and the exhaust operation is carried out; open the pressure stabilizing cylinder 6, adjust the air volume, and maintain the pressure in the pressure stabilizer tank 3 at 1.0 MPa, while ensuring that the water level in the pressure stabilizer tank 3 is above the warning line; open the No. 1 water tank 8 isolation valve, start the two-loop water pump two 9, and at the same time open the electric heater 2, so that the two-loop circulating water temperature reaches 36℃; after the temperature meets the requirements, close the electric heater 2; open the electric heater 2, adjust the power to be above the set value, continue to heat to make the one loop water temperature reach 165℃, close the No. 1 water tank 8 isolation valve, and open the energy conversion loop valve, so that the one loop heat is continuously taken away in the forced circulation mode, and the natural circulation of the one loop is established, and the one loop flow and the temperature values of each temperature measuring point at this time are recorded; reduce the power of the electric heater 2 to the residual heat level of the core, close the two-loop water pump two 9 and the three-loop water pump three 15, so that the two-loop and three-loop establish multi-loop coupling natural circulation according to their own density difference, and the loop flow and the temperature values of each temperature measuring point are recorded in real time (multi-loop natural circulation starting, transition and stable operation characteristics); increase the power of the electric heater 2 to the set value, and record the transient changes of the loop flow, the temperature values of each temperature measuring point and other parameters in the multi natural circulation loop; reduce the power of the electric heater 2 to the set value, and record the transient changes of the loop flow, the temperature values of each temperature measuring point and other parameters in the multi natural circulation loop; cut off the power of the electric heater 2, open the two-loop water pump two 9 and the three-loop water pump three 15, and continuously operate to make the temperature in the two loops drop to room temperature, close the water pump, close the pressure stabilizing cylinder 6, carry out loop drainage, arrange the equipment, and complete the experiment.

[0043] The specific embodiment is only an explanation of the application, and is not a limitation of the application. Those skilled in the art can make modifications to the embodiment without creative contribution according to the needs after reading the specification, and the application is protected by the patent law as long as it is within the scope of the claims.

Claims

1. A multi-natural circulation coupled heat removal device for marine nuclear power sources, characterized by: It includes an integrated pressure vessel structure, an energy conversion and waste heat discharge integrated design circuit structure, and a condenser (12) cooling water circuit structure, wherein the energy conversion and waste heat discharge integrated design circuit structure is connected to the integrated pressure vessel structure and the condenser (12) cooling water circuit structure respectively; The integrated pressure vessel comprises a heat exchanger (1), a pressurizer system and a temperature control and heating system; the heat exchanger (1) is a plate heat exchanger (1) connected to an energy conversion and waste heat discharge integrated design circuit; the pressurizer system has a pressurizer tank (3), a matching pressure-stabilizing gas cylinder (6), a safety valve (4) and a water injection pipe, and the pressurizer system is arranged on a supporting platform above the side of the pressure vessel and connected to the energy conversion and waste heat discharge integrated design circuit structure; the temperature control and heating system is used for heating and automatically cuts off the power according to the highest temperature in the pile; The energy conversion and waste heat discharge integrated design loop includes a steam turbine simulation body (13), a condenser (12), a deaerator simulation body (14), a feed water pump simulation body pipeline, a No. 1 water tank (8) and a valve; the steam turbine simulation body (13) is treated as a resistance component, the condenser (12) adopts a shell and tube heat exchanger (1), the steam flows through the shell side, and the cooling water flows through the tube side. The condenser (12) itself has a certain elevation difference, which improves the natural circulation capacity of the cooling water on the tube side. The deaerator is simulated using a valve, and bypass pipelines are respectively set on the two loops. In the natural circulation heat discharge stage, the deaerator is bypassed and isolated. The feed water pump simulation body pipeline is simulated using a valve; the steam turbine simulation body (13), the condenser (12), the deaerator simulation body (14), and the feed water pump simulation body pipeline are connected in sequence through pipelines, and the No. 1 water tank (8) is connected to the loop where the integrated pressure vessel structure is located, which is used for loop filling and drainage; The condenser (12) cooling water circuit includes a condenser (12) tube side and a No. 2 water tank (16); the condenser (12) tube side adopts a U-shaped tube arrangement, and multiple independent groups of pipelines are arranged in the condenser (12), which are synchronously connected to the cooling No. 2 water tank (16) to ensure the natural circulation capacity and the flow distribution and heat discharge balance of each loop; the No. 2 water tank (16) is used to simulate the low-temperature environment of ocean flow by slowly injecting and discharging equal flow cold water, and three natural cycles are formed in the integrated pressure vessel, the energy conversion and waste heat discharge integrated design circuit and the condenser (12) cooling water circuit respectively. Each natural cycle is coupled into one through the steam generator heat transfer pipe and the condenser (12) heat transfer pipe. The fluid working medium of the energy conversion and waste heat discharge integrated design circuit is in a single-phase-two-phase fluctuation change state, and a phase change occurs between the steam generator and the condenser (12) to avoid flow instability.

2. The multi-natural circulation coupled heat removal device for marine nuclear power according to claim 1 is characterized by: The heat dissipation device is provided with a heat-insulating material, and the heat-insulating material is coated on the heat dissipation device to reduce energy leakage.

3. The multi-natural circulation coupled heat removal device for marine nuclear power according to claim 1 is characterized by: The integrated pressure vessel structure in the test heating section is specifically designed to have an operating pressure of 1 MPa, a fluid temperature range of 135-180°C, and is single-phase. The pressure vessel is made of 304 stainless steel and has a heating element through-hole and a core simulation body at the bottom for simulating core heat release by electric heating.

4. The multi-natural circulation coupled heat removal device for marine nuclear power according to claim 1 is characterized by: The operating environment of the integrated energy conversion and waste heat removal loop structure is specifically designed to have a design operating pressure of 0.2 MPa and a temperature range of 30-120°C.

5. The multi-natural circulation coupled heat removal device for marine nuclear power according to claim 1 is characterized by: The operating environment of the cooling water circuit structure of the condenser (12) is specifically designed to be under normal pressure conditions with a temperature range of 20-80°C. The fluid working medium is in a single-phase state and boils, and natural circulation occurs on the side of the condenser (12) tube. The heat source comes from the heat released by the steam of the condenser (12), and the cold source comes from the cold water in the water tank.

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