阅读说明：本技术 一种基于环形气冷器的非能动余热排出系统 (Passive residual heat removal system based on annular air cooler ) 是由 向清安 邓坚 卢庆 江光明 高颖贤 刘兆东 邓纯锐 邱志方 刘余 张明 武小莉 于 2020-11-19 设计创作，主要内容包括：本发明公开了一种基于环形气冷器的非能动余热排出系统,包括至少两个独立的余热排出子系统和共用的补水箱,其中,每个余热排出子系统包括：由换热水箱和热交换器组成的换热装置,由下降腔、气冷管、上部环形联箱和下部环形联箱组成的环形气冷器,以及环形气冷器入口电动阀和出口电动阀；将气冷管内的热气体作为上升段,下降腔内的冷气体为下降段,依靠冷热气体的密度差和位差在环形气冷器和换热装置之间形成自然循环流动换热,从而在堆芯正常停堆或事故停堆后,实现安全、可靠地排出堆芯内的剩余热量,并保证燃料包壳、压力容器、反应堆腔室壁面的温度不超过允许温度。(The invention discloses a passive residual heat removal system based on an annular air cooler, which comprises at least two independent residual heat removal subsystems and a shared water supplementing tank, wherein each residual heat removal subsystem comprises: the heat exchange device comprises a heat exchange water tank and a heat exchanger, an annular air cooler consisting of a descending cavity, an air cooling pipe, an upper annular header and a lower annular header, an inlet electric valve and an outlet electric valve of the annular air cooler; the hot gas in the gas cooling pipe is used as an ascending section, the cold gas in the descending cavity is used as a descending section, and natural circulation flow heat exchange is formed between the annular gas cooler and the heat exchange device by means of density difference and potential difference of the cold gas and the hot gas, so that after the reactor core is normally shut down or accident shut down, the residual heat in the reactor core is safely and reliably discharged, and the temperature of the fuel cladding, the pressure vessel and the wall surface of the reactor cavity is ensured not to exceed the allowable temperature.)

1. A passive residual heat removal system based on an annular air cooler is characterized by comprising at least two residual heat removal subsystems and a water supplementing tank, wherein all the residual heat removal subsystems are connected to the water supplementing tank;

each waste heat discharge subsystem comprises an annular air cooler, a heat exchange device, an inlet electric valve and an outlet electric valve of the annular air cooler; the annular gas cooler is positioned in the reactor cavity and surrounds the reactor pressure vessel; the heat exchange device is connected with the water replenishing tank, and an exhaust pipe is arranged at the top of the heat exchange device and used for exhausting water vapor;

after normal shutdown or accident shutdown, the shutdown signal triggers and opens an electric valve at the outlet and an electric valve at the inlet of the annular gas cooler of the waste heat discharge subsystem, so that the annular gas cooler is communicated with the heat exchange device to form a closed circulating flow loop.

2. The annular air cooler-based passive residual heat removal system according to claim 1, wherein the heat exchanging device comprises a heat exchanging water tank and a heat exchanger;

supercooled water is filled in the heat exchange water tank, and the heat exchanger is immersed in the supercooled water.

3. The annular air cooler-based passive residual heat removal system according to claim 2, wherein the annular air cooler comprises a descending cavity, air cooling pipes, an upper annular header and a lower annular header;

the outer wall surface of the descending cavity is fixedly arranged on the inner wall surface of the reactor cavity, the top of the descending cavity is communicated with the heat exchanger through an electric valve at the inlet of the annular air cooler, and the bottom of the descending cavity is communicated with the lower annular header;

the air cooling pipes are vertically arranged between the inner wall surface of the descending cavity and the outer wall surface of the pressure container at equal intervals and are circumferentially arranged; the bottom of the air cooling pipe is connected with the lower annular header, and the top of the air cooling pipe is connected with the upper annular header;

the upper annular header is connected with the heat exchanger through an outlet electric valve of the annular air cooler; the bottom of the heat exchanger is higher than the top of the air-cooled tube.

When the core heat in the pressure vessel is radiated to the air-cooling pipe through the wall surface of the pressure vessel, the gas in the air-cooling pipe flows upwards to the heat exchanger, is cooled by the super-cooling water in the heat exchange water tank, and then flows back to the air-cooling pipe through the descending cavity to perform reciprocating circulation.

4. The annular air cooler-based passive residual heat removal system according to claim 3, wherein an inner wall surface of the descending cavity is provided with a reflective insulation layer.

5. The annular air cooler-based passive residual heat removal system according to claim 3, wherein the annular air cooler further comprises an annular support lattice; the air cooling pipe is fixed on the inner wall surface of the descending cavity through an annular supporting grid.

6. The annular gas cooler-based passive residual heat removal system according to claim 3, wherein the reactor chamber is provided with reflective insulation layers on the inner sides of the upper wall and the lower wall.

7. The passive residual heat removal system based on the annular air cooler according to claim 3, wherein the cross section of the air cooling pipe is circular, rectangular, trapezoidal or trapezoidal with inner and outer arcs.

8. The annular air cooler-based passive residual heat removal system of claim 1, wherein the residual heat removal subsystem is connected with the make-up water tank through a make-up water electric valve;

when the water level in the heat exchange water tank is reduced to a preset low water level, a low water level signal triggers a water replenishing electric valve corresponding to the water replenishing tank to open, and water is filled into the heat exchange water tank; when the water level in the heat exchange water tank rises to a preset high water level, the high water level signal triggers the water replenishing electric valve corresponding to the water replenishing tank to close.

9. The annular air cooler-based passive residual heat removal system as claimed in claim 1, wherein the annular air cooler inlet electric valve, the outlet electric valve and the water replenishing electric valve are powered by reliable power sources.

Technical Field

The invention relates to the technical field of cooling systems in the nuclear industry, in particular to a passive residual heat removal system based on an annular air cooler.

Background

After a nuclear reactor shutdown, there is residual heating in the core and a considerable time duration due to the decay of the remaining fission and fission products in the core. The heat of the core can cause the temperature of the core fuel and the core coolant to rise, so that the fuel elements are damaged and even melted, and a large amount of radioactive substances are released outwards, thereby causing a nuclear safety accident. Therefore, a safety level waste heat removal system is required to carry the heat remaining in the core to the final hot-trap. Different from a pressurized water reactor, the liquid metal cooling reactor adopts low-melting-point metal as a coolant, such as sodium-potassium alloy, lead-bismuth alloy and the like, and the liquid metal coolant has the characteristics of large specific heat capacity and heat conductivity, low melting point and high boiling point, so that the liquid metal cooling reactor has the advantages of good heat conduction performance, high heat efficiency and large power, and meanwhile, the metal cooling reactor is compact in design, small in size, large in natural circulation capacity and low in noise, and is regarded as one of preferable reactor types of a fourth-generation advanced nuclear energy system.

In the process that the residual heat of the reactor core is brought out to a final hot well (such as the atmosphere) by a water-cooled wall, the existing residual heat removal system of the liquid metal cooling reactor adopts an active circulating cooling mode based on a water cooler and needs a power supply to drive a pump, and even if a redundant design is adopted, once the power supply fails, the active system fails; the passive residual heat removal system based on the water cooler is adopted, and the air cooler and the air cooling tower are adopted, so that the system is complex and high in construction cost, and the requirements of reactor miniaturization, compact arrangement and the like are not met.

Disclosure of Invention

The invention aims to solve the technical problems that the existing liquid metal cooling reactor system is complex and high in construction cost, and cannot meet the requirements of miniaturization, compact arrangement and the like of the reactor. The invention provides a passive residual heat removal system based on an annular gas cooler, which is used for meeting the requirements of reactor miniaturization, compact arrangement and the like, so that residual heat in a reactor core can be safely and reliably removed after normal reactor shutdown or accident shutdown of the reactor core, and the temperatures of a fuel cladding, a pressure vessel and the wall surface of a reactor cavity are not higher than allowable temperatures.

The invention is realized by the following technical scheme:

a passive residual heat removal system based on an annular air cooler comprises at least two residual heat removal subsystems and a water supply tank, wherein all the residual heat removal subsystems are connected to the water supply tank;

each waste heat discharge subsystem comprises an annular air cooler, a heat exchange device, an inlet electric valve and an outlet electric valve of the annular air cooler; the annular gas cooler is positioned in the reactor cavity and surrounds the reactor pressure vessel; the heat exchange device is connected with the water replenishing tank, and an exhaust pipe is arranged at the top of the heat exchange device and used for exhausting water vapor;

after normal shutdown or accident shutdown, the shutdown signal triggers and opens an electric valve at the outlet and an electric valve at the inlet of the annular gas cooler of the waste heat discharge subsystem, so that the annular gas cooler is communicated with the heat exchange device to form a closed circulating flow loop.

Further, the heat exchange device comprises a heat exchange water tank and a heat exchanger;

supercooled water is filled in the heat exchange water tank, and the heat exchanger is immersed in the supercooled water.

Further, the annular air cooler comprises a descending cavity, an air cooling pipe, an upper annular header and a lower annular header;

the outer wall surface of the descending cavity is fixedly arranged on the inner wall surface of the reactor cavity, the top of the descending cavity is communicated with the heat exchanger through an electric valve at the inlet of the annular air cooler, and the bottom of the descending cavity is communicated with the lower annular header;

the air cooling pipes are vertically arranged between the inner wall surface of the descending cavity and the outer wall surface of the pressure container at equal intervals and are circumferentially arranged; the bottom of the air cooling pipe is connected with the lower annular header, and the top of the air cooling pipe is connected with the upper annular header;

the upper annular header is connected with the heat exchanger through an outlet electric valve of an annular air cooler; the bottom of the heat exchanger is higher than the top of the air cooling pipe;

when the core heat in the pressure vessel is radiated to the air-cooling pipe through the wall surface of the pressure vessel, the gas in the air-cooling pipe flows upwards to the heat exchanger, is cooled by the super-cooling water in the heat exchange water tank, and then flows back to the air-cooling pipe through the descending cavity to perform reciprocating circulation.

Furthermore, a reflection heat insulation layer is arranged on the inner wall surface of the descending cavity.

Further, the annular air cooler further comprises an annular support grid; the air cooling pipe is fixed on the inner wall surface of the descending cavity through an annular supporting grid.

Furthermore, the inner sides of the upper wall and the lower wall of the reactor cavity are both provided with a reflection heat insulation layer.

Further, the cross section of the air cooling pipe is circular, rectangular, trapezoidal or trapezoidal with inner and outer arcs.

Further, the waste heat discharge subsystem is connected with the water replenishing tank through a water replenishing electric valve;

when the water level in the heat exchange water tank is reduced to a preset low water level, a low water level signal triggers a water replenishing electric valve corresponding to the water replenishing tank to open, and water is filled into the heat exchange water tank; when the water level in the heat exchange water tank rises to a preset high water level, the high water level signal triggers the water replenishing electric valve corresponding to the water replenishing tank to close.

Further, the annular air cooler inlet electric valve, the annular air cooler outlet electric valve and the annular air cooler water replenishing electric valve are powered by a reliable power supply.

According to the passive residual heat removal system based on the annular gas cooler, the annular gas cooler is compactly arranged around the pressure vessel of the reactor, the reactor core residual heat is taken out through the radiation heat exchange between the outer wall surface of the pressure vessel and the gas cooling pipes in the annular gas cooler, and the heat carrying effect is good; the radiation heat exchange capacity of the wall surface of the pressure vessel and the air cooling pipes is enhanced by designing the shape, the size (such as the length of 10cm, the width of 3cm, the wall thickness of 0.5cm, the air cooling pipe clearance of 3cm), the number (hundreds) and the arrangement of the air cooling pipes, and tightly attaching the inner wall surface of a descending cavity in the annular air cooler to a reflection heat insulation layer; the annular gas cooler and the heat exchange device form natural circulation flow heat exchange by means of density difference and potential difference of cold and hot gas, and water vapor formed in the heat exchange water tank is discharged through the exhaust pipe at the top of the annular gas cooler and the heat exchange device, so that residual heat in a reactor core is discharged more safely and reliably after the reactor core is normally shut down or is shut down by accident, and the temperature of a fuel cladding, a pressure vessel and the wall surface of a reactor cavity is not more than allowable temperature.

Drawings

The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principles of the invention. In the drawings:

fig. 1 is a schematic diagram of an embodiment of a passive residual heat removal system based on an annular air cooler according to the present invention.

FIG. 2 is a top view of the annular air cooler of FIG. 1 taken in a horizontal cross-section.

Fig. 3 is a schematic diagram of the radiative heat exchange between the pressure vessel and the annular gas cooler of fig. 1.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to examples and accompanying drawings, and the exemplary embodiments and descriptions thereof are only used for explaining the present invention and are not meant to limit the present invention.

Examples

For the sake of understanding, two waste heat removal subsystems are taken as an example for illustration. As shown in fig. 1 to 3, the system comprises a first waste heat removal subsystem and a second waste heat removal subsystem, and the first waste heat removal subsystem and the second waste heat removal subsystem share a water replenishing tank 300.

The first waste heat removal subsystem includes a first annular air cooler, a first heat exchange device, and inlet electrically operated valves 111 and 121 and outlet electrically operated valves 112 and 122 of the first annular air cooler.

The second waste heat removal subsystem includes the second annular air cooler, the second heat exchange device, and the inlet electric valves 211, 221 and the outlet electric valves 212, 222 of the second annular air cooler.

Specifically, after a normal shutdown or an accident shutdown, a shutdown signal triggers to open an outlet electric valve 112 or 122 and an inlet electric valve 111 or 121 arranged on the first annular gas cooler, so that the first annular gas cooler is communicated with the first heat exchange device to form a closed circulation flow loop; or the shutdown signal triggers the opening of the annular air cooler outlet electric valve 212 or 222 and the annular air cooler inlet electric valve 211 or 221 which are arranged on the second waste heat discharging subsystem, so that the second annular air cooler is communicated with the second heat exchanging device to form a closed circulation flow loop.

The first annular gas cooler is located in the reactor chamber 4 and surrounds the pressure vessel 3. The first annular air cooler comprises a first drop chamber 103, a plurality of first air-cooled tubes 105, a first lower annular header 104 and a first upper annular header 106.

The first heat exchange means includes a first heat exchange water tank 100 and a first heat exchanger 101, the first heat exchange water tank 100 contains the supercooled water, and the first heat exchanger 101 is immersed in the supercooled water. The top of the first heat exchange water tank 100 is provided with an exhaust pipe, and when the supercooled water in the first heat exchange water tank 100 is heated to a saturated state, water vapor is generated and then discharged through the exhaust pipe.

The bottom of the first heat exchanger 101 in this embodiment is higher than the top of the first air-cooling pipe 105, so as to increase the difference between the cold gas in the first heat exchanger 101 and the hot gas in the first air-cooling pipe 105, thereby enhancing the natural circulation flow.

The outer wall surface of the first downcomer chamber 103 is fixedly arranged on the inner wall surface of the reactor chamber 4, the top of the first downcomer chamber 103 is communicated with the first heat exchanger 101 through the inlet electric valves 111 and 121 of the first annular gas cooler, and the bottom of the first downcomer chamber 103 is communicated with the first lower annular header 104 through a pipeline.

Further, the first air-cooling pipes 105 are vertically arranged at equal intervals between the inner wall surface of the first descent chamber 103 and the outer wall surface of the pressure vessel 3, and are arranged in the circumferential direction.

The first air cooling pipe 105 can be a pipeline with a rectangular cross section, a pipeline with a trapezoidal cross section, a pipeline with an inner arc-shaped cross section and an outer arc-shaped cross section, and the specific size can be specifically set according to actual conditions. In the embodiment, a pipeline with a rectangular cross section is adopted, the size of the pipeline is 10cm in length, 3cm in width and 0.5cm in wall thickness, and the gap between every two adjacent first air cooling pipes 105 is set to be 3 cm. The bottom of the first gas-cooled pipe 105 is directly connected to the first lower annular header 104, the top of the first gas-cooled pipe 105 is directly connected to the first upper annular header 106, and the first upper annular header 106 is connected to the first heat exchanger 101 via the first annular gas cooler outlet electric valves 112, 122.

When the heat of the core in the pressure vessel 3 is radiated to the first air-cooling pipe 105 through the wall surface of the pressure vessel 3, the gas in the first air-cooling pipe 105 is heated, the volume is increased, the density is reduced, the gas flows upwards to the first heat exchanger 101, is cooled by the supercooled water in the first heat exchange water tank 100, and then flows back to each first air-cooling pipe 105 through the first descending cavity 103 to perform reciprocating circulation. When the supercooled water in the first heat exchange water tank 100 is heated to a saturated state, water vapor is generated and then discharged through the exhaust pipe.

The water level of the replenishing water tank 300 in this embodiment needs to be set higher than the preset high water level of the first heat exchange water tank 100. When the water level of the first heat exchange water tank 100 is reduced to a preset low water level, the low water level signal triggers the water replenishing electric valve 107 corresponding to the water replenishing tank 300 to be opened, and water is filled into the heat exchange water tank 100 through gravity; when the water level of the heat exchange water tank 100 rises to a preset high water level, the high water level signal triggers the water replenishing electric valve 107 corresponding to the water replenishing tank 300 to close, so that the water level of the heat exchange water tank 100 is controlled between the high water level and the low water level, and the heat exchanger 101 is ensured to take out the reactor core waste heat 72 hours after the accident shutdown.

The hot gas in the first gas cooling pipe 105 is used as an ascending section, the gas cooled in the first heat exchanger 101 enters the first descending cavity 103 to be used as a descending section, natural circulation flow is formed by the density difference and the potential difference of the cold gas and the hot gas, and the water vapor formed in the first heat exchange water tank 100 is discharged through the exhaust pipe at the top of the first heat exchange water tank, so that the residual heat in the reactor core is taken out by the system for a long time, and the wall surface of the pressure vessel 3 and the wall surface of the reactor cavity 4 are prevented from exceeding the preset temperature.

Similarly, the second annular gas cooler is located within the reactor chamber 4 and surrounds the pressure vessel 3. The second annular air cooler includes a second descending cavity 203, a plurality of second air cooling pipes 205, a second lower annular header 204, and a second upper annular header 206.

The second heat exchange means includes a second heat exchange water tank 200 and a second heat exchanger 201, the second heat exchange water tank 200 contains the supercooled water, and the second heat exchanger 201 is immersed in the supercooled water. The top of the second heat exchange water tank 200 is provided with an exhaust pipe, and when the supercooled water in the second heat exchange water tank 200 is heated to a saturated state, water vapor is generated and then discharged through the exhaust pipe.

The bottom of the second heat exchanger 201 in this embodiment is higher than the top of the second air-cooling pipe 205, so that the difference between the cold gas in the second heat exchanger 201 and the hot gas in the second air-cooling pipe 205 is increased, and the natural circulation flow is enhanced.

The outer wall surface of the second descending cavity 203 is fixedly arranged on the inner wall surface of the reactor chamber 4, the top of the second descending cavity 203 is communicated with the second heat exchanger 201 through the inlet electric valves 211 and 221 of the second annular air cooler, and the bottom of the second descending cavity 203 is communicated with the second lower annular header 204 through a pipeline.

Further, the second air-cooling pipes 205 are vertically arranged at equal intervals between the inner wall surface of the second descending cavity 203 and the outer wall surface of the pressure vessel 3, and are arranged in the circumferential direction.

The second air-cooling pipe 105 may be a pipe having a rectangular cross section, a pipe having a trapezoidal cross section, or a pipe having an inner arc-shaped cross section and an outer arc-shaped cross section, and the specific size may be set according to actual conditions. In this embodiment, a duct having a rectangular cross section is used, and the duct having a size of 10cm in length, 3cm in width, and 0.5cm in wall thickness, and the gap between every two adjacent second air-cooling pipes 105 is set to be 3 cm. The bottom of the second air-cooling tubes 205 is directly connected to the second lower annular header 204, the top of the second air-cooling tubes 205 is directly connected to the second upper annular header 206, and the second upper annular header 206 and the second heat exchanger 201 are connected via the outlet electrically operated valves 212, 222 of the second annular air-cooling tubes.

When the core heat in the pressure vessel 3 is radiated to the second air-cooling pipes 205 through the wall surface of the pressure vessel 3, the gas in the second air-cooling pipes 205 increases in temperature, increases in volume, and decreases in density, flows upward to the second heat exchanger 201, is cooled by the supercooled water in the second heat exchange water tank 200, and then flows back to the second air-cooling pipes 205 through the second downcomer cavity 203, and circulates back and forth. When the supercooled water in the second heat exchange water tank 200 is heated to a saturated state, water vapor is generated and then discharged through the exhaust pipe.

The water level of the replenishing water tank 300 in this embodiment needs to be set higher than the preset high water level of the second heat exchange water tank 200. When the water level of the second heat exchange water tank 200 is reduced to a preset low water level, the low water level signal triggers the water replenishing electric valve 207 corresponding to the water replenishing tank 300 to be opened, and water is filled into the heat exchange water tank 200 through gravity; when the water level of the heat exchange water tank 200 rises to the preset high water level, the high water level signal triggers the water replenishing electric valve 207 corresponding to the water replenishing tank 300 to close, so that the water level of the heat exchange water tank 200 is controlled between the high water level and the low water level, and the normal heat of the heat exchanger 201 is ensured.

The hot gas in the second gas cooling pipe 205 is used as an ascending section, the gas cooled in the second heat exchanger 201 enters the second descending cavity 203 to be used as a descending section, natural circulation flow is formed by the density difference and the potential difference of the cold gas and the hot gas, and the water vapor formed in the second heat exchange water tank 200 is exhausted through an exhaust pipe at the top of the second heat exchange water tank, so that the residual heat in the reactor core is taken out by the system for a long time, and the wall surface of the pressure vessel 3 and the wall surface of the reactor cavity 4 are prevented from exceeding the preset temperature.

Furthermore, the inner wall surface of the descending cavity is provided with a reflection heat insulation layer.

Further, the annular air cooler also comprises an annular support grid 5; the air-cooling pipes are fixed on the inner wall surface of the descending cavity through an annular support grid 5 and used for placing the air-cooling pipes.

Furthermore, the inner sides of the upper wall and the lower wall of the reactor cavity are both provided with a reflection heat insulation layer.

Further, the cross section of the air cooling pipe is circular, rectangular, trapezoidal or trapezoidal with inner and outer arcs.

Furthermore, an inlet electric valve, an outlet electric valve and a water replenishing electric valve of the annular air cooler are powered by a reliable power supply, so that the opening and closing of the system within 72 hours after the shutdown of the accident can be ensured.

The reliable power supply in the embodiment refers to reliable power supply measures such as a storage battery and the like, and the valve is supplied with power through the storage battery, so that the valve can be normally opened after the external power supply is lost.

In particular, the above embodiments, objects, technical solutions and advantages of the present invention are further described in detail, it should be understood that the above embodiments are only illustrative of the present invention and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.