阅读说明：本技术 一种用于熔盐堆的余热导出装置及其导出方法 (Waste heat exporting device and method for molten salt reactor ) 是由 吴祥成 卢金 于 2020-12-23 设计创作，主要内容包括：本发明提供一种用于熔盐堆的余热导出装置及其导出方法,该装置包括放置在排盐罐内的传热管,排盐罐与熔盐下泄管线连接,传热管的进入端通过下泄管线与蒸汽冷凝器的出口连接,传热管的排出端通过上升管线与蒸汽冷凝器的入口连接,蒸汽冷凝器设置在冷却池中,下泄管线与充液管连接,充液管上设有充液阀。该装置和方法利用膜态沸腾传热技术代替核态沸腾传热,实现熔盐堆非能动余热排出系统的优化,提供一套安全稳定的余热排出系统。(The invention provides a waste heat deriving device for a molten salt reactor and a deriving method thereof. The device and the method utilize a film state boiling heat transfer technology to replace a nuclear state boiling heat transfer technology, realize the optimization of the molten salt reactor passive residual heat removal system, and provide a set of safe and stable residual heat removal system.)

1. The utility model provides a waste heat eduction gear for fused salt heap, a serial communication port, including placing heat-transfer pipe (2) in row salt jar (1), arrange salt jar (1) and fused salt and let off pipeline (3) and be connected down, the entry end of heat-transfer pipe (2) is through letting off pipeline (4) and steam condenser (5) exit linkage down, the discharge end of heat-transfer pipe (2) is through rising pipeline (6) and steam condenser's (5) entry linkage, steam condenser (5) set up in cooling tank (7), let off pipeline (4) and liquid filling pipe (8) be connected down, be equipped with prefill valve (9) on liquid filling pipe (8).

2. The residual heat removal device for the molten salt reactor according to claim 1, wherein the liquid filling pipe (8) is connected with a voltage stabilizer (10), a safety valve (11) is arranged at the upper part of the voltage stabilizer (10), the liquid filling pipe (8) is connected with a branch pipe (12), and a water replenishing valve (13) is arranged on the branch pipe (12).

3. The residual heat removal device for the molten salt reactor according to claim 1, wherein a vacuum system interface (14) is arranged on the ascending pipeline (6), and a suction valve (15) is arranged on the vacuum system interface (14).

4. The residual heat removal device for a molten salt reactor according to claim 1, characterized in that the heat transfer pipe (2) is a "U" -shaped pipe.

5. The waste heat removal device for the molten salt reactor according to claim 4, wherein the number of the heat transfer pipes (2) is multiple, the inlet ends of the heat transfer pipes (2) are connected with the lower drain pipeline (4) through a lower drain distributor, the lower drain distributor comprises a liquid storage tank (16), the top of the liquid storage tank (16) is connected with the lower drain pipeline (4), the liquid storage tank (16) is connected with the heat transfer pipes (2) through a connecting joint (17), a control valve (18) is arranged on the connecting joint (17), the outlet ends of the heat transfer pipes (2) are connected with an ascending steam collector, the ascending steam collector comprises a collecting tank (19), the top of the collecting tank (19) is connected with the ascending pipeline (6), and the lower side of the collecting tank is provided with a plurality of collecting joints (20) connected with the heat transfer pipes (2).

6. The residual heat removal device for the molten salt reactor as claimed in claim 5, characterized in that the connecting joint (17) is arranged at the top of the liquid storage tank (16), a liquid discharge pipe (21) is arranged at the bottom of the liquid storage tank (16), and a liquid discharge valve (22) is arranged on the liquid discharge pipe (21).

7. The residual heat removal device for a molten salt reactor according to claim 1, characterized in that a partition plate (23) is arranged in the salt discharge tank (1).

8. The residual heat removal device for a molten salt reactor according to claim 1, characterized in that the connection end of the heat transfer pipe (2) and the salt discharge tank (1) is provided with a plurality of expansion joints (24).

9. The residual heat removal device for a molten salt reactor according to claim 1, characterized in that a second safety valve (25) is provided on the ascending pipeline (6).

10. A residual heat deriving method for a molten salt reactor is characterized by comprising the following steps:

step one, opening an air extraction valve (15) on a vacuum system interface (14), and closing the air extraction valve (15) after exhausting impurity gas in a pipeline;

secondly, discharging the high-temperature molten salt into a salt discharging tank (1) through a molten salt discharging pipeline (3), opening a liquid filling valve (9), and enabling cooling water to enter a heat transfer pipe (2);

step three, cooling water enters the heat transfer pipe (2) to generate film boiling heat transfer, the cooling water is changed into steam from a liquid phase, the steam enters the steam condenser (5) through the ascending pipeline (6) to be condensed, and condensate liquid flows back to the lower drainage pipeline (4) to complete circulation establishment;

step four, after the molten salt is drained, gradually closing a control valve (18) on the connecting joint (17), and reducing the number of the heat transfer pipes (2) to be put into use until the heat transfer pipes are completely closed;

and step five, opening a liquid discharge valve (22) to empty the liquid storage tank (16), and opening an air suction valve (15) to enable the system to enter a cold standby state.

Technical Field

The invention relates to the field of reactor thermal hydraulic power, in particular to a waste heat deriving device for a molten salt reactor and a deriving method thereof.

Background

As an important development of the future fourth generation reactors, the molten salt reactor is the only liquid fuel reactor. The molten salt is a eutectic with low melting point formed by combining some fluoride of uranium, thorium or plutonium which are easy-to-fission and fertile materials with carrier salt, and is in a very stable liquid phase at the temperature of more than 500 ℃ under normal pressure. The inlet and outlet temperature of the reactor core under the normal operation working condition is 550-800 ℃. Compared with other reactor types, the molten salt reactor has the advantages of large negative reaction temperature coefficient and cavity coefficient, high energy density, normal pressure operation and high temperature output, so the molten salt reactor is concerned by reactor researchers in various countries.

The united states oak ridge laboratory (ORNL) completed the design and construction of a 10MW molten salt heap in the last 60 th century. The experimental reactor runs for more than 10000 hours, and the feasibility of the molten salt reactor is successfully verified.

After the molten salt reactor is shut down, the freezing valve is opened, and the liquid molten salt is discharged into the salt discharge tank under the action of gravity, so that the residual heat discharge process of the molten salt reactor is generally carried out around the salt discharge tank. In the ORNL experimental stack waste heat discharge system, a cooling water pump is adopted by ORNL to drive cooling water to flow through a waste heat exchanger, decay heat is brought out to a cooling tower for cooling, and the system cannot eliminate the possibility of failure of a pump body although a backup cooling water pump is arranged.

CN103400608B discloses a fused salt waste heat eduction gear based on nested tubular construction, and the heat transfer component that the device adopted contains two-layer sleeve pipe, is the air gap layer between outer tube and the endotheca pipe. The existence of the air gap layer enables the flowing heat exchange in the sleeve to fall in a nucleate boiling zone. The cold end of the system adopts an air duct device, and the condenser directly transfers heat to outside air. Compared with the active cooling device adopted by ORNL, the patent eliminates a system pump, and completely drives the whole flowing heat transfer process by passive natural circulation, so that the reliability is further improved. This device has some drawbacks. Firstly, the sleeve device has a complex structure, and an air gap layer is added for weakening nucleate boiling heat transfer; secondly, the air cooling device is obviously influenced by the weather conditions and the weather conditions, and is not beneficial to the stable operation of the whole system.

Disclosure of Invention

The invention aims to solve the technical problem of providing a residual heat deriving device for a molten salt reactor and a deriving method thereof, which utilize a film boiling heat transfer technology to replace a nuclear boiling heat transfer technology, realize the optimization of a passive residual heat discharging system of the molten salt reactor, and provide a set of safe and stable residual heat discharging system.

In order to solve the technical problem, the invention adopts the technical scheme that the waste heat guide device for the molten salt reactor comprises a heat transfer pipe arranged in a salt discharge tank, the salt discharge tank is connected with a molten salt discharging pipeline, the inlet end of the heat transfer pipe is connected with the outlet of a steam condenser through the discharging pipeline, the outlet end of the heat transfer pipe is connected with the inlet of the steam condenser through an ascending pipeline, the steam condenser is arranged in a cooling pool, the discharging pipeline is connected with a liquid filling pipe, and a liquid filling valve is arranged on the liquid filling pipe.

In the preferred scheme, the liquid filling pipe is connected with the pressure stabilizer, the upper part of the pressure stabilizer is provided with a safety valve, the liquid filling pipe is connected with a branch pipe, and the branch pipe is provided with a water replenishing valve.

In a preferred scheme, a vacuum system interface is arranged on the ascending pipeline, and an air extraction valve is arranged on the vacuum system interface.

In a preferred embodiment, the heat transfer pipe is a "U" pipe.

In a preferable scheme, the number of the heat transfer pipes is multiple, the inlet ends of the heat transfer pipes are connected with a downward drainage pipeline through a downward drainage distributor, the downward drainage distributor comprises a liquid storage tank, the top of the liquid storage tank is connected with the downward drainage pipeline, the liquid storage tank is connected with the heat transfer pipes through a connecting joint, a control valve is arranged on the connecting joint, the outlet ends of the heat transfer pipes are connected with an ascending steam collector, the ascending steam collector comprises a collecting tank, the top of the collecting tank is connected with the ascending pipeline, and a plurality of collecting joints connected with the heat transfer pipes are arranged on the lower side of the collecting tank.

In the preferred scheme, the connecting joint is arranged at the top of the liquid storage tank, the bottom of the liquid storage tank is provided with a liquid discharge pipe, and the liquid discharge pipe is provided with a liquid discharge valve.

In a preferable scheme, a partition plate is arranged in the salt discharging tank.

In a preferable scheme, a plurality of expansion joints are arranged at the connecting end of the heat transfer pipe and the salt discharge tank.

In a preferred scheme, a second safety valve is arranged on the ascending pipeline.

The invention also provides a residual heat deriving method for the molten salt reactor, which comprises the following steps:

step one, opening an air extraction valve on a vacuum system interface, and closing the air extraction valve after exhausting impurity gas in a pipeline;

step two, discharging the high-temperature molten salt into a salt discharge tank through a molten salt discharge pipeline, opening a liquid filling valve, and enabling cooling water to enter a heat transfer pipe;

step three, cooling water enters the heat transfer pipe to generate film boiling heat transfer, the cooling water is changed into steam from a liquid phase, the steam enters the steam condenser through the ascending pipeline to be condensed, condensate liquid flows back to the descending pipeline, and circulation establishment is completed;

after the molten salt is drained, gradually closing a control valve on the connecting joint, and reducing the number of the heat transfer pipes to be put into use until the heat transfer pipes are completely closed;

and step five, opening a liquid discharge valve to empty the liquid storage tank, and opening an air suction valve to enable the system to enter a cold standby state.

The invention provides a waste heat exporting device and a method for a molten salt reactor, which have the following beneficial effects:

1. the heat transfer pipe is a single-layer wall surface, and the heat transfer mode is not nucleate boiling any more and is changed into film boiling. The structure of the heat transfer pipe is greatly simplified, and the reliability of the heat transfer element is improved.

2. The liquid level height in the voltage stabilizer and the cooling pool is mutually matched and adjusted, and the reliable and stable operation of the system can be effectively realized.

3. The system is a passive natural circulation system, runs without a pump, and eliminates potential safety hazards caused by failure of a pump body.

4. Compared with an air cooling scheme, the method for providing the final heat trap by the cooling pool can greatly reduce the volume of the cold source part and has good heat transfer stability.

5. The heat transfer controllability and the thermal stress controllability are high. Whether any heat transfer pipe is used or not can be controlled by a valve on the flow distributor of the downward drainage pipeline.

6. The expansion joint design of the heat transfer pipe can effectively relieve local thermal stress; the surrounding descending of the fused salt downward-discharging pipeline also reduces the pipeline stress caused by the inflow of the fused salt.

7. The safety valve at the top of the pressure stabilizer and the safety valve at the top of the steam ascending pipeline can both complete the purpose of emergency pressure relief, and the safety of the system is further improved.

Drawings

The invention is further illustrated with reference to the accompanying drawings and examples:

FIG. 1 is a schematic view of the overall structure of the present invention;

FIG. 2 is an enlarged view taken at A in FIG. 1;

FIG. 3 is a schematic view of the structure of the lower bleed distributor;

FIG. 4 is a schematic diagram of the construction of an ascending vapor concentrator;

FIG. 5 is a graph of pressure change after the system has been put into operation;

in the figure: the system comprises a salt discharge tank 1, a heat transfer pipe 2, a molten salt discharge pipeline 3, a discharge pipeline 4, a steam condenser 5, an ascending pipeline 6, a cooling pool 7, a liquid filling pipe 8, a liquid filling valve 9, a pressure stabilizer 10, a safety valve 11, a branch pipe 12, a water replenishing valve 13, a vacuum system interface 14, an air suction valve 15, a liquid storage tank 16, a connecting joint 17, a control valve 18, a collecting tank 19, a collecting joint 20, a liquid discharge pipe 21, a liquid discharge valve 22, a partition plate 23, an expansion joint 24 and a second safety valve 25.

Detailed Description

As shown in figure 1, a waste heat eduction gear for fused salt heap, including placing the heat-transfer pipe 2 in arranging salt jar 1, in this embodiment, heat-transfer pipe 2 is "U" venturi tube, arranges salt jar 1 and fused salt and lets out pipeline 3 and be connected down, and fused salt lets out pipeline 3 down, and the expansion valve of reactor vessel lower part is connected, and fused salt lets out pipeline 3 down and adopts the surrounding type to arrange, can effectively avoid fused salt to let out the expansion stress that high temperature fused salt caused in the pipeline 3 down. The inlet end of the heat transfer pipe 2 is connected with the outlet of the steam condenser 5 through a downward discharge pipeline 4, the outlet end of the heat transfer pipe 2 is connected with the inlet of the steam condenser 5 through an upward pipeline 6, the steam condenser 5 is arranged in a cooling pool 7, the downward discharge pipeline 4 is connected with a liquid filling pipe 8, and the liquid filling pipe 8 is provided with a liquid filling valve 9.

Preferably, as shown in fig. 3 and 4, the number of the heat transfer pipes 2 is multiple, a parallel pipe bundle is adopted, the inlet ends of the heat transfer pipes 2 are connected with the lower drain pipe 4 through a lower drain distributor, the lower drain distributor comprises a liquid storage tank 16, the top of the liquid storage tank 16 is connected with the lower drain pipe 4, the liquid storage tank 16 is connected with the heat transfer pipes 2 through a connecting joint 17, specifically, the connecting joint 17 is connected with the heat transfer pipes 2 through flanges, a control valve 18 is arranged on the connecting joint 17, the outlet ends of the heat transfer pipes 2 are connected with an ascending steam collector, the ascending steam collector comprises a collecting tank 19, the top of the collecting tank 19 is connected with the ascending pipe 6, and a plurality of collecting joints 20 connected with the heat transfer pipes 2 are arranged on.

By arranging a plurality of heat transfer pipes 2 in parallel, on one hand, the cooling efficiency of the salt discharging tank is improved, and on the other hand, the heat transfer controllability and the thermal stress controllability are high. Whether any heat transfer pipe 2 is used or not can be controlled by the control valve 18.

Preferably, the connection joint 17 is arranged at the top of the liquid storage tank 16, the bottom of the liquid storage tank 16 is provided with a liquid discharge pipe 21, and the liquid discharge pipe 21 is provided with a liquid discharge valve 22.

The connecting joint 17 is arranged at the top of the liquid storage tank 16, so that the liquid storage tank 16 can overflow from the connecting joint 17 to the heat transfer pipe 2 after being filled with the liquid, and accumulated liquid in the liquid storage tank 16 can be discharged through the liquid discharge pipe 21 after cooling is completed, so that the amount of accumulated liquid generated in the heat transfer pipe 2 can be reduced.

Preferably, a partition plate 23 is arranged in the salt discharging tank 1. Specifically, the inner wall of the salt discharging tank 1 may be provided with a mounting groove matched with the partition plate 23. The partition plate 23 partitions the salt discharge tank 1 into two sides, and the heat transfer pipe 2 passes through the partition plate 23 so that the downcomer 4 and the upcomer 6 are respectively disposed on the two sides of the partition plate 23. The connecting position of the fused salt downward drainage pipeline 3 and the salt discharge tank 1 is arranged on one side of the connecting ascending pipeline 6, and the connecting position of the fused salt downward drainage pipeline 3 and the salt discharge tank 1 is lower than the height of the partition plate 23.

The salt discharging tank 1 is divided into two parts by arranging the partition plate 23, so that the fused salt overflows to the other side after the liquid level of one side is higher than the height of the partition plate 23, the violently generated steam rises along the heat transfer pipe 2 to be collected in the steam collector and then flows into the ascending pipeline 6, and a natural circulation process is established because the density difference exists between the steam in the ascending pipeline 6 and the cooling water in the downward discharging pipeline 4.

Preferably, as shown in fig. 2, the connection end of the heat transfer pipe 2 and the salt discharging tank 1 is provided with a plurality of expansion joints 24.

The expansion joint 24 is arranged to effectively relieve local thermal stress.

Preferably, the liquid charging pipe 8 is connected with a pressure stabilizer 10, a safety valve 11 is arranged at the upper part of the pressure stabilizer 10, the liquid charging pipe 8 is connected with a branch pipe 12, and a water replenishing valve 13 is arranged on the branch pipe 12.

Through setting up stabiliser 10, can mutually support the regulation with liquid level height in the cooling bath 7, can effectively realize the reliable steady operation of system.

The ascending pipeline 6 is provided with a vacuum system interface 14, and the vacuum system interface 14 is provided with an air extraction valve 15.

When the vacuum system is used, the vacuum system interface 14 is connected with a vacuum pumping device through a pipeline, the pipeline of the whole system is vacuumized through the opening and closing of the air pumping valve 15, and impurity gas in the pipeline can be discharged.

In a preferred embodiment, a second safety valve 25 is provided on the ascending pipe 6.

The purpose of emergency pressure relief can be realized by arranging the second safety valve 25, and the operation safety of the system is improved.

A method for deriving residual heat of a molten salt reactor comprises the following steps:

step one, opening a gas extraction valve 15 on a vacuum system interface 14, and closing the gas extraction valve 15 after discharging impurity gas in a pipeline.

And step two, after the molten salt reactor is shut down, discharging high-temperature molten salt at the temperature of 600 ℃ into a salt discharge tank 1 through a molten salt discharging pipeline 3, opening a liquid filling valve 9 after partial heat exchange tubes are submerged in the molten salt in the salt discharge tank, enabling cooling water to enter a heat transfer tube 2, enabling the molten salt to firstly flow into the right space of a partition plate 23, and enabling the molten salt to flow into the left space of the salt discharge tank 1 again after the molten salt liquid level in the right space in the salt discharge tank 1 is higher than the partition plate 23.

And step three, cooling water enters the heat transfer pipe 2, and because the temperature of the right side wall surface of the heat transfer pipe 2 is close to the temperature of the molten salt but the temperature of the left side wall surface is not raised soon after the molten salt just enters the space on the right side of the salt discharge tank 1 at the moment, film boiling heat transfer can occur after the cooling water flows to the right side of the heat transfer pipe 2. The cooling water changes from liquid phase to steam, and the steam produced violently rises along the heat transfer pipe 2 to the collection tank 19 and then enters the rising line 6. Due to the difference in density of the steam in the uptake line 6 and the cooling water in the letdown line 4, a natural circulation process is established.

Cooling water is changed from liquid phase to steam and enters a steam condenser 5 for condensation through an ascending pipeline 6, condensate liquid flows back to a discharging pipeline 4, and closed circulation of cooling liquid, steam and cooling liquid is completed. Latent heat of vaporization in the steam condenser 5 is conducted to the cooling pool 7 through the wall of the condenser pipe and the nucleate boiling heat transfer outside the condenser.

And step four, after the molten salt is discharged, the molten salt liquid level in the salt discharging tank 1 is higher than the partition plate 23, and the established natural circulation process is continuously maintained due to the flowing inertia of the cooling water, so that the heat is stably transferred. And after the pressure in the system reaches a preset value, closing the liquid filling valve 9.

Along with the gradual decline of fused salt decay heat, the outward output heat of system also can reduce gradually, and fused salt temperature, heat-transfer pipe wall temperature also can descend simultaneously. At this time, the film boiling exhibits a certain self-regulation property. The magnitude of the film boiling heat transfer quantity is greatly related to the convective heat transfer intensity in the gas film and the radiation heat transfer intensity in the gas film, and the general trend is that the heat flow density of the film boiling heat transfer is reduced along with the reduction of the wall temperature of the heat transfer pipe, which is adapted to the reduction of the decay heat of the molten salt. Thus, the system enhances its power regulation capability due to the heat transfer characteristics of film boiling.

When the self-adjusting capacity of the system cannot be adapted to decay heat, the control valve 18 of the connection joint 17 is connected to the closing portion to reduce the number of heat transfer pipes for step adjustment, and the number of heat transfer pipes 2 to be put into use is reduced until the heat transfer pipes are completely closed.

The liquid level of the cooling pool 7 can be actively reduced to realize continuous adjustment, so that a part of condensing pipes of the steam condenser 5 are exposed to the air, and the condensing area can be finely adjusted to realize accurate matching of decay heat and system output heat. When the liquid level of the cooling pool 7 is adjusted, the water replenishing valve 13 at the lower part of the corresponding adjusting voltage stabilizer can realize the constant pressure in the system.

And step five, opening the liquid discharge valve 22 to empty the liquid storage tank 16, and opening the air suction valve 15 to enable the system to enter a cold standby state.

The calculation simulation of tens of hours shows that the system operating pressure under film boiling does not exceed 2Mpa as shown in fig. 5. The later decay power is gradually reduced, and the system pressure is synchronously reduced.