CN106409362A - Single-tube experiment device for passive residual heat removal of molten salt reactors - Google Patents

Abstract

The invention provides a single-tube experimental device for exhausting passive waste heat from a molten salt reactor, which includes a tube-type vertical electric furnace, a heat exchange element, a steam drum, and a condenser; The temperature change of molten salt; the lower part of the heat exchange element is inserted into the tube vertical electric furnace, the upper part is connected with the steam drum, and the inlet and outlet of the heat exchange element are located inside the steam drum; the heat exchange element is a sheath type composed of two layers of casing The heat exchange element includes the outer casing, the middle casing and the central water inlet pipe. An annular passage for steam circulation is formed between the middle casing and the central water inlet pipe. The bottom of the central water inlet pipe communicates with the passage; the inlet of the condenser is connected to the The top of the steam drum is connected, and the outlet of the condenser is connected with the water inlet of the steam drum. The invention can be used for experimental research on the characteristics of the passive waste heat discharge system of the molten salt reactor, and has safe and reliable operation, reasonable design, simple operation and repeated use, and provides a platform for studying the characteristics of the passive waste heat discharge system of the molten salt reactor.

Description

A single-pipe experimental device for passive waste heat removal of molten salt reactor

technical field

The invention relates to an experimental device for waste heat discharge in the field of thermal hydraulics, in particular to a single-tube experimental device for passive waste heat discharge of molten salt reactors.

Background technique

The molten salt reactor is the only liquid fuel reactor among the six fourth-generation reactors. It is characterized by using liquid fusion of thorium or uranium dissolved in molten salts such as LiF and NaF as fuel, and does not need to make fuel assemblies. Compared with other reactor types, molten salt reactor has the advantages of strong negative reactivity, no need to add burnable poison, high fuel utilization rate and good safety, so it has attracted the attention of reactor researchers in various countries.

When the molten salt reactor is shut down, the system discharges the molten salt into the salt discharge tank. The passive waste heat discharge system of the molten salt reactor is mainly used to remove the waste heat of the molten salt in the salt discharge tank after the reactor shut down to prevent the molten salt from overheating. Due to the use of passive technology, the system can use the circulation of fluid to continuously export the heat generated by molten salt.

Chinese patent application No. 201310286718.7 discloses a passive waste heat removal system for molten salt reactors, including salt discharge tanks, heat exchange elements, steam drums, and air ducts. The upper part of the heat exchange elements is located in the steam drum. The lower part of the heat element is located in the salt discharge tank, and the rest of the heat exchange element is located between the steam drum and the salt discharge tank. The heat exchange element includes a heat transfer tube, and an intermediate sleeve is arranged in the heat transfer tube. The outer wall, the channel for steam circulation is formed between the inner wall and the outer wall, and the water inlet pipe is formed in the inner wall. The end of the air cooler is the inlet of the air cooler, the middle part is provided with finned tubes, and the steam drum and the inlet of the air cooler are connected. The system design scheme of the present invention can well solve the problem of passive waste heat discharge of the molten salt reactor theoretically, and is a better scheme. However, the system is only a theoretical design system, the actual operating characteristics cannot be determined, and it cannot be directly applied to engineering practice. Therefore, an experimental device more suitable for experimental research is needed to replace the system.

Contents of the invention

The purpose of the present invention is to provide a single-tube experimental device for passive waste heat discharge of molten salt reactors in order to complete the simulation experiment of passive waste heat discharge from molten salt reactors more safely and conveniently, and to obtain more accurate and credible experimental results.

The object of the present invention is achieved in the following way: comprising a tube type vertical electric furnace, a heat exchange element, a steam drum, a condenser, the lower part of the heat exchange element is inserted into the tube type vertical electric furnace, the upper part is connected with the steam drum, and the heat exchange The inlet and outlet of the components are located inside the steam drum, the inlet of the condenser is connected with the top of the steam drum, the outlet of the condenser is connected with the water inlet of the steam drum, and the top of the steam drum is also equipped with a safety valve and a pressure gauge, A pressure sensor is arranged on the side of the steam drum.

The present invention also includes such structural features:

1. The heat exchange element is a sheath-type heat exchange element composed of two layers of casing, which includes an outer casing, a middle casing and a central water inlet pipe. The middle casing and the central water inlet pipe are nested to form a An annular channel for steam circulation, the bottom of the central water inlet pipe communicates with the annular channel.

2. The pipeline between the outlet of the condenser and the water inlet of the steam drum is provided with a condensate measuring tube and a stop valve, and the pipeline communicates with the outside world through the exhaust valve.

3. A pressure sensor and a thermocouple are installed on the pipeline between the inlet of the condenser and the top of the steam drum.

Compared with the prior art, the beneficial effect of the present invention is that the present invention uses a tube-type vertical electric furnace to replace the molten salt tank, so there is no need to use dangerous molten salt for experiments, which increases the safety factor of experiments. The experimental device is simple in structure, easy to assemble, and convenient to operate. The condenser adopts water-cooling instead of air-cooling, which simplifies the experimental system and makes it easier to study the influence of condenser parameter changes on system operation. In a word, the present invention satisfies the experimental research requirements of the passive waste heat removal system of the molten salt reactor, has safe and reliable operation, reasonable design, simple structure and convenient operation, and is suitable for experimental research on the characteristics of the passive waste heat removal system of the molten salt reactor.

Description of drawings

Fig. 1 is a schematic diagram of the overall structure after assembly of the present invention;

Fig. 2 is a schematic structural diagram of a heat exchange element.

As shown in Figure 1, 1 is a tube-type vertical electric furnace, 2 is a sheath-type heat exchange element, 3 is a steam drum, 4 is a pressure gauge, 5 is a safety valve, 6 is a pressure sensor, 7 is a thermocouple, and 8 is condensation Device, 9 are condensate measuring tubes, 10 are shut-off valves, 11 are exhaust valves, and 12 are quick-fit joints.

As shown in Figure 2, 2-1 is the outer sleeve of the heat exchange element, 2-2 is the middle sleeve of the heat exchange element, 2-3 is the central tube of the heat exchange element, 2-4 is the outlet of the heat exchange element, 2-5 Inlet for the heat exchange element.

detailed description

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

As shown in Figure 1, the present invention discloses a single-tube experimental device for passive waste heat discharge of molten salt reactors, which mainly consists of the following parts: tube-type vertical electric furnace 1, heat exchange element 2, steam drum 3, safety Valve 5, condenser 8 and condensate measuring tube 9.

The tubular vertical electric furnace 1 is equivalent to the salt discharge tank in the molten salt reactor. It is the heat source of the system, and the heat generated by it is transferred to the heat-carrying medium water through the heat exchange element 2, and then the system circulates. Experiments at different temperatures can be performed by adjusting the temperature in the hearth of the tube-type vertical electric furnace 1 .

The heat exchange element 2 is a sheath-type casing structure, which includes an outer casing 2-1, a middle casing 2-2 and a central pipe 2-3. When the system is running, the water in the steam drum 3 enters the center pipe 2-3 through the inlet 2-5 of the heat exchange element, flows downward, turns back upwards after reaching the bottom, and enters a center pipe composed of the middle casing 2-2 and the center pipe. The annular channel formed by nesting of 2-3 flows upwards and is continuously heated during the flow process. Finally, the steam-water mixture in the annular channel enters the steam drum 3 through the outlet 2-4 of the heat exchange element to complete a small cycle. Armored thermocouples are installed at the inlet 2-5 and outlet 2-4 of the heat exchange element to measure the temperature at the inlet and outlet; welded on the outer wall of the outer casing 2-1 and the middle casing 2-2 There are thermocouples used to measure the temperature of the outer wall of the two layers of casing.

The steam drum 3 is a cylindrical structure, and the inlet 2-5 and the outlet 2-4 of the heat exchange element 2 are all in the steam drum 3, so the steam-water mixture is in the steam drum. A pressure gauge 4 is installed on the top of the steam drum 3 to monitor the pressure in the steam drum 3; a safety valve 5 is also installed on the top of the steam drum 3 to prevent the occurrence of an overpressure safety accident in the steam drum 3; The side upper part of 3 is equipped with pressure sensor 6, is used for real-time monitoring the change of pressure in steam drum.

The condenser 8 is a water-cooled condenser, and its condenser tube is an L-shaped heat exchange tube. The steam in the steam drum 3 enters the condenser 8 through the steam pipe to be condensed into water, and the heat is finally transferred to the water outside the condenser tube. An armored thermocouple 7 is respectively installed at the inlet and outlet of the condenser 8 to measure the temperature at the place, and then calculate the condensing power of the condenser; a pressure sensor 6 is also installed at the inlet of the condenser 8 to use To monitor the pressure at the inlet of the condenser 8 in real time.

The condensate measuring tube 9 is a circular glass tube with a scale, which can be used to measure the amount of condensed water in the condenser 8 during a period of time. When measuring, the shut-off valve 10 below the condensate measuring tube 9 will be closed.

The specific operation method of using this experimental device to carry out the experiment is as follows:

1. Preparatory work before the experiment: Prepare materials such as deionized water and tap water used in the experiment, and check whether the components of the experimental device are normal, especially whether the airtightness of the device is good.

2. Add deionized water to the steam drum 3, the liquid level should not exceed the outlet 2-5 of the heat exchange element, but not exceed the outlet 2-4 of the heat exchange element; add tap water to the condenser 8 to make the liquid level reach a certain height.

3. Set the parameters of the tube vertical electric furnace 1, set it to the temperature required for the experiment, and then start heating. When the temperature of the electric furnace reaches the set temperature and stabilizes, the exhaust valve 11 is opened to discharge the non-condensable gas in the system, and the exhaust valve 11 is closed after the non-condensable gas is exhausted, and the experimental measurement is carried out.

4. By adjusting different parameters such as the liquid level in the condenser 8, the liquid level in the steam drum 3, and the furnace temperature of the tube vertical electric furnace 1, the influence of these parameters on the system flow and heat transfer is studied.

5. After the experiment is completed, close the tube-type vertical electric furnace 1. After the system pressure drops to normal pressure, open the exhaust valve 11 to deflate the system to maintain the system at normal pressure and prevent the system from being in a vacuum state, which will affect the system. air tightness. After the system temperature dropped to room temperature, the experiment ended.

That is to say, the present invention is a single-tube experimental device for discharging passive waste heat from a molten salt reactor, including a tube-type vertical electric furnace, a heat exchange element, a steam drum, a condenser, and connecting pipelines; the tube-type vertical electric furnace is used for Simulate the temperature change of the molten salt in the molten salt stacking salt tank; the lower part of the heat exchange element is inserted into the tube vertical electric furnace, the upper part is connected to the steam drum, and the inlet and outlet of the heat exchange element are located inside the steam drum; the heat exchange element is a A sheath-type heat exchange element composed of two layers of sleeves, including an outer sleeve, a middle sleeve and a central water inlet pipe. An annular channel for steam circulation is formed between the middle sleeve and the central water inlet pipe. The bottom of the central water inlet pipe is connected to the The channel is connected; the inlet of the condenser is connected with the top of the steam drum, and the outlet of the condenser is connected with the water inlet of the steam drum. The molten salt reactor passive waste heat discharge single-pipe experimental device also includes an overpressure protection device, which is used to prevent safety accidents due to excessive pressure during system operation. The function of the protection device is mainly realized by a safety valve. The safety valve Set on top of steam drum. The heat exchange element, steam drum, and condenser components are all provided with temperature sensing components on the surface or inside to monitor the temperature change of each part in the system. The present invention also includes a condensate measuring device, which is arranged at the lower part of the outlet of the condenser, and is used for collecting condensed water condensed through the condenser. The invention also includes pressure transducers and pressure gauges for measuring pressure in the system. The invention also includes an exhaust valve for removing non-condensable gases from the system.

Claims (5)

1. a kind of single tube experimental provision for MSR passive residual heat removal it is characterised in that：Including the vertical electric furnace of tubular type, Heat exchange element, drum, condenser, in the vertical electric furnace of described heat exchange element side bottom inserting pipe-type, top is connected with drum, and changes The import and export of thermal element are all located inside steam drum, and the entrance of condenser is connected with the top of drum, the outlet of condenser and vapour The water inlet of bag is connected, and the top of described drum is additionally provided with relief valve and the side of pressure gauge, drum is provided with pressure biography Sensor.

2. a kind of single tube experimental provision for MSR passive residual heat removal according to claim 1, its feature exists In：Described heat exchange element is a sheath heat exchange element being made up of two-layer sleeve pipe, it include outer layer sleeve, intermediate casing and in Heart water inlet pipe, is nested to form a circular passage supplying steam circulation, center water inlet pipe between intermediate casing and center water inlet pipe Bottom is connected with this circular passage.

3. a kind of single tube experimental provision for MSR passive residual heat removal according to claim 1 and 2, its feature It is：Lime set measurement pipe and stop valve and this pipeline are provided with the pipeline between the outlet of condenser and the water inlet of drum Communicated with the external world by air bleeding valve.

4. a kind of single tube experimental provision for MSR passive residual heat removal according to claim 1 and 2, its feature It is：Pressure transducer and thermocouple are provided with the pipeline between the entrance of condenser and the top of drum.

5. a kind of single tube experimental provision for MSR passive residual heat removal according to claim 3, its feature exists In：Pressure transducer and thermocouple are provided with the pipeline between the entrance of condenser and the top of drum.