JPS6283001A - Liquid metal purification device - Google Patents

Abstract

PURPOSE:To make the device smaller and more compact by accommodating the magnetic pump, the magnetic flow meter, the heat exchanger, the cold trap and the pipings to connect the said equipments of the liquid metal purification device into a single vessel. CONSTITUTION:The pipings 5, the magnetic pump cooling line 6, the cold trap cooling line 7 and the cable 8 are accommodated in one vessel 22; the cold trap 4 is located in the upper part, the magnetic pump 1 is installed in the lower part, and the heat exchanger 25 is installed between the said two equipments. The high-temperature liquid metal sucked with the magnetic pump 1 through the liquid metal suction nozzle 28, after being precooled by the low- temperature liquid metal purified with the heat exchanger 25, flows into the cold trap 4. The liquid metal purified by the cold trap 4, after being heated up with the high-temperature liquid metal which is not yet purified with the heat exchanger 25, is flowed back to the nuclear reactor through the liquid metal nozzle 29.

Description

[Detailed description of the invention] [Field of application of the invention] The present invention relates to a liquid metal purification device, particularly an electromagnetic pump.

This invention relates to a liquid metal purification device having an electromagnetic flow system, a heat exchanger, and a cold trap.

[Background of the invention]

A cold trap, which is the most commonly used device for continuously purifying liquid metal, utilizes the fact that impurities contained in liquid metal precipitate out when the temperature of the liquid metal is lowered. FIG. 4 shows a conventional general liquid metal purification system (hereinafter referred to as a purification system) using a cold trap.

This purification system includes an electromagnetic pump 1, an electromagnetic flowmeter 2. Heat exchanger 3. Cold trap 4. Piping that connects them 5. Electromagnetic pump cooling system 6, cold trap cooling system 7. Consists of various cables 8.

In the purification system configured in this way, the electromagnetic pump 1
The high temperature liquid metal pumped up from the main system 9 is precooled by the purified low temperature liquid metal in the heat exchanger 3, and then flows into the cold trap 48. The liquid metal in the cold trap 4 is cooled by the cold trap cooling system 7, precipitated impurities are removed by the wire mesh 10, and then heated by the high temperature liquid metal before purification in the heat exchanger 3 and sent to the main system. Returned to 11.

The operating principle of the cold trap will be explained using FIG. In Figure 5, temperature and solubility are plotted on the horizontal and vertical axes, respectively, and the saturation solubility curve 1 of impurities contained in liquid metals.
2 qualitatively.

As shown in this figure, the amount of impurities that can dissolve in the liquid metal increases as the temperature increases, therefore, the temperature To
, when an unsaturated liquid metal with solubility Co is cooled to temperature T2, the saturated solubility becomes G.

At the temperature Tl where (=Cx), excess impurities that can no longer be dissolved in the liquid metal begin to precipitate as a solid. Then, in the state cooled to temperature Tz, ΔC=G
An amount of impurities corresponding to o-C2 will be precipitated.

Figure 6 shows a specific example of the purification system explained using Figures 4 and 5. The same parts as in Figure 4 are given the same reference numerals, and 13 indicates the reactor vessel. , 14 and surrounded by the dashed line corresponds to the purified system in FIG. In this example, the purification system is provided as an auxiliary system branched from the main system around the reactor vessel 13, and the electromagnetic pump 1, electromagnetic flow meter 2, heat exchanger 3, cold trap 4, cold trap cooling system 7, etc. are separated. The pipes 5 are connected by a pipe 5.

By the way, such a distributed purification system is useful when purifying coolant in a large plant such as a fast breeder reactor that uses liquid metal as a coolant in a nuclear reactor.
There are the following problems.

(1) Increase in equipment Because piping is branched off from the main system and routed to the room where the purification equipment is installed, the amount of piping and associated equipment is enormous. Furthermore, a large amount of piping and auxiliary equipment between the main components of the purification system, as well as auxiliary equipment for installing the main equipment, is required.

(2) Increase in installation space and building More space is required for installation, and as a result, the building becomes larger.

(3) Conflict with design ideals In particular, in nuclear reactors such as tank reactors, which are characterized by confining the primary coolant within the reactor vessel, there is a need for branches that take the trouble of transporting the confined coolant outside the reactor. Type purification strains are not preferred.

In the design research of tank-type fast breeder reactors currently underway in various countries, studies are already underway to downsize nuclear reactors. There are high expectations for this. In this sense, miniaturization of purification equipment, which is one of the in-furnace equipment, is also attracting attention as an important issue.

[Purpose of the invention]

An object of the present invention is to provide a more compact liquid metal purification apparatus that can improve the purification capacity in the same space, or conversely maintain the purification capacity.

[Summary of the invention]

The present invention is an electromagnetic pump that circulates liquid metal.

11 for measuring the liquid metal flow m! A liquid metal purification apparatus having a magnetic flowmeter, a heat exchanger for precooling the liquid metal, and a cold trap for removing impurities in the liquid metal, the electromagnetic pump, the electromagnetic flowmeter, the heat exchanger, and a cold trap for removing impurities in the liquid metal. The exchanger, the cold trap, and the piping connecting these are empty, and at least one component other than the 111f heat exchanger, the piping, and the cable are arranged in the hollow center. That is.

The present invention was made based on the results of studies on miniaturization of liquid metal purification devices, and the results of the studies will be explained below.

In other words, when downsizing, the equipment shown in Figure 4, the piping that connects them, the attached equipment, and the cables are housed in one container to form a single purification unit that contains liquid metal. One possible method is to install it inside the main container. However, in such cases, the shape and dimensions of the purification unit container itself are often restricted due to dimensional conditions on the main container side, and space constraints for each device installed in the container become severe. For example, when a unit-type device is used as a primary coolant purification device for a tank-type fast breeder reactor, its arrangement is considered to be as shown in FIG. In this figure, 13 is the reactor vessel.

15 is a large rotary plug, 16 is a primary main circulation pump, 17 is a main intermediate heat converter, and 18 is a liquid metal purification device (hereinafter referred to as a purification device). That is, the reactor vessel 13
A purification unit 18 is inserted between the primary main circulation pump 16 and the main intermediate heat exchanger 17, which are arranged concentrically between the large-rotation plug 15 and the main intermediate heat exchanger 17. Therefore, the diameter of the reactor vessel 13 depends on both the diameter of the large rotating plug 15 and the diameter of each reactor equipment such as the primary main circulation pump 16, the main intermediate heat exchanger 17, and the purification device 18. In order to reduce the size of the reactor, it is necessary to reduce the diameter of the large rotating plug 15 as well as the diameter of each furnace equipment. The reason for this will be explained using FIG. 8.

Figure 8 is a characteristic diagram in which the horizontal axis is the diameter of the large-rotation plug, the vertical axis is the reactor vessel diameter, and the diameter of typical reactor equipment (for example, purification bag VT18) is drawn as a parameter, and 19 is the purification device. 20 indicates a case where the in-furnace equipment such as a purification device is small. As is clear from this figure, in region B where the diameter of the large-rotary plug is large to some extent, the determining factor for the diameter of the reactor vessel is the diameter of the large-rotary plug, and the miniaturization of the large-rotation plug has a direct effect on the miniaturization of the reactor vessel. However, in region A where the diameter of the large-rotation plug becomes sufficiently small, this effect is saturated, and the diameter of the reactor vessel is rather influenced by the diameter of each in-reactor equipment installed around the large-rotation plug. Therefore, in order to miniaturize the reactor in this area, it is necessary to reduce the diameter of each in-reactor equipment.Therefore, when designing a unit type purification device, As shown in Figure 4, it is necessary to devise effective measures for the shapes and dimensions of the various equipment necessary for the purification system, the piping and cables that connect them, and the way they are arranged within the purification equipment container.

For this reason, the present invention uses a heat exchanger that has a double shell consisting of an inner cylinder and an outer cylinder, and has a hollow central part, and uses the hollow central part as a passage for piping or cables, and other than the heat exchanger. This achieved the intended purpose by making it possible to reduce the size in the radial direction by using it as a space for arranging equipment.

[Embodiments of the invention] Examples will be described below.

1, 2, and 3 are explanatory diagrams of a primary coolant purification device for a tank-type fast breeder reactor according to an embodiment, and FIG. 1 is an explanatory diagram of the structure of a unit-type purification device; Figure 2 is a perspective view showing details of the structure of the heat exchanger in Figure 1, and Figure 3 is an explanatory diagram of the reactor structure of a tank-type fast breeder reactor using the unit-type water deionizer shown in Figure 1. It is. In these figures, 4th. The same parts as in FIGS. 6 and 7 are given the same reference numerals. and.

transformation In these figures, 21 is a unit type water purifier.

22 is a container of the purification device 2I, 23 is a heat insulating structure provided on the inner periphery of the container 22, 24 is a radiation shielding structure provided on the outer periphery of the electromagnetic pump 1, and 25 is a heat exchanger with a hollow center. 26 is a shell inner cylinder of the heat exchanger 25, 2
7 is also a shell outer cylinder, 28 is a liquid metal suction nozzle, 2
9 is a liquid metal discharge nozzle, 30 is a reactor core, and 31 is a core support structure.

It shows.

As shown in FIG. 3, a reactor core 30 is provided in the center of the reactor vessel 13, and is fixed to the reactor vessel 13 via a core support structure 31. A primary main circulation pump 16 and a main intermediate heat exchanger 7 are arranged near the side wall inside the reactor vessel 13. Connected to the bottom. Further, the main intermediate heat exchanger 17 is connected to the core 30 through a hot plenum 33 formed in the upper part of the core 30.
The lower end of the main intermediate heat exchanger 17 opens toward a cold plenum 34 formed at the bottom of the reactor vessel 13. Refrigerant purification'jflv't2
1 is suspended from the roof slab 35 between the diameters of these reactor vessels and immersed in the hot plenum 33.

In a nuclear reactor configured in this manner, the primary coolant heated in the reactor core 30 enters the hot plenum 33 and then enters the main intermediate heat exchanger 17.

The primary coolant cooled by the secondary coolant in the three main intermediate heat exchangers 17 is sent to the core 30 from the high pressure plenum 32 again by the primary main circulation pump 16 via the cold plenum 34. .

Further, a part of the primary coolant circulating in this manner is sucked from the hot plenum 33 to the purification device 21, and after impurities are removed, it is returned to the hot plenum 33 again.

Next, the structure of the purification device 21 installed in the reactor vessel 13 in this manner will be explained with reference to FIG. This purification device 21 includes an electromagnetic pump 1, an electromagnetic flowmeter 2. heat exchanger 2
5. Cold trap 4, piping 5 connecting them, electromagnetic pump cooling system 6, cold trap cooling system 7. Various cables 8 are housed in one container 22, and a cold trap 4. An electromagnetic pump 1 is installed at the bottom, and a heat exchanger 25 is installed in the middle.

In the unit-type purification device configured in this manner, the high-temperature liquid metal sucked by the electromagnetic pump 1 through the liquid metal suction nozzle 28 is precooled by the purified low-temperature liquid metal in the heat exchanger 25, and then precooled by the purified low-temperature liquid metal. cold trap 4
flow into. The liquid metal purified in the cold trap 4 is heated by the high-temperature liquid metal before purification in the heat exchanger 25, and then transferred to the reactor vessel 13 by the liquid metal discharge nozzle 29.
taken back inside.

The heat exchanger 25 of this unit type purification bag W121 uses a helical coil type heat transfer tube and Shun-1.

The shell has a double structure consisting of an inner cylinder 26 and an outer shell cylinder 27, and a heat exchanger with a hollow central part is used. By using such a heat exchanger, the newly created space in the center can be used for routing the piping 5 and the piping 6 of the electromagnetic pump cooling system, or as a passage for the cable 8 and the like.

In this embodiment, an example is shown in which the electromagnetic flowmeter 2 is arranged in the cavity in the center of the heat exchanger, but in this embodiment, the electromagnetic pump installed in the upper and lower spaces of the heat exchanger 25 is It is also possible to arrange all or part of the heat exchanger 1 and the cold trap 4 in the central space of the heat exchanger 25.

When the purification equipment is placed in an environment with high temperatures and high radiation, in order to reduce heat loss and protect the equipment from heat and radiation, a heat insulating structure 23 and a radiation shield are installed as shown in Figure 1. Since structure 24 is also required, this also means that
Although this is a space constraint when designing a unit-type purification system, using a heat exchanger with a hollow center and a double shell structure as described above, the center cavity can be used for pipes, cables, etc. By using it not only as a passageway but also for arranging other equipment, it is possible to reduce not only the radial dimension of the purification device but also the longitudinal dimension, which can be expected to make the purification device more compact. .

Furthermore, by forming the heat exchanger with a double shell structure and narrowing the flow path of the shell-side fluid, the flow velocity of the shell-side fluid is increased, uneven flow is less likely to occur, and heat exchange performance is also improved.

Therefore, by using this double-shell heat exchanger in a unit-type purification device, it is possible to create a purification device that increases the purification capacity in the same space, or conversely, to make it more compact while maintaining the purification capacity. A purification device can be designed.

〔Effect of the invention〕

According to the present invention, it is possible to design a purification device that increases the purification capacity in the same space, or conversely, a liquid metal purification device that maintains the purification capacity and is made more compact, thereby making it possible to design a liquid metal purification device that increases the purification capacity in the same space. This has two major effects.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the structure of a primary coolant purification device for a tank-type fast breeder reactor, which is an embodiment of the liquid metal purification device of the present invention;
Figure 2 is a perspective view showing details of the structure of the heat exchanger in Figure 1;
FIG. 3 is an explanatory diagram of the reactor structure of a tank-type fast breeder reactor using the purification device of FIG. 1, and FIG. 4 is a system diagram of a conventional liquid metal purification system. Figure 5 is a diagram of the cold trap operating principle, Figure 6 is an explanatory diagram of a specific example of the liquid metal purification system shown in Figure 4, and Figure 7 is a case in which a unit type liquid metal purification device is placed in a tank type high speed KTL breeder reactor. FIG. 8 is a characteristic diagram showing the relationship between the large rotation plug diameter and the reactor vessel diameter when the unit type liquid metal deionization device is used in a tank type fast breeder reactor. DESCRIPTION OF SYMBOLS 1... Electromagnetic pump, 2... Current flow meter, 4... Cold trap, 5... Piping, 6... Electromagnetic pump cooling system, 7... Cold trap cooling system, 8... Various cables, 22... Container, 23... Heat insulation structure, 24
...radiation shielding structure, 25...heat exchanger, 26...
- (Heat exchanger) Shell inner cylinder, 27... (Heat exchanger) Shell outer cylinder, 28... Liquid metal suction nozzle, 29...
Liquid metal discharge nozzle.

Claims (1)

[Claims] 1. An electromagnetic pump for circulating liquid metal, an electromagnetic flowmeter for measuring the flow rate of the liquid metal, a heat exchanger for pre-cooling the liquid metal, and removing impurities in the liquid metal. The electromagnetic pump, the electromagnetic flowmeter, the heat exchanger, the cold trap, and the piping connecting these are housed in one container, and the heat exchanger is It has a double shell consisting of an inner cylinder and an outer cylinder, and is hollow in the center, and at least one component other than the heat exchanger, the piping, and the cable are arranged in the hollow center. A liquid metal purification device characterized by: 2. At least one component other than the heat exchanger,
The liquid metal purification device according to claim 1, which is an electromagnetic flowmeter.