JPS61185303A - Cold trap - Google Patents

Abstract

PURPOSE:To simplify a structure and to attain reduction of labor by dispensing with driving force, by cooling a liquid by flowing the same in the heat pipe immersed in a liquid to be purified. CONSTITUTION:The upper end part of a heat pipe 46 is protruded to the outside of a storage tank 52 and cooled by a cooling fan 54 to generate the movement of heat in the heat pipe 46 and the part immersed in a liquid of said heat pipe 46 is cooled to also cool the liquid or impurity collecting material 48 around the heat pipe 46. The liquid in a cylindrical heat insulating frame body 44 is cooled and flowed down through the impurity collecting material 48. This liquid is further cooled by the heat pipe 46 to precipitate impurities and the purified liquid is flowed out from a lower opening part 42.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an apparatus for removing impurities from a liquid to be purified, and more particularly to a submerged cold trap using a heat pipe as a cooling means. It is something.

Although the present invention is not particularly limited, it is a particularly effective apparatus for purifying liquid sodium used as a coolant in fast breeder reactors and the like.

[Prior art] One of the devices for purifying liquids is a cold trap.
Widely used to purify liquid sodium, etc. (as is well known), cold traps take advantage of the fact that the solubility of impurities in liquids decreases at low temperatures, and keep the temperature of the liquid to be purified below the saturation temperature of the impurities. This is a device that precipitates and removes impurities.

An example of a conventional cold trap used for purifying liquid sodium is shown in FIG. This cold trap has a double structure of an inner cylinder 10 and an outer cylinder 12.
The inside of the tube becomes a flow path for liquid sodium, and the space between the inner cylinder 10 and the outer cylinder 12 becomes a flow path for cooling gas. An economizer 14 is provided above the inner cylinder 10, and an economizer 14 is provided below it.
L-ram flow path guide plates 16 are installed in multiple stages, and an impurity trapping material 18 made of stainless steel wire mesh or the like is placed between them.
The structure is filled with

The cooling gas enters from the gas inlet 20 at the lower end of the outer cylinder, cools the inside of the inner cylinder 10 by passing between the cooling fins 22, and exits from the gas outlet 24 at the upper end of the outer cylinder.

The sodium to be purified enters from the sodium inlet 26 at the upper end of the inner cylinder, is cooled by heat exchange in the economizer 14, and is further cooled by cooling gas as it flows through the impurity trapping material 18 along the flow path regulated by the guide plate 16. do. After the liquid sodium reaches its lowest temperature at the lower end of the inner cylinder 10, it rises through the central pipe 28. During that time, heat exchange takes place, so the temperature gradually rises, and it passes through the spiral tube of the economizer 14, is further heated, and returns to the sodium loop side from the sodium outlet 30.

In the same figure, the reference numeral 32 is a thermocouple for measuring the temperature of the thorium at the lower end of the inner cylinder, the reference numeral 34 is a drain line,
Reference numeral 36 indicates a heat insulating material.

[Problems to be Solved by the Invention] As described above, conventional cold traps have the disadvantages that they have a very complicated structure, are difficult to miniaturize, and are difficult to manufacture, and it is difficult to control the temperature of each part to a predetermined value. be. Although not shown in Figure 4, a driving force such as an electromagnetic pump is required to flow liquid sodium into the cold trap, and instrumentation such as an electromagnetic flowmeter is installed to control the flow rate. Moreover, it also requires the installation of equipment such as a large cooling blower and a heating device for temperature control, which has the disadvantage of being extremely expensive.

Furthermore, because conventional cold traps are built directly into the sodium loop, they cannot be easily installed and removed, and it is also difficult to remove impurities captured during operation from the loop. If the precipitation of impurities progresses and the capture material becomes clogged and operation becomes impossible, the cold trap must be heated to re-dissolve the impurities in the sodium before being discharged into the storage tank.
The problem is that it takes a long time to regenerate the cold trap, and a large amount of sodium is discharged along with impurities.

The purpose of the present invention is to solve the above-mentioned drawbacks of the conventional technology, to have an extremely simple structure, suitable for miniaturization, to reduce manufacturing costs, and to be able to be applied to any place where the liquid to be purified is present. The object of the present invention is to provide a cold trap with a new structure that can be easily installed and removed, and in particular does not require forced circulation of liquid using an electromagnetic pump or the like.

[Means for Solving the Problems] The present invention, which can achieve the above objects, is a device in which a heat pipe is applied to cool a liquid that is necessary to have a function as a cold trap. ,
As shown in FIG. 1, there is a cylindrical heat insulating frame 44 having openings 40, 42 at least at the upper and lower sides, a heat pipe 46 inserted into the frame 44, and a heat pipe 46 inserted into the frame 44. 46 and an impurity trapping material 48 filled between the frame body 44 and the frame body 44.

The frame body 44 is immersed in the liquid such that its opening 40.42 is located below the liquid level 50 of the liquid to be purified, and the heat pipe 46 has its upper end below the liquid level 50.
It has a configuration in which it is provided so as to protrude upwards and is cooled. For example, a structure is adopted in which the heat pipe 46 is attached to the upper wall surface of the storage tank 52 for the liquid to be purified, and its lower half is immersed in the liquid.

In order to increase the cooling efficiency of the heat pipe 46, it is desirable to attach cooling fins 52 to the upper end thereof. When the liquid to be purified is liquid sodium, the impurity trapping material 4
As the material 8, a stainless steel mesh or wire-like material is used.

The cylindrical frame 44 functions to partition the inside and outside of the liquid and maintain a temperature difference, and therefore, a material or structure with good heat insulation properties is used.

[Function] The upper end of the heat pipe 46 protrudes to the outside of the storage tank 52, and by natural cooling or forced cooling with the cooling fins 54, heat transfer occurs within the heat pipe 46, and the heat pipe 46 is immersed in the liquid. part is cooled and the heat pipe 4
The liquid and impurity trapping material 48 surrounding the filter 6 are also cooled. Therefore, as shown in FIG. 2, the temperature distribution of the liquid at a certain level in the storage tank is such that the temperature decreases near the heat pipe 46, increases as it moves away from the heat pipe 46, and eventually reaches a constant value.

Therefore, the liquid inside the cylindrical heat insulating frame 44 is cooled, its volume decreases, and its specific gravity increases, so the impurity trapping material 48
flows down through the In this manner, heat is further removed from the flowing liquid by the heat pipe 46, so that the temperature becomes low, and when the temperature falls below the saturation temperature of the impurities contained therein, the impurities are precipitated on the trapping material 48. The purified liquid with a small amount of impurities then flows out from the lower opening 42 as shown by arrow a.

In this way, the liquid inside the cylindrical heat insulating frame 44 is cooled and flows downward, and the volume of the liquid in that part becomes smaller, so a difference in liquid level tends to occur between the inside and outside of the frame 44. , the surrounding liquid flows in from the upper opening 40 of the frame 44 as indicated by the arrow. In this way, simply by cooling the upper end of the heat pipe 46, convection is caused in the liquid to flow down inside the frame, and purification is performed.

[Example] The present invention will be explained in more detail below.

FIG. 3 is an explanatory diagram showing an example of a storage tank incorporating a cold trap according to the present invention.

Since the basic structure of the cold trap is almost the same as that shown in FIG. 1, corresponding members are given the same reference numerals for ease of understanding.

In the cold trap, a flange 56 attached to the lower side of the cooling fins 54 connects to the sodium storage tank 5.
It is placed and suspended on a flange 58 formed on the upper surface of 2. Here, the storage tank 52 is connected to the sodium loop etc. by a piping 60, and the piping 60 can be used to drain sodium from the sodium loop and return sodium to the sodium loop. The state shown in the figure is a state in which the sodium flowing in the sodium test loop is drained into the sodium storage tank 52 upon completion of the test. A heater 62 for heating the sodium is attached to the wall of the storage tank 52, and the storage tank 52 and the heater 62 are covered with a heat insulating material 64.

Now, as mentioned above, the cold trap includes the cylindrical insulating frame 44, the heat pipe 46 inserted into the inside thereof,
An impurity trapping material 48 is provided between the heat pipe 46 and the frame 44.

The cylindrical heat-insulating frame 44 is made of a structural material such as stainless steel, and the portion immersed in liquid sodium has a heat-insulating function. For example, as shown in an enlarged view in FIG.
It is possible to adopt a heat insulating structure sandwiched with etc.

Such a cylindrical heat insulating frame 44 has an upper opening 40.
, a lower opening 42 , and a plurality of liquid flow ports 66 provided in the middle part, and the upper end is connected to a mounting flange 56 . A large number of sodium flow guide plates 68 are alternately provided horizontally between the heat pipe 46 and the frame 44 surrounding it. This sodium flow guide plate 68 functions to regulate and lengthen the flow path of the liquid sodium flowing down from above, and also to hold the impurity capture material 48 filled inside. As the impurity trapping material 48, for example, a stainless steel net or wire-like material is used. A cooling fin 54 is attached to the upper end of the heat pipe 46 . Therefore, this cold trap has its flange portion 56 connected to the storage tank 5.
By separating it from the flange section 58 on the second side, it is possible to easily pull it out as a whole.

Next, the operation of this device will be explained. Cooling fin 54
By forcibly cooling the portion, heat transfer from the sodium occurs through the heat pipe 46, and the sodium temperature inside the frame 44 becomes lower than the sodium temperature outside the frame. The cooled sodium in the frame 44 becomes heavier in specific gravity and gradually moves downward, while at the same time passing through the upper opening 40 of the frame 44 (as indicated by the arrow) or forming around the surrounding high temperature sodium. The liquid flows through the liquid flow port 66 (indicated by arrow C). When the sodium flowing down inside the frame body 44 is cooled to below the saturation temperature of the impurities contained therein, an amount of impurities corresponding to the difference in solubility adheres to the impurity trapping material 48, the flow guide plate 68, etc. Captured. The purified sodium flows out through the lower opening 42. Since the temperature of the sodium in the storage tank 52 is controlled to several hundred degrees by the heater 62, the low temperature sodium flowing out from the lower end of the cold trap is given heat by the high temperature sodium in the storage tank 52, so its specific gravity becomes lighter. The volume also expands and gradually rises inside the tank as shown by arrow d.

In this way, by only cooling the upper end of the butt pipe 46, the sodium in the storage tank 52 is removed from the upper opening 4.
A natural circulation occurs in a loop in which the liquid enters the frame 44 from 0, cools and flows from above to below, flows out from the lower opening 42, and rises in the tank. Since impurities are precipitated in the trapping material 48 by cooling, the impurities in the sodium can be removed by maintaining such a flow for a long time.

From the point of view of operation as a cold trap, frame 4
It is desirable that the openings formed in 4 be provided only in the upper and lower parts. This is because the temperature of the sodium flowing in from the intermediate flow port is higher than that of the sodium flowing down from above within the frame, so there is a risk that the cooling effect of the heat pipe 46 will be reduced. However, in cases where the liquid level fluctuates greatly within the storage tank, it is more effective to form a plurality of flow ports on the side of the frame as in this embodiment. In other words, even if the liquid level drops from the liquid level shown as L1 in the same figure to the liquid level shown as L2, since several communication holes are formed in the middle part of the frame 44, they will not open when the liquid level is below L2. This is because sodium can flow in through the flow openings, creating a cold trap effect.

Of course, even if the cold trap has openings only at the top and bottom, the entire cold trap may be moved up and down according to fluctuations in the liquid level so that the upper opening is located below the liquid level. In the case of this example, there is an advantage that the handling is simplified as no adjustment is necessary.

[Effects of the Invention] As described above, the present invention uses a cold trap as a cooling means and is immersed in the liquid to be purified, so the structure is extremely simple and the design is easy and easy to manufacture. Costs can be significantly reduced. In addition, it can be installed anywhere where liquid exists, and even if the impurity capture material becomes clogged, it can be easily taken out and disposed of, making it extremely easy to handle. Since no driving force is required to circulate the liquid, it has excellent effects such as labor saving.

Furthermore, when the cold trap according to the present invention is used in, for example, an experimental facility that uses liquid sodium, by inserting the cold trap into a storage tank when no tests are being conducted, sodium is naturally circulated over a long period of time and impurities are captured. This has the advantage that purified sodium can be introduced into the sodium testing loop when necessary, and sodium testing equipment can be used effectively.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing a schematic configuration of a cold trap according to the present invention, Fig. 2 is an explanatory diagram showing the temperature distribution of the surrounding liquid when a heat pipe is used, and Fig. 3 is an explanatory diagram showing an embodiment of the present invention. The explanatory diagram, FIG. 4, is an explanatory diagram of the prior art. 40... Upper opening, 42... Lower opening, 44
・Insulating frame body, 46・Heat pipe, 48・Impurity trapping material, 50・Liquid level, 52・Storage tank, 54・
Cooling fins. Patent applicant: Power Reactor and Nuclear Fuel Development Corporation Representative Shigeru Hitoshi Estimate Figure 1 Figure 2 Distance from heat pipe Figure 3 Figure 4

Claims (1)

[Scope of Claims] 1. A cylindrical insulating frame having openings at the upper and lower sides and immersed in the liquid to be purified, and the frame having an upper end protruding above the liquid level. A cold trap comprising: a heat pipe inserted into the cold trap; and an impurity trapping material filled between the heat pipe and the frame. 2. The cold trap according to claim 1, wherein the heat pipe has a cooling fin at its upper end. 3. A patent in which a large number of liquid flow guide plates are provided between a heat pipe and a frame surrounding it to regulate the flow path of liquid flowing down, and an impurity trapping material is filled between the liquid flow guide plates. A cold trap according to claim 1. 4. The cold trap according to claim 1, wherein the cylindrical heat insulating frame has a structure in which a plurality of liquid flow ports are opened in the middle part of the wall surface.