JPS6279802A - Cold trap - Google Patents

Abstract

PURPOSE:To obtain the titled cold trap wherein impurities in a liq. to be purified are deposited and accumulated on the wall of a passage and the clogging of the passage is prevented by providing a partition plate in a cylindrical impurity deposition body to form the passage and passing the liq. to be purified through the passage. CONSTITUTION:The cold trap has the function to remove impurities in liq. sodium, the function to cool the liq. sodium by a gas, and the function to exchange heat in the liq. sodium. An impurity removing device 21 having such functions is formed by zigzag arranging plural approximately semicircular partition plates 31 in the flow direction of the liq. in the cylindrical impurity deposition body 29. The liq. sodium meanders due to the partition plate 31 from an inlet hole 33 to an outlet hole 35. Meanwhile, the impurities in the liq. sodium are deposited and accumulated on the passage wall and the liq. sodium is purified.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] This invention relates to a cold trap for a nuclear reactor that purifies a liquid metal by precipitating impurities therein, such as liquid sodium.

(Technical background of the invention and its problems) Generally, in fast breeder reactors that use liquid metal such as liquid sodium as a coolant, a cold trap is used to remove impurities from the liquid sodium.Conventional cold traps is connected to a part of the main stream of the liquid sodium circulation system, and is provided with an impurity removal device 1 as shown in FIG. 6 inside.

This impurity removal device 1 has an impurity removal cylinder 3 in which multiple layers of wire mesh as a filtration medium are installed horizontally along the flow of liquid sodium. The liquid sodium is filtered while passing through these multilayer wire meshes, and impurities in the liquid sodium, such as oxides such as N20, are precipitated and removed.

However, the multilayer wire mesh used as a filtration medium is easily clogged, and therefore the flow path in the impurity removal device 1 is r! Highly usable by IM. In particular, since the concentration of impurities in liquid sodium is highest before it flows into the impurity removal device 1, the inflow side wire mesh group 5 of the multilayer wire mesh deposits impurities in the winter and becomes clogged. tend to block the flow path. Therefore, the lifespan of the impurity removal device 1 is short,
Cold traps must be serviced frequently.

In particular, when many R impurities flow into the cold trap in a short period of time, such as during an accident or operational error, the R life of the impurity removal device 1 is significantly shortened, and the reliability of the cold trap is reduced. Become.

Therefore, conventionally, as shown in FIG.
It has been proposed to increase the wire mesh area of the inflow side wire mesh group 9 to reduce the tendency of clogging. However, if the diameter of the impurity removing device 7 is made large in this way, the space required for installing the cold trap increases, and there is a drawback that an increase in cost is unavoidable.

[Purpose of the invention]

This invention was made in consideration of the above facts, and an object of the present invention is to provide a cold trap that can prevent the flow path in the impurity removal device from clogging and extend the life of the impurity removal device. shall be.

[Essentials of invention]

In order to achieve the above object, the cold trap according to the present invention includes the above-mentioned cold trap which is attached to an impurity removal device and precipitates impurities in the liquid to be purified while the liquid to be purified passes through the impurity removal device. The impurity removal device is composed of an impurity precipitation cylinder and a partition plate disposed inside the impurity precipitation cylinder, which form a flow path, and in the process of the liquid to be purified passing through the flow path, the The structure is such that impurities in the liquid to be purified adhere to the walls of the flow path.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a longitudinal sectional view showing a first embodiment of the cold trap according to the present invention.

The cold trap 11 has an impurity removal function that removes impurities from a liquid metal such as liquid sodium, and a cold trap 11 that cools the liquid sodium with gas. It has a cooling function and a heat exchange function for exchanging heat between liquid sodium.

Among these, the impurity removal function is to transfer liquid sodium from the main stream of liquid sodium circulation to the inflow pipe 13 and the pre-cooled PiI cylinder 15.
The liquid sl-lium is introduced into a sealed tank via a connecting pipe 17, and after being purified by an impurity removal device 21 disposed in the sealed tank 19, it is passed from the upper plenum 23. It returns to the main flow of liquid sodium circulation via the delivery pipe 25.

Further, the delivery pipe 25 is disposed through the inside of the preliminary cooling cylinder 15. Therefore, the heat exchange ii in the cold trap 11 is performed between the high temperature liquid sodium flowing in the precooling cylinder 15 and the low humidity liquid sodium flowing in the delivery pipe 25 as purified liquid. This heat exchange cools the liquid sodium fed into the closed tank 19 before it is fed.

Further, the outer periphery of the sealed tank 19 is covered with a cooling cylinder 27,
N2 gas and air flow between the sealed tank 19 and the cooling cylinder 27. The liquid sodium in the closed tank 19 is cooled by this flowing N2 gas and air. This is the above-mentioned cooling function of the cold trap 11. This I
impurities in liquid sodium become supersaturated.

Impurity removal device 21 of such cold trap 11
is shown in Figure 1.

In this impurity removal device 21, a plurality of substantially semicircular partition plates 31 are attached within a cylindrical impurity precipitation cylinder 29. These partition plates 31 are arranged alternately in a grid pattern with respect to the flow direction of liquid sodium. Therefore, due to the inner wall of the impurity precipitation cylinder 29 and the condensate partition plate 31, the flow path 3 meandering from the inflow hole 33 to the outflow hole 35.
7 is formed. Therefore, while the liquid sodium flows through the flow path 37, impurities in the liquid sodium adhere to and accumulate on the flow path wall, that is, the inner wall of the impurity precipitation cylinder 29 and the partition plate 31. The liquid sodium is purified by this adhesion and deposition, and flows out from the outflow hole 35 into the upper blemish 23.

According to this embodiment, the flow path area of the flow path 37 can be increased, and even if impurities are deposited on the inner wall of the flow path 37, the flow path 37 can be prevented from being blocked. In particular, liquid sodium has a high impurity concentration in the flow path 37 near the inflow hole 33, so if the flow path area near the inflow hole 33 is made large and the flow path area is gradually decreased along the flow, it is possible to
It is possible to more reliably prevent flow path blockage in the flow path 37 near No. 3. Also, in this way, the inflow hole 3
By configuring the flow path area around 3 to be large, flow path blockage can be similarly avoided even in the event of an accident where a large amount of liquid sodium flows into the cold trap 11 in a short period of time. In this way, since clogging of rJ1 in the flow path 37 can be prevented, the life of the impurity removal device 21 can be extended, the frequency of maintenance and inspection can be reduced, and the reliability of the cold trap can be improved. can.

Furthermore, in this embodiment, if it is desired to lengthen the flow path 37, there is a large degree of freedom in setting the equal flow path 37 by increasing the number of partition plates 31, so the outer diameter dimension of the impurity precipitation cylinder 29 is also restricted. can be set relatively small. As a result, the installation space for the cold trap 11 can be reduced. Generally, the temperature inside the impurity precipitation cylinder 29 needs to be maintained constant, so even when a heat-insulating structure is provided on the outer periphery of the impurity precipitation cylinder 29, the outer diameter of the impurity precipitation cylinder 29 must be made smaller accordingly. If designed, the installation space of the cold trap 11 will not be increased.

Further, in the above embodiment, since the impurities are precipitated over almost the entire channel wall composed of the impurity precipitation cylinder 29 and the partition plate 31, there is no bias in the precipitated region. Therefore, the impurity trapping capacity per unit area of the inner wall of the impurity precipitation cylinder 29 and the partition plate 31, which contribute to the precipitation of impurities, increases.
Impurity removal efficiency can be improved.

In addition, there is no need to install multiple layers of wire mesh inside the impurity removal cylinder 3 (Fig. 6) as in the past, and only several partition plates 31 are required, reducing the need to open the mold of the impurity removal device 21. can do. At the same time, costs can be reduced.

3 to 5 show impurity precipitation devices in second, third, and fourth embodiments of the cold trap, respectively. In these figures, the same reference numerals as 711 in the first embodiment are given the same reference numerals, and the explanation thereof will be omitted.

In the impurity precipitation device 41 shown in FIG. 3, the partition plate 43 disposed within the impurity precipitation cylinder 29 is rectangular and is arranged substantially parallel to the flow direction of liquid sodium. Therefore, the flow path in the impurity removal device 41 is connected to these partition plates 4.
3, a plurality of channels 45 parallel to the flow of liquid sodium
It is branched into.

Therefore, the liquid sodium flowing through the channel 45 can flow without stagnation, and impurities are uniformly attached to the entire partition plate 43. Furthermore, since a plurality of channels 45 are provided,
Even if the flow path - is blocked due to clogging, the flow is ensured by the other flow paths, and the impurity removal device 41 will not be blocked.

The impurity removal device 51 shown in FIG. 4 is constructed by twisting a partition plate 53 disposed inside the impurity precipitation cylinder 29 by half a turn with respect to the flow direction of liquid sodium. Therefore, as the liquid sodium flows along this twisted flow path 55, centrifugal force acts on the impurities in the liquid sodium. As a result, the number of impurities moving in the direction of the impurity precipitation cylinder 29 increases, and the impurities adhere to and deposit on the impurity precipitation cylinder 29! lff1 increases.

The impurity removal device 61 shown in FIG. 5 has a partition plate 63 installed inside the impurity precipitation cylinder 29 similarly to the partition plate 31 shown in FIG. Ru. Therefore, in the initial stage of impurity removal, liquid sodium passes through the partition plate 63 as shown by arrow A and flows inside the impurity precipitation cylinder 29 along its axial direction. While passing through the partition plate 63, the liquid sodium is filtered and impurities are deposited on the partition plate 63. Eventually, the amount of impurities deposited on the partition plate 63 increases and this partition plate 63 becomes clogged, and the liquid sodium flows in a meandering manner within the impurity precipitation cylinder 29 as shown by arrow B, as in the second embodiment. . During this time, impurities in the liquid Natrium Cum adhere to and accumulate on the partition plate 63 and the inner wall of the impurity precipitation cylinder 29. In the impurity removal apparatus of this fourth embodiment, the impurity removal process is carried out in two stages (
The initial stage is filtration (later, adhesion/deposition), and since many W impurities are captured by filtration in the initial stage, the capture efficiency of the impurity removal device 61 can be greatly improved.

The cold trap impurity removal devices 41, 51, and 61 in each of these embodiments can also provide the same effects as the impurity removal device 21 of the first embodiment, in addition to the above-mentioned effects.

[Effects of the Invention] As described above, according to the cold 1 wrap according to the present invention, the impurity removal device is composed of an impurity precipitation cylinder and a partition plate disposed inside the impurity precipitation cylinder, and The impurities in the liquid to be treated adhere to and accumulate on the walls of the flow path as the liquid to be treated passes through the flow path, so the flow path area of the impurity removal device has been As a result, opening of the flow path of the impurity removal device due to clogging is prevented, and the life of the impurity removal device can be extended.

[Brief explanation of drawings]

FIG. 1 shows an impurity removal device applied to a first embodiment of a cold trap according to the present invention. i cross section, 2nd
The figure is a vertical cross-sectional view showing a cold trap to which the impurity removal device of FIG. 1 is applied, and FIGS. FIGS. 6 and 7 are longitudinal sectional views showing an impurity removal device applied to a conventional cold trap, respectively. 11...Cold trap, 21.41.51゜61
... Impurity removal device, 29 ... Impurity precipitation cylinder, 3
1.43,53.63...Partition plate, 37,45°55
...Flow path. Representative Patent Attorneys Nori Chika Ken Yudo Mitsumata Hiroshi Bunge 3 Figures 4 Omura L 5 Figures L 6 Figures

Claims (1)

[Claims] 1. A cold trap that includes an impurity removal device and precipitates impurities in the liquid to be purified while the liquid to be purified passes through the impurity removal device, wherein the impurity removal device precipitates impurities. It is composed of a cylindrical body and a partition plate disposed inside the impurity precipitation cylinder, and these form a flow path, and in the process of the liquid to be purified passing through the flow path, impurities in the liquid to be purified are removed. A cold trap characterized in that it is configured to be able to adhere to and deposit on the channel wall. 2. The cold trap according to claim 1, wherein the partition plate is disposed in the impurity precipitation cylinder at an angle with respect to the flow direction of the liquid to be purified. 3. The cold trap according to claim 1, wherein the partition plate is arranged approximately parallel to the flow direction of the liquid to be purified within the impurity precipitation cylinder. 4. The cold trap according to claim 1, wherein the partition plate is twisted with respect to the flow direction of the liquid to be purified within the impurity precipitation cylinder. 5. The partition plate is composed of a filtration medium, and this filtration medium forms a new flow path in the process of filtering the liquid to be purified, and while the liquid to be purified flows through this new flow path, the impurity precipitation cylinder The cold trap according to claim 1, wherein the cold trap is configured such that impurities in the liquid to be purified can adhere to and be buried in the partition plate.