JPS5814861B2 - Cold trap device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a diffusion-type cold trap particularly suitable for purifying liquid metal with high impurity concentration, and combines the diffusion-type cold trap with a conventional packed bed type cold trap,
The present invention relates to a cold trap device capable of refining a liquid metal with a high impurity concentration to one with an extremely low impurity concentration.

As is well known, liquid metal, particularly liquid sodium, is widely used as a coolant in nuclear reactors, and cold traps play a very important role in controlling the purity of the liquid metal.

However, to conclude, the current situation is that a cold trap that can operate stably over a long period of time has not yet been developed.

In particular, in the secondary cooling system of a fast breeder reactor power plant, ferrite steel is used in the steam generator system, which generates impurities that are difficult to dissolve and have a high plugging temperature, and the steam generator is susceptible to water leaks. If a water leak occurs, there is a risk that a large amount of impurities will be generated.

These impurities must be kept as low as possible to avoid corrosion and pipe blockage problems.

An example of a cold trap 1 according to the prior art, as shown in FIG. 1, is one in which an economizer 2 having a double pipe structure and a mesh part 3 for trapping impurities are separated.

However, during operation of the cold trap having such a structure, a flow passage clogging phenomenon often occurred in the economizer section 2.

The reason for this is that, as shown in the plugging measurement example shown in Figure 2, impurities with different saturation temperatures are mixed in sodium and lium. This was because impurities at the first break point a precipitated near the economizer 2 when the trap was operated.

Moreover, as is clear from FIG. 2, the substance corresponding to the first break point a usually has the property that once a clogging phenomenon occurs, it will not dissolve unless the degree of superheating ΔT1 is increased considerably.

This degree of superheating ΔT1 may reach 200 to 300° C. or more, and in the case of such poorly soluble substances, it is often fatal and almost no recovery of the flow rate can be expected.

To improve this point, there is a cold trap having a structure in which an economizer part and a mesh part are housed in an integrated container.

However, whether it is a separate type like the former or an integrated type like the latter, the liquid metal is purified in a cooled mesh section regardless of the impurity concentration in the liquid metal.

Therefore, even if there are no problems when purifying liquid metal with a low impurity concentration, if the impurity concentration increases significantly for some reason, such as in the case of a water leak accident, the Since there is a risk of clogging at the operating temperature, the operating temperature must be increased.

However, in this case, the impurities in the cold trap are expelled and diffused, which may cause local internal blockage.

Therefore, with such a conventional cold trap, it is difficult to remove impurities ranging from low concentration to high concentration.

The purpose of the present invention is to solve such problems,
It is suitable for purifying liquid metals where multiple plugging phenomenon occurs, and can efficiently purify liquid metals with high impurity concentration to medium or low concentrations without the risk of flow path blockage. The object of the present invention is to provide a diffusion-type cold trap for high impurity concentrations that can remove a large amount of impurities even in the event of a leakage accident, is easy to dismantle, and can be easily regenerated by simply replacing some parts. The object of the present invention is to provide a cold trap device which combines such a diffusion type cold trap and a packed bed type cold trap and is capable of removing impurities ranging from high concentration to low concentration.

Hereinafter, the present invention will be explained in detail based on the drawings.

FIG. 3 is an explanatory diagram of an embodiment of the diffusion type cold trap for high impurity concentration according to the present invention, and FIG. 4 shows the container structure thereof.

The container 11 has a vertical cylindrical shape, has a protrusion 12 that largely projects upward at the center of the bottom, and the inner surface of the container is lined with a mesh 13.

This mesh 13 is a base material layer for precipitation of impurities in the fluid.

The upper lid 14 is attached to the upper end of the container 11 by an O-ring 15 and a lip seal weld 16, so that the interior of the container 11 can be kept airtight.

Most of the members to be inserted into the container 11 are its lid 14.
The container and lid are configured in a so-called cartridge type so that all the insertion members can be removed by removing the lid 14.

That is, a cylindrical heat shield 17 is vertically provided on the lower surface of the lid 14 .

The heat shield 17 is located within the container 11 so as to just surround the protrusion 12 .

Further, an inflow pipe 18 is attached to the lid 14 so as to open toward the internal space surrounded by the heat shield 17, and an outflow pipe 19 is connected to the lid 14 so as to communicate with the space between the heat shield 17 and the outer wall of the container. is installed.

That is, the cylindrical heat shield 17 functions to separate and shield the downward flow of liquid metal from the inflow pipe 18 and the upward flow to the outflow pipe 19.

Further, a spiral economizer tube 20 is disposed between the heat shield 17 and the protrusion 12, and both the inlet side 21 and the outlet side 22 of the economizer tube 20 are fixed to the lid 14.

If a cooled fluid is not available, a heat pipe or a blower duct may be inserted inside the protrusion 12 for cooling.

However, since it is usually used in combination with a conventional cold trap and is operated at a higher temperature than that, the liquid metal flowing out from the conventional cold trap is passed through the economizer tube 20 and heated. It is economically preferable to perform the exchange.

A drain pipe 23 is provided at the bottom of the container 11.

The cold 1 wrap configured in this manner operates as follows.

The high-temperature, high-concentration liquid metal flowing from the inflow pipe 18 exchanges heat with the low-temperature fluid flowing through the economizer pipe 20, flows down outside the economizer pipe 20, and reaches the bottom of the container 11.

The impurities precipitated during this time adhere to the mesh 13, which is the crystal nucleus, while crystallizing and are removed. It rises between the heat shield 17 and the container wall and flows out from the outflow pipe 19 while becoming relatively pure.

Once the container 11 is full of impurities, the liquid metal in the container 11 can be drained from the drain pipe 23.

FIG. 5 is an explanatory diagram of an embodiment of the cold trap device according to the present invention, in which a packed bed type cold trap for low impurity concentration and a diffusion type cold trap for high impurity concentration are interconnected. It is a device.

The diffusion type cold trap 10 for high impurity concentration is the same as that shown in FIG. 3, so its detailed description will be omitted.

However, the duct 2 equipped with the blower 24 inside the protrusion 12
5 has been inserted.

In the packed bed type cold trap 30 for low impurity concentration, a center pipe 32 is inserted into the center of a container 31, and a packed layer 33 of a porous base material such as wire or mesh for precipitating impurities in the fluid is arranged around the center pipe 32. has been done.

A fluid inlet pipe 34 is attached to the upper part of the container 31, and a fluid outlet pipe 35 is attached to the upper end of the center pipe 32, that is, a portion protruding from the container 31.

A blower 36 is installed below the container 31 to cool the entire cold trap 30, and a heat sink 37 is installed on the outer wall of the container 31 to heat the entire cold trap 30. It has become.

Now, the mutual communication between the diffusion type cold trap 10 and the packed bed type cold trap 30 is as follows.

The outflow pipe 19 is connected to an electromagnetic pump 41 and a first on-off valve 42
A first on-off valve 43 is connected to the fluid introduction pipe 34 via a first on-off valve 43 , and a second on-off valve 44 is connected to the upstream side of the first on-off valve 42 .
It is connected to the outlet side 22 of the economizer tube 20 by a first bypass tube 45 with a first bypass tube 45 provided with a first bypass tube 45 having a first bypass tube 45 with a first bypass tube 45 having a first bypass tube 45 having a first bypass tube 45 with a first bypass tube 45 having a first bypass tube 45 having a first bypass tube 45 with a first bypass tube 45 having a first bypass tube 45 connected to the outlet side 22 of the economizer tube 20 so as to be able to exit the loop.

The fluid outlet pipe 35 is connected to an electromagnetic flowmeter 46 and a third on-off valve 4.
The economizer tube 2 is connected to the economizer tube 2 by a second connecting tube 48 having 7
0, and the upstream side of the third on-off valve 47 is a second bypass pipe 50 equipped with a fourth on-off valve 49.
and is connected to the inflow pipe 18.

Next, the operation of this cold trap device will be explained.

In the case of a normal liquid metal with a low impurity concentration, the operation of the blower 24 of the diffusion type cold trap 10 is stopped, the blower 36 of the packed bed type cold trap 30 is operated, and the packed bed type cold trap 30 is kept at a predetermined operating temperature. Cool to

In addition, the first on-off valve 42 is opened, the second on-off valve 44 is closed,
The third on-off valve 47 is opened, the fourth on-off valve 49 is closed, and the electromagnetic pump 41 is operated.

The high temperature liquid metal containing impurities flows into the diffusion type cold trap 10 from the inlet pipe 18 and descends while exchanging heat with the cooled low temperature liquid metal passing through the economizer tube 20.

Precipitates at high temperatures adhere to the mesh 13 and are removed, rising between the heat shield 17 and the vertical container 11.

A first connecting pipe 43 that is pumped up from the outflow pipe 19 by the operation of the electromagnetic pump 41 and has a first on-off valve 42
The fluid enters the packed bed type cold trap 30 from the fluid introduction pipe 34 through the fluid introduction pipe 34 .

The liquid metal that has flowed into the cold trap 30 is cooled by the operation of the blower 36, passes through a filling layer 33 made of mesh or wire, impurities adhere to the filling layer 33, are removed, and the purified liquid metal is Center pipe 32
from the fluid introduction pipe 35 to the second connecting pipe 4.
8, the flow rate is measured by an electromagnetic flowmeter 46, flows through the economizer tube 20 through the third on-off valve 47, is heated by exchanging heat with the surrounding high-temperature liquid metal, and returns to the loop system.

In this circulation system, the diffusion type cold trap 10 only has to absorb heat; the cold trap 10 attaches and removes precipitates at high temperatures, and the packed bed type cold trap 30 removes precipitates at low temperatures. This removes the adhesion and purifies the liquid metal.

If there is a large amount of impurities in the steam generator, such as in the event of a water leak accident, and there is a risk that the packed bed type cold trap 30 will be clogged, the first opening/closing Only the diffusion type cold trap 10 is operated with the valve 42 closed, the second on-off valve 44 opened, and the fourth on-off valve 49 closed.

That is, the liquid metal pumped up by the electromagnetic pump 41 is returned to the loop system through the first bypass pipe 45.

At this time, if necessary, the blower 24 is operated to keep the temperature at an appropriate level, and impurities are attached to the mesh 13 and removed.

After continuing this operation for a while to purify the product to an appropriate concentration, the product is passed through the packed bed type cold trap 30 in a normal operating manner.

Moreover, when the packed bed type cold trap 30 becomes a little clogged, the cold trap 30 can be regenerated as follows.

The first on-off valve 42 is opened, the second on-off valve 44 is closed, the third on-off valve 47 is closed, the fourth on-off valve 49 is opened, and the heater 3
7 to heat the packed bed cold trap 30.

When the liquid metal is sodium, the temperature is increased to about 500°C or higher.

Impurities adhering to the mesh etc. are dissolved, and the liquid metal containing the impurities is caused to flow into the container 11 outside the economizer tube through the second bypass pipe 50.

At this time, a blower 24 is installed in the bottom protrusion 12 of the vertical container 11.
Cooling gas is introduced through the duct 25 for cooling.

Then, impurities transported from the packed bed type cold trap 30 are diffused and adhered to the lining mesh of the protrusion 12.

That is, the packed bed type cold trap 30 is set to a high temperature, the diffusion type cold trap 10 is set to a low temperature, and the electromagnetic pump 41 is set to a high temperature.
The liquid metal is circulated and impurities in the system are captured in the mesh portion 13 in the process.

In this way, the packed bed cold trap 30 can be regenerated.

Once the regeneration is complete, normal operation can be resumed using the method described above.

Furthermore, when the vertical container 11 is full of impurities,
After the liquid metal in the container 11 is discharged through the drain pipe 23, the lip seal welded portion 16 is cut and replaced with a new vertical container.

Old vertical containers can be reused by cleaning them.

Since the present invention is a cold trap device configured as described above, the diffusion type cold trap is particularly suitable for removing precipitates on the high temperature side of liquid metal where multiple plugging phenomenon occurs, and is suitable for removing liquid metal with high impurity concentration. efficiently and in large quantities,
In addition, it can be purified to medium or low concentrations without the risk of flow path blockages, and even in the unlikely event of a water leak from a steam generator, a large amount of impurities can be removed, and disassembly is easy. It has the remarkable effect of being easily reproducible by simply replacing parts, and the system that combines a diffusion type cold trap and a packed bed type cold trap can remove impurities from high to low concentrations. Even if the packed bed type cold trap becomes clogged, it can be easily regenerated.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of an example of a conventional cold trap, Figure 2
The figure is a diagram showing the relationship between the flow rate and temperature of sodium in which the multiple plugging phenomenon occurs, FIG. 3 is an explanatory diagram of an embodiment of the diffusion type cold trap according to the present invention, and FIG. FIG. 5 is an explanatory view of the mold container portion, and is an explanatory view of an embodiment of the cold trap device according to the present invention. 10... Diffusion type cold trap for high impurity concentration, 11... Vertical container, 12... Protrusion, 13... Lining mesh, 14... ...
・Lid body, 17... Heat shield, 18...
Inflow pipe, 19...Outflow pipe, 20...
・Economizer tube, 24...Blower, 30...
...Packed bed type cold trap for low impurity concentration, 3
1... Container, 33... Filled bed, 34...
...Fluid inlet pipe, 35...Fluid outlet pipe,
43...First connecting pipe, 48...Second
connecting pipe.

Claims (1)

[Scope of Claims] 1. A nearly cylindrical vertical container with a lid lined with a base material layer for precipitating impurities in a fluid; a cylindrical heat shield, a cooling unit inserted into an internal space surrounded by the heat shield, an inflow pipe attached to the lid so as to open toward the internal space, and a vertical container wall. and an outflow pipe attached to the lid so as to communicate with the space between the heat shield and the heat shield,
The fluid flowing in through the inflow pipe is cooled in the cooling section,
A diffusion-type cold trap device for high impurity concentrations that removes impurities by adhering them to the base material layer. 2. The vertical container has a shape in which the center of the bottom protrudes inward, and a heat pipe or a blower duct is inserted into the protrusion to form a cooling section. Apparatus described in section. 3. The device according to claim 1, wherein the cooling section is an economizer tube through which the cooled fluid flows and exchanges heat. 4 The vertical container has a shape in which the center of the bottom protrudes inward of the container, a heat pipe or a blower duct is inserted into the protrusion, and an economizer pipe through which the cooled fluid flows near the outer periphery of the protrusion. 2. The device according to claim 1, further comprising: a cooling section formed by a cooling section. 5 A cold trap device in which a packed bed type Coalt River Wrap for low impurity concentrations and a diffusion type cold trap for high impurity concentrations are interconnected, and the cold trap for low impurity concentrations traps impurities in the fluid inside the container. A cold trap for high impurity concentration has a packed layer of a porous base material for precipitation, and a fluid inlet pipe and a fluid outlet pipe are attached to the container. A substantially cylindrical vertical container with a lid lined with a lid, a cylindrical heat shield located inside the vertical container and having an upper end attached to the lower surface of the lid, and an interior surrounded by the heat shield. An economizer pipe inserted into the space, an inflow pipe attached to the lid so as to open toward the internal space, and an inflow pipe attached to the lid so as to communicate with the space between the vertical container wall and the heat shield. The outflow pipe and the fluid introduction pipe are connected by a first connecting pipe, and the fluid outlet pipe and the inflow side of the economizer pipe are connected by a second connecting pipe. Trap device. 6 A cold trap device in which a packed bed type cold trap for low impurity concentration and a diffusion type cold trap for high impurity concentration are interconnected, and the cold trap for low impurity concentration is used for precipitating impurities in the fluid inside the container. A cold trap for high impurity concentration is lined with a base material layer for precipitation of impurities in the fluid. a nearly cylindrical vertical container with a lid, a cylindrical heat shield located inside the vertical container and whose upper end is attached to the lower surface of the lid, and an internal space surrounded by the heat shield. The inserted economizer pipe, the inflow pipe attached to the lid so as to open toward the internal space, and the outflow pipe attached to the lid so as to communicate with the space between the vertical container wall and the heat shield. The outflow pipe and the fluid introduction pipe are connected by a first connecting pipe, the fluid outlet pipe and the inflow side of the economizer pipe are connected by a second connecting pipe, and the outflow pipe is connected to the fluid inlet pipe by a second connecting pipe. The first connecting pipe that connects the piping and the fluid introduction pipe is provided with a first on-off valve, and the upstream side of the first on-off valve and the outflow side of the economizer pipe are provided with a second on-off valve. Connected by 1 bypass pipe,
A third on-off valve is provided in the second connecting pipe that connects the fluid outlet pipe and the inflow side of the economizer pipe, and a fourth on-off valve is provided between the upstream side of the third on-off valve and the inflow pipe. A cold trap device connected by a second bypass pipe. γ The vertical container has a shape in which the center of the bottom protrudes upward, and a heat pipe or blower duct is inserted into the protrusion to form a cooling section.The cold trap for low impurity concentration is equipped with a heater and blower. 7. The device according to claim 6, which has a structure.