JPH01115808A - Rare gas recover device - Google Patents

Abstract

PURPOSE:To control temperature in an active carbon column in high accuracy, by connecting an electric wiring for controlling a heater introduced into a heat insulating container while sandwiching an oxide superconductor arranged in the active carbon column in between the electric wiring. CONSTITUTION:An electric current is sent to a heater electric source wiring 16 to heat the a heater 11 and the temperature of an active carbon column 2 put in a heat insulating container 1 is raised. When a heat transition temperature is reached, an oxide superconductor 15 is transferred to a dielectric material to stop electric current to the heater 11. Simultaneously, a solenoid valve 13 is opened by a relay 17, liquid nitrogen is sprayed from a spray nozzle 5 in the container 1, temperature outside the active carbon cylinder 2 is reduced to prevent overshoot of temperature in the active carbon column 2. Temperature in the active carbon column 2 is lowered with reduction in temperature outside the active carbon cylinder 2 and electric current is resent to the heater 11 to heat the active carbon column at <=the transition temperature.

Description

Detailed Description of the Invention [Objective of the Invention] (Industrial Application Field) The present invention is a method for deep cooling low-concentration radioactive noble gases used in the failed fuel detection system of fast breeder reactors (FBRs) using activated carbon. The present invention relates to a rare gas recovery device suitable for an analysis device that adsorbs and concentrates the gas and analyzes its components.

(Prior Art) A rare gas recovery device is used in a failed fuel position detection device for a fast breeder reactor. This rare gas recovery device uses a low concentration mixed rare gas (e.g. xenon, krypton) contained in the carrier gas, argon gas, which contains radioactive substances.
The isotope of -18
After being adsorbed and concentrated by an adsorption method using activated carbon at an extremely low temperature of 0° C., the next step is to heat it to desorb the rare gas, and then send it to an analyzer to analyze the components of the rare gas.

Next, a conventional rare gas recovery apparatus will be explained with reference to FIG.

As shown in the figure, the rare gas recovery apparatus is roughly divided into a rare gas adsorption system A, a liquid nitrogen supply system B, and a detection control C.

First, a detailed diagram of the rare gas adsorption system A will be explained with reference to FIG. A thermocouple 4 detects the temperature of the heat exchanger tube 3 for heating or cooling the activated carbon cylinder 2 and activated carbon cylinder 2.
The spray nozzle 5 is arranged above the spray nozzle 5.

The upper opening of the heat insulating container 1 is hermetically closed with a lid 7 having a heat insulating material 6 on the lower surface, and the lid 7 has a nitrogen gas outlet pipe 8. Processed gas inlet pipe 9. An outlet pipe 10 and a rod-shaped electric heater 11 are attached.

Further, the spray nozzle 5 is connected to a liquid nitrogen inlet pipe 12, and a number of nozzle holes are formed on the lower surface thereof.

By the way, when cooling the activated carbon cylinder 2, as shown in FIG. 5, the solenoid valve 13 of the liquid nitrogen supply system B is opened, liquid nitrogen is introduced from the liquid nitrogen cylinder 14, and is sprayed from the spray nozzle 5 to completely fill the inside of the container. Cool to 180°C. And-
After reaching 180°C, liquid nitrogen is intermittently supplied to maintain the temperature for 5 to 6 hours. The liquid nitrogen that has flowed in is vaporized and flows out from the outlet pipe 8 as nitrogen gas.

On the other hand, the activated carbon cylinder 2 is heated by the heat generated by the electric heater 11 by connecting it to a power source.

Heating is carried out in two stages; in the first stage, the temperature is raised to a temperature where only the co-adsorbed carrier gas is desorbed and no noble gas is desorbed; then, the co-adsorbed carrier gas is removed while keeping the temperature constant; In the second stage, the temperature is raised to an even higher temperature to desorb the concentrated rare gas.

An example of the above operation pattern is shown in FIG.

In FIG. 4, the vertical axis indicates the activated carbon temperature, and the horizontal axis indicates time, where ■ indicates rare gas and carrier gas adsorption, ■ indicates carrier gas desorption, and ■ indicates regeneration state.

(Problem to be solved by the invention) During heating, especially in the first stage, only the co-adsorbed gas is released and no noble gas is released, so it is necessary to maintain a temperature of about -80°C. It is necessary to alternately perform heating with the heater 11 and cooling with liquid nitrogen.

This control is performed using a temperature signal from a thermocouple, but when the thermocouple 4 is attached to the outer wall of the activated carbon section, it is easily affected by heater radiation and liquid nitrogen droplets, so it is difficult to control with high precision without heat. It is necessary to insert the pair into the activated carbon cylinder. However, in that case, in order to accurately measure temperature with a sheathed thermocouple, the insertion dimension is generally 20 times or more the outer diameter of the thermocouple, so to prevent the activated carbon tube 2 from becoming larger, the diameter of the thermocouple should be reduced. It is necessary to make the wire thinner, which may cause problems such as wire breakage.
Another drawback is that the mounting method is complicated.

Furthermore, controlling the heater and liquid nitrogen supply valve B using temperature signals requires instrumentation and control equipment such as a transmitter, amplifier, controller, and panel, making the cost of rare gas recovery equipment high. .

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide a rare gas recovery device that has a simple structure, high control accuracy, and is inexpensive.

[Structure of the invention]

(Means for Solving the Problems) In order to solve the above problems, the present invention does not use a temperature sensor for controlling the heater, but connects electrical wiring for controlling the heater to an activated carbon tube introduced into a heat insulating container. Connect by sandwiching the oxide superconductor placed inside.

This wiring may be a heater power supply wiring directly connected to the heater.

Further, the control wiring of this liquid nitrogen supply solenoid valve is provided with a relay whose circuit is open when the heater wiring is energized and whose circuit is closed when the heater wiring is not energized.

(Function) The effect of the above means is due to the characteristics of the oxide superconductor; when the oxide superconductor in the activated carbon cylinder reaches a transition temperature or higher during heating, its resistance increases rapidly and it becomes an insulator. energization to the heater is stopped. At the same time, the relay circuit opens the liquid nitrogen supply solenoid valve, and liquid nitrogen is supplied into the container, lowering the activated carbon cylinder temperature and suppressing cylinder temperature overshoot.

When the temperature inside the cylinder falls below the transition temperature due to cooling with liquid nitrogen, the resistance of the oxide superconductor becomes 0, and the heater is energized.
At the same time, the supply of liquid nitrogen stops.

By repeating this process, the temperature inside the activated carbon cylinder can be kept constant, and no special control device is required.

In addition, since the oxide superconductor does not generate heat when energized, there is no risk of heating the inside of the cylinder from the inside and causing unstable control due to a rapid temperature rise.

(Embodiment) An embodiment of the rare gas recovery apparatus according to the present invention will be described below with reference to FIGS. 1 to 3. Note that the same parts in the figure as in FIGS. 5 and 6 are indicated by the same reference numerals, and the explanation of the overlapping parts will be omitted. The difference between the present invention and the conventional example is that in FIG. 1, (15) is an oxide superconductor provided in the activated carbon cylinder (2), and the heater power supply wiring (16) that supplies current to the electric heater (11). is introduced into the heat insulating container ω and connected to the electric heater 11 via this oxide superconductor (15).

Further, a relay (17) is provided which opens when the heater power supply wiring (16) is energized and closes solenoidally, and is connected to the solenoid valve (13). Other system configurations are the same as those shown in FIG.

Figure 2 shows the specific structure of the rare gas recovery system (A).
An example of the arrangement of 5) is shown in FIG. 3(a). That is, Fig. 3 (a
), the first oxide superconductor (15a) is formed in the shape of a rod, band, or line, and is arranged on the gas outlet side. or,
(18) is activated carbon.

Next, the effect will be explained. When a current is passed through the heater power supply wiring (16) and the heater (11) is heated from the state shown in Figure 4 (■), the temperature of the activated carbon cylinder (■) rises, and when it eventually reaches the transition temperature, it becomes an oxide superconductor (I5). is transferred to the insulator, and power supply to the heater (11) is stopped. Since this transition temperature varies depending on the composition of the oxide superconductor (15), the one most suitable for control is selected.

At the same time as the heater (11) is turned off, the solenoid valve (13) is opened by the action of the relay (17), and liquid nitrogen is sprayed from the spray nozzle (c) into the heat insulating container ω, reducing the temperature rise in the activated carbon cylinder. By this, overshoot of the temperature inside the activated carbon cylinder is suppressed.

Afterwards, as the temperature outside the activated carbon cylinder decreases with liquid nitrogen,
When the temperature inside the activated carbon tower (1) also decreases and becomes below the transition temperature, the heater (11) is energized again and heating begins.

By repeating this process, the inside of the activated carbon cylinder (2) is kept at a constant temperature as shown in Figure 4 (2).

Further, since the oxide superconductor (15) does not generate heat when the heater is energized, heating is performed only by the external heater (11), and the temperature can be stably maintained at a low temperature of about -80°C.

Heating to the state shown in FIG. 4m is performed by using oxide superconductors having different transition temperatures, or by supplying current to the heater in a separate circuit that does not go through the oxide superconductor. In the latter case, control is by a temperature detector, but since the state shown in Figure 4 (m) is a desorption process of a rare gas that has already been condensed, highly accurate control is not necessary, and the temperature detector is installed on the outer wall of the activated carbon cylinder. Easy to install,
Further, the controller may be a temperature switch, and furthermore, liquid nitrogen control is not necessary at this stage.

According to the above embodiment, the temperature inside the activated carbon cylinder can be controlled with high precision with a simple structure without increasing the size of the activated carbon cylinder, and the control device can be made into an FF1 element. In addition, since the characteristics of the oxide superconductor itself are utilized, reliability is high and there is no heat generation, so there is no risk of wire breakage.

Other examples of arrangement of oxide superconductors are shown in FIGS. 3(b) to 3(d).

FIG. 3(b) shows a second rod-shaped oxide superconductor (15b) inserted into an activated carbon layer, which has the effect of being able to be controlled by the temperature of the activated carbon layer itself.

Figure 3 (C) shows a ring-shaped coating of the third oxide superconductor (15c) on the inner wall of the activated carbon tower.
The fluid resistance inside the cylinder 2 can be reduced and the cross-sectional area can be increased, so a large current can flow. Note that (19) is an electrical insulator.

In FIG. 3(d), the fourth oxide superconductor (15d) is molded directly as a part of the container, and a larger current can be passed through it than in FIG. 3(C).

In the above embodiment, the heater power supply wiring was directly connected to the oxide superconductor, but the same operation and effect can be obtained by, for example, providing a switch in the middle of the heater power supply wiring and connecting the control wiring for operating this switch to the superconductor. can get.

〔Effect of the invention〕

According to the present invention, highly accurate activated carbon cylinder temperature control can be realized with a simple structure without using a special control device, and an inexpensive and highly reliable rare gas recovery device can be provided.

[Brief explanation of the drawing]

FIG. 1 is a schematic system diagram showing an embodiment of a rare gas recovery apparatus according to the present invention, and FIG. 2 is a vertical sectional view schematically showing a part of the rare gas adsorption system in FIG. 1 on an enlarged scale. Figures 3 (a), (b), (c), and (d) are longitudinal cross-sectional views showing examples of the arrangement of oxide superconductors in the liquid nitrogen supply system in Figure 1, and Figure 4 is a diagram showing examples of the arrangement of oxide superconductors in the liquid nitrogen supply system in Figure 1. A characteristic diagram showing an example of an operation pattern of the recovery device, FIG. 5 is a schematic system diagram showing a conventional rare gas recovery device, and FIG. 6 is a longitudinal sectional view showing a conventional rare gas recovery system. A...Rare gas adsorption system B...Liquid nitrogen supply system C
...Detection control system 1...Insulating container 2...Activated carbon cylinder 3...Heat transfer tube 4...Thermocouple
5...Spray nozzle 6...Insulating material
7... Lid 8... Nitrogen gas outlet pipe 9... Processed gas inlet pipe 10... Processed gas outlet pipe 11...
・Electric heater 12...Liquid nitrogen inlet pipe 13...
Solenoid valve 14...Liquid nitrogen cylinder 15...Oxide superconductor 16...Heater power supply wiring 17...Relay 18...Activated carbon 19...Electric insulator agent Patent attorney Yudo Nori Chika Kendai Daikomaru Figure 1 Figure 2 Figure I Figure 4 Figure 5 Figure 6

Claims (4)

[Claims] (1) An activated carbon cylinder through which a gas to be treated containing a rare gas flows in and out is housed in an insulated container, and within the insulated container, a spray nozzle and a heater for supplying liquid nitrogen into the container are installed around the activated carbon cylinder. In the rare gas recovery device placed in the rare gas recovery device, an electric wiring used for controlling energization of the heater is introduced into a container and connected through an oxide superconductor placed in the container. Noble gas recovery equipment. (2) The wiring used to control the energization of the heater is
2. The rare gas recovery device according to claim 1, wherein the rare gas recovery device is a heater power supply wiring. (3) The rare gas recovery device according to claim 1, wherein the oxide superconductor is disposed within an activated carbon cylinder. (4) The rare gas recovery device according to claim 1, wherein the oxide superconductor forms a part of an activated carbon cylindrical container.