JPH0511098A - Tritium removal method and device - Google Patents

Abstract

(57) [Summary] [Purpose] The adsorber regeneration system can be simplified and the equipment cost,
(EN) Provided are a tritium removal method and device capable of reducing the installation area, operating cost, and improving operability. [Composition] A compressor 2 for compressing a purification target gas containing tritium from a purification target 1, a reactor 6 for reacting tritium in the purified purification target gas with oxygen to form tritiated water, and a plurality of adsorbers A tritium removing device comprising an adsorber unit 8 for adsorbing and removing tritium water by switching and using 8a and 8b.
The purified gas outlet sides of the adsorber 8a, the regenerator gas supply path 20 having the heater 21, and the adsorbers 8a,
A circulation path 30 is provided on the regeneration gas outlet side of 8b to circulate to the suction side of the compressor 2 through a dehydrator including a cooler 32 and a drain 33 for cooling and dehydrating the gas after regeneration of the adsorber.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for removing tritium, and more specifically, tritium ( ³ H) is reacted with oxygen to form tritiated water ( ³ H ₂ O and ³ HHO), and the produced tritium water is The present invention relates to an adsorber regeneration system in a method and apparatus for removing tritium by using an adsorber unit that switches and uses a plurality of adsorbers.

[0002]

2. Description of the Related Art A tritium removing device is used for recovering tritium generated from a glove box for handling tritium, a glove box for biological experiments, a nuclear fusion test device, etc. so as not to be released into the atmosphere. As a method of removing tritium, generally, a method of reacting tritium with oxygen in the air using a catalyst to form tritium water, and removing the generated tritium water using an adsorbent such as a molecular sieve is a method. Has been done.

In the above method, since it is necessary to continuously remove tritium, a plurality of adsorbers of two or more are used, and one adsorber is always used for removal treatment even when another adsorber is being regenerated. It is being considered for use.

FIG. 2 shows a conventional tritium removing device. The purification target gas from the purification target 1 such as the glove box for handling tritium is first compressed by the compressor 2 and stored in the buffer tank 3. This purification target gas contains hydrogen for reducing the tritium partial pressure so that the treated gas does not exceed the legal standard value even if the concentration of tritium released from the purification target 1 is equal to or lower than a predetermined concentration. After being added from the pipe 4 as necessary, the mixture is heated to a temperature (usually about 200 ° C.) suitable for the catalytic reaction in the reactor 6 by the heater 5 and introduced into the reactor 6.
When the gas to be purified does not contain oxygen, oxygen gas is added before the reactor 6.

The tritium and the added hydrogen in the gas to be purified react with oxygen by the action of the catalyst in the reactor 6, and tritium water ( ³ H ₂ O and ³ HHO) and water (H
₂ O). Next, the gas to be purified is cooled to room temperature by the cooler 7, and then one of the adsorbers of the adsorber unit 8 that switches between the two adsorbers 8a and 8b, for example, the adsorber 8 is used.
is introduced into a. In addition, switching of the adsorbers 8a and 8b is performed by
This is performed by switching the inlet valves 9a and 9b and the outlet valves 10a and 10b to open and close.

Further, similarly to the above, even if the amount of tritium released from the purification target 1 is a predetermined upper limit value, the gas after the treatment has a legal standard value (5 × 10 ⁻³ becquerel).
Before the adsorption unit 8, a necessary amount of water for reducing the partial pressure of tritiated water is added and diluted before the adsorption unit 8 (swapping). Tritium in the water at this time is diluted to a concentration of about 1/1000 to 1/10000. However, if water is added to keep the amount of water in the air-conditioned building or glove box at a constant value, and if the tritium concentration after the adsorption process is below the legal standard value, swapping is not performed. . Also,
The same applies when the amount of added hydrogen is sufficient.

The generated tritium water and water are adsorbed and removed by an adsorbent such as a molecular sieve in the adsorber 8a. The purified gas from which tritiated water and water have been removed is led out from the outlet of the adsorber 8a, and returns to the purification target 1 through the outlet valve 10a. At this time, the dew point of the purified gas discharged from the adsorber 8a is about -65 ° C.

On the other hand, in the regeneration of the other adsorber 8b which has adsorbed the water in the previous removal step, the regeneration gas heated to about 250 ° C. by the heater 12 is introduced from the regeneration inlet valve 11b and discharged from the regeneration outlet valve 13b. It is done by doing. At this time, the regeneration inlet valve 11a and the regeneration outlet valve 1 on the side of the adsorber 8a
3 is closed, and the inlet valve 9b and the outlet valve 10b on the adsorber 8b side are also closed.

The regeneration gas containing water desorbed from the adsorbent is led out from the inlet side of the adsorber 8b through the regeneration outlet valve 13b, introduced into the cooler 14 and cooled to room temperature. Moisture (tritiated water and water) condensed by this cooling is
Recovered from drain 15. The regenerated gas, from which water has been removed to some extent, is sucked into the circulation compressor 16, compressed, and then introduced into the cold trap 17. The regeneration gas is cooled by liquid nitrogen in the cold trap 17, and the contained water is almost completely removed. The regenerated gas from which water has been removed is again introduced into the heater 12, heated and introduced into the adsorber 8b. Completion of the regeneration of the adsorber 8b is judged by the fact that the outlet temperature of the adsorber 8b being regenerated reaches the set temperature or higher and the regeneration time.

In the figure, H is the reactor 6 and the adsorber 8.
a is a heater for heating a and 8b, and C is an adsorber 8a and 8b.
The cooler which cools b is shown.

[0011]

In the tritium removing apparatus having such a structure, the tritium derived from the object to be purified is almost completely adsorbed and removed by the adsorber, and the tritium water desorbed in the regeneration process of the adsorber is also completely removed. Since the device is configured with the idea of removing it, the configuration is as described above.

That is, conventionally, for regeneration of the adsorber, a closed circulation path is formed in the flow path at the time of the regeneration process to use a dedicated regeneration gas, and two systems of a tritium removal system and an adsorber regeneration system are used. Since it has two independent circulation systems, not only is the operation complicated, but also the number of devices used in the adsorber regeneration system is large, so there is a problem that the installation area of the equipment is large and the equipment cost is high.

Therefore, an object of the present invention is to provide a tritium removing method and apparatus which can simplify the adsorber regenerating system, reduce equipment cost, installation area, operating cost and improve operability.

[0014]

In order to achieve the above-mentioned object, the method for removing tritium of the present invention is a method of removing tritium-containing gas to be purified and then heating the mixture, and then reacting it with oxygen in a reactor to prepare tritiated water. In a method for removing tritium water by adsorbing and removing tritium water by an adsorber unit that switches and uses a plurality of adsorbers, a gas to be purified is treated to regenerate the adsorber that needs to be regenerated by adsorbing the tritium water. While using a part of the purified gas derived from the adsorber outlet that is removing water, the exhaust gas derived from the adsorber after purifying the adsorber is combined with the purification target gas before the compression after dehydration treatment. It has a feature.

The tritium removing apparatus of the present invention comprises a compressor for compressing a purification target gas containing tritium, a reactor for reacting tritium in the purified purification target gas with oxygen to form tritiated water, and a plurality of reactors. In an adsorber unit for adsorbing and removing tritium water by switching and using the adsorbents, the purified gas outlet sides of the plurality of adsorbers are communicated with each other through a regeneration gas supply path having a heater. At the same time, a circulation path is provided on the regeneration gas outlet side of the adsorber to circulate the gas after regeneration of the adsorber to the suction side of the compressor via a dehydrator for dehydration treatment.

[0016]

[Operation] According to the above configuration, since a part of the purified gas derived from the outlet of another adsorber that is performing the adsorption removal process is used as the regenerated gas of the adsorber, a dedicated gas is used as the regenerated gas. There is no need to prepare. Further, since the purified gas from which water has been removed is used for regeneration, only a heater for heating the purified gas to the regeneration temperature need be installed in the regeneration system. Furthermore, the regeneration gas can be introduced only by opening and closing the regeneration valve at the same time as the valve operation for switching the adsorber for performing the adsorption removal step. In addition, since the gas containing tritium water, which is derived after the regeneration, joins the gas to be purified and is circulated, it is not necessary to completely remove the tritium water during the dehydration process, and a cold trap is also unnecessary.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail based on an embodiment shown in the drawings. The same elements as those in the conventional example are designated by the same reference numerals, and detailed description thereof will be omitted.

In the tritium removing apparatus shown in this embodiment, the tritium removing system has the same structure as the conventional tritium removing apparatus, and the purification target gas from the purification target 1 is the compressor 2 in the same manner as described above. After passing through the buffer tank 3, the heater 5, the reactor 6, and the cooler 7, the tritium contained therein and the hydrogen added from the pipe 4 are reacted to form tritium-containing water, and then the adsorber unit 8 is used for switching. The water containing tritiated water is adsorbed on the adsorbent and is removed to a dew point of −65 ° C. or lower for purification, and about 90% thereof is returned to the purification target 1.

In the adsorber regenerating system shown in the apparatus of this embodiment, the adsorber 8 and the regenerating gas supply path 20 that connects the outlets of the adsorbers 8a and 8b and the outlet valves 10a and 10b.
branch from between the inlets of a and 8b and the inlet valves 9a and 9b,
A circulation path 30 is connected between the purification target 1 and the compressor 2.

A heater 2 is provided in the regeneration gas supply path 20.
1 and regeneration valves 22a and 22b, and the circulation path 30 is provided with discharge valves 31a and 31b, a cooler 32, and a drain 33.

Here, when one of the adsorbers 8a is in the adsorption removal process and the other of the adsorbers 8b is in the regeneration process, the gas to be purified is treated to remove water containing tritiated water as described above. The inlet valve 9a and the outlet valve 10a on the side of the adsorber 8a are open, and the inlet valve 9b and the outlet valve 10b on the side of the other adsorber 8b are closed.

At this time, the regeneration valves 22a and 22b of the regeneration gas supply passage 20 and the discharge valve 31b of the circulation passage 30 are opened, and about 10% of a portion of the purified gas discharged from the outlet of the adsorber 8a, The regeneration gas of the adsorber 8b is led to the regeneration gas supply path 20 through the regeneration valve 22a. This regeneration gas is heated to a predetermined temperature in the heater 21 at about 250 ° C.
After the temperature is raised to 1, the gas is introduced into the adsorber 8b from the outlet side through the regeneration valve 22b on the adsorber 8b side, and the adsorber 8b is regenerated.

The amount of the regenerated gas is the same as that of both adsorbers 8a and 8b.
It is set so that water can be desorbed from the adsorbent and cooled to the adsorption operation temperature within the switching time of, but if the amount is small, regeneration cannot be performed sufficiently, but if the amount is too large, This is not preferable because the amount of circulating gas described below increases and the amount of gas processed by the compressor or the adsorber increases. The amount of the regeneration gas can be adjusted by providing an appropriate flow rate adjusting mechanism such as a simple orifice.

The regenerated gas (exhaust gas) containing water desorbed from the adsorbent is led out from the inlet side of the adsorber 8b and led to the circulation path 30 via the discharge valve 31b. Most of the moisture contained in this regenerated gas is condensed by being cooled by cooling water or the like in the cooler 32, and the drain 33
Recovered from. The regenerated gas with reduced water content is introduced into the suction side of the compressor 2 and circulates in the path.

During the regeneration of the adsorber 8b, the heater H attached to the adsorber 8b is operated to heat the adsorber 8b to a temperature suitable for desorption regeneration, and after the desorption regeneration is completed. Is operated by the cooler C and the regeneration gas supply path 2
The heater 21 of 0 stops operating and cools the adsorber 8b to a temperature suitable for the adsorption operation.

When the regeneration process of the adsorber 8b is completed, each valve is opened and closed in a predetermined manner, the adsorber 8b enters the adsorption removal process, and the adsorber 8a enters the regeneration process.

As described above, a part of the purified gas derived from one of the adsorbers 8a performing the adsorption removal step is used as the regenerated gas of the other adsorber 8b, whereby the regenerated gas is used. There is no need to prepare a dedicated gas, and there is no need for a circulation compressor dedicated to regenerated gas or a cold trap that requires a cryogen, and the adsorber regeneration system can be greatly simplified.

Since the burden on the compressor 2 increases by 10% due to the circulation of the regenerated gas, it is necessary to increase the capacity of the compressor 2 by about 10%. However, the compressor provided in the conventional regeneration system is The effect that can be omitted is not a big problem. Further, the amount of water in the gas to be purified increases due to the water remaining in the regenerated gas. However, as described above, when the water is insufficient, the water content for reducing the partial pressure of tritiated water is also conventionally used. May be added close to the saturated state, so there is no particular problem. However, if this water content becomes a problem, it can be easily reduced by using a refrigerator in the cooler 32.

Further, the water remaining in the regenerated gas without being condensed in the cooler 32 contains a very small amount of tritiated water, which is introduced into the adsorption removal step again by the circulation of the regenerated gas. Therefore, it is not discharged to the outside.

Further, the conventional regeneration gas completely removes water by using liquid nitrogen in a cold trap, and the regeneration gas of this embodiment uses the purified gas derived from the adsorber as it is. Therefore, the regenerated gas of this example contains a larger amount of water than before, but this regenerated gas is dehydrated by the adsorber and has a dew point of -65 ° C or lower. It can be used without any problem for the heating regeneration of.

Therefore, even if the regeneration system is configured as described above, the purified gas returning to the purification target 1 is dehydrated by the adsorber unit 8 and has a dew point of −65 ° C. or lower. The amount of tritium contained in the gas is almost the same as the conventional amount. Since the collected drain water contains a large amount of tritium water, it is stored in a predetermined facility and waits for radioactivity to decay.

[0032]

As described above, according to the present invention,
To regenerate the adsorber, which requires regeneration of the adsorber unit used in the switching system, a part of the purified gas at the adsorber outlet that processes the gas to be purified and removes water is used. Achieving a significant simplification of the regeneration system, it is possible to reduce equipment costs, installation area, operating costs, and improve operability.

[Brief description of drawings]

FIG. 1 is a system diagram of a tritium removing apparatus showing an embodiment of the present invention.

FIG. 2 is a system diagram showing an example of a conventional tritium removing device.

[Explanation of symbols]

1 ... Target of purification 2 ... Compressor 3 ... Buffer tank
5 ... Heater 6 ... Reactor 7 ... Cooler 8 ... Adsorber unit
20 ... Regeneration gas supply path 21 ... Heater 22a, 22b ... Regeneration valve 30 ... Circulation path 31a, 31b ... Discharge valve 32 ... Cooler
33 ... Drain

Claims (2)

[Claims] 1. A gas to be purified containing tritium is heated after being compressed, and reacted with oxygen in a reactor to form tritiated water,
In a method for removing tritium by adsorbing and removing the tritiated water with an adsorber unit that switches and uses a plurality of adsorbers, a gas to be purified is treated to regenerate the adsorber that needs to be regenerated by adsorbing the tritium water. Using part of the purified gas derived from the adsorber outlet that is removing tritium water, and combining the exhaust gas derived from the adsorber after purifying the adsorber with the gas to be purified before compression after dehydration treatment A method for removing tritium, comprising: 2. A compressor for compressing a gas to be purified containing tritium, a reactor for reacting tritium in the gas to be purified after compression with oxygen to form tritiated water, and a plurality of adsorbers are switched and used. In a tritium removing device provided with an adsorber unit for adsorbing and removing tritium water, the purified gas outlet sides of the plurality of adsorbers are made to communicate with each other through a regenerated gas supply path having a heater, and a regenerated gas outlet of the adsorber is provided. A tritium removal device characterized in that a circulation path is provided on the side for circulating the gas after regeneration of the adsorber to a suction side of the compressor via a dehydration device for dehydrating the gas.