JP3743777B2 - Vacuum pumping system for nuclear fusion equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vacuum exhaust system for a large magnetic confinement fusion reactor.
[0002]
[Prior art]
As a fusion technology currently being studied, a magnetic confinement type fusion reactor that generates plasma in an annular vacuum vessel and raises the density of the plasma with an electromagnet around the vacuum vessel to cause fusion. There is.
[0003]
Conventionally, as a vacuum exhaust system from a vacuum vessel of a large nuclear fusion reactor, a mechanical pump system including a turbo molecular pump a as shown in FIG. 2 or a helical groove vacuum pump b is used as a main pump, A system comprising a vacuum pump system using a cryopump c as shown in FIG. 3 as a main pump is known.
[0004]
Here, d is a switching valve, e is a backing pump for assisting the main pump, and f is a half of a vertical section of the annular vacuum vessel. An arrow X indicates the discharge direction of the conduit for discharging tritium to the tritium treatment system.
[0005]
[Problems to be solved by the invention]
The magnetic confinement fusion device has a high magnetic field area. If a mechanical pump system such as a turbo molecular pump or a helical groove vacuum pump is operated in this high magnetic field area, problems such as heat generation may occur in the rotating part of these pump systems. There was a problem that occurred.
[0006]
For this reason, the mechanical pump system must be installed at a sufficient distance from the vacuum vessel in the core, and a strict magnetic shield must be applied to the mechanical pump system.
[0007]
However, if the distance between the vacuum vessel and the mechanical pump system is set apart in this way, the pressure loss in the connection pipes of both of these will increase, and therefore the pipe diameter of the connection pipe will be increased, If the pumping speed of the mechanical pump system is not increased, the pumping speed required by the vacuum vessel cannot be secured.
[0008]
Furthermore, in the case of the above-described mechanical pump system, there is a problem that dust may accumulate in the gap between the rotating part and the stationary part of the pump and cause a failure.
[0009]
On the other hand, in a vacuum pump system using a cryopump as the main pump, the cryopump can be installed near the vacuum vessel in the high magnetic field area, and the pressure loss in the pipe can be shortened by shortening the connecting pipe between the two. Can be reduced.
[0010]
However, since this cryopump is a reservoir type pump that traps and exhausts gas on the cryopanel surface by adhesion or adsorption, it cannot be continuously exhausted, and operation is stopped halfway. It is necessary to regenerate the cryopanel surface.
[0011]
However, in a fusion reactor that operates continuously, interruption of exhaust from the vacuum vessel is not allowed, so it is necessary to connect a plurality of cryopumps in parallel to the vacuum vessel and alternately repeat exhaust and regeneration operations.
[0012]
In the regeneration operation of this cryopump, the temperature of the cryopanel is raised to vaporize and release the adhering material, and the cryopanel is cooled again. It takes a lot of time to raise and recool the cryopanel. Therefore, a large number of cryopumps are required for continuous exhaust of the vacuum vessel, and at the same time, the same number of switching vacuum valves as these cryopumps are required.
[0013]
In this way, the vacuum pump system that uses the cryopump as the main pump has a huge amount of equipment, and the cryopump has a very large amount of dangerous tritium retention, which requires strict safety measures. have.
[0014]
An object of the present invention is to solve these problems, and to provide a vacuum evacuation system for a nuclear fusion apparatus which is short in piping from a vacuum vessel and is excellent in terms of economy, safety and reliability. .
[0015]
[Means for Solving the Problems]
The present invention to achieve the above object, the gas recovery apparatus for recovering the gas that drives the Rutotomoni the ejector comprises an ejector which is driven by an inert gas inside the high magnetic field area border fusion device Installed on the exhaust side of the ejector, a recycling circuit for reusing the gas recovered by the gas recovery device for driving the ejector, and a backing pump system comprising a mechanical vacuum pump in the gas recovery device It is characterized by being attached .
[0016]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to FIG.
[0017]
FIG. 1 is a system diagram of a vacuum evacuation system of a nuclear fusion apparatus according to the present invention, and a hydrogen isotope, helium and impurities are contained in an annular vacuum vessel 1.
[0018]
The ejector 2 is installed near the vacuum vessel 1 and connected to the vacuum vessel 1 through a short pipe 3a.
[0019]
In addition, 1a shows the high magnetic field area | region boundary of a nuclear fusion apparatus, and this ejector 2 is installed inside this high magnetic field area | region boundary 1a.
[0020]
In the present embodiment, argon gas is used as the drive gas for the ejector 2, and 3 b indicates an argon gas supply line for driving the ejector 2.
[0021]
The pipe 3c on the exhaust side of the ejector 2 is branched into two, one of the branches is connected to the gas recovery device 5a via the switching on-off valve 4a, and the other branch is connected to the switching on-off valve 4b. To the gas recovery device 5b. Each of these gas recovery devices 5a and 5b includes an argon trap 5d or 5f having a heat exchange part 5c or 5e therein. In addition, 5g shows a pressure gauge.
[0022]
The piping 3d connected to the gas recovery device 5a is connected to the piping 3f via the on-off valve 4d, and the piping 3e connected to the gas recovery device 5b is connected to the piping 3f via the on-off valve 4e. These form an argon gas recycling circuit 3.
[0023]
For the argon traps 5d and 5f, a porous sorbent cooled to about 80 ° K., in particular, molecular sieve, activated alumina, activated carbon, etc. that easily collect argon and impurities are used. It is also possible to form an argon trap using a metal surface cooled to 30 degrees K or less.
[0024]
These argon traps are cooled by passing a refrigerant through the heat exchange parts 5c and 5e. In addition, these also function as an evaporator by letting a heat medium pass through the heat exchange parts 5c and 5e.
[0025]
Next, the gas recovery devices 5a and 5b are each connected to one pipe 3h via an on-off valve 4f or 4g, and the pipe 3h is further connected to a backing pump system 6. The backing pump system 6 is composed of any one of a mechanical vacuum pump such as a turbo molecular pump, a helical groove vacuum pump, a composite molecular pump, or a combination of these mechanical vacuum pumps.
[0026]
Since the backing pump system 6 is installed outside the high magnetic field zone boundary 1a, the rotating part of the mechanical vacuum pump constituting the backing pump system 6 may cause problems such as heat generation due to the high magnetic field. There is no.
[0027]
In addition, in this way, on the pipes connected to the gas recovery devices 5a and 5b, on-off valves 4a, 4d and 4f or on-off valves 4b, 4e and 4g are installed, respectively. Each pipe is formed so as to be able to block conduction.
[0028]
An arrow Y indicates the discharge direction of the exhaust from the backing pump system 6.
[0029]
Reference numeral 3g denotes an argon gas supply source pipe, and 4c denotes the argon gas supply control valve. In addition, 3k shows a pressure gauge.
[0030]
Next, the operation of the present embodiment will be described.
[0031]
Supplying A argon gas to the ejector 2 from the argon gas supply line 3b, the gas in the vacuum chamber 1 and the pipe 3a is discharged by the action of the ejector 2.
[0032]
When the pressure in the pipe 3a is 3 to 4 Pa, the pressure in the pipe 3c on the exhaust side of the ejector 2 is about 50 to 70 Pa. The exhaust gas in the pipe 3c is discharged from the vacuum vessel 1 together with the argon gas. Consists of discharged hydrogen isotopes, helium and impurities.
[0033]
The exhaust gas is sucked by the backing pump system 6 and guided to either the gas recovery device 5a or 5b.
[0034]
In the example of FIG. 1, the on-off valves 4b and 4g are opened and the exhaust gas is conducted to the gas recovery device 5b. The gas recovery device 5a closes the on-off valves 4a and 4f to shut off the introduction of the exhaust gas. . The argon trap 5f provided in the gas recovery device 5b is cooled to an ultra-low temperature.
[0035]
The exhaust gas flowing into the gas recovery device 5b is trapped by the argon trap 5f by solidifying and trapping argon gas and impurities, and only the hydrogen isotope and helium are exhausted in the arrow Y direction through the backing pump 6. .
[0036]
In this way, while the argon trap 5f of the gas recovery device 5b is capturing the argon gas and impurities, the gas recovery device 5a regenerates the argon trap 5d.
[0037]
That is, the heat exchange unit 5c through the heat transfer medium instead of the refrigerant is made to function argon trap 5d as an evaporator, it is vaporized argon gas previously argon trap 5d is trapped through the A argon gas recycling circuit 3 argon gas supply It is made to reflux to the pipe line 3b.
[0038]
Note that the reflux pressure of the argon gas needs to be adjusted so as to maintain the pressure necessary for driving the ejector 2 (indicated by the pressure gauge 3k ). For this reason, the supply amount of the heat medium to the heat exchange unit 5c is controlled to control the evaporation amount of the argon gas from the argon trap 5d, and the pressure in the gas recovery device 5a (indicated by the pressure gauge 5g) is adjusted. Like to do.
[0039]
In this way, the argon gas is recovered simultaneously with the regeneration of the argon trap 5d.
[0040]
It should be noted that impurities such as dust are removed by being accumulated on the argon trap 5f .
[0041]
Eventually, if the argon gas trapping capacity of the argon trap 5f of the gas recovery device 5b decreases, the introduction of the exhaust gas from the pipe 3c is switched to the gas recovery device 5a, and the gas recovery device 5b The introduction of the exhaust gas is shut off, and the regeneration operation of the argon trap 5f is started.
[0042]
In FIG. 1, the open / close valves 4a, 4e, and 4f painted black are in a closed state, and the open / close valves 4b, 4d, and 4g that are not filled are in an open state.
[0043]
In this way, the vacuum exhaust system can be operated continuously by alternately repeating the above-described argon gas capturing and regeneration operations periodically in the two sets of gas recovery devices 5a and 5b.
[0044]
Further, since the exhaust gas passing through the backing pump system 6 has already been freed of the argon gas, the load on the backing pump system 6 can be reduced.
[0045]
Note that two or more gas recovery devices may be provided in order to allow the exhaust system to work continuously in consideration of the time required for precooling and preheating during regeneration of the argon trap. In addition to argon, any of neon, krypton, xenon, or a mixed gas thereof may be used as the ejector driving gas.
[0046]
In the present embodiment, in order to make the argon trap 5d or 5f function as an evaporator, a heat medium is passed through the heat exchanging section 5c or 5e. The argon trap may be heated, or the heated argon gas may be introduced into the gas recovery device 5a or 5b to heat the argon trap.
[0047]
【The invention's effect】
As described above, according to the present invention, the ejector driven by the inert gas is installed in the high magnetic field area of the nuclear fusion apparatus so as to exhaust from the vacuum vessel. It is possible to simplify the incidental equipment, etc., and the installation space in the high magnetic field area is small, and since the ejector has no mechanical moving parts, failure or performance deterioration due to dust from the vacuum vessel or high-temperature intake gas The dust is carried on the ejector driving gas and accumulated in the gas recovery device, so that the processing is easy. Further, the suction gas mainly composed of a hydrogen isotope from the vacuum vessel is ejected. It is diluted with an inert gas, which is a driving gas, so that there is no danger of explosion and safety is increased.
[Brief description of the drawings]
FIG. 1 is a system diagram of an embodiment of a vacuum evacuation system of a fusion apparatus according to the present invention.
FIG. 2 is a system diagram of a vacuum evacuation system of a conventional fusion apparatus using a mechanical pump system as a main pump.
FIG. 3 is a system diagram of a vacuum evacuation system of a conventional fusion apparatus using a cryopump as a main pump.
[Explanation of symbols]
1a High magnetic field zone boundary 2 Ejector 3 Reuse circuit
3k pressure gauge 4a, 4b, 4d, 4e, 4f, 4g On-off valve 5a, 5b Gas recovery device 5c, 5e Heat exchange part 5d, 5f Gas trap 5g Pressure gauge 6 Backing pump system

Claims (3)

The gas recovery apparatus for recovering the gas that drives the Rutotomoni the ejector comprises an ejector which is driven by an inert gas inside the high magnetic field area border of the nuclear fusion device is installed on the exhaust side of the ejector, the gas recovery A fusion circuit comprising: a recycling circuit for reusing the gas recovered by the apparatus for driving the ejector; and a backing pump system comprising a mechanical vacuum pump attached to the gas recovery apparatus. Vacuum exhaust system. 2. The fusion device according to claim 1, wherein the backing pump system includes any one of a mechanical vacuum pump such as a turbo molecular pump, a helical groove vacuum pump, and a composite molecular pump, or a combination thereof. Vacuum exhaust system. 2. The vacuum exhaust of a nuclear fusion apparatus according to claim 1 , wherein the inert gas used to drive the ejector is argon, neon, krypton, xenon, or a mixed gas thereof. system.

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