JPS59202092A - Cryopump - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] 1. Technical Field of the Invention] The present invention relates to nuclear fusion reactors, etc.
11.Relates to cryopumps used for things that require qi.

[Technical Background of the Invention] A nuclear fusion reactor uses hydrogen isotopes (crude hydrogen and tritium) as fuel and generates energy and helium scum by causing a nuclear fusion reaction in a vacuum vessel. It is necessary to exhaust the residue containing hydrogen isotopes and helium remaining in the vacuum vessel (during the fusion reaction) and during combustion shutdown.

In the case of the 1- to Kamak-type fusion reactor, which is currently considered the most promising, these scum ω have a hydrogen isotope number of 3X.
10” Il+]/sec, the number of helium atoms is 1.5×
It is estimated that the number of particles per second is about 1,020, and in order to evacuate this amount, a vacuum evacuation device with the largest human capacity, such as a vacuum pump, is required. How to use it: If impurities enter the vacuum vessel of a fusion reactor, it will be difficult for the fusion reaction to occur, so the vacuum vessel must be kept clean at all times. For this reason, a cryopump is considered to be a promising vacuum pump that must also be clean.

It is known that this cryopump is used in a vacuum evacuation system for a nuclear reactor, and FIG. 1 is a diagram for explaining this. This includes a vacuum vessel 2 surrounding the fusion reactor core plasma 1, and a vacuum II-gas duct 3 that communicates with the vacuum vessel 2 to exhaust gas containing hydrogen isotopes and helium inside the vacuum vessel 2. (The vacuum evacuation tanks 1 to 3 are heated at a temperature of liquid nitrogen (77°K at atmospheric pressure) installed in the first vacuum pump chamber 5 via the gate valve 4. A chevron baffle (connected to a trap 6 of the structure) condenses and removes water vapor, etc.

Here, the chevron baffle structure is a structure in which plates (usually made of aluminum or copper) with a dogleg-shaped cross section are arranged in a sash-like manner. The evacuated gas molecules are those that can pass through the gaps between the plates.

The liquid helium temperature (4) installed in the second vacuum pump to 8 via the gate valve 7 is
, 2°K) is the surface adsorption property high? i! It has a surface such as lithium carbon and contains hydrogen isotopes and helium gas at 161%.
-C is connected to the cryo-adsorption pump 9 which adsorbs at the same time. This cryo-adsorption pump 9 has a gate valve 10. which is closed during Tono pumping. It is connected via a turbo molecular pump 11 and a rotary pump '12 to a recovery tank 13 in which hydrogen isotopes and helium are recovered in a mixed state.

As mentioned above, to describe the operation of the device made with this j:uni
) 1 gas is drawn from the inside of the vacuum container 2 through the vacuum (Jl airwaves 1 to 3) and into the 1-lap 6. , water vapor, etc. are condensed and removed, and in this state is introduced into the cryo-adsorption pump 9.The surface of the cryo-adsorption pump 9 is
Hydrogen isotopes and helium are adsorbed at the same time because the surface is coated with activated carbon, etc., which is adsorbable on the surface. The elements and helium are stored in a mixed state in the cryo-adsorption pump 9. This stored 11
When the vacuum evacuation operation is not performed, the gate valve 7 is closed and the other gate valve 10 is opened to heat and release the adsorbed II gas, and the hydrogen isotope is passed through the turbo molecular pump 11d3 and the rotary pump 12. The elements and helium are collected in a mixed state in the collection tank 13.

[Problems with technical precursors] However, since it is difficult to separate the hydrogen isotopes and helium contained in the recovered exhaust gas, hydrogen isotopes must be burned in the fusion reactor, and helium is valuable. It was difficult to utilize l\rium as a blind source, and the fuel utilization rate decreased significantly, making it extremely uneconomical.

For this reason, the above-mentioned second vacuum pump chamber 8 portion was constructed as follows in Japanese Patent Application Laid-Open No. 57-12888.
In the same container, a cryo-condensing pump is housed in the front side (gate valve 7 side) and a cryo-adsorption pump is housed in the rear side (gate valve 10 side) in No. 1. A gate valve is provided between the two to separate the two when recovering the hydrogen isotope and helium, respectively, and a hydrogen isotope recovery tank for recovering the hydrogen isotope is installed in the cryo-condensing pump. connect and
The recovery tank 13 in FIG. 1 is a helium recovery tank.

With this configuration, hydrogen isotopes and helium can be separated and recovered, and therefore they can be reused. However, since the hydrogen isotope recovery system and the helium recovery system are separate, and the Goo 1 to valves are installed in the storage container that houses the cryon condensation pump and cryo adsorption pump, the overall structure becomes a C7i doll. It is not economically favorable and there are problems in practical application.

[Purpose of the Invention] The present invention has been made in view of the above circumstances, and it is possible to collect hydrogen isotopes and helium without providing a gate valve, with only one set of hydrogen isotope and helium recovery system, and with a small size. The purpose of the present invention is to provide a lyo pump that can be separated and recovered, is easy to reuse, and is economical.

[Summary of the Invention] In order to achieve the above object, the present invention includes a case having a frontage communicating with the vacuum container formed into a box using a heat shield plate cooled with liquid nitrogen, and A chevron baffle in which a gas containing hydrogen isotopes and helium exhausted from the vacuum vessel is cooled with liquid helium, and a chevron baffle in which the gas containing hydrogen isotopes and helium exhausted from the vacuum vessel is cooled with liquid helium, and the Helium gas supply and discharge passage,
The heat shield plate is formed on the opposite side of the chevron baffle and has a helium gas adsorbent provided on the surface of the supply/discharge passage. The liquid helium supply/discharge passage is formed between the helium exhaust surface portion and the chevron baffle, and a chevron baffle is formed by making a dogleg-shaped member into a slanted cross section on the outer peripheral surface of the supply/discharge passage, and the heat shield It consists of a hydrogen exhaust surface section that is mainly used to exhaust hydrogen isotopes that are cooled by a plate.

[Embodiments of the invention] The present invention will be explained below with reference to the drawings.

First, to explain the concept of the present invention with reference to FIG. 2, 15 is a vacuum pump chamber, 16 is a W in the vacuum pump chamber 15
This is a cryopump of the present invention that has been developed. This cryopump 16 includes a helium exhaust surface 20 for mainly exhausting helium gas, a hydrogen exhaust surface 21J3 for mainly exhausting hydrogen isotopes, and a chevron baffle 22 cooled with liquid nitrogen installed on the front stage side. A case 23 made of a heat shield plate has a helium exhaust surface 20.
474 to completely surround the hydrogen exhaust 1fi721
has been completed.

Next, the cryopump 16 of the present invention is shown in FIGS. 3 to 7.
One example of this will be explained.

The helium exhaust surface 20 inside the case 23 is on the top.

A plurality of thin metal plates 201 are welded between the lower header pipes 203 and 204, and a gap is formed inside of the thin metal plates 201 through which a refrigerant such as liquid helium flows, and the outer surface of the thin metal plates 201 absorbs helium scum. @4, 4202 is configured to be bonded using an adhesive or the like.

Note that the thin metal plate 201 is made of stainless steel, aluminum, copper, or the like.

Activated carbon, molecular sieve, etc. are used as the adsorbent 202 for the helium gas, but these are adsorbent not only for general scum such as nitrogen, oxygen, and moisture, but also for hydrogen isotopes and helium gas. In the case of helium gas, it is necessary to cool down to 20° or less. In addition, a refrigerant liquid injection pipe 205 is connected to the lower header pipe 204 , and a discharge pipe 206 is connected to the upper header pipe 203 , and the refrigerant liquid such as liquid helium flows into the lower header pipe 204 through the injection pipe 205 . The helium gas flows from bottom to top through the gap between the plurality of thin metal plates 201, cools the helium exhaust surface 20, and is discharged to the outside through the vine tube 203 and the discharge tube 206. In addition, the solid line arrow in the figure shows the flow direction of the refrigerant liquid, and the broken line arrow shows the flow of liquid nitrogen.

Roughly, the hydrogen 4Jl gas 21 placed on the front stage side of the edge/cum exhaust surface 20 is connected to the upper and lower header pipes 213° 214
In between, two thin gold plates (hereinafter referred to as fins 211) per tube are placed in a ``<''-shaped cross section.
A plurality of finned tubes 212 are arranged in parallel to form a chevron baffle type. These finned tubes 212 are usually made of aluminum or copper, which has good heat conductivity. d3. The finned tube 212 is a tube made of a plurality of thin plates in the axial direction, and is manufactured by extrusion or drawing using welding or a mold.

Therefore, the lug pipe 214 to the lower part is filled with refrigerant liquid 1'.
J215 is connected, and the JJ+ outlet pipe 216 is connected to the upper header pipe 213. The refrigerant liquid passes through the injection pipe 215, flows into the lower header pipe 214, and the fins (inside the 1-shaped pipe 212 are arranged in parallel from bottom to top). The refrigerant liquid cools down to the tips of the fins 211 and is discharged from the upper header pipe 213 to the outside through the discharge pipe 216. ,As aforementioned,
Since the refrigerant flows through completely separate channels, supply and stop of the refrigerant liquid can be performed independently for each exhaust surface. The helium exhaust surface 20 and the hydrogen exhaust surface 21 are surrounded by a plurality of heat shield plates 23A cooled with liquid nitrogen in order to reduce the consumption (evaporation amount) of the refrigerant liquid due to radiant heat from the air heating section. The opening of the case 23 is completely surrounded by a chevron baffle 22 provided therein. The chevron baffle 22 is provided on the front side of the hydrogen exhaust surface 21. These heat shield plates 23A and chevron baffles 22 are provided with cooling pipes 24 without flowing liquid nitrogen, and are cooled to liquid nitrogen humidity, respectively. The heat shield plate 23A, the chevron baffle 22, and the liquid nitrogen cooling pipe 24 are usually made of a material with good thermal conductivity, such as aluminum or copper. The cryopump 16 of the invention can be suspended and supported from the ceiling (or lid) of the vacuum pump chamber 15.

In the embodiments shown in FIGS. 3 to 5 described above, all of the liquid nitrogen cooling pipes 24 are connected in series, or there is no problem even if they are divided into several parts and flowed in parallel. Also, Figure 3~
Refrigerant liquid injection pipe 205, 215 and discharge pipe 2 shown in FIG.
06 and 216 are actually the outside of the heat shield plate 23A, which has a double tube structure and is cooled with liquid nitrogen, but this is omitted here to avoid complication.

FIG. 8 shows an example of a vacuum evacuation system for a nuclear fusion reactor using the cryopump 16 of the present invention configured as described above. Number them and omit the explanation. In FIG. 8, the IJI outlet side of the rotary pump 12 is branched into two recovery lines. One is the recovery tube 30. It is connected to a helium recovery tank 32 through a gate valve 31, and the rest is connected to a recovery pipe 33. It is connected to a hydrogen 1i] 1-position element recovery tank 35 via a gate valve 34.

Hereinafter, the operation of the cryopump of the present invention will be explained based on FIGS. 2 to 8. Exhaust residue mixed with trace impurities such as hydrogen isotopes, helium, and water vapor remaining in the vacuum vessel 2 of the fusion reactor is pumped from inside the vessel 2 via vacuum exhaust ducts 1 to 3 and a gate valve 4 to a vacuum pump. It is led into the room 15. During operation of the cryopump 16, the gate valve 10 on the outlet side of the vacuum pump chamber 15 is closed, so impurities such as water vapor contained in the exhaust gas are condensed and removed by the chevron baffle 22 cooled with liquid nitrogen, and helium is removed. A mixed gas of hydrogen and hydrogen isotopes is introduced into the cryopump 16. Then, the hydrogen isotopes in the mixed residue are condensed and exhausted at the hydrogen exhaust surface 21 configured in a chevron baffle shape by a finned tube 212 cooled with a refrigerant liquid, and only the remaining helium gas flows through the gap of the hydrogen exhaust surface 21. and reaches the helium exhaust surface 20. As described above, the helium exhaust surface 20 is a thin metal plate 2 cooled by a refrigerant liquid.
Since the adsorption 4J 202 is adhered to the outer surface of 01, helium gas is adsorbed and exhausted. here? What must be kept in mind is that the hydrogen exhaust surface 21 utilizes the condensation exhaust effect of a metal surface cooled with a refrigerant liquid. Therefore, although it is effective against hydrogen isotopes and gases other than helium, it is completely ineffective against helium gas. Since it utilizes action, it is effective against both helium scum and hydrogen isotopes.

Therefore, if the order of the hydrogen exhaust surface 21 and the helium exhaust surface 20 is reversed, hydrogen isotopes will be adsorbed and exhausted together with helium gas on the helium exhaust surface 20, so that when regenerating the cryopump, which will be described later, the helium gas and Separation and recovery of hydrogen isotopes becomes impossible. Since the hydrogen exhaust surface 21 and the helium exhaust surface 20 are storage type pumps that store hydrogen isotopes and helium gas, respectively, the gas molecules stored on each exhaust surface can be released during shutdown of the fusion reactor. Is it necessary to drain the water to the outside using another vacuum pump?

Hereinafter, this will be referred to as "regeneration of the cryopump (or each exhaust surface)."

When regenerating the cryopump of the present invention, it is necessary to regenerate the helium exhaust surface 20 first, so first, the gate valve 4 on the inlet side of the vacuum pump chamber 15 is closed, and the gate valve 10 on the outlet side Open the gate valve 31 and connect the recovery line on the discharge side of the rotary pump 12 to the helium recovery tank 32.

(This Il!J gate valve 34 is fully opened.) Then, the supply of refrigerant liquid to the helium exhaust surface 20 is stopped, and the
For example, when liquid helium is used as the refrigerant liquid, helium gas is injected from the outside through the injection pipe 205 and the helium exhaust surface 205 is heated.
The helium exhaust surface 20 is heated to about 20 to 30' by flowing out through the exhaust pipe 206, and the helium gas adsorbed on the helium exhaust surface 2o is separated (released). let The released helium gas is
It is evacuated by the turbo molecular pump 11 and the rotary pump 12 and recovered into the helium recovery tank 32. At this time, since the refrigerant liquid continues to be supplied to the hydrogen exhaust surface 21, there is no hydrogen isotope condensed and exhausted to the hydrogen exhaust surface 21.

When most of the helium gas adsorbed on the helium exhaust surface 20 is recovered, the gate valve 31 is closed, the other gate valve 34 is opened, and the output side of the rotary pump 12 is recovered. line to hydrogen isotope recovery tank 3
Connect to 5. Then, as in the previous book, the supply of refrigerant liquid to the hydrogen JJl gas surface 21 is stopped, and refrigerant gas whose temperature is controlled at about 20 to 30' is injected from the outside through the injection pipe 215, and the hydrogen is exhausted. Passing through the surface 21, a discharge pipe 216
By flowing out to the outside through the hydrogen exhaust m1
21 to about 20 to 30', and remove the hydrogen isotope condensed on the hydrogen exhaust surface 21. Then, remove the hydrogen isotope from the turbo molecular pump 11 and the rotary pump 12. The hydrogen isotope is exhausted and recovered in the hydrogen isotope recovery tank 35. When regenerating the hydrogen exhaust surface 21, the helium exhaust surface is 20 temperature to 1
It is necessary to raise the value to around 00'. In this case also 1
The helium exhaust surface 2o can be heated by injecting refrigerant gas whose temperature is controlled to about 00' from the outside through the injection port 205.

In this way, there is no need to provide a gate valve unlike in the past, and there is no need to separate recovery systems for hydrogen isotopes and helium, so the system is compact and economically advantageous. In addition, since hydrogen isotopes and helium gas can be separated and recovered, hydrogen isotopes can be recovered from the combustion of nuclear fusion reactors.
``Helium gas can be reused as a valuable helium resource.'' After the regeneration of each exhaust surface is completed, refrigerant liquid is supplied to each exhaust surface again to cool each exhaust surface to around the liquid helium temperature (462°K).

Then, the gate valve 1° on the outlet side of the vacuum pump chamber 15 is connected to IWj.
Then, open the gate valve 4 on the inlet side and restart the operation of the cryopump 1G.

When regenerating the cryopump 16, if the hydrogen exhaust surface 21 is heated first, the released hydrogen isotopes will be adsorbed on the helium exhaust surface 2o, so when the helium exhaust surface 20 is regenerated, the hydrogen isotopes will be mixed with helium gas. Separation and recovery of elements becomes impossible.

Figures 9 to 12 show helium exhaust surface 2o and hydrogen 1-1
This is an example in which jJl can be applied from both sides in order to increase the area of Qi 21. Since the configuration and operation of the equipment are almost the same as described above, the same reference numerals as in FIGS. 3 to 7 are used to omit the explanation. In this example C', the hydrogen exhaust surface 21
are on both sides, the injection pipe 215 and extraction pipe 216 are branched into two in the middle, that is, the branch pipe 21 of the injection pipe
5a, 215b and branch pipes 216a, 21 of 1/1 outlet pipe
Only 6b is different.

[Effect of the invention 1 As described above, according to the present invention, the helium exhaust surface is adsorbed (A) on a metal surface cooled with a refrigerant liquid such as liquid helium, and a tube cooled with a refrigerant liquid is attached to the front side of the helium exhaust surface. It consists of a case consisting of a plurality of heat shield plates cooled with liquid nitrogen and a chevron baffle surrounding the helium exhaust surface and hydrogen exhaust surface arranged in a chevron baffle shape. By installing the refrigerant liquid injection pipe and discharge pipe to the air surface independently, it is compact and economical. Helium gas and hydrogen isotopes can be heated independently, making it possible to separate and recover helium gas and hydrogen isotopes. Hydrogen isotopes can be used as fuel for nuclear fusion reactors, and helium gas can be recycled as a valuable helium resource. We can provide cryopumps that can be used.

[Brief explanation of the drawing]

Figure 1 is a diagram showing a conventional vacuum evacuation system widely used in nuclear fusion reactors, Figure 2 is a diagram showing the concept of the cryopump of the present invention, and Figure 3 is an illustration of a cryopump of the present invention. 4 is a cross-sectional view taken along line A-A in FIG. 3 and viewed in the direction of the arrow; FIG. 5 is a cross-sectional view taken along line A-A in FIG. 3;
6 is a cross-sectional view cut along line B and viewed in the direction of the arrow, Figure 6 is a cross-sectional view taken along line C-C in Figure 4, and Figure 7 is a cross-sectional view taken along line D-D in Figure 4 and viewed in the direction of the arrow. 8 is a diagram showing an example of using the cryopump of the present invention in a vacuum evacuation device for a nuclear fusion reactor, and FIGS. 9 to 12 are diagrams showing other embodiments of the present invention. 9 is a sectional view taken along line A'-A' in FIG. 10 and viewed in the direction of the arrow, and FIG. 10 is a cross-sectional view of B r in FIG. 9.
13 Figure 11 is a cross-sectional view of the IJ cut along the + line and viewed in the arrow direction, Figure 11 is a sectional view taken along the E-F line in Figure 10 and viewed in the arrow direction. It is a sectional view taken along the line FF and taken in the direction of the arrow. DESCRIPTION OF SYMBOLS 1... Core Bushizuma, 2... Vacuum vessel, 3... Vacuum exhaust duct, 4, 10... Gate valve, 11... Turbo molecular pump, 12... Rotary pump, 15...
Central air pump room, 16...Cryopump, 2o...
Helium exhaust surface, 21... Hydrogen exhaust surface, 22... Chevron baffle, 23... Case, 23A... Heat shield plate, 24... Liquid nitrogen cold IJ pipe, 25...
・Hanging pole 1~. 201... Metal thin plate, 202...
・Adsorbent, 211...fin, 212...fin f
q pipe, 203, 213... Upper header pipe, 204
．． 214...lower header pipe, 205.21b...
Refrigerant liquid injection pipe, 2o6°216...extraction pipe, 30.
33... Recovery pipe, 31° 34... Gate valve, 32...
・Helium recovery tank, 35...Hydrogen isotope recovery tank. 1st Weak 21 1 Figure 3 Figure 4 Figure 5 Figure 6 - Figure 8 Figure 9

Claims (4)

[Claims] (1) Gas containing hydrogen isotopes and helium is transferred from inside the vacuum vessel to a nuclear fusion reactor that causes a nuclear fusion reaction using hydrogen isotopes as fuel to generate energy and helium gas from inside the vacuum vessel. A cryopump for exhausting air from inside a container includes a case having a box-shaped opening that communicates with the vacuum container using a heat shield cooled with liquid nitrogen, and an RJi surface provided at the opening of this case. The helium is cooled by the helium, and the helium is cooled by the helium. J) Connect one passage to the chevron baffle and the other.
1!11, and a helium exhaust surface part for exhausting the helium gas as soil after being cooled by the heat shield plate installed on the surface of the oil passage (1) l' oil passage surface (this helium gas 1νk). , the liquid helium supply/discharge passage is formed in the case between the helium 1) 1 air surface portion and the chevron baffle, and a dogleg-shaped member in cross section is arranged on the outer peripheral surface of the supply υ1 passage to form a shear [ 1. A cryopump comprising: a water pipe forming a lance huffle and exhausting mainly hydrogen isotopes cooled by the heat shield plate; and an exhaust surface part. (2) The cryopump according to claim (1), wherein a refrigerant injection path and a υ1 outlet path are independently formed in the helium exhaust surface portion and the hydrogen exhaust surface portion, respectively. (3) Regenerating the helium exhaust surface and the hydrogen exhaust surface Apply 11 (1 liter) of uFf to each exhaust surface and 8 tl' independently.
7. The cryopump according to claim (1), wherein a refrigerant that can be well controlled is supplied from the outside through an injection pipe. (4) The cryopump according to claim 1, wherein the helium exhaust surface portion and the hydrogen exhaust surface portion are formed in multiple layers.