JPS595798B2 - Cryopump regeneration device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cryopump regeneration device used in a vacuum pumping system whose main purpose is to pump out hydrogen, deuterium, tritium, or the like.

When this type of cryopump is regenerated, a large amount of hydrogen-based gas and a relatively small amount of mixed gas such as oxygen, nitrogen, water vapor, and carbon compound gas are released from the cryopump.

Therefore, the regeneration exhaust pump system needs to be divided into parts having the following two functions.

In other words, (1) a metal compound assembly with a large absorption capacity for hydrogen-based gases, whose operating conditions are set to selectively absorb it, and (2) a relatively small-capacity assembly for discharging gases other than hydrogen-based gases. Vacuum pump system, Conventional hydrogen-based gases such as hydrogen, deuterium, and tritium, especially when handling tritium, cannot be used to discharge dangerous tritium into the atmosphere during regeneration with only the 2-ion pump, so tritium treatment is necessary. was encountering difficulties.

Based on the above-mentioned knowledge, the present inventor separated the hydrogen absorbers d 1 , d 2 . The purpose of this system is to refill the cryopump material or regenerated air bubble material and return it to the cryopump regeneration system in preparation for the next cryo regeneration process. This includes both sorption pumps.

In the present invention, "regeneration" refers to means such as raising the temperature of the cryo surface when the condensed and adsorbed gas to be pumped is saturated and the pumping capacity is lost. This refers to releasing and removing the cryo from the adsorption surface, restoring the original cryo surface and regenerating the pumping action.

Therefore, the present invention has developed a vacuum pump system having the ability to compress and discharge gas to atmospheric pressure, consisting of a regenerated 2-ion pump, a pulp pump, a pan full pump, and a rotary pump, an oil-free high vacuum mechanical pump, and a pipe having an isolation pulp. Connected by road.

However, a plurality of hydrogen absorbers are arranged in parallel in the pipe line upstream of the vacuum pump system.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred example of the apparatus of the present invention will be described in further detail with reference to the accompanying drawings.

In the figure, X is a cryopump to be regenerated, and this cryopump It is a communication.

The attached drawing shows two hydrogen bombs d1, s, and d2.
are shown, and these hydrogen ab/-had 1, d
Each of z is equipped with isolation pulp elte2.

The pipe Y connecting each of the above-mentioned members communicates with a relatively small capacity vacuum pump system Z for discharging gases other than hydrogen-based gases, and the vacuum pump system 2 mainly uses isolation pulp e.

It consists of an oil pan full f1, a rotary pump g, and a nitrogen barge pulp h. In the figure, k indicates a Pirani vacuum gauge and t indicates a partial pressure gauge.

The operating mode of an embodiment of the present invention having the above-mentioned configuration will be explained.

When cryopump Evacuate te2 and all lines to below 10 Torr.

At this time, the nitrogen purge pulp h is activated at the same time to flow a small amount of clean gas, for example nitrogen or argon, towards the rotary pump g to prevent backflow of oil vapor from the rotary pump g.

Next, nitrogen barge pulp h1 isolation valve e
Close the hydrogen chamber d1. d2 is heated to the optimum temperature T.

The optimum temperature T for the hydrogen absorber d1, d2 depends on the material, metal and compound of the hydrogen absorber used, and has a certain upper and lower limit T2. Since there is TI, TI (T (T
It is preferable to set it to 2.

After raising the temperature of the hydrogen absorber (1111d2), start the clean ruler floor b, and open the isolation valve c2.
, and open isolation valve a.

When the Pirani vacuum gauge k reaches a predetermined pressure P2, the isolation pulp C□ is closed and the isolation valve c2 is opened.

When the Pirani vacuum gauge k reaches a predetermined pressure P3, the pulp C2 is closed and the pulp C2 is interposed for a predetermined time 1o.

After leaving it for a predetermined time, open the pulp C□ and check with the partial pressure gauge t that the pressure of the hydrogen gas is below the fixed value P1 (
The partial pressure of this gas is not necessarily low), then nitrogen purge pulp h1 iso 1/--7 Yongbal 7”e
, and at the same time operate the rotary pump g to exhaust other gases to below 10"
Close 1.

The nitrogen bird pulp h and the isolation valve e are closed, and the insulation is carried out for a predetermined time t1.

After leaving it for a predetermined time t1, open the pulp c2 and confirm with the partial pressure gauge t that the pressure of the hydrogen-based gas is below a certain value P2, then open the nitrogen purge pulp h1 ainlation valve e, and at the same time turn on the rotary pump. g to evacuate other gases to below 10-2 Torr and close the pulp C2.

Hydrogen apun bar d1. Stop the operation of d2 and clean ruler floor b, and complete the regeneration operation of the cryopump.

An example of the conditions in the normal regeneration operation described above is as follows: TI As will be described later, the temperature range varies depending on the adsorbent, but in the case of T1 or T2 using Zr strips, T = 3
00°C, T2 - 800°C T = 550°C Pl = 10 Torr P2 2 10 Torr P3 = 5 Torr tQ = 10 minutes By regeneration operations that are repeated 5 minutes after t, the hydrogen absorber d 1
*d The amount of hydrogen gas absorbed in 2 is a predetermined value Qo: For example, 1
If it exceeds 000"", the following two methods can be taken.

(1) Replace the hydrogen adsorbent in the hydrogen absorber with a new one. (2) Attach an auxiliary heater to the hydrogen absorber and raise the internal hydrogen adsorbent to a high temperature, e.g. 850℃, and reverse the hydrogen absorption process. Let the release take place.

In this case, when isolation pal 7''cl or C2 and pulp e are opened and rotary pump g is operated, hydrogen-based gas is discharged to rotary pump g.

Reactivation of the hydrogen adsorbent will take place.

The main metals and their compounds that can be used as hydrogen adsorbents and the optimum temperatures at which they are used are as follows: Metallic Ti or metallic Zr strips, 300°C to 800°C
Sponge Ti-At-Zr alloy 200℃ (T (400℃
Ti-Ni or Zr-Ni sintered body 150℃ (T(
400℃Fe Ni Ti alloy 50℃<T
<150°C The following points should be kept in mind when operating the device of the present invention: (1) When the target gas is radioactive tritium, the saturated hydrogen adsorbent is made from double iron rayon pulp. It is preferable to remove the hydrogen bubbler, dispose of it in another place to avoid danger, and replace it each time.

(2) Use non-flammable oil for the rotary pump.

(3) Use clean gas that does not contain oxygen.

The device of the present invention has the above-mentioned configuration, and its features are as follows: (1) By using a double isolation valve, radioactive gases such as tritium that cannot be released into the atmosphere can be removed. It can be removed and disposed of separately to avoid danger.

(2) Conventional methods require expensive molecular pumps, Roots pumps, etc. to exhaust hydrogen up to 10 Torr.
It is necessary to provide more than one stage, which makes the amount of equipment extremely expensive.

However, according to the configuration of the present invention, for example, the component ratio of hydrogen-based gas and other gases in plasma experiments is 10:1 or more, so the initial equipment cost of the so-called dynamic exhaust system is about the same as that of the conventional system, making it economical. The effect is extremely large.

[Brief explanation of drawings]

The attached drawing is a flow sheet showing an example of the apparatus of the present invention. Turbo compressor (turbo pump), C1 and C2 are double isolation valves, d
□, d2 is a hydrogen pump, e is an isolation pulp, f is an oil pan full, g is a rotary pump, h is a nitrogen purge valve, k is a Pirani vacuum gauge, and t is a partial pressure gauge.

Claims (1)

[Claims] 1. Between the cryopump and the exhaust system, which has the ability to compress and discharge gas to atmospheric pressure, consisting of pulp, panflu, and rotary pump, oil is sequentially applied from the cryopump side to capture hydrogen-based gas. 1. A regeneration device for a 2-ion pump, characterized in that a mechanical pump for free high vacuum and a plurality of hydrogen absorbers having isolation pulp are arranged in parallel. 2. The cryopump regeneration device according to claim 1, wherein the pulp located between the plurality of hydrogen atmospheres and the pipe line is double isolation pulp. 3. The No. 2 ion pump regeneration device according to claim 1, wherein the oil-free high vacuum mechanical pump is a clean rune blower or a turbo compressor.