JPH0233877B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a method of supplying cryogen to a cryopump having a gas-liquid separator in the upper part of the cryo-exhaust section. Here, the case of a cryopump will be explained. The same is true for cryostat.

[Background of the invention]

Cryogen is supplied to a conventional cryopump with a gas-liquid separator using piping and valves shown in FIG. That is, when precooling the cryopump from room temperature, the precooling valve 5 is opened and the steady supply valve 6 and the steady circulation valve 7 are closed. A gas-liquid two-phase cryogen such as liquid helium or liquid hydrogen sent from a refrigerator or a refrigerator is sent to a cryogen supply section 3, a pre-cooling valve 5, a supply pipe 4, a cryo exhaust section 1, a gas-liquid separator 2, and an evaporative gas discharge. It passes through section 8 and is either released into the atmosphere or returned to the refrigerator. At this time, after the cryo exhaust section 1, which has a large heat capacity, is cooled to the boiling point of the cryogen, the gas-liquid separator 2
Cryogen liquid accumulates in the Thereafter, the precooling valve 5 is closed, and the steady supply valve 6 and the steady circulation valve 7 are opened.
The gas-liquid two-phase cryogen is supplied through a cryogen supply section 3 and a steady supply valve 6.
The liquid phase component remains in the gas-liquid separator 2, and the gas phase component is discharged to the outside of the cryopump through the evaporative gas discharge section 8. In addition, the gas-liquid separator 2, the steady circulation valve 7, the supply pipe 4, and the cryo exhaust section 1 form a circulation line, and since the cryo exhaust section 1 is subjected to a heat load, the liquid refrigerant in the cryo exhaust section 1 is in a gas phase. This buoyant force creates a circulating drive force that supplies liquid cryogen to the cryo exhaust located within this circulation line.

[Purpose of the invention]

The purpose of the present invention is to enable the conventional supply method, which required three valves, to be performed using two valves.

[Embodiments of the invention]

Embodiments of the present invention are shown in FIGS. 2 and 3.

In the case of FIG. 2, when the cryopump is precooled from room temperature, the precooling valve 5 is opened and the steady supply valve 6 is closed. The gas-liquid two-phase cryogen sent from the refrigerator or JYCU passes through the cryogen supply section 3, pre-cooling valve 5, pre-cooling piping 9, cryo exhaust section 1, gas-liquid separator 2, and evaporative gas discharge section 8 to the cryopump. It is discharged outside. At this time, the cryogen flows from the precooling pipe 9 to the gas-liquid separator 2 even if it passes through the steady circulation pipe 10 in parallel with the cryo exhaust section 1 . Generally, the heat capacity of the cryo exhaust part is larger than that of the steady circulation pipe 10, so it seems that only the steady circulation pipe 10 is precooled and the cryo exhaust part 1 is not efficiently precooled.
However, when the cryogen flowing through the pre-cooling pipe 9 is in two phases: gas and liquid, when the rising pipes that flow horizontally at the bottom of the cryo exhaust section and then go upward become parallel, the buoyant force due to the gas phase in the two-phase gas and liquid causes Most of the flow flows into the rising piping where the flow first encounters it. For this reason, in the embodiment shown in FIG. 2, the cryo exhaust section is connected to the rising pipe that first encounters the precooling pipe 9 after it becomes horizontal, so that the cryo exhaust section 1 is efficiently precooled even if the heat capacity is large, and the cryogen is After being cooled to the boiling point of , the liquid refrigerant accumulates in the gas-liquid separator 2. The cryogen supply method in the steady state after this is the same as in the conventional case. That is, the precooling valve 5 is closed and the constant supply valve 6 is opened. The gas-liquid two-phase cryogen flows through the cryogen supply section 3 and steady supply valve 6 to the gas-liquid separator 2, the liquid phase remains in the gas-liquid separator 2, and the gas phase flows from the evaporated gas discharge section to the cryopump. is discharged outside. In addition, the gas-liquid separator 2, steady circulation piping 10, and cryo exhaust section 1 form a circulation line, and a thermal load is applied to the cryo exhaust section.
A gas phase component is generated in the liquid cryogen, generating a circulation driving force due to buoyancy, and the liquid cryogen is efficiently supplied to the cryo exhaust section 1 in this circulation line.

In the embodiment shown in FIG. 3, there are two or more cryo exhaust units. The opening and closing of the valve during pre-cooling and steady state is the second
This is the same as in the embodiment shown. During pre-cooling, the gas-liquid two-phase cryogen flowing through the pre-cooling pipe 9 flows horizontally, and the rising pipe that encounters it first is connected to the cryo exhaust section 1, and the rising pipe that encounters it the latest serves as the steady circulation pipe 10. The cryo exhaust section 1 having a large heat capacity is efficiently precooled.
What differs from the embodiment shown in FIG. 2 in the flow of the cryogen in a steady state is that the cryogen is supplied to the cryo exhaust section 1 in parallel. At this time, the refrigerant flowing through the steady circulation pipe 10 is only the liquid phase separated from the gas and liquid by the gas-liquid separator 2, and there is no particularly large amount of refrigerant flowing from the horizontal section to the rising pipe where it first meets, and it is almost uniform. is expected to flow.

In the above explanation, the cryogen was explained as having two gas-liquid phases in the cryogen supply section 3, but even if the cryogen is only in the liquid phase, the pressure decreases after passing through the pre-cooling valve 5 or the steady supply valve 6, and the cryogen becomes gas-liquid. The present invention is effective even in the case where they are in phase.

〔Effect of the invention〕

As described above, the conventional method required three valves to supply cryogen to the cryo exhaust section 1 for switching between precooling and steady state, but it can be done with two valves according to the present invention. This makes it possible to reduce the heat load on the cryopump and at the same time facilitate control of the operation of the cryopump.

[Brief explanation of drawings]

Fig. 1 is a system diagram showing a conventional cryopump cryogen supply system, Fig. 2 is a system diagram showing a cryopump cryogen supply system according to an embodiment of the present invention, and Fig. 3 is a system diagram showing a cryopump cryogen supply system having multiple cryopumps. FIG. 3 is a system diagram of a cryogen supply system of a cryopump showing another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Cryo exhaust part, 2... Gas-liquid separator, 3... Cryogen supply part, 4... Supply piping, 5... Precooling valve, 6... Steady supply valve, 7... Steady circulation valve, 8... Evaporative gas discharge part,
9... Pre-cooling piping, 10... Steady circulation piping.

Claims (1)

[Claims] 1. In a cryopump having a gas-liquid separator on the upper part, a pre-cooling pipe having a pre-cooling valve for pre-cooling and supplying a cryogen in a steady state, and a steady circulation pipe connecting the gas-liquid separator and the cryo exhaust part are provided. Also, when the cryogen is supplied from the lower part of the cryo exhaust part through the precooling pipe during precooling of the cryopump, the first rising part from the horizontal pipe is connected to the cryo exhaust part, and no valve is required in the steady circulation pipe. A cryopump cryogen supply system featuring: 2. A cryogen supply system for a cryopump according to claim 1, wherein a cryostat is used in place of the cryopump, and a cryo heat receiving part is used in place of the cryoexhaust part.