JPH04121467A - Cryopump - Google Patents

Abstract

PURPOSE:To obtain a compact cryopump capable of regeneration within a short time by providing a gas-liquid separator, a very low temperature coolant forced circulating means, the heating means of the very low temperature coolant, and a cryopanel. CONSTITUTION:At the time of steady exhaust operation, a very low temperature liquefied gas subjected to gas-liquid separation by a gas-liquid separator 11 is passed through an inlet valve 12a and forcedly circulated by a first cryogenic pump 14a. The very low temperature coolant leaving the cryogenic pump 14a cools a cryopanel 16, and is partly liquefied and returned to the gas-liquid separator 11. The very low temperature gas separated there is passed through a very low temperature coolant transfer pipe 30b and returned to a cryogenic refrigerator not shown. At the time of regeneration, a very low temperature coolant feed valve 17 is closed, and a very low temperature coolant bypass valve 20 is opened to hold low temperature coolant transfer pipes 30a, 30b at a very low temperature. The cryogenic pump 14a is stopped, a second cryogenic pump 14b is started, a regenerative bypass valve 21 is opened, and a heater 15 is laid in operating state to conduct evaporation and recovery of the very low temperature liquefied gas in the cryopanel 16 and the heating of cryopanel 16.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a cryopump, which is one type of vacuum evacuation device.

[Conventional technology 1 Conventional equipment includes, for example, cryogenic engineering Vol. 1.21 No.
2 (1986), there is a gas-liquid separation of cryogenic refrigerant (liquefied helium, abbreviated as LHe) in the upper part of the cryopanel, and during steady evacuation, LHe circulates naturally to cool the cryopanel. I was supposed to.

Note that a bypass line is provided so that the cryopanel can be directly cooled without using a gas-liquid separator during pre-cooling from room temperature.

The main gas exhausted in this case is hydrogen.

[Problems to be Solved by the Invention] The above-mentioned conventional technology does not take into account the regeneration time of the cryopanel, and has the problem that regeneration takes a long time.

In other words, in principle, a cryopump adsorbs and solidifies gas on a metal surface cooled to an extremely low temperature, so after exhausting a predetermined amount of gas, it is necessary to desorb the adsorbed and solidified gas through regeneration. There is. Desorption is performed by heating the cryopanel to a temperature above the liquefaction temperature of the gas at atmospheric pressure. For example, in the case of hydrogen, the liquefaction temperature under atmospheric pressure is about 20°C, and the cryopanel temperature is about 30°C.
It is sufficient to raise the temperature to ~40K.

In the above conventional technology, LHe held in the system during regeneration is
The only way to evaporate and raise the temperature to a predetermined temperature is through heat intrusion, such as conduction, received by the cryopanel within a vacuum-insulated container, which requires a long regeneration time.

An object of the present invention is to provide a lyopump that can be regenerated in a short period of time, and a further object of the present invention is to provide a lyopump that can be regenerated in a short period of time.

Means for Solving the Problem] In order to achieve the above object, a gas-liquid separator, an extremely low temperature refrigerant forced circulation means, an extremely low temperature refrigerant heating means, and a cryopanel are provided.

[Function] During steady pumping, the cryogenic refrigerant forcibly circulated by the cryogenic refrigerant forced circulation means cools the cryopanel in a gas-liquid mixed phase state, and then is separated into gas and liquid by the gas-liquid separator.

During regeneration, the cryogenic refrigerant forcibly circulated by the cryogenic refrigerant forced circulation means is heated by the heating means and introduced into the cryopanel, and the cryogenic liquefied refrigerant held in the cryopanel is evaporated, and the cryogenic refrigerant is The panel is heated to a predetermined temperature and the exhaust gas trapped in the cryopanel is desorbed. After desorption, the exhaust gas is exhausted by a roughing system, and the cryopanel is cooled to a predetermined temperature by forcedly circulating the cryogenic liquefied gas again.

As described above, since the minimum necessary range is heated and cooled during regeneration while forcing the cryogenic refrigerant to circulate, a cryopump with short regeneration time and high operating rate can be achieved. Furthermore, because of the forced circulation type, the number of cryogenic refrigerant passages within the cryopanel can be reduced and the cryopanel can be made more compact.

[Example] An example of the present invention will be described below with reference to FIG. 1st
In the figure, 11 is a gas-liquid separator, 14a and 14b are cryogenic pumps that are cryogenic refrigerant forced circulation means, 12a and 12b are cryogenic pump artificial valves, 13 is a cryogenic pump bypass valve, and 15 is cryogenic refrigerant heating. Heater as a means, 16
1 is a cryopanel, 17 is a cryogenic refrigerant supply valve, 18 is a cryogenic refrigerant return valve, 19 is a regeneration return valve, 20 is a cryogenic refrigerant bypass valve, 21 is a regeneration bypass valve, 30a, 30b, 3
0c is a vacuum-insulated cryogenic refrigerant transfer pipe, and 10 is a vacuum-insulated container containing equipment.

Next, the operation of this embodiment configured as described above will be explained. First, the steady exhaust operation will be explained.

The cryogenic liquefied gas separated into gas and liquid by the gas-liquid separator 11 passes through the first cryogenic pump artificial valve 12a and is forcedly circulated by the first cryogenic pump 14a. The cryogenic refrigerant that has exited the first cryogenic pump 14 a passes through the heater 15 in the OFF state, is introduced into the cryopanel 16 , cools the cryopanel 16 , is partially gasified, and returns to the gas-liquid separator 11 . The cryogenic liquefied gas required by the cryopump system is supplied through the first cryogenic refrigerant transfer pipe 30a, and is supplied while maintaining the liquid level in the gas-liquid separator 11 with the cryogenic refrigerant supply valve 17. The cryogenic gas separated by the gas-liquid separator 11 passes through the cryogenic refrigerant return valve 18 and the second cryogenic refrigerant transfer pipe 30b, and returns to the cryogenic freezing rock (not shown). The cryogenic pump bypass valve 13 is provisionally provided so that a minimum amount of cryogenic liquefied gas is naturally circulated even when the first cryogenic pump 14a is stopped. The other valves and the second cryogenic pump 14b are closed and inoperative.

Next (Second) The operation during regeneration will be explained. The cryogenic refrigerant supply valve 17 is closed, and the first and second cryogenic refrigerant transfer pipes 30
The cryogenic refrigerant necessary to maintain a and 30b at a cryogenic temperature is allowed to flow by opening the cryogenic refrigerant bypass valve. The first cryogenic pump 14a is stopped and the first cryogenic pump inlet valve 12
4b is started, and the regeneration bypass valve 21 is opened. The heater 15 is activated, and the evaporation and recovery of the cryogenic liquefied gas in the cryopanel 16 and the heating of the cryopanel 16 are started. While the temperature of the return gas from the gas-liquid separator 11 is sufficiently low, the cryogenic refrigerant return valve 18
However, when the gas temperature rises, the return valve 19
The refrigerant is switched to the third cryogenic refrigerant transfer pipe 30c and returns to the cryogenic refrigerator. Once the cryopanel 16 is heated to a predetermined temperature, the heater 15 maintains the temperature at the predetermined temperature.

After the exhaust gas desorbed from the cryopanel 16 is exhausted by a rough evacuation system (not shown), the heater 15 is stopped, the second cryogenic pump 14b is stopped, and the regeneration bypass valve 21 is closed. The first cryogenic pump artificial valve 12a is opened and the first cryogenic pump 14a is activated. At the same time, the cryogenic refrigerant bypass valve 20 is closed, and the liquid level control of the gas-liquid separator 11 is started by the cryogenic refrigerant supply valve 17. When the temperature of the return gas from the gas-liquid separator 11 drops sufficiently, the return valve 19 is switched to the cryogenic refrigerant return valve 18 during regeneration. By the above,
Regeneration is complete when the cryopanel 16 is recooled to a predetermined temperature. In addition, the second cryogenic pump artificial valve 12b
is preliminarily installed so that it can also be used for forced circulation of cryogenic liquefied gas.

According to this embodiment, there is an effect that a cryopump with a short regeneration time and a high operating rate can be achieved. Furthermore, this embodiment has the effect of making the cryopump smaller. Although the cryopump is housed in a single insulated vacuum container, if there are restrictions on placement, the insulated vacuum container can be divided into multiple parts. , and can be connected by a cryogenic refrigerant transfer pipe.

In addition, by installing a control device and automating playback operations, etc.
The reliability of the device can be improved, as well as the operability of the device.

[Effects of the Invention] According to the present invention, a cryogenic refrigerant is forced to circulate and only the minimum necessary range can be heated and cooled during regeneration, so that the regeneration time is short and the device has a high operating rate. Further, there is an effect that the cryopump can be made smaller.

[Brief explanation of drawings]

FIG. 1 is a system diagram of a cryopump according to an embodiment of the present invention.

Claims (1)

[Scope of Claims] 1. A cryopump that adsorbs and exhausts gas using a cryopanel cooled with a cryogenic refrigerant, which comprises a gas-liquid separator for the cryogenic refrigerant, a cryogenic refrigerant forced circulation means, and a cryogenic refrigerant heating means. A cryopump comprising: and a cryopanel. 2. The cryopump according to claim 1, wherein a heater is used as heating means for the cryogenic refrigerant. 3. The cryopump according to claim 1, wherein a cryogenic pump is used as the forced circulation means for the cryogenic refrigerant. 4. The cryopump according to claim 1, further comprising a line that bypasses the cryogenic refrigerant forced circulation means. 5. The cryopump according to claim 1, wherein the forced circulation means for cryogenic refrigerant includes at least two types, one for cryogenic liquefied refrigerant and one for cryogenic gas refrigerant. 6. The cryopump according to claim 1, wherein the insulated vacuum container housing the equipment constituting the cryopump is divided into a plurality of parts, and the parts are connected by a vacuum-insulated cryogenic refrigerant transfer pipe. 7. The cryopump according to claim 1, further comprising a bypass line from the cryopanel outlet to the cryogenic refrigerant forced circulation means input. 8. The cryopump according to claim 1, which is provided with a control device to automate regeneration operations and the like.