JPH01260265A - Very-low-temperature refrigeration device - Google Patents

Abstract

PURPOSE:To enable a cold box, which produces a liquefied gas at a very low temperature level rendering impurities removable by solidification or adsorption, to sustain continuous operation over a long period of time by dividing the ordinary temperature side of the cold box into a plurality of units in a setup to alternate their use. CONSTITUTION:High pressure helium gas at an ordinary temperature is conveyed from a compressor unit 1 to units 10a, 10b of a first cold box, wherein the helium gas drawn into a first heat exchanger 11a is cooled to about 80K by heat exchange with liquid nitrogen or the like supplied through a liquid nitrogen feed pipe 13a; gaseous impurities which remain unsolidified are removed by adsorption at internal adsorbers 12a, 12b so that a high purity gas is obtainable from the outlet of the cold box on the ordinary temperature side. This gas is then fed into a second cold box 20 on the low temperature side. The use of the cold box on the ordinary temperature side, which is divided, is alternated between the units 10a, 10b at suitable intervals of time according to the amount of the impurities solidified or adsorbed in order to make the removal continuous so that the system can sustain continuous operation over a long period of time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a cryogenic refrigeration system, and particularly to a cryogenic refrigeration system suitable for equipment that requires long-term continuous operation.

[Conventional technology]

For example, in a helium refrigeration system.

Currently, an oil injection screw compressor is used for post-compression. This is because the oil injection screw compressor has high reliability as a device such as long-term continuous operation, excellent operability, and advances in oil separation technology.

Currently, the oil content is 1lIl! In the device, the oil content in the discharged gas is
-11) It is assumed that it can be removed to below I)m (Vol). In addition, superconducting magnets are a typical type of equipment to be cooled in helium refrigeration equipment, but superconducting magnets have a complex structure and use a large amount of organic material, making it difficult to replace and remove impurity gas. be. Furthermore, if a freezing temperature below 4.4 is required, it is necessary to create a reduced pressure state that is IJ lower than the atmospheric pressure.In this case, there is a possibility that impure gases such as air may be drawn into the system from the atmosphere. remain.

As mentioned above, cryogenic refrigeration equipment (although the amount is small,
Various impurities are continuously mixed into the refrigerant gas,
Conventional low-temperature refrigeration equipment has only been seen to be equipped with an internal suction device at the liquid nitrogen temperature level (approximately 80K), which is auxiliary cooling IIIλ.

Regarding this kind, Japanese Patent Application Laid-Open No. 57-62
No. 368 etc. are mentioned.

[Problem to be solved by the invention]

The above-mentioned conventional technology eliminates oil from the compressor and oil from the equipment to be cooled.
02 + No consideration was given to the fact that impurities from each building, such as water, air from the decompression line, etc. (each has a different assimilation temperature), may be mixed into the refrigerant gas, even if it is at the base of the refrigerant gas. There was a problem in that it could not be applied to equipment that required continuous operation for a period of time. The above-mentioned various impurities assimilate and grow at each assimilation temperature level within the cryogenic refrigeration equipment, increasing the flow resistance of the high-pressure refrigerant gas, and in extreme cases, the equipment must be stopped.

An object of the present invention is to provide a cryogenic refrigeration system that can be operated continuously for a long period of time.

[Means to solve the problem]

The above object is achieved by dividing the cold box at a temperature level at which impurities can be removed by solidification or adsorption, and by providing a plurality of divided cold boxes on the room temperature side so that they can be used interchangeably.

[For production]

The room-temperature high-pressure gas introduced into the divided cold box on the room-temperature side solidifies each impurity as the temperature drops 21! The impurity gas that did not solidify was adsorbed and removed by the internal suction device, and became high-purity gas at the outlet of the divided cold box on the room temperature side.
I's cold box.

The divided cold box on the room temperature side is used to assimilate impurities,
Or switch to another cold box on the room temperature side at a reasonable time by adsorption.

〔Example〕

An embodiment of the present invention will be described below using the m1 diagram.

In Figure 1, 1 is a compressor unit, 2 is a compressor, and 3 is an oil separator! , 10a and 10b are the divided room temperature side first cold boxes, 11a and 11b
is the first heat exchanger, 12 a and 12 b are internal adsorbers, 13 a and 13 b are liquid nitrogen supply pipes, 14 a
and 14b are high pressure gas valves, 15a and ts
b is a high pressure gas outlet valve; 16. and 16 b are low pressure gas outlet valves, 17 a and 17 b are low pressure gas population valves, 1
8a and 18b are liquid nitrogen supply valves, the cold box of man 2 is the divided low temperature side, 21 is the second heat exchanger, 22 is the third heat exchanger, 23 is the fourth heat exchanger ,
Sae is the expansion valve, 5 is the expander, Han is the Joule-Thomson valve (hereinafter referred to as JT valve), and father is the refrigerated equipment.

Next, the operation of the cryogenic refrigeration apparatus configured as above will be explained. In this case, the first coal topo box has two systems 10a and 10b, and system a is in refining operation.
Assume that line b is being regenerated. The normal humidity high pressure helium discharged from the compressor unit l is sent to the cold box 10a of ff1l, and is transferred to the liquid nitrogen supply pipe 13 in the first heat exchanger 11a.
Liquid nitrogen supplied from a.

Then, it exchanges heat with low pressure gas and is cooled to about 80K. During this time, the oil content in the high pressure gas, 002. Impurities such as water having an assimilation temperature of about 80 or higher are assimilated and removed in the first heat exchanger 11a. All impurities such as N2+02 in the high pressure gas exiting the first heat exchanger 11a are adsorbed and removed by an internal adsorber 12a filled with activated carbon, etc., and are transferred to the second cold box as high-purity high pressure gas. will be introduced in The high-purity high-pressure gas introduced into the second cold box is cooled by the second heat exchanger 4, and then branched into the expander line and the liquefaction line, and the gas in the expander line is transferred to the expander valve. The gas passes through the gas, expands adiabatically at an expansion rate of 8!5, and after the temperature decreases and generates cold, it merges with the low pressure gas. The gas branched into the liquefaction line is further cooled down in the third and fourth heat exchangers n, 23. , JT Benkan undergoes adiabatic free expansion and partially liquefies, absorbing the cooling load between the cooled equipment. Cooled equipment (
The low-pressure gas absorbed the cooling load and gasified by the second
Return to cold box I, and heat exchanger 2 from 4th to @2
After being cold-recovered in steps 3 to 21, it is further cold-recovered in the first heat exchanger 11a in the first cold box 10a and returned to the compressor unit 1.

On the other hand, the b system that is being regenerated first starts with the high pressure gas valve 14b.
, the high-pressure gas outlet valve 15b, the low-pressure gas population valve 17b, the low-pressure gas outlet valve 16b, and the liquid nitrogen supply valve 18b are closed, and the system is depressurized using a discharge line (not shown).

Thereafter, a heating line (not shown) is used to heat the inside of the system to around room temperature, and further, impurity gas is removed from the system by evacuation and displacement. After the impure gas has been removed from the system, liquid nitrogen is supplied.

Cool down to a low temperature that allows refining operations.

According to the first embodiment, impurities mixed into the refrigerant gas from the compressor, equipment to be cooled, etc. can be continuously removed within the minimum necessary temperature range by switching the first cold box. Long-term continuous operation can be achieved at low cost.

In addition, in the example, the first cold box is formed with an independent vacuum cold storage tank to isolate heat from each cold box, but it is formed integrally with the vacuum cold storage tank of the second cold box. However, each part may be separated by a shield tank.

〔Effect of the invention〕

According to the present invention, since various impurity gases from the compressor etc. can be continuously removed by switching the first cold box, long-term continuous operation is possible.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a cryogenic refrigeration system as an embodiment of the present invention.

Claims (1)

[Claims] 1. In a cryogenic refrigeration system consisting of a compressor unit and a cold box that introduces room temperature high pressure gas, which is the discharge gas of the compressor unit, to produce cryogenic liquefied gas, A cryogenic refrigeration system characterized in that a cold box is divided at a certain temperature level between the cryogenic liquefied gas temperature and a plurality of the divided cold boxes on the room temperature side are provided in parallel and can be switched. 2. The cryogenic freezing apparatus according to claim 1, wherein the cold box is divided by auxiliary cold source temperature level. 3. The cryogenic freezing apparatus according to claim 1, wherein an internal adsorption device is provided in the divided cold box on the room temperature side. 4. The divided cold box on the room temperature side is switched when the pressure difference between the inlet pressure and the outlet pressure of the high-pressure refrigerant gas in the divided cold box on the room temperature side becomes equal to or higher than a set value. cryogenic freezing equipment.