JPH01260264A - Very-low-temperature refrigeration device - Google Patents

Abstract

PURPOSE:To make a rotary machine excellent in ability to sustain continuous operation over long periods of time by drawing from a very-low-temperature refrigerating device cryogenic gas at a temperature level at which oils, impurities, and the like can be removed completely through solidification and using the cryogenic gas as static pressure-bearing gas in the rotary machine. CONSTITUTION:High pressure helium, after removal of oils therefrom by an oil separator 3, is conveyed from a compressor unit 1 to a refrigerator 5 wherein it is cooled from an ordinary temperature to a point for its liquefaction, causing all the impurities in the liquefied gas to solidify and attach to heat exchangers 6a, 6b, piping, and the like; the oil that may possibly mix into it at the compressor unit 1 has a high solidifying point and gets caught through solidification in the refrigerator 5 at early stages. The cryogenic gas which has been discharged from an internal adsorber 7 after complete removal of oils and impurities is made to branch off at the outlet into a bearing gas feed line 35 and is conveyed through a bearing gas feed valve 33 to a thrust bearing 25 which is a static gas-pressure bearing. Without admitting oils and impurities to the bearing the device enables a rotary machine to sustain continuous operation over long periods 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 those having rotating equipment of a hydrostatic gas bearing type.

[Conventional technology]

Currently, cryogenic refrigeration equipment, such as helium refrigeration equipment,
Oil injection type screw compressors are used in most of the pressure ms. This is because the oil injection screw compressor is a device with good long-term continuous operation, is highly reliable, and has excellent operability, and is also due to advances in oil separation technology. Currently, in the Oil II device,
The oil content in the discharged gas can be removed to 0.1 pp (Vol, ) or less.

On the other hand, most expansion turbines, which are the heart of cryogenic refrigeration equipment, employ static pressure gas bearings. Hydrostatic gas bearings inject high-pressure gas through pores to levitate a rotating body, but the floating height is from several microns to several tens of microns, requiring ultra-precision machining. If it is not possible to prevent not only solid matter from getting into the tank but also impurities such as oil, normal operation will not be possible.

Conventional equipment directly introduces room temperature gas from the compressor unit as hydrostatic bearing gas.

Note that related devices of this type include, for example,
"Turbo Machinery No. 11 Building No. 7", July 1983, No. 3
An example is "Expansion turbine for He liquefaction refrigerator" described in page 7 to page 42.

[Problems to be solved by the invention] The above-mentioned prior art does not deal with the fact that trace amounts of oil and impurities are mixed in the discharge gas of the compressor unit even during normal operation, and it does not deal with the fact that small amounts of oil and impurities are mixed in the discharge gas of the compressor unit, and it is difficult to solve the problem of long-term continuous operation. When giving,
There is a problem in that there is a high possibility that oil, impurities, etc. will enter the bearing portion and deteriorate the bearing performance of the expansion turbine. In addition, due to incorrect operation or failure to regenerate the oil separator, large needles of oil may get mixed in. In this case, there is a high possibility of damage to the expansion turbine. There is a problem in that a large amount of time and cost are required for inspection, cleaning, assembly, etc.

An object of the present invention is to provide a cryogenic refrigeration system with excellent long-term continuous operability.

[Means to solve the problem]

The above object is achieved by extracting a low-temperature gas from a cryogenic refrigeration device at a temperature level at which oil, impurities, etc. are completely solidified and removed, and using it as a hydrostatic bearing gas for rotating equipment.

[For production]

Cryogenic freezing! In the refrigerator, refrigerant gas at room temperature and high pressure is introduced from the compressor unit into the refrigerator and cooled from room temperature to liquefaction humidity within the refrigerator. (In addition, oil that may be mixed in from the compressor unit has a high solidification point and solidifies and adheres to the inside of the refrigerator at an early stage.) Oil and impurities are completely removed. The removed low-temperature refrigerant gas is branched out from the refrigerator and used as static pressure bearing gas for rotating equipment.This eliminates the possibility of oil or impurities getting into the bearings of rotating equipment, allowing long-term continuous operation. Driving becomes possible.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 shows, for example, a helium refrigeration device as a cryogenic refrigeration gti, and an expansion turbine as a rotating device. In FIG. 1, l is a compressor unit.

2 is pressure 11@W, 3 is oil content 11! 4 is a helium refrigerator artificial valve, 5 is a helium refrigerator 11R, 6a to 6d are heat exchangers, 7 is an internal adsorber, 8 is an expansion turbine artificial valve, 9 is a Joule-Thomson valve (hereinafter abbreviated as JT valve) ), 1
0 is a liquid nitrogen supply pipe, 11a and llb are low temperature transfer pipes, 戎 is a cooling equipment, and l is an expansion turbine.

4 is a brake valve, n is a cooler, container is a journal gas bearing, 2
4 is a rotor, 25 is a static pressure gas bearing type thrust bearing (hereinafter referred to as a thrust bearing), 26 is a braking fan, 30 is a bearing gas warmer, 31 is a check valve, and the proverb is a bearing gas bubble tank (hereinafter referred to as a thrust bearing). (abbreviated as Babfur tank), 33 is a bearing gas supply valve, tool is a bearing gas extraction valve, A is a bearing gas supply line, and winnow is a bearing gas return 1J line.

Next, the operation of the helium refrigeration system configured as described above will be explained.

The high-pressure helium compressed by the compressor 2 is removed from the oil to below 0.1 ppm (Vol, ) by the oil separator [3].

It exits the compressor unit 1, passes through the helium refrigerator artificial valve 4, and is introduced into the helium refrigerator 81!5. The room temperature high pressure helium introduced into the helium refrigerator 5 is transferred to the 10th heat exchanger 6a.
Then, the liquid nitrogen supplied from the liquid nitrogen supply pipe 10 and the low-pressure return helium exchange heat and are cooled to about 80K.
All trace amounts of oil that could not be removed by the oil separator WL3 are assimilated in the first heat exchanger 6a and removed from the helium gas.

The high-pressure helium that exits the heat exchanger 6a of 151 passes through an internal adsorber 7 that adsorbs and removes impurity gases such as nitrogen and oxygen having assimilation points below 80, and is further cooled in the second heat exchanger 6b. After that, it branches into an expansion turbine line and a liquefaction line, and the high-pressure helium branched into the liquefaction line flows into the third and fourth lines.
heat exchanger 6c.

6d, adiabatic free expansion occurs in the JT valve 9, a portion of which becomes liquid helium, which is sent to the cooled facility through the low temperature transfer pipe 11a, where it absorbs the heat load, and then transferred to the low temperature transfer pipe 11b. and returns to helium refrigerator 5 again.
The temperature is recovered by the first heat exchangers 6d to 6a and then returned to the compressor unit 1.

On the other hand, the high-pressure helium branched into the expansion turbine line is introduced into the expansion turbine I through the expansion turbine artificial valve 8, where it expands adiabatically and gives rotational power to the rotor. . The rotational power applied to the rotor is transmitted to the braking fan, where it is consumed by compressing and circulating braking helium gas. Braking helium gas is supplied to cooler 22. It circulates through the brake valve 4. The rotating part of the expansion turbine is suspended and supported by a journal gas bearing n using a gas bearing and a thrust bearing 5 in order to rotate at a high speed of several hundred thousand rotations per minute.

In this case, the bearing gas supplied to the thrust bearing 6, which is a static pressure gas bearing, is not only oil mixed in the outlet gas of the compressor unit 1, but also nitrogen.

The low-temperature gas on the outlet side of the internal adsorber 7, from which impurity gases such as oxygen have also been removed, is branched and led out to the bearing gas supply line.
Check valve 31. Buffer tank β.

The gas is supplied to the thrust bearing 5 via the bearing gas supply valve.

Reverse valve 31. The Paffer tank is provided so that even if the helium refrigerator artificial valve 4 suddenly closes during an emergency stop, the necessary bearing gas can be supplied until the expansion turbine safely stops. A similar function can be obtained by using a thick pipe instead of the Babfur tank n. Note that after the bearing gas leaves the expansion turbine I, it returns to the pressure l@machine unit 1 through a bearing gas return line A having a bearing gas extraction valve A.

According to this embodiment, even if a large amount of oil gets mixed in due to an abnormality such as incorrect operation, as well as a small amount of oil and impurities during normal operation, long-term continuous operation is possible because oil and impurities do not enter the expansion turbine. In addition, even if a large amount of oil is entrained from the compressor unit, only the area from the compressor to the first heat exchanger needs to be cleaned, which has the effect of greatly reducing the recovery period and cost. .

Note that in this example, an expansion turbine was explained, but
Low humidity compression 8! Needless to say, the present invention can also be applied to static pressure gas bearing rotating equipment such as low-temperature exhaust pumps.

For example, FIG. 2 shows a second embodiment of the invention.

In this case, FIG. 2 shows a cooling device that circulates supercritical pressure helium gas to cool the object to be cooled.

In this figure, the same reference numerals as in FIG. 1 indicate the same members, and their explanation will be omitted. This diagram differs from Figure 1 in that low-temperature transfer pipes 11a and llb from the helium refrigerator 5 are connected to a dewar 13 that stores liquid helium, and separate low-temperature transport pipes 16a and 16b are connected from the dewar 13. Cooled equipment 4a1
4, and a heat exchanger, in this case, heat exchanger tubes 15 and 17, is provided in the dewar 15 and the cooled equipment 14,
The heat transfer tubes 15 and 17 and the low temperature transfer pipes 16a and 16b are connected to form a circulation circuit, and in this case, the low temperature transfer amount @
16a, and supports the rotating part to which the fan 41 of the cryogenic pump 40 is attached. In this case, the internal adsorber 7 of the helium refrigerator 5 is attached to the journal bearing 42 and the thrust bearing 4 of the hydrostatic gas bearing type.
The point is that the branched gas is introduced from the downstream side. In addition, 18 is a bubble tank, 19 is a pressure control valve, and the shrine is a motor that rotates the fan 41.

The operation of the cooling device configured in this way will be explained.

In this case, the helium gas pressure in the circulation circuit of the low-temperature transfer pipes 16a, 16b is kept constant within 5 to 10 g atm, and the heat exchanger tube 15 cools the helium to near the liquid helium temperature. Supercritical pressure helium gas under such pressure and am state is prepared by rotating the fan 41 using a motor or the like.

As a result, the object to be cooled is cooled by the heat exchanger tube 17, and the heated helium gas returns to the heat exchanger tube 15 and is recooled.

In addition, the low temperature gas branched from the downstream side of the internal adsorber 7 is heated to near room temperature in the bearing gas supply line, ie, the bearing gas warmer 7, and is heated to near room temperature with a check valve 31° in the Paffer tank!
The gas is supplied to the journal bearing 42 and thrust bearing 0 of the low temperature pump via the bearing gas supply valve 0. The used bearing gas is returned to the compressor unit 1 via the bearing gas return line and the bearing extraction valve.

According to the above-mentioned embodiment 1, as in the embodiment described in llff, since low humidity gas from which oil and impurities have been completely removed is used as the bearing gas, there is no possibility of oil or impurities getting mixed into the bearing part. This has the effect of enabling long-term continuous operation.

Further, there is an effect that oil and impurities can be prevented from entering the circulation circuit forming a closed loop from the low-humidity pump section.

Furthermore, since the circulation circuit is a single-phase flow of helium gas, the circulation circuit can be constructed easily.

〔Effect of the invention〕

According to the present invention, since a complete return gas can be used in a hydrostatic gas bearing type rotary device, there is an effect that long-term continuous operation is possible.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing a cryogenic refrigeration system h''7 which is one embodiment of the present invention, and Fig. 2 is a block diagram showing a cryogenic refrigeration system which is another embodiment of the present invention.1. ... Compressor unit, 5 ... Helium refrigerator, 13 ... Dewar-114 ...
・Object to be cooled, 15, 17... Heat exchanger tube, 16a,
16b...Low temperature transfer piping, expansion turbine, 25...Thrust bearing, I...
... Bearing gas adder, 31... Check valve, proverb...
...Bearing gas bubble tank, A...Bearing gas supply valve, A...Bearing gas supply line, 40
...Low humidity pump, 42...Journal bearing, Q...Thrust bearing Fig. 41 Fig. A2

Claims (1)

[Claims] 1. A cryogenic refrigeration system having a rotating device using a hydrostatic gas bearing, characterized in that a refrigerant gas cooled within the cryogenic refrigeration system is used as a bearing gas for the bearing. Cryogenic freezing equipment. 2. The cryogenic refrigeration apparatus according to claim 1, wherein the cooled refrigerant gas is used for the bearing gas after recovering its humidity. 3. The cryogenic refrigeration system according to claim 1, wherein bearing gas can be stored for the time required for an emergency stop of the rotating equipment. 4. A hydrostatic gas bearing type rotating device characterized in that a refrigerant gas cooled in a cryogenic refrigerator is used as the bearing gas of a rotating device using a hydrostatic gas bearing. 5. A heat exchanger that exchanges heat with the liquefied gas in the storage container, and a heat exchanger that exchanges heat with the liquefied gas in the storage container, and a A circulation circuit formed through a heat exchanger that exchanges heat with the object to be cooled is provided, and refrigerant gas cooled by the cryogenic refrigeration device is supplied to the bearing gas of the static pressure gas bearing of the circulation pump provided in the circulation circuit. A cooling device characterized in that it is used.