JPH03217765A - Cryogenic refrigerator using expansion turbine - Google Patents

Abstract

PURPOSE:To prevent an excess load variation of a turbine even at the time of an erroneous manipulation, or an erroneous operation by attaching slow opening/closing means to an expansion turbine inlet valve or an expansion turbine outlet valve or attaching it to both. CONSTITUTION:After high pressure helium introduced to a cold box 10 via a high pressure line 1 is cooled by a first heat exchanger 11a, it is partly introduced to a first expansion turbine 13a through an expansion turbine inlet valve 12a with a first quick opening preventing mechanism, adiabatically expanded to generate cold, cooled by a third heat exchanger 11c, adiabatically expanded to a low pressure by a second expansion turbine 13b, and combined with a low pressure line 2. After the residual helium is cooled by second-fifth heat exchangers 11b-11e, it is adiabatically expanded by a third expansion turbine 13c through an expansion turbine inlet valve 12b with a second quick opening preventing mechanism to generate cold, then cooled by a sixth heat exchanger 11f, expanded to a low pressure by an expansion turbine outlet valve 14 with a quick opening and quick closing preventing mechanism to absorb heat load of a cold load 20, and returned to a compressor. According to this, an excess load variation to the expansion turbine is prevented even at the time of an erroneous manipulation or an erroneous operation.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a cryogenic refrigeration system having an expansion turbine;
In particular, the present invention relates to a cryogenic refrigeration system suitable for protecting an expansion turbine from sudden pressure fluctuations.

[Conventional technology]

BACKGROUND ART In a low-temperature refrigeration system, such as a helium refrigeration system, a gas bearing type expansion turbine is used as an expander that generates cold. This expansion turbine rotates at a high speed of tens of thousands to hundreds of thousands of rpm to ensure efficiency. Because it is a gas bearing type, the load capacity of the bearing is not large, and if there is a sudden change in the expansion turbine inlet pressure and outlet pressure, an imbalance may occur and the bearing may burn out due to contact or damage due to overspeed. Occurs.

Note that related devices of this type include, for example,
Nihon Kogyo Shuppan “Turbo Machinery No. 11 Kei No. 7 (1983)
．． 7) There is an "expansion turbine for He liquefaction refrigerators."

[Problem to be solved by the invention]

The above-mentioned conventional technology lacks consideration to prevent excessive load fluctuations from being applied to the expansion turbine, and has the problem of not being able to protect the expansion turbine from abnormalities such as erroneous operation, malfunction, and power outage.

An object of the present invention is to provide a cryogenic refrigeration system having a highly reliable expansion turbine.

[Means to solve the problem]

In order to achieve the above object, the expansion turbine inlet valve is equipped with a graceful opening mechanism (for example, a speed controller), or the expansion turbine outlet valve is equipped with a graceful opening and closing mechanism (for example, a speed controller). or both together.

Further, in order to achieve the above object, a means (for example, a speed controller) for gently opening the cold box inlet valve is attached.

[For production]

The expansion turbine inlet valve with a sudden opening prevention means opens only at a limited and constant speed even if it receives a sudden opening signal due to erroneous operation or malfunction. The expansion turbine outlet valve with rapid opening/closing prevention means similarly opens and closes only at a limited and constant speed. This can prevent excessive pressure (load) fluctuations from being applied to the expansion turbine.

In addition, by attaching a sudden opening prevention means to the cold box inlet valve, the cold box inlet valve will not open suddenly, the flow rate to the cold box will gradually increase, and the pressure in the high pressure line will be reduced to the helium compressor discharge side. The pressure control device installed in the chamber ensures stable pressure. Therefore, the turbine bearing gas supply pressure supplied from the high pressure line is also stabilized, so that damage to the turbine bearing can be prevented.

〔Example〕

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

In FIG. 1, l is a high pressure line introduced from a compressor (not shown), 2 is a low pressure line returning to the compressor, 10 is a cold box, lla to llf are first to sixth heat exchangers, 12a, 12b is the first, i! 2 is an expansion turbine inlet valve with a sudden opening prevention mechanism, 13a to 13c are first to third expansion turbines, 14 is an expansion turbine outlet valve with a sudden opening and closing prevention mechanism, and I is a cooling load.

Next, the operation of the embodiment of the present invention configured as described above will be explained. Cold box 10 with high pressure line l
After being cooled in the first heat exchanger US, some of the high-pressure helium introduced into the! ! It passes through the expansion turbine inlet valve 12a with a sudden opening prevention mechanism of l1, is introduced into the first expansion turbine 13a, and is adiabatically expanded to generate cooling.
after being cooled by the heat exchanger UC of the second expansion turbine 1
At step 3b, it expands adiabatically to a low pressure and joins the low pressure line 2. The remaining helium cooled by the first heat exchanger 11 a is transferred to the second to fifth heat exchangers 1 l b = 11 @
After being cooled, it passes through the second expansion turbine inlet valve 12b with a rapid opening prevention mechanism and is adiabatic expanded to about 4 itm in this case in the third expansion turbine 13c to generate cold.
! ! The helium is cooled by the heat exchanger 11f of No. 6, and is finally Joule-Thomson expanded to a low pressure at the expansion turbine outlet valve 14 with a rapid opening/quick closing prevention mechanism to partially generate liquefied helium, thereby reducing the heat load of cooling load No. 4. Absorb. The cryogenic helium returned from the application of the cooling load is cooled and recovered in the sixth to first heat exchangers 11f to lla, and then returns to the compressor through the low pressure line.

According to this embodiment, even in the event of an erroneous operation or malfunction, it is possible to prevent excessive load fluctuations from being applied to the expansion turbine, thereby improving reliability.

In this embodiment, a mechanism for preventing sudden opening or closing is provided at the inlet and outlet of the expansion turbine, but any one of these mechanisms is also effective.

Next, a second embodiment of the present invention will be described with reference to FIG.

The helium gas compressed by the compressor 3 is transferred to the high pressure line l,
It is led to a cold box 10 via a cold box inlet valve 9.

The helium gas led to the cold box 10 undergoes thermal exchange with the return gas of the low pressure line 2 in the heat exchanger 11a, is cooled, and is then adiabatically expanded in the expansion turbines 13a, 13b to become low-temperature gas. It merges with the gas and becomes return gas. In addition, the gas heading to the JT valve 16 is transferred to the heat exchanger 1l b
- 11e exchanges heat with the return gas, is cooled, expands with the JT valve 16, and partially liquefies.

The liquefied helium is gasified under the heat load of the cooling load I, becomes a return gas together with the gas that has not been liquefied, is heat-recovered in the heat exchangers 11e to 111, and returns to the input side of the compressor 3.

Additionally, in this device, a high pressure regulator 7. is used to control the discharge pressure of the compressor 3. It is controlled by a pressure regulating valve 5.

Further, the turbine bearing gas supply line 15 is connected to the high pressure line l, and the turbine bearing gas supply valve 16.
Expansion turbine 13 at a preset pressure by 18
Bearing gas is supplied to a and 13b.

The bearing gas outlet line is maintained at the pressure in the turbine bearing chamber by a regulating valve 17.19.

In the apparatus configured as described above, the cold box inlet valve 9
If the cold box is opened suddenly, a large amount of flow will flow into the cold box.
The discharge output pressure of the compressor 3 cannot be followed by the high pressure regulator 7 and the pressure regulating valve 5 alone, resulting in a pressure drop. As a result, the turbine bearing gas supply pressure also decreases, leading to damage to the turbine bearings. For this reason, a speed controller is installed at the cold box inlet valve 7 to prevent a sudden pressure drop and to measure the stability of the turbine bearing gas pressure.

According to this embodiment, the pressure in the high pressure line at the time of startup can be kept constant, and the pressure in the turbine bearing gas supply line can be stabilized.

〔Effect of the invention〕

According to the present invention, it is possible to prevent excessive load fluctuations from being applied to the expansion turbine even in the event of an erroneous operation or malfunction, thereby improving reliability and operability.

[Brief explanation of drawings]

FIG. 1 is a system diagram showing a cryogenic refrigeration system having an expansion turbine which is an embodiment of the present invention, and FIG. 2 is a system diagram showing a cryogenic refrigeration system having an expansion turbine which is a second embodiment of the present invention. It is a diagram. 9...Cold box inlet valve, 12a, 12
b... Expansion turbine inlet valve with sudden opening prevention mechanism, 13 a
or 13c...expansion turbine, 14...
・・Sudden opening/sudden closing prevention mechanism'4l diagram/4-----1-Dosho mouth juice

Claims (1)

[Scope of Claims] 1. A cryogenic refrigeration system having an expansion turbine and an expansion turbine inlet valve, characterized in that the expansion turbine inlet valve is provided with means for gently opening it. 2. A cryogenic refrigeration system having an expansion turbine and an expansion turbine outlet valve, characterized in that the expansion turbine outlet valve is provided with means for gently opening and closing the expansion turbine. 3. A cryogenic refrigeration system having an expansion turbine, an expansion turbine inlet valve, and an expansion turbine outlet valve, characterized in that the expansion turbine inlet valve is provided with means for gently opening, and the expansion turbine outlet valve is provided with means for gently opening and closing. A cryogenic refrigeration system with an expansion turbine. 4. A cryogenic refrigeration apparatus having an expansion turbine, characterized in that the cold box inlet valve is provided with means for gently opening.