JPH0345862A - cryogenic cooling equipment - Google Patents

Abstract

PURPOSE:To utilize efficiently an auxiliary cold source for precooling of a freezing device without uselessly discharging the auxiliary cold source by a method wherein a part of a refrigerant for precooling is branched to the heat shield side of a body to be cooled, and a refrigerant for precooling after cooling of the heat shield is joined with a refrigerant for precooling refrigerant gas. CONSTITUTION:A body 7 to be cooled is placed in a vacuum heat insulating container 8. In order to relieve a heat load on liquid helium, a heat insulating shield plate 9 of a liquid nitrogen temperature level (approximate 80K) is arranged in the vacuum heat insulating layer of the vacuum heat insulating container 8, and the feed of liquid nitrogen to the heat insulating shield plate 9 is effected through liquid nitrogen pipings 10 and 12. In order to maintain the temperature of the heat insulating shield plate 9 at a low value, the temperature of the outlet of a nitrogen piping 13 is kept at an enough low value, and low temperature nitrogen gas is accompanied by a liquid nitrogen mist. The low temperature nitrogen gas accompanied by the liquid nitrogen mist flows through a nitrogen piping 13 and is joined with a liquid nitrogen feed piping 11 to the cold box side. The low temperature nitrogen gas is fed to a cold box 2, and heat-exchanges with helium gas at a heat exchanger 3, the temperature of the nitrogen gas is increased approximately to an ordinary value at a nitrogen outlet piping 14 and released to the open air.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a cryogenic cooling device, and more particularly to a suitable cryogenic cooling device (using an auxiliary cold source).

[Conventional technology]

An example of a conventional device will be explained with reference to FIG.

′! In Figure J4, the helium gas compressed by the compressor 1 enters the cold box 2 and exchanges heat with the return helium gas and pre-cooling liquid nitrogen in the heat exchanger 3, and then part of it is transferred to the expansion turbine 4. , insulation 11*u, generates cold, becomes low-pressure helium gas, and returns to the suction side of the compressor l. Some of the other gases further undergo heat exchange in the heat exchanger 3, and after the temperature drops, they are expanded in the JT valve (Joule-Thomson, MGK valve) 5, and a part of the gas becomes liquid. Then, the heat insulated vacuum pipe 6 is worn out and the heat is sent to the object 7 to be cooled, such as a superconducting magnet. The low-temperature helium that cools the object to be cooled and evaporates returns to the cold box 2 through the insulated vacuum piping 6, and further reaches the suction side of the compressor 1.

On the other hand, the object to be cooled 7 is placed inside the vacuum insulation container 8,
In order to reduce the heat load on the liquid helium, the liquid nitrogen temperature level (approximately 80K) is maintained within the vacuum insulation layer of the vacuum insulation container 8.
) is installed. Liquid nitrogen is supplied to the heat insulating shield plate through liquid nitrogen piping 10. This is done through the following steps. In order to maintain the temperature of the heat insulating shield plate 9 at a low temperature, the nitrogen pipe outlet 13 must also be maintained at a sufficiently low temperature, and numerically the liquid nitrogen mist is entrained and released into the atmosphere. In addition, the liquid nitrogen used for pre-cooling of the helium refrigerator is the liquid nitrogen pipe 10. and 11 are then supplied to the cold box 2, where they exchange heat with helium gas in the heat exchanger 3, and at the nitrogen outlet pipe 14, the temperature reaches almost normal temperature and is released into the atmosphere.

Related systems of this type include "Cooling System for Superconducting Quadrupole Electromagnet for Tristan (2)" by Ouchi et al., Preliminary Collection of the 1989 Spring Cryogenic Engineering Presentation Conference, B1-3.
J.P. 25 (1989), etc.

[Problem to be solved by the invention]

The above conventional technology does not take into consideration the effective use of liquid nitrogen, which is an auxiliary cooling source, and the liquid nitrogen is discharged as it is after cooling the insulation shield plate, and the cooling power of liquid nitrogen is not fully utilized. , there was a waste in that the unit price of the system deteriorated.

A first object of the present invention is to provide a cryogenic cooling device that can effectively utilize an auxiliary cold source.

A second object of the present invention is to provide a cryogenic cooling device that can effectively cool a refrigerator and an object to be cooled in accordance with their respective operations.

A third object of the present invention is to provide a cryogenic cooling device that can operate stably.

[Means to solve the problem]

In order to achieve the above first objective, in a cryogenic cooling apparatus that adiabatically expands a refrigerant gas to generate a cryogenic cold substance and cools an object to be cooled with the cryogenic refrigerant, a pre-cooling device for pre-cooling the refrigerant gas is provided. A part of the refrigerant is branched to the heat shield side of the object to be cooled, and the pre-cooling refrigerant after cooling the heat shield is merged with the pre-cooling refrigerant of the refrigerant gas.

Upper tel! Refrigeration involves adiabatic expansion of refrigerant gas to produce cryogenic refrigerant in order to achieve the second objective! With kll.

A cooled part having the generated cryogenic refrigerant, a heat shield provided in the cooled part to prevent heat from entering the cryogenic coolant, and the freezing! a refrigerant supply source of a pre-cooling refrigerant for pre-cooling the refrigerant gas located at &, a means for branching a part of the pre-cooling refrigerant from the refrigerant supply source to the heat shield body, and a means for supplying the pre-cooling refrigerant from the refrigerant supply source to the heat shield body; Is the pre-cooling refrigerant from the above order? 1
a means for supplying the precooling refrigerant to the precooling section of the apparatus; a means for discharging the precooling refrigerant from the heat shield body; and a means for switching between the supply and discharge of the precooling refrigerant from the heat shield body. This is what I did.

In order to couple the purpose of gJ3 above, there is provided a refrigeration device for raw refrigerant gas, a cooled part having the generated cryogenic refrigerant, and a cooling part provided in the cooled part to prevent heat from entering the cryogenic refrigerant. a refrigerant supply source for a precooling refrigerant that precools the refrigerant gas of the refrigeration device, and a means for branching a part of the precooling refrigerant from the refrigerant supply source to the heat shield body. a means for supplying a pre-cooling refrigerant from the heat shield body portion to a pre-cooling section of the refrigeration apparatus; and a means for separating the supplied pre-cooling refrigerant from the pre-cooling refrigerant directly supplied from the refrigerant supply source into a gas-liquid state. and supplying means.

[For production]

If the pre-cooling refrigerant discharged from the heat shield of the object to be cooled is released directly into the atmosphere, it will lose its coldness, but by using it as a pre-cooling cold in the refrigeration equipment, it can be cooled down to almost room temperature by 1.
1ilF! can be recovered, making effective use of cold weather.

In addition, when the heat shield is precooling at a relatively high temperature, the heat shield outlet temperature is high, and if it is supplied to the refrigeration equipment as it is, there is a risk of destroying the temperature balance of the refrigeration equipment, but a switching means is provided at the heat shield exit. As a result, the high-temperature precooling refrigerant can be disposed of into the atmosphere without being supplied to the refrigeration system, thereby improving the controllability of the refrigeration system.

Furthermore, by providing the refrigeration system with gas-liquid separation for the current cooling refrigerant, the refrigeration system can be stably precooled without being affected by the precooling refrigerant after cooling the heat shield plate.

〔Example〕

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

! In diagram J1, l is a compressor that boosts and circulates refrigerant gas, such as helium gas, 2 is a vacuum-insulated cold box, and 3 is a multi-stage heat exchanger (the installation range is shown because it is omitted). , 4 is an expansion turbine for cold generation, 5 is a JT valve for generating cryogenic refrigerant, 6 is an insulated vacuum pipe connecting the cold box and the vacuum insulated container 8, and 7 is a cooled object housed in the vacuum insulated container 8. 9 is a heat insulating shield plate that prevents heat from entering the object to be cooled 7; 10 is a pipe for supplying a pre-cooled refrigerant, for example, liquid nitrogen; 2 is connected to the pipe 10 via a valve and connected to the heat exchanger 3; 13 is a pipe connected from the heat insulating shield plate 9 to the pipe 11, and 16 is a valve provided in the pipe U.

With the above configuration, the helium gas compressed by the compressor 1 enters the cold box 2, and after exchanging heat with the return helium gas and the pre-cooling liquid Ms in the heat exchanger 3, a part of the helium gas is transferred to the expansion turbine. 4, it expands adiabatically, generates cold, becomes low-pressure helium gas, and returns to the suction side of compression 1al. Some of the other gases are further heat-exchanged in a heat exchanger 3, and when the temperature has decreased, they are expanded in a JT valve (Joule-Thomson expansion valve) 5, and a part of the gas is liquefied, which is then heated in an insulated vacuum pipe 6. It is then sent to a cooled object 7 such as a superconducting magnet. The low-temperature helium that cools the object 7 and evaporates returns to the cold box 2 through the adiabatic vacuum piping 6, and further reaches the suction side of the compression ill.

On the other hand, the object to be cooled 7 is placed inside the vacuum insulation container 8,
In order to reduce the heat load on the liquid helium, the liquid nitrogen temperature level (approximately 80K) is maintained within the vacuum insulation layer of the vacuum insulation container 8.
) is installed. Liquid nitrogen is supplied to the heat insulating shield plate 9 through liquid nitrogen piping 10. This is done through the following steps. In order to maintain the temperature of the heat insulating shield plate 9 at a low temperature, the outlet of the nitrogen pipe 13 must also be maintained at a sufficiently low temperature, thereby entraining the liquid nitrogen mist.

The low-temperature nitrogen gas accompanied by the liquid nitrogen mist passes through the nitrogen pipe 13, joins the liquid nitrogen supply pipe 11 to the cold box side, is supplied to the cold box 2, and is heat exchanged with helium gas in the heat exchanger 3. However, in the nitrogen outlet pipe 14, the temperature reaches almost room temperature and is released into the atmosphere.

According to this embodiment, the cooling of the liquid nitrogen and low-temperature nitrogen gas after cooling the heat insulating shield plate 9, including sensible heat, can be effectively used for pre-cooling the helium refrigerator, so overall the consumption of liquid nitrogen can be reduced. It has the economic effect of reducing

A second embodiment of the present invention will be described below.

In Figure 182, the same symbols as in Figure 1 indicate the same members,
Omit the explanation. The difference between this figure and FIG. 1 is that a three-way valve 17 is provided in the middle of the nitrogen pipe 13, and one side is on the atmosphere discharge side.

With the above configuration, the N element coming out from the heat insulating shield plate 9 is
During precooling when the temperature is high, the three-way valve 17 releases the air to the atmosphere and does not send it to the cold box 2 side. When the temperature of the nitrogen discharged from the heat insulating shield plate 9 falls, the three-way valve 17 is switched to the cold box 2 side and used for pre-cooling the cold box 2.

According to this embodiment, the same effects as in the previous embodiment can be obtained, and the temperature on the cold box 2 side and the temperature on the cooled object 7 side can be managed and operated independently, so that operational controllability is improved. There is an effect.

In addition, automating the opening and closing of the three-way valve depending on the nitrogen temperature,
It is equally effective to replace the three-way valve with two two-way valves so that the flow can flow to the atmosphere side and to the cold box side, respectively, so that the flow rate can be controlled.

FIG. 3 shows a third embodiment of the invention.

In FIG. 3, the same reference numerals as in FIGS. 1 and 2 indicate the same members, and their explanations will be omitted. The difference between this figure and FIG. 2 is that a gas-liquid separation 1ii18 is provided before the nitrogen pipe 11 enters the heat exchanger 3, and the gas side is connected to the high temperature side of the heat exchanger 3, and the liquid side is connected to the heat exchanger 3. In addition, in the liquid nitrogen precooling of the cold box 2,
The point is that the liquid level of the gas-liquid separator 18 that separates liquid nitrogen and gaseous nitrogen is controlled (not shown) to supply an appropriate amount of liquid nitrogen.

The amount of liquid nitrogen mist coming out of the nitrogen pipe 13 of the heat insulating shield plate 9 varies depending on the operating status of the object to be cooled 7, but it cannot be directly determined by temperature measurement, and the temperature of the helium cold box varies. Although the detection will be delayed due to the distribution, by providing the gas-liquid separation R18 and controlling the liquid level, the liquid nitrogen precooling of the cold box can be performed stably and operation control becomes easier.

In addition, the heat exchanger 3 can be effectively precooled in the gas and fluid parts of the gas-liquid separator 18, thereby further improving the precooling efficiency and making it possible to efficiently use liquid nitrogen, which is a refrigerant for precooling. becomes.

As described above, according to this embodiment, the previous l! eThe above effects can be obtained in accordance with the effects of the second embodiment.

In addition, in this figure, a temperature detector 19 is provided in the piping 13, and a control device is installed! In addition, a detection signal is inputted to enable automatic control of the three-way valve 17 by the control device.
It is also possible to provide information on the refrigeration system side to 20, such as stop, etc., and to switch and control the three-way valve 17 so as not to flow to the piping 11 side.

In addition, in these examples, the heat shield plate of the object to be cooled was described for the use of liquid nitrogen for pre-cooling, but the same effect is expected when applied to the heat shield of the cold transfer pipe of the insulated vacuum pipe 6, etc. It goes without saying that it can be done.

〔Effect of the invention〕

According to the present invention, the auxiliary cold source can be effectively used for precooling the refrigeration device without being wastefully discharged, and there is an economical effect that the consumption amount of the auxiliary cold source can be reduced as a whole.

Furthermore, the provision of the switching means has the effect of improving operational controllability since the temperatures of the object to be cooled and the cold box can be managed and operated independently.

Furthermore, by installing the gas-liquid separator in the cold box, there is an effect in terms of operation control that precooling of the cold box can be carried out stably.

[Brief explanation of drawings]

FIG. 1 is a flow diagram showing a cryogenic cooling device which is an embodiment of the present invention, FIG. 2 is a flow diagram showing a cryogenic cooling device which is a second embodiment of the present invention, and FIG. FIG. 4 is a flowchart showing a cryogenic cooling device according to a third embodiment of the invention, and FIG. 4 is a flowchart showing a conventional device. 1...Compressor, 2...-cold box, 3...Heat exchanger, 7...Object to be cooled, 8...
...Vacuum insulation container, 9...Insulation shield plate, 10.11.12.13...Piping, 1 Fig. 15, 7... P-body

Claims (1)

[Claims] 1. In a cryogenic cooling device that adiabatically expands a refrigerant gas to generate a cryogenic refrigerant and cools an object to be cooled with the cryogenic refrigerant, one of the pre-cooling refrigerants that pre-cools the refrigerant gas. A cryogenic cooling device characterized in that a portion is branched to the heat shield side of the object to be cooled, and the precooling refrigerant after cooling the heat shield is merged with the precooling refrigerant of the refrigerant gas. 2. The cryogenic cooling device according to claim 1, further comprising means for branching the precooling refrigerant after cooling the heat shield to the discharge side. 3. The cryogenic cooling device according to claim 1, further comprising a gas-liquid separator on the refrigerant gas side of the pre-cooling refrigerant. 4. A refrigeration device that adiabatically expands refrigerant gas to generate a cryogenic refrigerant, a cooled part having the generated cryogenic refrigerant, and a cooling device installed in the cooled part to prevent heat from penetrating into the cryogenic refrigerant. a heat shield body, a refrigerant supply source of a pre-cooling refrigerant that pre-cools the refrigerant gas of the refrigeration device, and means for branching a part of the pre-cooling refrigerant from the refrigerant supply source to the heat shield body part; , a means for supplying a pre-cooling refrigerant from the heat shield body to a pre-cooling section of the refrigeration apparatus, a means for discharging the pre-cooling refrigerant from the heat shield body, and a pre-cooling refrigerant from the heat shield body. and means for switching between said supply and said discharge. 5. A refrigeration device that adiabatically expands refrigerant gas to generate a cryogenic refrigerant, a cooled part having the generated cryogenic refrigerant, and a cooling device installed in the cooled part to prevent heat from entering the cryogenic coolant. a heat shield body, a refrigerant supply source of a pre-cooling refrigerant that pre-cools the refrigerant gas of the refrigeration device, and means for branching a part of the pre-cooling refrigerant from the refrigerant supply source to the heat shield body part; , a means for supplying a pre-cooling cold plate from the heat shield body portion to a pre-cooling section of the refrigeration apparatus, and a gas-liquid separation means for separating the supplied pre-cooling refrigerant from the pre-cooling refrigerant directly supplied from the refrigerant supply source. A cryogenic cooling device characterized by comprising: means for supplying