JPH05322343A - Freezer device with reservoir tank - Google Patents

Abstract

PURPOSE:To provide a freezer device capable of adjusting a helium gas flow rate of a cold heat generating circuit and a J-T circuit separately in response to a thermal load of a cooled item in the most suitable manner within a short period of time and further capable of performing an efficient and convenient operation. CONSTITUTION:A cold heat generating circuit and a J-T circuit are provided with a reservoir tank 21a and a reservoir tank 21b, separately, and then a helium gas flow rate for the cold heat generating circuit and a helium gas flow rate for J-T circuit are controlled separately, thereby an amount of refrigerant and a liquifying amount for the freezer device are controlled. A freezing amount and a liquifying amount of the freezer device are controlled at a temperature of about 4.5K at an outlet of a J-T 13 valve and then the freezing amount and liquefying amount corresponding to the thermal load can be generated stably, within a short period of time, efficiently and conveniently.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cryogenic refrigerating apparatus, and more particularly to a refrigerating apparatus in which the refrigerating amount and the liquefying amount can be arbitrarily and efficiently adjusted.

[0002]

2. Description of the Related Art Various electronic devices such as a nuclear magnetic resonance diagnostic device using a superconducting magnet, a thermophysical property measuring device, a Josephson element and various sensors, a high vacuum and a high pumping speed cryopump, and a superconducting magnet are used. Cryogenic liquid helium is used as the coolant for the electron accelerator and the synchrotron radiation generator. Liquid helium as a refrigerant evaporates with a little heat,
Moreover, since it is expensive, a refrigerating device for condensing the evaporated helium gas is installed.

However, the heat load on the object to be cooled of the above-mentioned device, for example, the liquid helium container containing the superconducting magnet or the like is often varied at all times, and the refrigerating amount of the refrigerating device is also adjusted according to the heat load. This reduces the power consumption of the refrigeration system and improves the operating efficiency.

In this refrigeration system, helium gas pressurized by a two-stage compressor unit is used as a cold generator for precooling, an expansion turbine, a Claude type reciprocating expander, and a Gifford-McMahon (GM) type reciprocating motion. Type cooling machine using a type expander and the high pressure flow path of the Joule-Thomson circuit (JT circuit) having the Joule-Thomson valve (JT valve) in the cryogenic part are supplied by the same pipe, and the pre-cooling is performed. The exhaust helium gas of the cold generator for the vehicle is returned to the medium pressure line of the compressor unit arranged in the two stages, and the exhaust helium gas of the JT circuit is returned to the low pressure line of the compressor unit arranged in the two stages. The method is described in JP-A-1-159568.

In this case, according to the heat load of the object to be cooled,
The high pressure and low pressure pipes at room temperature of the refrigeration system are connected to at least one of the high pressure and low pressure pipes via a flow control valve into and out of a reservoir gas tank, and a portion of the high pressure gas flow rate of the high pressure gas circulating in the refrigeration system is taken in and out. Adjust gas flow rate to operate efficiently.

At this time, since the cold generating circuit and the J / T circuit are configured so that the two-stage compressor is used for two circuits in the same flow path, the helium gas flow rates of the cold generating circuit and the J / T circuit are Both will change.

Therefore, if the flow rate on the expander side is increased or decreased, the flow rate passing through the J.T valve also changes, and complicated adjustment is required to reach the optimum heat balance state. Therefore, the distribution operation for optimally distributing the adjusted high-pressure gas flow rate is simplified.

[0008]

However, as described above, the conventional technique does not mention a method of cooling while separately adjusting the helium gas flow rates of the cold generation circuit and the JT circuit. In addition, the cold generation circuit and JT
The operating pressure of the circuit is different. Also, the reservoir tank controlled to the appropriate pressure for the circuit is not installed.

An object of the present invention is to optimize the refrigeration system efficiently by separately adjusting the helium gas flow rates of the cold generation circuit and the JT circuit in a short time in response to the heat load of the object to be cooled. The object of the present invention is to provide a refrigeration system that can be operated at any time.

[0010]

[Means for Solving the Problems] The above object is to dispose separate compressors in a cold generation circuit and a J.T circuit having different operating pressures, and in at least one of the high-pressure and low-pressure pipes at normal temperatures, A separate gas reservoir tank that communicates via a pressure control valve is provided separately, and the cold generation circuit in the refrigeration system and the J
This is achieved by taking in and out a part of the high-pressure gas flow rate circulating in the T circuit and supplying an appropriate high-pressure gas flow rate to both circuits.

The refrigerating apparatus with a reservoir tank according to the present invention is
A cold generating circuit including a cold generating means for precooling and a first gas compression means for supplying a first working medium to the cold generating means, a freezing generating means for freezing or liquefaction, and a second operation for the freezing generating means. A refrigeration generating circuit including a second gas compressing means for supplying a medium, wherein (1) at least a working medium storing means for taking in and out a first working medium via a valve communicates with the first gas compressing means. What you did, (2) First
The first working medium storage means for taking in and out the working medium via the valve communicates with the first gas compression means, and the second working medium storage means for taking the second working medium in and out via the valve is the second gas compression means. Or (3) a first working medium storage means for taking in and out the first working medium via a valve is communicated with the first gas compression means, and a second working medium is taken in and out via the valve The working medium storage means is communicated with the second gas compression means, and the first and second working medium storage means are communicated with each other via a valve.

The refrigerating apparatus with a reservoir tank according to the present invention is provided with a cold generating circuit including a cold generating means and a gas compression means for supplying a working medium to the cold generating means, and the working medium is taken in and out via a valve. The working medium storage means for communicating with the gas compression means.

In each of the above inventions, (1) adjusting the amounts of the first and second working media passing through the valve group according to the temperature, pressure, and heat load in the refrigeration system, and (2) generation of cold. It is preferable that the circuit and the refrigeration generation circuit can be arbitrarily isolated, and (3) the amount of working medium passing through the valve group can be adjusted according to the temperature, pressure, and heat load in the refrigeration system.

[0014]

When a Gifford-McMahon (GM) reciprocating expander is used as the cold generator for pre-cooling and the refrigerating device is configured by the JT circuit separated from the cold generating circuit for pre-cooling, The high-pressure gas flow rate of both circuits controls the gas hold amount of the reservoir gas tanks arranged in the closed circuits to arbitrary values, and controls the gas flow rate and operating pressure in both circuits to appropriate values within a short time. Thereby, J
A refrigerating device that controls the refrigerating amount at a temperature of about 4.5 K at the outlet of the T valve to stably generate the refrigerating amount corresponding to the heat load in a short time, efficiently and simply.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG.

The cold generator 1 arranged in the cold generating circuit for precooling is composed of, for example, a Gifford-McMahon expander. Pressure of about 20a of helium compressor unit 2 consisting of compressor, aftercooler and oil separator (not shown)
The high-pressure gas at tm flows into the cold generator 1 and adiabatically expands inside, generating cold at temperatures of about 40K and 15K at the first stage 3 and the second stage 4, respectively.

The expanded gas at a pressure of about 5 atm is again
Return to compressor unit 2. On the other hand, a high pressure of about 16 atm pressurized by a compressor unit 5 including a JT circuit compressor for liquefaction, an aftercooler, and an oil separator (not shown) separated from the cold generation circuit for precooling. Helium gas is
Pass through the high-pressure pipe 16a and the first heat exchanger 6, the heat exchanger 7, the second heat exchanger 8, the first adsorber 9, the heat exchanger 10, the third heat exchanger 11, and the second adsorber 12. The temperature is cooled to about 6K or less, adiabatic expansion is performed by the Joule-Thomson valve (hereinafter referred to as JT valve) 13, a part of the gas is liquefied, and it is accumulated in the liquid helium tank 14 to cool the object to be cooled such as the superconducting magnet 15 To do.

Unliquefied helium gas having a pressure of about 1.2 atm and vaporized gas of liquid helium 17 flow into the low-pressure pipe 16b, and the third heat exchanger 11, the second heat exchanger 8, the first heat exchanger 6 , It becomes almost room temperature, and the compressor unit 5
Return to.

The high-pressure pipe 19a and the low-pressure pipe 19b of the compressor unit 2 have a pressure adjusting valve 20a, a pressure adjusting valve 20b and a bypass valve 20 which are controlled by the internal pressure of the high-pressure pipe 19a.
It communicates with the reservoir tank 21a through the valve c and the valve 20d. A safety valve 22a is arranged in the high pressure pipe 19a.

The high-pressure pipe 16a and the low-pressure pipe 16b of the compressor unit 5 communicate with the reservoir tank 21b via a pressure adjusting valve 23a and a pressure adjusting valve 23b controlled by the internal pressure of the low-pressure pipe 16b. A safety valve 22b is arranged in the high pressure pipe 16a.

The liquid level of the liquid helium tank 14 is measured by the temperature and liquid level gauge 24, and the measurement signal is input to the signal processing / control device 26 via the measurement line 25. Here, each control valve, the bypass valve, the JT valve, and the operating frequency controllers 27a and 27b of each compressor unit are controlled according to the measured value and the processed value.

The interior of the cryostat 18 is vacuum-insulated. Impurities in the helium gas are removed in each adsorber. The refrigeration system has the above configuration.

The operation procedure of the control valve around the reservoir tank, the bypass valve, the JT valve, and the operating frequency controller of each compressor unit will be described below.

The operation of the refrigeration system is started when the refrigeration system including the object to be cooled is in a normal temperature state. First, the cold generator 1 of the cold generating circuit for precooling is in a normal temperature state, and helium gas cannot be sucked into the cold generator so much. Therefore, the discharge pressure of the positive displacement type and constant compression ratio type helium compressor unit 2 is higher than the pressure in the low temperature steady state.

In this pressure state, the suction pressure also increases and the differential pressure between the suction pressure and the discharge pressure of the compressor unit 2 increases. As a result, the amount of cold generation in the first stage 3 and the second stage 4 of the cold generator 1 that adiabatically expands under this differential pressure condition increases. However, the temperature of each stage is higher than the temperature during the liquefaction operation.

On the other hand, the high-pressure helium gas pressurized by the compressor unit 5 and having a pressure of about 16 atm is supplied to the high-pressure pipe 16a.
Through the heat exchanger 7 and the heat exchanger 10 of the cold generator 1.
The stage 3 and the second stage 4 are cooled by the cold, and the second heat exchanger 8, the first adsorber 9, the third heat exchanger 11 and the second heat exchanger 8 are cooled.
The adsorber 12, the J · T valve 13, the liquid helium tank 14, the superconducting magnet 15, and the first heat exchanger 6 are sequentially cooled, and the temperature is gradually lowered. As the temperature of the refrigerating apparatus decreases, in the conventional cold generator, the suction amount of helium gas increases, and if gas is not replenished, the discharge pressure of the positive displacement type and constant compression ratio type helium compressor units 2 is: It decreases gradually. In this pressure state, the suction pressure also decreases, and the differential pressure between the suction pressure and the discharge pressure of the compressor unit 2 decreases. As a result, the amount of cold generation in the first stage 3 and the second stage 4 of the cold generator 1 that undergoes adiabatic expansion under this differential pressure condition sequentially decreases. As a result, the cooling rate of the refrigeration system is reduced, and rapid precooling operation cannot be performed.

Here, the pressure adjusting valve 20b and the valve 20d are opened by sensing the decrease in the internal pressure of the high-pressure pipe 19a, and the insufficient helium gas is replenished from the medium-pressure reservoir tank 21a to the suction side of the compressor unit 2. , The discharge pressure is maintained at a predetermined value to prevent a reduction in cold generation. At this time, the operating frequency controller 27b further controls the compressor unit 2
If the operating frequency is increased, the amount of cold generation further increases, and it is possible to prevent the amount of cold generation from decreasing. These driving operations are controlled by the signal processing / control device 26.

Further, as the temperature of the refrigerating apparatus lowers, the gas holding amount of the liquefaction circuit increases, and if there is no gas replenishment, the discharge pressure of the positive displacement type and the constant compression ratio type helium compressor units 5 will be in order. descend.

In this pressure state, the suction pressure becomes low and the predetermined pressure cannot be maintained. Therefore, the low pressure pipe 16
The pressure adjusting valve 23b is opened upon detecting the decrease in the internal pressure of b, and the insufficient helium gas is replenished from the medium pressure reservoir tank 21b to the suction side of the compressor unit 5 to maintain the suction pressure at a predetermined value.

When the temperature at the inlet of the J · T valve 13 reaches about 20K, the J after the adiabatic expansion is caused by the Joule-Thomson effect.
・ T valve outlet temperature becomes lower than inlet temperature, and cooling rate becomes faster. When the temperature at the J / T valve 13 inlet reaches about 6K,
Part of the gas after adiabatic expansion is liquefied and the liquid helium tank 14
Liquid helium begins to collect in.

Since liquid helium must be accumulated rapidly until the superconducting magnet 15 is covered, if the operating frequency controller 27a further increases the operating frequency of the compressor unit 2 at this time, the flow rate of the liquefaction circuit increases. Further, the liquefied amount is further increased, and a predetermined amount of liquid helium can be accumulated within a short time. If helium is liquefied at this time, low-pressure pipe 1
Since the amount of helium returned in 6b is reduced, the internal pressure of the low-pressure pipe 16b is reduced, and the pressure adjustment valve 23b is opened by detecting this decrease, and the insufficient helium gas is discharged from the medium pressure reservoir tank 21b to the compressor unit. Supply to the suction side of 5,
Hold the suction pressure at a predetermined value.

After the predetermined liquid helium is stored up to the predetermined temperature and the liquid surface, the signal processing / control device 26 shifts to the refrigerating operation state necessary for maintaining the liquid surface to save the operation power consumption. That is, the operating frequencies of the compressor units 2 and 5 are reduced by the operating frequency controllers 27a and 27b to reduce the discharge gas flow rate, and if necessary, the valve 20d is further closed and the bypass valve 20c is opened so that the compressor is closed. The helium gas in the unit 2 is returned to the medium pressure reservoir tank 21a by a predetermined amount to reduce the suction pressure and further reduce the discharge gas flow rate.

On the other hand, when the heat load temporarily increases due to an increase in the amount of heat entering the liquid helium tank 14 or an increase in heat generation of the superconducting magnet 15, the liquid helium level decreases and the amount of liquid helium vaporized further. Is increased, the pressure in the low pressure pipe 16b is increased. In the driving operation in this case, the pressure adjusting valve 23a is quickly opened, the gas in the J.T circuit for liquefaction returns to the reservoir tank 21b, and the suction pressure is lowered. Further, the signal processing / control device 26 reduces the discharge gas flow rate. Further, under the control of the signal processing / control device 26, the operating frequencies of the compressor units 2 and 5 are increased by the operating frequency controllers 27a and 27b to increase the liquefaction amount.

If necessary, the valve 20d is further opened and the bypass valve 20c is closed to supply the helium gas of the compressor unit 2 from the medium pressure reservoir tank 21a to the compressor unit 2 to increase the suction pressure, Further, it is possible to return the liquid to a predetermined liquid level within a short time in which the amount of cold generation can be increased and the amount of liquefaction can be increased.

At the start of the refrigeration system, the bypass valve 20d is closed and the bypass valve 20c is opened, so that the helium gas in the compressor unit 2 is stored in the medium-pressure reservoir tank 21a.
The initial rotational compression load is smaller when the suction pressure is reduced by returning the predetermined amount to the predetermined value.

By separating the cold generating circuit from the reservoir tanks 21a and 21b of the JT circuit, it is possible to prevent the components such as the superconducting magnet 15 from being mixed with impurities such as adhesive outgas. Therefore, the operational reliability of the cold generator can be improved.

The minimum required pressure of the reservoir tank 21b may be 1.2 atm.
The minimum required pressure of a is about 5.5 atm. Therefore, by isolating the reservoir tanks 21a and 21b and setting the pressures to predetermined values, the compressor unit can be stably replenished with gas, and a stable and appropriate refrigeration amount of the refrigeration system can be secured.

As described above, according to the present embodiment, the high-pressure gas flow rate of the JT circuit isolated from the cold generation circuit for precooling can be controlled to an appropriate value separately within a short time. As a result, in the refrigeration apparatus, the precooling time is short, the refrigeration amount and the liquefaction amount at the J.T valve outlet temperature of about 4.5K are controlled, and the refrigeration amount and the liquefaction amount corresponding to the heat load are stably and It can be efficiently and simply generated within a short time, and the compressor input electric power amount per unit refrigeration amount can be small.

Further, according to this embodiment, since the reservoir tank of the JT circuit which is isolated from the cold generation circuit for precooling can be isolated, the reservoir tank can be filled with the impure gas generated from the cooled object in the JT circuit. Since the inside of the cold generation circuit for pre-cooling is not contaminated via the cold cooling circuit, the cold generator in the cold generation circuit is free from troubles due to impure gas, and there is an effect that a highly reliable refrigeration system can be provided. In this case, both reservoir tanks may be connected via a valve as needed.

In the present embodiment, the cold generator has G / M.
Although the example in which the cycle expander is applied has been described, the same effect can be obtained even in the refrigeration cycle and the Brayton cycle to which the Solvay cycle, the Stirling cycle, the Villemeier cycle, the turbine type, and the Claude type expander are applied. Further, the cold generation stage of the cold generation circuit for precooling may have three or more stages, and the same effect can be obtained even if the J / T valve of the J / T circuit has two or more stages.

In the present embodiment, the case where the superconducting magnet is used as the cooled object has been described. However, various electronic devices such as Josephson elements and various sensors, and a cryopanel having a high vacuum and a high evacuation speed are cooled. However, it has the same effect.

Further, in this embodiment, the increase and decrease of the refrigeration amount and the liquefaction amount were controlled with reference to the liquid level of liquid helium. However, if the liquid level is vibrating, an accurate liquid level can be obtained with a liquid level gauge. Since it cannot be detected, in that case, the pressure in the J / T circuit low-pressure pipe or J
・ Refrigeration amount based on the internal pressure of the reservoir tank of the T circuit,
Even if the increase / decrease of the liquefaction amount is controlled, the same effect can be obtained.

In this embodiment, the case where the cold generation circuit for pre-cooling and the reservoir tank of the J.T circuit are separated has been described. However, when the impure gas generated from the J.T circuit is very small. Even if the reservoir tanks of both circuits are shared by one tank, the same effect can be obtained.

Further, in this embodiment, the refrigerating apparatus having the cold generating circuit for precooling and the JT circuit has been described.
The same effect can be obtained with a refrigerating device including a cold generating circuit for precooling, a control valve communicating with the cold generating circuit, and a reservoir tank.

Further, in the present embodiment, the case of one refrigerating apparatus has been described, but when a plurality of refrigerating apparatuses are installed, the cold generating circuit for precooling and the JT circuit are shared with each other. Even if the reservoir tank of is arranged, the same effect can be obtained.

Further, in this embodiment, the cold generation circuit and J.
Although helium gas was used as the working fluid of the T circuit, helium gas was used as the working fluid of the cold generation circuit and nitrogen gas was used as the working fluid of the JT circuit.
It has the same effect except that the freezing temperature is different.

[0047]

According to the present invention, the high-pressure gas flow rate of the JT circuit isolated from the cold generation circuit for pre-cooling can be individually controlled within a short time to an appropriate value at which the refrigeration amount can be efficiently generated. .. As a result, the precooling time of the refrigeration system can be shortened, the refrigeration amount and liquefaction amount at the J / T valve outlet temperature of about 4.5K can be controlled, and the refrigeration amount and liquefaction amount corresponding to the heat load can be stably and shortened. There is an effect that it is possible to provide a refrigeration system that can be efficiently and simply generated within a time period and that requires only a small amount of compressor input power per unit refrigeration amount.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a configuration of a refrigerating apparatus according to an embodiment of the present invention.

[Explanation of symbols]

1 ... Cold generator 2, 5 ... Compressor unit, 21a, 2
1b ... Reservoir tank, 20a, 20b, 23a, 23
b ... flow control valve, 20c ... bypass valve, 20d ... valve,
6, 7, 8, 11, 12 ... Heat exchanger, 13 ... J · T valve,
17 ... Liquid helium, 15 ... Superconducting magnet.

Claims (7)

[Claims] 1. A cold generating circuit including a cold generating means for precooling and a first gas compression means for supplying a first working medium to the cold generating means, a freezing generating means for freezing or liquefying, and the freezing. A refrigerating apparatus provided with a refrigeration generating circuit including a second gas compressing means for supplying a second working medium to the generating means,
A refrigeration apparatus with a reservoir tank, characterized in that at least a working medium storage means for taking in and out a first working medium via a valve is connected to the first gas compression means. 2. A refrigeration system provided with a cold generation circuit including a cold generation means and a gas compression means for supplying a working medium to the cold generation means, and a working medium storage means for taking the working medium in and out through a valve. A refrigeration system with a reservoir tank, characterized in that it communicates with a gas compression means. 3. A cold generating circuit including a cold generating means for precooling and a first gas compression means for supplying a first working medium to the cold generating means, a freezing generating means for freezing or liquefying, and the freezing. A refrigerating apparatus provided with a refrigeration generating circuit including a second gas compressing means for supplying a second working medium to the generating means,
The second working medium storage means for communicating the first working medium storage means for loading and unloading the first working medium via the valve with the first gas compression means and the second working medium storage means for loading and unloading the second working medium for the second gas are provided. Refrigerating apparatus with a reservoir tank, which is in communication with the gas compressing means. 4. A cold generating circuit including a cold generating means for precooling and a first gas compression means for supplying a first working medium to the cold generating means, a freezing generating means for freezing or liquefying, and the freezing. A refrigerating apparatus provided with a refrigeration generating circuit including a second gas compressing means for supplying a second working medium to the generating means,
The second working medium storage means for communicating the first working medium storage means for loading and unloading the first working medium via the valve with the first gas compression means and the second working medium storage means for loading and unloading the second working medium for the second gas are provided. Refrigerating apparatus with a reservoir tank, wherein the first and second working medium storage means are communicated with each other via a valve. 5. The method according to any one of claims 1 to 4, wherein the first and second working medium amounts passing through the valve group are adjusted according to the temperature, pressure and heat load in the refrigeration system. Refrigerator with reservoir tank. 6. The refrigerating apparatus with a reservoir tank according to claim 1, wherein the cold generation circuit and the freezing generation circuit can be arbitrarily isolated. 7. The refrigerating apparatus with a reservoir tank according to claim 2, wherein the amount of the working medium passing through the valve group is adjusted according to the temperature, pressure and heat load in the refrigerating apparatus.