JPS61268972A - Method of controlling operation of helium liquefying and refrigerating device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for controlling the operation of a helium liquefaction building refrigeration system, and more specifically, the present invention relates to a method for controlling the operation of a helium liquefaction building refrigeration system, and in particular, it is possible to control the refrigeration output even when there is a sudden change in heat load in a cryogenic environment. Stable operating conditions without excess or deficiency! The present invention relates to a method for controlling the operation of a helium liquefaction/refrigeration system that maintains the amount of helium produced.

[Prior art] Helium (hereinafter referred to as "He") liquefaction/refrigeration equipment generates cold by isentropically expanding a portion of high-pressure He gas compressed to approximately 15 to 20 atmospheres using an expander. Using the cooling, the remaining He gas was precooled in stages to a predetermined low temperature (so-called inversion temperature) by heat exchange action, and then passed through a Joule-Thomson (hereinafter referred to as JT) valve to utilize the JT effect. The He gas is liquefied by the cooling action, and the temperature of the liquid He, that is, the extremely low temperature is obtained. If the liquid He obtained in this way is taken out as a product, it will become a liquefaction device, and on the other hand, the liquid He
The liquid He is circulated in a closed circuit without being taken out, and the MI heat of the liquid He is used to absorb the heat load of the object to be cooled in the cryogenic environment section (refrigeration load section), thereby reducing the temperature of the environment section. A type of system that maintains a constant value would be a refrigeration system. In other words, the difference between a refrigeration system and a liquefaction system is that in a liquefaction system, the low-pressure side He
(The gas flow rate on the return side 1(e) is high pressure side He (inlet side H
Compared to e), the gas flow rate is reduced by the amount of liquefaction, whereas in the refrigeration system, the liquefied He also evaporates and returns to the low-pressure side, so the He gas flow rates on the high-pressure side and the low-pressure side become equal. For this reason, the temperature distribution of the heat exchanger and expander within the equipment body is different between the liquefaction equipment and the refrigeration equipment, and their thermal design is only different.There is no essential difference in the structure of the equipment. do not have. Therefore, the He refrigerating device will be described below as a representative example.

As such a He refrigerating apparatus, one having a configuration as schematically shown in FIG. 3, for example, is known. That is, in FIG. 3, the refrigeration system 1 includes heat exchangers 5a to 5e, 1 expander 7a,
b. A device main body 2 in which a JT valve 6 and the like are built-in, a compressor 3 and an M-made device 4 connected to the population side of the main body 2. It consists of a cryogenic environment section 10 connected to the outlet side of the main body 2 of the device. After the He gas is pressurized by the pressure Li1 unit 3, it passes through the first to fifth heat exchangers 5a to 5e (hereinafter, this passage route is referred to as the "high pressure side route") and undergoes heat exchange. The mixture of He is partially liquefied by adiabatic expansion to near atmospheric pressure in the JT valve 6, and becomes He mist (hereinafter simply referred to as "liquid HeJ"). The mist is sent into the cryogenic environment section 10 from the mist supply pipe 8, and cools the atmosphere in the environment section 10 to a cryogenic temperature.Specific applications of the cryogenic environment section 10 include 1, for example, the production of metal materials at cryogenic temperatures. A typical example is a cryogenic fatigue testing device for examining mechanical properties.In this case, a condenser may be installed to re-condense the liquid He in the test device if it evaporates. can.

Now, the He gas vaporized by absorbing the heat of the object to be cooled existing in the cryogenic environment fI6to rises again in the opposite direction through the heat exchangers 5a to 5e of the device main body 2 (hereinafter, this passage route is referred to as the "low pressure side route"). He flowing through the high-pressure side path of the counterflow
After being cooled, it returns to the compressor 3 as He gas at room temperature and pressure. Furthermore, by circulating He through this path, the cryogenic environment section 10 is continuously kept at a cryogenic temperature. In such conventional He refrigerators, the throughput of the expander is manually adjusted to control the amount of cold generated by the expander, so when there is a change in load or when starting up, etc. , it was necessary to adjust the flow rate. Especially 1
In a refrigeration system (hereinafter referred to as a multi-user system) in which 81 cryogenic environment units (hereinafter referred to as users) are connected in parallel to one He refrigerator, the load fluctuates greatly, and appropriate expansion is required. If machine processing capacity is not adjusted, excess refrigeration can result in wasted energy. In addition, when the user stops cooling one unit (or two or more units) or starts cooling again during cooling operation, the operating conditions of the He refrigeration system change due to these operations, and the Manual operation requires a high degree of skill in order to maintain a constant temperature condition for the user during cooling operation.

Focusing on these circumstances, the Unreleased 151 is designed to maintain a constant user environment temperature while suppressing the generation of excessive cold in the tension machine, and in addition, in a multi-user system, the user As a result of conducting various researches in an attempt to provide a He liquefaction/refrigeration system that can appropriately stop and recool the cooling of the Helium without adversely affecting the operating conditions of other users, a patent application filed in 1983 was published.
We have developed the technology shown in No. 189i9!98.

That is, FIG. 4 is a schematic overall view showing the He refrigeration system according to the disclosed invention, in which 13 shows a temperature control controller, 14 shows a pressure controller, 15 shows a temperature measurement point, and 16 shows a pressure detection point.

A part of the high-pressure He gas in the system L2 on the He gas discharge side of the compressor 3 is cooled by the expanders 7a and 7b, and the remaining He gas cooled by this cold passes through the JT valve 6 and is subjected to the JT effect. generates He mist and cools the cryogenic environment section 10.
The atmosphere is cooled to an extremely low temperature. Here, expansion on the low temperature side @
A temperature measurement point 15 is provided downstream from the confluence of the He gas G discharged from 7b and the return gas G2 from the cryogenic environment section 1O, and the temperature measurement value at the temperature point 15 is input to the temperature control controller 13. The low temperature side expander 7
Adjust the processing amount of b. That is, if the measured temperature value is higher than the set value, it means that the amount of cold generated by the expander 7b is insufficient, so the temperature control controller 13 controls the expansion a7.
A command to increase the output is sent to the expander 7b to increase the throughput of the expander 7b, thereby increasing the amount of cold generation, thereby lowering the temperature at the temperature measuring point 15. On the other hand, if the measured temperature value is lower than the set value, it means that the amount of cold generated by the expander 7b is excessive, so the temperature control controller 13 sends a command to reduce the output to the expander 7b. The amount of processing is reduced to reduce the amount of cold generation, thereby increasing the temperature at the temperature measuring point 15. In this way, the temperature at the temperature measurement point 15 is maintained constant. As a result, in the heat exchanger 5d, the high pressure side He, which is a refrigerant,
The low pressure side H where the gas is a refrigerant with a constant set temperature
Since the e-gas provides a stable cooling effect, the temperature after heat exchange can be maintained at a predetermined temperature, and thereby the cryogenic environment section 10 is maintained at a constant temperature regardless of fluctuations in operating conditions. The temperature measurement point 15 shall be provided between the confluence point and the inlet of the heat exchanger immediately after (including the inlet).1 Between the confluence point and the temperature measurement point 15, the discharge gas G and the returned gas G2 are provided.
A mixer may be installed to improve mixing.

However, if the discharge amount of the compressor 3 is constant, the required power of the He refrigeration system will not change even if the throughput of the expansion a7b is changed according to the refrigeration load, and especially when the refrigeration load decreases, the energy source will change. Units decrease. In order to prevent this drop, in this He refrigeration system, the discharge pressure of the compressor 3 is set at the pressure detection point 1.
6, and the discharge amount of the compressor 3 is controlled by the pressure controller 14 to keep this pressure constant. If the refrigeration load decreases as a result, by throttling only the JT valve, the throughput of the expander 7b will decrease in accordance with the refrigeration load. By reducing the discharge air volume due to this action, it is possible to prevent a decrease in the energy consumption rate and to perform energy-saving operation.

[Problems to be Solved by the Invention] However, the temperature at the measurement point downstream of the confluence of the He gas G fed from the low-temperature side expander and the return gas G2 from the cryogenic environment section is extremely low. The change occurs with a slight delay after the heat load fluctuation occurs in the low-temperature environment, and with the above control method, if the heat load changes suddenly in the cryogenic environment, there will be a delay in control. Moreover, in order to maintain the cold state stably despite heat load fluctuations in the cryogenic environment section, simply controlling the throughput of the expander is insufficient; If the amount of cold supplied from the JT valve to the cryogenic environment is insufficient, the cooling state of the cryogenic environment will become unstable, and conversely, if the amount of cold supplied from the JT valve to the cryogenic environment is too large, there will be excessive cooling and the purpose of energy saving will not be achieved. .

Under such circumstances, even if the heat load in the cryogenic environment section suddenly changes, the present invention can quickly and appropriately control the amount of cold generated by the refrigeration system in accordance with the sudden change. The purpose is to provide an operation control method that can stably maintain the cold in the environment.

[Means for Solving the Problems] The configuration of the operation control method of the present invention that achieves the above objects is as follows: 1. For example, as shown in FIG. 4, cooling obtained by isentropic expansion of helium gas is In a method for controlling the operation of a helium liquefaction/refrigeration system in which helium gas at room temperature and high pressure is precooled in stages by a heat exchange action and then liquefied by passing it through a Joule-Thomson valve, a thermal load fluctuation detector is installed in the cryogenic environment section. In addition, for helium liquefaction, a temperature measuring device is installed downstream of the confluence of the discharge gas of the expander installed in the high-pressure helium gas supply circuit in the refrigeration equipment and the return gas from the cryogenic environment section, and the above-mentioned thermal load fluctuation detection is performed. In addition to calculating and controlling the necessary cold generation amount from the expander based on the heat load fluctuation of the cryogenic environment section determined by the The gist of this method is to calculate the refrigerant flow rate necessary for stabilizing the cold in the cryogenic environment based on load fluctuations and adjust the opening degree of the Joule-Thompson valve.

[Function] As will be made clear in the examples below, 1. Basic cold f#mal! of the present invention. The structure is similar to the technology shown in the tfSJ diagram, but in the present invention, as in the example shown in Fig. 4, the heat load from the cryogenic environment part changes due to the influence of heat load fluctuation in the cryogenic environment part. The amount of cold generation (discharge gas fI) from the expander installed in the high-pressure He gas supply circuit changes according to the temperature change of the return gas.
t), but as a woody control element,
A heat load fluctuation detector installed in the cryogenic environment section (e.g.
Directly detects heat load fluctuations due to liquid level, gas pressure, etc.
Based on this heat load variation, the required amount of cold generation from the Expansion 4Ii machine is calculated and controlled. Furthermore, the amount of refrigeration consumed in the cryogenic environment section is calculated based on the detected heat load fluctuations, and the amount of refrigerant supplied necessary to stabilize the cold state in the cryogenic environment section is determined, and the JT valve is automatically controlled appropriately. It is something to do.

That is, in the present invention, the heat load fluctuation in the cryogenic environment section is directly detected to control the cooling efficiency of the cold generation device of the He liquefaction building refrigeration system, and the amount of cold supply to the cryogenic environment section is controlled. Compared to the method shown in FIG. 4, the response to heat load fluctuations is extremely fast, and even if there is a sudden heat load fluctuation, there will be no delay on the He liquefaction φ refrigeration equipment side. The amount of refrigeration consumed in the cryogenic environment section is immediately calculated based on the above fluctuations in heat load, and the opening of the JT valve is adjusted so that an amount of refrigerant that can stably maintain the cooling capacity is supplied to the cryogenic environment section. Since the system is configured to automatically control the temperature, there is no possibility that the cooling capacity of the cryogenic environment section will decrease, resulting in a decrease in cooling efficiency, or that there will be no loss due to excessive cooling.

Also in the present invention, the I provided in the high pressure He gas supply circuit
A temperature measuring device is installed downstream of the confluence of the discharged gas of the Ii machine and the return gas from the cryogenic environment section, and the temperature measurement results are used as a control element for the throughput in the expander. In view of the fact that if the result is used as the main control element, the response to heat load fluctuations will be delayed as described above, in the present invention, the temperature measurement results are used to determine whether the required cold generation amount control value calculated from the heat load fluctuations is appropriate. This is used as a confirmation element to check whether the required cold generation amount control value is corrected or not, so that the control can be performed more accurately.

Thus, as the heat load changes in the cryogenic environment, H
It has become possible to control the operation of the e-liquefied fist refrigeration system extremely quickly and accurately.

Embodiment C] FIG. 1 is a schematic flow diagram showing an embodiment of the present invention, and the basic configuration is the same as the example in FIG. 4, so the same parts are given the same reference numerals. 6 In this example as well, the He gas purified by the purifier 4 after being pressurized by the compressor Ja3 is transferred to the run L.
2 to the liquefaction/refrigeration equipment main body 2, and is gradually cooled while passing through heat exchangers 5a to 5e sequentially along the high-pressure side path, and is partially liquefied by adiabatic expansion at the JT valve 6, and becomes extremely low temperature. It is supplied to the environment department 10. In the cryogenic environment section 1O, part of the liquefied He is vaporized under the cold load caused by, for example, a cryogenic fatigue test, and this low-pressure He gas flows again in the opposite direction through the heat exchangers 5a to 5e of the apparatus main body 2. After cooling the He gas flowing through the high-pressure side path of the counterflow, it returns to the compressor 3 from the line L as He gas at normal temperature and normal pressure. Here, in order to compensate for the lack of cooling in the device main body 2, a part of the He gas in the high pressure side path is bypassed to expander 7a.
, 7b to the low pressure side path, and in order to prevent the pressure drop of He gas in the high pressure side path,
The discharge pressure of the compressor 3 is detected by the pressure detection point 16, and the discharge amount of the compressor can be adjusted by the pressure controller 14 so as to keep this pressure constant, as shown in Fig. 4. This is the same as the conventional example.

In such a He liquefaction φ freezing device, the cryogenic environment section 10
When the heat load of I may invite you. Therefore, in the present invention, as shown in the figure, a liquid level gauge 17 is attached to the cryogenic environment section 10 and connected to a liquid level indicating regulator 18, and fluctuations in the liquid level that occur due to heat load fluctuations in the cryogenic environment section 10 are provided. Detect immediately.

Then, in this part, the return gas G2 commensurate with the liquid level fluctuation and the calorific value fluctuation of the gas at 15 points are estimated, the processing amount (discharged gas amount) of the expander 7b is calculated accordingly, and the signal is sent to the calculator 19. The processing unit 19 issues a command to increase or decrease the processing amount to the expander 7b.

In the present invention, as long as the above-mentioned (1) estimation of heat load fluctuation by liquid level detection, and (2) increase/decrease calculation and command of the expander 7b treatment shop according to the liquid level fluctuation are performed properly, the above-mentioned configuration alone is sufficient. Although the temperature inside the apparatus main body 2 is properly controlled, in this example, in order to more accurately control the throughput of the expander 7b, the following correction operation is also used. That is, the temperature measuring device 15 is disposed downstream of the confluence of the return gas G2 from the cryogenic environment section 1O and the discharge gas G from the expansion a7b, and the temperature measurement device 15 is installed downstream of the confluence of the return gas G2 from the cryogenic environment part 1O and the discharge gas G from the expansion a7b, and the temperature measurement device 15 is installed at this point to mix G and G2. Measure gas temperature. Then, in order to keep the mixed gas temperature extremely constant, the temperature control controller 13 calculates the throughput of the expander 7b and sends it to the computing unit 19. The calculation value sent from the liquid level control controller 18 is compared with the calculated value sent from the liquid level control controller 18, and the optimal throughput in the expander 7b is determined and instructed to the expander 7b. That is, in the present invention,
The control result of the expander 7b throughput calculated and instructed by the liquid level controller 18 and the calculator 15 is confirmed by the temperature measurement point 15 and the temperature controller 13, and then fed back to the calculator 19 to correct the control value. By doing so, control accuracy can be significantly improved. Moreover, expander 7b
The instructions for the required processing amount in the cryogenic environment section 10 are immediately issued via the calculator 19 after the heat load fluctuations in the cryogenic environment section 10 are directly detected by the liquid level gauge 17 and the liquid level control controller 18. Even if there is a problem, there is no fear that there will be a delay in control.

By the way, if the opening degree of the JTTe3 in the device main body 2 is fixed, even if the He liquid level fluctuates due to heat load fluctuations in the cryogenic environment section 10, the function to adjust it will not be activated, and the He
The liquid level may drop and the cooling capacity may be insufficient, or the liquefaction/refrigeration system #! The No. 12 side is in an over-operating state and the He liquid level rises excessively. Therefore, in the present invention, such He
To maintain constant cooling capacity by minimizing fluctuations in liquid level.

Based on the liquid level fluctuation value detected by the liquid level gauge 17, the amount of liquid He to be replenished into the cryogenic environment section 10 is calculated, and a signal for controlling the opening degree of the JTTe3 is transmitted from the liquid level controller 18. As a result, the cryogenic environment section 10 is replenished with liquid He in an amount corresponding to the fluctuation of the He liquid level.
The cooling capacity of the cryogenic environment section 10 can be kept as constant as possible.

FIG. 2 is a flow diagram showing another embodiment of the present invention, and shows an example of application to a recondensing He refrigerator. In this example, the refrigerant He is compressor 3 - heat exchangers 5a to 5e
- recondenser 20 in cryogenic environment lO - heat exchanger 5
A closed circuit is formed between a to 5e, and JTTe3He is liquefied and sent to the condenser 20 (P), where the latent heat of vaporization of He is used to absorb the heat load of the object to be cooled in the cryogenic environment lO. The cryogenic environment section IO is maintained at a cryogenic temperature.

In this case, the cryogenic environment section 10 constituting the freezing room has a sealed structure, and if there is a change in heat load within the cryogenic environment section 10, it will immediately appear as a pressure fluctuation inside the opening section 10. come. Therefore, in the present invention, a pressure detector 21 is attached to the cryogenic environment section 10, and the pressure fluctuation is constantly detected and inputted to the computer 22.

Then, the computer 22 estimates the return gas G2 commensurate with the gas pressure (thermal load) fluctuation in the cryogenic environment section 10 and the calorific value fluctuation of the gas at 15 points, and the expander 7
The processing amount of b (discharged gas sewing) is calculated and the signal thereof is sent to the computing unit 19, and the computing unit 19 issues a command to increase or decrease the processing amount to the expander 7b.

This command is immediately calculated and transmitted using the pressure fluctuations caused by the heat load fluctuations in the cryogenic environment section 10 as input data, so as in the example of FIG.
There is no fear that there will be a time delay in controlling the throughput of
However, in this example as well, the estimation of the heat load fluctuation and the expansion machine 7
b In order to more accurately calculate and control the required processing amount, correction is performed based on the actually measured gas temperatures at 15 points, as in the example of FIG.

That is, the temperature measuring device 15 is installed downstream of the confluence of the return gas G2 from the recondenser 20 and the discharge gas G from the expander 7b.
, and in this part G.

and G2, and the temperature control controller 13 calculates the required throughput of the expansion a7b and sends it to the calculator 19 so that the mixed gas temperature can be kept extremely constant. The calculation unit 19 compares and calculates the calculated value sent from the warm melon control controller 13 and the calculated value sent from the computer 22, determines the optimal discharge gas amount in the expander 7b, and sends the calculated value to the expander 7b. It gives instructions.

That is, in this example as well, the control result of the expander 7b processing performance calculated by the computer 22 based on the pressure fluctuation from the pressure detector 21 is fed back to the calculator 19 after being confirmed by the temperature measuring point 15 and the temperature control controller. Since the control value is corrected based on the value, highly accurate control is possible.

Furthermore, with only the configuration described in "-", it is not possible to maintain the inside of the circulation section 10 in a stable cold state when a sudden change in heat load occurs in the cryogenic environment section 10, resulting in insufficient cooling or excessive cooling. obtain. Therefore, in this example as well, the amount of liquid He fed to the recondenser 20 is automatically adjusted based on the pressure fluctuation detected by the pressure detector 21, thereby increasing the cooling capacity of the cryogenic environment section IO. The system is designed to immediately return to the state before the load change. That is, the flow rate of the refrigerant supplied to the recondenser 'Jh20 is measured at the flow rate measurement point 24, and is transmitted from the flow rate controller 23 to the JTjf6 so that it becomes a predetermined amount; however, in the present invention, this flow rate measurement value is computer 2
2, and when there is a change in heat load in the cryogenic environment section 1O, an amount of refrigerant commensurate with the change is transferred to the recondenser 2.
An opening adjustment signal is sent from the computer 22 to the JT valve 6 via the flow control controller 23 so that the flow rate reaches zero. As a result, the cold state in the cryogenic environment IO immediately returns to the state before the heat load change, and a stable cryogenic state is maintained.

In the present invention, when the discharge amount of the compressor 3 is constant, even if the processing amount of expansion@7b is changed according to the heat load, the required power of the He liquefaction refrigeration system does not change. If it decreases, there will be excessive cooling and the energy consumption rate will decrease. Therefore, in order to avoid such waste, as shown in Fig. 1, the discharge pressure of the compressor 3 is detected at the pressure detection point 16, and the pressure control controller 14 is used to keep this pressure constant. compression! It is preferable to have a configuration in which the discharge amount of &3 can be adjusted. By doing so, even if the heat load decreases, there is no fear that the main body of the device will be in an over-operating state, and energy-saving operation becomes possible.

The present invention is roughly configured as described above, but its most important feature is that heat load fluctuations in the cryogenic environment are directly detected by liquid level fluctuations, pressure fluctuations, etc., and based on the measured values, (a)
(b) Calculating the required amount of cold generation from the expander in the He liquefaction Φ refrigeration equipment body and controlling the expander;
Based on the measured value, the flow rate of chilled colander necessary for stabilizing the cold in the cryogenic environment section is calculated and the opening degree of the JT valve is adjusted. For example, FIG. 1.2 shows an example in which five heat exchangers are combined, but the number of heat exchangers is of course not limited to that shown and can be increased or decreased as appropriate. Further, although the figure shows an example in which only the discharge amount of the low-temperature section side expander 7b is controlled, the discharge rate of the high-temperature section side expander 7a can also be controlled in the same manner. Furthermore, although the illustrated examples all show an example in which one cryogenic environment section is connected to one He liquefaction refrigerator, it is also possible to connect multiple cryogenic environment sections in parallel to one He liquefaction φ refrigerator. Of course, ClTm can also be applied to refrigeration systems (multi-user systems) that are connected to other systems. In particular, the present invention has the advantage of being able to respond quickly to sudden changes in heat load, and also maintain a cryogenic environment in a stable cold state despite sudden changes in heat load. For example, it can be said that its features can be most effectively exhibited when applied to the multi-user system, etc., where the heat load is likely to change suddenly due to a change in the operating number of the cryogenic environment section.

[Effects of the Invention] The present invention is configured as described above, and its effects can be summarized as follows.

(1) Since this method directly detects and controls heat load fluctuations in the cryogenic environment, the response is extremely fast and there is no delay in control.

(2) Since this method performs feedback control while correcting the value calculated from the 8 load fluctuation values with the value obtained from the actual measured value after control, there is no risk of erroneous control and the control accuracy is high.

(3) In the conventional example, fluctuations in the cooling capacity of the cryogenic environment section caused by heat load fluctuations were not strictly controlled, but in the present invention, the cooling capacity of the cryogenic environment section is simultaneously adjusted to the state before the heat load change. It can be reinstated. Therefore, maintaining the cooling capacity stably despite fluctuations in heat load is the key to circulation, and there are no problems such as insufficient cooling or excessive cooling.

[Brief explanation of the drawing]

FIG. 1.2 is a flow diagram illustrating an embodiment of the invention. FIG. 3.4 is a flow diagram for explaining a known He liquefaction/refrigeration system and its operation control method. 2... Refrigeration equipment main body 3... Compressors 5d to 5e
...Heat exchanger 6...JT valve 7a...High temperature side expansion machine 7b...Low temperature side expansion machine IO...Cryogenic environment section (user) I3...Temperature control controller 14... Pressure control controller 15...Temperature measurement point 1B...Pressure detection point 1
7...Liquid level gauge 18...Liquid level control controller 18...Arithmetic unit 20...Recondenser 21
...Pressure detector 22...Computer 23
...Flow control controller Applicant: Kobe Steel, Ltd. Figure 1 L+ Figure 2 1゜Figure 3

Claims (2)

[Claims] (1) Operation of a helium liquefaction/refrigeration system that precools helium gas at room temperature and high pressure in stages by a heat exchange action that utilizes the cold obtained by isentropic expansion of helium gas, and then liquefies it by passing it through a Joule-Thomson valve. In the control method, a heat load fluctuation detector is installed in the cryogenic environment section, and a heat load fluctuation detector is installed in the helium liquefaction/refrigeration equipment at the confluence point of the discharge gas of the expander installed in the high-pressure helium gas supply circuit and the return gas from the cryogenic environment section. A temperature measuring device is provided on the downstream side, and the necessary amount of cold generation from the expander is calculated and controlled based on the heat load fluctuation of the cryogenic environment section determined by the heat load fluctuation detector, and the control is performed. In addition to making corrections based on the temperature measurement results from the temperature measuring device, the opening degree of the Joule-Thomson valve is adjusted by calculating the refrigerant flow rate necessary for stabilizing the cold in the cryogenic environment based on the heat load fluctuations. A method for controlling the operation of helium liquefaction/refrigeration equipment. (2) The operation control method according to claim 1, wherein the pressure on the discharge side of the compressor that supplies helium gas at room temperature and high pressure is detected and the compressor is controlled so that the detected value is constant.