JPS6050353A - Method of controlling auxiliary cold source of cryogenic liquefying refrigerator - 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] [Field of Application of the Invention] The present invention relates to a cryogenic liquefaction refrigeration system using an auxiliary cooling source such as liquid nitrogen, and is particularly suitable for a cryogenic liquefaction refrigeration system suitable for long-term continuous operation. This invention relates to a method for controlling an auxiliary cold source.

[Background of the invention]

In cryogenic liquefaction refrigeration equipment, the energy efficiency of the equipment is generally improved by using liquid nitrogen or the like as an auxiliary cooling source. Therefore, properly controlling the supply amount of the auxiliary cold source maintains the capacity of the device! It is also important to maintain optimum energy efficiency.

The helium liquefaction refrigeration system will be explained below as an example. FIG. 1 is a block diagram showing an example of a configuration for controlling an auxiliary cold source of a conventional helium liquefaction refrigeration system. In FIG. 1, 1 is a compressor unit, 2 is an intermediate pressure tank, 3a and 3b are pressure control valves, 5 is a high-pressure refrigerant gas introduction pipe, and 6
is a low-pressure refrigerant gas outlet pipe, 7 is a temperature controller, 88 to 8c
is a flow control valve, 9 is a cold box, 10 a to 10
e is a heat exchanger, 12a and 12b are expanders, and 14 is an object to be cooled.

Next, the operation of the conventional helium liquefaction refrigeration system configured as described above will be described. The high-pressure refrigerant gas compressed by the compressor unit 1 passes through the introduction pipe 5 to the cold box 9.
After being cooled by liquid nitrogen and low-pressure refrigerant gas in the first heat exchanger 10a, it branches into a liquefaction line and an expander line. The high-pressure refrigerant gas branched into the expander line undergoes the first expansion! After generating cold by performing adiabatic expansion work in ll 12 a, the third heat exchange!
Il! The temperature is further lowered by exchanging heat with the low-pressure refrigerant gas in the IOC, and the second expander 12b performs adiabatic expansion work again to generate refrigeration, which joins the low-pressure line. The high-pressure refrigerant gas branched into the liquefaction line exchanges heat with the low-pressure refrigerant gas in the second to fifth heat exchangers IO B to 10e', and is finally cooled to below the reversal temperature. By performing Tomgen expansion, a cryogenic refrigerant is generated and sent to the object 14 to be cooled. The cryogenic refrigerant that has absorbed the heat load in the object to be cooled 14 returns to the cold box 9, recovers the cold by exchanging heat in the heat exchangers 1 (LE to 10A), and then returns to the compressor unit 1.

On the other hand, the liquid nitrogen, which is an auxiliary cooling source, is controlled by a temperature controller 7. Flow control valve 8a
controlled by

In the conventional helium liquefaction refrigeration system configured as described above, when the temperature of the cooling water used in the compressor unit 1 changes, the temperature of the high-pressure refrigerant gas changes, and the temperature difference between the refrigerant gas output and log gas in the cold box 9 changes. Change. This means that the cooling loss in the cold box 9 due to the temperature difference in the output log gas changes, and the equipment capacity fluctuates.

The above relationship will be explained with reference to FIG. FIG. 2 is an example showing the device capacity using the inlet temperature and outlet iii of the cold box refrigerant gas as parameters. As shown in FIG. 2, it can be seen that in order to maintain the device capacity in response to the high-pressure refrigerant gas inlet temperature, it is necessary to change the low-pressure refrigerant outlet temperature.

As mentioned above, in conventional helium liquefaction refrigeration equipment, in order to maintain equipment capacity in response to changes in high-pressure refrigerant inlet gas temperature and to optimize the usage of liquid nitrogen, which is an auxiliary cooling source,
It was necessary to frequently adjust the suggested value of the temperature controller.

[Purpose of the invention]

An object of the present invention is to provide a method for appropriately and easily controlling the auxiliary cold source in an extremely low i liquefaction refrigeration system using liquid nitrogen or the like as the auxiliary cold source.

[Summary of the invention]

In a cryogenic liquefaction refrigeration system, the temperature of the cooling water used in the compressor unit inevitably fluctuates depending on the ambient conditions, such as night and day, winter and summer.

On the other hand, in order to maintain the heat balance of the cold box, it is necessary to maintain a constant temperature difference between the cold box and the refrigerant waste. The present invention is.

By using the i degree difference of the refrigerant gas as a control variable and manipulating the supply amount of the auxiliary cold source, the device capacity can be maintained and the amount of auxiliary cold source used can be properly controlled.

- [Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described with reference to FIG. In FIG. 3, in order to avoid duplication, the same parts as in FIG. 1 are given the same reference numerals and their explanations are omitted, and the parts that are different from FIG. 1 will be mainly described. Reference numeral 15 denotes an arithmetic unit for calculating a control set value for the low-pressure refrigerant gas temperature from the gas temperature of the high-pressure refrigerant gas introduction pipe 5. Other parts are the same as in FIG.

Next, the operation of the present invention having the above configuration will be explained. The temperature of the high-pressure refrigerant gas introduced from the compressor unit 1 fluctuates as the temperature of the cooling water in the compressor unit 1 fluctuates. Calculate the temperature setpoint,
Set in the controller 7 Based on the above set value, the controller 7 controls the supply amount of liquid nitrogen, which is an auxiliary cold source, by controlling the flow rate control valve 8a.
control by operating.

As described above, according to this embodiment, it is possible to appropriately maintain the heat balance of the cold box against fluctuations in the high-pressure refrigerant gas IIi degrees introduced into the cold box. It becomes possible to easily maintain the appropriate amount of energy used.

〔Effect of the invention〕

According to the present invention, it becomes easy to appropriately maintain the equipment capacity of the cryogenic liquefaction refrigeration equipment, the amount of auxiliary cold source used can be appropriately and easily controlled, and the energy efficiency of the equipment is improved. be.

[Brief explanation of the drawing]

Figure 1 shows the configuration of a conventional cryogenic liquefaction refrigeration system It.
FIG. 2 is a diagram showing an example of the characteristics of a cryogenic liquefaction refrigeration system, and FIG. 3 is a block diagram showing an embodiment of a cryogenic liquefaction refrigeration system embodying the present invention. l...Compressor unit, 5...Introduction pipe, 6...Lip outlet pipe, 7...Control spring, 8...Flow rate control Valve, 9...years old 1 figure 31 = 2 times a period refrigerant

Claims (1)

[Claims] 1. A compressor unit that compresses and circulates refrigerant gas, and liquid nitrogen or the like as an auxiliary cooling source, which generates extremely cold air by making some or all of the high-pressure refrigerant gas compressed by the compressor unit perform adiabatic expansion work. In a cryogenic liquefaction refrigeration system consisting of a cold box that generates low-temperature refrigerant, an auxiliary refrigeration system is used to maintain a constant temperature difference between the high-pressure refrigerant gas compressed by the compressor unit and the low-pressure refrigerant gas returned from the cold box. 1. A method for controlling an auxiliary cold source for a cryogenic liquefaction refrigeration system, the method comprising controlling the supply amount of the cold source.