JPS63286670A - Small-sized he 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] (Industrial application field) The present invention relates to a small-sized He liquefaction refrigeration device.

(Prior technology) Currently, cryogenic equipment including small superconducting magnets is cooled by pre-cooling with liquid nitrogen (hereinafter referred to as LN2), then discharging the LN2 and using H
After replacing with e gas, liquid helium (hereinafter referred to as LH) is added.
This is done by pre-cooling in e) and storing LHe. After that, long-term cooling is performed by replenishing LHe, cooling the shield plate with a He refrigerator, and recondensing the evaporated He gas.

(Problems to be Solved by the Invention) To provide a closed-cycle small He liquefaction refrigeration system that can perform precooling, liquefaction, long-term cooling, and gas recovery for cooling small superconducting magnets, etc. without using external LN or LHe. This is an attempt to save labor and improve operability by automating the process so that even an amateur can easily operate it.

(Solution Means by the Invention) A He liquefying refrigerator and a He liquefier for supplying He to the refrigerator.
A compressor unit connected to the container is connected in a closed circuit, and the He liquefaction refrigerator has a heat exchanger, a J-T valve, and piping for freely expanding high-pressure He, and has a switchable He
J-7 circuit with liquefaction circuit and condenser circuit, and H for condensation
A circuit for supplying He, a Y/cold piece refrigerator for pre-cooling the He flowing through both circuits, and a liquid He container for storing the object to be cooled. In order to obtain operation control signals, a thermometer and liquid He
A liquid level gauge was installed.

(Example) The He liquefaction refrigeration apparatus is composed of a compressor unit B connected to the He liquefaction refrigerator A by conduits 34, 35, and 36. One device can pre-cool the object to be cooled, measure liquid He, re-condense evaporated He gas, and
Gas condensation and liquefaction and recovery of liquefied He can be performed automatically.

He liquid liquefaction refrigerator The inside of the circle includes a pre-cooling refrigerator 21 equipped with a heat load flange 10.11, a J-T valve 15 outside a condensing circuit consisting of a J-T valve 15, a three-way valve 16, and a condenser 27. A direct liquefaction circuit consisting of a three-way valve 16, a liquid He container 18, and a low temperature valve 28 is provided.

In addition, in order to supply He gas for condensation and liquefaction, a filter 19, a condensed He supply valve 24, a pressure reducing valve 25, and a check valve 2 are provided.
6 and a condensed He supply system 23.

Inside the compressor unit B is a storage tank 6, which is connected to a He container 8.

(Action and automatic control) In the He gas system before operation, high-purity He is placed on the high-pressure side and low-pressure side.
When the operation switch of the 6 control circuit (not shown) is turned on to set the cooling mode, the condensed He supply valve 24 closes and the three-way valve 16 c
At the same time as the -b direction, the low temperature valve 28, and the three-way valve 16a open in the b-a direction and perform switching operations, the -membrane compressor 1, two-stage compressor 2, and precooling refrigerator 21 are started.

He compressed by the single-stage compressor 1 in the compressor unit B is further compressed by the two-stage compressor 2 to 20 kg/aJG, passes through the oil separator 3 and adsorber 4, becomes clean He, and is sent to the pipe. 34 to the He liquid liquefaction refrigerator.

The He that has flowed into the liquefaction refrigerator A is transferred to the precooling refrigerator 21 and the J
- Divided into 7 circuits. The He that has flowed into the pre-cooling refrigerator 21 generates a low temperature, cools the first heat load flange 10 and the second heat load flange 11, and is sucked into the two-stage compressor 2 in the compressor unit B via the pipe line 35. Ru. On the other hand, H of the J-T circuit
e passes through the filter 19, the single-stage heat exchanger 12, is cooled by the single-stage heat load flange 1o, passes through the two-stage heat exchanger 13, is further cooled by the second-stage heat load flange 11, and is cooled by the three-stage heat exchanger 14, After leaving J-T valve 15, 0.21cg/c
It expands to below JG and directly cools the superconducting coil 17 and liquid helium container 18.

This low pressure He is supplied to the low temperature valve 28, the precooling circuit 31, the three-way valve 16
a. Passes through the single-stage heat exchanger 12, exchanges heat with the high-pressure inflow He, raises the temperature, and connects the pipe 3 to the single-stage compressor 1 of the compressor unit B.
6 and then inhaled. In this state, when the thermometer 29 of the liquid He container 18 reaches 25 K, the three-way valve 16a switches to close the precooling circuit 31, and the three-way valve 16a opens in the ca direction. Therefore, the two-stage heat exchanger 13 and the three-stage heat exchanger 14
The high-pressure He flowing into the J-T valve 15 is further cooled by heat exchange at
7. Further cool the liquid He container 18. Eventually, a portion of the He that exits in the c-b direction of the three-way valve 16 is liquefied, and eventually liquid He accumulates in the liquid He container 18 and the liquid level rises.

When the liquid He in the liquid He container 18 reaches a certain height,
The liquid level gauge 30 senses it, and the three-way valve 16 switches and operates c-b.
direction is closed, Q-a direction is open, and cryogenic valve 28 is closed.

Thus, the He refrigerant (mixture of gas and mist) generated by the Joule-Thomson effect in the J-T valve 15 is transferred to the condenser 2.
Flows within 7. As a result, H vaporized in the liquid He container 18
e is recondensed into a liquid in the condenser 27, and the liquid He in the liquid He container 18 is kept constant.

Meanwhile, in this state, the condensed He supply valve 24 is opened, and the pressure reducing valve 25 is opened.
to adjust the pressure in the liquid He container 18 to the condenser 27.
When He is supplied through the condensed He supply system 23 such that the pressure is higher than the pressure of Then, it condenses in the condenser 27 and becomes liquid He, which accumulates.

He necessary for the above cooling operation is supplied from a He container 8 connected to the compressor unit A through a conduit 37.

To stop the cooling operation, turn on the stop switch in the control circuit to enter the recovery mode, the precooling refrigerator 21 will stop, the low temperature valve 28 will open, the compressor unit B will continue the recovery operation, and the liquid He The vaporized He in the container 18 is transferred to the He container 8.
Collect to. After that, when the thermometer 29 reaches normal temperature, the compressor unit B stops and returns to the state before operation. After that, the above operation is repeated.

The pressure control function of the compressor unit B is such that when He at the adsorber 4 exceeds 20 kg/cdG, the primary pressure regulator 5
is activated to hold He in the storage tank 6, - When the suction pressure of the membrane compressor 1 decreases, the secondary pressure regulator 7 is activated and the I-I e in the storage tank 6 and the He container 8 is reduced.
is supplied. Also, when the precooling refrigerator 21 stops,
Since the differential pressure regulator 9 operates, the high pressure, medium pressure,
Each pressure of low pressure is automatically adjusted.

Next, a method of controlling the apparatus shown in FIG. 1 will be explained with reference to the block diagram shown in FIG.

Regarding operation; 1) When the operation switch on the control panel is turned on, the membrane compressor 1, two-stage compressor 2, and refrigerator motor 32 start, and at the same time, the three-way valve 16 turns c-b and the three-way valve 16a turns b- Open in direction a. Also, the supply valve 33 is opened.

Then, the He gas from the compressor unit B flows into the precooling refrigerator 21 of the He liquefaction refrigerator A and the J-T circuit, and the precooling operation of the liquid He container 18 is started. At this time, both J-T valves 15 and 15a are in position.

Note that the J-T valve 15 is always open and used as a fixed valve.

2) When the thermometer 29 indicates the following at 25, the J-T valve 15a
is closed, reducing the flow rate of the J-T valve, and the three-way valve 16a is closed.
By opening in the -a direction, the inside of the liquid He container 18 is further cooled.

3) When the thermometer 29 becomes 5 or less, the liquid level gauge 30 is turned on and operates 1. When the liquid level gauge 30 shows 100%, L
Since He liquefaction is completed, the three-way valve 16 is opened in the c-a direction, and the low temperature valve 28 is closed. ...recondenses into a liquefied state.

4) After this, liquid H is removed by power lead or other operations.
e When LHe in the container 18 is evaporated and released.

The liquid level of LHe decreases. When the liquid level gauge 30 indicates 80% or less, the condensed He supply valve 24 opens and He is supplied, condensed and liquefied, and the LHe liquid level increases. Level gauge 30 is 100% again
When , the condensed He supply valve 24 closes. The above operations are repeated.

5) When the cooling operation is completed, the LHe in the liquid He container 18 is
is collected and prepared for the first operation.

Regarding recovery; 6) When the recovery switch is turned on for recovery operation, the refrigerator motor 32 stops, the low temperature valve 28 opens,
Supply valve 33 is closed. LHe is vaporized and recovered as He gas into the storage tank 6 or He container 8 of the compressor unit B.

7) When the thermometer 29 reaches 5 or higher, the power to the liquid level gauge 36 is turned off to protect the liquid level gauge 30. After that, when the thermometer 29 shows 265 or higher, the first and second stage compressors 1 and 2
stops at the same time and ends the collection operation (in the above explanation,
Although the set temperature of the thermometer 29 was set to 265, 25, and 5, it is also possible to change the setting to 265 and 25. The same applies to the settings of the liquid level gauge 30).

(Effects) One device can pre-cool the object to be cooled, store LHe, and evaporate He.
The recondensation of gas, the condensation and liquefaction of He gas, and the recovery of liquefied He can now be performed automatically. This eliminates the need for amateurs to operate a small superconducting magnet, which requires the conventional operation of first introducing LN2 to cool it, then exhausting the remaining N2 gas through He gas, and then introducing LHe. However, it is now easier to operate.

[Brief explanation of the drawing]

FIG. 1 is a piping diagram of a small-sized He liquefaction refrigeration system according to the present invention. FIG. 2 is also an automatic control block diagram of the device. In the figure: 1 - membrane compressor 2 two-stage compressor 3 oil separator 4 adsorber 5-order pressure regulator 6 storage tank 7 secondary pressure regulator 8 He container 9 differential pressure regulator 10 - extra-membrane load flange 11 Two-stage heat load flange 12 - Extra-membrane exchanger 13 Two-stage heat exchanger 14
Three-stage heat exchanger 15 J-T valve (1) 15a (
Gas pressure driven) J-T valve (2) 16 (Gas pressure driven) Three-way valve (1) 16a (Gas pressure driven) Three-way valve (2) 17 Superconducting coil 18 Liquid He container 19
Filter 20 Shield plate 21 Pre-cooling refrigerator 22 Vacuum insulation container 23 Condensed He supply system 24 (gas pressure driven) Condensed He supply valve 25 Pressure reducing valve 26 Check valve 27 Condenser 28 (gas pressure driven) Low temperature valve 29 Thermometer 30 Liquid level gauge 31 Pre-cooling circuit 32 Freezer motor 33 (gas pressure driven) supply valves 34, 35, 36, 37 Pipe lines and above

Claims (1)

[Claims] A He liquefaction refrigerator (A) and a compressor unit (B) connected to a He container for supplying He to the refrigerator (A) are connected in a closed circuit, and the He liquefaction refrigerator (A) is operated under high pressure. He
A J-T circuit that has a heat exchanger for free expansion, a J-T valve and piping, and is equipped with a switchable He liquefaction circuit and a condenser circuit, and a circuit that supplies He for condensation. A pre-cooling refrigerator is provided to pre-cool the He flowing through both circuits, and a liquid He container is provided to store the object to be cooled. A small-sized He liquefaction refrigeration device characterized by being provided with a liquid He liquid level gauge.