JP2694377B2 - Helium gas purifier - Google Patents

Description

TECHNICAL FIELD The present invention relates to a helium gas refining apparatus, and more particularly to a helium gas refining apparatus with improved refining performance and energy saving.

[Prior Art] Conventionally, as a helium gas refining device for refining helium gas containing impurities such as air components by use, a regenerator type helium refrigerator such as Gifford
McMahon cycle refrigerator (hereinafter referred to as "GM refrigerator")
A low-temperature device configured to adsorb impurities at a low temperature while using the difference in liquefaction temperature between helium gas and a gas component or the like that is an impurity is used. For example, a gas-liquid separator and an adsorber are installed on the heat load flange of a cold storage helium refrigerator to cool it to a refining temperature (77K or less) and to exchange high-pressure helium gas (purified gas) containing impurities with a heat exchanger. There is one configured to purify the helium gas by flowing it through the reactor (JP-A-64-6656).
issue).

In the low-temperature device having such a configuration, the GM refrigerator is operated at a commercial frequency, the thermometer provided in the cooled portion and the electric heater are linked by PID operation (proportional integral differential operation), and the flow rate of the gas to be purified or The simplest and widely known method is to control the temperature according to the purity.

However, this conventional method is
By operating the GM refrigerator, the cooled part is once cooled to a certain low temperature, and the temperature of the cooled part is controlled by an electric heater according to the flow rate or the purity of the gas to be purified.
There is a problem of wasting power consumption.

[Problems to be Solved by the Invention] The present invention has been made in view of the above problems, and enables purification with good efficiency regardless of the flow rate or purity of the gas to be purified, improving the purification performance and saving energy. It is an object of the present invention to provide a helium gas refining device that simultaneously achieves gasification.

[Means for Solving the Problems] That is, the present invention provides a vacuum heat insulating container, a cold storage helium refrigerator provided in the vacuum heat insulating container, a first stage heat exchanger for introducing and extracting a gas to be purified, and the above cold storage. Gas-liquid separation filter attached to the first stage heat load flange of the system helium refrigerator, and the first stage adsorber, and the second stage adsorber attached to the second stage heat load flange of the regenerative helium refrigerator. A helium gas purification device having a second stage heat exchanger provided between the first stage heat exchanger and the first stage heat exchanger, and detecting the temperatures of the gas-liquid separation filter and the first stage heat exchanger. The helium gas refining device is characterized in that the operating frequency of the cold storage helium refrigerator is controlled by using an inverter or the like based on the temperature detection signal.

[Operation] In the helium gas refining apparatus according to the present invention, the operating frequency is controlled by PID control by the inverter or the like based on the temperature detection of the cooling unit by the regenerator helium refrigerator, so that the gas to be purified (helium gas) Regardless of the flow rate and the purity of, the cooling temperature of the gas-liquid separation filter and the adsorber was controlled to the optimum temperature, for example, 77K to 65K, and it was decided to obtain the required refrigeration capacity with the required frequency power.
It can be operated with the minimum required power consumption, and energy can be saved.

[Embodiment] Next, a helium gas purification apparatus 1 according to an embodiment of the present invention will be described with reference to FIG.

FIG. 1 is a schematic sectional view of the helium gas refining apparatus 1, which is a vacuum heat insulation container 2
And a GM refrigerator 3, a first stage heat exchanger 4, a gas-liquid separation filter 5, a first stage adsorber 6, a second stage heat exchanger 7, and a second stage adsorber 8 provided in the vacuum heat insulating container 2. Have.

The first stage heat exchanger 4 has a gas to be purified (helium gas).
A purified gas inlet valve 9 for introduction and a pressure adjusting valve 10 for discharge are attached.

The gas-liquid separation filter 5 is attached to the first stage heat load flange 3A of the GM refrigerator 3 and is connected to the first stage heat exchanger 4 by piping. Gas-liquid separation filter 5
A liquid discharge valve 11 is attached to and an upper filter 5A capable of removing solidified impurities is incorporated. The gas-liquid separation filter 5 is connected to the first stage adsorber 6.

The first stage adsorber 6 is also attached to the first stage heat load flange 3A of the GM refrigerator 3 and is connected to the second stage heat exchanger 7.

The second-stage heat exchanger 7 is connected to the second-stage adsorber 8 so as to form a reciprocating flow path between the second-stage heat exchanger 7 and the first-stage heat exchanger 4 on the downstream side thereof. Are connected.

The second stage adsorber 8 is attached to the second stage heat load flange 3B of the GM refrigerator 3. An electric heater 12 is provided in each of the gas-liquid separation filter 5, the first stage adsorber 6 and the second stage adsorber 8.

Each of the first-stage heat exchanger 4, the gas-liquid separation filter 5, the first-stage adsorber 6, the second-stage heat exchanger 7 and the second-stage adsorber 8 are connected by a pipe as shown in the figure to form a purification circuit, Helium gas shall be circulated.

A seal-off valve 13 is attached to the vacuum heat insulating container 2 so that the inside of the vacuum heat insulating container 2 can be evacuated to vacuum, and each member in the vacuum heat insulating container 2 is wrapped with a multi-layer heat insulating material 14.

The GM refrigerator 3 is driven by the compressor unit 15. This compressor unit 15 includes a control unit 16 and a compressor 17 for a refrigerant for the GM refrigerator 3 such as helium gas.
And a power supply section 18 of this compressor 17.

The compressor unit 15 includes a control circuit 19 and a PID controller 20.
And an inverter (frequency converter) 21.

The PID controller 20 is connected to a thermometer 22 provided on the first stage heat load flange 3A.

The thermometer 22 can measure the temperatures of the gas-liquid separation filter 5 and the first stage adsorber 6.

The operation of the helium gas refining device 1 having such a configuration will be described below.

First, before the refining operation, the inside of the vacuum insulation container 2 is made to have a predetermined degree of vacuum by exhausting air from the seal-off valve 13.
Further, helium gas replacement in the purification circuit starting from the first stage heat exchanger 4 is sufficiently performed at room temperature. Then, the purified helium gas is sealed in the purification circuit at a predetermined pressure, and the GM with the gas to be purified inlet valve 9 and the pressure adjusting valve 10 closed.
By starting the refrigerator 3, the first stage heat load flange
Start cooling of 3A and the second stage heat load flange 3B.

When the gas-liquid separation filter 5 and the first-stage adsorber 6 are cooled to a temperature of 65K by this cooling, the gas to be purified inlet valve 9 is opened, and helium gas containing impurities is introduced. The pressure of the pressure control valve 10 is set slightly higher than the pressure of the enclosed gas (about 10 atm).

The inflowing helium gas passes through the high temperature side of the first-stage heat exchanger 4 and exchanges heat with the low temperature side thereof, so that some impurities such as moisture, nitrogen gas, oxygen gas, carbon monoxide or carbon dioxide are liquefied. Alternatively, it enters the gas-liquid separation filter 5 in the state of being solidified and powdered.

The liquefied impurities containing a part of the powder separated in the gas-liquid separation filter 5 accumulate at the bottom thereof, and when a certain amount is accumulated, they are discharged from the liquid discharge valve 11 to the atmosphere side.

The helium gas from which the shallow powder has been separated and removed by the upper filter 5A of the gas-liquid separation filter 5 reaches the first stage adsorber 6 while still containing the saturated vapor pressure of impurities such as nitrogen gas or oxygen gas. .

In the first-stage adsorber 6, the saturated vapor pressure component of the impure gas is adsorbed and removed, and the helium gas passes through the high-temperature side of the second-stage heat exchanger 7 and exchanges heat with the low-temperature side of the second-stage heat exchanger 7, so that the temperature is about 18K. To be cooled.

Hydrogen gas other than helium gas, neon gas, etc. are adsorbed and removed from the helium gas flowing into the second-stage adsorber 8 to obtain highly purified purified helium gas. Second stage adsorber 8
The high-purity helium gas that has exited is heated through the low temperature side of the second stage heat exchanger 7 and the low temperature side of the first stage heat exchanger 4, and can be taken out via the pressure control valve 10.

When the purification operation as described above causes the filter portion of the gas-liquid separation filter 5 to be clogged and the first-stage adsorber 6 or the second-stage adsorber 8 to break through, the GM refrigerator 3
Then, the gas to be purified inlet valve 9 and the pressure adjusting valve 10 are closed. Further, helium gas is discharged from the liquid discharge valve 11, and the temperatures of the gas-liquid separation filter 5, the first-stage adsorber 6 and the second-stage adsorber 8 are controlled by an electric heater.
The temperature in the thermometer 22 is raised by 12 to a normal temperature to discharge and regenerate the impurities in the refining circuit to prepare for the next refining operation.

Now, when the purity of the inflowing helium gas is 99% or less, the temperature of the gas-liquid separation filter 5 is operated in the range of 77K to 65K, and the helium gas flowing in through the first-stage heat exchanger 4 It is important that the impurities such as nitrogen gas and oxygen gas are liquefied and flow into the gas-liquid separation filter 5.

In addition, when the temperature of the gas-liquid separation filter 5 is operated at 65 K or less and impurities in the inflowing helium gas are solidified,
The gas-liquid separation filter 5 becomes clogged and purification becomes impossible.

Regarding the adsorbers such as the first-stage adsorber 6 and the second-stage adsorber 8, if the adsorption temperature is lowered to 77 K or less, not only impurities such as nitrogen gas and oxygen gas but also hydrogen gas adsorbing ability is increased. The lower the adsorption temperature of the second stage adsorber 8,
The purification capacity and the purity of the purified gas are also improved.

When the purity of helium gas is 99% or more, impurities such as nitrogen gas and oxygen gas are hardly purified even if the temperature of the gas-liquid separation filter 5 is operated in the range of 77K to 65K.
In this case, the temperature of the gas-liquid separation filter 5 is further lowered to improve the purification capacity and the purity of the purified gas.

Next, the control regarding the operation of the GM refrigerator 3 will be described below.

The inverter 21 provided in the power supply section 18 of the compressor 17 for operating the GM refrigerator 3 and the thermometer 22 provided on the first-stage heat load flange 3A of the GM refrigerator 3 are linked through the PID controller 20 to separate gas and liquid. The temperature of the filter 5 is PID controlled.

That is, the frequency range of the inverter 21 is set to match the power supply frequency rating of the compressor 17 (generally 60 Hz).
30 to 60 hertz.

When the flow rate of the helium gas flowing into the first-stage heat exchanger 4 increases, the efficiency of the first-stage heat exchanger 4 decreases, so GM
The heat input to the refrigerator 3 also increases. Further, if the purity of the helium gas is low, the cold heat liquefied by cooling the impurities is discharged through the liquid discharge valve 11, so that the GM refrigerator 3 has a large refrigeration burden.

In order to control the temperatures of the gas-liquid separation filter 5, the first stage adsorber 6 and the second stage adsorber 8 in response to changes in the refrigeration load due to changes in the flow rate or purity of the helium gas, first set the temperature for PID control. Set to 70K and room temperature (30
The operation of the GM refrigerator 3 is started from 0K).

At the beginning of operation, the temperature difference between the PID control set temperature and the gas-liquid separation filter 5 is large, so the GM refrigerator 3 is operated at maximum capacity (60 hertz) until the temperature of the gas-liquid separation filter 5 approaches 70K. It

When the temperature approaches 70K, the frequency of the power supply unit 18 is controlled by the PID controller 20 in response to the temperature detection signal from the thermometer 22, and the GM refrigerator 3 is operated at the frequency corresponding to the refrigerating capacity at 70K.

That is, as the flow rate of helium gas increases,
The temperature of gas-liquid separation filter 5 rises above 70K, but PID
By the control, the operating frequency of the GM refrigerator 3 is controlled in the increasing direction.

Further, if the flow rate decreases during the helium gas refining operation, the temperature of the gas-liquid separation filter 5 will drop below 70K, and the operating frequency of the GM refrigerator 3 will be controlled in the decreasing direction.

Thus, regardless of the flow rate or purity of the helium gas to be purified, the temperature of the cooling section such as the gas-liquid separation filter 5 and the adsorbers 6 and 8 can be controlled by the GM refrigerator 3 to improve the purification performance or operability. be able to.

Furthermore, even in areas where the commercial frequency is 50 Hertz, 60 Hertz operation is possible, and the refining processing capacity can be improved. Further, there is no problem such as disconnection as compared with the conventional control method of the electric heater.

[Effects of the Invention] As described above, according to the present invention, the operating frequency of the regenerative refrigerator is controlled by using an inverter or the like.
It is possible to reduce power consumption to the minimum necessary for refining operation, improve refining performance, and save energy.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a helium gas purification apparatus 1 according to an embodiment of the present invention. 1 …… Helium gas refining device 2 …… Vacuum insulation container 3 …… GM refrigerator 3A …… First stage heat load flange 3B …… Second stage heat load flange 4 …… First stage heat exchanger 5 …… Gas-liquid separation Filter 5A …… Upper filter 6 …… First stage adsorber 7 …… Second stage heat exchanger 8 …… Second stage adsorber 9 …… Refine gas (helium gas) inlet valve 10 …… Pressure control valve 11… Liquid discharge valve 12 Electric heater 13 Seal off valve 14 Multilayer insulation 15 Compressor unit 16 Control unit 17 Compressor 18 Power unit 19 Control circuit 20 PID controller 21 ... Inverter (frequency converter) 22 ... Thermometer

Claims (1)

(57) [Claims] 1. A vacuum heat insulating container, a regenerator helium refrigerator provided in the vacuum heat insulating container, a first stage heat exchanger for introducing and extracting a gas to be purified, and a first stage heat load for the regenerator helium refrigerator. A gas-liquid separation filter attached to the flange, and a first stage adsorber, a second stage heat load of the regenerator helium refrigerator, a second stage adsorber attached to the flange, the second stage adsorber and the first stage heat A helium gas refining device having a second stage heat exchanger provided between the exchanger, the temperature of the gas-liquid separation filter and the first stage adsorber is detected, and based on this temperature detection signal, A helium gas refining device characterized by controlling the operating frequency of a cold storage helium refrigerator.