JP3252261B2 - Helium low temperature purifier and operating method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a helium low-temperature purifier and a method for operating the same, and more particularly, to recovering or circulating helium used for cooling in various experiments, for example, cooling a superconducting magnet, and reusing it. At this time, the present invention relates to a helium low-temperature purifier for purifying helium by separating impurities, for example, air components, mixed in the helium, and an operation method thereof.

[0002]

2. Description of the Related Art In general, in a cooling facility or the like using liquid helium, helium after cooling an object to be cooled is recovered or circulated, and impurities such as air or the like are contained in the helium. When these are mixed, there is a possibility that these impurities precipitate in the piping or equipment of the helium liquefaction system in an extremely low temperature state and block the flow path.

Therefore, it is necessary to remove these impurities before cooling the helium to an extremely low temperature. If the amount of the impurities is large, the helium gas containing the impurities is cooled to an appropriate temperature. For example, it is cooled to about 80 K to liquefy an impurity component having a high boiling point, and the liquefied impurity component is separated using a gas-liquid separation means such as a gas-liquid separator.

FIG. 2 shows an example of a helium low-temperature purifier having the gas-liquid separation means. This helium low-temperature purifier has a pipe 1 for introducing helium gas containing impurities.
And a heat exchanger 2 for cooling the helium gas containing the impurities by heat exchange with the purified helium gas, and a gas exchanger disposed in a liquefied nitrogen storage tank 3 maintained at about 80 K to liquefy the impurities. A liquid empty bottle 4 serving as a liquid separating means, an adsorber 5 for adsorbing and removing trace impurities contained in a gas phase separated by the liquid empty bottle 4, and a liquefied component discharge for discharging the liquid phase separated by the liquid empty bottle 4 And means 6.

The liquefied component discharging means 6 includes a discharge pipe 7 connected to the bottom of the empty liquid bottle 4, a discharge valve 8 and a flow control valve 9 provided on the discharge pipe 7, and opens and closes the discharge valve 8. And a timer 10 to be activated.

The timer 10 opens and closes the discharge valve 8 at a predetermined cycle, and the cycle is set according to the amount of impurities in the helium introduced from the pipe 1.

For example, if the liquefied amount of impurities in the liquid empty bottle 4 is 6 liters per hour, the liquid capacity of the liquid empty bottle 4 is 6 liters, and the liquid flow rate set in the flow control valve 9 is 1 liter per minute, the discharge valve 8 Is opened every hour for about 7 minutes to discharge the liquefied component in the bottle.

[0008]

However, in order to prevent impurities from flowing to the adsorber 5 side to exceed the adsorbing capacity of the adsorber 5 and to leave impurities in the purified helium, the discharge valve 8 must be provided. The opening interval and the opening time must be set according to the time when the impurity in the helium introduced from the tube 1 is the highest.

For this reason, when the amount of impurities contained in the helium introduced from the pipe 1 is small, the time during which the discharge valve 8 is open is longer than the amount of liquid generated in the empty liquid bottle 4. In addition, there is a disadvantage that helium gas is also discharged.

On the other hand, as an automatic control for discharging the liquid thus generated, generally, a liquid level in a liquid empty bottle 4 is detected, and a discharge valve 8 is opened and closed according to the liquid level. However, in a helium low-temperature purifier, it is difficult to apply a differential pressure type liquid level gauge due to its structure, and the internal pressure is as high as about 150 atm and the temperature is low. It is also difficult to install a capacitance type liquid level gauge on the cut surface so as to prevent leakage, and in any case, an expensive apparatus is required, which is not practical.

Therefore, the present invention provides a helium discharge apparatus which controls the opening and closing of the discharge valve, in particular, the timing of closing the valve appropriately according to the state of discharge of the liquid, thereby greatly reducing the amount of helium discharge even in fully automatic operation. It is an object of the present invention to provide a low-temperature purifier and a method of operating the same.

[0012]

In order to achieve the above object, a helium low-temperature purifier of the present invention comprises means for cooling helium gas containing impurities, and separating the helium gas from the impurities liquefied by the cooling. Gas-liquid separation means,
Means for discharging the liquefied component separated by the gas-liquid separation means, wherein the means for discharging the liquefied component from the gas-liquid separation means comprises a discharge valve and a flow rate control provided in a liquefied component discharge pipe. A valve, a timer for opening the discharge valve at a predetermined cycle, and a pressure upstream of the flow control valve or a differential pressure before and after the flow control valve to detect a change in the pressure or the differential pressure. Control means for closing the discharge valve.

In the method for operating a helium low-temperature purifier according to the present invention, the helium gas containing impurities is cooled to a temperature at which the impurities are liquefied, introduced into gas-liquid separation means, and separated by the gas-liquid separation means. A method for operating a helium low-temperature purifier that discharges a liquefied component and separates helium gas and impurities, wherein the liquefied component separated by the gas-liquid separation means is provided with a discharge valve provided in a liquefied component discharge pipe having a flow control valve. When the valve is opened at a predetermined cycle by a timer to start discharging the liquefied component, and when the pressure or the differential pressure changes by detecting the pressure upstream of the flow control valve or the differential pressure across the flow control valve. And the discharge of the liquefied component is terminated by closing the discharge valve.

[0014]

[Operation] According to the above configuration, when all the liquefied components are discharged from the gas-liquid separation means and the gas components are discharged, the difference between the ventilation resistance and the liquid flow resistance in the flow control valve causes the upstream side of the discharge valve to be discharged. The pressure and the differential pressure before and after the flow control valve change. By detecting the change in the pressure or the differential pressure and closing the discharge valve, the discharge amount of the helium gas can be reduced.

If the discharge valve opening cycle is set on the basis of the case where the amount of impurities contained in helium introduced into the helium purification system is the largest as in the conventional case, the liquid impurity is not separated by gas-liquid separation. Can be prevented from overflowing.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail based on one embodiment shown in FIG . The same elements as those of the conventional example shown in FIG. 2 are denoted by the same reference numerals, and detailed description thereof will be omitted.

In the apparatus of this embodiment, a helium gas containing impurities is introduced from a pipe 1 as in the prior art, cooled by a heat exchanger 2, and then a liquid empty bottle 4 in a liquefied nitrogen storage tank 3 maintained at about 80K. To separate helium gas and liquefied impurity components.

The helium gas in the liquid empty bottle 4 is removed by adsorption of a trace amount of impurities by an adsorber 5 and then recovered as purified helium through the heat exchanger 2 or used for circulation.

The liquefied component in the empty liquid bottle 4 is discharged from the discharge pipe 7 having the discharge valve 8 and the flow control valve 9 as described above. In the present invention, the timer 1 as a means for starting the liquid discharge from the discharge pipe 7, that is, opening the discharge valve 8.
And a pressure gauge (P) 12 for detecting the pressure of the helium introduction pipe 1 or a difference between before and after the flow control valve 9 as means for terminating the liquid discharge, that is, closing the discharge valve 8. A differential pressure gauge (DP) 13 for detecting pressure is provided.

The timer 11 sets an appropriate valve opening cycle in accordance with the maximum impurity content in the helium gas introduced from the pipe 1 and the liquid volume of the liquid empty bottle 4 in the same manner as described above. If the maximum liquefaction amount of impurities is 6 liters / hour and the liquid volume of the empty liquid bottle 4 is 6 liters as described above, the valve is set to open at least every hour.

On the other hand, the pressure gauge 12 and the differential pressure gauge 13 detect the termination of liquid discharge based on the difference between the gas flow resistance and the liquid flow resistance in the flow control valve 9. That is, when the discharge of the liquid from the liquid empty bottle 4 is completed and the gas (helium gas) is discharged from the flow control valve 9, the gas in the system is discharged.
Since the pressure is released , the pressure in the helium purification system upstream of the flow control valve 9 temporarily decreases, and the flow resistance of the flow control valve 9 increases.

Therefore, after the discharge valve 8 is opened, the pressure of the helium gas introduced into the pipe 1 is monitored by the pressure gauge 12 and the discharge valve 8 is closed when the pressure decreases. By monitoring the differential pressure across the flow control valve 9 with the pressure gauge 13 and closing the discharge valve 8 when the differential pressure rises, the discharge of gas (helium gas) from the liquid empty bottle 4 is minimized. can do. The operation of closing the discharge valve 8 based on the detection value of the pressure gauge 12 or the differential pressure gauge 13 can be performed by well-known valve driving means using an electromagnetic valve or the like.

Here, as the specifications of the helium low-temperature purifier, when the processing amount is 100 Nm ³ / h, the pressure is 150 atm, and the inlet impurity concentration is 5% by volume (the impurity is air), the helium gas containing the air as an impurity is about 80K. When cooled to a gas-liquid two-phase state, the gas is 96.3 Nm ³ / h,
The ratio of the liquid is 3.7 Nm ³ / h. Therefore, the amount of generated liquid air is about 6 liters / h, and the cycle of opening the discharge valve 8 can be determined based on the volume of the empty liquid bottle 4.

On the other hand, since the operation of closing the discharge valve 8 is performed by detecting the pressure change when the liquid air is completely discharged and the gas is discharged as described above, the impurity level given in the above specification decreases. Even when the amount of generated liquid decreases, the amount of helium gas discharged can be minimized.

It should be noted, by setting shorter period of opening the discharge valve 8, the impurity level for some reason
Even if it rises suddenly , the liquid air
It can be prevented from accumulating inside and reaching the low-temperature adsorption cylinder 5, and the reliability of the apparatus can be improved. In addition, auxiliary liquid in empty liquid bottle 4
The provided float constitutes the outlet portion of the gas outlet pipe Ekisora bottle so as to close by the rise of the float, any
When suddenly liquid level in Kano due rises, float Ide busy the gas outlet portion, the liquid in the low-temperature adsorption column 5 from Ekisora bottle 4
If body pressure is prevented from flowing, and the pressure gauge 12 detects a rise in pressure and opens the discharge valve 8 ,
In the event of an emergency, regardless of the opening operation of the discharge valve 8 by the
Since the discharge valve 8 can be opened,
Excessive accumulation can be prevented .

Further, when the discharge valve 8 is closed by the pressure gauge 12, even when the level of impurities at the inlet is extremely small and gas-liquid separation cannot be performed, the gas is discharged and the pressure in the system decreases at the same time. Therefore, the discharge valve 8 can be closed immediately upon detecting this, and the differential pressure gauge 13
If the pressure difference is set between when the liquid is discharged and when the gas is discharged, the discharge of the gas can be detected and the discharge valve 8 can be closed in the same manner. Therefore, even when there is no liquid in the empty liquid bottle 4 at the start of discharge, the discharge amount of helium gas can be suppressed.

In addition, in the existing helium low-temperature purifier, the above-mentioned pressure gauge or differential pressure gauge is installed.
It can be implemented simply by adding a simple control system, and can be implemented extremely easily without largely changing the device configuration.

In FIG. 1, the pressure gauge 12 and the differential pressure gauge 13 are displayed at the same time. However, in an actual apparatus, only one of them may be installed. At the start, any portion that can detect a pressure change due to this can be used arbitrarily, and can be set as appropriate according to the device configuration. Further, a fixed throttle such as an orifice can be used as the flow control valve 9, and if the discharge valve 8 has a flow control function,
The discharge valve 8 can also serve as a flow control valve.

[0029]

As described above, according to the present invention,
Liquefied components, which are impurities, can be reliably discharged, and
The amount of discharged helium gas can be minimized, and the running costs of various cooling facilities using liquefied helium can be reduced. Further, since an expensive detector is not required, the structure of the apparatus is simple, and the configuration of the entire low-temperature purifier may be a conventional type, the manufacturing cost can be reduced.

Further, even when the level of impurities in the helium gas to be purified fluctuates, the operation is effective, so that the automatic operation is extremely easy.

[Brief description of the drawings]

FIG. 1 is a system diagram showing one embodiment of a helium low-temperature purifier of the present invention.

FIG. 2 is a system diagram showing a main part of a conventional helium low-temperature purifier.

[Explanation of symbols]

2 heat exchanger 3 liquefied nitrogen storage tank 4 liquid empty bottle 5 adsorber 7 discharge pipe 8 discharge valve 9 flow control valve
11: Timer 12: Pressure gauge 13: Differential pressure gauge

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F25J 1/00-5/00

Claims (2)

(57) [Claims] 1. Means for cooling helium gas containing impurities, gas-liquid separation means for separating helium gas from the impurities liquefied by the cooling, and means for discharging liquefied components separated by the gas-liquid separation means Wherein the means for discharging liquefied components from the gas-liquid separation means comprises a discharge valve and a flow control valve provided on a liquefied component discharge pipe, and a timer for opening the discharge valve at a predetermined cycle. And control means for detecting a pressure upstream of the flow control valve or a differential pressure before and after the flow control valve, and closing the discharge valve by a change in the pressure or the differential pressure. Helium cryogenic purifier. 2. A helium gas containing impurities is cooled to a temperature at which the impurities are liquefied and introduced into gas-liquid separation means, and a liquefied component separated by the gas-liquid separation means is discharged to separate helium gas and impurities. In the operation method of the helium low-temperature purifier to be separated, the liquefied component separated by the gas-liquid separation means is opened at a predetermined cycle by a timer with a discharge valve provided in a liquefied component discharge pipe having a flow control valve, and the liquefied component is separated. While discharging, the pressure upstream of the flow control valve or the differential pressure before and after the flow control valve is detected, and when the pressure or the differential pressure changes, the discharge valve is closed to discharge the liquefied component. A method for operating a helium low-temperature purifier, which is terminated.