JPH09323017A - Large-sized low temperature gas purifier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a large-sized low temperature gas purifier in which the consumption of a liquid nitrogen refrigerant is reduced, and the dissipated quantity of gas to be purified is decreased, and also the evacuation time is shortened. SOLUTION: This gas purifier is provided with a first heat exchanger 23 for cooling gas to be purified of room temperature to the temperature level of liquid nitrogen, second heat exchangers 25a, 25b for cooling the gas to be purified by a nitrogen refrigerant at the prestage of plurally installed adsorbers 3a, 3b, precooling routes 29a, 29b which are branched off from outlet routes 27a, 27b for purified gas brought out from adsorbers to be connected to inlet routes 28a, 28b for the gas to be purified of the other adsorbers, and a regenerated gas circulating route 36 which is branched off from the purified gas outlet routes 27a, 27b and join the gas to be purified inlet routes 28a, 28b of the same adsorbers through a blower and a heater 33.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a large-sized low-temperature gas purifier, for example, a large-sized low-temperature gas purifier for purifying a low boiling point gas such as helium gas or hydrogen gas.

[0002]

2. Description of the Related Art Conventionally, a large-scale low-temperature gas purifier for purifying helium, hydrogen gas, etc. has a refrigerant liquid immersion type heat exchanger for cooling a gas to be purified containing impurities and an adsorbent for removing impurities. It had a configuration in which multiple cold boxes containing a set of adsorption cylinders that repeat adsorption and regeneration were installed.

FIG. 2 is a system diagram showing an example of a conventional large-scale low-temperature gas purifier, which is a large-scale helium purifier for purifying impure helium gas containing mainly air components such as nitrogen and oxygen as impurities. is there.

This large-scale helium purifier is comprised of heat exchangers 1a and 1b for exchanging heat between the introduced impure helium gas and the purified high-purity helium gas, and the cooled impure helium gas as a liquid refrigerant. Two cold boxes 4a containing the refrigerant liquid immersion type heat exchangers 2a and 2b for further cooling with nitrogen, and the adsorption cylinders 3a and 3b for adsorbing and removing the impurities in the impure helium gas by the adsorbent filled therein. 4b and liquid nitrogen storage tank 5 for storing liquid nitrogen
An evaporator 6 for vaporizing liquid nitrogen to obtain the regenerating nitrogen gas in the adsorption columns 3a, 3b, a heater 7 for raising the temperature of the regenerating nitrogen gas, and impurities adsorbed in the adsorption columns 3a, 3b. It is composed of a vacuum pump 8 that is desorbed by heating regeneration and sucked and removed to the outside of the system, and pipes and valves that connect these devices.

In the following, referring to FIG. 2, the cold box 4
The case where the a side is the regeneration process and the cold box 4b side is the adsorption process will be described. For example, impure helium gas mixed with impurities such as oxygen and nitrogen in the liquefaction process step in a helium liquefaction device (not shown) is extracted from the helium liquefaction device and the like, and is a component that solidifies in advance at a low temperature in equipment such as a dryer, for example, water. After removing carbon dioxide and the like, it is introduced into this large-scale helium purifier, and the inlet valve 11b on the cold box 4b side, the heat exchanger 1b, the refrigerant liquid immersion type heat exchanger 2
After cooling to the liquid nitrogen temperature level via b, the adsorption cylinder 3
b. Then, impurities are adsorbed and removed by the adsorbent filled in the adsorption column 3b to form high-purity helium gas, and heat is exchanged with the impure helium gas in the heat exchanger 1b, and the temperature becomes normal temperature from the outlet valve 12b. It is led out and returned to the helium liquefier.

During the adsorption process, the coil 9b attached to the outside of the adsorption cylinder 3b is provided with a slight amount of liquid nitrogen in order to compensate for the cold which is commensurate with the heat of adsorption in the adsorption cylinder 3b and the heat of invasion from the outside. For example, it is supplied from the liquid nitrogen supply valve 13b under the control of a liquid level controller (not shown) provided in the refrigerant liquid immersion type heat exchanger 2b.

On the other hand, on the cold box 4a side, in order to regenerate the adsorbent in the adsorption cylinder 3a, the inlet valve 11a, the outlet valve 12a and the liquid nitrogen supply valve 13a of the helium gas system are closed and the refrigerant liquid immersion type heat exchange is performed. The liquid removal valve 14a of the container 2a is opened to discharge the liquid nitrogen inside the system to the outside of the system. Then, after opening the valve 15a to release the residual pressure in the helium gas system to the outside of the system, the valve 16a is opened, the liquid nitrogen from the liquid nitrogen storage tank 5 is vaporized by the evaporator 6, and the temperature is raised to room temperature or higher by the heater 7. The heated heated nitrogen gas is caused to flow through the valve 16a, the adsorption cylinder 3a, the refrigerant liquid immersion type heat exchanger 2a, and the valve 15a to heat and regenerate the adsorbent in the adsorption cylinder 3a. When this is over,
Close the valves 15a and 16a and open the vacuum exhaust valve 17a,
The vacuum pump 8 is started to evacuate the helium gas system, and the impurities mainly composed of nitrogen in the system are discharged to the outside of the system. In this operation, in order to promote the removal of impurities, the vacuum exhaust valve 17a is once closed, and the impure helium gas inlet valve 11 is closed.
The replacement vacuum evacuation operation in which a is opened to replace the inside of the adsorption cylinder 3a with impure helium gas, the inlet valve 11a is closed, the vacuum exhaust valve 17a is opened, and vacuum exhaust is performed again is repeated a plurality of times.

When the displacement vacuum exhaust is performed and the removal of impurities is completed, cooling of the adsorption cylinder 3a is started in preparation for the next adsorption step. That is, the liquid nitrogen supply valves 13a and 18a
And liquid nitrogen is introduced from the liquid nitrogen storage tank 5 to cool and store the inside of the refrigerant liquid immersion type heat exchanger 2a via the liquid nitrogen supply valve 18a, and a coil 9a attached to the outside of the adsorption cylinder 3a. Liquid nitrogen is caused to flow through the liquid nitrogen supply valve 13a to cool the adsorption cylinder 3a. The nitrogen gas in both paths, which has been gasified during cooling, is released from the valve 19a to the atmosphere.

Then, when the liquid storage in the refrigerant liquid immersion type heat exchanger 2a and the cooling temperature of the adsorption cylinder 3a reach a specified value, the helium gas system is switched. That is, the inlet valve 11a and the outlet valve 12a are opened, and the inlet valve 11b and the outlet valve 1 are opened.
By closing 2b, this time the cold box side 4
The a side is in the adsorption process, and the cold box 4b side is in the regeneration process. By repeating this process alternately, a continuous refining operation is performed. Note that, in FIG. 2, valves having the same action in both systems are denoted by the same numerals and symbols a and b.

[0010]

As described above, in the conventional large-sized low-temperature gas purifier, liquid is stored in the refrigerant liquid immersion type heat exchangers 2a and 2b prior to the regeneration of the adsorption columns 3a and 3b. A large amount of liquid nitrogen is completely released, and the nitrogen gas introduced from the liquid nitrogen storage tank 5 is used as a heating gas during the heating regeneration step and is discharged to the outside of the system without being circulated. Further, in the cooling step of precooling the adsorption column, a large amount of liquid is required to be stored again in the refrigerant liquid immersion type heat exchangers 2a and 2b, which results in a large consumption of the refrigerant liquid nitrogen. In addition, since nitrogen is used as a heating gas, most of the in-system gas that is sucked out of the system by vacuum evacuation after regeneration is a nitrogen component, so the number of times of displacement evacuation increases. , The amount of gas to be purified that escapes to the outside of the system increases due to displacement vacuum exhaustion,
There was an inconvenience that it took time to evacuate.

Therefore, the present invention reduces the consumption of refrigerant liquid nitrogen, reduces the amount of gas to be purified that is dissipated by the displacement vacuum exhaust, and shortens the vacuum exhaust time. Is intended to provide.

[0012]

In order to achieve the above object, the large-sized low-temperature gas purifier of the present invention is a large-sized low-temperature gas purification for removing impurities in a gas to be purified, particularly helium gas or hydrogen gas by low-temperature adsorption. In the reactor, a first heat exchanger for cooling the purified gas at room temperature with refrigerant nitrogen, an adsorption cylinder for adsorbing and removing impurities in the purified gas by switching and using a plurality of them, and cooling the adsorption cylinder with refrigerant nitrogen A coil to
A second heat exchanger for cooling the low-temperature gas to be purified, which is introduced into the adsorption cylinder before the adsorption cylinder, with refrigerant nitrogen.

Further, according to the present invention, the first heat exchanger has a hot heat exchange section and a cold heat exchange section, and the cold heat exchange section circulates liquid nitrogen by a thermosyphon effect to cool the gas to be purified. Is characterized by. Furthermore, a pre-cooling path branched from the purified gas outlet path of the adsorption column and connected to the refined gas inlet path of another adsorption column is provided, and a pre-cooling path branched from the purified gas outlet path of the adsorption column is provided with a blower and a heater. A regeneration gas circulation path connected to the refined gas inlet path of the adsorption column via is provided, and the blower inlet side gas and the blower outlet side gas of the regeneration gas circulation path are heat-exchanged to raise the blower inlet side gas. The feature is that a heat exchanger for regeneration for heating is provided.

According to the above configuration, each time the suction cylinder is switched,
Since it is not necessary to store liquid nitrogen in the refrigerant liquid immersion type heat exchanger or to release the stored liquid nitrogen, it is possible to reduce the consumption amount of the refrigerant liquid nitrogen.

Further, by providing the regeneration gas circulation path, the gas to be purified remaining in the adsorption cylinder can be circulated and used as the heating regeneration gas instead of nitrogen, and the number of replacement vacuum exhaust after regeneration can be reduced. Therefore, it is possible to reduce the amount of gas to be purified that is dissipated by the displacement vacuum exhaust, and it is possible to shorten the vacuum exhaust time. Further, by providing the pre-cooling path, it is possible to reduce the consumption amount of the refrigerant liquid nitrogen.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail below with reference to FIG. The same elements as those in the conventional example are designated by the same reference numerals, and detailed description thereof will be omitted. Further, the same numerals and symbols a and b are attached to the valves and paths having the same action in both systems.

FIG. 1 is a system diagram showing an example in which the large-sized low-temperature gas purifier of the present invention is used to purify helium gas.
This large-scale helium gas purifier is equipped with an adsorption column 3a for switching a plurality of normal temperature impure helium gases to be used,
Before being introduced into 3b, a first cold box 24 containing a first heat exchanger 23 consisting of a heat exchanger 21 and a heat exchanger 22 for cooling to a liquid nitrogen temperature level,
Adsorption cylinders 3a, 3b and a plurality of second and third cold boxes 26a for accommodating the second heat exchangers 25a, 25b provided in front of the adsorption cylinders 3a, 3b as one set, respectively.
26b and the purified gas outlet path 27 of each adsorption cylinder 3a, 3b
a precooling path 29 branched from a and 27b and connected to the purified gas inlet paths 28a and 28b of the other adsorption columns 3a and 3b.
a, 29b and precooling valves 30a, 30b for adsorbing cylinder precooling, and residual pressure of the adsorbing cylinders 3a, 3b is branched from each purified gas outlet passage 27a, 27b to a passage 31a, 31b. After passing through the blower 32 for increasing the pressure, the heater 33 for raising the temperature, and the regeneration heat exchanger 34 for heating the inlet side gas and the outlet side gas of the blower 32 to raise the temperature of the inlet side gas, the paths 35a, 35b are It is composed of a regenerated gas circulation path 36 connected to each of the purified gas inlet paths 28a and 28b via the liquid nitrogen storage tank 5, the evaporator 6, the vacuum pump 8 and a path and a valve connecting these devices. There is.

The first heat exchanger 23 may be of an integrally-molded type, but in the present embodiment, the warm heat exchange section 21 and the cold heat exchange section 22 are separately formed, and the cold heat exchange section 22 is made of liquid nitrogen. By circulating the liquid nitrogen in the reservoir 37 by the thermosiphon effect, the impure helium gas introduced from the introduction path 38 into the system of the large-sized low-temperature gas purifier is cooled.

The operation for purifying helium gas by the large helium gas purifier of this embodiment will be described below. Impurity helium gas from a helium liquefier (not shown), for example, impure helium gas having an impurity content of about 1000 ppm is removed from the first cold passage from the introduction path 38 after components such as water that solidify at low temperature are removed in the same manner as in the conventional case. It is installed in the box 24. The impure helium gas introduced into the first cold box 24 is absorbed by the adsorption column 3a,
In the warm heat exchange section 21 of the first heat exchanger 23 for commonly cooling the impure helium gas before being introduced into 3b, the purified high temperature pure helium gas and the liquid nitrogen reservoir 3 to be returned.
It is cooled by exchanging heat with the low temperature nitrogen gas supplied from 7.
Subsequently, the cold heat exchange section 22 exchanges heat with the liquid nitrogen from the liquid nitrogen reservoir 37, and the liquid nitrogen is cooled to the liquid nitrogen temperature level by the sensible heat and the latent heat of the liquid nitrogen.

The liquid nitrogen in the cold heat exchange section 22 is
By cooling the impure helium gas, the temperature of the liquid nitrogen itself rises and a part of the liquid nitrogen is gasified, and this gas produces a thermosiphon effect that gives a lift to the liquid nitrogen. The liquid nitrogen in 37 flows through the path 37 i, the cold heat exchange unit 22, and the path 37 o and circulates in the liquid nitrogen reservoir 37. Then, in this circulating flow, by cooling the impure helium gas in the cold heat exchange section 22, a part of the liquid nitrogen is gasified to become the nitrogen gas at the saturation temperature, and this nitrogen gas exchanges the heat through the path 37g. The impure helium gas at room temperature supplied to the part 21 and introduced into the heat exchange part 21 is given a cold equivalent to sensible heat up to room temperature to heat itself, and is discharged to the outside of the system through the path 39 and the valve 40. To be done.

At this time, the amount of liquid nitrogen corresponding to the above-mentioned nitrogen gas released to the outside of the system is passed from the liquid nitrogen storage tank 5 to the path 4
1, the liquid nitrogen reservoir 37 is replenished through the liquid nitrogen supply valve 42 controlled by a liquid level controller (not shown) provided in the liquid nitrogen reservoir 37.

As described above, by adopting the thermosiphon heat exchanger as the cold heat exchanging portion 22 of the first heat exchanger 23 and separately configuring it with the heat exchanger forming the heat exchanging portion 21, it is integrally formed. It is possible to prevent pressure fluctuation due to boiling evaporation of liquid nitrogen on the refrigerant side, which easily occurs in the case of, and instability of heat exchange temperature due to entrainment of liquid droplets in the heat exchange part,
Stable operation can be performed efficiently and effectively using the sensible heat and the latent heat of liquid nitrogen.

The impure helium gas cooled to the liquid nitrogen temperature level in the cold heat exchange section 22 of the first heat exchanger 23 is led out from the first cold box 24 to the low temperature impure gas introduction path 43 and then subjected to the adsorption step. Is introduced into the adsorption cylinder. Hereinafter, the description will be made assuming that the adsorption cylinder 3b performs the adsorption process and the adsorption cylinder 3a performs the regeneration process.

The impure helium gas flows from the low temperature impure gas introduction path 43 to the branch path 43b side, and is introduced from the inlet valve 44b to the purified gas inlet path 28b to the second heat exchanger 25b in the third cold box 26b. , Coil 9b
The liquid nitrogen is cooled by exchanging heat with a small amount of liquid nitrogen led to the path 45b.

The low temperature impure helium gas cooled by the second heat exchanger 25b is cooled by a small amount of liquid nitrogen flowing through the coil 9b attached to the outer circumference of the cylinder 3b.
The impurities are adsorbed and removed by the adsorbent introduced into the cylinder and filled in the cylinder. As a result, for example, high-purity helium gas having an impurity content of 1 ppm or less is discharged from the adsorption column 3b to the purified gas outlet path 27b.

The liquid nitrogen supplied to the coil 9b when the adsorption column 3b is in the adsorption step is the second heat exchanger 25b.
The flow rate is adjusted by the liquid nitrogen supply valve 13b controlled by a thermometer (not shown) for measuring the temperature of the low temperature impure helium gas at the outlet, and the liquid nitrogen storage tank 5 to the liquid nitrogen path 46,
It is supplied at a predetermined flow rate via 46b.

The liquid nitrogen flowing through the coil 9b and the second heat exchanger 25b is the low temperature impure gas introduction path 43, the branch path 43b, and the inlet valve 4 through which the low temperature impure helium gas flows.
4b, the gas to be purified inlet 28b and the invasion heat in the third cold box 26b and the heat of adsorption in the adsorption cylinder 3b are compensated.

The high-purity helium gas flowing through the purified gas outlet path 27b and led out from the third cold box 26b is branched from the outlet valve 47b into a branch path 48b and a high-purity gas outlet path 48.
After returning to the first cold box 24, the heat exchanging part 21 of the first heat exchanger 23 exchanges heat with the impure helium gas at room temperature introduced through the introduction path 38 to cool the impure helium gas. First cold box 24
To obtain high-purity helium gas at room temperature and return path 4
Returned to the helium liquefier from 9.

On the other hand, on the side of the adsorption cylinder 3a in which the regeneration process is performed, first, the inlet valve 44a and the outlet valve 47a are closed,
The helium gas system is cut off from the adsorption cylinder 3b side system. At the same time, the liquid nitrogen supply valve 13a is also closed, and a discharge valve (not shown)
The liquid nitrogen in the coil 9a is discharged to the outside of the system via the. Therefore, the amount of liquid nitrogen released when switching from the adsorption process to the regeneration process is only the amount that remains in the coil 9a, and this amount was stored and released in the conventional refrigerant liquid immersion heat exchanger. It is much smaller than the amount, and the consumption of liquid nitrogen can be greatly reduced.

Next, the purified gas outlet path 2 of the adsorption column 3a
In the system, the circulation valve 50a of the path 31a branched from 7a or a release valve (not shown) is opened to release the low temperature helium gas in the system and detected by, for example, a pressure gauge provided at the adsorption cylinder inlet 51a of the adsorption cylinder 3a. The pressure inside the system is reduced until the pressure reaches a predetermined pressure. At this time, the pressure in the helium system that decreases with the release time is controlled by the pressure control valve (PIC) 52 provided in the regeneration gas circulation path 36.
The pressure is adjusted and maintained at a predetermined pressure by 3.

The residual pressure in the adsorption cylinder 3a is a specified value, for example, 0.
When the pressure drops to 1 kg / cm ² G, the adsorption cylinder heating valve 54a
To open the blower 32 and the heater 33. As a result, the regeneration gas circulation path 36 is established, and the adsorption cylinder 3
The heating and regenerating process of the adsorbent in the adsorption column 3a by the helium gas remaining in a is started. That is, the helium gas in the adsorption cylinder 3a is supplied to the purified gas outlet path 27 on the cylinder outlet side.
a, through the circulation valve 50a, into the regeneration gas circulation path 36, from the regeneration heat exchanger 34 to the blower 32, the heater 3
3 to reach the path 35a, the adsorption cylinder heating valve 54a, the adsorption cylinder inlet portion 51a to flow into the adsorption cylinder 3a, and the gas is again guided to the purified gas outlet path 27a and circulates in this path.

During this circulation, in the regeneration heat exchanger 34, the low temperature helium gas led out from the adsorption column 3a to the regeneration gas circulation path 36 is heated by the compression heat generated when the blower 32 pressurizes the helium gas. And heat up to raise the temperature. Further, in the blower 32, a pressure corresponding to the flow path resistance of the circulation path is applied, and in the heater 33 controlled by the temperature controller (TIC) 55, it is heated to a predetermined temperature for regeneration, for example, 50 ° C.

At the beginning of the regeneration process, the helium gas discharged from the adsorption column 3a is at a low temperature of approximately liquid nitrogen temperature level, so that the temperature of the helium gas is raised, as shown by the broken line in FIG. The circulation gas heating path 56 is connected to the introduction path 38 through which the impure helium gas at room temperature is introduced, and
The flow path switching valves 57c and 57d are provided so that the temperature of the circulating helium gas derived from the adsorption cylinder 3a is 1 at the initial stage of the regeneration process.
Until the temperature is raised to about 0 ° C., the room temperature impure helium gas introduced into the large-scale helium gas purifier is supplied to the valve 57c.
By closing the valve and opening the valve 57d.
Alternatively, it may be introduced into the regeneration heat exchanger 34 to cool the low-temperature circulating helium gas. This allows
The temperature of the heat exchanger 34 for regeneration can be prevented from lowering, and the introduced impure helium gas at normal temperature is introduced into the heat exchanger 34 for regeneration.
The amount of the refrigerant liquid nitrogen consumed in the first heat exchanger 23 can be reduced by the amount of the cooling performed in Step 1.

The temperature of the entire regeneration gas circulation path 36 rises due to the progress of the heating regeneration step in the adsorption cylinder 3a, and the pressure in the system rises accordingly. In this case, the pressure is instructed by the pressure controller 52. The regulating valve 53 is opened and the gas in the system is released to the outside of the system. On the contrary, if the pressure in the system falls below the specified value due to an operation error, the nitrogen gas supply valve 58 is opened by the instruction of the pressure controller 52, and the liquid nitrogen in the liquid nitrogen storage tank 5 is evaporated. After evaporating in 6, the nitrogen gas for backup is introduced into the regeneration gas circulation path 36. As a result, the inside of the system is always maintained within the predetermined pressure range.

Further, since the inlet gas of the heater 33 is heat-exchanged with the low-temperature circulating helium gas in the regeneration heat exchanger 34, the temperature of the adsorbing cylinder 3a rises, that is, the temperature of the circulating helium gas rises and the heater heats up. The load of 33 is reduced, and the power consumption of the heater 33 can be reduced.

The heating and regeneration of the adsorption cylinder 3a is performed by, for example, a thermometer (not shown) provided at the adsorption cylinder outlet 59a of the adsorption cylinder 3a.
Is detected by detecting the temperature equal to or higher than the specified temperature, the circulation valve 50a and the adsorption cylinder heating valve 54a are closed, and then the adsorption cylinder 3 is closed.
Since the adsorbent in a discharges the adsorbed impurities out of the system,
The vacuum exhaust valve 17a is opened and the vacuum pump 8 is activated to evacuate the adsorption cylinder 3a to discharge impurities from the exhaust path 60 to the outside of the system.

In this case, in this embodiment, the helium gas remaining in the adsorption column 3a is used as the regeneration gas, and nitrogen is not used as in the conventional case. Therefore, the nitrogen in the heating regeneration step should be zero. In addition to being able to reduce the consumption of the liquid nitrogen in the refrigerant, in the vacuum evacuation step, compared with the case where nitrogen gas is used for heating regeneration, the amount of impurity components in the gas evacuated from the adsorption cylinder 3a is reduced. Since a certain nitrogen component is small, the number of times of displacement evacuation is small,
As a result, it is possible to reduce the amount of helium gas that is dissipated by the displacement evacuation, and it is possible to shorten the time required for evacuation.

To determine the completion of the impurity removal step by vacuum evacuation, the absolute amount of impurities desorbed during regeneration is calculated from the content of impurities in the introduced impure helium gas, the adsorption pressure, the adsorption step time, etc. The number of times of vacuum evacuation calculated based on the difference between the regeneration pressure and the vacuum evacuation pressure may be used, or the amount of impurities may be confirmed by analyzing the gas in the system.

The adsorption cylinder 3a from which impurities have been removed then enters a cooling step. In this cooling step, the precooling valve 30a of the precooling path 29a branched from the purified gas outlet path 27a of the adsorption cylinder 3a is opened, the inlet valve 44a of the adsorption cylinder 3a is slightly opened, and the inlet valve 44b of the adsorption cylinder 3b is slightly opened. Close,
A part of the low-temperature impure helium gas having the liquid nitrogen temperature level introduced from the low-temperature impure gas introduction path 43 is branched into the branch path 43a by adjusting the openings of the both inlet valves 44a, 44b, and the purified gas inlet path 28a and The gas to be purified is introduced into the adsorption column 3a via the second heat exchanger 25a, the adsorbent inside is cooled and led to the purified gas outlet route 27a, and the pre-cooled route 29a is introduced into the adsorption column 3b to be introduced into the adsorption column 3b. 28b is mixed with impure low temperature helium gas. As a result, the suction cylinder 3a
The adsorbent therein is cooled by low temperature impure helium gas at the liquid nitrogen temperature level.

On the other hand, at the same time, the liquid nitrogen supply valve 13a and the adsorption cylinder precooling nitrogen outlet valve 61a are opened, and the liquid nitrogen from the liquid nitrogen storage tank 5 is supplied to the coil 9a attached to the outside of the adsorption cylinder 3a. 46, the liquid nitrogen supply valve 13a and the liquid nitrogen passage 46a to introduce the adsorption cylinder 3a indirectly. During this cooling step, the liquid nitrogen flowing through the coil 9a vaporizes and rises in temperature, so after it is led out of the coil 9a, it is discharged from the nitrogen gas exhaust path 62a to the outside of the system via the adsorption cylinder precooling nitrogen outlet valve 61a. , Second heat exchanger 25
Prevent a from warming up.

By this cooling step, when the adsorption cylinder 3a has a predetermined temperature, for example, a thermometer (not shown) provided at the outlet 59a of the adsorption cylinder 3a detects a temperature equal to or lower than the predetermined temperature and pre-cooling is completed, the adsorption cylinders 3a and 3b are cooled. Switch over. That is, the inlet valve 44a and the outlet valve 47a on the adsorption cylinder 3a side are opened, the inlet valve 44b and the outlet valve 47b on the adsorption cylinder 3b side are closed, and the precooling valve 30a and the adsorption cylinder precooling nitrogen outlet valve 61a on the precooling path 29a are closed. By closing, the adsorption column 3a is switched to the adsorption step and the adsorption column 3b is switched to the regeneration step, and the helium gas refining operation is continuously performed.

As described above, even in the cooling process for precooling the adsorption cylinder 3a, the adsorption cylinder 3a and the adsorbent inside are cooled by the low temperature impure helium gas at the liquid nitrogen temperature level. As described above, since it is not necessary to store a large amount of liquid nitrogen in the refrigerant liquid immersion type heat exchanger, the consumption amount of the refrigerant liquid nitrogen can be significantly reduced.

In the above embodiment, the first heat exchanger 23
The case where the heat exchanger that forms the heat exchanger 21 and the thermosyphon heat exchanger that forms the cold heat exchanger 22 that is provided in combination with the liquid nitrogen reservoir 37 is divided has been described. The first heat exchanger 23 is integrated without providing the reservoir 37, liquid nitrogen supplied from the liquid nitrogen supply valve 42 is supplied from the cold end side, and low-temperature high-purity helium gas is supplied to the cold end side. You may make it introduce | transduce from an intermediate part.

The pipes and valves in the path through which the liquid nitrogen and the low temperature helium gas at the liquid nitrogen temperature level flow may be formed as a heat insulating structure or housed in each cold box or the like. Of course, each cold box can be integrated within the size limit.

Further, the liquid nitrogen introduced into the second heat exchangers 25a and 25b is the liquid nitrogen introduced from the liquid nitrogen storage tank 5 through the liquid nitrogen passage 46 without being introduced through the coils 9a and 9b. Alternatively, a proper branching path and valve may be provided for direct introduction.

The large-scale low-temperature gas purifier of the present invention can be applied not only to helium or hydrogen as a gas to be purified but also to a gas having a boiling point lower than that of liquid nitrogen, such as neon, and the liquid nitrogen refrigerant. Since the higher the pressure, the higher the temperature, the pressure of the refrigerant liquid nitrogen is also increased, and if it is set to a temperature higher than the solidification temperature of the gas to be purified, it can be applied to the purification of argon, oxygen, etc. be able to.

[0047]

As described above, according to the large-sized low-temperature gas purifier of the present invention, the consumption of the refrigerant liquid nitrogen for cooling the adsorption column and the introduced gas can be greatly reduced. In addition, by providing the recycle gas circulation path, the helium gas remaining in the adsorption cylinder can be circulated and used as the recycle gas when the process is switched, so that nitrogen as a heating gas is not necessary, and in this respect as well, the consumption of nitrogen is reduced. The amount can be reduced. Further, since the number of times of the displacement vacuum exhaustion after the regeneration can be reduced, the amount of the gas to be purified scattered in the displacement vacuum exhaustion step can be reduced and the vacuum exhaust time can be shortened.

[Brief description of drawings]

FIG. 1 is a system diagram showing an example of an embodiment of a large-sized low-temperature gas purifier of the present invention.

FIG. 2 is a system diagram showing an example of a conventional large-sized low-temperature gas purifier.

[Explanation of symbols]

3a, 3b ... Adsorption cylinder, 5 ... Liquid nitrogen storage tank, 6 ... Evaporator,
8 ... Vacuum pump, 9a, 9b ... Coil, 13a, 13b
... Liquid nitrogen supply valve, 17a, 17b ... Vacuum exhaust valve, 21
... Heat exchange part, 22 ... Cold exchange part, 23 ... First heat exchanger, 24 ... First cold box, 25a, 25b ... Second heat exchanger, 26a ... Second cold box, 26b ...
Third cold box, 27a, 27b ... Purified gas outlet path, 28a, 28b ... Purified gas inlet path, 29a,
29b ... pre-cooling path, 30a, 30b ... pre-cooling valve, 31a,
31b ... Path, 32 ... Blower, 33 ... Heater, 34
Regeneration heat exchanger, 35a, 35b ... Path, 36 ... Regeneration gas circulation path, 37 ... Liquid nitrogen reservoir, 37g, 37i, 3
7o ... path, 38 ... introduction path, 39 ... path, 40 ... valve,
41 ... Path, 42 ... Liquid nitrogen supply valve, 43 ... Low temperature impure gas introduction path, 43a, 43b ... Branch path, 44a, 44
b ... Inlet valve, 45a, 45b ... Path, 46, 46a, 4
6b ... Liquid nitrogen path, 47a, 47b ... Outlet valve, 48 ...
High-purity gas derivation route, 48a, 48b ... Branching route, 49 ...
Return path, 50a, 50b ... Circulation valve, 51a, 51b ...
Adsorption cylinder inlet part, 52 ... Pressure controller (PIC), 53 ... Pressure control valve, 54a, 54b ... Adsorption cylinder heating valve, 55 ... Temperature controller (TIC), 56 ... Circulating gas heating path, 57c,
57d ... Flow path switching valve, 58 ... Nitrogen gas supply valve, 59a,
59b ... Adsorption cylinder outlet, 60 ... Exhaust path, 61a, 61
b ... Adsorption cylinder precooling nitrogen outlet valve, 62a, 62b ... Nitrogen gas exhaust path

Claims (5)

[Claims] 1. A large-sized low-temperature gas purifier for removing impurities in a gas to be purified by low-temperature adsorption, a first heat exchanger for cooling a gas to be purified at room temperature with refrigerant nitrogen, and a plurality of the heat exchangers to be switched to be used. An adsorption column that adsorbs and removes impurities in the purified gas, a coil that cools the adsorption column with refrigerant nitrogen, and a second heat that cools the low-temperature gas to be purified introduced into the adsorption column before the adsorption column with the refrigerant nitrogen. A large-sized low-temperature gas purifier characterized by having an exchanger. 2. The first heat exchanger has a hot heat exchange section and a cold heat exchange section, and the cold heat exchange section circulates liquid nitrogen, which is a refrigerant, by a thermosiphon effect to cool the gas to be purified. The large-sized low-temperature gas purifier according to claim 1. 3. The large-scale low-temperature gas according to claim 1, wherein a precooling path is provided which branches from the purified gas outlet path of the adsorption column and is connected to the purified gas inlet path of another adsorption column. Purifier. 4. A regeneration gas circulation path that branches from the purified gas outlet path of the adsorption column and is connected to the refined gas inlet path of the adsorption column via a blower and a heater is provided. The large-sized low-temperature gas according to any one of claims 1 to 3, further comprising a regeneration heat exchanger that heats the blower inlet side gas and the blower outlet side gas to raise the temperature of the blower inlet side gas. Purifier. 5. The large-sized low-temperature gas purifier according to claim 1, wherein the gas to be purified is helium gas or hydrogen gas.