US3354664A

US3354664A - Transferring condensed liquids to a storage container

Info

Publication number: US3354664A
Application number: US444634A
Authority: US
Inventors: Ster Johannes Van Der; Haarhuis Gerardus Johannes; Tuin Harm Jan
Original assignee: US Philips Corp
Current assignee: US Philips Corp; North American Philips Co Inc
Priority date: 1964-04-11
Filing date: 1965-04-01
Publication date: 1967-11-28
Anticipated expiration: 1984-11-28
Also published as: SE305224B; AT258257B; GB1042130A; ES311630A1; NL6403952A; DE1267690B; BE662342A; NL134862C

Description

Nov. 28, 1967 J. VAN DER STER ETAL 3,

TRANSFERRING CONDENSED LIQUIDS TO A STORAGE CONTAINER 5 Sheets-Sheet 1,

Filed April 1, 1965 TIMER CONTROLLED 3 CbNDENS ATION l SPACE CONDENSATE CONTAINER OR RECEPTACLE GAS REFRIGERATOR STORAGE CONTAINER AGENT ELM/L 8 Nov. 28, 1967 J. VAN DER STER ETAL 3,

I TRANSFERRING CONDENSED LIQUIDS TO A STORAGE CONTAINER Filed April 1, 1965 5 Sheets-Sheet 2 TIMER CONTROLLED 2 3CONDENSATION I SPACE 5 I CONDENSATE CONTAINER 0R 8 1 EcEPTAcLE 4 I 1 sA's REFRIGERATOR OPENED SIMULTANEOUSLY 15 TO DISCHARGE TO CONTAINER STORAGE CONTAINER FIG.3

JOHANNES VAN DEQQTEfi GERARDUS J.HAARHU|S EARN J.TU|N

Nov. 28, 1967 J. VAN DER STER ETAL 3,354,664

TRANSFERRINGCONDENSED LIQUIDS TO A STORAGE CONTAINER Filed April 1, 1965 5 Sheets-Sheei 3 TIM/ER CONTROLLED I CONDENSATION 2 8 3 SPACE CONDENSATE 3 I CONTAINER OR BECEPTACLE 4 2o J t 1 GAS I REFRIGERATOR 8 OPENED SIMULTANEOUSLY CONTAINER 5 1s SLIGHTLY ABOVE THAT IN CONTAINER 7 WHEN PRESSURE IN I STORAGE CONTAINER FIG. 5

res

SHANNES VAN DER w ERN RARDUH. HAARHUI S gA RM .T N

AGEN

Nov. 28, 1967 J. VAN DER STER ETAL 3,354,664

TRANSFERRING CONDENSED LIQUIDS TO A STORAGE CONTAINER Filed April 1, 1965 5 Sheets-Sheet 4 TIMER CONTROLLED R 3 couoiz fi lifiow I 2 SPACE CONDENSATE 1 V 7 5 i CONTAINER OR 3 RECEPTACLE 4% \v 1 GAS I 20 \l 21 REFRIGERATOR 2/.

STORAGE CONTAINER res JOHANN s VAND E GERARDU J-HAARHUIS HARM J.TU|N' BY M K \-R AGENT Nov. 28, 1967 J. VAN DER sTER ETAL 3,354,664

TRANSFERRING CONDENSED LIQUIDS TO A STORAGE CONTAINER Filed April 1, 1965 5 Sheets-Sheet 5 GAS REFRIGERATOR 38 (i 50 49 I GAS LIQUIFIED INLET GAS OUTLET JOHANNES' VAN TOR; GERARDUS J.HAARHUIS H RM J.TUIN

BY v

AGENT United States Patent 3,354,664 TRANSFERRING CONDENSED LIQUIDS T0 A STORAGE CONTAINER Johannes van der Ster, Gerardus Johannes Haarhuis, and Harm Jan Tuin, Emmasingel Eindhoven, Netherlands, assignors to North American Philips Company Inc., New York, N.Y., a corporation of Delaware Filed Apr. 1, 1965, Ser. No. 444,634 Claims priority, application Netherlands, Apr. 11, 1964, 64-3,952 6 Claims. (CI. 62-37) ABSTRACT OF THE DISCLOSURE A method and device for condensing gas for a certain period of time under high pressure in a low temperature device whereupon the inlet is closed and the gas is further cooled down to a temperature corresponding with the vapor pressure which is equal or lower than the pressure prevailing in the liquefied gas storage space.

The invention relates to a method of liquefying a gas and to a device for performing the said method.

In a known method of the present type, a gas under pressure is supplied to a space which is cooled to the condensation temperature of the gas in question associated with that pressure. This space is preferably cooled by means of a cold-gas refrigerator. In that space the gas is condensed, after which this condensed gas is conducted away.

A drawback of this known method, in which gas is continuously condensed and conducted away, is that during the conducting away of the liquefied gas there has to be expanded from the pressure at which the condensation takes place, through an expansion valve to atmospheric pressure. In this case again a great part of the liquid volatilizes which adversely influences the production. The percentage of volatilized liquid may in some cases be even 30% for example, in the case of hydrogen gas which is liquefied under a pressure of 8 atmospheres.

In known devices the volatilized liquid is conducted through a heat exchanger where it is heated again to room temperature in counter current with the gas to be condensed. This gives an improvement of the yield with respect to the above method, but it has the disadvantage that it requires a heat exchanger which in general is com plicated and expensive.

A further drawback of this known type of devices is that the gas to be condensed must be of high purity since otherwise the channels in the heat exchanger and in the expansion valve, which, in general, are very narrow, can be clocked by the contamination-s.

It is the object of the invention to render the above complicated and expensive heat exchanger and the expansion valve superfluous in which all the same the 3,354,664 Patented Nov. 28, 1967 "ice for liquefying gases, for example air, oxygen, nitrogen, hydrogen, helium, etc, with a better yield then could be obtained so far.

A further advantage of the said method is that the condensate is forced into the storage container by the gas under pressure, As a result of this it has become possible to cool the condensate, during the continued cooling, to a very low temperature and pressure and it is even possible to continue the cooling to such an extent that the pressure of the condensate lies below the pressure in the storage container while all the same the transport of the condensate to the container can take place in a comparatively short period of time. This will be further explained in the description of the figures.

The invention further relates to a device which is suitable for performing the method according to the invention. This device is particularly suitable for heavier gases, for example, oxygen and nitrogen. The device according to the invention comprises at least one refrigerator, the cold part of which is arranged in a condensation space to which space are connected an inlet pipe for gas under pressure and an outlet pipe for liquefied gas. This device is characterized in that in the inlet and outlet pipes controllable cocks are provided in which in the outlet pipe also a check valve is operative which checks the flow out of the storage container to the condensation space, the device comprising a control device, which, when the cock in the outlet pipe is closed, keeps the cock in the inlet pipe opened for a given period of time or after a given quantity of condensate is present in the device, after which the control device closes the cock in the inlet pipe and the refrigerator reduces the pressure of the condensate by continued cooling until this pressure is lower than the pressure in the storage container, after which the control device opens the cooks in the inlet and outlet pipes.

So in this case the condensate enters the storage container in a supercooled condition. This has the advantage that the losses of insulation which always occur cause no evaporation of condensate. Consequently little or no vapour is blown olf out of the storage container so that substantially no gas loss occurs.

The expression supercooled condition of the condensate is understood to mean in the present application that the temperature of this condensate is lower than the boiling point temperature of the condensate at the pressure prevailing in the storage container.

A difiiculty in this device is that during forcing the condensate out of the condensation space to the storage container the possibility exists that simultaneously with the last quantity of condensate also a quantity of gas under high pressure disappears to the storage container and from there is blown off and is to be considered as a loss.

favorable condition of liquefying gas under high pressure is maintained which consequently can take place at a higher temperature, at which temperature the required cold can in general be supplied more efiiciently.

The method according to the invention is characterized The method according to the invention may be used In order to overcome this difliculty a further embodiment of the device according to the invention is characterized in that the outlet pipe empties at a low point in the condensation space and that opposite to the outlet a float is arranged which is capable of closing this outlet when the liquid has fallen below a given level.

It has been found possible to use a float for these heavier gases. This float ensures that, when the liquid level has fallen below a given value, the outlet of the liquid outlet pipe is closed so that the gas under pressure can no longer flow to the storage container. As a result of this losses of gas, which often is expensive, is prevented.

A further favorable embodiment of the device according to the invention is characterized in that the float has thin walls and comprises a pipe which is open at both ends, one end of the said pipe emptying substantially at the bottom of the hollow float and the other end extend- ,ng upwards through such a distance that the upper end always projects above the liquid in the condensation space. Therefore in this device the same pressure will prevail in the float and in the condensation space, so that the walls of the float are not subjected to high pressure- ;litferences. As a result of this, the walls of the float may be thin so that it has a light-weight construction and a comparatively small float will be suificient. A further advantage of this construction is that, when condensate collects in the float, this condensate is pumped back again to the condensation space through the open pipe out of the float during the period that the pressure in the condensation space is being reduced.

In the case of liquefied gases, for example, hydrogen and helium, which have a very low specific weight, it is no longer practical to use a float of reasonable proportions. In order to condense these valuable gases also with the method according to the invention without great losses occuring because an inadmissable quantity of these valuable gases disappears to the storage container with the last condensate, a favorable embodiment of the method in accordance with the invention is characterized in that controllable cocks are provided in the inlet and outlet pipes, and a check valve being provided, if desired, in the outlet pipe. The controllable cock itself operating as a check valve, if desired, which prevents flow of medium from the storage container to the condensation space, a circulating pipe being connected in parallel with the cock in the inlet pipe, in which circulating pipe a flow resistance and a further controllable cock are provided, which flow resistance has such a passage that the stream of gas flowing through it at the full pressure difference between the gas inlet pipe and the storage container substantially corresponds to the gas current which the coldgas refrigerator can condense at a pressure which is substantially equal to the pressure in the storage container. The present device comprising a control device which, when the cock in the outlet pipe is closed, keeps the cock in the inlet pipe opened for a given period of time or until a given quantity of condensate is present in the device, after which the control device closes the cock in the inlet pipe and the refrigerator reduces the pressure of the condensate by continued cooling until said pressure lies somewhat above the pressure in the storage container, after which the control device opens the cock in the outlet pipe and the further cock. Although this device comprises no float, it has all the same been prevented that an inadmissible quantity of these valuable gases is lost. The operation and advantages of this device will be further explained in the description of the figures.

A further favorable embodiment of the above device according to the invention is characterized in that in the circulating pipe between the flow resistance and the further cock a further container is provided, the control device opening the cock in the outlet pipe and the further cock in the circulating pipe only when the pressure in the condensation space is lower than the pressure in the storage container. Therefore in this case there is the possibility of supercooling the liquid.

In order that the invention may readily be carried into effect, a few devices for liquefying gases will now be described in greater detail with reference tothe diagrammatic drawings in which FIG.-1 diagrammatically shows a device for liquefying gases;

FIG. 2 shows the operation of the device shown in FIG. 1 in a pressure-time diagram;

FIG. 3 shows a device for liquefying heavier gases;

FIG. 4 shows the operation of the device shown in FIG. 3 in a pressure-time diagram;

FIGS. 5 to 8 show two devices for liquefying lighter gases, for example, hydrogen and helium, with the associated pressure-time diagram in which the operation of these devices is explained;

' 4 FIG. 9 shows a further embodiment of a device for liquefying gases.

In FIG. 1, reference numeral 1 denotes a container which contains gas under high pressure. This container is connected, through a gas inlet pipe 2, to the condensation space 3 around the head of a cold-gas refrigerator 4. The condensation space 8 is in open communication with a container 5 which consequently also forms part of the condensation space. If desired, the condensate may naturally also be stored in the space 3 itself. The container 5 is provided with an outlet pipe 6 for condensate which empties in a storage container 7. In the gas inlet pipe 2 a cock 8 is provided, while the .outlet pipe 6- for condensate comprises a cock -9..The cocks-8 and 9 are operated by a control device which in accordance with the pressure in the container 5 or, if desired, in accordance with time, opens or

closesthe cocks

8 and 9. The operation of this device will be explained with reference to the time-pressure diagram shown in FIG. 2. The container 1 contains a gas, for example, air, oxygen or nitrogen, under a pressure p which, for example, is from 5 to 6 atmospheres. While the cock 9 is closed, the cock 8' is opened. In the

spaces

3 and 5 gas enters under high pressure. This high-pressure gas condenses on the cold head of the coldgas refrigerator, the condensate being received in the container 5. After a given period of time, or when a given quantity of condensate is available in the container 5, the cock 8 is closed. This consequently happens at point 10 in the diagram of FIG. 2. The cold-gas refrigerator 4 goes on supplying cold, gas condensing on the cold head of the machine from the

spaces

3 and 5. The temperature in these spaces gradually decreases .while the pressure also decreases. In FIG. 2 the pressure variation is plotted against time by the sloping line from point 10. When as a result of the continued cooling the pressure in the

spaces

3 and 5 has fallen to the pressure p the cock 9 is opened and the condensate can flow into the storage container 7. The pressure p must be chosen to be sufliciently high above the container pressure so as to retain a' suflicient excessive pressure for forcing the liquid out of the container 5 into the container 7. This means that the cooling in the containers3 and Smay not be continued to such an extent as would be desirable. First .of all, when opening the head 3, the condensate will expand to the head pressure in which again part of the condensate evaporates. Secondly, part of the liquid stored in the container 7 will .evaporate by penetrating heat and disappear through a blow-off into the atmosphere which consequently means a loss. In order to restrict this loss one would introduce the liquid in the supercooled condition into the container 7, if this were possible. In that case, the liquid in the container 7 would be heated to substantially its boiling point temperature by the penetrating heat. This consequently means that already so much cold is introduced in the head 3-and container 5 that therewith the insulation losses of the container 7 are overcome. When in the device shown in FIG. 1 the condensate is to be transferred from the container 5 to the container 7 within a permissible period of time, the pressure 11 must be chosen to be rather high before the removal of the liquid-begins. After the liquid has been transferred from the container 5 into the container 7, the cock 9 is closed and the cock 8 is opened and the pressure in the head 3 and container 5 again increases to the starting pressure p at which point the condensation mainly takes place.

According to the invention, the continued cooling may be continued to a pressure which is substantially equal to the pressure in the container 7 or even to a pressure which lies below the pressure in the container 7, while in addition the time for transferring the condensate from the container 5 to the container 7 is considerably shortened. In the devices .according to the invention both

cocks

8 and 9 are opened for that purpose during the transfer of the condensate from the container 5 to the container 7, so that the liquid is forced by the gas under high pressure from the container 5 into the container 7. First of all this is performed very rapidly and, secondly, supercooled liquid may beforced into the container 7.

FIG. 3 shows a device for liquefying heavier gases, for example, air, oxygen and nitrogen. This device again comprises a container 1 for gas under high pressure, which container is connected through an inlet pipe 2, to the condensation space 3 and the container 5. The container 5 is connected to the storage container 7 through an outlet pipe 6. The inlet pipe 2 comprises a cock 8. The outlet pipe 6 comprises a check valve 15 in addition to a cock 9. The functions of the cock 9' and the check valve 15 may be combined, if desired, in a magneticallyoperated valve which operates in the direction of the container 5 as a check valve and can be lifted electromagnetically from its seating.

The operation of the device shown in FIG. 3 is shown in the time-pressure diagram of FIG. 4. When the cock 9 in the outlet pipe 6 is closed, the cock 8 in the inlet pipe 2 is opened. As a result of this, gas under a pressure p can enter the condensation spaces 3 and 5-. At this pressure p the cold-gas refrigerator 4 condenses this gas under high pressure for a given period of time. After a given period of time or when a given quantity of condensate is collected in the container 5, the cock '8 is closed. The cold-gas refrigerator 4 continues its cold production, the pressure and the temperature in the

spaces

3 and 5 gradually reducing. The pressure in this case follows the line 16, 17 in the diagram of FIG. 4. The continued cooling lasts until the pressure in the

spaces

3 and 5 is equal to a pressure p which is lower than the pressure prevailing in the storage container 7. At that instant a quantity of condensate is contained in the continer 5 at a pressure and a temperature of the condensate which are bothlower than the pressure and the temperature of the condensate which is already in the storage container 7. After the pressure p has been reached, the cocks 9 and '8 are both opened substantially simultaneously. As a result of this, the pressure in the

spaces

3 and 5 rapidly increases. When the pressure in the space 5 is equal to the pressure in the container 7, the transport of condensate to the container 7 begins. This is indicated in the diagram by the point 18. Now the condensate is' powerfully forced out of the space 5 into the space 7 by the gas under high pressure so that the transport takes place very rapidly and consumes little time. The possibility exists that simultaneously with the last of the condensate which flows to the container 7 also part of the gas under high pressure flows to the container 7 and then through the blow-off aperture into the atmosphere which would mean a loss. In order to prevent this, a float is provided opposite to the aperture of the outlet pipe 6 in the container 5 which closes the aperture of the outlet pipe 6 as soon as the liquid level in the container 5 has fallen below a given value. This float is not shown in the diagrammatic drawing of FIG. 3 but is visible in the device shown in FIG. 9.

Since in the case of lighter-weight gases, for example, hydrogen and helium, no float of permissible proportions can be used any longer, the device shown in FIG. 3 is not particularly suitable for this type of gas. When as a matter of fact no float' is available, always part of these valuable gases will flow to the container 7 .at the end of the forcing-out period of the condensate and be conducted away, which means a loss. In FIG. 5 a device is shown for liquefying light gases in which this loss will not occur or will occur only to a smallextent. In this figure corresponding component parts are given the same reference numerals as in FIG. 3. The only difference with the device shown in FIG. 3 is that the inlet pipe 2'is provided with a circulating pipe 19 in which a flow resistance 20 constructed as a capillary and a further cock 21 are provided.

'The operation of the device shown in FIG. 5 is shown in the time-pressure diagram of FIG. 6. When the cock 9 in the outlet pipe 6 is closed, the cock 8 in the inlet pipe 2 is opened. As a result of this high-pressure gas can again enter the

condensation spaces

3 and 5 out of the container 1. The cold-gas refrigerator 4 condenses a quantity of gas for a given period of time. Then the cock 8 is closed while the cold-gas refrigerator continues the supply of cold. As a result of this the pressure in the spaces 3' and 5 decreases according to the line 22-23. At point 23 the pressure has decreased to just above the pressure which prevails in the container 7. At that instant both the cocks 9 in the outlet pipe 6 and the further cock 21 in the circulating pipe 19 are opened. The capillary 20 is constructed so that through it a quantity of gas per unit of time can flow which substantially corresponds to the quantity of gas which the cold-gas refrigerator can condense per unit of time.

This consequently means that by opening the cock 21 the pressure in the container 5 remains substantially equal. So the condensate is forced out of the container 5 at equal pressure. When the condensate has disappeared from the container 5 the pressure in this container will decrease for a moment to the pressure in the container 7, a small quantity of gas flowing through the container 7'. Then the control device closes the cock 9 in the outlet pipe 6 as well as the further cock 21, while the cock 8 in the inlet pipe for medium is opened again and the pressure in the

spaces

3 and 5 increases rapidly to the pressure p at which condensation substantially takes place.

In this device it is not necessary to have a check valve 15 in the outlet pipe 6 for condensate, because the pressure in the container 7 is always somewhat lower than the pressure in the container 5. However, to be quite on the safe side it is possible to have a check valve in the outlet pipe 6 for the medium.

Instead of the capillary .20, a needle valve may also be used as a flow resistance. In such a valve a very narrow passage may be. adjusted.

A drawback of the device shown in FIG. 5 is that during the continued cooling the pressure cannot be reduced further than the pressure which corresponds to the point 23 of FIG. 6. So in this case no supercooled liquid can be forced into the container 7. In this device, consequently, a certain loss of gas will occur because as a result of insulation losses a quantity of the condensate evaporates in the container 7. This drawback is avoided in the device shown in FIG. 7. In this device, an auxiliary container 24 is provided in the circulating pipe 19 between the capillary 20 and the further cock 21. In addition, this device requires a check valve 15 in the outlet pipe 6. The operation of this device follows from the diagram shown in FIG. 8. First, again the cock 8 is opened, as a result of which gas under a pressure p can enter the

condensation spaces

3 and 5 and be condensed there under high pressure. Then the cock 8 is closed and the pressure is reduced, under continued cooling by means of the coldgas refrigerator 4, to a pressure which-corresponds to point 25 shown in FIG. 8. The pressure at point 25 is lower than the pressure which prevails in the container 7. After this pressure has been reached, the cock 9 in the outlet pipe 6 is opened, while substantially simultaneously the further cock 21 in the circulating pipe 19 is opened. As a result of this, the auxiliary container 24 is connected to the

condensation spaces

3 and 5. The gas of high pressure in the auxiliary container 24 now enters the

spaces

3 and 5. As a result of this the pressure in the

spaces

3 and 5 rapidly increases to a pressure which .corresponds to point 26 in the diagram of FIG. 8. Thus, this pressure lies somewhat above the pressure in the container 7 so that with this pressure the supercooled liquid can be forced out of the container 5 into the container 7. So now supercooled liquid is transferred to the container 7 in which liquid so much cold is present that the insulation losses of the container 7 are greatly obviated. After removing the remainder of the condensate, a small quantity of gas will flow to the container 7, while the presare in the container decreases. Then the cock 9 in the utlet pipe 6 is closed and the cock 8 in the inlet pipe i opened again after which the pressure again rapidly inreases to the value p and condensation at this high presure can take place again.

FIG. 9 shows a device for condensing air, nitrogen or xygen; This device comprises an inlet pipe for gas to e condensed, which pipe comprises a cock 31. The inlet -ipe 30 is connected to an insulated space 32. In this space lhich is surrounded by the insulating jacket 33, a number if snow separators 34 are arranged around a container '5. The snow-separators 34 may be constructed in accord- .nce with the separators described in French patent speciication 133,695 (Dutch patent specification 269,432). The eparators 34 are connected to the container 35 which, at ts upper side, is connected, through a gas inlet pipe 36, o the condensation space 37 around the cold head of the zold-gas refrigerator 38. The condensation space 37 is irovided with an outlet pipe for condensate 62, the upper :nd of which is connected to a container formed by the vall 39 in the container 35. This container 40 is in a communicating connection with the separator 34. An overlow pipe 60 for conducting away condensate to the con- :ainer 51 is connected to the container 40. Below the bot :om the walls of the container 35 extend as a perforated iheath-like wall 41. This wall is provided with a bottom 12 in which a liquid outlet pipe 43 is connected. This .iquid outlet pipe 43 extends through the container 35 upwards and disappears through the insulation wall 33 to a storage container not shown. The bottom 42 further comprises a number of pipes 44 between which a float 45 is arranged. This float comprises a ball 46 which, when the liquid falls too low, can close the aperture of the liquid outlet pipe 43. The float is provided with a pipe 47 which is open at both ends. With its one end, this pipe empties at the bottom of the float, while the other end projects upwards so that this end always projects above the liquid in the container. As a result of this, the pressure inside and outside the float will always be equal so that across the wall of the float no large pressure differences will prevail. As a result of this, the float need not be of a particularly heavy construction. Inside the insulati-on wall 33 a wall 48 is provided which separates the space, in which the separators 34 are arranged, from the space in which the condensated liquid is received. So in this device there is available an extensive shallow liquid bath 51, which is desirable in connection with the continued cooling in which the liquid is cooled by boiling and the vapour formed is then condensed again on the cold head of the cold-gas refrigerator 38.

The operation of this device is as follows: When the cock 31 in the inlet pipe 30 for medium is opened, gas under high pressure enters the space 32 and thence flows to the space 35 through the layers of gauze of the separators 34. This is indicated by the arrows p. Since the gauze of the separators 34 is strongly cooled by gas which is already condensed in the pipes of the separators, the contaminations which may possibly be in the gas, will be frozen out on this gauze. The gas entering the space 35 is drawn into this space through pipe 36 by the subambient pressure which prevails in the condensation space 37. The gas condensed in the condensation space 37 can flow back to the space 40 through the pipe 62. The condensate is first received in the space 40 until a level has formed which reaches as high as the overflow pipe 60. When the supply of condensate is continued, part of this condensate will disappear into the liquid space 51 through the overflow pipe. In the container 40 consequently always a given quantity of condensate is available. Since this container is connected to the cooling channels of the separators 34, condensate also will be present in these channels. As a result of the supply of heat, a vapourbubble pumping effect will occur in these channels as a result of which the condensate is pumped upwards through the channels. In this manner a satisfactory even cooling of the gauze layers on which the contaminations are frozen out is obtained. After a given period of time'the cock 31 is closed and the cold-gas refrigerator reduces by continued cooling the pressure and consequently also the temperature in the space and thereby also that of the condensate. This cooling is continued until the pressure of the condensate is below the pressure which prevails in the storage container so that liquid is obtained which, with respect to the pressure which prevails in the storage container, is subcooled. Then, simultaneously, the

cocks

49 and 31 are opened, as a result of which the pressure in the space 35 above the liquid rapidly increases to a value which lies considerably above the pressure which prevails in the storage container. As a result of this high pressure, the liquid is powerfully forced into the liquid outlet pipe 43. As a result of this a very rapid siphoning over of liquid to the liquid container takes place. So the coldgas refrigerator condenses at the lower pressure only for a comparatively short period of time. When the liquid in the container 51 falls below a given level, the float will close the liquid outlet pipe 43 at a given instant so that it is prevented that high-pressure gas disappears to the storage container with the last liquid.

The above device may be used for liquefying helium or hydrogen in addition to air, nitrogen and oxygen. In that case, only the gas inlet pipe must be provided with a circulating pipe parallel to the cook 31 as described in the device shown in FIGS. 5 and 7. The control must then be effected as is described in FIGS. 6 and 8.

With the method and device according to the invention it has become possible to liquefy gases with a good yield and to transfer them to a storage container.

What is claimed is:

p 1. An apparatus for liquefying gas supplied under pressure to a receptacle which is cooled to the condensation temperature of the selected gas comprising a cold source for cooling said receptacle whereby said gas is condensed, an inlet pipe for said gas supply under pressure, an outlet pipe for said liquefied gas, acont-rollable valve in each of said inlet and outlet pipes, a storage container, and a control device which when the valve in said outlet pipe is closed maintains the valve in the inlet pipe open for a predetermined period of time, said control device thereafter closing said valve in the inlet pipe, said cold source continuing to cool said receptacle and reducing the pressure of said condensate until said pressure is lower than the pressure in said storage container, and thereafter said control device opening said valves in said inlet and outlet pipes when the pressure in the receptacle is at the said lower pressure whereby the condensate is forced into said storage container by said gas under pressure.

2. An apparatus as claimed in claim 1 wherein said outlet pipe is connected at one end into said receptacle at a low point thereof, said one end being directed upwards, and a float being located adjacent to the opening which when said liquid has fallen below a given level closes said aperture.

3. An apparatus as claimed in claim 2 wherein the walls of said float are of a relatively thin construction, a pipe connected to said float and open at both ends, one end of said pipe emptying at the bottom of said float and extending upwards from said float so that the upper end always projects above the liquid in the condensation space of said receptacle.

4. An apparatus for liquefying gas supplied under pressure to a receptacle which is cooled to the condensation temperature of the selected gas comprising a refrigerator, the cold part of said refrigerator being connected to the condensation space in said receptacle, an inlet pipe for said gas under pressure connected to said receptacle, an outlet pipe for said liquefied gas connected to said receptacle, controllable valves in both said inlet and outlet pipes, a storage container for said liquefied gas, a circulating pipe in said inlet pipe line bypassing the controllable valve therein and having a flow resistance and an additional controllable valve therein, said flow resistance being so constructed that the gases passing through it at the full pressure difl'erence between said gas inlet pipe and said storage container substantially corresponds to the flow of gas which said refrigerator condenses at a pressure which is substantially equal to the pressure in said storage container, and a control device which when the valve in the outlet pipe is closed maintains the valve in the inlet pipe open for a given period of time, said control device thereafter closing said valve in the inlet pipe and by continued cooling of said refrigerator the pressure of the condensate is decreased until it is slightly above the pressure in said storage container, and subsequently said control device opening the valve in said outlet pipe and said additional controllable valve when the pressure in the receptacle is at the pressure slightly above the pressure in the storage container.

5. An apparatus as claimed in claim 4 wherein between said flow resistance and said additional controllable valve a further container is located, said control device opening said valve in said outlet pipe and said additional controllable valve in said circulating pipe only when the pressure in said condensation space is lower than the pressure in said storage container.

6. An apparatus as claimed in claim 4 wherein said flow resistance is a capillary.

References Cited UNITED STATES PATENTS 3,210,952 10/1965 St-rorn 62-40 3,282,061 11/1966 Van Geuns 6Z37' NORMAN YUDKOFF, Primary Examiner.

V. W. PRETKA, Assistant Examiner.

Claims

1. AN APPARATUS FOR LIQUEFYING GAS SUPPLIED UNDER PRESSURE TO A RECEPTACLE WHICH IS COOLED TO THE CONDENSATION TEMPERATURE OF THE SELECTED GAS COMPRISING A COLD SOURCE FOR COOLING SAID RECEPTACLE WHEREBY SAID GAS IS CONDENSED, AN INLET PIPE FOR SAID GAS SUPPLY UNDER PRESSURE, AN OUTLET PIPE FOR SAID LIQUEFIED GAS, A CONTROLLABLE VALVE IN EACH OF SAID INLET AND OUTLET PIPES, A STORAGE CONTAINER, AND A CONTROL DEVICE WHICH WHEN THE VALVE IN SAID OUTLET PIPE IS CLOSED MAINTAINS THE VALVE IN THE INLET PIPE OPEN FOR A PREDETERMINED PERIOD OF TIME, SAID CONTROL DEVICE THEREAFTER CLOSING SAID VALVE IN THE INLET PIPE, SAID COLD SOURCE CONTINUING TO COOL SAID RECEPTACLE AND REDUCING THE PRESSURE OF SAID CONDENSATE UNTIL SAID PRESSURE IS LOWER THAN THE PRESSURE IN SAID STORAGE CONTAINER, AND THEREAFTER SAID CONTROL DEVICE OPENING SAID VALVES IN SAID INLET AND OUTLET PIPES WHEN THE PRESSURE IN THE RECEPTACLE IS AT THE SAID LOWER PRESSURE WHEREBY THE CONDENSATE IS FORCED INTO SAID STORAGE CONTAINER BY SAID GAS UNDER PRESSURE.