US1119159A - Apparatus for separating liquid air into its constituents. - Google Patents

Description

G. HILD'EBRANDT. APPARATUS FOE. SBPARATING LIQUID AIR INTO ITS OONSTITUENTS.

APPLIGATIQN FILED SBPT.26, 1913.

' Patented Dec. 1, 1914;

4 SHEETS-SHEET 2.

j I w'mvglioz moan,

' G. HILDEBRANDT. APPARATUS FOR SEPARATING LIQUID AIR INTO ITS GONSTITUENTS.

APPLICATION FILED SEPT. 26. 19131 Patented Dec. 1. 1914.

4 SHEETS-SHEET 3.

fm @51 mtozmuf ,G. HILDEBRANDT. APPARATUS FOR SBPA'RATING LIQUID AIR INTO ITS GONSTITUBNTS.

Patented Dec. 1, 1914.

7 APPLICATION FILED SEPT. 26, 1913. 1 1 1 9,1 59;

a m w n 5 UNITED snxrrnsrarrnnr OFFICE.

GOTTHOLD HILDEBRANDT, OF BERLIN, GERMANY, ASSIGNOR TO AMERICAN INDUS- TRIAL GAS COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

APPARATUS FOR SEPARATING LIQUID AIR INTO ITS CONSTITUENTS.

Patented Dec. 1, 1914.

(riginal application fl1ed.0ctober 16, 1912, Serial No. 725.988. Divided and this application filed September useful improvements in apparatus for liquefying air and separating the same into its constituents.

This application is filed as a division of my prior application, Serial No. 725,988, filed October 16, 1912, and as a continuation in part of my prior application Serial No. 627,549 filed May H3, 1911.

The invention consists in the apparatus to be more fully described hereinafter and the novelty of which will be particularly pointed out and distinctly claimed.

I have fully and clearly illustrated my invention in the accompanying drawings to be taken as a part of this specification, and wherein- Figure 1 is a view in elevation of the exterior of an apparatus embodyingmy. in-' vention. Fig. 2 is an internal View of the apparatus substantially on the line 2-2 of Fig. 4, the parts being in elevation and certain parts being developed into the same plans for clearness and simplificationof the showing, parts being broken awav and other parts being in section. Fig. 3 is an on larged detailed sectional View. Fig. 4 is a top plan view of the apparatus with the cover removed. Fig. 5 1s a sectional view on the line of Fig. 3. I

Referring to the drawings by characters of reference, 1 designates a casing of any suitable construction, Within which is inclosed the apparatus and elements for performing the liquefaction and separating functions as will be more fully set forth hereinafter. This apparatus, while capable of wide variation without departing from the intended scope of my invention, is shown in this application in what appears to me at this time to be its preferred embodiment, said apparatus consisting of vertical supports each consisting of a: pair of spaced members 2, 2, resting at their lower ends on the base of the casing 1, said'rnembers 2,2, of each pair being spaced by spacing blocks, 3, 4, at the upper and lower endslrespectively of said members.

Serial No. 791,964.

preferably of lead, the-upper end of which is closed. Arranged within the pipe 5 is a plural ty of small conduits or tubes 6, shown as six in number, to conduct compressed air to the apparatus, said pi es bein coiled within the pipe 5 and fol owing t e same throughout 1t's length. These pipes or tubes 6 are preferably made of copper, and are each supported in contact with the inner surface of the pipe 5, for a purpose to be more fully set forth hereinafter. The tubes 6 emerge through the .upper closed end of the pipe 5 and are connected by a reducing coupling or nipple 7 to an inlet pipe 8, the latter p1 e being connected to any suitable source 0 air or gas under pressure, such for instance as an air compressor. The connection between the pipe 8 and the tubes 6 is such that air or gas flowing through said pipe 8 enters the small tubes but does not enter the free space in the bore of the pipe 5 which surrounds said tubes. I do not limit myself to the length of pipe 5, or to its diameter, or to the number of tubes 6 contained therein, as these may be varied'according to the size or capacity of the installation, nor do I limit myself to the material of which the pipe and tubes are made.

The pipe 5 1S closed at its lower end, through which closed. end the tubes 6 emerge and are connected by a reduction nipple or' coupling 9 to a pipe 10 so that the compressed air which enters the said tubes at the coupling 7 will emerge from said tubes at v 11 and is then carried up through the same I and through a cylinder 14 extending vertically and centrally, through a vertical cylinder15 mounted on the upper end or forming a continuation of the receptacle 11. This cylinder or shell. 15, which is imperforate, is of such a length as to extend from a point below the outlet end of the counter-current coil to a point just below the upper end of said coil, said cylinder being closed at its upper and lower ends by heads 16, .17, re-

chamber will be set forth presentl spectively, the head 16 being imperforate and the head 17 being perforated as at 18 see Fig. 3) for a purpose to be resently set orth. At its upper end, the s ell 15 supports a chamber 19, having its upper end closed by a head 20,. the purpose of which The column 14 which is closed at its lower end .extends through and above the head 16 of the cylinder 15, and carries and communicates with an expansion chamber 21, the upper end of w ich engages and is closed by the head 20: 21 is preferably concentric with the chamber 19 and contains an expansion valve 22 1 ofan suitable constructionto the casing of which the pipe 13 is connected, said valve controlling. the outlet from said pi e. The expansion valve is regulated by t e hand wheel 23 and shaft 24, the wheel being located outside the casing. The expansion valve is surrounded by a splasher cone 22 by means of which the expanded and 1i uefied air. is deflected down into the cy inder 14. 1

The chamber or receptacle 11, column 15 andchamber 19 may be supported in any lower suitable manner, as by upper and of the brackets 25, 26, engaging the head chamber 19 and the receptacle 11, as shown in Figs. 2 and 3 of the drawings.

Located within the cylinder 14 and extending from a point above the partition 16 to a point above the bottom of said cylinder is a plurality ofv'ertically disposed ipes 27, perforated at their lower ends as at 28, and provided at their upper ends respectively with outlet branches 29 extending through the wall of the cylinder 14 and opening over the head 16, each branch having an opening 29 in its lower side. By the arrangement of the pipe 13, expansion valve 22, cylinder 14, and pipes 27 it will be seenthat the liquid air will pass down the cylinder 14 and surround the pipe 13, and and then pass up in the tubes that all of the pipes will be uniformly heated, as will appear hereinafter. The

' lower ends 32 of the pipe coils '31 extend through the bottom head 17 of the shell 15 andopen into the receptacle 11 occupied by the heating coil 12 heretofore described and are normally sealed by the li uid in said receptacle. These pipes or coils 31 are preferably of copper and are The said chamber- Lumen ber 19 to the receptacle 11, as will be more the description of the I fully set forth in process and operation. These p1 es 31 constitute what is in effect a recti cationjcolumn, the function of which is to separate the liquid air flowing therein into its constituents. The'pipes or eoils 31 are prefer; abl of copper and imperforate throughout then length, althou h they may be made porous material i desired.

Gommunication is established between the space outside the coils 31 and the chamber 9 b means-of escape ducts 31", of such a heig t as to have their u per open ends located above the level 0 any body of liquid air which may be supported on the late 16, so that ases may-emerge thererom but the liquid will not enter the same. 33 designates a .dome or bell arranged centrally by the heating coil 12, said dome or bell having a perforated top or cap 34, and passages 35 at its bottom edge where it rests upon the floor of the receptacle 11. Within this dome or bell 33, is a closed top column 38, having an opening 37 at its bottom portion, and within which column 36, extends the open end of a pi e 38, which pipe extends from the interior of the column adjacent the top thereof outthrough the bottom of the receptacle 11 and into the closed end of the lead pipe '5 of the primary counter-currents apparatus, and through the latter, emergin' therefrom at 39 and opening out throug the casing at 40, said pipe 38 serving as the outlet for the oxygen from the apparatus. The column 36 prevents the vaporized oxygen from entering the pipe 38.

Connected to the upper end of the chamber 19 is'an outlet pipe 41 which extends down alongside the cylinder 15, and is connected at its lower end to the counter-current pipe 5 so that nitrogen from the chamber 19 will pass to the counter-current conduit 5, and then flow up therethrough to the last turn of the coil where a branch pipe 42 is provided by means ofwhich the nitrogen passes off from the apparatus.

43 designates a pipe coil located in the chamber 19 and surroundin the chamber 21, said coil having one en opening into the chamber 21 and the other end opening into the chamber 19. This pipe coil 43 serves an important function inthat little drops that are carriedby the gas stream, will pass into said coil and form there big drops and then be conveyed to plate 16 together with the other liquid. A pipe 21 maybe used to convey liquid air from the expansion valve when the liquid air is not to be rectified into its constituents.

of the receptacle 11 and surrounded apparatus a suitable pipe such .as may be provided leading from the lower portion or other suitable portion of the apparatus to a pressure gage 51. Similarly p1pes52 and 58 may be provided leading from different levels to a suitable gage 54. By means of test cocks and 56 arranged at different levels the nature of the products in different parts of-the apparatus can be tested. The test cock 55 has been developed tubes 6 of the counter-current apparatus, the

air entering at a temperature of approximately 15 degrees (3., a pressure which may be e. 5O atmospheres, or even a much higher prcss1.u'e,'c. 9., 150 or 250 atmospheres. The air then flows down through said tubes 6 to the coil 12 located in the chamber 11, whcuceit flows by the pipe 13 up through the shell 14 and is released from the expansion valve into the chamber 21 where the pressure is substantially atmospheric, or slightly therebclow, e. g., 0.3 to 0.5 atmosphere. he release and expanslon of the air cause a reduction in its temperatureaccording to the well known principle thatair under pressure when released fromv a space of high pressure into a space of low pressure will have its temperature reduced;

and results in liquefying a considerable por tion of the air. The liquid air thus formed flows into the column 14 and as the level rises therein, said liquid air will enter the openings 28 and pass up through the pipes 27 the head 16 which serves as a and and from the branch pipes 29 onto distributing tubes'3l of liquidair flows down the coiled tubes 31 toward the chamber or receptacle 11. In this chamber 11 theliquid air is'heated by means of the coil 12 and is partly evaporated, part of the heated products of evaporation passing up through the plate 17 and flowing through the spaces between the pipes 31 beats the said pipes, thereby causing the descending liquid air in said pipes 31 to be separated or rectified into nitrogen and oxygen, theair becoming richer in oxygen as it approaches the lower ends of the tubes until almost pure liquid oxygen emerges from the lower ends of said tubes. The liquid oxygen flowing from the tubes 31, together with the liquid in the chamber 11 into which the ends of these tubes dip, forms aliquid seal for the ends of the tubes and thus the entrance of IHCOmIIIg compressed air in said I rent apparatus,

oxygen vapors 'into the tubes to any considerable extent is revented. The nitro en gases flow from t e upper ends offthe tu into the chamber 19 and from this chamber the flow through the pipe'41 to the lower en of the counter-current ipe5 which they enter, andflowing through the same about the pipes 6, reduces the temperature of the pi es so that the same is in efi'ect refri era'ted efore being admitted to the pi e 13 eading to the expansion valve 22. he liquid oxygen which usually fills the receptacle 11 to a height of e. 9., 6 to 8 centimeters flows from this receptacle through the ipe 38 extend-. ing through the pipe 5 of t e counter-curin which pipe it is vaporized and the vapors together withthe unvaporized liquid oxygen serve to reduce the'tcmperaturc ot the incoming compressed air.

In the normal operation of the apparatus after the liquefaction of the compressed air has started, and the nitrogen and oxygen have started to flow through the pipe 5 and the tube 38, the entering compressed air is cooled in the counter-current coil 5 to approximately -135 degrees 0., and thisair is further cooled in passing through the coil 12 in the receptacle 11, said coil being surrounded by boiling oxygen, the temperature of which is approximately -183 degrees C. The air in ascending the pipe 13, and being expanded from the valve22, is more or less completely liquefied the temperature after expansion being about -196 degrees C. The air at this temperature, that is 196 degrees C., flows into'the column' 141 and the pipes 28 and thence into the coils 31 where, by the ascending gases from the receptacle 11 it is warmed up to about .183 degrees (3.,at 'which'temperature it enters to receptacle '11. .In this receptacle the coil 12 introduces enough heat to evaporatepar't of the liquid oxygen, the products of evaporation passing through the column 15.

The dome 33 serves to deflect the liquid discharged from the tubes 31 onto the coil 12, so that the main heating and vaporizing of the liquid is effected outside this dome fwhile the liquid Within it is protected from the coil and kept in a relatively quiescent. condition. this dome escapes through its perforated top.

It will be seen that the apparatus, as illustrated and described, includes a primary counter-current apparatus comprising the coil 5, containing the compressed air pipes 6 and the oxygen pipe 38. During the operation of the apparatus the compressed air flows down the pipes 6 entering the same at approximately 15 degrees C. at a pressure of e. g. 50 atmospheres while the nitrogen flows up through the free space and escapes Any oxygen vaporized within 7 through the expansion valve together with unliquefied air at atmosphere rise in temperature being caused by the la-.

its pressure is mixture and of causlng a at approximate] 10 C. and a pressure of about 1 atmosp ere. The liquid oxygen leaving the chamber 11 by the pipe 38 is vaporized .and warmed in. its passage through this pipe, and also leaves the countercurrent 001]. at a temperature of about 10? C. and a pressure of :1 out 1 atmosphere. The result of the heat interchange which goes on in this counter-current apparatus is accordingly to reduce the temperature of the in-flowing compressed air to approximately 135 degrees 0. when it flows from the pr1-. m'ary counter-current apparatus to the evaporatlng chamber 11..

- In the evaporating chamber 11, which infact constitutes'in effect a second countercurrcnt ap aratus, the com ressed air at'a pressure 0 c. .g. 50 atmosp eres is further cooled down by the boiling oxygen contained in said chamber an then ascends the pipe 13 and is expanded at thewalve 22. After leaving the expansion valve, the liquid air at a temperature of. about -190 degrees C. and 1 atmosphere pressure, descends the cylinder 14 and rises in the pipes 27, so that the pipe, 13 containing compressed-air is subjectel to the temperature reducing effect of the liquid air in the cylinder 14, so that the compressed air has its temperature further reduced before it reaches the expansion valve, at which point 'pheres before being released or expanded. It will thus be seen that the compressed air is subjected to the temperature reducing effect of at least three counter-current conditions before it is finally expanded from. the valve 22.

The rate at which the compressed. air is released and expanded at the expansion valve 22 can be controlled by means of the hand wheel 23. If this rate is such that liquefaction takes placeto a greater or less extent before the compressed air reaches the expansion valve, the liquefied ain will be forced up the pipe 13 by thespressure of the compressed air behind it and will escape the compressed unliquefied air. The expansion valve, however, will still accomplish its function of I, releasing the compressed air further reduction in temperature. This intense cooling action at the expansion valve makes this part of the apparatus the coldest, and causes what may be considered as a subcooling of the'air mixture. In the chamber 21 around the expansion valve, and in the coil 32, through which the gas mixture flows from the chamber 21, the liquefaction is .further effected as the temperature rises at the expansion valve to that of the new equilibrium between pressure, the

substantially about 50 atmosrate rst, together from that'- the liquefied-air and the- C. also serve to keep the coil cool and to assist in the separation of the liquid air from the gas mixture containing small drops in suspension, passing'through the coil.

From the above description of the operation taken in connection with the drawings and the description thereof, it will be'seen' that the process consists in primarily-cooliugcompressed air down to, a temperature of approximately -135 degrees C. by means of one or more of the constituents into which the liquid air then conveying the primarily cooled compressed air to a receptacle for the liquid oxygen to evaporate he latter and at the same time further reduce the temperature of the compressed air. Thecompressed air is then expanded. into a space having a lower pressure than that of the compressed air has been separated,

flows down through a h a return conduit which it flows into which the liquid air conduit and up throu from the upper ends 0 one or more long tubes, 1'. e., the tubes 31, or their equivalents, which are subjected to the heat of the rising gases from the oxygen tank to rectify the liquid air. In rectification of the liquid air the nitrogen gases emerge from the upper 31, and the oxygen flows from the lower end of said tubes into the receptacle 11 in liquid form. The nitrogen which flows from the upper ends of the tubes 31 into the chamber 19 is at a temperature of about. -190 degrees C. and a pressure of uparound 1 atmosphere. and flows about the coil 43 and then out through the pipe 41 tofthe primary counter-current apparatus 5 for the purpose heretofore set forth, a. 0., to reduce the temperature of the incoming compressed air.

According to the process described it will be seen that air is liquefied and is separated into its constituents, z. 0.. nitrogen and oxV: gen, by being rectified without allowing the vapors of liquid air or of liquid ox gen, or of'liquid air rich in oxygen, which furnish the heat for the rectificatiomto come into actual phvsical contact with the liquid air being heat and evaporate it, but bv the vapors generated from itself. for, as the air within the tubes is heated and partially evaporated, the nitro en being more volatile, tends to evapowith more or less oxvgen,

and as the vapors rise toward the top of the apparatus an equilibrium is established beends of the tubes rectified is rectified not by the vapors used to tween the rising vapors and the descending liquid oxygen b-fng condensed and nitrogen evaporated, with the result that the vapors become correspondingly richer and richer in nitrogen as they approach the top of the apparatus, and the liquid richer in oxygen as it approaches the bottom of the apparatus. The liquid air is'thus rectified by the establisluneut of an equilibrium within the tubes 31, between the liquid air itself and the vapors generated. from it, the liquid and vapors being separated from the heating vapoi-s surrounding the tubes.

As set forth, the heating of the tubes 31- can be effected by the vapors of'evaporated liquid air or liquid oxygen, rising from the chamber 11 and ascending around the tubes 31, these vapors being of a temperature approximately --183 degrees (1., so that the liquid air within the tubes 31 is nmintained' at a temperaturebetween that of the boiling point .ofthe liquid oXygen' and that of the liquid nitrogen at the particular pressure ready indicated.

at which the interior of the tubes is maintained, say about 1 atmosphere. This temperature of the liquid air is also somewhat controlled by the regulation of the air in the tubes, the temperature of this air gradually decreasing from the topdownward, and being maintained between the limits al- The process of the pres ent invention offers the advantages, however, that it can be carried out without elaborate apparatus for maintaining higher pressures, and the liquid air is rectified by vapors which are not brought in direct contact with the liquid air: while it is being" rectified. Y

' -What I claim and desire tosecure by Letters Patentof the United States isl. In an apparatus of the character described, a rectifying column for conducting "and rectifying liquid air in thin streams,

means for evaporating the liquid oxygen flowing from said column, and means for bringing the resulting vapors into heat 1nterchanging relation with the outside of.

said rectifying column whereby the vapors of the oxygen heat the column externally.

2. In an apparatus of the character described, means for supplying compressed air, means for liquefyin the compressed air, a rectifying column for the liquid air, means for evaporating the liquid oxygenflowing from the said column, means where-" by the vapors from the oxygen heat the column, and means for cooling the compressed air by said vapors.

3. In an apparatus of the character described, means for supplying compressed air, means for liquefying the compressed air, a rectifying column for the liquid air,

means for evaporating the liquid oxygen flowing from the said column by the heat from the compressed air, means whereby the vapors from the oxygen heatthe column, and means for'cooling the compressed air by said vapors.

4; In an. apparatus of the character described, means for supplying compressed to sai liquefied air, a receptacle for receiving liqaizr, meansfov li'quefyi the compressed axr',. a rectifylng column orthe liquid air,

saidcolumn, means for heating the liquid oxygen, and means whereby the resulting vapors heat. the said column.

In an apparatus of the character described, means for supplying compressed a r, means for liquefying the compressed air, a rectify ng column for the liquid air, means for catching liquid oxygen from the suidcolumn, means to heat the liquid oxymeans forcatching liquid oxygen from the gen by the ,compressed air, and means whereby the column 'is subjected to the resulting vapors.

6 In' an apparatus of the character described, means for supplying compressed a r, means for liquefying the compressed air, a rectifying column'for the liquid air, a receptacle for the liquid oxygen, a heating element for heating said receptacle heated by the' compressed air, and means whereby .the column is subjected to the resulting vapors.

Inan apparatus of the character described, means for supplying compressed air, meansfor liquefying the compressed air, a, rectifying column for the liquid air, a receptacle for the liquid oxygen, a heating coil insaid receptacle for, evaporating the oxygen therein, and means whereby the column is subjected to resulting vapors.

8. In an apparatus of the. character described, an expansion chamber, expansion means therein, a counter-current apparatus having a conduit for feeding compressed air to said means, a rectifying column for the liquefied air, a receptacle for receiving liquid oxygen from the said rectifying col umn, means to heat the contents of the re ceptacle from the compressed air conduit,

said receptacle'being arranged to have the resulting vapors heat the said rectifying column, and a conduit connecting said receptacle to the counter-current apparatus to subject the compressed air to the temperature reducing effects of said vapors.

9. In an apparatus ofthe character described. an expansion chamber, expansion means therein, a counter-current apparatus having a conduit foifeeding compressed air means, a rectifying column for the scribed, ,an expansion chamber, expansion means therein, means for supplying, compressed air to said means, a vertical shell connected to said chamber to'receive liquida rectifying column extending lengthwise of said shell, a conduit by means of which liquid air'is' delivered from said shell to the upperend of the column,

air therefrom,

a receptacle beneath thecolumn to receive expansion valve in the chamber, a pipe exapparatus of the character dechamber, a vertical tending through the shell and connected to the valve for supplying compressed air thereto, a distributing plate,- a plurality of rectif ing tubes leading from said plate, a tube or supplying liquid air from said shell onto the distributing plate, a receptacle for receiving liquid oxygen from said rectifying tubes, means for evaporating the liquid oxygenby means of theunexpanded compressed air, and for subjecting the rectifying 'tubes to the resulting vapors.

12. In an apparatus of the character'described, an expansion chamber, a vertical shell communicating with said chamber, an expansion valve in the chamber, a pipe extending through the shell and connected to the valve for supplying compressed air there to,a distributing plate, aplurality of rectifying tubes leading from said late, a tube for supplying liquid air from said shell onto the distributing plate, a receptacle for receiving liquid oxygen from said rectifying tubes, means for evaporating the liquid oxygen by means of the unexpanded compressed 8.11,

and for subjecting the rectifying tubes to the resulting vapors, and a counter-current ap aratus includin the compressed air conduit and conduits or the nitrogen and oxygen vapors.

13. In an apparatus of the character'described, an expansion chamber, a distributing plate, a plurality of rectifying tubes opening through said plate, a receptacle beneath said tubes, an expansion valve in said chamber, a conduit for compressed air ar{ ranged to heat said receptacle and supply compressed air to the expansion valve, and a counter-current apparatus for bringing the compressed air into heat interchanging relation with the separated constituents of the liquid air.

' -14. In an apparatus of the character'described, an expansion chamber, an expansion valve in said chamber, a conduit for supplying compressed air to said valve, a rectifying column for separating the liquid air into nitrogen and oxygen, and a plurality of counter-current means for successively subjecting the compressed air to the tempera- 'therein, and a pipe with said chamber, an

leased from the expansion valve;

15. An apparatus of the character de-.

before said compressed air is rescribed, comprising means for precooling the gas, an expansion valve, an expansion chamber surrounding said valve, means for conducting-therefrom the liquid separated coilsurrounding said chamber and arranged to conduct therefrom .the expanded gas and to separate a further amount'of liquid therefrom.

16. An apparatus of the character described, comprising an expansion 0 liquid collection tube below said chamber, and means for conducting the cold gas mixture in heat interchanging relation with the contents of said tube to said .expansion valve;

17. An apparatus of the character described, c'om rising an expansion valve, an expansion c amber around said valve, a

' liquidcollection tube below said chamber,

means for conducting the cold gas mixture in heat interchanging relation with the contents of said tubeto said expansion valve,

and a pipe coil surrounding-said expansion chamber and arranged to conduct therefrom the expanded as and to separate a further amount ofliquid therefrom.

18. An apparatus of the character described, comprising an expansion valve, an expansion chamber surrounding said valve, means for conveying therefrom the liquid separated therein, and a pipe co'il surrounding the expansion chamber, said coil leading at its upper end being provided with a discharge opening at its lower end.

19. An apparatus of the character described, com rising an expansion valve, an

expansion 0 iamber around the same, a liquid collection tube below said chamber closed at its lower end, means for conducting liquid from near the lower end of said tube to the exterior of said tube near its upper end, and a pipe coil surrounding said expansion chamber and arranged to'conduct therefrom the expanded gas and to separate a further amount of liquid from thesame, said coil also discharging exteriorly of the liquid collecting tube ear its upper end.

20. An apparatus of the character de-,

scribed, comprising conduits arranged to allow gradual flow therethrough in thin streams, means for feeding liquefied gaseous mixtures into the upper ends thereof and for discharging vapors therefrom, and means for heating said conduits externally without permitting medium to the interior of the conduit.-

21. An apparatus of the character described, comprising conduits arranged .to

expansion valve, an amber around said valve,- a-

from said chamber and access of the heating a allow gradual flow therethrough in thin streams, means for feeding lique ed gaseous mixtures into the upper ends thereof and for discharging va iors therefrom, and

means for heating said conduits externally by the vapors of evaporated li aid.

22. An apparatus of the ciaracter described, comprising coils of pipe arran ed with a gradual inclination to permit ow therethrough in thin streams, means for feeding liquefied gaseous mixtures into the upper ends thereof and for discharging vapors therefrom, and means for heating said pipes externally without permitting access of the heating vapors to the interior of the conduit:

23. An apparatus of the character described, com arising a plurality of coils of pipe of gra nal inclination for permitting flow of liquefied gaseous mixtures therethrough in thin streams, means for feeding liquehed gaseous mixtures into the upper ends thereof and for permitting escape of vapors therefrom, a liquid receptacle into which the lower ends of said coils discharge, and means for vaporizing the ll( uid in said receptacle Ior heating said coils to effect rectification of the mixture therein.

24. An apparatus of the character described, comprising co of pipe arran ed with a gradual inclination to permit ow of liquid therethrough in thin streams, means for feeding liquefied aseous mixturcs into the top thereof and or discharging vapors therefrom, a lir uid receptacle at the lower ends of said coils forming a. seal therefor, and means for vaporizing the liquid in said lit uid receptacle for heating said coils externally.

25. An apparatus of the character described. conqirising a plurality of coils of pipe of gratual inclination for permitting flow-oi liquefied gaseous mixtures therethroa h in thin streams, means for feeding liqucla-d gaseous mixtures into the upper ends thereof and for permitting escape of vapors therefrom, a liquid receptacle into which the lower ends of said coils discharge, and means comprising a pipe coil for heating and vaporizing the liquid in said rece taclo for lting said first-mentioned cm s to client rectification of the mixture therein.

.26. An apparatus of the character described. comprising means for precooling a compressed gaseous mixture, means for expanding am liquefying said gases, a liquid receptacle for the liquefied gas, coils of pipe of gradual inclination for permitting flow of the liquid therethrough in thin streams, means for feeding the liquid from said liquid receptacle into the upper ends of said code, means for heating said coils externally and means for discharging from the said coils the vapors formed therein.

27. An apparatus of the character described, comprising an expansion valve, an

counter-currently compressed expansion chamber and liquid receptacle for the expanded and liquefied gas, and'n cans for rectifying said liquefied gas comprising coils of gradual inclination arranged to receive liquid from said liquid receptacle and to conduct the same in thin streams and means for heating said coils externally bv the va )ors of evaporated liquid.

2-8. x n apparatus of the character described, comprising an expansion valve, an expansion chamber and li uid receptacle forthe expanded and liquehcd' gas, a pipe coil surrounding said expansion chamber and arranged to conduct therefrom the expanded gas and to separate a further amount of liquid therefrom, and means for rectifying said lhuclicd gas comprising coils of gradual inclination arranged to receive liquid from said liquid receptacle and from said first mentioned coil and to conduct the same in thin streams, and means for heating said rectifying coils externally by the vapors of evaporated liquid.

29. An apparatus of the character described. comprising an expansion valve, an ex )ansion chamber around said valve. a liqui receptacle below said chamber, rectifyin 3' coils of gradual inclination surrounding said liquid receptacle for permitting llow of liquid therethrough in thin streams, means for feeding liquid from said liquid receptacle into said tubes, a second liquid receptacle below said coils arran cd to receive liq'uid therefrom, and means or heating and evaporating the liuiid in said last-mentioned receptacle ant conducting the resulting vapors into heat interchanging relation with said rectifying coils to eli'cct rcctil'ication of the liquid therein.

30. An apparatus of the character described, comprising an expansion valve, an expansion cuunbcr around said valve. a pipe coil leading from said expansion chamber and surroumlin the same and arranged to discharge the vapors and liquid so )arated therein at its lower end, a liquid tu e leading downward from said cxpansion chamber for the liquelicd gases and closed at its lower end, rectifying coils of gradual inclination for permitting flow thercthrough of liquid in thin streams, said coils being provided with means for permitting inflow of liquid and outflow of vapors therefrom, means for conveyin the liquefied uses from near the bottom of said liquid tu e to the tops of said rectifying coils, means for heating said rectifyin coils externally, and a conduit for the (Kilt conr pressed gases extending upward through said li uid tube to the expansion valve. H

8 1. n apparatus of the character described, comprising means for cooling uses, an exansion valve, :1 liquid tube f ed gases below the expansion valve, coils or the lique-- of ipe of gradual inclination surrounding sai liquid tube, ipes leading from near the bottom of said 'quid tube to the tops of said coils for conveying liquid thereto, a liquid receptacle below said coils for receiving liquid therefrom, and means for vaporizing iquid in said receptacles for heating said coils externally.

32. An apparatus of the character described, comprising means for rectifying liquid air and separatin the same into liquid rich in oxygen an vapors rich in nitrogen, a liquid receptacle for said liquid rich in oxygen, a coil in said receptacle for heating the same, a casin in said receptacle provided with restricts inlet and outlet openings at its top and bottom and inclosed by' said heating coils, an outlet pipe leading from the interior of said casing, and a smaller casing surrounding the end of said outlet ipe within the larger casing.

33. n apparatus of the character described, comprising an expansion valve, an expansion chamber and liquid receptacle for the expanded and liquefied gas means for rectifying said liquefied gas and separating the same into liquid rich in oxy on and vapors rich in nitrogen, a liqui receptacle or the liquid rich in oxygen at counter-current piping for precooling e gases before expansion, and a conduit or said precooled asce arranged to convey said gases from t is counter-current piping to the expansion valve throu b said receptacle for liquid'rich in ex on or heating and vaporizin the liquii in the same and through sai first mentioned liquid receptacle.

M. An apparatus of the character described, comprising means for cooling counter-currently compressed gases, on expansion valve for expanding and partially iquefying the same,'a liquid tube for the liquefied gases below the expansion valve, coils of pipe of gradual inclination surrounding said liquidtube, pipes leading from near the bottom of said liquid tube to the tops of said-coils for conveying liquid thereto, a liquid receptacle below said coils for receiving liquid therefrom, and means for vaporizing liquid in said receptacle for heating said coils externally comprising a conduit for the cold compressed gas lending to the expansion valve in heat interchanging1 relation with said liquid receptacle and sai liquid tube.

85. An apparatus of the character described, comprising a counter-current piping for precooling com ressed gases, an expansion valve for lique ying the same, an expansion chamber surrounding the same, a liquid tube below said chamber, rectifying coils of gradual inclination surrounding said tube, means for conveying liquid from said tube to said coils near their upper ends, a liquid receptacle below said coils arranged to receive liquid discharged therefrom, and means for evaporating the liquid in said receptacle to heat said rectifying coils comprising a pipe leading from said countercurrent iping through said liquid receptacle int e form of a coil and through said liquid tube to the expansion valve. v

36. In an apparatus of the character de scribed, means for supplying compressed air, means for 1i uefymg the com ressed air, a rectifying co umn for the lique ed air, means for evaporating the liquid oxygen flowing-from the said column, and means for bringing the resulting vapors into heat-intcrehanging ternally without permitting access of said vs era to the interior of the column.

n testimony whereof I have hereunto signed my name in the presence of two eel scribing witnesses.

GOTTHOLD nrnnnsnann'r.

Witnesses Wowmum Ham, Hnnar Hasrna.

Copies of this patent may be obtained for In cents sseh. by addressing the Commissioner or latenta,

, Washington, D. 0."

relation with said column can

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