US711525A

US711525A - Apparatus for liquefying air.

Info

Publication number: US711525A
Application number: US9565302A
Authority: US
Inventors: James F Place
Original assignee: SAMUEL M GARDENHIRE
Current assignee: SAMUEL M GARDENHIRE
Priority date: 1902-02-26
Filing date: 1902-02-26
Publication date: 1902-10-21
Anticipated expiration: 1919-10-21

Description

Patented Oct. 2|, I902.- J F PLACE APPARATUS FOR LIHUEFYING AIR.

(Application filed Feb. 26, 1902.) (No Modl.)

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. Patented Oct. 2|, I902. J. F. PLACE. APPARATUS FOR LIGUEFYING AIR;

(Application filed my. 26, 1902.

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Patented .Oct. 2|, |902. 4. r. PLACE. APPARATUS FOR LIHUEFYINQAIR.

(Application filed. Feb. 26, 1902.)

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UNITED STATES PATENT OFFICE.

JAMES F. PLACE, OF GLENRIDGE, NElV JERSEY, ASSIGNOR OF ONE-HALF TO SAMUEL M. GARDENHIRE, OF BROOKLYN, NEW YORK.

APPARATUS FOR LIQUEFYING AIR.

SPECIFICATION forming part of Letters Patent N 0. 711,525, dated October 21, 1902. Application filed February 26, 1902. Serial No. 95,653. iNo modeL),

To all whom, it may concern:

Be it known that I, JAMES F. PLACE, a citizen of the United States, and a resident of Glenridge, in the county of Essex and State of New Jersey, have invented certain new and useful Improvements in Apparatus for Liquefying Air, of which the following is a specification.

My invention relates to improvements in machines, apparatus, appliances, or devices for liquefying atmospheric air.

The object is to produce liquid air in larger quantities and at less expense than has heretofore been done.

Up to the present time the usual Way of producing liquid air is by what is called the throttled free nozzle and self-intensive method. Other ways and other mechanism have been suggested; but none other has been adopted for producing liquid air as a commercial article, so far as I know.

My invention comprises an air reciprocating expansion engine or air-expanding motor insulated as thoroughly as possible from the heat of the outside atmosphere, (arranged to operate without lubrication inside,) in combination with an air-compressor and various appliances and apparatus for cooling,

drying, and purifying the air before liquefaction and for transferring the heat of the incoming compressed air before expansion in the engine to the outgoing cold exhaust and expanded air from such engine. The fall of temperature obtained by allowing com pressed air to expand without doing workas, for instance, in escaping through a throt tled free nozzleis very small, less than half a degree (Fahrenheit) for each atmosphere of pressure. Thus a fall or drop from ninetypounds gage-pressure to atmospheric pressure (at a normal temperature of 60 Fahrenheit, say) cools the expanded air as it leaves the nozzle only about two and a quarter degrees, (2%,) so small a fall in temperature as 5 to hardly be noticeable. If this compressed air (at ninety-pounds gage and at 60 Fahrenheit) were expanded in a thoroughly-insulated expansion-engine against resistance, (or was made to do work as it expanded,) its temperature would drop to 165 Fahrenheit below zero, a fall in temperature one hundred times as great as obtained by the freenozzle expansion, and if the next charge of com pressed air delivered to the engine were cooled by the exhaust-air, so that the initial temperature were 165 below zero instead of above, then the expanded air therefrom after doing work would have a terminal temperature of 292 Fahrenheit below zero, and if the next charge to the engine were cooled 60 by this cold exhaust or expanded air to that temperature (-292) and then expanded against resistance the exhaust or expanded air therefrom would drop theoretically to about 364 Fahrenheit below zero or to a point 52 colder than the temperature of liquefaction (-3l2 Fahrenheit) at atmospheric pressure.

The idea per se is not new of liquefying air by expanding it against resistance. Many inventors and writers have recognized the advantages of this system since Siemens filed his application for an English patent in 1857 for improvements in refrigerating and producing ice by the expansion of air. Only in late years, however, has the subject of liquefying air in that way attracted attention, and by those most familiar with the liquefaction of gases the subject has been abruptly dismissed, apparently without either investigation or experiment, on the assumption that it was impracticable,for the reason, as alleged, first, that an engine cannot be lubricated at 220 below zero and thatit will notrun without lubrication, and, second, that it is impossible orimpracticable to insulate an enginecylinder against the heat of the outside atmosphere, and, as further alleged, third, thatthe moisture in the air will form ice around the valves and in the cylinder, overlooking the fact, apparently, that the mois- 9o ture can be removed. All three of these assumptions are without foundation.

First. Engines of the ordinary cylinderand-piston type even can be run and are running without lubrication, and they run bet- 5 ter at low temperatures than at highbetter cold than hot-and the friction in the'cylinder when piston-rings of light tension are used and when run at ordinary speed is so light as to be scarcely noticed. High speed is not required in an expansion-engine when used for refrigerating purposes, and I have found from personal experiments made that the colder the engine-cylinder becomes the less is the friction of the piston-rings.

Second. An engine-cylinder can be as easily and thoroughly insulated from the heat of the'surrounding atmosphere as an ordinary steam-pipe can be insulated from the air itself, the problem of difference in temperatures is no greater, and under proper mechanical construction this difficulty practically vanishes.

Third. The moisture is taken from theair in my apparatus before it is used in the engine, and where there is nothing to freeze there is not likely to be any trouble from ice.

In my invention I thoroughly insulate the engine from the heat of the surrounding atmosphere, which has not heretofore been done or even suggested. I do this by, first, an exhaust-chamber, which envelops or completely surrounds the engine next to the cylinder-walls, so that the cold expanded and exhaust air as it leaves the cylinder passes all around the cylinder-walls outside the cylinder, thus forming a thoroughly-cold insulating-envelop for the same, and, second, I further insulate said exhaust-chamber and its inclosed expansion cylinder by a vacuumjacket, which surrounds or incloses said exhaust-chamber, as well as said inclosed expansion-cylinder, thus forming a still greater and more perfect insulation from the outside atmosphere, and, third, I further insulate all the parts, including the doublyinclosed and doubly-insulated expansion-cylinder, the insulated and inclosed exhaustchamber, and the enveloping vacuum jacket or chamber by outside coverings or packings of hair, felt, or other material of low heat conductivity, and also I further insulate by inclosing said insulated engine-cylinder within the helical coils of a thermal interchanger and surround or inclose the whole by deadair spaces and a case of wood or some other suitable material. This thorough insulation of the expansion-engine cylinder by the cold exhaust chamber inclosed by the vacuumjacket and other insulations is one of the special features of myinvention, and thorough insulation is necessary to the successful operation of the apparatus or to obtain the best results and greatest possible efficiency of the mechanism or apparatus.

I am aware that an enveloping exhaustchamber surrounding an air-expansion eugine is not new; but such insulation is insufficient, even though surrounded by outside packings of non-conducting materials, and

to meet the requirements I have combined with such exhaust-chamber a vacuum-jacket which is an ideal insulator against heat. While a vacuum-jacket has been used as an insulator for a counter-current or refrigerating coil or for liquid-air containers or receptacles, so far as I know it is an entirely new and original device for insulating an expansion-engine from the heat of the atmosphere.

Its combination with a cold and expanded air exhaust chamber surrounding the engine, whether the vacuum-jacket incloses the engine first or next thereto and is then surrounded by the exhaust-chamber or Whether, as herein shown as the preferred construction, the cold-exhaust chamber is next to the engine and is inclosed by the vacuum-jacket, forms almost a perfect insulator and meets the requirements better than any other combination. High initial pressures can be used, however, in my apparatus,and probably with much economy, whether the machine or apparatus is used for making liquid air or for obtaining power from the normal heat of the atmosphere, for the reason, first, that the fall of temperature of the air in the engine due to transforming its heat into mechanical work is so much greater than in thefree-nozzle system and so instantaneous and so absolutely positive with every operation, and, second, because of the fact that the latent heat of condensation grows less and less with the increase of every atmosphere of pressure until the critical pressure (thirty-nine atmospheres or five hundred and eighty-five pounds) and the critical temperature (220 Fahrenheit) is reached, when it vanishes entirely.

Latent heat would naturally cause the mean temperature in the expansion-engine cylinder to range a little higher than otherwise as liquefaction progressed and would prevent a fall below the critical temperature; but if a sufliciently high initial pressure is used then the cut-off and expansion may be such so that the terminal pressure will not fall below thirty-nine atmospheres and the terminal temperature due to work done will fall to a point not above -220, in which case there will be no latent heat given out in the expanding air during the process of condensation to its liquid form. Even if these conditions of critical pressure and critical temperature are but approximately reached at the end of expansion in the engine the latent heat of condensation is correspondingly less as those conditions are approached and is likely to be so small as not to appreciably retard the great and instantaneous fall of temperature due tothe transformation of heat into mechanical work, which fall of temperature must, and with proper insulation of the engine-cylinder will, at each and every stroke be exactly equivalent to the full amount of work done, and which fall in temperature, as I have shown, will be about one hundred times as great (or as cold) as that obtained by expansion of air through a nozzle.

In addition to thorough insulation of the expansion-engine my invention comprises a construction thereof of such a character as to-avoid lubrication of such parts as Work at very low temperatures and also such construction as reduces the friction of such parts to the minimum.

My invention also comprises a counter-current thermal interchanger or self-intensive apparatus insulated from the heat of the outside atmosphere and of maximum efficiency, as the conduit carrying the outgoing or coldexpanded air practically begins at the exhaust-port of the expansion or liquefying engine and substantially surrounds the incoming compressed air from the cutoffvalve chamber to the cooler attached to the compressor as a continuous counter-current to said incoming compressed air.

It also comprises a new and novel and effective purifying and moisture-extracting or air-drying apparatus, whereby the incoming compressed air is thoroughly dried while it is being cooled by an outgoing counter-current of cold-expanded exhaust-air from the liquefying-engine and whereby the moisture as it is absorbed from the incoming compressed air by the chemical action of calcium chlorid or some other hygroscopic substance dissolves the said hygroscopic substance and forms a purifying brine or solution through which the air is passed before it comes in contact with the undissolved substance.

My invention also comprises in combination the connections, valve-gear, outside stuffingboxes, and various other devices and appliances for securing perfect insulation of the engine and performing the work required thereof, as will be more fully hereinafter described and as illustrated in the accompanying drawings, of which- Figure 1 is a View, partly in vertical section and partly a side elevation, of my complete thermodynamic air -.liquefying apparatus, showing the air-compressor and the watercooler for removing the heat of compression, the purifying-brine tank or trap connected with the moisture-extracting cylinder or drying-drum inclosed by the helical countercurrent cooling-passages for the outgoing expanded air and its outside protecting and insulating case, and also showing a modification in construction of expansion-engine, &c., and how same may be used in connection with my system of obtaining power from theheat of the atmosphere, &c., for whichsystem or process, as well as the apparatus required therefor, applications Serial Nos. 88,437 and 112,043 for United States patents are now pending. Fig. 2 is an enlarged View, in vertical section, of my improved air-liquefying engine with cut-off and exhaust-valve gear, insulating exhaust-chamber, vacuum-jacket, outside insulating-packings of hair, felt, or other insulating material. Also is here shown the preferred construction of the insulated thermal interchargerreturn or counter-current coils-for cooling the incoming compressed air by such portions of the cold exhaust-air as do not become liquefied. Fig. 3 is a vertical section of the liquefying-engine similar to that shown in Fig. 2, but showing in this figure the dead-air-insulating spaces in the outside protecting-case which incloses the engine. Fig. 4 is a horizontal cross-section of the air-liquefying engine on the line X X of Fig. 2, showing in detail the small area of metal supports, 850., through the vacuum from outside to the expansion-engine cylinder. Fig. 5 is a horizontal cross-section of the air-expansion cylinder on the line Y Y of Fig. 2 through the valves, valve-chambers, and piston. Fig. 6 is a more detail of the engine crank-yoke, as shown in Fig. 2. Any other style of crank connection may be used.

Similar reference-marks refer to similar parts throughout the several drawings.

The numeral 1 in Figs. 1, 2, and 3 is my expansion-engine or air 4 liquefying engine, which is shown in Figs. 2 and 3 as an upright engine, which is the preferred construction, 2 being the air-expansion cylinder wherein compressed air is expanded against resistance or is made to do work against the piston 98.

3, Fig. 2, is the insulating exhaust-chamsure annular conduit of the thermal inter-1 changer, to be hereinafter described, and the other a gravity liquid-air outlet or passage 7, Fig. 2, which allows the liquid air which accumulates in the exhaust-chamber 3' to pass out by gravity into the liquid-air receptacle 105 outside.

The insulating-

chambers

3 and 5, Fig. 2, are double insulating-chambers, and the two together, as will be noticed, substantially inclose the said reciprocating expansion engine, this furnishing a double insulation against the normal heat of the outside atmos-' phere for said engine, one of said chambers being an insulating cold-exhaust chamber and the other an insulating vacuum chamber or jacket.

The coils 26 and 27 (see Fig. 2) comprise what I call my counter-current thermal interchanger, which consists of the compressed-air or high-pressure coil or conduit 26 and the expanded-air or cold-air low-pressure coil or annular conduit 27, which incloses within it the high-pressure coil. Said counter-current thermal interchanger is located outside of both the double insulatingchambers, as will be noticed, and is arranged as an insulating helical coil surrounding or inclosing said double insulating-chambers within its folds or coils. The coil or conduit 26 is fed from the air-compressor 53 (see Fig. 1) primarily by the discharge-pipes 56 and 59 through the drying-drum 58 and the cock 104,

ICC

and after passing through the interchanger it delivers the cooled and dried compressed air to the expansion-engine through its cutoff valve or

valves

32 and 32. The low-pressure annular conduit 27 is fed from the exhaust-chamber 3 through the passage 6, and the outgoing cold exhaust or expanded air therefrom passes, as will be seen, in a counter-current or contrary direction to the incoming compressed air in conduit 20, and after leaving the interchanger-coil it passes through pipe (see Fig. 1) into the helical passage 61, around the drying-drum, and is finally delivered to the suction of the aircompressor through pipe 62.

The incoming compressed air as it passes through the drying-drum 58 and also through the high-pressure helical coil 26 of the interchanger gives up its heat to the outgoing coldexpanded exhaust-air in the insulated helical passage 61 and in the counter-current lowpressure annular helical conduit 27, and leaving the interchanger at 28 (see Fig. 2) now free from moisture and at same low temperature practically of the exhaust-air it enters check-valve 30 and valve-stem passage 29 into the cut-oif-valve chamber 33. I use an ordinary fixed cut-off-valve gear, as shown at 31, Fig. 2, having balanced puppet cut-off

Valves

32 and 32. Any other form of cu t-offvalve gear will answer; but by using that style shown in Figs. 2 and 3, however, I can make use of the Valve-stem passage 29 as a compressed-air-inlet port (around the stem 47) or protected passage for the air to pass in through the vacuum-jacket 5 into the cut-offvalve chamber 33, and by using the exhaustvalve gear 34 (shown in Fig. 2) I can make use of the exhaust-valve-stem passage 35 (around the stem 47) as an outlet for the expanded cold exhaust-air (or that which has not become liquefied) to pass from the exhaust-chamber 3 out through vacuum-jacket 5 and deliver same to the low-pressure annular conduit 27 of the counter-current thermal interchanger at 36. (See Figs. 2 and 3.) The protecting-walls 29' and 6 of these passages 29 and 35 I make use of to support the expansion-engine from the frame 37,as shown, by the

braces

38 and 38, Figs. 2 and 3. Thus it will be seen that the only connection between the engines cylinder 2 and the outer protecting-case may be through the two

supports

38 and 38, Fig. 2, and the sleeeve inclosing the gravity-passage 7 at the bottom, and these are insulated by the wooden tubes or supports 41 and 41', Fig. 3, at the top and 41 at the bottom within the insulating deadairspace 45, Fig. 3, fixed between the inner and outer walls of the outer protecting-case 37, Fig. 3.

The piston-rod 42, Figs. 2 and 3, I inclose in a long sleeve 43, which is made so that the passage 44 is just a trifle larger diameter than the rod, and the rod slides therein without coming in contact with the sleeve. This sleeve extends from the expansion-cylinder through both the double insulating-chambers, so as to retard the passage of heat in, through, or around the piston-rod,and is provided with a stuflingJoox preferably at the outer end. This protecting-sleeve 43 and the protectingwalls 29' and 6 or sleeves around the

passages

29 and 35, Fig. 2, form the total metal connection between the expansion-cylinder 2 and the outside or inclosing Wall of the vacuumjacket 5. Thus the area of heat conductivity is reduced to the minimum. I inclose the valve-stems 47 and 47, Fig. 3, also by

long sleeves

48 and 48, so that the stems slide therein without contact in order to retard the passage of heat down the stems.

Mounted on the frame 37, Fig. 2, I have an engine-crank 49, fly-Wheel 50, and

eccentrics

51 and 51. Any other style of engine and connections will answer equally as well. The engine is shown doingwork in Fig. l by assisting in driving the air-compressor 53. At 54, Fig. 1, is shown a pulley connected with an outside source of power, which is arranged to drive the air-compressor with or without the assistance of the air liquefying or expansion engine. Itis absolutely necessary, however, that the expansion-engine shall do work in order to transform the heat of the compressed air into mechanical work, and thereby cause the necessary fall in temperature to liquefy the air as it expands.

At 55, Fig. 1, I show an ordinary watercooler for removing the heat of compression from the compressed air. The compressed air after passing through the cooler 55 then is conducted into the purifying-brine tank or trap 57 through the inlet-pipe 56, which enters the trap at or near the bottom thereof, so that the air is passed through the brine or other purifying solution contained in the trap.

At 58, Fig. l, I have a compressed-air storage-reservoir or air-drying drum or cylinder which is filled with calcium chlorid or some other hygroscopic or moisture-absorbing substance in or on a series of pans or shelves, as at 58, which have screen-bottoms, so the air can readily pass up through the same successively and through or in contact with the hygroscopic substance. The purifying-tank 57 is attached to the lower end of the dryingdrum 58 and is connected therewith by the pipe or conduit 59, and the air-drying drum 58 has a com pressed-air-outlet pipe at or near the top of same, so that the purified and thoroughly-dried air passes out through the cock 104 into the high-pressure conduit 26 of the thermal interchanger. The purifyingtank 57 I fill with an initial charge of calcium-chlorid brine, makinga strong solution, so that besides purifying and removing dust, oil, 850., more or less moisture is also extracted from the air by the brine, and as this air then passes up into the drying-drum and through or over or in contact with the chlorids or other hygroscopic materials the moisture is effectually absorbed or taken up from the air and forms a brine orsolution with the dissolved hygroscopic substance, which drips down through the air-conduit 59 into the trap 57, thus keeping continually replenished the purifyingsolution therein.

The expanded cold air which is discharged from the expansion-cylinder into the insulating exhaust-chamber 3 during the working of the engine and which has not liquefied passes all aroundthe expansion-cylinder in the chamber 3, thus insulating and keeping said cylinder very cold. It finally passes up through the protected passages 6 and 35, Figs. 2 and 3, into the low-pressure annular conduit 27 of the counter current thermal interchauger. This annular conduit 27 incloses the pipe 26, and the cold expanded exhaustair which has not liquefied, as well as any vaporized liquid air in the chamber 3, passes out through the helical annular conduit 27, Figs. 2 and 3, in a direction contrary to that of the incoming compressed air in the high-pressu re coil 26,-and thus the air in the pipe 26 rapidly gives up its heat to the outgoing cold expanded air in conduit 27, which incloses the compressed-air pipe 26. The expanded air after leaving the interchanger passes through the pipe 60, Fig. 1, into the helical passage 61 around the drying drum 5S, and thereby serves to cool and insulate the compressed air in the drying-drum. The drum is further insulated by the packings of hair felt 100 or other material.

In the construction of my liquefying expansion-engine I aim to reducethe friction to the minimum, especially within the expansion or liquefying cylinder and in the movement of the valves, and also I aim to secure the greatest possible insulation against the heat of the outside atmosphere. The piston 98, Fig. 2, may be of'the ordinary type; but I make the pressure-holding rings 99 practically frictionless. I prefer cast-iron rings for piston-packing in a refrigerating-engine cylinder, although leather packing may be made suitable; but in either case neither lubricant nor lubrication should be used. I

Thorough insulation of the liquefying-engine from the normal heat of the atmosphere is essential. In the construction shown in Figs. 2 and 3 the liquefying-cylinder 2, it will be noticed, is almost completely inclosed by the cold-exhaust chamber 3, the only exception thereto being the piston-rod sleeve 43 and the valve-stem sleeve 29 and the support 6 through the chamber, (see Fig. 4,) and the exhaust chamber is almost completely inclosed by the vacuum-jacket 5, the only exception being'the three

sleeves

43, 6, and 29, Fig. 2, and the sleeve inclosing the gravity liquid-air outlet 7 ,which also serves as a stand or support for the vacuum-jacket 5 and exhaust-chamber 3. The whole is also inclosed or surrounded by the helical coils of the thermal interchanger, Figs. 2 and 3, and still further insulated by the packings of hair felt 101 or other materials of low heat conductivity,

which packings and interchanger are also completely inclosed by the outside case or frame, of wood or other suitable material, and formed, as shown in Fig. 3, with deadair spaces 45 all around it.

In Figs. 1 and 3 the numerals and reference-marks 8, 8 8 12, 12, 7', 9, 13, 13, 13, 21, 21, 22, 22, 23, 23, 24, 24, 24, 24, 25, 25, 63, 64, 66, 66, 67, 68, 69, 69', 70, 70, 71, 72, 73. 75, 76, 76, 77, 81, 81, 82, 84, 84, 85, 85, 86, 86, 88, 90, 90, 91, 91, 92, 92, 93, 93, 94, 94, 95, 95, 96, 97, 97, 110, 111, and 112 refer to parts of the apparatus when used for obtaining power from the normalheat of the atmosphere, as described in my application for Patents Serial Nos. 88,437 and 112,043.

The operation of my invention is as follows: The air-compressor 53, Fig. 1, is attached to the source of power 54 and is started. Air is drawn in through the suction 53 and after being compressed is discharged into the pipe 56 and through the water-cooler 55, where the heat of compression is removed. It is then delivered to the purifying tank or trap 57 and is passed through the brine or calcium-chlorid solution therein, the impurities being thereby removed and more or less moisture absorbed from the air. From this purifying-tank the air passes through the connectingpipe 59 into the drying-drum 58, where the moisture is effectually absorbed therefrom by the successive charges of cal- .cium chlorid or other hygroscopic substances therein. Whenever a suflicient pressure is indicated by the gage 96, the cock 104 is opened and the now purified and thoroughlydry compressed air passes into the highpressure coil 26 of the thermal interchanger, (see Figs. 1 and 2,) and after passing through said interchanger is delivered through the check-valve 30 into the cut-off-valve chamber 33 of the expansion or liquefying engine. It enters the cylinder 2 and is cut off at very short stroke, (varying according to pressure,) so that as it expands against the resistance of the piston 98'its pressure falls and its temperature drops to a point corresponding to the amount of work done. The cold expanded air is then discharged from the cylinder 2 into the exhaust-chamber 3, where it circulates around the cylinder and passes out through the-passage 6 and 35 into the counter-current coil or annular conduit 27 of the thermal interchauger. As this cold expanded air passes down and out through the helical annular conduit 27it cools the incoming compressed air in the high-pressure coil 26 or takes up heat from said incoming compressed air, so that the following portions or successive charges of compressed air deliveredto the cut-ofi-valve chamber 33 will be at a very muchlower temperature than u ed air as delivered to the exhaust-chamber 3. This fall in temperature is large and very rapid, owing, to the disappearance of the heat transformed into mechanical work, as heretofore explained. After a few strokes of the piston portions of the air will become liquefied and will accumulate in the bottom of the exhaust-chamber 3 and may be drawn off through the passage 7 into the vacuum-jacketed liquid-air receptacle 105. (See Fig. 2.) The unliquefied portions pass up around the engine-cylinder 2 and out through the interchanger, as heretofore explained, and are finally delivered through the pipe 62 to the air-compressor again, so that the compressor will only draw new free air sufficient to make up for the quantity liquefied during the operation.

The advantages of producing liquid air by my apparatus in preference to the throttled free-nozzle method are very great, and the cost of such production is but a small fraction of the cost by the free-nozzle method, for the power obtained from the expansionengine while working, whatever percentage it may be of the power required to drive the air-compressor, is a gratuity or clear gain, and the fall in temperature per unit of energy expended (which is the measure of economy) is, as I have shown, about one hundred times as great as in the free-nozzle system.

Having thus described my invention, what I claim as new and original, and desire to secure by Letters Patent, is-

1. In a machine or apparatus for liquefying air the combination of a reciprocating expansion-engine, provided with a cut-off valve or valves and means for operating the same; double insulating-chambers substantially inclosing said engine, one of said chambers being an exhaust-chamber connected with the cylinder of said engine, and the other being a vacuum-chamber; and a countercurrent thermal interchanger located outside of said insulating-chambers, said interchanger being arranged as an insulating-coil, surrounding or inclosing said double insulating-chambers within its folds or coils, substantially as shown and described.

2. In a machine or apparatus for liquefying air the combination ofa reciprocating expansion-engine, provided with a cut-off valve or valves and means for operating the same; double insulating-chambers substantially inclosing said engine, one of said chambers being an exhaust-chamber connected with the cylinder of said engine, and the other being a vacuum-chamber; and a counter-current thermal interchanger located outside of said insulating-chambersg said engine having a sleeve around the piston-rod of same, extending from the expansion-cylinder through said double insulating-chambers, and provided with a stuffing-box at the outer end thereof, substantially as shown and described.

3. In a machine or apparatus for liquefying air the combination of a reciprocating expansion-engine, provided with a cut-off valve or valves and means for operating the same; double insulating-chambers substantiallyinclosing said engine, one of said chambers being an exhaust-chamber connected with the cylinder of said engine, and the other being a vacuum-chamber; and a countercurrent thermal interchanger located outside of said insulating-chambers, said interchanger being arranged as an insulating-coil, surrounding or inclosing said double insulating-chambers within its folds or coils, said engine havinga sleeve around the piston-rod of same, extending from the expansion-cylinder through said double insulatingchambers, and provided with a stuffing-box at the outer end thereof, substantially as shown and described.

4. In a machine or apparatus for liquefying air the combination of a reciprocating expansion-engine, provided with a cut-off valve or valves and means for operating the same; double insulating-chambers substantially inclosing said engine, one of said chambers being an exhaust-chamber connected with the cylinder of said engine, and the other being a vacuum-chamber; and a counter-current thermal interchanger located outside of said insulating-chambers, said engine having a sleeve around the piston-rod of same, extending from the expansion-cylinder through said double insulating-chambers, and provided with a stuffing-box at the outer end thereof; and a gravity liquid-air passage leading from the inner insulating-chamber and passing through the outer one of said double chambers, and delivering to a liquid-holding receptacle outside thereof, substantially as shown and described.

5. In a machine or apparatus for liquefying air the combination of a reciprocating expansion-engine, provided with a cut-off valve or valves and means for operating the same; double insulating-chambers substantially inclosing said engine, one of said chambers be ing an exhaust-chamber connected with the cylinder of said engine, and the other being a vacuum-chamber; and a counter-current thermal interchanger located outside of said insulating-chambers; said engine having a sleeve around the piston-rod of same, extending from the ex pansion-cylinder through said double insulating-chambers, and provided with a stuffing-box at the outer end thereof, and two outlets from said inner insulatingchamber in form of protected passages through the outer one of said double insulating-chambers, one a cold expanded air or vapor outlet delivering to the low-pressure coil of said thermal interchanger and the other a gravity liquid-air passage delivering to an outside liquid-holding receptacle, substantially as shown and described.

6. In a machine or apparatus for liquefying air, the combination of a compressed-air engine having an expansion-cylinder, provided with a piston having pressure-holding rings IIO of very light tension so as to run in said cylinder without lubrication and with practically no friction, and also provided with a cut-off valve or valves and means for operating'same, and with suitable connections for expanding air against resistance; double insulating-chambers substantially inclosing said engine, one of said chambers being an exhaust-chamber connected with the cylinder of said engine, and the other being a vacuumchamber; and a'counter-current thermalinterchanger consisting of a high-pressn re coil or conduit connected with and delivering to said expansion-engine through said cut-off valve or valves, and a low-pressure coil or annular conduit inclosing said high-pressure coil and which is connected with and fed from said exhaust-chamber; said interchanger being located outside of said insulating-chain'- bers, and arranged as an insulating-coil surrounding or inclosing saiddouble insulatingchambers within its folds or coils, and a gravity liquid-passage or protected conduit leading from said exhaust-chamber and passing through said vacuum-jacket, and delivering to a liquid-holding receptacle outside thereof, substantially as shown and described.

7. In a machine or apparatus for liquefying air, the combination of a compressed-air engine having an expansion-cylinder, provided with a piston having pressure-holding rings of very light tension so as to run in said cylinder Without lubrication and with practically no friction, and also provided with a cut-off valve or valves and means for operating same, and with suitable connections for expanding air against resistance; double insulatingchambers substantially inclosing said engine, one of said chambers being an exhaust-chamber connected with the cylinder of said engine, and the other beinga vacuumchamber; and a counter-current thermal interchanger consisting of a high-pressure coil or conduit connected with and delivering to said expansion-engine through said cut-0H valve or valves and a low-pressure coil or annular conduit inclosing said high-pressure coil and which is connected with and fed from said exhaust-chamber, said interchanger being located outside of said insulating-chambers, and arranged as an insulating-coil surrounding or inclosing said double insulatingchambers within its folds or coils and a gravity liquid-passage or protected conduit leading from said exhaust-chamber and passing through said vacuum-jacket, and delivering to a liquid-holding receptacle outside thereof, substantially as shown and described.

8. In a machine or apparatus for liquefying air, the combination of a compressed-air engine having an expansion-cylinder, provided with a piston having pressure-holding rings of very light tension so as to run in said cylinder without lubrication and with practically no friction, and also provided with a cut-off valve or valves and means for operating same, and with suitable connections for expanding air against resistance; double insulatingchambers substantially inclosing said engine, one of said chambers being an exhaust-chamber connected with the cylinderof said engine, and the other being a vacuum-chambcr; and a counter-current thermal interchanger consisting of a high-pressure coil or conduit connected with and delivering to said expansion-engine through said cut-off valve or valves and a low-pressure coil or annular conduit inclosing said highpressure coil and which is connected with and fed from said exhaust-chamber; said interchanger being located outside of said insulating-chambers, and arranged as an insulating-coil surrounding orinclosing said double insulating-chambers within its folds or coils, and two outlets from' said inner insulating-chamber,in form of protected passages or conduits passing through the outer one of said insulating-chambers, one a cold and expanded air or vapor outlet, delivering to the low-pressure coil of the thermal interchanger, and the other a gravity liquid-passage delivering to an outside liquid-holdingreceptacle, substantially as shown and described.

9. In a machine or apparatus for liquefying air the combination of a reciprocating expansion-engine, provided with a cut-off valve or valves and means for operating the same; double insulating-chambers substantially inclosing said engine, one of said chambers being an exhaust-chamber connected with the cylinder of said engine, and the other being a vacuum-chamber; and a counter-current thermal interchanger located outside of said insulating-chambers, said engine having a sleeve around the piston-rod of same,eXtending from the expansion-cylinder through said double insulating-chambers, and provided with a stuffing-box at the outer end thereof, and a drum containing calcium chlorid or other moisture-absorbing substance, for removing moisture from the air before delivering same to said engine, substantially asv shown and described.

10; In a machine or apparatus for liquefypansion-engine insulated from the heat of the outside atmosphere, and substantially inclosed by double insulating-chambers, one of said chambers being an exhaust-chamberconnected with the engine and the otheravacuum chamber, said engine having a sleeve ing air, the combination of a reciprocating ex-.

around the piston-rod, extendingfrom the expansion-cylinder through said double insulating-chambers with a stuffing-box at the outer end of same; an air-compressor having means for removing the heat of compression; a counter-current thermal interchanger, a

drying-drum containing calcium chlorid or other hygroscopic materials, havinga brine tank or trap attached to its lower end, and arranged to catch and trap the drip from said drum, said drying-drum and brine-trap and said interchanger being located outside of saidinsulating-chambers, between said expansion-engine and said air-compressor; and a compressed -air conduit connecting said compressor with and delivering to said engine, which conduit passes successively through said brine-trap and drying-drum and interchanger, and forms the high-pressure coil or conduit of said interchanger, substantially as shown and described.

11. In a machine or apparatus forliquefying air, the combination of a reciprocating expansion-engine insulated from the heat of the outside atmosphere, and substantially inclosed by double insulating-chambers, one of said chambers being an exhaust-chamber connected with said engine and the other a vacuum-chamber, said engine having a sleeve around the piston-rod, extending from the expansion-cylinder through said double insulating-chambers with a stuffing-box at the outer end of same; a counter-current thermal interchangerlocated outside of saidinsulatingchambers; said engine having a cutoff valve or valves and means for operating the same and for expanding against resistance compressed air therein; and a drying-drum containing calcium chlorid or other hygroscopic materials for absorbing moisture from the air, and having an air-purifying brine tank or trap attached toits lower end and connected therewith by a pipe or conduit, which passes from the upper end of said brine trap or tank into the bottom of said drying-drum, and so arranged to serve as a passage for compressed air to pass upwardly from said purifying-tank into said drum and also as a drain for the moisture absorbed from the compressed air and condensed therein to pass downwardly from said drum, so as to catch and trap the said condensed moisture in said brine-trap; said purifying-tank having a compressed-airinlet pipe near the bottom thereof, and said drying-drum having a compressed-air-outlet pipe at or near the top thereof, whereby compressed air is delivered first to said tank or trap through said inlet-pipe and is passed through the brine or purifying solution therein, and is then conducted into said dryingdrum through or in contact with said hygroscopic substance, and after giving up moisture thereto, is delivered to said outlet-pipe at or near the top of said drum, substantially as shown and described.

12. In a machine or apparatus for liquefying air, the combination of a reciprocating expansion-engine insulated from the heat of the outside atmosphere, and substantially inclosed by double insulating-chambers, one of said chambers being an exhaust-chamber connected with said engine and the other a vacuum-chamber, said engine having a sleeve around the piston-rod, extending from the I expansion-cylinder through said double in- 1 sulating-chamber with a stuffing-box at the outer end of same; and havinga cut-off valve or valves and means for operating the same and for expanding compressed air in said engine against resistance; a drying-drum containing calcium chlorid or other hygroscopic materials, and having an air-purifying brine tank or trap attached to its lower end and connected therewith by a pipe or conduit which passes from the upper end of said brine trap or tank into the bottom of said dryingdrum, and so arranged as to serve as a passage for compressed air to pass upwardly from said purifying-tank into said drum and also as a drain for the moisture absorbed from the compressed air and condensed therein to pass downwardly from said drum, so as to catch and trap the said condensed moisture in said brine-trap; and a counter-current thermal interchanger located outside of said insulating-chainbers, and comprising a highpressure or compressed-air conduit delivering to the cut-off-valve chamber of said engine, and which is connected at its inlet end with and fed from said drying-drum; and a low-pressure or expanded-air annular conduit iuclosing said high pressure conduit, and which is connected with and fed from the in snlated exhaust-air chamber of said engine, substantially as shown and described.

13. In a machine or apparatus for liquefying air, the combination of a compressed-air reciprocatingexpansion-engine provided with a cut-off inlet valve or valves and means for operating the same; with double insulatingchambers substantially inclosing said engine, comprising an insulating expanded-amenhaust chamber connected with said engine by exhaust-ports therefrom, and an insulating vacuum-chamber substantially surrounding or inclosing said expanded-air-exhaust chamber, and a counter-current thermal interchanger located outside of said insulatingchambers, said interchanger being arranged as an insulatingcoil, surrounding or inclosing said double insulating-chambers Within its folds or coils, and comprising a high-pressure coil or conduit connected with and delivering to said expansion-engine through said inlet cut-off valve or valves, and a lowpressure expanded-air coil or annular conduit inclosing said high-pressure coil, and which is connected with and fed from said insulating exhaust-chamber, substantially as shown and described.

Signed at New York, in the county of New York and State of New York, this 1st day of February, A. D. 1002.

JAMES F. PLACE.

Witnesses:

EneEWoRTH GREENE, CLARENCE PLACE.