US2047099A - Method and apparatus for freezing liquid carbon dioxide - Google Patents

Description

*g g E 4 w 3 4 50 y 1936- J. c. GOOSMANN v 2,047,099

METHOD AND APPARATUS FOR FREEZING LIQUID CARBON DIOXIDE Filed Oct. 24, 1928 3 Sheets-Sheet 1 anbmtoz LES/0.5. G Gtws'mann Juli 7 1936- .1. c. G-OOSMANN METHOD A'ND APPARATUS FOR FREEZING LIQUID CARBON DIOXIDE Filed Oct. 24, 1928 s Sheets-Sheet 2 532g mEo 38k $539k smahn 115+ C. Goo 835 /7/6 Wi ma/mugs 3 y 1936. D J. c1 GOOSMANN V 2,047,099

METHOD AND APPARATUS FOR FREEZING LIQUID CARBDN DIOXIDE Filed Oct. 24, 1928 3 Sheets-Sheet 45 M 1- M RH /04 1 /08 I Irma/2 loo /O/ vwwtoz cjz'sfus GODS/nan 3251 hwQbtoz mqs samurai 1, 1936 2,041.0 I rnrrnon m manarus ron mazzmc.

LIQUID CARBON DIOXIDE Justus C. Goosmann. Chicago, 111.. assignor. by

mean assignments. to Adico Development Corporation fl n e 24, 1928. Serial Names I (01. 02-121 This invention relates general to apparatus and a method used in connection therewith for freezing liquid carbon dioxide into solid form.

One of the objects of this invention is the pro- 5 vision of an apparatus and a method for use in connection therewith which are relatively sim ple and yet highly efllcient in use.

A further object of this invention is the provision of a system in which carbon dioxide gas is placed under high pressure in several stages oi compression and in which the gas is cooled after each compression operation by a counter-flow oil cooler gas from another part of the system. A further object oi this invention consists in the reduction in pressure of the gas alter its delivery from the last compression operation in several stages of pressure reduction in'whlch the gas flows from a liquid receiver and several liquid coolers in succession.

Another object of this invention is to provide a liquid cooler in which the llquid carbon dioxide is cooled by external evaporation of a. portion of the liquid carbon dioxide and heat transfer through the intervening walls of the cooler while at the same time maintaining a higher pressure.

of the liquid which thus becomes sub-cooled below the pressure at which it is maintained whereby any gaseous bubbles in the liquid will be condensed and liquefied.

- A still further object of this invention contemplates the delivery of the liquid from the last liquidcooler to a freezing machine under such conditions of temperature and pressure that the liquid is maintained ina liquid state.

' A further object of this invention contemplates templates a sudden reduction in pressure in the freezing machine after sufficient liquid is delivered thereto to eiiectfreezing of the liquid.

45 Another object of this invention is the provision of a liquid freezing machine of a construction which is relatively simple and adapted for efflcient and rapid use in effecting the freezing of liquid carbon dioxide.

'50 A still further object of this invention is the provision of means in connection with the freezing machine whereby the frozen block of carbon dioxide may be readily removed therefrom.

A- stillfurther object'of this invention involves 55 the use-of pressure reducing valves in dlflerent parts of the system for effecting the desired rc- (motions in pressure as the gas and liquid progresses therethrough.

These and other objects, as will appear from the following disclosure. are secured by means oi this 5 invention.

This invention resides substantially in the combination, construction, arrangement, relative location of parts, steps and combinations of steps, all as will more fully appear in the following dis- 10 closure when taken in connection with the drawings and set forth in the appended claims.

Referring to the drawings for illustrated ex-' amples of the principles and structures involved in this invention, 15

Figure 1 is a diagrammatic view with some parts in cross section showing the general combination of elements comprising the system of this invention and employing the process thereof;

Fig. 2 is a vertical cross-sectional view through 20 the freezing machine showing the relative association of all the parts; I

Fig. 3'is a vertical cross-sectional view of one form of pressure reducing valve adapted for use in the system of this invention; 25 Fig. 4 is a longitudinal cross-sectional view through one form of liquid cooler; inter-cooler or heat exchangers adapted for use in the system of this invention; and Fig. 5 is a cross-sectional view through one of 3 the mixing chambers.

.The general considerations underlying the operation and use of a system of the type of this invention, as well as the principles of operation and physical philosophy underlying its use have 35 been disclosed in considerable detail in my copending application, Serial No. 298,992 filed August 11, 1928. It seems, therefore, unnecessary to set forth these considerations in detail in this application except such departures there- 40 from and additions thereto which are peculiar to the operation of this apparatus. These considerations will be discussed in connection with the disclosure of the apparatus in detail and the operation thereof.

The general distinction in this procedure lies in the fact that instead of forming the liquid carbon dioxide into snow and then compressing it into blocks the liquid is frozen directly into solid form by means of a liquid freezing machine rather than a snow forming machine.

Referring now to the drawings there is disclosed at l a pipe leading from any suitable source of carbon dioxide gas through whlch'the warm gas at approximately 5 pounds gauge presliquid cooler 3| through pipe 29 in which is the second pressure reducing valve which efiects a sure and a temperature of approximately F. is delivered to the mixing cylinder 2. The mixing cylinder consists simply of a closed chamber as do the other mixing cylinders to be mentioned and described later. A pipe 3 connects the mixing cylinder with the first compressor comprising a cylinder 4 and piston 5. This compressor, like the other compressors to be mentioned later, presents the ordinary type of compressor having two opposed valves as indicated in the drawings, one of which (the left-hand valve) opens on the suction stroke of the piston (downwardly in Fig. l) and the other (the righthand valve) opens on the compression stroke of the piston (upwardly in Fig. 1) causing a compression of the gas and its delivery to pipe 6.

As is well understood, only one of these valves is open at a time and are so adjusted that the first compressor compresses the gas to a pressure of approximatelylOO to 150 pounds pressure and a temperature of approximately 150 which is subsequently reduced in the inter-cooler I and by the admixture of colder gas in the mixer 9 returning from other points in the system. The gas then flows from pipe 6 through the first inter-cooler 1. This inter-cooler comprises a pipe coil immersed in cold water, or it may have the form shown in Fig. 4 so arranged that cold water may flow thereover.

Liquid CO2 may be used for cooling instead of water by external operation as for instance in liquid coolers 28 and 3|. Other suitable cooling means may also be used. The gas is then cooled to approximately 80 F. and flows through pipe 8 to the mixing chamber 9 where it is further cooled to about 30 by the cold gas entering the mixer through pipes 46 and 49. From this mixing cylinder the gas flows into cylinder H of the second compressor through pipe l0, Piston |2 compresses the gas to a pressure of approximately 350 to 450 pounds gauge from whence it is delivered through pipe I 3 to the second inter-cooler l4," in which its temperature is again reduced to about 30 by cold gas entering the mixer l8 through pipes 45 and IT. The gas then flows through pipe l5 to coll I6 of the heat exchanger 43. The gas is cooled still further in coil l6 and then delivered to the third mixing cylinder |8 through pipe Pipe ill-connects cylinder l8 with the third compressor 20 where the gas is compressed by piston 2| to approximately a pressure of 1000 pounds gauge and a temperature of 140 to 150 F. This gas is then delivered through pipe 22 to the condenser coil 23 where it is sufiiciently cooled to change it into a liquid as it flows through the connection having the control valve 24 to the liquid receiver 25. This liquid is then delivered at a temperature of approximately 80. through pipe 26 to the first liquid cooler 28 through the pressure reducing valve 21. This valve is of the type shown in Fig. 3 and will be described in detail later. This valve efiects a reduction in pressure of from approximately 900 to 1000 pounds gauge to approximately 350 to 400 pounds gauge whereby its temperature is automatically reduced to about +10. The liquid is then delivered to the second reduction in pressure of from, approximately 350 to 400 pounds gauge and a corresponding temperature to a pressure of about 150 pounds and a temperature around -40 F.

During the operation of reducing the pressure of the liquid as it flows from cylinder 25 to cylinder 28 some gas is formed which is delivered through pipe 45 to mixing cylinder l8 where it mixes with the warmer gas coming from the second compressor and as a result cools it. It is the cooled mixture flowing from mixing cylinder l8 which is compressed in the third compressor. A connection 46 extends from cylinder 3| and conducts the gas formed in the pressure reduction effected by valve 30 to mixing cylinder 9 where the relatively cooler gas mixes with the relatively warmer gas coming from the first compressor. It is this mixture of gases which is compressed by the second compressor. The cooled liquid fiows from cylinder 3| through pipe 32 in which is the pressure reducing valve 33 to the liquid freezing machine 35. The liquid in passing through valve 33 is reduced from a pressure of approximately 150 pounds gauge to 60 pounds gauge and an equivalent temperature of approximately -70 F. For liquid carbon dioxide 8. pressure of 60 pounds gauge and a temperature of -'70 F. represents the critical temperature of the liquid at which. or below which, the liquid automatically-changes into the solid phase. The liquid may also be cooled by external evaporation and heat transfer through a metallic wall.

However, in order to prevent the premature reduction in pressure and temperature of the liquid as it flows into the liquid freezing machine it is necessary to build up a pressure within the machine before the liquid is delivered thereto. This is eifected through pipe and valve 9| which leads into the interior of the machine and through which carbon dioxide gas may 35 be introduced from any suitable source, for instance, from pipe 46 as shown, so that the pressure within the machine may be built up to approximately 150 pounds gauge.

Since the pressure in cylinder 3| is at approximately from 150- pounds upward gauge valve 9| can be a pressure reducing valve which effects a reduction of pressure in the gas to'approximately pounds gauge so that the pressure within the liquid freezing machine will not be built up above that amount. A pipe 49 having the valve 50 therein connects the liquid freezing machine with the mixing cylinder 8. Valve 50 may be of the type shown in Fig. 3 and acts in this case as a sort of a check-valve as will be described in detail later. Pipe 41 and its valve 48, which is an ordinary valve, is connected to any suitable point in the system, as for example to pipe |5, so that warm gas may be delivered to the liquid freezing machine for a purpose to be disclosed later. Pipe 38 having the valves 39 and 40, which are ordinary control valves or quick acting valves, connect the freezing machine through valve 42 and pipe 4| with the heat exchanger 43 or directly to low pressure mixer 2 through pipe 4| for a purpose to be disclosed later.

The liquid freezing machine will now be disclosed in detail referring particularly to Fig. 2. The machine is shown comprising a casing 51 having an innerconically formed wall 5| united at its top with the top of the casing 5| and likewise at the bottom, as indicated at 53. The top of casing 5| is provided with a number of openlugs 52. Pipe 32, which extends into the casing within the inner wall, 'is provided with a suitably formed branch 58 having openings at the ends so that the liquid as it flows through these openings will fall onto the sides of wall 5| and flow downwardly without creating too much agitation thereof. As clearly shown, pipes 80 and 49 exindication of the height of theliquid within the machine.

The lower end of the casing is normally open and is adapted to be closed by means of a removable cover 31 and hinged bolts 56 by means of I which a tight seal may be iormed in conjunction with the gasket or washer '55. The top and 1 sides of the machine are covered with a heat in- ,sulating casing 54 of any suitable material, such as hair felt for instance. I a

The construction of the pressure reducing valve is shown in Fig. 3 and comprises a body member Gil having a passage ti and a passage 62 separated from each other by means of a valve. A removable cover member 63 is attached to the casing and is provided with a hollow extension which is threadedly engaged by means of the tube til having a cap attached to its upper rim by means of threads. A threaded rod and hand wheel t8 extends through the cap 55 and contacts with the member ti engaging the upper end of spring 88. The lower end of spring fit rests upon a disc 69 which is, in turn, supported by a flexible diaphragm rigidly held at its per'iphery between the members Eli and t3. Diaphragm it rests upon a button it slidably mounted in a member H which is threadedly supi of the stem and hand wheel 65. In each case in which the valve is used the high pressure connection is made to passage 62. The gas or liquid then flows into the upper chamber to which passage 52 is connected and through the small openings it in member II where it is stopped by manner. . Valves 21, 30,33, 99 and it all operate in this manner. Valve till is of the same construction but is intended to operate not only as a pressure reducing valve but also as a sort of check-valve.

- Theheat exchanger shown in Fig. 4 isadapted for use as an inter-cooler orliquid cooler. It is shown comprising a cylindrical casing I00 having an inlet and an outlet Iili and 102. The casing is provided with the removable heads H03 and Hi5 pr'ovidedwith connections Iilland Intrespectively Near each end of the casingis a transverse wall which support between them the pipes, I08 opening therethrough toestablishcomflmunication between the chamberat eachend'oi theicasingr At'the iowest'point ret ement 9. 1 drain valve'is provided; Whenthe device is'used as an inter-cooler, the cooling fluid passes through pipes I08 and the gas travels through the shell pipe 38 without permitting ,the escape of the liqaround the pipes. when usedas a liquid cooler, the liquid to be cooled passes through the tubes 108, either in parallel or in series, while the cooling medium as evaporating liquid CO2 passes through the shell around the tubes or it may be 5 reversed to suit conditions. The ,drain valve acts to remove water, oil or other impurities.

. The mixing cylinders can be of the construction shown in Fig. 5' and made of large extra heavy pipe. The mixing cylinder 9 is shown 10 having the pipe connections 8, i0, 46 and 49. A

drain valve, as before, is provided to remove water, oil and other impurities. Special separators and filters may be added to the pipe system to remove traces of oil, water and other impurities. 15

When liquid CO2 is employed in the heat exchanger, it may be so arranged that the liquid is cooled by external evaporation of CO2 reducing its temperature, while at the same time maintaining its higher pressure. The liquid CO: evaporatedby this method of liquid cooling may be returned to the corresponding mixer in the same manner and at the same pressure which applies when the liquid is cooled by the evaporation'of a part of-the liquid in the said container. 25

In this way the economy of the process is practically maintained without a change in pressure.

The operation of the device will now be given. The operation to the point where the liquid is delivered to cylinder 3i has already been given in detail in connection with the description of the apparatus. With valve (it closed, gas is delivered through pipe 96 to the liquid freezing machine until the pressure within it is built up to apprbximately 100 pounds gauge. Valve 34 is then opened and liquid is delivered from cylinder 3! into the machine against the pressure within the machine at sufllcient pressure to cause the gas to flow out through pipe 49, it being understood that valves 39, 40, and 48 areclosed. Valve 33 is set so thatthe liquid at a reduced pressure isdelivered to the machine at a pressure sufficient to overcome the pressure of the gas within the machine. It is, of course, apparent that if necessary or desirable the pressure within the machine may be varied at will. Valve 50 is so set that the pressure" of the liquid coming into the liquid freezing machine is suflicient to permit the escape of the gas within the machine through valve 50. This valve should also be set with a view to having the pressure of the gas at the proper value for delivery to mixing cylinder 9. When sumcient liquid has been delivered to themachine, as indicated by the sight glass 36, valve 34 isclosed.

Valves 39 and M1 are. then opened and the pressure within the machine is suddenly reduced far below the critical pointof .60 pounds gaugeand F. Valve lfl' is, preferably of thefjquick opening and closing type so as to deliver vthegas through pipe. ll lite; the heat exchanger 43 at the proper pressurei'or when desirable through pipe M for a sudden pressure dro p. In view;of the construction of the machine as disclosed itis ap-- parent thatthe gas therein can escapethrough uid which is confinedlwithin. the 'inner wall 5|.- The sudden reduction in pressure and tempera- "tiireto or. below'ithecritical values permits .or

causes the liquid, to flashintoits solid condition. 70 When; the liquid has solidified, valve ,34 .wbeing closed, cover 3] maybejremovedg If thesolidi-;;; fied carbondioxide sticks towall 5| a little warm gas may be sent through pipe 41 to warm wall 5| so that the solid block is loosened and ialls out 7 by reason of the conical shape of wall 5|. The device is thenready for a repetition of the above procedure.

One highly important function of the pressure reducing valve in each case is to prevent the depletion of gas or liquid from the source from which it is flowing to the valve. Thus when the pressure of the gas or liquid falls below a predetermined value spring 68 will effect the closing of valve M so that the source cannot be depleted below a certain predetermined value.

One of the very important features of the process and the apparatus for carrying it out involves the idea of suddenly dropping the pressure in the ice forming machine to a complete and rapid solidification of the CO: therein.

I am. of course, well aware that many details are subject to change without departing from the scope and principles of this invention and I do not, therefore, desire to be strictly limited to the specific illustrations given in the drawings and specification for purposes of illustration and demaintaining the gas under such pressure and temperature as to liquefy it, means for-gradually reducing the pressure and temperature of the liquid, including pressure reducing valves adapted to maintain a predetermined pressure in said.- means for gradually reducing the pressure and temperature of the liquid, means connected to said means for gradually reducing the temperature and pressure for receiving the liquid under a pressure and temperatureabove the triple point of the liquid, and means for reducing the pressure and temperature of the body of liquid in said receiving means below their critical values to effect solidification of the body of liquid therein. 2. In an apparatus of the class described, the combination comprising means for subjecting and maintaining the gas under such pressure and temperature as to liquefy it, means for reducing the pressure and temperature of the liquid to cool the same, including a pressure reducing valve adapted to maintain a predetermined pressure in said means, solidifying means for receiving the cooled liquid from said pressure and temperature reducing-means at a liquid sustaining pressure, and means for suddenly reducing the pressure and temperature on the body of liquid in said solidifying means below their critical values to effect solidificationof the body of liquid.

3. In an apparatus for solidifying gases, the combination comprising a plurality of compressors, connections between each compressor, a cooling coil and mixing cylinder in the connections between the first and second compressor and the second and third compressor, means connected to the third compressor for causing the compressed gas to liquefy, a series of tanks connected to said means having connections therebetween including pressure reducing valves, said pressure reducing valves maintaining the pressure in the last tank at a liquid sustaining pressure, connections between said mixing cylinders for returning gas to the latter, and a solidifier connected in the last tank for receiving liquid therefrom, said solidifier including means for maintaining a liquefying pressure therein for charging of the solidifier with a body of liquid from said last tank.

4. In apparatus for solidifying gases, the combination comprising a plurality of compressors, connections between each compressor including a cooling coil and means connected to the last compressor for causing the compressed gas to liquefy, a plurality of tanks connected to said means, said tanks having pressure reducing connections therebetween, connections from said tanks to said mixing cylinders for returning gas from the tanks to the cylinders, a solidifier including a solidification chamber therewithin connected with and receiving liquid from the last of said plurality of tanks, a connection between the chamber of said solidifier and one of said mixing cylinders for returning gas from the solidifier to the cylinder, and means in said connection for maintaining a pressure in said solidification chamber to enable from the solidification chamber of said solidifier to an intermediate stage of said multi-stage compression means for maintaining in the solidification chamber a liquid sustaining pressure whereby the chamber can be charged with a body of liquid, and means for releasing the liquid sustaining pressure in said solidification chamber to cause evaporation of the body. of liquid therein with resultant solidification of a portion thereof.

6. In apparatus for solidifying carbon dioxide and the like, multi-stage compression means for compressing carbon dioxide gas to a pressure at which it will liquefy, means for condensing the compressed gas to liquefy it, a carbon dioxide solidifier having a solidification chamber therein for receiving liquid carbon dioxide from said condensing means, means interposed between the condensing means and the solidifier for reducing the pressure of the liquid to lower its temperature, connections between said pressure reducing means and the multi-stage compression means for returning the cold gases from the pressure reducing means to the compression means, an expansion gas oiltake from the solidification chamber to said compression means, a valve in said connection for maintaining a pressure in the solidification chamber at which such chamber can be charged with liquid carbon dioxide, and

means for releasing the pressure on a charge 01 liquid carbon dioxide in the solidification chamber to evaporate the liquid and freeze out a portion thereof to solid; form, said means returning the expansion gases from the solidification cham- Tit;

a body of the reduced pressure and temperature liquid carbon dioxide in a closed chamber while maintaining a liquid sustaining pressure in such chamber by withdrawing gas from the chamber to an appropriate compression stage, and after charging the chamber with a body of liquid carbon dioxide reducing the liquid sustaining pressure in the chamber to cause the liquid to evaporate and freeze out a portion thereof as a solid by withdrawing the evaporation gases to the low pressure compression stage.

8. In apparatus for solidifying carbon dioxide the combination comprising means for compressing and liquefying carbon dioxide, a plurality of receivers connected to said liquefying means to receive liquid carbon dioxide therefrom, connections between said receivers, means associated with said receivers for efiecting a pressure and temperature reduction on the liquid in each receiver, said means adapted to prevent reduction of pressure below a liquid sustaining pressure, a carbon dioxide solidifier having a solidification chamber connected with and receiving liquid from the last of said receivers, a gas ofitake connection between the solidification chamber of said solidifier connected with said carbon dioxide gas compressing means to maintain a pressure in the chamber at which the chamber can be charged with a body of liquid carbon dioxide, and means for releasing the liquid carbon dioxide sustaining pressure in the solidification chamber after the latter has been charged with liquid whereby the liquid is evaporated to freeze out a portion, thereof as a solid, said pressure releasing means withdrawing the evaporation gas from the solidification chamber for return to the compression and liquefying means.

9. In apparatus for solidifying a gas, the combination comprising,.means for compressing and liquefying the gas, a receiver connected with said gas liquefying means to-receive liquid therefrom, means associated with said receiver for effectin a pressure and temperature reduction on the liquid in the receiver, said means adapted to pre-v vent reduction of pressure below a liquid sustaining pressure, a solidifier having a solidification chamber connectedwith and adapted to receive liquid from said receiver, a gas offtake between the solidification chamber of the solidifier and said gas compressing means to maintain a pressure in the chamber at which the chamber can be charged with a body of liquefied gas, means for releasing the liquid sustaining pressure in the solidification chamber after the latter has been charged with a body of liquid whereby the liquid is evaporated to freeze out a portion thereof as solidified gas, and said pressure releasing means providing for withdrawal of the evaporation gas from the solidification chamber for return to the gas compressing and liquefying means.

10. In apparatus for solidifying a gas, in combination mcans for compressing and liquefying the gas, means for reducing the pressure and temperature of the liquefied gas to cool the same, gas solidifying means for receiving and holding a charge of the cooled liquid from said pressure and temperature reducing means at a liquid sustaining pressure, and means for reducing the pressure and temperature of a charge of liquid held in the solidifying means below their critical values to effect solidification of the charge of liquid.

'11. In apparatus for solidifying a gas, the combination including means for compressing and liquefying the gas, areceiver connected with said gas liquefying means, means associated with said receiver for efiecting a pressure and temperature reduction on the liquefied gas in the receiver, said means adapted to preventreduction of the pressure below a liquid sustaining pressure in the receiver, a normally closed and gas-tight solidification chamber adapted to be charged with liquefied gas from the receiver, means connecting the receiver with the solidification chamber for discharging evaporation gas from the receiver into the solidification chamber to build up a liquid sustaining pressure in the chamber prior to charging the chamber with liquefied gas from the receiver, a gas ofltake between the solidification chamber and said gas compressing means for maintaining the liquid sustaining pressure in the chamber during charging with liquefied gas, and means for releasing the liquid sustaining pressure in the solidification chamber after the latter has been charged with liquid whereby the liquefied gas is evaporated to freeze out a portion thereof as solidified gas.

12. In gas solidifying apparatus, in combination, a source of liquefied gas, means for reducing the pressure and temperature of the liquefied gas from said source to cool the same, including a pressure reducing valve adapted to maintain a predetermined liquid sustaining pressure in said with a body of cooled liquefied gas from said means at a liquid sustaining pressure in said chamber, means placing said chamber in communication with said pressure and temperature reducing means for discharge of evaporation gas into the chamber to build up a liquid sustaining pressure therein prior to charging the chamber with liquefied gas, and means for reducing the means, a gas solidification chamber for charging pressure and temperature on a body of liquefied gas in the solidification chamber below their critical values to thereby eifect solidification of the body of liquefied gas in the chamber.

13. The method of solidifying carbon dioxide, including the steps of subjecting carbon dioxide gas to pressure and temperature conditions to liquefy the gas; reducing the pressure and temperature'of the liquefied gas to near the triple point of carbon dioxide; confining a body of the reduced pressure and temperature liquefied gas in i a gas-tight chamber at substantially such near triple point pressure and temperature; and then reducing the pressure on the body of. liquefied gas in the chamber to below the triple point while withdrawing the evaporation gases therefrom to freeze out a portion of the body of liquid as a mass of solidified carbon dioxide in the chamber.

14. The method of solidifying carbon dioxide, including the stepsof; subjecting carbon dioxide gas to pressure and temperature conditions toliquefy the gas; reducing the pressure and temperature of the liquefied gas to near the triple point of carbon dioxide by expanding the liquefled gas in a closed container while withdrawing the evaporation gas to maintain the predetermined liquid sustaining pressure in the container; charging a gas-tight chamber with the reduced pressure and temperature gas from said container while maintaining the liquid sustaining pressure in such chamber; and reducing the pressure on the body of liquid in such chamber to below the triple point totreeze out a portion of the liquid as a mass of solidified carbon dioxide.

M81708 0. GOOBMANN.

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