US1969169A - Method of and apparatus for solidifying carbon dioxide - Google Patents

Description

T. EICHMANN Aug. 7, 1934.

METHOD OF AND APPARATUS FOR SOLIDIFYING CARBON DIOXIDE Filed May 1 .1952 2 Sheets-Sheet '1 COM PRE S S 0/? 4 VA. 1 o n .5 4M 5 1 5 5 R mm U M 6 MW V M/ 9 a GLIAIIL M Q m a 1 5 M 1 m v m W U R r I z p 6 0 a?! v 0 J M w J 4 I T. EICHMANN Aug. 7; 1934.

METHOD OF AND APPARATUS FOR SOLIDIFYING CARBON DIOXIDE Filed May 16, 1932 2 Sh ets-Sheet 2 QR M Patented Aug. 7, 1934 MIETHOD FYING CARB or AND arranarvs roa 80mmon nroxma Theophil Eichmann, Bern-Liebeleld, Switzerland, minor to International Carbonic Engineering Company, Kennett Square, Pa., a corporation of Delaware Application May 16,1932, Serial No. 811,741

Claims.

This invention relates to certain improvements, in the method of and apparatus for solidifying carbon dioxide; and the nature and objects of 5 the invention will be clearly recognized and understood by those skilled in the arts involved in the light of the following explanation and detailed description of the preferred method and steps thereof from among equivalent or other .10 steps within the scope of my invention, and the description of the accompanying drawings illustrating what I now believe to be the preferred embodiments or mechanical expressions of apparatus for carrying out the method, from among various other forms, arrangements, combinations, and constructions of which the invention is capable within the spirit and the scope thereof.

My present invention, in both method and apparatus, is primarily directed to substantially overcoming certain problems. and materially reducing and practically eliminating certain difllculties encountered in the use of mechanical or hydraulic and the like press apparatus for compressing previously solidified carbon dioxide into dense, coherent blocks or cakes of solid carbon dioxide having a sufficient structural strength for handling and transportation.

In accordance with a prevailing practice in the use of a press for forming blocks of solidified carbon dioxide, liquid carbon dioxide is expanded 3o abruptly down to substantially atmospheric pressures directly in the press chamber with the resulting freezing out and solidification of a portion thereof as loose dry snow, due to the temperature drop accompanying such expansion, and the gasification of the remainder of the liquid carbon dioxide, as will be familiar to those skilled in the art. The carbon dioxide gas formed in the press chamber during and by the snow formingexpansion of the liquid is drawn away at the required rate and in any suitable manner to maintain the substantially atmospheric pressures in the press chamber. After a sufficient or desired quantity of the loose and dry carbon dioxide snow is formed in the press chamber, expansion of the liquid is stopped and the press is then operated to compress and compact the loose snow into a dense block.

It is a main object of my present invention to materially improve upon the above outlined and similar practices utilizing a press, by the provision of a method, and a design and arrangement of press and associated apparatus, through the medium of which the time required to form F the completed blocks is greatly reduced and the production of the press over a given period of time thereby very materially increased; operating difficulties, maintenance, and cost of production are reduced; and the high quality and desired uniform density of the formed blocks is maintained with a minimum or production loss.

A further object of my inventionis the provision of an efficient form of liquid expansion valve and a relative mounting and location thereof on and with respect to the press chamber and the expansion gas outlet ports from the chamber, 65 for carrying out certain steps of the method of the invention.

With the foregoing general objects and results in view, as well as certain other objects, features and results which will be readily recognized from the following explanation, my invention consists in certain novel steps and their sequence forming my method, and in certain novel features in construction and combination of apparatus and elements thereof, all as will be more fully referred to and specified hereinafter.

Referring to the accompanying drawings, in which similar reference characters refer to corresponding elements throughout the several figures thereof:

Fig. 1 is a purely diagrammatic view of apparatus, including a press, embodying my invention and for carrying out the method thereof.

Fig. 2 is a more or less diagrammatic view, in vertical section through a press, portions of the press being broken away or not shown, and particularly showing the construction of the liquid expanding nozzle and valve and its relative mounting and location in the press.

Fig. 3 is a horizontal, axial section through the liquid nozzle and valve, taken as on the line 3-3, of Fig. 2.

Figs. 4, 5, and 6 are purely diagrammatic views of the press to indicate the various steps from the formation of the moist snow therein, to

. the compressing of the carbon dioxide ice block.

Fig. '7 is a view similar to Fig. 5 to diagrammatically show a modified press arrangement for carrying out a modification of the method of the invention. 1

A possible, and what I now believe to be a preferred, form of apparatus for carrying out the method of and embodying my invention, is more or less diagrammatically disclosed in Figs.

1 to 3, inclusive, of the accompanying drawings, 1 although apparatus incorporating the several features of the invention is not necessarily or in all respects limited to the particular forms and arrangements of the illustrated examples.

For instance, in Fig. 1, I have purely diagram- 1 10 3 arrangement of such a press P may be more or less conventional and it is not deemed necessary to here illustrate and describe the complete press structure and its operating and controlling mechanisms. except in so tar as such structure ber of the press and arrangement is modified and changed in accordance with my invention. 18

In Fig. 2. I have illustrated the press cham- P, which in the example hereof happens to be rectangular, in cross section, al-

lower end engages against and forms a sealing ilt with though not so limited. and is formed by the vertical walls 10. The upper end of the press chamber is closed by the vertically reciprocal plunger or piston 11 slidably fitting and received in the chamber between walls 10; plunger or piston 11 being provided with the usual D- wardly extending piston rod operatively associated with the usual hydraulic or other suitable plunger operating mechanism (not shown). The lower end of the press chamber is closed by a vertically movable plate or platform 14 which is carried on the upper end of a rod or column 15 actuated by suitable hydraulic or other mechanism 'of the usual type (not shown) to raise and lower platform 14 to and from press closing position. In position closing the of the press chamber, platform 14 the lower ends of pres walls 10; the arrange ment being such that the platform is held in closed position against the pressures exerted by piston 11 during the pressing operation. Upon completion of the pressing operation, platform 14 is lowered for removal of a block formed in the press.

New, in accordance with the principles or my invention, provision is made for expanding liquid carbon dioxide down to such a pressure as to form a moist, plastic carbon dioxide snow or slush ice together with carbon dioxide gas, and injecting or discharging such mixture directly into the press chamber. where it is collected until a desired quantity is formed therein; the

in the press chamber being maintained during such operation at that necessary to preserve the moist snow or slush'conditions of the mixture of liquid, solid and gaseous carbon dioxide, all as will be more fully explained hereinafter. For instance, in Figs 2 and 3 odvthe drawings 1 have illustrated in detail a form of liquid carbon dioxide expanding and moist snow forming valve and diffusing discharge nozzle unit V, which is mounted in and through a side wall 10 adjacent the upper end of the press chamber at a downward inclination so as to dis- 1 charge downwardly into and through the press chamber from the upper end thereof.

This valve and discharge nozzle unit'v comprises an elongated body member having the axial nozzle forming conical bore 21 extending from its outer discharge .end. inwardly to the restricted or reduced opening or port 22'which communicates with the enlarged liquid carbon dioxide supply bore or e '23. The pas- 'sage23extendslaterallyfromthebody20 a' side coupling member 24 which is suitably connected to a supply line from a source I: or dioxide. The discharge and expansionof the liquidcarbon dioxide through port 22 and into nozzle 21, is controlled by a needle type valve 25 which seats in port 22 to shut off discharge therethrough and which is controlled by a stem 26 extending axially through and is threaded at 27 in the bow 20. The stem 26 extends through a suitable packing gland member 28 at the outer end of body 20, and is provided with an operating hand wheel 29 at its outer end. By adjusting valve 25, the desired liquid expansion in the valve and diffusing nozzle is obtained.

The upper end of the press chamber, in proximity to but below the normal raised position of press plunger or piston 11, is provided with a series or plurality of carbon dioxide gas discharge ports 30. in the instant example there are provided one of said ports 30 in each of the press walls 10 except the wall 10 in which the valve and nozzle unit V is mounted- (see Fig. 1 in connection with Fig. 2).

Following the further teachings of my inverrtion. the press designed and arranged as set forth above, is operatively associated and arranged with certain other apparatus in order to carry out the method of the invention.- As an example of a system and cycle utilizing a single press providing v gas is compressed to a liquefying pressure, say,

moo-1025" lba, from any suitable source, and

supplies liquid carbon dioxide to any suitable receiver R by the supp y. line3l. This ,.-s'upply line is shown in Fig. 1 as broken and connecting the third or high pressure stage of compressor C with receiver R, and it is to be understood, of course, that the usual and conventional or other suitable arrangements of condenser, such as L. intercoolers, cleaners and'the like are interposed in line 31; it not being considered necessary here to disclose such conventional apparatus. The-receiver R is connected by a line 32 having-a valve 33 therein, to the expanding valve and diflusing nozzle unit V, line 32 being connected to coupling member 24 of unit V (see Fig. 3). Each of the gas discharge ports 30 of the press chamber is connected and discharges into a main gas line 34, by a pipe 35 which extends and returns gas from the press chamber to the first stage of compressor 0 for reliquefaction. A shut-off valve 36 is located in line 34 between the pipes 35 and compressor C. I

An auxiliary, supplemental or booster compressor C of the two-stage type is provided for compressing and reliquefying gas from the press chamber during certain periods or steps in the practicing of the method, and the second or high pressure stage of compressor C is connected, I

through the usual condensers, such as L', heat exchangers and the like. by line 37 with the receiver R for returning the liquid carbon dioxide to the receiver supply. The low pressure stage of compressor C is connected by line 38 with the line 34 at the opposite side-of gas lines 35, from that connected with compressor C, a valve 39 being interposed in line 38 between lines 35 and compressor C. v

The first step oi themethod of my-invention includesjthe expansion of the liquid carbon dioxide in the valve and diflusing nozzle unit. V, down to approximately the triple point pressure for carbon dioxide, that is,'a pressure or the order of '13-'79 lbs.. or between 5 and 6 atmospheres, say preferably at pressure of 5.28 atmospheres absolute. The desired approximate triple point pressure is obtained by adjusting valve 25 to the required extent of opening of port 22 to the diffusing nozzle 21. At the triple point pressure and corresponding temperature, carbon dioxide can and will exist as a liquid, a solid (frozen), and a gas, so that, when the liquid is expanded in the valve'and nozzle unit V of my press. P, down to approximately the triple .point, the liquid is formed partly into frozen or solid form, partly into gaseous or vapor form, and a part remains as liquid, with the result that a moist, plastic snow or slush, together with gas or vapor is formed .and discharged directly into the press chamber by and through the velocity decreasing'fdii'fusing nozzle 21. The nozzle 21 is downwardly inclined in the press and so the moist snow'and gas, under the decreasing velocity caused by conical bore 21, are injected or discharged downwardly to the lower end of the press with the moist snow collecting in the lower end and the gas separating out and collecting in the upper end above the moist mass, for withdrawal through ports 30 (see Fig. 4).

Now during the expansion and discharge into the press chamber from unit V, the valve 36 in line 34 to compressor C is shut and valve 39 in line 38 to compressor C is open, so that the gaseous carbon dioxide is withdrawn from the press chamber through lines 35, '34, and 38, by compressor C to its first stage. the rate of withdrawal and capacity of the gas ports 30 and lines to the compressor being such as to maintain approximately triple point or moist snow preserving pressures, say of the order of 5.28 atmospheres, in the press chamber. Fig. 4 of the drawings diagrammatically illustrates these first steps of my method, in which the gas is withdrawn by compressor C from the press chamber above the forming mass of moist snow or slush, to maintain substantially triple point or moist snow preserving pressures, as the liquid is expanded in and discharged as moist snow and gas from. the valve and difiusing nozzle unit V, during the formation and .collection of such moist snow in the lower end of the press chamber.

when the desired quantity of moist snow or slush is formed and collected in the press chamber by the foregoing steps of the method (the quantity can be determined by timing), the next step, referring now to Fig. 5 in connection with Fig. 1, includes cutting of and stopping liquid expansion by closing valve 33 in the liquid line 32, closing valve 39 to shut-oi! withdrawal of gas at triple point pressures by compressor 0', and opening valve 38 for withdrawal of the remaining gas and reduction of the pressure in the press chamber down to atmospheric by the compressor C. The operation of compressor C withdraws gas remaining in the press chamber (see Fig. 5) and reduces the chamber from approximately the triple point, or whatever higher final pressures may have been employed where found desirable to drench or increase the liquid content just prior to stopping liquid expansion. down to atmospheric pressures. This final pressure reduction in the press chamber causes expansion of a-portion of the liquid particles forming themoist snow, with a freezing of the remainder due to the lowering of the temperature down to approximately C., the expansion gases difiusing upwardly through the mass as indicated by the arrows in Fig. 5, and a resulting freezing and congealing tially compacted ice mass of the mass into solidified relatively high density ice form. That is, by the foregoing step, there is produced from the mass of moist or wet snow an already partially compacted, coherent and sub stantially dense body of solid carbon dioxide in so the press chamber. v

After the solidified substantially dense and paris formed in the press chamber, valve 38 to compressor C is closed (valve 39 to compressor C remaining closed) and the press plunger or piston 11 is then actuated, as indicated in Fig. 5, to move downwardly to apply the required pressures to the ice mass to compressthe same into a block or cake of ice of the desired higher density; the resulting density of the block being of course dependent upon the pressure and the duration thereof, appplied to the ice mass. However, due to the partially compacted and already substantially dense character of the body of carbon dioxide solidified from the moist snow, the pressing operation as compared for example with that required for the compacting of a mass of loose dry snow or crystals to the same density, is accomplished either orboth by the exertion of a smaller or lower order of mechanical pressure, or the exertion of an equal mechanical pressure for a shorter duration. v The term "high density is recognized by those skilled in this art. .when applied to solid carbon dioxide, as a specific gravity 0! upward of 1.4. Upon completion of the pressing operation the block formed is then removed by opening the lower end of the press through lowering platform 14, after which the press can be again closed and the above described cycle of the method repeated to produce no another block.

A modified arrangement of a press P is disclosed in Fig. 8, more or less diagrammatically, in which the expansion gases are withdrawn by compressor C not only from above the mass of 1 moist snow, but also from the lower end of the press chamber through an outlet or outlets 30'. so that there is a downward difiusion through the mass of some of the gases from the liquid as the pressure in the chamber is reduced. For inno stance, in the operation of the press of Fig. 8, during moist snow formation at triple point pressures, outlet 30' is closed by thesvalve 50 in line 51 which connects with compressor C, valve 52 also being closed, so that gas ls withdrawn by 2 compressor C through line 35 and open valve 39. Then upon completion of the moist snow forming operation, valve 39 is closed and valve 50 opened for gas withdrawal and pressure reduction by compressor C from the lower end of the press In chamber through port 30' and line 51; or if desired valve 52 can be opened so that gaswithdrawal takes place from both the upper and lower ends of the press chamber.

By the arrangement of press and associated ap- 5 paratus of the invention carrying out my method. in actual operation of a press with a production capacity of from 5 to 8 tons per day, when operated by prior practices. the actual production was increased to 12 to 13 tons per day, while the requiredpower consumption per ton of ice produced was decreased. Further, the serious gas discharge port stoppages encountered with prior practices were eliminated and continuous and efiicient press operation obtained with a lowcost production of high quality and uniform density ice blocks.

While I have disclosed-in the specific examples hereof, of the vertical types, my invention is not so limited, but contemplates and in- 9 eludes, where desired or found expedient, the adaptation to and utilization of presses of the horizontal types.

It is also evident that various changes, modisliding fit with the walls of said chamber: a liq-- uid carbon dioxide expansion valve and expanding bore velocity decreasing nozzle mounted in a side wallof said chamber at the upper end thereof inproximity to but below the normal raised position of the plunger with the nozzle discharging directly into the chamber at a downward inclination, and said chamber formed with an expansion gas outlet through the side thereof in proximity to but below the normal raised position of saidplunger at the upper end of the chamber.

2. A method of producing solid carbon dioxide, including the steps of expanding liquid carbon dioxide to approximately the triple point pressure to form moist snow and gases therefrom and discharging the moist snow and gases into a chamber; withdrawing the gases from the chamber and maintaining the chamber pressure during discharge and collection of the moist snow therein at a pressure to preserve the moist snow; then reducing the chamber pressure to evaporate part of the liquid in the moist snow to solidify the mixture in the chamber into a mass of substantially coherent and dense solid carbon dioxide; and applying mechanical pressures of a low order for a short period of time necessary to complete the mass in the chamber into a block of solid carbon dioxide of high density.

3. A method of producing solid carbon dioxide,

pressure actuated plunger therein; withdrawing the gases from the chamber and maintaining the chamber pressure during discharge and collection of the moist snow therein at substantially the triple point pressure; stopping discharge of moist snow and gases from the nozzle; reducing the chamber pressure to evaporate and solidify a portion of the liquid in the moist snow to convert the mixture in the chamber to a partially coherent and compacted body of solid carbon dioxide: and applying pressures of a low order to the body of solid carbon dioxide by a stroke of said plunger of a short duration as required to complete the body into a block of solid carbon dioxide of higlr density.

4. A method of producing solid carbon dioxide, including the steps of expanding liquid carbon dioxide to approximately the triple point pressure to form-moist snow and gases therefrom;

discharging the moist snow and gases into a chamber; withdrawing gases from the chamber during discharge and collection of the moist snow therein from above the collected mass of snow and maintaining a moist snow preserving pressure in the chamber; stopping discharge of moist snow into the chamber; reducing the chamber pressure by withdrawing gases from the chamber above the mass of moist snow therein to evaporate a part of the liquid in the moist snow to solidify the mass into a body of partially coherent and dense solid carbon dioxide; and applying pressures of a low order to the solid carbon dioxide bodyrrequircd to complete the same into a block of solid carbon dioxide of high density.

5. A method of producing solid carbon dioxide, including the steps of forming and discharging a mixture of liquid and solid carbon dioxide into a chamber and collecting a mass of such mixture therein: maintaining the chamber pressure during discharge and collection of the mixture therein at a liquid preserving pressure; stopping discharge of the liquid and solid mixture into the chamber; reducing the chamber pressure to a pressure to evaporate a part of the liquid in the mixture to solidify the mixture into a body of partially coherent, dense solid carbon dioxide; and completing the body of solid carbon dioxide so formed by applying thereto pressures of a low order necessary to form the same. into a block of solid carbon dioxide of high density.

THEOPHIL EICHMANN.

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