US1644338A - Discharging carbon dioxide - Google Patents

Description

C. L-. JONES DISCHARGING CARBODi DIOXIDE Oct. 4, 1927. ,6

. F'ilegi March 31, 1925 /0 INVENTOR L. QM

Patented Oct. 4, 1.927. t

UNITED STATES CHARLES IL. JONES, F PITTSBURGH, PENNSYLVANIA.

'mscmncme cannon moxnm.

the gas is discharged from its state of very high pressure in the tank the boiling of the liquefied gas and its great expansion produce low temperatures until some .of the gas or liquid congeals to form carbon dioxide snow. The temperature of this snow is about '110", Fahrenheit; If any water is present the water will freeze at a much higher temperature. In either case the system becomes clogged with solid products of this'freezing action and the flow of carbon dioxide is ma- I terially lessened hr altogether stopped.

I provide for handling the liquefied gas through a piping system having a non-unig form passage dimension as? contrasted with the system shown in the Rustige Patent, No. 1,335,394. This patent shows a liquid transportingsystem having a substantially uniform passage dimension so'that the pressure drop is evenly distributed along a pipe leadingfrom the bottom'ofaa carbon dioxide cylinder to the point of application to the fire or other place wherethe'gas is used. In the application of this system the piping'becomes ihtenselycold and ,is thereby subject to stoppage if very lar geramounts of lique- 4 fied gas are discharged through it. I provide a system :nofimniform pas-' sage dimensiengt he'conduit being relatively laygeand terminating in an orifice whichissmall enough to'loea-lize most of the pressure drop and hence most ofthe expansion at the orifice.

depends on the resistance to flow in the passage leading thereto. Obviously, the smaller the orifice the greater the pressure immediatelybBlllIlCl it, other cdnditions being equal, and I regard it as sound practice to proportion the systemso that the'pressure drop from the cylinder to the orifice will not exceed 100 lbs. per square inch under normal temperature conditions. v For example,

3 Application filed fiarch 81 1925. Serial No. 19,562,

the pressure in'a-cylinder of liquefied carbon dioxide at Fahrenheit 1sapproXi-f mately 7 50 lbs. per square inch, and I would use a iping system leading to the orifice or ori ces so large that the pressure just behind the orifice would'be 650 lbs. per square inch or more, the expansion from 650 lbs. to atmospheric pressurd taking place across the nozzle. Excellent results. have been secured in experiments ona piping-systern of moderate length with a minimum passage diameter of A, in combination with a discharge orifice of 5 diameter and therefore having 25% of the minimum area. of the passage leading to it.

In the present state of the art the viscosity and thermal properties of liquefied carbon dioxide are not known with suificient accuracy to form a basis for a general formula by which the size of the orifice and the minimum passage size may be determined.- It will be understood thatl the'above figures are the result'ofexperiment only and have been -found to give good results.v They are here a given for puyposes of illustration and the invention is, of. course, not limited to the sizes given.

The preferred relationship of pressure drop in the piping of lbs. or less with a pressure drop across the orifice of 650 lbs.

or more may be greatly modified and considerably more pressure drop permitted in the plping, if it is absolutely certain that i no moisture is present in the carbon dioxide. According to Faraday, carbon dioxide-- freezes to a solid at -56.50 G. and 5.3 at-' mospheres pressure (70 F.; at 78 lbs. per, square inch). It is evident that if the p1p;"; ing system is so designed that the'pressure can not at any point get below 78'lbs. per square inch until the carbon dioxide 'passes out thedischarge orifice, the carbon dloxido cannot possibly solidify in the piping and E stoppage of the piping willtherefore not oc cur. In practice, however, it is never cer- I tain that traces of moisture may 'not be" .-The actuaLsizeof the orifice in every casepresent, and it is therefore preferable to have a relatively small pressure drop along the conduit leading to the nozzle and to localize the greater. part 4 of the pressure drop at the nozzleorifice, since-a ve small amount of-water, iffrozen, may, 0 0g the piping or orifice. The preferred ressure drop and proportioning o'f-the ori ce area to the cross sectional piping area are calculated to 'prevenfi atemperature drop below the freezing point of water, and the dimensions stated have been shown by tests to result in no temperature below 32 F. behind the discharge nozzle when the storage container and assembly is initially at a tem perature of 50 F. or above. Commercial systems embodying my invention may be and are being operated successfully in which the orifice area is somewhat larger than 25% of the minimum .cross sectiona area-of the conduit leading from the container to the nozzle. f

The use of an orifice as above described in connection with a passage of materially larger diameter than the orifice gives rise to a localizing of the cooling effect at the nozzle. The tendency of the nozzle itself to freeze up depends largely upon the shape of the nozzle passage and orifice and the mate- 'rial of which the nozzle is made.

When'the' carbon dioxide is discharged into. the atmosphere from a nozzle having a constricteddischarge orifice, it expands tremendously as it emerges from the orifice. If an attempt be made to use the ordinary the orifice is substantially or reentrant, as shown for example in divergent stream of carbon dithe nozzle around i the orifice and chill it. The issuing stream as it expands beyond the'orifice consists of expanded gas together with carbon dioxide snow formed by the sudden expansion, and is very cold, being about -110 F. The nozzle surface around the fore subjected to intense cold and by conduction through themetal of the nozzle, the walls of the passage in the nozzle leading to the discharge orifice become chilled suflicharge passage.

cientlyto freeze the carbon'dio'xide snow or anoisture in 'thestre'am of carbon dioxide in the passage and cause 1t to become clogged.

If even a small amount of water is entrained in the carbon dioxide, it will greatly facilitate the freezing and clogging of the dis- I have found that such freezing in the discharge passage of the nozzle may be prevented by thermally insulat ing the discharge passage of the nozzle leading to the discharge orifice from the cooled issuing stream of carbon dioxide emerging indifferent ways, as for example, by making the nozzle of a thermally poor con-ducting material or so forming the nozzle that the expanding stream of carbon dioxide emerg- 'ing from the nozzle doesnot brush against 'the surface of the nozzle around'the orifice,

so thata heat insulating layer of air lies over the surface of the nozzle around the orifice.

orifice is therethe invention, reference numeral 1- indicates a storage container or tank shown as the usual carbon dioxide-containing cylinder and adapted to hold the charge of highly compressed carbon dioxide. The carbon dioxide will be in the form of a liquid, as indicated at 2, at ordinary room tempera-- turcs. The carbon dioxide is discharged through a conduit formed by a tube 3, ex-

tending to the bottom of the cylinder 2, and

a flexible hose 4 leading to the, discharge nozzle 5. A valve 6 is provided for releasing the carbon dioxide. A flaringhorn-fi is preferably fitted over the end of the nozzle to more effectively direct the issuing stream of carbon dioxide and prevent too great an entrainment of air. has a restricted discharge orifice 7.

over 25% of the cross sectional area of the passage 8 through the conduit leading to the nozzle. As shown in the drawings, the passage 8 terminates in a converging portion 9 tutes the periphery of the orifice 7. The

bores of the conduit leading from the carbon dioxide storage container or cylinder to the nozzle is of sufficient size so that the pressure drop 'along' such conduit 18 nowhere suflicient to permit expansion to a pressure low enough to form carbon dioxide snow; but in order to safeguard the conduit from clogging, in case water is present in the carbon dioxide, I prefer to-make the conduit of suflicient size so that there will be no pressure drop in itsufiicient to freeze water, and therefore, the carbon dioxide preferably will be delivered to the nozzle 5 at-a pressure approximating that of the initial pressure in the storage container. The stream of carbon dioxide delivered to the nozzle will, at temperatures below 88 F., consist of liquid carbon dioxide together with some gas produced by the bubbling of the stream as caused by the pressure drop along the conduit. Since the critical tem- The nozzle 5 The area of the orifice 7 is small, preferably not v restricted discharge orifice, it expands tre-' mendously .as it emerges from the nozzle orifice and with the ordinary type of nozzle having a fiat or reentrant face around the orifice, the-suddenly expanding divergent stream will brush againstthe surface 'of the nozzle around the orifice. A great expansion takes place just beyond the ori- 'fice wherethe carbon dioxide suddenly expands or flashes. into the gas 'at low pres-. sure, so that there is at this point a point of intense cold sufiicient to convert part of the expanded gas into snow. The envelope of the expanding stream beyond the orifice is' indicated approximately by the dotted lines 12in the drawing. The face of the envelope immediately. at the sides of the ori fice is at substantially right angles to the axis of the discharge passage through the orificeior may even be inclined slightly backward along such axis, so that if the face of the nozzle around the orifice is flat, the stream of expanding gas with its entrained v snow will brush against'the faceof the nozzle around he orifice.

Unless the walls of the passage leading to 'the orifice are insulated from the intense cold of the emergin stream of carbon dioxide, the walls in sucll passage will be chilled below the freezing "point of carbondioxide or'the freezing point of water and will collect either frozen Water or frozen carbon dioxide and the passage will clog. This insulation maybe accomplished by making the nozzle or portion ofthe nozzle adjacent to the orifice 7 of a thermally poor conducting material, such as bakelite. A nozzle of this g type is illustrated in Figure 2. Since the inaterial of the nozzle itself acts as aiheat insulator,.the face of the nozzle may be. flat, if desired, and the emerging stream may brush against-its outer face. i

-However, for mechanical reasons, an orifice of some corrosion-resisting and mechanically stron ,metal, such as Monel metal, is to be usuafiy preferred in practice. Since metal is a good heat conductor, other pro-, vision must be made in a'metal nozzle to insulate the passage leading to the orifice from the intense cold produced by .the

" emerging and expanding stream of carbon dioxide. This is preferably accomplished ease 'as shown in Figures 3 and 4, in which a metal nozzle is illustrated The face of the nozzle immediately'surrounding'the orifice 7 protrudes, as indicated at 13, so that the pointor region of the expansion or divergence ofthe issuing stream -of'carbon diox-C ide is projected beyond and out of contact with the face 10 of the nozzle.

in the drawings the portion 13 'ofthe nozzle protrudes sufliciently so thatthe oint of expansion of the stream of carbon ioxide emerging past the sharp .ed e' ofthe nozzle orifice issufi'iciently' 'beyon the face of the nozzle,'so as not to brush against it. As shown in the drawings, there is left a small layer of air between the envelope 12 of the expanding stream and the face 10 of the nozzle, which senvesas a heat insulator. The expanding stream will act somewhat as an aspirator to draw in this film of'air be- -tween its envelope and the face of the noz-. zle. I v In Figure 4 is illustrated a nozzle of the type shown in Figure ,3 as actually constructed. This consists of amozzle proper 5, which is threaded onto a'coupling mem-' ber 14, at the discharge end of the hose 4.

As shown ,The conduit passage 8 is continued into the nozzle and converges, as' indicated by referenceinumeral 9, to the restricted outlet orifice 7. The inner walls of the converging portion 9 of the no? protruding portion 0 'theouter face 10 of the nozzle to form 'the protruding sharp edge or lip 11 which defines the circumference' of the orifice. he outline of the discharged stream is'shown in dotted lines; in this figure. It will befseen that the ex: panded gas does not brush against the body of the nozzle in any ay and the ordinary tendency of a nozzle tofreeze is therefore eliminated. Preferred dimensions for thisnozzle are as follows: The diameter'of the conduit 6 is the diameter of the'nozzle .9 is and the portion .8 protrudes from the face of the nozzle body 4. It will be understood, of course, that these dimensions are for purposes of illustration fonly.

By thermally isolating or insulatlng the bore or passage of the nozzle within the orifice from the intense-cold of the emerging 1e passage meet the stream of carbon dioxidebeyond the orifice,

.I am enabled .to do away "with the application of heat 'to the nozzle, which has been one oftheremedies propo:ed to prevent noz-- zle freezing; The application of heat would necessitate the complications of a heating system and would be impractlcable, part-ic'ue larly with fire-extingulshmg apparatus,

'which should be available. for instantand I unfailing discharge.- It would be particularly impracticable to complicate a fire extinguisher' of the portable type with any auxiliary nozzle-heating device.

50 to form carbon dioxide snow in the conduit,

I I thus provide a highly effective means. by localizing f for'discharging carbon dioxide, the coolin effect at a point beyond the nozzle orifice and thermally isolatlng this point from the nozzle bore or passage leading to the orifice, thus eliminating the stoppages ordinarily met with due to solidification of the carbon dioxide itself or of the moisture contained therein. It will be understood, of course, that the invention is applicable to the discharge of carbon dioxide which is in gaseous form before it leaves the nozzle as :vvell as to gas which reaches the nozzle in liquid form. 15,

anally insulating the passage leading to the orifice from the cooled expanded stream of carbon dioxide einerglng from the orifice to prevent stoppage of flow therethrough.

2. The method of discharging carbon dioxide from a container holding the carbon dioxide under high pressure, comprising leading the carbon-dioxide from the contain-' er to a discharge nozzle through a conduit along which. the pressure drop is insufiicient ,to form carbon dioxide snow in the conduit,

dioxide into snow beyond and then passing the carbon-dioxide through a restricted nozzle orifice and thereby conthe issuing stream of carbon verting part of the nozzle orifice and thermally insulating the nozzle passage.

leading to the orifice from the cold developed by the expansion of the carbon dioxide beyond the nozzle.

- .3. The method of discharging carbon dioxide from a container holding the carbon 1 dioxide und'er highlpressure, comprising .leadlng Ier to a discharge nozzle through a conduit along which the pressure drop is insufiicie'nt and then passing the carbon dioxide through a ,restricted nozzle orifice and thereby con-.

vert'ing partof the issuing stream of. carbon dioxide into snow beyondthe nozzle orifice and preventln'g the expanding stream of carjbon dioxide'jgas and snow from brushing the reater surface of the nozzle. I

4. The method of. discharg ng carbon dioxide under pressure, comprising conducting the carbon d1 oxide,while retaining the reater part of this initial pressure, to a disc arge.

of discharging carbon, di-

thecarbon dioxide from the containv ing from the orifice:

and thermally insulating the passage leading to the orifice from the cold developed b the expansion of the carbon dioxide beyond the orifice.

5. T oxide under high pressure, ing the carbon dioxide through a discharge nozzle, and projecting the point of expansive he method of discharging carbon dicomprising passdivergence of the issulng stream of carbon.

dioxide beyond and out of contact with the nozzle.

6. Apparatus for discharging carbon dioxide under high pressure, comprising a container for holding compressed carbon dioxide,'a co'ndui-t leading from the bottom of the container, and a nozzle at the discharge end of the conduit having its outer face around thenozzle orifice tapered backwardly suflicient to prevent the expanding issuing stream of. carbon dloxide from brushing against the nozzle.

7. Apparatus for discharging carbon dioxide under hi h pressure, comprising a container for hol ing compressed carbon dioxide, a conduit leading from the bottom of the container, and a nozzle at the discharge end of the conduit having a nozzle passage convergingto a restricted discharge orifice, and having its outer face around the orifice tapered backwardly expanding issuing stream of carbon dioxide frombrushing'against the nozzle i 8. Apparatus for discharging carbon dioxide under high pressure, comprising a container for holding'compressed carbon diox-- .ide, a conduit leading from the bottom of the container, and a nozzle at the discharge end of the conduit having a converging nozzlepassage leading to a discharge orifice and having its outer face around the orifice tapered backwardly suflicient to prevent the expanding issuing stream of carbon dioxide from brushing against thenozzie, the surface. of the discharge-passage and the outer face of-the'iiozzle meeting at the circumference of the orifice edge; 5 y

9. Apparatus for discharging carbon dioxi eunder hi h pressure, comprising a container for hol ing compressed carbon dioxide, a conduit leading from the bottom of the container, and a nozzle at the discharge end of the conduit having a nozzle passage converging to a discharge orifice and having sufiicient to prevent the provision for thermally insulating the nozzle passage behind the orifice from'the cold expanding stream'of carb'ori' dioxide emerg In testimony whereof I have hereunto set my hand. l

p onxarns L. Jonas.

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