US2502588A - Portable apparatus for holding and vaporizing liquefied gases - Google Patents

Description

f April 4, 1950 l A l.. PRES-rau Erm. 2,502,588

Ponmu: APPARATUS Fon Homme ma VPORIZING LIQUEFIED GASES Filel April 11, 1945 '3 Sheets-Sheet 1 @will mvENToRs ALBERT L.PRESTON GEORGE H. ZE'NNER ATTORNEY April 4, 1950 A. L, PRESTON Erm. I 2,502,588

PORTABLE APPARATUS FOR HOLDING AND VAPORIZIHG LIQUEFIED GASES'l Filed Apr-11 11. 194s s sunk-sheet 2 lNvEN-r'ons ALBERT L. PRESTON GEORGE H. ZENNER INVENToRs ALBERT L. PRESTON GEORGE H. ZENNER ATTORNEY 3 Sheets-Skaai'. 3

A. l... PRESTON ET AL PORTABLE APPARATUS FOR HOLDING AND VAPORIZING LIQUEFIED GASES April 4,'1950 Filed Api-1111. 1945 Patented Apr. 4, 1950 PTEN'E @Eii'i PORTABLE APPARATUS FOR HOLDING AND VAPORIZING LIQUEFIED GASES Application April 11, 1945, Serial No. 587,656

l2 Claims.

l This invention relates to a portable apparatus for holding and vaporizing liqueed gasses and more particularly to apparatus for carrying liquid oxygen in aircraft and supplying gaseous oxygen under a desired pressure to a distributing system or consuming device.

Apparatus for storing and vaporlzing liquefied gases as customarily employed generally consists of a pressure-resistant vessel for holding a supply of the liquid, which vessel is protected by a surrounding layer of insulation retained within an outer shell. Various means have been employed to eect vaporization of portions of the stored liquid in order to produce gas under a desired pressure and in `the quantity required for use. One such vaporizing means comprises an electric immersion type of heater, the current supply to which is controlled by a rheostat. In the operation of such apparatus it is ideally desired that no evaporation of the liquefied gas should occur during periods of no demand for gas. In practice, however, even with best known type of heat insulation some leakage of heat from the surrounding atmosphere into the liquid occurs so that the liqueed gases cannot be stored for an indefinite period and provision must be made for such minimum rate of evaporation.

In a portable apparatus it is desired and often necessary that the apparatus be capable of movement into various positions and particularly in aircraft apparatus it is necessary that the device be operable to supply gas at the desired rate for an adequate period of time even in an inverted position. This requirment imposes unusual problems such as preventing an undue increase of heat leakage when in an inverted position, and of preventing the discharge of liquid through outlets which for normal operation should deliver only gas. Additionally, the apparatus should hold liquid for a required length of time, deliver gas in the quantity required, when required, and at a substantially constant predetermined pressure. It is also preferable that the apparatus should be light in weight, simple to operate and safe. Apparatus for the general type herein described which includes an insulated pressure vessel for holding a supply of liquefied gas and means for eiecting control of vaporization of portions ofthe liquid, is termed a cold converter.

It is, therefore, a principal object of the invention to provide an improved apparatus for holding and vaporizing liqueed gas, to deliver gas in quantities asvand when required at a predetermined pressure.

Further objects of the invention are: to provide such an apparatus which may be held in any position, including an inverted position, While the apparatus continues to hold the liquid without excessive vaporization or vaporizes the liquid and produces gas at a rate required for use; to provide a portable cold converter of the vacuum insulated necked construction, which has a gas chamber arranged in the neck communicating with the liquid-holding space in such a manner as Vto prevent excessive ow of liquid into the warm end of the neck when the cold converter is in the inverted position; to provide a cold converter having liquid phase and gas phase connections arranged with trapping means to prevent substantially increased vaporization of liquid when the cold converter is tilted or inverted; and to provide a cold converter of the necked construction in which the heat leak through the neck is low.

These and other objects of the invention will in part be obvious and in part become apparent from consideration of the following description in connection with the accompanying drawings in which:

Fig. i is a View mainly in vertical cross-section of an exemplary cold converter construction embodying the invention.

Fig. 2 isa plan -view of the cold converter shown in Fig. 1.

Fig. 3 is a sectional view of a cold converter illustrating particularly an alternate form of gas phase trap and;

Figs. 4, 5, and 6 are fragmentary sectional views i illustrating still other arrangements of the gas phase trap.

Referring to the drawings and more particularly to Fig. 1, the cold converter includes an inner vessel It, which may have any suitable shape, the spherical shape as illustrated being generally preferable. strong enough to withstand safely a predetermined working pressure, which working pressure is the pressure under which gas is delivered from the converter. The cold converter is preferably provided with a vertically extending neck li, secured at its upper end to a head block l2. A

. gas discharge conduit i3 is connected to the head block i2 to communicate with the interior of the neck il. The upper end ofthe neck il is closed by a removable'plate Ii, which is secured gas tightly against the upper face'of the head :block l2. From the plate ill, there extends a tube l5, downwardly through the neck li into the liquid holding space of the vessel it. The tube l carries at its lower end an electric immersion type The vessel i@ is made oi heater I5. The electric wires for supplying energy to the heater extend through the tube I5 and pass through an insulating bushing Il in the plate I4. From the bushing II, the wires I8 pass through an electric conduit I9 which is secured to the top of the plate I4.

The space between the wall of the neckII and the tube I5, forms a gas chamber 20 which is closed at its upper end by the plate I4, and at its lower end by an annular member 2|. The lower end of the neck II extends within the `vessel I a short distance and is provided with an internal shoulder 22 against which the annular member 2| forms a seal. The annular member 2| extends around the tube I5, and is slidable thereon so that it can be urged against the shoulder 22 by a spring metal bellows 23, which. surrounds the tube I and is gas tightly secured at its lower end to the annular member 2|, and at its upper end to the tube I5. Thus when it is desired to remove the heater I6 and tube i5, it is merely necessary to loosen 'the plate I4 and withdraw the assembly. When the heater assembly is inserted and the plate I4 secured in place, the bellows 23 will be compressed so that it urges the annular member 2| against the shoulder 22, and a sealed chamber 2i) is thus obtained.

Gas phase communication between the vessel i0 and the gas chamber 20 is maintained through a trapped conduit 213. The conduit 24 has an inlet opening 25 at a point near the top of the gas space in the vessel IB, and is formed to have a convolution 26 substantially in the horizontal plane. The conduit 24 also has a convolution or loop 2l substantially in a vertical plane, and the remaining end 28 is secured to the portion of the neck I I that extends within the vessel I0 so as to open into the chamber 2|). The chamber 20 thus is provided with 'a universally trapped connection with the gas space of the vessel Ill.

The vessel I0 is enclosed within a suitable heat insulating means which may be one of several vessel the vacuum type of insulation may be preferable. To this end there is provided an insulating jacket or shell 3|! which is spaced from the outer wall of the vessel I0 to provide an insulating space 3|. The space 3i is evacuated to a high degree and both the outer surface of the vessel I0 and the inner surface of the jacket 3|'i are highly polished to reduce heat radiation. Jacket 36 also has an extension 32 around the neck II, and the upper end of such extension is secured to the head block I2 in a gas tight manner, such as by welding.

The entire container is supported by a suitable frame such as a surrounding cylindrical shell 33 having an upper conical portion 34 which is sccured to the head block I2. It will be seen, therefore. that the inner vessel is suspended by its neck II from the head block I2, that the outer jacket 3|) is independently suspended from the head block I2, and the head block I2 is carriedv by the conical portion 34 on the shell 33. The lower edge of the shell 33 is provided with a rim or ange 35 which may be employed to secure the converter to the door of a vehicle or to a portion of an airplane.

The converter is also provided with means for lling the vessel with liquid and discharging liquid therefrom. Such means may be in the form of a conduitl 36 which extends into the vessel I0 and passes through the insulation space 3| to the head I2, to which it is secured in a manner to communicate with a passage 31 therein into which a pipe 38 is secured. A stop valve 39 preferably connects the pipe 38 with a filling connection 40. The liquid phase conduit 36 is also universally trapped by having therein a loop 4I in a vertical plane preferably disposed within the vessel III, and a plurality of loops or convolutions 42 substantially in a horizontal plane, the loops 42 being preferably disposed in the vacuum space between the neck |I and the extension 32, and encircling neck II. The convolutions 42 not only provide a trap substantially in the horizontal plane, but also serve to increase the length of the conduit 36 between the point where it leaves the vessel I0 and the head I2 which latter is warm. Such increased length substantially reduces the conduction of heat through the metal walls of the conduit 36.

Means for measuring the quantity of liquid in the vessel I 0 are usually also provided. Such i customary types of insulation. For a light weight l means may be oi two types. for example, the trycock and the liquid level gauge types. For the liquid level indicating trycock, a small tube 43 is provided having an inner end 43' located` within the 'vessel Il) at a desired level. The tube 43 is elso universally trapped by having a loop 44 in the vertical plane and eonvolutions 45 in the horizontal plane disposed about the neck I I. The

tube 43 passes through the insulating jacket preferably at the head I2 and ls connected to a trycock 46 (Fig. 2). Connections for a customarv type of liquid level gauge 41 are similarly provided. The low pressure side of such liquid level gauge 41 may be connected to the leras chamber 2n hv a connection 41 similarly to conduit I3. The high pressure connection .for the liduifl level gauge is provided by a tube 48, which passes through the insulating jacket to a point near the bottom of the vessel I0 wherein it is secured gas tightly with its open end in communication with the Iinterior of a. small cap 50. The'cao 5|! has its rim secured to the interior wall of the vessel In and is provided with one or more openings 5| aiacent to the wall oi the vessel I0.

In operation, a charge of lioueiied gas is forced in at the connection 4|) while the valve 39 is open. The trvcor-k 46 at the end of the tube 43 is also onen and the gas conduit I3 preferably would be open to the atmosphere through a valve I3' therein, although if it is desired to save the oxygen vapors, the Valve I3' may be connected to a low pressure gas receiver. As the liquid level rises in the vessel IIJ. thatlevel at which the end 43' of the tube 43 is positioned will be reached and such occurrence will be indicated by a blow of liquid from the trycock 46. At this time the valve 33 is closed and the valve I3 for venting the gas conduit I3 as well as the trycock 46 are also closed.

If it is desired to put the converter into immediate use for supplying gas, the electric heater will be connected at a socket I9' on the conduit I9 to a source of electric current. The heater causes sufdcient vaporization to bring the pressure up to working pressure, after which a pressure control 52 connected to conduit I3, operates to regulate the current supply so that the rate of heating and vaporization correspond to the rate at which gas is withdrawn through the gas conduit I3. The working pressure usually is that which it is desired to maintain in the gas distributing or using apparatus, for example, the oxygen distributing manifold of an airplane which may operate at a standard pressure of 400 p. s. i. or a lower pressure such as 65 p. s. i. If gas under pressure is not required immediately after filling the converter with liquid, the socket I9 is left disconnected and Vthe converter may be allowed to stand with all valves closed for a considerable period of time before normal heat leak from the atmosphere to the vessel I6 is suiiicient to heat the liquid and vaporize enough of the liquid to bring the pressure up to the, working pressure. If, after the pressure has reached working pressure, no gas is consumed, continued heat leak from the surroundings will cause evaporation to occur at a low rate and tend to further increase the pressure. Therefore, in order to avoid the occurrence of an excessive pressure, a safety relief valve 53 (Fig. 2) is customarily provided and such valve is preferably arranged to communicate with the gas chamber 26 through a connection 53'.

If the converter is positioned up-side-down, the vertical loop di in the conduit 36 forms a trap that prevents flow of' liquid through the conduit 36 toward the head l2, particularly since the conduit 36 is dead-ended by the valve 39. For example, some liquid will ordinarily stand in the lower part of the tube 36, and when the converter is inverted a small portion of such liquid may flow past the loop 3l and enter the warmer portions of the coils 42 wherein it vaporizes. A dead ended pocket of gas however results in the portions of conduit 36 between the trap loop di and the valve 39 which prevents further flow of liquid over the high point of the trap 4l and a liquid level will w stand in the trap. The loop it in the tube 53 operates in a similar manner.

The normal gas phase trapv inlet 25, will be submerged in liquid when the concerter is up-sidedown but such liquid will be prevented from rising through the tube 24 by gas pressure in the gas chamber 26 and tube 25 due to the loop portion 2l in the vertical plane. If, however, gas is withdrawn through the gas conduit i3, liquid will rise in the loop portion 21 until some of it ows over the bend. Such liquid that flows over the bend will fall through the gas chamber 26, and eventually come in contact with the head l2. The head i2 is relatively very hot being substantially at atmospheric temperature so that any liquid that reaches it will be immediately vaporized.` Such vaporization restores the pressure in the chamber 20, which pressure serves to prevent excessive liquid from owing over the bend of the loop 2l. It will be seen then that only that Pamount of liquid which is needed to produce the gas that is withdrawn through conduit i 3 will flow into the gas chamber 26.

Operation in the up-side-down position will occur for an appreciable and desired length of time because the head l2 is relatively massive and the -metal from which it is constructed contains an appreciable store of heat. Furthermore, heat is continually absorbed by the head i2 from the atmosphere. The head i2 thus functions as a heat lreservoir for operation of the converter when in the up-side-down position.

When the converter is placed in a position lying on its side, for example, the traps or trap loops' yt2, t5 and 26 become operative to prevent ow of liquid through the conduits 36, t3 and the trapped conduit 2d, because such trapping convolutions are now in the vertical plane. If the trap inlet 25 is below liquid level when the converter is on its side, a supply of gas at the desired pressure may be still obtained through the conduit I3, because the trap and gas chamber 20 will function substantially as described in the up-side-down posif ton. If, however, the inlet 25 is in the gas space above the liquid level, the converter will function to produce gas in the normal m'anner as -described when it is vertical.

The gas phase chamber and trap assembly may have various forms as illustrated, for example, in Figs. 3 to 6. Referring to Fig. 3 particularly, the inner vessel H0 is surrounded by an insulating space I3I, which may Ibe filled with a comminuted or powder insulating material held within an outer jacket |36. The vessel H0 has a neck lll, which extends to the upper end of the jacket |30 and is suspended therefrom. In this embodiment a unitary gas chamber and heaterv insert assembly is provided. The insert assembly'comprises a tube 54, having upper and lower heads and 56. The upper head 55 is provided with a flange 51 that is secured gas tightly to a corresponding flange 58 at the upper end o f the-neck lll. The lower end of the tube 54 enters the vessel lll) a short distance and is placed in gas phase communication with the interior of the vessel H6 by a trapped connection lZt-'disposed entirely within the gas chamber i2@ in the tube 5G. The lower end of the connection 25 passes through the wall of the tube 5t and opens into the vessel H0. The connection i213 is provided with one or more loops or convolutions |26 in the horizontal plane and a loop or convolution l2? in the vertical plane, thus providing trapping in any position. The heater tube H5 passes gas tightly through the heads 55 and 56 to which it is secured. The gas discharge conduit H3 preferably passes through the head 55 and extends within the gas chamber in the tube 55 a short distance, which has the advantage that liquid cannot blow out through the conduit H3 during operation in the up-sidedown position.

In Fig. 4 the gas phase trap 22d is also disposed within the gas chamber 220 but the arrange ment dilers from that of Fig. 3 by having they trap tube 22d risev vertically to a loop 22'3 disposed in the vertical plane and then be formed with a loop or convolutions 235 disposed in the horizontal plane below the loop 227.

In Fig. 5 a gas chamber 320 within the converter neck 3H is yformed by a partition 59 near the joint between vthe neck 3H and the vessel 3l6. The trap connection 32d is provided with an inlet 325 near the top of the vessel 3H) with horizontal loops 326 and with a vertical plane loop 321 below the loops 326. The outlet end of the connection 525 passes through and is secured to the partition 59.

In the embodiment shown in Fig. 6, the inner vessel M6 has a vertical extending neck 4| l, and a combined heater and gas chamber assembly 60 is employed. The assembly 66 comprises a relatively long tube .6l that extends through the neck iii to a point near the bottom of the vessel dit. The tube 6i is closed at the bottom and a .heater element is preferably disposed therein near the bottom. At a point near the top of the vessel dit the tube 6l is provided with a vtransverse partition v62 to which is secured a heater conduit 53, through which the electric wires for the heater may pass. Just above the partition 62 are openings 6ft in the wall of the tu'be 6i. To form apart of the desired gas chamber, a cup-shaped sealing member 55 is provided which is welded gas tightly to the upper part of the vessel till, and has a bottom 66 having a central hole 6l through which the tube 5l passes. The bottom 56 is just below the openings Sli. The hole 67 fits the tube sufficiently closely to provide a sliding fit so that no appreciable arcanes space when the converter is in the up-side-dowxi4 position. The gas chamber is thus formed by the space within themember 85, the space between the tube 6I and the heater conduit 83 and the space between the tube 8l and the wall oi the neck 4H. The gas phase connection between such gas chamber and the vessel 4I0 is provided by the connection 424 which has an inlet 425 near the upper part of the vessel 4i0 outside oi the member 65 and which is provided with horizontal `loops or convolutions 426 and a vertical loop 421. The remaining end oi the connection 424 enters gas tightly through member 8B to communicate with the gas chamber.

The operation of the alternative forms of gas chamber and trapped gas phase connections as shown in Figs. 3 to 6 inclusive, is substantially the same as described in Figs. 1 and 2. An important path for heat leakage to the liquid holding vessel is through the metal of the neck. Although lengthening the neck reduces such heat leak, it is usually essential to make the neck as short as possible in order that the converter shall be no higher than space requirements in an airplane permit. At the same time the converter must have a required liquid holding capacity. For these reasons4 itwill generally be preferable to have a minimum of metallic paths tor heat conduction down the neck, thus when the neck is to be short, it is more advantageous tc employ a construction in which the gas chamber within the neck is `formed by the neck walls as in Fig. 1 and is not within an inserted assembly as in Figs. 3 and 6. The inserted assembly construction however has the advantage of making it unnecessary to provide a liquid iiiling connection because the converter can be iilled with liquid through the neck fwhile the insert assembly is removed and when it is desired to put the converter into operation the heater assembly may be inserted and secured in place.

Although several embodiments of the inven tion are disclosed in detail, it is contemplated that numerous changes may be madeA in such details without departing from the principles ci the invention, for example, although an electric heating means has been shown, a heating means of the type employing a heated uid may be substituted or a heating means external ot the inner vessel may be employed and, although the converter has been described particularly for the conversion of liquid oxygen to provide gaseous oxygen, it is to be understood' that simi-lar apparatus canv be employed for gasifying other liquefied gases.

What is claimed is:

1. A gas dispensing apparatus comprising an inner vessel for holding a body of liquefied gas; a heat insulating jacket surrounding said vessel having an outer shell; and conduit means extending from within said inner vessel through said heat insulating jacket to a point externally `of said outer shell, said conduit means having a plurality of complete convolutions, at least two of which lie respectively in planes which are substantially perpendicular to each other and define a continuous passageway, said convolutions being disposed internally of said outer shell to prevent gravitational ow of liquid through said conduit means in any and all positions of the apparatus.

2. An invertible gas dispensing apparatus comprising an inner vessel for holding a body of liqueed gas, a heat insulating jacket surrounding said Avessel having an outer shell; and a gas phase passage means for conducting gas material from a point normally near the top oi' said inner vessel to a point externally of said outer shell, said passage means comprising a gas chamber having a warm end spaced from said inner vessel, a cold end adjacent said inner vessel, at least the major part of said gas chamber including its cold end being within said insulating jacket, a gas discharge connection at said warm end, and a restricted connecting means providing communication between said cold en d portion of the gas chamber and the normally gas phase space oi said inner vessel.

connection providing communication between the inner end portion of said gas chamber and the normally gas phase space of said inner vessel.

4. A gas dispensing apparatus according to claim 3 in which said trapped connection comprises a tube having portions disposed substantially in planes which are perpendicular to each other.

5. A gas dispensing apparatus according to claim 3, in which said trapped connection is disposed entirely within said inner vessel.

6. A gas dispensing apparatus according to claim 3 in which said trapped connection is disposed entirely within said gas chamber.

7 A ges dispensing apparatus according to claim 3 in which said inner vessel is provided with an extending neck portion, said gas chamber is disposed with said neck portion the major part oi which is within said insulating jacket, and the warm end of said gas chamber is in heat exchange relation with a heat reservoir at the outer end of said neck portion.

8. In a portable cold converter of the type having an inner vessel for holding liquefied gas surrounded by a heat insulating jacket; a liquid conduit means; a gas phase conduit means; and

a liquid level indicating conduit means; each oiv said conduit means having an open end within said inner vessel and passing through said insulating jacket to an external point; and traps in each of said conduits arranged to prevent gravitational ow of liquid through said conduits in t the up-side-down position.

9. In a portable and invertible cold converter of the type having an inner vessel for holding liquened gas surrounded by a heat insulating ljacket; a neck extending outwardly from said inner vessel, said neck being secured to a head at its outer end; a gas chamber in said neck having an outer end closure connectable to said head and an inner end closure, at least the major part of said gas chamber being protected from atmospheric heat by said insulating jacket; a heater element having a heatable portion within the liquid space of said inner vessel, and a conduit portion extending through said gas chamber and said end closures; a gas discharge connection at the outer end of said gas chamber; and means providing restricted gas phase communication between said gas chamber and the normally gas containing space of said irmer vessel.

10. Ina portable and invertible cold converter of the type having an inner vessel for holding liquefied gas surrounded by a heat insulating jacket; a neck extending outwardly from said inner vessel, said neck being secured to a head at its outer end and the remainder of said neck being disposed within the insulating jacket, said neck also having an internal shoulder adjacent its inner end; a removable heater element having a heatable lower portion within said inner vessel, a conduit portion extending through saidneck and means at its upper end for securing said element to said head; a yieldable sealing means carried I by the conduit portion of said element in sealing engagement with said shoulder in the neck for forming a gas chamber within said neck, means providing gas phase connection between said gas chamber and the inner vessel; and a gas discharge connection at the outer end ofv said neck for discharging gas fromsaid gas chamber.

11. In a portable and invertible cold converter of the type having an inner vessel for holding liqueed gas surrounded by a heat insulating jacket;

tudinally through said gas chamber and gas tightly through said end closures and a heater portion disposed within the liquid holding space of said inner vessel, and a liquid trapping connection providing gas phase communication between the lower portion of said gas chamber and the gas phase space of said inner vessel.

12. In a portable and invertible cold converter of the type having an inner vessel for holding 4 liquefied gas surrounded by a heat insulating jacket; a tubular neck extending outwandly from said inner vessel, said neck having a head at its outer end and the remainder of said neck being disposed within the insulating jacket; and an insert assembly through said neck, said insert as sembly comprising a tube having at its upper end an end closure and means for securing it gas tightly to said head and a transverse partition or closure adjacent the joint between said neck and the inner vessel, a heater element conduit in said tube and passing gas tightly through said upperl end closure and said partition, a heater portion below said partition extending within the liquid holding space of said inner vessel, a cup member lwithin said inner vessel having a rim secured gas tightly to the upper inner wall of said inner vessel and having a bottom with an opening through which said tube passes, said cup member forming an annular chamber about said tubeV having a close sliding fit in said opening to prevent excessive liquid flow therethrough, an opening in the wall of said tube providing communication between said annular chamber and the interior of said tube above said partition and a liquid trapping connection providing gas phase communication between said annular chamber and the gas space of saidinner vessel.

ALBERT L. PRESTON. GEORGE H. ZENNER.

REFERENCES CITED The following references are of record in the ille of this patent:

UNITED STATES PATENTS Number Name Date 1,522,886 Heylandt Jan. 13, 1935 1,998,629 Lagarde Apr. 23, 1935 2,166,574 Adolphsen July 18, 1939 2,385,984 Hansen et al Oct. 2, 1945 2,401,651 Mathis et al. June 4, 1946 FOREIGN PATENTS Number Country Date 420,685 Germany Oct. 30, 1925 426,472 Germany Mar. 11, 1936 Certificate of Correction Patent No. 2,502,588 April 4, 1950 ALBERT L. PRESTON ET AL.

It is hereby certified that errors appear in the printed speeication of the above numbered potent requiring correction as follows:

Column l, line 45, for the Word for after Apparatus read of; column 8, line 42, for With read within;

and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Oce.

Signed and sealed this 1st day of August, A. D. 1950.

[SEAL] THOMAS F. MURPHY,

Assistant Uommz'sszoner of Patents.

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