US3260061A

US3260061A - Flow system for cryogenic materials

Info

Publication number: US3260061A
Authority: US
Inventors: Robert S Hampton; Owen S Jones; Josephian William
Original assignee: Lox Equipment Co
Current assignee: Lox Equipment Co
Priority date: 1964-12-16
Filing date: 1964-12-16
Publication date: 1966-07-12
Anticipated expiration: 1983-07-12

Description

July 12, 1966 Filed Dec. 16, 1964 R. s. HAMPTON ETAL 3,260,061

FLOW SYSTEM FOR CRYOGENIC MATERIALS 2 Sheets-Sheet l M L.I I I I LJ I LI E z 7 Z INVENTOR. ROBERT 5. HAMPTON OWEN SJONES BY W/L LIAM JOSEPH/AN g 2 iZTTORNEYS July 1966 R. s. HAMPTON ETAL 3,260,061

FLOW SYSTEM FOR CRYOGENIC MATERIALS Filed Dec. 16, 1964 2 Sheets-Sheet 2 INVENTOR. 46 an 65 ROBERT 5 HAMPTON BY OWEN ado/v55 a9 WILL/AM JOSEPH/AN United States Patent 3,260,061 FLOW SYSTEM FOR CRYOGENIC MATERIALS Robert S. Hampton, Livermore, Owen S. Jones, Oriuda, and William Josephian, Oakland, Calif., assignors to Lox Equipment Company, Liver-more, Calif., a corporation of California Filed Dec. 16, 1964, Ser. No. 418,759 8 Claims. (CI. 62-52) This invention relates to a flow system of a type arranged to pump cryogenic materials, such as liquid oxygen, liquid nitrogen, liquid argon, etc., from a large capacity storage vessel and to convert the liquid to a gaseous state for delivery to a plurality of transportable gas cylinders, or the like. The invention is more particularly directed to a system of this type in which access may be had to valves for controlling the flow of cryogenic material from the vacuum jacket insulated storage vessel of the system Without the simultaneous establishment of excessive heat leaks to the system.

In the effic-ient filling of the transportable cylinders or containers with oxygen, nitrogen, and other gases at ambient temperature and high pressure, it is the usual practice to pump the material in liquefied form from a large capacity storage vessel to a heat exchanger wherein the liquefied material is vaporized for delivery to the cylinders. The liquefied material is at cryogenic temperatures which must be maintained in order to prevent the material from vaporizing or reverting to the gaseousstate. From the standpoint of efiiciency, it is desirable that the material be maintained in liquid form in the portions of the flow system preceding the discharge side of the pump provided to deliver the material from the storage vessel to the heat exchanger. Accordingly, precautions must be taken to minimize heat leaks into such portions of the system. To this end, the storage vessel is conventionally provided with a vacuum jacket which contains insulating material in addition to being evacuated to low pressure so as to very effectively insulate the vessel interior from the ambient surroundings. Typically, supply and equalizer lines extend from the vessel through the jacket to the pump, and means are provided to insulate the pumping head of the pump. However, valves are provided in the supply and equalizer lines for controlling the fiow of material through the system and in order that these valves be accessible they are commonly disposed exteriorly of the vacuum jacket of the vessel and of the head insulating detracting from the pumping efficiency thereof. Alternatively, the valves may be located Within an extension of the jacketed vacuum void of the storage vessel. However, as so located the valves are not accessible for necessary repairs or replacement and the like without opening the vacuum void to the ambient surroundings and thereby breaking the vacuum. As a result, the insulating properties of the jacket would be seriously deterimented and opening of the jacket could not be accomplished except under conditions of complete shut down of the system, and such repairs are very expensive in labor and lost operating time.

Accordingly, it is an object of the present invention to provide a cryogenic flow system of the type outlined above which is so arranged that the valve means between the vacuum jacketed storage vessel and the pump are very effectively thermally insulated and yet are readily accessible without requirement of opening the vacuum jacket.

Another object of the invention is the provision of a system of the class noted hereinbefore which features a sump having a vacuum jacket thereabout in communica- 3,260,061 Patented July 12, 1966 tion with the vacuum jacket of the vessel, the sump being communicated with the vessel through valve means located in the sump interior and being adapted to contain cryogenic material and to support the pump therein in a position wherein the head of the pump is immersed in the cryogenic material.

It is still another object of the invention to provide a system of the character described wherein the valve means in the sump interior are accessible through a pump receiving opening into the sump upon removal of the pump therefrom.

It is a further object of the invention to provide a cryogenic material flow system of the class described which may be shut down for periods of the order of several days without requirement of closure of the valve means between the vessel and pump, thus having the unit ready on instant notice to initiate cylinder filling, yet maintaining very low heat leak between runs.

A still further object of the invention is the provision of a cryogenic material flow system which requires a minimum of manipulation in the filling of containers with gas.

The invention possesses other objects and features of advantage, some of which, with the foregoing, will be set forth in the following description of the preferred form of the invention which is illustrated in the drawings accompanying and forming part of the specification. It is to be understood, however, that variations in the showing madeby the said drawings and description may be adopted within the scope of the invention as set forth in the claims. I

FIGURE 1 is a schematic flow diagram of a system in accordance with the present invention for pumping liquefied gas from a large capacity storage vessel and converting the liquid to the gaseous state for delivery at ambient temperature and elevated pressure to gas cylinders or the like.

FIGURE 2 is a fragmentary sectional view of a portion of the storage vessel as associated with a novel pumping sump and valve arrangement of the system.

FIGURE 3 is a plan view of the sump as taken at line 33 of FIGURE 2, a pump of the system being removed.

FIGURE 4 is a schematic illustration of a modified form of sump and valve arrrangement which may be employed in the system.

Referring now to FIGURE 1, there is shown a flow system for pumping cryogenic material such" as liquid oxygen, liquid nitrogen, liquid argon, or other'liquefied gas from a large capacity storage vessel 11, through a heat exchanger 12 wherein the liquid is vaporized, to an outlet 13 wherefrom the gaseous material is delivered at ambient temperature and elevated pressure to a manifold or the like (not shown) for filling a plurality of transportable gas storage cylinders or containers of the type commonly employed in hospitals, laboratories, etc. The storage vessel 11 includes an inner container 14 for storing the liquefied gas, which is necessarily maintained at cryogenic temperaures to prevent its reversion to the gaseous state, and an outer jacket 16 spaced from the inner container to define a void therebetween. The void is typically filled with insulating material, and a vacuum valve 17 is communicated with the void to facilitate evacnation thereof to vacuum dimensions by means of a suitable vacuum pump. The insulating material and vacuum provided about the inner container 14 thus comprise a vacuum jacket which very effectively thermally insulates the inner container from the ambient surroundings whereby theliquefied gas may be stored in the container for substantial periods with little reversion to the gaseous state.

To facilitate filling of the vessel 11 with liquefied gas,

inlet and

vent lines

18 and 19 are communicated with the interior of container 14 at respectively its lower and upper ends. In a typical arrangement, a fill valve 21 connects line 18 to a fitting 22 adapted for connection to a source of liquefied gas, while line 19 is externally terminated in a vent valve 23. In addition, a cross-over valve 24 is connected between line 19 and the fitting 22. Thus, to initially fill the vessel, the fitting 22 is connected to a liquefied gas source and

valves

21 and 23 are opened, while valve 24 is retained closed, to thereby fill the container 14 from the bottom. When the container is nearly full,

valves

21 and 23 are closed. After the vessel has been in service and requires refilling, it may be desirable to fill the container 14 from the top, in which case the

valves

21 and 23 are maintained closed while valve 24 is opened. This allows filling to a controlled vessel pressure as bottom fill tends to increase the pressure while top fill lowers the pressure by gas absorption by the colder liquid as delivered under normal conditions.

Pumping of the liquefied gas from the vessel through the heat exchanger 12 is accomplished by means of a pump 26 driven by a motor 27. In this regard, a sump 28 is advantageously provided and communicated with the bottom and top of container 14 by means of flow and

equalizer lines

29 and 31 which extend through the vacuum void of the vessel. Sump supply and

return valves

32 and 33 are included in the

lines

29 and 31 to facilitate control over the flow of liquefied gas between the vessel and sump. With these valves open, liquefied gas partially fills the sump as indicated at 34. The pump is disposed in the sump with its pumping head 36 immersed in the liquefied gas 34 therein.

The outlet of the pump is connected through a line 37 to the inlet of the heat exchanger 12, the outlet of which is connected through a valve 38 to the gas outlet 13. The liquefied gas is vaporized in passing through the heat exchanger by warm water circulated through the heat exchanger and a water heater 39 by means of a pump 41. Heat may be added by other means, as for example from the atmosphere in an ambient vaporizer.

To complete the basic flow system, a pressure gauge 42 and pressure switch 43 are connected to line 37 adjacent the inlet to the heat exchanger. The pressure switch is coupled in controlling relation to the pump motor 27, as indicated by the wavy line 44, so as to start and stop the same in accordance with a preset shut-off pressure indicated by the pressure gauge 42. More particularly, the

pump 26 may be started by means of start switch provided as an integral component of the motor 27. The liquefied gas is thereby pumped through the heat exchanger 12 and is vaporized therein such that gas is delivered from outlet 13 to the manifold for filling the transportable gas oontainers. As pumping continues, pressure builds up in the containers as well as in the portions of the flow system preceding the outlet 13. When the preset shut-ofi pressure is attained in the containers, the pressure switch 43 operates to responsively deenergize the motor 27, thereby shutting down the pump. When the filling manifold is subsequently communicated with a new line of containers, the pressure in the system of course drops, and the pump may be restarted by touching the start button.

The function of the

valves

32, 33, as noted previously is to control the flow of liquefied gas between the storage vessel 11 and sump 28. For extended shut-down of the system the liquefied gas in the sump, as well as any vapor overlying the liquid, are desirably returned to the storage vessel. This is accomplished by closing the valve 32 while leaving the valve 33 open. As a result, most of the liquid in the sump is forced back into the vessel through valve 33. Valve 33 is then closed and valve 32 opened. Any small remaining amount of liquid in the sump then eventually vaporizes and the gas flows through valve 32 into the top of the vessel container 14 to build up the pressure therein. Part of this gas is then absorbed in the liquid in the container. Valve 32 may then be closed. To resume operations,

valves

32, 33 are opened to deliver liquefied gas to the sump for pumping.

It will be appreciated that the system described above is in basic respects conventional and that numerous relief valves, regulators, and other additional auxiliary components not shown in the drawings are typically included in the system. However, as noted previously problems have arisen in conventional systems of this type with respect to the valve means for controlling flow of liquefied gas between the storage vessel and pump, i.e., the

valves

32, 33 in the present case. Normally, these valves are included in the system at positions exteriorly of the vessel, between the vessel and pump of pumping sump, so as to be accessible for purposes of maintenance or the like. However, as so positioned, the valves constitute heat leaks to the system tending to undesirably vaporize the liquefied gas. In alternative previous arrangements, the valves are disposed in the vacuum jacket void of the storage vessel. The valves are thus thermally insulated, but inaccessible for maintenance purposes without opening the void and destroying the vacuum therein.

The present invention overcomes the problems associated with system for pumping cryogenic materials by providing an arrangement wherein the valve means between the storage vessel and pump are thermally insulated and yet are readily accessible for maintenance or the like. In accordance with the basic aspects of the present invention, the pumping sump 28 is provided with a vacuum jacket and the vacuum void encompassing the sump is communicated with the vacuum void of the storage vessel. The flow lines between the vessel and sump extend through the vacuum voids thereof into the sump interior and are thereat terminated in the valve means. Moreover, the arrangement is such that upon removal of the pump from the sump an access opening is provided to the interior of the sump, thereby rendering the valve means accessible.

Considering now the arrangement of the present invention in greater detail as to the preferred structure thereof, and referring to FIGURES 2 and 3, it is to be noted that the sump 28 includes an inner container 46 which is preferably cylindrical and is closed at its upper and lower ends by

closure walls

47, 48. In addition, container 46 is provided with an outwardly flared annular flange 49 at its upper end. Such flange forms the upper end closure wall of a cylindrical jacket 51 closed at its lower end. The container is thus supported by the flange in inwardly spaced concentric relation to the jacket and in longitudinally spaced relation thereto at its lower end. A void 52 thus encompasses the inner container 46 of the sump.

The sump 28, as thus provided is preferably disposed within a space at the lower end of the storage vessel 11 encompassed by a support skirt 53 thereof. The void 52 of the sump is then communicated with the vacuum void of the vessel as by means of an elbow conduit 54 sealably secured at one end within an opening through the bottom wall of the vessel jacket 14 and at the other end within an opening in the peripheral wall of the sump jacket 51. A vacuum is thus established in the sump void and thermal insulating material may be advantageously disposed therein to enhance the insulating properties of the vacuum jacket. The supply and

equalizer lines

29, 31 extend through the vacuum void of the vessel, the conduit 54, the sump void 52, and through the peripheral wall of the container 46 in sealed relation thereto, into the interior of the container. The

vales

32, 33 are connected to the ends of

lines

29, 31, and are consequently disposed within the interior of container 46. The equalizer valve 33 is positioned at a point of the container above the normal level of liquified gas 34 contained therein, while a pipe 56 extends from the outlet port of supply valve 32 to a position adjacent the lower end of the container. The

valves

32, 33 are both preferably gate valves provided with elongated control stems 57, 58 extending upwardly through

sleeves

59, 61 mounted in the upper end wall 47 of the container,

Discs

62, 63 are preferably secured to the external ends of the stems 57, 58 to facilitate the ready rotation thereof in valve opening and closing directions.

To facilitate operative positioning of the pump 26 within the interior of the inner container 46 of the sump, an opening 64 is provided in the end wall 47. The pump fits through the opening 64 and is provided with a flange 66 at an intermediate position thereof adapted to engage the upper face of end wall 47 about the opening 64 and support the pump in a position wherein the pumping head 36 thereof is beneath the normal level of liquefied gas in the container. The pump flange is removably secured to the top wall of the container as by means of flange bolts 67. Thus, upon removing the flange bolts, the pump may be withdrawn from the container through the opening 64. With the pump thus removed, as depicted in FIG. 3, the opening 64 affords access to the

valves

32, 33 in the interior of the sump container. Inasmuch as the inner container is vacuum jacketed, the valves disposed therein are very effectively insulated from the ambient surroundings to thereby greatly minimize vaporization of the liquefied gas due to heat leaks. By virtue of the insulation of the values they may be left open during periods of shut down of the order of several days. Moreover, access to the valves does not entail opening of the vessel vacuum void to atmosphere.

Referring now to FIG. 4, a modified form of the invention is schematically depicted which in basic respects is similar to the embodiment of FIGS. 2 and 3. A significant departure resides, however, in the provision of but a single flow line 68 extending from the lower end of the inner container 14 of the storage vessel 11, through the vacuum voids of the vessel and sump and through the peripheral wall of the sump container 46 into the interior thereof. Line 68 is terminated in a single valve 69 disposed at the level of liquefied gas in the sump container. As thus disposed a portion of the outlet port of the valve 69 is exposed to the regions of the sump container overlying the liquid therein, while the remaining portion of the outlet port is immersed in the liquid. As a result, vapor above the liquid in the sump can pass through the valve and bubble through the line 68 and liquid in the vessel to the regions overlying same. Moreover, with the present arrangement the liquiefied gas may be delivered from the storage vessel to the sump without necessitating an equalizing line. The present embodiment of course possesses the advantages of valve access and thermal insulating characteristics of the previous embodiment.

What is claimed is:

1. In a cryogenic flow system of a type including a storage vessel having an inner container for liquefied gas and an outer jacket about the inner container defining a vacuum void therebetween, flow line means extending from the inner container of said vessel, and a pump for effecting flow of liquefied gas from the inner container of said storage vessel through said flow line means, the combination comprising a sump including an inner container and an outer jacket about the inner container of said sump and defining a sealed void therebetween, said void of said sump communicated with said void of said vessel, said flow line means extending through said void of said vessel and said void of said sump into the inner container of said sump, valve means disposed within the inner container of said sump and connected to said flow line means, and means associated with said pump and said sump for removably supporting said pump in a position wherein a portion of said pump including a pumping head thereof extends into the interior of said inner container of said sump.

2. A cryogenic flow system comprising a storage vessel having an inner container for liquefied gas and an outer jacket about the inner container defining a vacuum void therebetween, a sump including an inner container and an outer jacket about the inner container of said sump defining a sealed void therebetween, said inner container of said sump having a top wall with an opening extending therethro'ugh, a conduit communicably secured between the void of said vessel and void of said sump, flow line means extending from the inner container of said vessel through said void of said vessel, said conduit, and said void of said sump into the interior of the inner container of said sump, valve means disposed Within the inner container of said sump and connected to said flow line means, and a pump removably mounted upon the top wall of the inner container of said sump, said pump having a portion with a pumping head at its end extending through said opening of said top wall to a position adjacent the bottom of the inner container of said sump.

3. A cryogenic flow system according to claim 2, further defined by said flow line means including a supply line extending from the lower end of the inner container of said vessel and an equalizer line extending from the upper end of the inner container of said vessel, and by said valve means including a supply valve connected to said supply line having an outlet port communicated with as the lower region of the inner container of said sump, and an equalizer valve connected to said equalizer line having an outlet port communicated with the upper region of the inner container of said sump.

4. A cryogenic flow system according to claim 2, further defined by said flow line means comprising a flow line extending from the lower end of the inner container of said vessel, and by said valve means comprising a valve connected to said flow line having an outlet port disposed at a predetermined level of the inner container of said sump to which liquid rises therein, portions of the outlet port of said valve being respectively disposed above and below said predetermined level.

5. A cryogenic flow system compirsing an upright storage vessel including an inner container for liquefied gas and an outer jacket about the inner container defining a vacuum void therebetween, a sump including an inner container and an outer jacket about the inner container of said sump defining a sealed void therebetween, said inner container of said sump having a top wall with an opening extending therethrough, said sump disposed subjacent the jacket of said vessel, a pair of sleeves extending through said top wall of the inner container of said sump, a conduit communicated at one end with said void of said vessel and at the other end with said void of said sump, supply and equalizer lines respectively extending from the lower and upper ends of the inner container of said vessel through the void of said vessel, said conduit, the void of said sump, and into the interior of the inner container of said sump, supply and equalizer valves disposed within the inner container of said sump and respectively connected to said supply and equalizer lines, said supply and equalizer valves respectively having outlet ports communicating with lower and upper regions of the interior of the inner container of said sump, said supply and equalizer valves having control stems extending through said sleeves exteriorly of the inner container of said sump, and a pump having a support flange at an intermediate position thereof with a depending portion extending from said flange having a pumping head at its end, said pump disposed with said flange engaging and removably secured to the top wall of the inner container of said sump about the opening thereof and said depending portion extending through said opening into the inner container of said sump.

6. A cryogenic flow system comprising an upright storage vessel including an inner container for liquefied gas and a jacket about the inner container defining a vacuum void therebewteen, inlet and vent lines respectively communicated with the lower and upper ends of said inner container and extending through said void to positions exteriorly of said vessel, a fitting adapted for con nection .to a source of liquefied gas, a vent valve terminating said vent line, a fill valve connecting said fitting to said inlet line, a cross-over valve connecting said fitting to said vent line, a sump including an inner container and an outer jacket about the inner container of said sump defining a sealed void therebetween, said inner container of said sump having a top wall with an opening extending therethrough, a conduit communicably secured between the void of said vessel and void of said sump, flow line means extending from the inner container of said vessel through the void of said vessel, said conduit, and said void of said sump into the interior of the inner container of said sump, valve means disposed within the inner container of said sump and connected to said flow line means, a pump removably mounted upon the top wall of the inner container of said sump, said pump having a depending portion with a pumping head at its end extending through said opening of said top wall, said pumping head having an outlet, a heat exchanger having an inlet and an outlet, means including a pressure switch conmeeting the outlet of said pump to the inlet of said heat exchanger, said pressure switch coupled in controlling relation to said pump to deenergize same in response to a predetermined pressure, means circulating heated fluid through said heat exchanger, and a valve connected to the outlet of said heat exchanger to control the flow of gas therefrom.

7. A cryogenic flow system according to claim 6,

further defined by said flow line means including supply and equalizer line respectively communicating with the lower and upper ends of the inner container of said vessel, and by said valve means including a supply valve connected to said supply line having an outlet port communicated with the lower region of the inner container of said sump and an equalizer valve connected to said equalizer line having an outlet port communicated with the upper region of the inner container of said sump.

8. A cryogenic flow system according to claim 6, further defined by said flow line means comprising a flow line communicating with the lower end of the inner container of said vessel, and by said valve means comprising a control valve connected to said flow line having an outlet port disposed at a predetermined level of the inner container of said sump to which liquid rises therein, portions of the outlet port of said control valve being respectively disposed above and below said predetermined level.

References Cited by the Examiner UNITED STATES PATENTS 1,878,317 9/1932 Picard 62-53 2,516,218 7/1950 Kerr 62-52 2,705,873 4/1955 Bonnaud 62-55 3,123,983 3/1964 Sliepcevich 62-55 ROBERT A. OLEARY, Primary Examiner.

L. L. KING, Assistant Examiner.

Claims

1. IN A CRYOGENIC FLOW SYSTEM OF A TYPE INCLUDING A STORAGE VESSEL HAVING AN INNER CONTAINER FOR LIQUEFIED GAS AND AN OUTER JACKET ABOUT THE INNER CONTAINER DEFINING A VACUUM VOID THEREBETWEEN, FLOW LINE MEANS EXTENDING FROM THE INNER CONTAINER OF SAID VESEL, AND A PUMP FOR EFFECTING FLOW OF LIQUEFIED GAS FROM THE INNER CONTAINER OF SAID STORAGE VESSEL THROUGH SAID FLOW LINE MEANS, THE COMBINATION COMPRISING A SUMP INCLUDING AN INNER CONTAINER AND AN OUTER JACKET ABOUT THE INNER CONTAINER OF SAID SUMP AND DEFINING A SEALED VOID THEREBETWEEN, SAID VOID OF SAID SUMP COMMUNICATED WITH SAID VOID OF SAID VESSEL, SAID FLOW LINE MEANS EXTENDING THROUGH SAID VOID OF SAID VESSEL AND SAID VOID OF SAID SUMP ONTO THE INNER CONTAINER OF SAID SUMP, VALVE MEANS DISPOSED WITHIN THE