|Publication number||US2871669 A|
|Publication date||Feb 3, 1959|
|Filing date||Dec 5, 1956|
|Priority date||Dec 5, 1956|
|Publication number||US 2871669 A, US 2871669A, US-A-2871669, US2871669 A, US2871669A|
|Inventors||Mann Douglas, Macinko John|
|Original Assignee||Mann Douglas, Macinko John|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (3), Referenced by (21), Classifications (9)|
|External Links: USPTO, USPTO Assignment, Espacenet|
Feb. 3, 1959 N D. MANN ETAL 2,871,669
. RADIATION SHIELD CIRCULATION SYSTEM FOR LARGE LIQUEFIED GAS STORAGE CONTAINERS Filed Dec. 5, 1956 k J INVENTORS DOUGLAS MAN/V ATTORNEY'ZS Unite RADIATION SHIELD CIRCULATION SYSTEM FOR LARGE LIQUEFIED GAS STORAGE CONTAINERS Douglas Mann and John Macinko, Boulder, Colo., as-
slgnors to the United States of America as represented by the Secretary of the Navy The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.
The invention relates to systems for holding large storage containers at extremely low temperatures.
It is customary in storage containers for liquefied gases, for example, to employ axially concentric shells, with the cooled liquid in the inner shell and suitable heat insulation separating the shells. Two shells are usually found adequate for liquefied oxygen or nitrogen but, in the case of liquefied hydrogen or helium, at least three shells are desirable, the outer shell being at room temperature and the intermediate shell at some reduced temperature adequate to prevent too rapid heat leak to the low temperature liquid. In the case of small storage units, the three shell type is satisfactory where the intermediate shell coolant, such as liquid oxygen, is confined in one section of the heat shield, since the heat path is relatively short and heat is readily conducted to the shield section directly cooled by the refrigerant. In the case of large containers, however, this method is inadequate to maintain the contained liquid at the required low temperatures.
- Generally stated, the invention is directed to a cold liquid storage system capable of maintaining adequate heat insulation in large or small size containers through circulation of a coolant throughout the tank areas under automatic pressure controls.
The objects of the invention, therefore, arev the provision of a circulating cooling system for low temperature maintenance; the provision of a circulating coolant in storage systems which is completely automatic in action; the provision of cooling apparatus for storage containers which is operative for large or small units; and the provision of cooling equipment for large containers which may be applied and utilized at relatively low costs.
Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:
Fig. 1 is a vertical section through the liquid gas storage container;
Fig. 2 is a sectional view of the container taken along line 22'of Fig. l;
, Fig. 3 is a schematic view of the storage container in association with the control apparatus; and
Fig. 4 is a, detail of the restriction in the lower pipes of the coolant circulation system to produce abalancing of fiow in the various pipe lines. Referring to Fig. 1, the storage unit is shown as ates Pat formed of three cylindrical shells 11, 12 and 13, 11 indicating the container for liquefied hydrogen, helium or the like, 12 indicating the container for the intermediate coolant and 13 the outer container which is normally at room temperature. As shown, these shells are spaced uniformly from each other so that, as appears from Fig. 2,
2,871,669 Patented Feb. 3, 1959 axis, numeral 6 indicating a part of the outer shell support, numeral 7 a part of the intermediate shell support and numeral 8 a part of the inner shell support. The cylindrical wall 'of shell 12 is extended, as at 14, beyond the end walls of the shell at both ends to form annular recesses into which are fitted the two tanks 16 and 17 for reception of the coolant liquid such as liquid oxygen. These tanks are similarly shaped, being of cylindrical cross-section with a rounded convexly curved end closure which conforms in shape to the rounded curvature of the intermediate and outside shells, there being provided outlet pipes 18 and 19 at the tank bases, and hydrostatic liquid level gage pipes 20 and 21 and vent pipes 22 and 23, respectively, at the tops of tanks 16 and 17. Inlet pipe 25 with valve 26 is provided for liquid supply to container 11 and inlet pipe 27 with valve 28 for supply of coolant to tank 17. The curved end 30 of tank 16 and 31 of tank 17 support in close contact therewith annular manifold tubes 33 and 34, each tube having a short open pipe, 35 and 36 respectively, adjacent to but displaced from the tank bases for passage of liquid to and from the .tank. These manifold tubes constitute standpipes for reception of coolant from the adjacent tank and delivery of coolant to the pipe network extending through the annular space between the inner and middle shells 11 and 12 and joining the manifold tubes. This network includes the straight pipes 37 parallel to the container axis and displaced uniformly in the coolant space 40 about the inner shell 11. Since the flow path from tank to tank is shorter in the base pipes due to the placement of standpipe inlet-outlet pipes 35 and 36 adjacent the tank bases, liquid restriction devices 41, as shown in Fig. 4, are placed in these base pipes to equalize the coolant flow through all pipes from manifold to manifold. These restrictions may he graduated in size, with the restrictive orifice smaller in the bottommost pipe and increasing, moving up from the container base, so as to insure uniform flow of coolant through all pipes.
The structure, as above described, illustrates a usable container unit for low temperature liquid storage. The control mechanism for maintaining the flow of coolant through the pipe lines will now be described.
Referring to Fig. 3 it will appear that level gage pipe 21) from tank 16 connects to the outlet pipe 18 through a hydrostatic liquid level gage and level gage pipe 21 from tank 17 connects to outlet pipe 19 through the hydrostatic liquid level gage 46. The vent pipes 22 and 23 from tanks 16 and 17, respectively, are connected together through a pressure equalizing solenoid valve 47. Also, these vent pipes are connected to venting spaces through solenoid valves, pipe 22 through vent valve 48 and pipe 23 through vent valve 49. Outlet pipe 18 from tank 16 also connects with pressure actuated electric switch 53 and outlet pipe 19 with a similar pressure switch 52, these pressure switches being similar and consisting of a closed chamber 80 having a flexible diaphragm 81 therein, two opposed contact switch points 82, 83 connected to a common terminal 84, a switch arm 35 movable between the contact points and a connecting rod 36 between the diaphragm and notch arm.
The electric circuit for operating the solenoid valves and electric pressure switches is derived from a power source having terminals 55 and 56, terminal 55 having direct connection to the pressure switches 52 and 53 and terminal 56 connecting these same switches in parallel through a series latching relay 58 containing solenoid 59, the solenoid functioning on energization to cause step-bystep rotation of a latching wheel 60. This latter solenoid circuit also includes, in series, a timing switch 61, which functions, on operation of either pressure switch 52 and 53, to energize solenoid 62 in the pressure equalizing valve 47, opening the same for a time period of about two to five minutes.
The step-by-step latching wheel 60, on rotation by solenoid '59, serves, by'virtue of alternate elevations and depressions 63, 6 4, to move the switch arm 65'," pivoted at66 between con'ta'cts67 and 68, connectionw-ith contact 67 establishing a circuit through solenoid'70 of the solenoid valve 49, closing this valve, valve 43 simultaneously opening, and connection with contact fi establishing a circuit through solenoid 71 of vent valve 48, closing this valve and simultaneously opening vent valve 49.
The operation of the radiation shielding unit is as follows, it beingassumed that the insideshell 11 hasa supply of liquid hydrogen orhelium, and the tank's'16 and 17 a supply of coolant'such as liquid oxygen in amount sufiicient to fill at least one ofisaid tanks, for
descriptive purposes it beingassumed that the coolantisequally contained in both tanks; It is assumed, also, that the vent'valve 48 is closed, vent valve 49 open' and the pressure equalizing valve 47 closed. Under these conditions, heat leak to tank 16 causes evaporation ofthecoolant, the gas evolved pressurizing the liquid in the tank and forcing it through standpipe manifold 33 intolatching relay 58 and thereby closing vent valve 49andopening vent valve 48. At the same time, timing switch 61 opens pressure equalizing valve 47 for a time period of about two to five minutes, as predetermined for best operation, thus bringing about an equalization' of pres sure and levels of the coolant in both tanks. This is necessary in order to insure an adequate supply of coolant in tank 17 for subsequent circulation in thepipe-system, and is possible since the port opening ofequalization valve 47 is large compared to the port opening of either vent valve. On closure of the pressure equalization valve 47, gas pressure begins to build up in tank 17, forcing coolant through the pipe system back to tank 16, thus providing a continuing coolant shield in the intermediate shell space ill. The level of coolant in tank it: rises due to the inflow from tank 17 until at about 100 percent capacity level, pressure switch 53 is closed to bring about actuation of latching relay 5% and timing switch 61, this resulting in closing of vent valve 4-3, opening of vent valve 49 and timed opening of pressure equalizing switch 47. This cycle of changes is continued automatically, thus maintaining an effective low temperature heat shield in intra-shell space 49, a shield which is normally in dependent of the size of the storage unit.
As described, the pressure switches close at about l00 percent inflow of coolant into the associated tank. However, due to loss of coolant, a condition may arise where the coolant supply is inadequate to fill a single tank. To meet this situation, the pressure switches are arranged to make closure contact also at 5 percent of tank supply, so that if the 100 percent pressure switch associated with one tank fails to function, the 5 percent pressure switch of the other tank will make contact at point 82.
Since the timing, latching, and solenoid switches are of conventional construction, these are not detailed in the drawing or description. For example the timing switch may operate on a time clock or similar movement; the latching switch utilizes the magnetic impulse of solenoid 59 to produce'a step movement of wheel 60, and the solenoid switches function to move armatures to actuate valve opening and closing. elements.
Obviously many modifications and variations of the present invention are possible in'the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.
What is claimed is:
l. A heat-shielded storage container for cold substances comprising a structure of at least three closed shells including an inner shell for holding the cold substance, an outer shell normally at room temperature onclosing said-inner shell, and an intermediate shell having opposed ends interposed between the inner andv outer shells and defining a heat shield, liquid holding tanks placed one at each end of the intermediate shell, coolant pipes connecting said tanks and lying between the intermediate and inner shells, means for supplying cold substances to said inner shell and coolant to said tanks, and means for circulating said coolant automatically through said coolant pipes.
2. A heat-shielded storage container for cold sub stances as defined in claim 1, said coolant circulating means comprising a gas vent pipe for each of said tanks, a valve in eachofsaid vent pipes, apipeconnection between said vent pipes at the container side of thevent valves, a pressure equalizing valve in said vent pipe connection, a pressure electric switch connected, to each of said tanks movable to closed position at predetermined pressures in said tanks, a timing switch operable at closure of either of said pressure switches to close the pressure equalizing valve'for a predetermined time period,
and a latching relay operable atsuccessive closuresof said pressure switches alternately to close and open one of said vent valves while simultaneously opening and closing the other of said vent valves. 7 v
3. A heat-shielded storage container for coldsubstances comprising a structure of'at least three closed shellsincluding an inner shell for holding the cold substance, an outer shell normally at room temperature enclosing said inner shell, and an intermediate shell interposed between the inner and outer shells and defining a heat shield, liquid-holding tanks placed one at eachend of the intermediate shell, a standpipe positioned-in each tank and communicating therewith, coolant pipes connecting the said standpipes and extending between the inner andintermediate shells, means for supplying cold substances to said inner shell and coolant to said tanks, andmeans forcirculating coolant automatically through said coolant pipes.
4. A heat-shielded storage container for cold substances as defined in claim 3, said standpipe including an an nular manifold having a diameter approximating that of the tank and a port therein positioned adjacent the base thereof and communicating with the tank interior;
5. The heat-shielded storage container-for cold substances as defined in'claim 4, said coolant pipes extending parallel to the axis of said inner shell and spaced uniformly thereabout to form an overall heat shield for said inner shell.
6. The heat-shielded storage container for cold substances as'defined in claim 5, and means inside said coolant pipes which connect the port section of'said manifolds for balancing liquid'fiow through all of said coolant pipes.
7. The heat-shielded storage container for cold substances as defined in claim 6, said pipe :fiow balancing means comprising orifice restrictions inside said pipes.
8. In-a'heat-shielded storage container for cold substances including an elongated closed shell -for cold substance storage, coolant tanks at each end of said shell, coolant pipes between said tanks with said pipes in overlying contiguity with the shell Wall, and ports for supply of cold substance to said shell and coolant to said tanks, means for obtaining automatic circulation of coolant through saidcoolant' pipes comprising a gasvent pipefor each of said tanks, a valve in each of said vent pipes, a pipe connection betweensaid vent pipesat the container side of the vent valves, av pressure equalizing valve in. said vent pipe connection, a pressure electric switch connected to each of said tanks movable to closed 5 position at predetermined pressures in said tanks, a timing switch operable at closure of either of said pressure switches to close the pressure equalizing valve for a predetermined time period, and a latching relay operable at successive closures of said pressure switches alternate- 1y to close and open one of said vent valves while simultaneously opening and closing the other of said vent valves.
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|U.S. Classification||62/48.3, 62/157, 220/592.1, 220/901, 220/560.12|
|Cooperative Classification||F17C3/10, Y10S220/901|