US3541803A - Cryogenic liquid storage system - Google Patents

Description

Nov. 24, 1970 F. s. YQUNG QRYOGENIC LIQUID STORAGE SYSTEM 2 Sheets-Sheet l Filed Sept. 1 1968 IIIIJ 1|.lI||....L

Farr/7e 9 J sy% ff M fizz Z Arr mver NOV. 24, 1970 s, YOUNG 3,541,803

GRYOGENIC LIQUID STORAGE SYSTEM Filed Sept. 18, 1968 2 Sheets-Sheet 2 r Z 3% 49 8 x -39 Farr/7e J. you/79' United States Patent 3,541,803 CRYOGENIC LIQUID STORAGE SYSTEM Farrile 5. Young, Houston, Tex., assignor, by mesne assignments, to Gulf Central Pipeline Company, Chicago, 11]., a corporation of Delaware Filed Sept. 18, 1968, Ser. No. 760,541 Int. Cl. F17c 7/02; F1711 3/00 US. Cl. 62-45 8 Claims ABSTRACT OF THE DISCLOSURE This patent dicloses a system for storing volatile liquids, and particularly ammonia, in Which the temperature of the earth is utilized to maintain the stored fluid in the liquid stage.

This invention relates to a storage system for volatile liquids.

It is an object of this invention to provide a system for storing volatile liquids, such as anhydrous liquid ammonia, adjacent a pipeline.

Another object is to utilize underground temperature to maintain the vapor pressure of a stored liquid at a low level.

Another object is to provide a system of storing volatile liquids in which only liquids are transferred to and from storage.

Another object is to provide a simple system for transferring a volatile liquid to and from storage in which much of the control equipment is used in transferring of liquid in both directions.

Another object is to provide a system for storing a volatile liquid utilizing high pressure pumps in which the exertion of excessive high pressures on lines due to blockage is prevented.

Other objects, features and advantages of this invention will be apparent from the drawings, the specification and the claims.

In the drawings, wherein illustrative embodiments of this invention are shown, and wherein like reference numerals indicate like parts:

FIG. 1 is a schematic illustration of one form of this invention;

FIG. 2 is a schematic illustration of the wiring diagram of the high pressure pump and two valves; and

FIG. 3 is a diagrammatic illustration of a modification of the system of FIG. 1.

This invention is directed toward the storage of anhydrous liquid ammonia, but may be utilized with any other desired volatile liquid.

In order to maintain ammonia in the liquid state, the highest historical ground temperature at the site is taken into consideration in the design of the storage tank. Thus, in one midwestern area the annual ground temperature data varies from a range of approximately 40 to approximately 75. This will give a range of vapor pressure of anhydrous ammonia from approximately 59 p.s.i.g. to 126 p.s.i.g. Thus a storage tank for use in this area should be capable of withstanding a bursting pressure of at least 126 p.s.i.g. Of course, it is preferred to include a suitable safety factor. Such a storage tank is shown at 10 and is shown to be buried below ground to shield it from direct rays of the sun and to take advantage of the heat sink characteristics of the earth. The storage tank has a suitable manhole indicated at 11 and a relief valve indicated at 12.

The storage tank is buried adjacent the pipeline 13 which is utilized to convey the ammonia between remote locations. The storage tank, which may take the form of a number of separate tanks, is utilized to store the am- Patented Nov. 24, 1970 monia until it is needed and then return the ammonia to the pipeline.

The storage tank may be an unfired pressure vessel constructed of rolled plates or spiral welded strips.

In accordance with this invention, a control conduit indicated generally at 14 is provided. This conduit is connected to the pipeline through a first conduit 15, and to the storage tanks through a second conduit 16 and a third conduit 17. The control conduit meters the flow of liquid into the storage tank and insures that nothing but liquid is transferred. The control conduit is also utilized in returning liquid from the storage tank to the pipeline and insures that only liquid is returned to the pipeline.

At the end of the control conduit, which is connected to the first conduit 15, a valve 18 is provided. This is a motor operated open-and-shut valve which is manipulated from the control station indicated generally at 19. This valve might be considered a master valve to block the remainder of the system from the pipeline.

Adjacent the open-and-shut valve 18 is a metering valve 21 which is utilized to meter flow of liquid from the pipeline 13 into the storage tank 10. This valve is also preferably a motor operated valve manipulated from the control station 19. The operator Will normally control this valve to provide for a slow filling of the storage tank 10 to give ample time for the vapors in the storage tank to liquefy as the storage tank is filled.

The valve 18 is preferably automatically controlled in response to conditions in the control line as sensed by the sensing device indicated generally at 22 to close in the event of a line break or the failure of valve 21 to close. The valve 18 is also sensitive to conditions in storage tank 10 as indicated by the sensing device 23 to auto matically close on a selected high liquid level in the tank, or in the event of pressure above a selected level in the tank.

A meter 24 is provided in the control line to meter flow of fluid therethrough and to transmit a signal to a suitable readout device in the control station 19 indicating flow therethrough.

A back pressure valve 25 is provided in the control conduit 14 which is sensitive through line 26 to the pressure within the control conduit upstream of the valve. The valve 25 will be set to maintain a back pressure above the boiling point of the fluid within the line to insure that the fluid passing through the valve and through the meter 24 is in the liquid state.

Downstream of the back pressure valve 25 is a two-way valve indicated generally at 27, which has a single inlet 28 and two outlets 29 and 31. The outlet 29 is connected to line 16 to provide for flow from the pipeline through line 16 into the storage tank. If desired, a manual control valve 32 may be provided in the line 16 which would be open during transfer of liquid to the storage tank.

The portion of the system thus far described would be used in transferring liquid from the pipeline 13 to the storage tank 10. This would be accomplished first by opening valve 18 to its fully open position and then setting valve 21 at the desired setting to meter liquid through the control conduit 14. This liquid would be driven by the pressure in the pipeline which would normally range upwardly of 600 p.s.i. g. for ammonia. To insure that nothing but liquid passed through the meter 24, the back pressure valve 25 would be set to maintain a back pressure in excess of the vapor pressure of the liquid.

The valve 27 would be positioned to pass fluid from the inlet 28 through the outlet 29 and thence into the storage tank.

A separate line is preferably used to remove liquid from the storage tank, such as the third conduit 17. A pump 33 is provided in this line to pump liquid from the J storage tank to the control conduit 14. If desired, flow through the line 17 may be controlled by a manual valve 34 or the valve 34 may be open and control be obtained through a motor valve 35 manipulated from the control station 19.

During return of liquid to the pipeline the control valve 21 is closed and the line 17 is connected to the control conduit between the control valve 21 and the meter 24. The two-way valve 27 is positioned to establish communication between inlet 28 and outlet 31. Thus fluid will flow through the meter 24 and against the back pressure of back pressure valve 25 to insure that only liquid passes through the meter 24 and is returned to pipeline 13.

The outlet 31 of valve 27 is connected to a loop conduit 36. This conduit is connected to the control conduit between valves 18 and 21.

A high pressure pump 37 is preferably provided in the loop 36. It will be apparent, however, that pump 33 could be the only pump utilized to return the liquid.

During return of liquid from the storage tank to the pipeline the valve 21 is positioned full-closed and the valve 18 full-open. If control of the returning liquid is desired, the valve 35 is set for the desired control. Pump 33 transfers liquid from the storage tank 10 through line 17 to the control conduit 14 to pass through the meter 24 against the pressure of back pressure valve 25. The fluid flows through the valve 27 and is picked up by pump 37 which increases its pressure to a pressure necessary to introduce it into pipeline 13. The output from the pump 37 passes through loop conduit 36 to the control conduit between valves 18 and 21 and thence through valve 18 and conduit 15 to the pipeline 13.

Referring now to FIG. 2, a preferred safety system is shown. During transfer of fluid from the pipeline to storage, it is desired that valve 21 be capable of opening only when valve 18 is open. A source of current for operating the controls of these two valves is shown at 38 and 39. The lines 38 and 39 are connected to the control 41 for valve 18. Thus valve 18 is opened by actuation of the switch 42 in line 38. Branch lines 43 and 44 extend from lines 38 and 39 to the control 45 for valve 21. A switch 46 in line 44 controls operation of valve 21. As switch 42 must be closed before current will pass through switch 46 when closed, it is apparent that valve 21 can only be operated when valve 41 is in open position.

During return of fluid from the storage tank to the pipeline, it is desirable that means he provided to prevent any malfunction which would result in the high pressure pump 37 pumping against valve 18 in closed position. In

order to prevent this possibility, branch line 43 is extended to the control 47 for the pump 37 and a breach line 48 extends from the line 38 to the control 47. A suitable switch 49 therein controls operation of the pump. Thus switch 42 must be closed to open valve 18 before the pump 37 can be operated.

Referring now to FIG. 3, a modification of the system of FIG. 1 is shown in which the pressure drop across valve 21 of the FIG. 1 system is utilized. Thus valve 21 is omitted and the motor 51 is substituted in its place. As liquid passes through the motor 51, the shaft 52 is rotated to drive the compressor 53. The compressor 53 receives vapors from the top of storage tank 10 through line 54. After the vapors are compressed and liquefied in compressor 53, they are returned to the tank through line 55. The remainder of the system would be as shown in FIG. 1. In this system, the vapors from the tank would be compressed, utilizing the energy passing through motor 51 instead of being raised in pressure in the storage tank to a value above the vapor pressure to force them into solution.

The foregoing disclosure and description of the invention are illustrative and explanatory thereof and various changes in the details of the illustrated construction may be made within the scope of the appended claims without departing from the spirit of the invention.

What is claimed is: 1 4

1. A system for storing volatile liquid comprising:

a pipeline conveying volatile liquid at an elevated pressure,

a storage tank buried below ground level and capable of withstanding a burst pressure in excess of the vapor pressure of the stored liquid at the highest ground temperature historically recorded at the site of the storage tank,

a conduit connected to the pipeline and storage tank,

means in the conduit for reducing the pressure of the liquid as it travels from the pipeline to the tank, and

a valve positioned in the conduit between the storage tank and pressure-reducing means,

said valve opening in response to inlet pressure in excess of vapor pressure of liquid at the inlet of said valve whereby only liquid can pass through said valve.

2. The system of claim 1 in combination with conduit means for returning liquid to said pipeline from said storage tank,

a pump in said last-mentioned conduit,

a second valve downstream of said pump,

said second valve opening in response to inlet pressure in excess of vapor pressure of liquid at the inlet to said second valve whereby only liquid can pass said second valve.

3. A system for storing volatile liquid comprising:

a pipeline conveying a volatile liquid at an elevated pressure,

a storage tank buried below ground level and capable of withstanding a vapor pressure in excess of the vapor pressure of the liquid at the highest ground temperature historically recorded at the site of the storage tank,

a control conduit,

a first conduit interconnecting the control conduit and the pipeline,

an open-and-shut valve in the control conduit controlling flow in both directions,

a metering valve in said control conduit for metering flow to and from the storage tank,

a meter in said control conduit for metering flow to and from said storage tank,

back pressure valve means in the control conduit opening in response to inlet pressure in excess of the vapor pressure of liquid at the back pressure valve inlet whereby only liquid can bypass said valve means,

two-way valve means having its inlet connected to one end of the control conduit,

a second conduit interconnecting one outlet of the twoway valve means and the storage tank,

a loop conduit interconnecting the other outlet of the two-way valve means with the control conduit between the metering valve and the open-and-shut valve,

a third conduit interconnecting the storage tank and the control conduit between the meter and both of the metering valve and open-and-shut valve,

and pump means in said third conduit.

4. The system of claim 3 wherein a high pressure pump is positioned in said loop conduit.

5. The system of claim 3 wherein a metering valve is provided in said third conduit.

6. The system of claim 3 wherein a metering valve is provided in said third conduit,

control means for said open-and-shut valve and said metering valve in said third conduit interlocking to permit opening of said metering valve only when said open-and-shut valve is open.

7. The system of claim 3 wherein a high pressure pump is provided in said loop conduit, and control means are provided for said open-and-shut valve and said high pressure pump permitting operaiton of said pump only when said open-and-shut valve is open.

6 8. A system for storing volatile liquid comprising: References Cited a gipriline conveying volatile liquid at an elevated pres- UNITED STATES PATENTS a storage tank buried below ground level and capable 3366362 8/1966 Moragne 62*54 of withstanding a burst pressure in excess of the 31276631 10/1966 9 62 45 vapor pressure of the stored liquid at the highest 5 3,359,739 12/1967 Blshop 62 45 X ground temperature historically recorded at the site 3,453,836 7/1969 Kerr 62 45 of the storage tank,

a conduit connected to the pipeline and storage tank,

and

a motor in the conduit for reducing the pressure of 10 the liquid as it travels from the pipeline to the tank, 55, 402

said motor providing power for a refrigeration system liquefying vapors from said storage tank.

ALBERT W. DAVIS, JR., Primary Examiner

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