Steam pressure regulator for cryogenic liquid storage tanks and tanks so that

Description

CLAIM OF PRIORITY

[0001] This application claims the benefit of U.S. Provisional Application No. 62 / 785,508, filed December 27, 2018.FIELD OF THE DISCLOSURE

[0002] The present disclosure relates generally to systems and methods for regulating vapor pressure in a cryogenic liquid storage tank during the fill process. More particularly, the present disclosure relates to heat exchangers for cryogenic liquid storage tanks that assist in regulating vapor pressure during the fill process.

[0003] A cryogenic liquid storage tank may include a top fill circuit or a bottom fill circuit. Both of these circuits drastically change the vapor pressure within the tank during the fill process. Thus, tanks utilizing these circuits require multiple valves, along with manual operation of these valves, in order to find a balance in vapor pressure during filling of the tank. That is, the person filling the tank must monitor the pressure within the tank and adjust the throttling of the fill pipe valves accordingly.

[0004] There remains a need for fill systems and tanks with vapor pressure regulation.SUMMARY OF THE DISCLOSURE

[0005] The invention relates to a cryogenic liquid storage tank in accordance with claim 1 and to a method of filling the tank in accordance with claim 4.BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Fig. 1 illustrates one embodiment of a storage tank having a vapor pressure regulator in accordance with the present disclosure. DETAILED DESCRIPTION OF EMBODIMENTS

[0007] Fig. 1 illustrates an implementation of a storage tank 100. In the illustrate embodiment, the storage tank 100 is a vertical storage tank. In other embodiments, the storage tank 100 may be a horizontal storage tank. The storage tank 100 is a cryogenic liquid storage tank. The storage tank 100 includes an inner vessel 102. The inner vessel 102 is enclosed by an outer vessel 104. The inner vessel 102 can enclose an interior chamber 106. The inner vessel 102 is joined to the outer vessel 104 by an inner vessel support member 105. The inner vessel support member 105 may be connected, at its top end, to an outer component (for example, outer knuckle or outer joint) 107 or to an outer vessel. The inner chamber 106 receives the liquefied gas through a fill pipe 108, stores the liquefied gas, and provides fluid to a use device (for example, a laser cutter, a welder, a food refrigeration device, or any other suitable device) through a withdrawal pipe 110. The fill and withdrawal pipes may be any suitable conduit for conveying or allowing the flow of fluid therethrough. Excess vapor can be exhausted through a vent line 112. The fill pipe 108, the withdrawal pipe 110, and the vent line 112 pass through the inner vessel support member 105, which is open from both top and bottom. In one implementation, the stay and support members can be tubes. In some other implementations, the members can be other types of similar structures, such as passages, pipes, or the like. The cross-sections of these tubes and other structures can have various shapes, such as a circle, ellipsis, square, triangle, pentagon, hexagon, polygon, and other shapes.

[0008] The tank 100 is employed to store cryogenic liquids, wherein the liquids may be liquefied gases. For example, the cryogenic liquids can be at least one of nitrogen, helium, neon, argon, krypton, hydrogen, methane, liquefied natural gas, and oxygen, although other types of gases are within the scope of this disclosure.

[0009] The tank 100 includes a heat exchanger 114 that has a heat exchanger passageway therethrough. The heat exchange passageway is in fluid communication with the fill pipe 108 so that cold liquid coming in through fill pipe 108 flows through the heat exchanger 114. The heat exchanger 114 includes an outlet end 116 in fluid communication with the heat exchanger passageway, wherein the liquid 120 is dispensed from the outlet end and into the vessel 102 to fill the tank 100. The outlet end 116 is positioned or located so as to dispense the incoming liquid into an existing liquid volume of the tank, which is similar to a traditional bottom fill system.

[0010] The heat exchanger 114 may be the illustrated coiled heat exchanger 118. In other embodiments, the heat changer may be a serpentine heat exchanger. The heat exchanger 114 is located in the vessel 102, and is located in the ullage or headspace of the tank. As the cold incoming liquid flows through the heat exchanger 114, the heat exchanger condenses the hotter gas around, thus reducing the vapor pressure within the tank 100. Additionally, as liquid 120 is dispensed out of the outlet end 116 of the heat exchanger near the bottom of the vessel 102, vapor pressure builds within the tank 100, similar to that of a traditional bottom fill. As the level of liquid 120 increases, the gas space compresses, and the pressure in the tank rises as a result. The heat exchanger, e.g. coil, serpentine or tube, can be differently sized and shaped depending on the tank and the type of liquid the tank is designed to store. The heat exchanger may be designed so that the pressure reducing effect from the heat exchanger and the pressure increasing effect from the liquid level increase cancel each other out. This may result in the tank maintaining its pre-fill vapor pressure consistently throughout the filling process.

[0011] The heat exchanger may eliminate the need to monitor the pressure and the need to adjust the throttling of the fill line valves. Because the valves do not need to be throttled, they can be removed, saving cost and reducing potential leak points on the tank. Also, since the operator filling the tank will not need to closely monitor the pressure, he / she can allocate more time to other aspects of the filling process, such as safety.

[0012] While the preferred embodiments of the disclosure have been shown and described, it will be apparent to those skilled in the art that changes and modifications may be made therein without departing from the scope of the following claims.

Claims

1. A cryogenic liquid storage tank (100), comprising: a vessel (102) for containing a cryogenic liquid, said vessel (102) including an ullage; a fill pipe (108) in communication with the vessel (102) wherein the vessel (102) is filled with incoming cryogenic liquid via the fill pipe (108); a heat exchanger (114) located within the ullage of the vessel (102), the heat exchanger (114) having a coiled or serpentine heat exchanger passageway in fluid communication with the fill pipe (108) so that incoming cryogenic liquid flows through the coiled or serpentine heat exchanger passageway, wherein the heat exchanger (114) is configured so that when cryogenic liquid flows through the coiled or serpentine heat exchanger passageway during filling of the vessel (102) the heat exchanger (114) condenses hotter gas around the heat exchanger (114) so as to reduce vapor pressure within the tank (100); and the heat exchanger includes an outlet end (116) in fluid communication with the coiled or serpentine heat exchanger passageway, the outlet end (116) being located below the ullage and being configured to dispense incoming cryogenic liquid into an existing volume of the liquid in the vessel (102).

2. The cryogenic liquid storage tank (100) of claim 1 wherein the pressure reducing effect of the heat exchanger (114) and the pressure increasing effect from the liquid level (120) increase cancel each other out so that the tank (100) maintains its pre-fill vapor pressure consistently throughout a filling process.

3. The cryogenic liquid storage tank (100) of claim 1 wherein the heat exchanger (114) assists in maintaining a selected vapor pressure within the tank (100).

4. A method of filling a cryogenic liquid storage tank (100) according to any one of claims 1-3 with a cryogenic liquid, the method comprising: flowing cryogenic liquid through a fill pipe (108) into a vessel (102) of the tank (100); flowing the cryogenic liquid through a coiled or serpentine passageway of a heat exchanger (114) located within an ullage of the tank (100) so as to condense hotter gas around the heat exchanger (114) so as to reduce vapor pressure within the tank (100); ; and dispensing the cryogenic liquid out of an outlet end (116) of the heat exchanger and into an existing volume of the liquid in the vessel of the tank, the outlet end (116) being located below the ullage.

5. The method of claim 4 wherein the pressure reducing effect of the heat exchanger (114) and the pressure increasing effect from the liquid level (120) increase cancel each other out so that the tank (100) maintains its pre-fill vapor pressure consistently throughout a filling process.