Vapor pressure regulator for cryogenic liquid storage tanks and tanks including the same

1. A cryogenic liquid storage tank, comprising:

an inner vessel for containing a cryogenic liquid, the vessel having a top end portion, a bottom end portion, and a headspace at the top end portion;

a fill pipe located at the top end portion of the vessel and in communication with the vessel, wherein the vessel is filled with incoming cryogenic liquid via the fill pipe;

a withdrawal pipe located at the bottom end portion of the vessel; and

a heat exchanger located within the vessel, the heat exchanger having a coiled or serpentine heat exchanger passageway in fluid communication with the fill pipe so that incoming cryogenic liquid coming in through the fill pipe flows through the coiled or serpentine heat exchanger passageway, the coiled or serpentine heat exchanger passageway located in only the headspace of the vessel, wherein the incoming cryogenic liquid flows through the coiled or serpentine heat exchanger passageway during filling of the vessel and the heat exchanger condenses gas within the headspace; and

the heat exchanger includes an outlet end having a passageway that extends downward from the coiled or serpentine heat exchanger passageway, the outlet end's passageway being in fluid communication with the coiled or serpentine heat exchanger passageway so that incoming cryogenic liquid flows from the coiled or serpentine heat exchanger passageway, though the outlet end's passageway and dispensed into the bottom end portion of the vessel.

2. The cryogenic liquid storage tank of claim 1 wherein the outlet end's passageway is positioned to dispense the incoming cryogenic liquid into an existing volume of liquid in the inner vessel.

3. The cryogenic liquid storage tank of claim 1 wherein the outlet end is located below the headspace.

4. The cryogenic liquid storage tank of claim 1 wherein the outlet end is configured to dispense cryogenic liquid into an existing volume of the liquid in the vessel.

5. The cryogenic liquid storage tank of claim 1 wherein the heat exchanger assists in maintaining a selected vapor pressure within the inner vessel of the tank.

6. A method of filling a cryogenic liquid storage tank with a cryogenic liquid, the method comprising:

flowing cryogenic liquid into a fill pipe of the tank;

flowing the cryogenic liquid through a coiled or serpentine passageway of a heat exchanger within the tank, wherein the coiled or serpentine passageway is located only within a headspace of the tank;

condensing gas with the headspace with the heat exchanger as cryogenic liquid flows through the heat exchanger;

flowing the cryogenic liquid out of the coiled or serpentine passageway of the heat exchanger and through an outlet passageway of the heat exchanger; and

flowing the cryogenic liquid out of the outlet passageway of the heat exchanger and into the tank.

7. The method of claim 6 , further comprising withdrawing cryogenic liquid from the tank through a withdrawal pipe located at a bottom portion of the tank.