Fuel deoxygenation systems

1. A fuel deoxygenation system for an aircraft, comprising:

a hydrocarbon recycler configured to recycle hydrocarbon vapors into liquid fuel, including:

a housing that partially defines an ullage channel configured to fluidly communicate with both an ullage of an aircraft fuel tank and a vent, wherein the housing partially defines a hydrocarbon recirculation channel configured to fluidly communicate with a liquid portion of the fuel tank; and

a membrane defining a sealing wall between the ullage channel and the hydrocarbon recirculation channel such that the membrane is in fluid communication with both the ullage channel and the hydrocarbon recirculation channel, wherein the membrane is configured to be permeable to hydrocarbons such that hydrocarbons in the ullage channel can pass through the membrane to the hydrocarbon recirculation channel and oxygen in the ullage channel passes through to be vented.

2. The system of claim 1 , wherein the membrane is a reverse selective membrane.

3. The system of claim 1 , further comprising a sparging gas supply in fluid communication with the liquid portion of the fuel tank for supplying a sparging gas to the liquid fuel.

4. The system of claim 3 , wherein the sparging gas supply includes an electro-chemical converter to produce sparging gas onboard the aircraft.

5. The system of claim 3 , wherein the sparging gas supply is in fluid communication with the fuel tank through the hydrocarbon recirculation channel to sweep the hydrocarbon recirculation channel.

6. The system of claim 1 , further comprising a fuel tank inerting system in fluid communication with the ullage of the fuel tank to provide the ullage with an inerting gas.

7. The system of claim 1 , further comprising a sparging gas separator disposed between the hydrocarbon recycler and the vent configured to recirculate sparging gas to the system and to pass oxygen to the vent.

8. The system of claim 1 , further comprising a prime mover disposed in fluid communication with the hydrocarbon recirculation channel to pressurize the hydrocarbon gas to flow to the liquid portion of the fuel tank and bubble into the liquid fuel.

9. The system of claim 1 , further comprising an ullage prime mover disposed in fluid communication with the ullage and configured to pressurize ullage gas to flow to the hydrocarbon recycler.

10. A method for deoxygenating fuel in an aircraft, comprising:

sparging a liquid fuel of a fuel tank with a sparging gas to displace oxygen from the liquid fuel into an ullage of the fuel tank to create an ullage gas;

separating hydrocarbons from the ullage gas;

venting the ullage gas containing oxygen after separating hydrocarbons from the ullage gas; and

recirculating the hydrocarbons into the liquid fuel.

11. The method of claim 10 , wherein the sparging gas is an inert gas.

12. The method of claim 11 , wherein the sparging gas is nitrogen.

13. The method of claim 12 , wherein separating hydrocarbons includes passing the ullage gas over a reverse-selective membrane that is configured to permeate hydrocarbons and not oxygen.

14. The method of claim 10 , further comprising separating the sparging gas from the ullage gas before venting the ullage gas.

15. The method of claim 14 , further comprising recirculating the sparging gas to the liquid fuel.

16. The method of claim 10 , wherein the sparging gas serves to inert the ullage of the fuel tank.