System and method for transferring natural gas for utilization as a fuel
Natural gas is produced when LNG that is contained in an insulated LNG cargo tank(s) of a non-self-propelled LNG carrier (i.e., a barge) evaporates as a result of heat leakage through the walls of the insulated cargo tank(s). The natural gas is transferred from the barge to a tugboat or a towboat that is equipped with natural gas burning engines through a flexible gas transfer assembly so that the tugboat is powered by the natural gas fuel. The pressure in the cargo tank(s) on the barge is, therefore, effectively managed to prevent or substantially reduce the buildup of pressure within the LNG cargo tank(s). The LNG can then be contained within the LNG cargo tank(s) for an appropriate period of time and can be delivered at an appropriate and acceptable equilibrium pressure and temperature.
1. A system for transferring natural gas from a first vehicle to a second vehicle, the system comprising:
a flexible transfer means through which natural gas is transferred from a first vehicle to a second vehicle, the flexible transfer means having a first end coupled to the first vehicle and a second end coupled to the second vehicle;
a jacket enveloping the transfer means such that a space is formed between the transfer means and the jacket, wherein the space between the transfer means and the jacket is at a pressure that is higher than a pressure of the natural gas in the transfer means; and
a gas that will not support combustion disposed in the space between the transfer means and the jacket.
2. The system of claim 1 , further comprising:
a supply line through which the gas that will not support combustion is supplied to the space between the transfer means and the jacket; and
a pressure switch that monitors the pressure of the gas that will not support combustion in the supply line.
3. The system of claim 2 , wherein the pressure switch closes when the pressure of the gas that will not support combustion in the supply line drops.
4. The system of claim 3 , further comprising an alarm system coupled to the pressure switch.
5. The system of claim 4 , wherein the closing of the pressure switch causes an alarm to be triggered.
6. The system of claim 3 , further comprising a shutdown system coupled to the pressure switch.
7. The system of claim 6 , wherein the closing of the pressure switch causes the shutdown system to shut down the supply of the natural gas to the transfer means.
8. The system of claim 1 , further comprising a self-sealing breakaway connection that couples the transfer means to the first vehicle, such that the transfer means automatically separates from the first vehicle without releasing natural gas upon application of an excessive load.
9. The system of claim 1 , further comprising a self-sealing breakaway connection that couples the transfer means to the second vehicle, such that the transfer means automatically separates from the second vehicle without releasing natural gas upon application of an excessive load.
10. The system of claim 1 further comprising a self-sealing connection that couples the transfer means to the first vehicle, such that the transfer means can be intentionally disconnected from the first vehicle without releasing natural gas.
11. The system of claim 1 , further comprising a self-sealing connection that couples the transfer means to the second vehicle, such that the transfer means can be intentionally disconnected from the second vehicle without releasing natural gas.
12. The system of claim 1 , wherein the gas that will not support combustion comprises an inert gas.
13. The system of claim 1 , wherein the first vehicle and the second vehicle comprise marine vessels.
14. The system of claim 13 , wherein:
the first vehicle comprises a non-self-propelled LNG carrier; and
the second vehicle comprises a tugboat that is adapted to push the non-self-propelled LNG carrier.
15. The system of claim 13 , wherein:
the first vehicle comprises a non-self-propelled LNG carrier; and
the second vehicle comprises a towboat that is adapted to push the non-self-propelled LNG carrier.
16. The system of claim 1 , wherein the first vehicle and the second vehicle comprise land vehicles.
17. The system of claim 16 , wherein:
the first vehicle comprises a railroad tender car; and
the second vehicle comprises a railroad locomotive.
18. A method for transferring natural gas from a first vehicle to a second vehicle, the method comprising:
transferring natural gas from a first vehicle to a second vehicle through a flexible transfer means having a first end coupled to the first vehicle and a second end coupled to the second vehicle;
enveloping the transfer means such that a space is formed around the transfer means;
maintaining the space at a pressure that is higher than a pressure of the natural gas in the transfer means; and
providing a gas that will not support combustion in the space.
19. The method of claim 18 , further comprising the step of monitoring the pressure of the space.
20. The method of claim 19 , further comprising the step of limiting the flow of the gas that will not support combustion when the pressure of the space drops.
21. The method of claim 20 , further comprising the step of triggering an alarm when the pressure of the space drops.
22. The method of claim 19 , further comprising the step of shutting down the supply of the natural gas to the transfer means when the pressure of the space drops.
23. The method of claim 18 , further comprising the step of coupling the transfer means to the first vehicle such that the transfer means automatically separates from the first vehicle without releasing natural gas upon application of an excessive load.
24. The method of claim 18 , further comprising the step of coupling the transfer means to the second vehicle such that the transfer means automatically separates from the second vehicle without releasing natural gas upon application of an excessive load.
25. The method of claim 18 , further comprising the step of coupling the transfer means to the first vehicle such that the transfer means can be intentionally disconnected from the first vehicle without releasing natural gas.
26. The method of claim 18 , further comprising the step of coupling the transfer means to the second vehicle such that the transfer means can be intentionally disconnected from the second vehicle without releasing natural gas.
27. The method of claim 18 , wherein the gas that will not support combustion comprises an inert gas.
28. The method of claim 18 , wherein the first vehicle and the second vehicle comprise marine vessels.
29. The method of claim 28 , wherein:
the first vehicle comprises a non-self-propelled LNG carrier; and
the second vehicle comprises a tugboat that is adapted to push the non-self-propelled LNG carrier.
30. The method of claim 28 , wherein:
the first vehicle comprises a non-self-propelled LNG carrier; and
the second vehicle comprises a towboat that is adapted to push the non-self-propelled LNG carrier.
31. The method of claim 18 , wherein the first vehicle and the second vehicle comprise land vehicles.
32. The method of claim 31 , wherein:
the first vehicle comprises a railroad tender car; and
the second vehicle comprises a railroad locomotive.