Novel methods of providing fuels to a gas-to-liquids facility are disclosed.
A gas-to-liquids facility typically operates in a remote location and therefore
must supply its own energy needs. These facilities are often sustained by fuels
having different heating values, and for smooth operation while transitioning from
one fuel to another, (such as during startup, shut down, and emergencies) the Wobble
Indices of the two fuels cannot greatly vary from one another. According to embodiments
of the present invention, the Wobble Index of either or both of the fuels is adjusted
such that their ratio is less than or equal to about 3. The fuel having the higher
Wobble Index may be natural gas, and materials such as nitrogen, carbon dioxide
and flue gas may be added to lower its Wobble Index. The fuel having the lower
Wobble Index may be the tail gas of a Fischer-Tropsch synthesis, and materials
such as methane, ethane, LPG, or natural gas may be added to raise its Wobble Index.
Alternatively, carbon dioxide may be removed from the tail gas to raise its Wobble Index.
