Reliable operation of dual-fuel gas turbines on oil demands that owner/operators protect against coking of distillate in fuel-system components. Active cooling is one solution available to users for assuring both reliable starts on liquid fuel and reliable fuel transfers from gas to oil.
Recall that stagnant fuel in supply lines not protected against heat radiated from the gas-turbine casing transitions to solid coke over time. In earlier stages of the coking process a tar-like substance is created that fouls check valves, coats fuel-nozzle passages, and builds up on the inside surface of oil piping. Case in point: Key components of liquid-fuel systems on many dual-fuel 7FA gas turbines are located in a 500F environment, double the nominal 250F temperature at which coking of distillate begins.
JASC, Tempe, Ariz, has been at the forefront of industry efforts to improve the reliability of liquid fuel systems for well over a decade. The company’s subject-matter expert, Schuyler McElrath, told the editors, “Active cooling of the fuel supply system has been a fundamental component of our technology and has demonstrated the ability to improve reliability.”