Deposits from gas turbine fuels are a major concern when prevaporized-premixed combustor concepts are considered for gas turbine engines. Even in conventional gas turbines, deposits are occasionally found in fuel nozzles after a long period of operation. A search was made for information regarding deposits from heated gas turbine fuels using open literature data and data generated within United Technologies Corporation. Summaries of both the data obtained from this survey and the physical and chemical mechanisms leading to the formation of fuel deposits are presented. Data obtained by Pratt and Whitney Aircraft at the Florida Research and Development Center indicate that deposits were suppressed while the fuel was vaporized by mixing with air at velocities of 6 to 13 fps (15 to 33 cm/sec) and pressures of 50 to 200 psia (3.4 to 14 atm). Data obtained at United Technologies Research Center showed that deposits can also be prevented by intermittent use of heated air. Data obtained at EXXON and at the Naval Research Laboratory show that although deposits increase with temperature, a peak is found at about 700 F (682 K). Fuel vaporization was shown to increase the deposit levels in experiments at the Air Force Aero Propulsion Laboratory.

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