Method for Switching over a Gas Turbine Burner Operation from Liquid to Gas Fuel and Vice-Versa

The invention refers to a method for switching over a gas turbine burner operation from liquid fuel (21) to gas fuel (22, 23) and vice-versa. The burner (1) comprises two conical shells (2) defining a substantially conical swirl chamber (3) provided with tangential slots (5) for feeding air (20) and nozzles (6) for feeding a premix gas fuel (22) therein, nozzles (8) for injecting a pilot gas fuel (23) and a lance (7) disposed centrally in the conical chamber (3) and arranged to inject a liquid fuel (21) therein. While the liquid fuel (21) and the premix gas fuel (22) are regulated to switch over from liquid fuel to gas fuel operation or vice-versa, the pilot gas fuel (23) is controlled at a substantially constant flow rate.