Patent ID: 8578717
Filing Date: 2013-11-12
Classification: F02C,F05D

Abstract:
1. A method for avoiding malfunctions during load reductions in a double shaft gas turbine of the type comprising at least one compressor, capable of compressing the air introduced into it through an inlet duct, at least one combustor, in which said compressed air is mixed and combusted with a gaseous fuel coming from a feeding duct, and at least one turbine, capable of transforming the energy of the combusted gas coming from said combustor into work energy which can be exploited for activating one or more operating machines, wherein said combustor is equipped with a plurality of burners and wherein said compressor is equipped with a plurality of adjustable stator vanes, one or more anti-surge valves and one or more overboard bleeds, the method comprising performing the following steps in sequence: (a) reducing a flow of the gaseous fuel entering said combustor to a predefined minimum value, if an increase is observed in the rotation regime of said turbine above a predefined maximum value and a total reduction in the load; (b) modifying the angulation of said plurality of adjustable stator vanes in order to reduce the speed rate of said compressor; (c) opening said one or more anti-surge valves and said one or more overboard bleeds in order to reduce an air flow at an inlet of said combustor; and (d) supplying a maximum quantity possible of the gaseous fuel to one or more burners in order to cover an overall demand for the gaseous fuel of said turbine and to avoid a flame loss if said turbine is operating in premixed flame mode.