Method for starting a gas turbine plant with an air accumulator

Claim 1

In the method for starting-up a gas turbine system by means of compressed air delivered from an air-storage chamber, and wherein said turbine system is comprised of a high-pressure turbine and a low-pressure turbine operating on a common shaft, a high-pressure combustion chamber preceding said high-pressure turbine, a low-pressure combustion chamber preceding said low-pressure turbine in the air flow path, and a connection from said air-storage chamber to said high-pressure combustion chamber, and wherein a rotary load such as an electrical generator is connectible to said turbine shaft through coupling means, the improvement characterized by the following steps: (a) feeding compressed air from said storage chamber through said turbine system to accelerate the same to normal operating speed, (b) igniting said high-pressure combustion chamber during the acceleration of said turbine system and controlling fuel flow thereto such as to maintain the air admission temperature to said high-pressure turbine at a minimum value, (c) coupling the rotary load to said turbine shaft, (d) igniting said low-pressure combustion chamber, (e) increasing the pressure at the high-pressure combustion chamber up to the full operating pressure thereby raising the quantity of air flow through said high- and low-pressure turbines to an amount greater than is normally maintained during the operating period of the turbine system, (f) increasing the admission temperature of the air at said low-pressure turbine until the full output of the turbine has been reached, and (g) increasing the admission temperature of the air at said high-pressure turbine linearly from said initially minimum value to the full operating temperature while simultaneously decreasing the flow rate of said air, the increasing increase in admission temperature of the air at said low-pressure turbine being made simultaneously with the increase in admission temperature of the air at said high-pressure turbine whereby the output of the turbine system will remain constant and the rate of air flow through the turbine system is reduced to its normal value.