Patent ID: 8240153

Claim:
A method for controlling the generation of turbine cooling air from air extracted from a compressor of a gas turbine, the method comprising: extracting compressed air from a low pressure stage of the compressor and from a high pressure stage of the compressor; adding in an ejector the extracted compressed air from the low pressure stage to the extracted air from the high pressure stage and discharging the compressed air from the ejector to the turbine cooling air; bypassing the ejector with a bypass portion of the extracted compressed air from the high pressure stage, wherein the bypass portion enters the turbine cooling air discharged from the ejector; adjusting the flow of the extracted compressed air from the low pressure stage to the ejector; in response to adjusting the flow of extracted compressed air from the low pressure stage, changing a set point for an actual pressure ratio that includes a pressure of the turbine cooling air; adjusting the bypass flow in response to the changed set point to cause the actual pressure ratio to approach the changed set point.