Patent ID: 8371102

Claim:
A system for controlling the uniformity of combustion over a range of operating conditions in a combustor that comprises a plurality of fuel nozzles that each spray a flow of fuel into the combustor, wherein each nozzle influences a state of combustion in a combustor segment, and wherein the combustor emits exhaust, the system comprising: a plurality of optical sensors, each sensor comprising an optical probe that is located at least in part in a fuel nozzle and collects naturally occurring optical radiation emanating from a segment of the combustor within which combustion is primarily influenced by one or a small set of nozzles, and at least one transducer that receives the radiation collected by one or more of the probes, compares the intensity of collected radiation in a plurality of spectral pass-bands that are indicative of a fuel/air ratio in the combustor segments, and produces sensor output signals that are a function of the relative intensity observed in a plurality of pass-bands, where that function is independent of the overall intensity of the radiation and has a monotonic dependence on fuel air ratio within an operating range about a nominal set point; a control system that receives the sensor output signals and in response controls the fuel flow to the fuel nozzles to achieve a predetermined pattern of sensor output signals that is indicative of a predetermined state of combustion; wherein the control system causes a cyclical modulation of fuel flow to each fuel nozzle, monitors the resulting change of the optical radiation received by each sensor, and then determines the partial derivative of each sensor signal with respect to fuel flow through each nozzle; and wherein the control system causes an adjustment of the fuel flow to each of the nozzles so as to reduce variations of sensor output signals among the combustor segments.