Abstract: Methods and systems for a dry low NOx gas turbine engine system include a gas turbine engine including at least one dry low NOx combustor. The combustor includes a plurality of injection points wherein at least some of the injection points are configured to inject a fuel into the combustor at a plurality of different locations. The system includes a water source coupled to the combustor and operable to inject water into others of the plurality of injection points. The system also includes a control system that includes a sensor configured to measure an exhaust gas concentration of the turbine, a processor programmed to receive a signal indicative of the turbine exhaust gas concentration, and to automatically control the water injection using the received exhaust gas concentration signal. Such systems in use together can mitigate visible emissions from the exhaust stack.

Abstract: A method for combustion in a combustor in a gas turbine including: fueling the center fuel nozzle with a fuel-rich mixture of gaseous fuel and air and fueling the outer fuel nozzles with a fuel-lean mixture of fuel and air; igniting the fuel-rich mixture injected by the center fuel nozzle while the fuel-lean mixture injected by the outer combustors is insufficient to sustain ignition; stabilizing a flame on the center fuel nozzle using the bluff body and while the outer fuel nozzles inject the fuel-lean mixture; staging fuel to the outer nozzles by increasing a fuel ratio of the fuel-lean mixture, and after the outer nozzles sustain ignition, reducing fuel applied to the center nozzle.

Abstract: A single stage combustor for a gas turbine having an annular array of outer fuel nozzles arranged about a center axis of the combustor; a center fuel nozzle aligned with the center axis, wherein the center fuel nozzle is substantially smaller than each of the outer fuel nozzles, wherein the combustor includes a pre-mix operating mode in which the center nozzle receives a fuel rich air-fuel mixture.