Abstract
ABSTRACT A model natural gas–fired gas-turbine combustor is utilized to evaluate active optimization strategies. Sensors for exhaust species and reaction zone chemiluminescence are utilized with an adaptive fuel injection strategy in a closed-loop feedback control system. The feedback sensors consist of (1) traditional extractive probe-based exhaust measurements of CO and NOx emissions and (2) chemiluminescence to provide very fast, yet accurate, indicators of performance. A direction-set algorithm is utilized to search for the region of optimal performance. The objectives of the study are to assess (1) the viability of controlling the spatial distribution for performance control; (2) the use of flame chemiluminescence as a fast, inferential emissions sensor for faster feedback; and (3) the robustness of the adaptive control strategy over the entire operability range and under a simulated perturbation mode. For the current study, a simulated injector perturbation scenario (partial fuel-jet blockage) is utilized to examine the robustness of the optimization strategies. The results obtained illustrate the relative correlation of the different sensor strategies with system performance and the ability of the closed-loop control to maintain combustion performance in light of a simulated hardware perturbation.
Highlights
Due to increasingly stringent emissions regulations for industrial, stationary combustion sources, low-emissions technologies are relying more and more on lean, well-mixed, or premixed strategies
This study investigates the applicability of adaptive fuel injection to stationary gas turbines in relation to these challenges and over several operational scenarios
The average COÃ2 signal was found to correlate with the exhaust nitrogen oxides (NOx) concentration, and the percent fluctuating COÃ2 signal to the exhaust carbon monoxide (CO) emissions (Figure 4)
Summary
Due to increasingly stringent emissions regulations for industrial, stationary combustion sources, low-emissions technologies are relying more and more on lean, well-mixed, or premixed strategies. These strategies, proficient at reducing NOx emissions, suffer from reduced stability or decreased system efficiency under operating conditions that are often desirable for low emissions; as a result, highperformance operation can present operational and safety challenges. Active control of gas turbines has been studied using dynamic control of the fuel injection to offset combustion instabilities (e.g., Lee et al, 1998; Neumeier and Zinn, 1996). The research addressed in this paper investigates this latter strategy, that is, to minimize emissions by actively controlling the spatial fuel and air mixedness such that high performance is achieved despite changes in load (equivalence ratio) or hardware degradation
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