A Comparison of Flowfields and Emmissions of High-Swirl Injectors and Low-Swirl Injectors for Lean Premixed Gas Turbines

A Comparison of Flowfields and Emmissions of High-Swirl Injectors and Low-Swirl Injectors for Lean Premixed Gas Turbines

TitleA Comparison of Flowfields and Emmissions of High-Swirl Injectors and Low-Swirl Injectors for Lean Premixed Gas Turbines
Publication TypeJournal Article
Year of Publication2005
AuthorsMatthew R Johnson, David Littlejohn, Wazeer A Nazeer, Kenneth O Smith, Robert K Cheng
JournalProceddings of the Combustion Institute
Volume30
2867
Issue2
Pagination2867-2874
Date Published01/2005
Keywordsemissions, Gas turbines, Lean premixed, NOx, swirl
Abstract

A new approach for low emission gas turbines was investigated by modifying a typical production high-swirl injector (HSI) for gas turbine combustors to operate in a novel low-swirl mode (LSI). This LSI (S = 0.5) was configured in the laboratory and investigated by particle image velocimetry at firing rates of 9–87 kW (1 < U0 < 10 m/s). It was also tested at simulated gas turbine conditions of 0.08–2.2 MW (20 < U0 < 50 m/s) at elevated combustion inlet temperatures (230 < T0 < 430 °C) and pressures (6 < P0 < 15 atm). The results were compared with those obtained with a HSI (S = 0.73). The PIV results show that the flowfields of the LSI are devoid of a large dominant recirculation zone. This is fundamentally different than the strong and large recirculation regions that dominate flowfields of the HSI. Under simulated engine conditions, the LSI has the same operating range as the HSI. Its NOx emissions were about 60% lower than the HSI, and its CO emissions were comparable. The lack of a strong recirculation zone and the shorter residence time within the LSI may provide an explanation for the NOx reduction. These results demonstrate that the LSI is a promising solution for attaining an ultra-low emissions target of <5 ppm NOx (15% O2) in gas turbines.

DOI10.1016/j.proci.2004.07.040