Introduction

This chapter presented an overview of current gas-turbine combustion technologies and the associated challenges. The need to reduce NOx emissions drove gas-turbine manufacturers to abandon the conventional non-premixed combustor technologies and switch to the current lean-premixed (LPM) ones. Non-premixed combustors have been used traditionally because of the superior flame stability they enjoy. LPM combustors, on the other hand, are prone to static instabilities (blowout and flashback), which limits the operability window significantly. They are also prone to dynamic (acoustic) instabilities. Some premixer technologies are presented, such as DACRS and micromixers, which are responsible for premixing fuel with air to create the LPM flame. Carbon capture technologies are discussed, including pre-, post-, and oxy-combustion technologies. Focus is made on oxy-combustion of hydrocarbons for carbon capture and the associated challenges for the implementation of this technology with minimum hardware changes. Stratification, i.e., fuel and/or air staging is also presented as a means of addressing most of the challenges of LPM air–fuel systems as well as premixed oxy-fuel ones. The stratification concept intentionally seeks heterogenization of the overall equivalence ratio, which is achieved through staging or splitting of reactant flow. Stratified combustion is one of the attention-seeking contemporary technologies, employed in state-of-the-art gas turbines to achieve ultra-low emissions, enhanced stability, and superior turndown (ratio of maximum to minimum loads). Finally, the fuel flexibility approach for improved combustion characteristics at reduced emissions is discussed considering hydrogen-rich and syngas combustion.