Abatement of NOx emissions from pulse detonation combustion

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With the aim of developing highly efficient, load-flexible and low-emission gas turbines utilizing sustainable energy carriers produced via power-to-gas (PtG) or power-to-liquid (PtL) processes, significant scientific efforts on implementing pressure gain combustion (PGC) are ongoing. Pulse detonation combustion (PDC) represents one possible concept for practical implementation. Here, investigations on the emission behavior play a decisive role. Due to very high temperatures and pressures within detonation waves, the consideration of NOx emissions is especially important. The present research project is a continuation project based on the findings of the previous project on the quantification of NOx emissions from a hydrogen-powered PDC and the application of primary NOx reduction measures. NOx concentrations measured in the exhaust gas were thereby reduced by at least one order of magnitude using the conventional reduction measures of lean combustion and exhaust gas recirculation (emulated by nitrogen dilution). A consideration of the influence of these reduction measures on the detonability of resulting combustion mixtures on the basis of the characteristic detonation cell size showed that an improvement of the plant-specific capability for detonation initiation (i.e. the limits of a successful deflagration-to-detonation transition, DDT) holds further potential for NOx reduction. The first goal of this project is therefore to enable further reduction of NOx emissions by suitable experimental adaptations such as the extension of the DDT section and/or a stratification of the fuel distribution within the combustion chamber, with the aim of meeting the legal emissions limits during operation with hydrogen. The second aspect of the present research project is the extension of the investigations to the operation with hydrocarbons, whereby ethylene serves as a surrogate for higher hydrocarbons. Their use means a completely different starting position for the reaction kinetic processes and thus has a significant influence on the emissions of NOx as well as of carbon monoxide (CO) and unburnt hydrocarbons (UHC). The interaction with these additionally formed pollutants is still largely unexplored for detonation combustion. This includes both the effect of operating conditions as well as the reduction of pollutant emissions through appropriate primary measures. In addition to the experimental investigations, numerical and kinetic analyses provide an in-depth understanding of underlying physico-chemical processes of pollutant formation in PDC and thus lay the foundation for the development of low emission detonation-based combustion systems.