Flame Characteristics and Emissions in Flameless Combustion Under Gas Turbine Relevant Conditions

• Published in: Journal of propulsion and power 2011-09, Vol.27 (5), p.970-980
• Main Authors: Sadanandan, R, Lückerath, R, Meier, W, Wahl, C
• Format: Article
• Language: English
• Subjects: Admixtures; Combustion; Delay; Gas turbines; Imaging; Natural gas; Premixing; Reduction
• ISSN: 0748-4658; 1533-3876
• DOI: 10.2514/1.50302

The combustion behavior of natural gas flames with H2H2 as an admixture is investigated in an optically accessible combustor operating under gas turbine relevant conditions. OH*OH* chemiluminescence imaging and planar laser-induced fluorescence measurements of OH were performed along with exhaust gas analysis to investigate the influence of various parameters like mixture composition, degree of premixing, and velocities on the pollutant emissions. The results show that the degree of premixing along with the recirculation rate of the burned gases plays an important role in NOxNOx and CO emissions. Compared with pure natural gas fired flames, the ones with H2H2 admixture burned closer to the burner due to an increased reactivity. Under such conditions, a low emissions operating range can be achieved either by increasing the jet velocities or by reducing the degree of premixing. Both methods favor NOxNOx reduction due to the suppression of local peak flame temperatures. The optimum combination of degree of premixing and jet velocity should lead to a recirculation and mixing rate such that the resulting ignition delay is long enough to promote mixing of the fresh fuel/air with the burned gases before the flame reactions but short enough to ensure a stable operation of the burner. At the same time, combustor residence times should be short in order to reduce the thermal-NO formation but long enough to enable complete combustion. [PUBLISHER ABSTRACT]