Comparative analysis of the stability and structure of premixed C3H8/O2/CO2 and C3H8/O2/N2 flames for clean flexible energy production

The study compares the macrostructure and stabilization parameters of premixed oxy-propane (C3H8/O-2/CO2) and oxygen-enriched air-propane (C3H8/O-2/N-2) flames at fixed inlet velocity of 5.2 m/s and under similar conditions of oxygen fraction (OF = 21%-70%) and equivalence ratio (phi = 0.1 - 1.0) in a model dry-low-emissions (DLE) gas turbine combustor. The combustor stability maps were plotted within the phi-OF domain against background contours of constant adiabatic flame temperature (AFT), to quantify the blowout and flashback limits. It was found for both CO2- and N-2-diluted flames that the blowout and flashback limits followed constant AFT contours on the stability maps. The blowout limit of both types of flames roughly followed the same AFT contour of about similar to 1580 K, while the flashback limits followed the constant AFT contour of 2350 K. This implies that C3H8/O-2/N-2 flames blow out at leaner conditions compared to C3H8/O-2/CO2 flames. The effect of diluent type on blowout limit diminishes at higher OF; above 55% both flames blow out at phi similar to 0.2. All flames of the same AFT exhibited considerably identical shapes despite having different OF and phi. Based on that, the design and operation of future oxy-fuel turbines is recommended to be AFT-based rather than OF or phi. (C) 2020 Elsevier Ltd. All rights reserved.

Automated summary

The study compared the macrostructure and stabilization parameters of premixed oxy-propane and oxygen-enriched air-propane flames in a model dry-low-emissions gas turbine combustor. It was found that both types of flames followed constant adiabatic flame temperature contours on the stability maps, indicating that flames blow out and flashback limits are affected by AFT rather than oxygen fraction or equivalence ratio.