Liquid petroleum gas flame in a double-swirl gas turbine model combustor: Lean blow-out, pollutant, preheating

Abstract

In this paper, lean blow-out limits in a double swirl GT model combustor were investigated experimentally for liquid petroleum gas fuel. The lean blow-out curve was extracted for different combustor configurations. While burner could operate reasonably under ultra-lean conditions, two different sets of operating conditions, one with a low flow rate and another one with high flow rate, are identified and studied in terms of lean blow-out and pollutant. Results showed that while the flame structure was similar in both cases, the chamber responses to geometrical changes and also preheating are minimal at the low flow rate. That means confinement and injector type have desirable effects on stability borders but not for the low flow rate. The channeled injector shifted down the lean blow-out limit around 28% at high flow rate. Measurements on the combustor exhaust gas composition and temperature indicate a region with relatively complete combustion and reasonable temperature and a very low level of exhaust NOx pollutants (i. e., below 10 ppm) at about 25-50% above the lean blow-out. In this operating envelope, a burner power increment led to a higher exhaust average temperature and combustion efficiency, while NOx formation decreased. Preheating the inlet air up to 100?C results in an improvement in burner stability in about 10%, but NOx production intensifies more than three times. Results indicate that the lean blow-out limit is con-figured more by the burner design and aerodynamic aspects rather than the fuel type.