Assessment of RQL Trapped Vortex Combustor for Stationary Gas Turbines

Abstract

This paper describes the evaluation of an alternative combustion approach to achieve low emissions for a wide range of fuel-types. This approach combines the potential advantages of a staged Rich-burn, Quick-mix, Lean-burn (RQL) combustor with the revolutionary Trapped Vortex Combustor (TVC) concept. Although RQL combustors have been proposed for low-BTU fuels, this paper considers the application of an RQL combustor for high-BTU natural gas applications. This paper will describe the RQL/TVC concept and experimental results conducted at 10 atmospheres (1013 kPa or 147 psia) and an inlet-air temperature of 644K (700°F). The results from a simple network reactor model using detailed kinetics are compared to the experimental observations. Neglecting mixing limitations, the simplified model suggests that NOx and CO performance below 10 parts-per-million could be achieved in an RQL approach. The CO levels predicted by the model are reasonably close to the experimental results over a wide range of operating conditions. The predicted NOx levels are reasonably close for some operating conditions, however, as the rich-stage equivalence ratio increases, the discrepancy between the experiment and the model increases. Mixing limitations are critical in any RQL combustor, and the mixing limitations for this RQL/TVC design are discussed.