Assessment of Rich-Burn, Quick-Mix, Lean-Burn 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 atm (1013 kPa or 147 psia) and an inlet-air temperature of 644 K (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.

Optical diagnostics of fuel–air mixing and vortex formation in a cavity combustor

“…They suggested the presence of a dual vortex structure in providing improved stability and mixing. This was also reported by Straub et al [7] for a stationary gas turbine engine combustor.…”

Fundamentals and Applications of Modern Flow Control

“…Earlier successful passive strategies developed for liquid rocket motor combustion instability control (e.g., Cox and Marble, 1953;Crocco et al, 1960;Culick and Yang, 1995;Harrje and Reardon, 1972;Yang et al, 1990) fall in this arena. For example, researchers (e.g., Straub et al, 2005) have been exploring combustion systems that can meet these goals without requiring major hardwire redesign. Recent effort has also focused on developing and demonstrating alternate combustion systems that can achieve low emission over a wide range of fuel types without requiring an ACS.…”

Impact of interaction between cavity flow and mainstream on the performance of a model trapped vortex combustor

“…A model combustor that combines TVC with rich-burn, quick-mix, lean-burn (RQL) concept was reported by Straub et al. 13,14 A large discrepancy of NOx emission between the experiment and the predicted results, which attribute to incomplete mixing between cavity and mainstream flow, has been observed. Bucher et al.…”