Timothy S. Snyder

Comparison of Liquid Fuel/Air Mixing and NOx Emissions for a Tangential Entry Nozzle

An experimental program was conducted to develop a technique for designing a dry low NOx liquid fuel injection configuration for a tangential entry lean-premixed fuel nozzle. Calculations were performed to predict the effect of liquid fuel injection location, orifice size and spacing, and initial droplet size on the vaporized fuel/air mixture uniformity exiting the highly-swirled premixing nozzle. Combustion tests were conducted at pressures ranging from 10–18 atm, and inlet temperatures ranging from 650–730 K, for the different liquid fuel injection schemes analyzed from the mixing study. Liquid fuel injection configurations that were predicted to give the best fuel/air distribution generated the lowest levels of NOx. The calculated fuel/air uniformity was a weak function of the spatial density of liquid fuel injection sites and the method of injecting the liquid fuel. The injection location and initial droplet size have the greatest impacts on fuel/air uniformity. The analysis indicated that 40 micron diameter droplets mix adequately while larger droplets (80 micron) are centrifuged out of the main body of the flow and produce locally high fuel/air ratios. The NOx levels achieved for the best liquid fuel injection configuration approached those obtained for a well premixed gas fuel configuration using the same tangential entry nozzle.Copyright

Emission and Performance of a Lean-Premixed Gas Fuel Injection System for Aeroderivative Gas Turbine Engines

A dry-low-NOx, high-airflow-capacity fuel injection system for a lean-premixed combustor has been developed for a moderate pressure ratio (20:1) aeroderivative gas turbine engine. Engine requirements for combustor pressure drop, emissions, and operability have been met. Combustion performance was evaluated at high power conditions in a high-pressure, single-nozzle test facility which operates at full baseload conditions. Single digit NOx levels and high combustion efficiency were achieved A wide operability range with no signs of flashback, autoignition, or thermal problems was demonsuated. NOx sensitivities 10 pressure and residence time were found to be small at flame temperatures below 1850 K (2870 F). Above 1850 K some NOx sensitivity to pressure and residence Lime was observed and was associated with the increased role of the thermal NOx production mechanism at elevated flame temperatures.Copyright