CFD Predictions and Field Measurements of NOx Emissions From LM1600 Gas Turbine During Part Load Operation

Abstract

CFD simulations of the combustion process and formation of emissions in an industrial GE LM1600 gas turbine have been performed over a range of unit loads. Two combustion models were considered here to characterize the combustion process, the chemical equilibrium model and the nonequilibrium laminar flamelet model. The flamelet model predictions of nitric oxide concentration demonstrated much closer agreement with field measurements of continuous emission monitoring systems, due to accurate modeling of the oxygen radial concentration. The predictions made with this model are within 15 percent at maximum load and considerably better at lower loads. Field measurements also showed that nitric oxide constitutes about 95 percent of the total NOx measured. Unburnt hydrocarbons and carbon monoxide emissions are significantly overpredicted, however, arguably as a result of neglecting their oxidation in the high temperature, fuel-lean environment of the turbine and exhaust stack downstream of the combustor.