Simulation of pollutant emissions from a gas-turbine combustor

In the present study, an emission model using a detailed chemical kinetic scheme is used to provide the trends of formation and/or consumption of nitrogen oxides (NO_x), carbon monoxide (CO), and unburned hydrocarbons (UHCs) in various zones of a conventional gas-turbine combustor. This model consists of a number of chemical reactors in series and/or in parallel that simulate various regions of the combustor. The success of this type of approach relies on the proper selection of the flow model and the reactor arrangement, in addition to the inclusion of means to account for spray evaporation and mixing in the combustion zone. The computational results show that NO_x emissions are higher for longer residence times in the combustor, whereas CO and UHC are, on the contrary, lower. Because these last two are normal intermediates in hydrocarbon combustion, the problem is one of consumption rather than production. Their emissions increase with lower residence times, which reduces their chances to be oxidized.