MODELING OF NOX REBURNING IN A PILOT-SCALE FURNACE USING DETAILED REACTION-KINETICS

A Zone Model has been developed for the prediction of NO reduction by ''reburning'' in turbulent diffusion flames. The computations of fluid dynamics are decoupled from those of detailed combustion chemistry in cluding those of the nitrogen species. The calculations begin with the computations of the stream function, heat release, temperature, and m ajor species concentration distributions using a commercial CFD code a nd simple, one or two step chemistry. The modeled space is then subdiv ided into volume elements (zones) bounded by streamlines and some axia l coordinate. The sizes of these zones are much larger than those of a computational grid so that it is practicable to use detailed chemistr y for the calculation of progress of reaction within such a zone. In t he experimental investigation natural gas with and without additive NH 3 was used as ''reburn'' fuel. It was injected axially into the NO bea ring combustion products of a 335 kW natural gas-air flame to obtain a parabolic flow which can be modeled more easily. Detailed in-flame me asurements permitted critical tests of the prediction method by the co mparison of experimental and calculated data.