Numerical Modeling of Selective Non Catalytic Reduction DeNOx Process

Paper in proceeding, 2013

The introduction of strongly non-linear chemistry effects in numerical simulation of Selective Non Catalytic Reduction (SNCR) DeNOx is addressed. In these systems, NOx in flue gas is reduced by injecting either ammonia or urea. To predict the NOx reduction, turbulent mixing and its interaction with chemistry occurring at small scales unresolved by the mesh must be modeled. In addition, detailed reaction mechanisms for SNCR are large and contain numerous species and elementary reactions. These mechanisms need to be simplified for their subsequent introduction in flow simulations. In this paper, two different methods for reducing the cost of chemistry that relies on automated optimization tools are discussed. The first one is based on the tabulation of the detailed chemistry response from canonical problems, using automatically defined progress variables. In the second one, a large sample of detailed chemistry solution points is processed by an iterative optimization procedure, leading to a reduced two-step chemistry reproducing the targeted detailed chemistry solutions.