Comparison of Global Ammonia Chemistry Mechanisms in Biomass Combustion and Selective Noncatalytic Reduction Process Conditions

Abstract

The success of computational fluid dynamics (CFD)-based combustion modeling is strongly dependent on several submodels which are required to close the Favre-averaged conservation equations for mass, momentum, and energy and transport equations for scalar quantities. Due to the requirement of high computer capacity, global mechanisms are frequently applied to model chemical reactions in industrial-scale CFD. The present study compares the performance of five global ammonia chemistry mechanisms in the conditions typical of the biomass combustion in fluidized beds. A special emphasis is given to the modeling of the selective noncatalytic reduction (SNCR) process. A modification of the standard k–e model is used to model turbulence, the eddy dissipation combustion model and the eddy dissipation concept are used to model turbulence–chemistry interaction, and the finite-volume method (discrete ordinates) together with the weighted sum of gray gases model are used to model radiative heat transfer. A simplified a...