Modelling and Optimization of the NO Formation in an Industrial Glass Furnace

Abstract

The effects of combustion excess-air level, air preheating, and fuel composition on the nitric oxide emissions from an industrial glass furnace are studied through the use of a mathematical model. The mathematical model is based on the solution of the time-averaged form of the governing conservation equations for mass, momentum, energy, and chemical species. The k-ε turbulence model is employed for modelling the turbulence fluxes. The flame is modelled as a turbulent diffusion one and the chemical reactions associated with the heat release are assumed to be fast. The fluctuations of scalar properties are accounted for by use of a clipped-Gaussian probability density function. The thermal radiation, playing the dominant role in the heat-transfer process, is modelled using the discrete transfer method. Because of the high temperatures at which industrial glass furnaces operate a considerable amount of thermal NO is formed. The present work presents a model, based on a chemical kinetic approach, to predict the nitric oxide emissions from industrial glass furnaces. The Zeldovich mechanism, retaining the reverse reactions, is incorporated in the model in order to predict the instantaneous NO net formation rate from atmospheric nitrogen. The whole procedure is applied to a cross-fired regenerative furnace. A set of parametric studies is carried out, demonstrating the ability of the model to evaluate the influence of changes in operating conditions on the NO emissions.