MODELING OF COMBUSTION AND NOX EMISSIONS IN INDUSTRIAL-EQUIPMENT

The development of industrial boilers and furnaces with higher efficiencies and lower environmental impact, together with the advances in computer power promoted the development of comprehensive models to simulate fluid flow, heat transfer, combustion and pollutant formation. The present paper reviews modelling work performed at Instituto Superior Tecnico (IST) concerning the prediction of industrial combustion equipment behaviour and NO emissions. The model is based on the solution of transport equations for momentum, enthalpy, chemical species concentration and turbulent quantities. In the case of coal combustion a Lagrangian description of the particles is considered using a two-way coupling between the particle phase and continuum gas phase. In any case the NO(x) formation is considered in a post-processor routine. The models are applied to gas and oil-fired glass melting furnaces and utility boilers where NO emissions are estimated using the Zeldovich mechanism for thermal-NO. For pulverised coal combustion applications to a single burner furnace and to a multi-burner boiler are described and NO emissions are estimated using the De'Soete reaction mechanism for fuel-NO.