Thermodynamics of Modern Low-Emission (Low-NO_X) Processes in the Combustion of Hydrocarbon Fuels

This paper focuses on the results achieved through the addition of previously unaccounted for processes to existing calculation procedures relevant to combustion units as a whole and low-emission boiler furnaces in particular. It concerns the processes accompanying the use of NO_x reduction facilities. Numerical simulations have been performed with respect to the chemical reactions of natural gas and/or methane–air mixtures in the recirculation of flue gases (combustion products). It is concluded that measures taken to reduce NO_x emissions cause soot formation due to the fact that they involve the conversion of natural gas with steam, carbon dioxide or a combination of the two. The dependence of the thermodynamic equilibrium soot concentration on both the controlling temperature and concentration process conditions have been determined, based on the results of numerical simulations.