Stationary combustion: The environmental leitmotiv

Abstract

Combustion and pollutant formation are inseparable processes. Because of the central role of direct fossil fuel utilization in the provision of heat and power for the foreseeable future, major efforts are being made to ameliorate the environmental effects. The most cost-effective way of reducing pollutant emission is the modification of the combustion process. Combustion scientists and engineers have developed new clean combustion technologies based on the better understanding of the physicalchemical bases of NOx formation and destruction in flames, the capture of SO2 by additive sorbent or ion-exchangeable alkali compounds, the formation and destruction of PACs, and the formation of fine inorganic aerosols in high temperature combustion processes. New information has become available on the mechanism of coal combustion, on the effect of fragmentation of coal and char particles upon the rates of heterogeneous reactions of carbonaceous solids and on the development of the fly ash size distribution. It is of interest to note that while it is combustion chemistry that provides guidance for the development of combustion processes with reduced pollution emission, the realization of the required concentration-temperature history of the fuel in furnaces, boilers and combustors represents a challenge to combustion physics, notably fluid dynamics and heat transfer.