ABSTRACT
This chapter presents some options for reducing the emission of pollutants. It focuses on the complex series of processes and phenomena generally grouped under acid rain. The chapter also focuses on source control via technology changes. It describes post-combustion control techniques such as selective catalytic reduction (SCR) and selective noncatalytic reduction (SNCR) by ammonia or urea injection. While SCR and SNCR control NOx emissions by treating the NOx after it has been formed in the combustion reaction, modifications to the combustion equipment or burners also significantly reduces NOx formation. Off-stoichiometric combustion (OSC), or staged combustion, combusts fuel in two or more stages. The primary flame zone is fuel-rich, and the secondary zones are fuel-lean. Staged-air burner systems divide incoming combustion air into primary and secondary paths. All fuel is injected into the throat of the burner and is combined with the primary air, which flows through the venture and burns.
