LOW-TEMPERATURE INTERACTIONS BETWEEN HYDROCARBONS AND NITRIC-OXIDE - AN EXPERIMENTAL-STUDY

Gas reburning is a NOx control technique that can be applied in differ ent combustion systems. In it, gas is injected into the furnace downst ream of the primary burners to form a substoichiometric zone followed by the injection of burnout air. The variables that influence the chem istry in the reducing zone (temperature between 900 and 1450 K, reburn fuel type, stoichiometry, NO concentration and residence time), which is mainly controlled by the interactions between hydrocarbon radicals and NO, have been studied in a laboratory scale flow reactor. A signi ficant NO reduction efficiency can be obtained with proper operating c onditions. The NO destruction is closely coupled to the hydrocarbon ox idation regime, which differs depending on the hydrocarbon fuel consid ered, and NO is to a significant extent converted to HCN. The concentr ation of hydrocarbons and oxygen, and the temperature are important pa rameters affecting the results obtained, whereas the inlet NO concentr ation and the residence time only have a minor effect. The practical i mplications of the present results for gas reburning are discussed. (C ) 1997 by The Combustion Institute.