Caption title. At head of title: Project summary. Distributed to depository libraries in microfiche. "May 1985." "EPA/600-S7-85-012."

A study was initiated to investigate in-furnace NO[subscript x]/SO[subscript x] reduction techniques through the combined use of reburning and limestone injection. Reburning is a multistage combustion modification technique in which fuel is added downstream of the main firing zone to produce a fuel-rich zone where NO from the main firing zone is reduced. BUrnout air is added farther downstream to provide for complete burnout of the reburning fuel. Sorbent injection involves injection, into the furnace, of calcium-based materials onto which SOb2s can be absorbed. Tests have been carried out at bench scale (20.5 kW) to investigate the impact of process variables on the effectiveness of the combined technology. Under the best conditions, up to 80% NO[subscript x] reduction and 60% removal of SO[subscript x] at a calcium/sulfur ratio of 2 have been achieved. The impact of each variable in each zone was investigated independently. The dominant parameters were found to be the reburning condition and the primary NO level. The time, temperature, and stoichiometric requirements of the reburning zone influenced NO[subscript x] reduction efficiency in a manner consistent with a kinetically controlled process; i.e., higher temperatures and longer residence times at an optimum stoichiometry of 0.9 were favorable. SO[subscript x] reduction was most influenced by the location of injection of the sorbent; in particular, injection with the burnout air was optimum.