AIR INJECTION FOR NITROGEN OXIDE REDUCTION AND IMPROVED PRODUCT QUALITY

摘要

A calcining system (10) is operated in a substoichiometric mode for reducingnitrogen oxide generation and removing sulfur from materials (26) to beprocessed by creating an oxygen deficient atmosphere. The calcining system(10) includes a rotary kiln (14) rotating on a slightly inclined horizontalaxis. The rotary kiln (14) has a feed end (22) introducing material (26) to beprocessed and a discharge end (24). A preheating/precalcining device (12) ispositioned adjacent the feed end (22) such that the material (26) passesthrough the device (12) prior to entering the rotary kiln (14). A stationaryhood (16) surrounds the discharge end (24). A burner (18) is supported by thestationary hood (16). The burner (18) introduces combustible fuel (38) andcombustion air (40) into the rotary kiln (14) through the discharge end (24)and operates in a substoichiometric mode. At least on air nozzle (44) islocated along the length of the rotary kiln (14). The air nozzle (44) injectscombustion air (40) into the rotary kiln (14). The combustion air (40C)introduced by the air nozzle (44) completely combusts the combustible fuel(38) introduced by the burner (18) before the combustible fuel (38) exits thefeed end (24).