Air injection for nitrogen oxide reduction and improved product quality

摘要

A calcining system is operated in a substoichiometric mode for reducing nitrogen oxide generation and removing sulfur from materials to be processed by creating an oxygen deficient atmosphere. The calcining system includes a rotary kiln rotating on a slightly inclined horizontal axis. The rotary kiln has a feed end introducing material to be processed and a discharge end. A preheating/precalcining device is positioned adjacent the feed end such that the material passes through the device prior to entering the rotary kiln. A stationary hood surrounds the discharge end. A burner is supported by the stationary hood. The burner introduces combustible fuel and combustion air into the rotary kiln through the discharge end and operates in a substoichiometric mode. At least one air nozzle is located along the length of the rotary kiln. The air nozzle injects combustion air into the rotary kiln. The combustion air introduced by the air nozzle completely combusts the combustible fuel introduced by the burner before the combustible fuel exits the feed end.