Patent ID: 7377773

Claim:
A method of reducing NOx emissions in a rotary preheater limestone kiln having a feed zone, a preheat zone, a calcining zone and a cooling and discharge zone, the method comprising the steps of: feeding a supply of limestone to the feed zone; moving the limestone through the preheat zone having a preheat temperature range, to an upper end of the calcining zone where the limestone is heated to a temperature and for a time sufficient to convert the limestone to quicklime; introducing a source of ammonia or an ammonia precursor at a point where the temperature in the kiln is within an optimum temperature range to obtain maximum NO x reduction with minimum NH 3 slip; injecting turbulent air at preselected point or points downstream of the preheat zone to reduce stratification of kiln gases and improve the energy efficiency of the kiln; passing the calcined limestone from the calcining zone to the cooling and discharge zone and discharging the resulting quicklime from the kiln.