Patent ID: 6544032
Filing Date: 2003-04-08
Classification: C04B

Abstract:
A method of heat treatment of fine-grained material for production of cement clinker from cement raw material, comprised of the following steps of:preheating the material in a preheating zone by means of hot gases; further heating the preheated material and at least largely calcinating the preheated material in a calcination zone through which hot exhaust gases from a combustion zone flow and which is supplied with additional fuel; burning the calcined material in a combustion zone and cooling the burnt material in a cooling zone, exhaust air from the cooling zone being introduced as combustion air into the calcination zone; operating at least an inlet region to the combustion zone under reducing conditions by addition of additional fuel to reduce nitrogen oxide content of the exhaust gas from the combustion zone; introducing ammonia-containing additives, in order further to reduce the nitrogen oxide content, into the gas stream of the calcination zone which is produced after introduction of exhaust air from the cooling zone into the exhaust gas from the combustion zone and is supplied with additional fuel; wherein at least the predominant proportion of the ammonia-containing additives is only added in a region of the calcination zone in which the secondary combustion of the combustion products which are formed in a section which is operated under reducing conditions but are not completely reacted out is largely concluded.