Patent ID: 6468075
Filing Date: 2002-10-22
Classification: C04B,F27B,F27D

Abstract:
An apparatus for thermal processing of raw meal to produce a cement clinker in which said raw meal is preheated in a cyclone suspension heat exchanger system, through which an off-gas stream from an off gas duct (15) of a rotary kiln (16) flows; said raw meal being calcined in a precalcination stage and burned in a sintering zone of said rotary kiln (16) to cement clinker and then cooled in a downstream clinker cooler, said off-gas stream of said rotary kiln (16) and an off-gas stream of tertiary air from said clinker cooler being used to precalcinate raw meal in delivered to said off gas duct (15) by way of a raw meal stream (13) through use of a deNOx burner (19) which is supplied fuel to produce a rich fuel combustion in the rotary kiln off-gas duct (15) forming a CO-containing reduction zone (23), for the residual burnout of which at least one tertiary air substream is admitted to said rotary kiln off-gas duct (15) by way of tertiary air line (17) at a predetermined downstream juncture point, said apparatus further comprising:a pivotable vane type throttle valve (33) in said off-gas duct (15) downstream of said deNOx burner (19), downstream of the raw meal inlet (13) and upstream of the confluence of said tertiary air substream (17) and said rotary kiln off-gas, said throttle valve (33) being pivotally connected on its upstream side to said rotary kiln off-gas duct whereby the flow of rotary kiln off-gas remains laminar in all pivoted positions of said throttle valve (33).