Modeling of the Thermal Efficiency of a Whole Cement Clinker Calcination System and Its Application on a 5000 MT/D Production Line

This paper proposes that the scope of research should be extended to the whole clinker calcination system from its single device or specific process (i.e., its functional subunits) as conventionally conducted. Mass/heat flow and effective heat were first analyzed to obtain the thermal efficiencies of its subunits (φⁱ); a thermal efficiency model of the whole system φ^QY was thus established by correlating the relationship between φⁱ and φ^QY. The thermal efficiency model of the whole system showed that φⁱ had a positive linear correlation with φ^QY; it was found that the thermal efficiency of the decomposition and clinker calcination unit (φ^DC) had the greatest weight on φ^QY, where a 1% increase in φ^DC led to a 1.73% increase in φ^QY—improving φ^DC was shown to be the most effective way to improve φ^QY. In this paper, the developed thermal efficiency model was applied to one 5000 MT/D production line. It was found that its φ^QY was only 61.70%—about 2.35% lower than a representative line; such decrease was caused by its low φ^DC and φ^P which, as disclosed by model, were derived from the low decomposition rate of calcium carbonate in preheated meal put into a calciner and the high excess air coefficient of secondary air. Controlled parameter optimization of this 5000 MT/D production line was then carried out. As a result, the φ^DC and φ^P of the production line were increased from 30.03% and 64.61% to 30.69% and 65.69%, respectively; the φ^QY increased from 61.70% to 62.55%; the clinker output of the production line increased from 5799 MT/D to 5968 MT/D; the heat consumption of clinker was reduced from 3286.98 kJ/kg·cl to 3252.41 kJ/kg·cl.