Sarcheshmeh lime rotary kiln in the south of Iran consumes a lot of thermal energy compared with other rotary kilns. As a result, Sarcheshmeh lime kiln is being investigated for the potential to improve energy consumption. Experimental data and CFD simulation are both used in this paper. The numerical simulation has been performed for three modes to investigate the problems and solutions of energy consumption in the lime kiln: design mode, operation mode, and effect of operating condition changes. In the last mode, five parameters including the percentage of excess air, the ratio of primary to secondary air flow, primary air flow, moisture, and particle size of limestone are studied and discussed. To consider different factors of lime kiln operation, the numerical simulation takes into account all three major phenomena of fuel combustion in the burner, limestone calcination, and particle movement. Operating conditions measurements with mass and energy balances show that there is insufficient suction air from the secondary air inlet to the burner head. This is due to multiple leaks from the kiln’s initial length part, resulting in incomplete combustion and fuel waste eventually. According to CFD simulation, lowering the size of the intake limestone particles enhances the calciantion of limestone. Also, if quicklime’s maximum temperature is limited, a higher ratio of primary to secondary airflow can be used, in which case the degree of conversion of limestone to quicklime at the kiln exit remains constant

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