Thermal performance combined with cooling system parameters study for a roller kiln based on energy-exergy analysis

Abstract

Roller kilns, characterized as high energy consumption equipment, are widely used in the firing process of ceramic tiles. To evaluate the thermal performance of a roller kiln, a detailed energy and exergy analysis is carried out employing the operating values from a typical ceramic factory. In this study, parametric studies are performed that examine the impacts of the roller kiln’s cooling system on thermal performance, fuel-saving, cost-saving, and environmental influence. The results show that the targeted energy only accounts for 13.4% and 9.7% of the total energy and exergy inputs, indicating the poor efficiency of the roller kiln. This research also identifies that the exergy destruction is the largest cause of the exergy loss in the system, accounting for 85.1% of the total exergy input—of which 50.9% is due to heat and mass transfer, and 37.9% is caused by fuel combustion. Based on the parametric studies, it has been found that with every 1% increase in cooling air mass flow, the energy and the exergy efficiencies of the kiln increase by 0.06% and 0.04%; with every 1% increase in cooling gas temperature, the energy and the exergy efficiencies of the kiln drop by 0.09% and 0.07%; with every 1% increase in cooling gas residence time, the energy and the exergy efficiencies of the kiln increase by 0.16% and 0.12%. Furthermore, results show that the cooling air residence time has the main impact on the cost-saving and carbon dioxide emission reduction, followed by cooling air mass and cooling air temperature.