Comparative Energy and Exergy Analysis for the Utilization of Alternative Fuels in the Cement Kiln

The cement industry is one of the most energy and carbon-intensive industries. The energy and carbon reduction is an important issue in this industry. The present work considers the use of alternative fuels in the cement kilns. The amounts of excess air, the location of fuel and air entrance, as well as the amount of produced gas stacks, are the main design and operational variables in the kilns. Comparative assessments of alternative fuels are performed by the mass, energy, and exergy analysis of different regions in the kilns. The obtained results show that using alternative fuels reduces the amounts of excess air and the exit temperature becomes closer to the ambient temperature. The alternative fuels demonstrate lower energy and exergy loss inside the cement kiln by supplying the required energy for the clinker production. Their utilization in the current kiln reduces CO2 emissions. The results of the present work may be used for the optimal design and operation of cement kilns. This work provides an in-depth analysis of the material efficiency, main energy losses and the exergy destruction of the process.