Enhancing Sustainability and Energy Savings in Cement Production via Waste Heat Recovery

Cement production is one of the most energy-efficient industries. During the clinker formation and cooling processes, excess heat is lost to the atmosphere. For this reason, using waste heat to generate useful energy is considered the most promising approach to sustainable cement production. In this study, advanced modeling tools, Aspen Plus and Aspen Energy Analysis, are employed to identify the potential for enhancing energy efficiency and sustainability in a cement plant with an annual output of 1 million metric tons. The analysis reveals two primary sources of recoverable waste heat: 29.7 MW from the preheater flue gas and 30.82 MW from the cooler gas stream, totaling 60.52 MW. Two case studies are examined to evaluate the feasibility and benefits of different heat recovery strategies. In the first case, excess heat from the preheater flue gas is utilized for raw material dehydration and power generation through a waste heat recovery unit (WHRU), producing 5.026 MW, while the cooler gas stream is used in another WHRU for an additional 7.901 MW of power. In the second case, power generation from excess heat and steam production for an amine-based CO2 absorption unit were considered. Our research underscores the substantial opportunities for energy savings and environmental improvements in the cement industry through waste heat recovery, offering viable solutions for more sustainable and efficient cement production processes.