Optimization of waste heat recovery power generation system for cement plant by combining pinch and exergy analysis methods

Waste heat recovery power generation system (WHRPGS) plays a significant role in cement plants for its contribution to the electricity supplement. Optimization of WHRPGS is very challenging when the WHRPGS is coupled with the cement producing system (CPS). In this paper, a new simplified model was proposed to characterize the integrated system (involving WHRPGS and CPS). By combining pinch analysis and exergy analysis methods, the energy process of the integrated system was studied in details. In particular, pinch analysis was used to qualitatively evaluate the improvement potentiality of the integrated system, while exergy analysis was employed to quantitatively evaluate the power generation capacity of the WHRPGS. By reducing the heat transfer across pinch points and exergy destruction of the integrated system, an optimized mode of WHRPGS was identified and the power generation capacity of it can be increased by 7.559% theoretically. The optimized WHRPGS was applied in a 2500 t·d−1 clinker production line in Northwest China. Comparing the operational results of WHRPGS in original and optimized modes for 24 h respectively, the power generation capacity of the optimized system was increased by 4.96% on average.