Exergetic analysis and pollutants emission from a rotary kiln system in a major cement manufacturing plant

Abstract

The exergy analysis and air pollutants emission estimation from the kiln system of a major cement manufacturing plant located in Nigeria were conducted with a view to improve the level of performance of the production unit and minimize environmental effects. Material balance and exergy analysis were carried out on the system to determine the exergetic efficiency and exergy destruction rate. Pollutants emission was estimated using bottom-up emission factor approach. The physical and chemical exergy output obtained were 9.07×107 and 1.46×08 kJ/h, respectively. The exergy efficiency of the kiln system was 27.35%. The measure of entropy generation (6.53×108 kJ/h) represented a huge potential for energy savings for the unit. CO2 emission represented about 99.04% of the total criteria air pollutants emission from the kiln and an estimate of 0.90 tonnes of CO2/tonne of clinker produced was obtained. To improve the exergy efficiency and reduce pollutants emission from the kiln system, possible heat recovery options and CO2 mitigation approaches were suggested.