Exergetic, exergoeconomic, and exergoenvironmental analyses of an existing industrial olefin plant

Abstract

Light olefins production via thermal cracking of hydrocarbons is a process with the highest value of energy consumption in the petrochemical industry. Therefore, the study of the process from three points of view, i.e., thermodynamic, economic, and environmental, is of interest. In the previous exergy-based analyses of the olefin process, analysis of the steam system along with the other sections is ignored. In this work, for the first time, exergetic, exergoeconomic, and exergoenvironmental analyses of an existing industrial olefin plant with ethane feedstock, at both design and working conditions, are performed. The environmental impacts are calculated through Life Cycle Assessment (LCA). The formation of cost and environmental impact in the plant are indicated through Sankey diagrams. The results indicated that the cracking section (66%), steam system (14%), and ethylene purification section (8%), respectively, are the main contributors to the total exergy destruction. It was illustrated through exergoeconomic analysis that the monetary cost of a product can be very lower/higher than its real exergy-based value. The optimization of the process aiming at the minimum specific total cost rate, the minimum specific total environmental impact rate, or a combination of them per unit of mass of useful products is suggested.