Comparison of the Isomerization Units from the Perspective of Process Design and Energy Studies for Producing High Quality Gasoline

Articles in Press

Document Type : Research Article

Authors

Department of Chemical Engineering, Faculty of Engineering, University of Kashan, Iran

Abstract

Optimizing energy consumption and gasoline quality in isomerization units has become very important, indicating the need to employ suitable process design methods and energy studies. Aspen HYSYS, Aspen Energy Analyzer, and Aspen Pinch software were utilized for simulation. Optimum heat integration opportunities were identified using composite curves and driving force plots. This study showed significant variations in the minimum approach temperature (ΔTmin.) among the units. Unit 1 showed the lowest ΔTmin. at 8 °C, followed by units 2 and 3 at 9 and 10 °C, respectively. Consequently, unit 1, with 35.65 MW of hot and 41.24 MW of cold utilities consumption at ΔTmin.= 8 °C, demonstrated the highest potential for heat recovery when increasing ΔTmin. from 8 to 10 °C. The first heat recovery scenario aimed to examine the Research Octane Number (RON) of the output stream from the DIP column, and the amount of isopentane recovery to improve the existing processes. Unit 2 has an octane number and isopentane recovery of 85 and 75.24%, respectively, which is the lowest amount among the three units. Economic analysis using Aspen Process Economic Analyzer revealed that unit 1 had the highest fixed (7.6×106 USD), operating (7.48×106 USD/year), and total costs (13.75×106 USD/year). The second scenario showed that 17% and 20% of the total required low pressure steam in Unit 1 and Unit 2 can be provided due to steam generation using process energy pockets, respectively. Results showed that the process design and operating conditions directly influence energy and RON.

Keywords

Chemical Process Design

Articles in Press, Accepted Manuscript
Available Online from 29 August 2025

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