Heat Integration of Isomerization Unit Using Loop Breaking

A significant portion of operating costs in process industries is spent on energy consumption; therefore, exploring heat integration methods is essential to reduce production costs without compromising product quality or performance. In this study, process data from an isomerization unit was used to simulate the process in Aspen HYSYS (V9), and the heat integration analysis was conducted using Aspen Energy Analyzer (V9). Initially, heat exchanger data was entered into the software, and the resulting heat exchanger network (HEN) was examined. To optimize energy consumption, the pinch analysis technique—specifically the loop breaking method—was applied to eliminate redundant heat loops. As a result, the number of heat exchangers was reduced from 28 to 25. This modification led to a reduction in capital cost from $2.196×10⁷ to $2.113×10⁷ and in annual cost indicator from $2.394×10⁷/yr to $2.373×10⁷/yr. Therefore, capital and annual costs decreased by 3.77 and 0.87%, respectively. These savings are attributed to the removal of unnecessary heat exchangers, which lowered both the heat duty and the surface area required. Furthermore, the applied modifications led to a noticeable improvement in energy efficiency through better heat recovery within the system. The novelty of this research lies in the integrated use of pinch analysis and loop breaking for optimizing the HEN of a real isomerization unit—an approach rarely addressed in previous industrial studies. This method provides a practical and cost-effective model for sustainable design in process industries.