Exergy optimization approach for improving indirect total site heat integration

Abstract Heat integration is the most established area of process integration and has therefore gained increasing importance in recent decades. Unlike direct methods that deal with the direct heat exchange between streams, indirect HI is achieved through heat exchange via an intermediate medium. This method can be particularly beneficial in interplant or intersectoral applications. A purposeful and systematic use of non-isothermal mixing of streams in the intermediate heat recovery circuit is introduced in this work. Optimization based on exergy was used for the optimization of the HI system. An industrial case study was selected to demonstrate the advantage of the proposed method. The findings indicate considerable potential and show promising outcomes, including a significant 28.8 % decrease in utility demand, alongside a reduction in the number of required units, underscoring the effectiveness and practicality of the proposed methodology.