ENERGY-EFFICIENT HEAT INTEGRATION IN CATALYTIC REFORMING: A GAMS-BASED MILP OPTIMIZATION APPROACH

Abstract

Energy integration plays a crucial role in improving the efficiency and sustainability of petroleum refineries, particularly in catalytic reforming unit (CRU), which is among the most energy-intensive processes. This study presents the design and simulation of an integrated Heat Exchanger Network (HEN) for a CRU using the General Algebraic Modelling System (GAMS). Accurate process stream data, supply/target temperatures, heat capacity flow rates, and enthalpies were extracted and validated. Pinch analysis was applied to identify minimum utility targets, serving as a baseline for optimization. A Mixed-Integer Linear Programming (MILP) model was developed to optimize stream matching and reduce external utility demand. The model was implemented in GAMS and solved using CPLEX. Composite curves, heat cascade diagram, and sensitivity analyses were used to evaluate performance. Results showed significant energy savings, with hot and cold utility needs reduced by 57.1 % and 62.8 %, respectively, compared to conventional systems. The optimized network comprised 12 exchangers with stream splits, enabling effective heat recovery. A 10 °C minimum temperature difference was identified as the best compromise between energy savings and capital cost. This integrated approach combining pinch analysis and MILP optimization effectively enhances refinery energy efficiency and supports broader sustainability goals.