Thermal-Hydraulic Analysis of a Shell-and-Tube Heat Exchanger Due to Fouling in the Distillation Process Using aspen plus

Abstract

Fouling is a chronic problem in heat exchangers, and traditional analysis methods often require significant effort, making them time-consuming and impractical for industrial settings. This study uses aspen plus software to analyze fouling in a shell-and-tube heat exchanger that preheats feed for a distillation column. The objective of this study is to compare design, rating, and simulation modes to assess tube-side fouling, interactions between thermal and hydraulic analyses, and its impact on distillation column operations, including the cost increase due to fouling. Cases include a clean scenario, four with varying fouling resistances, and four with varying fouling layer thicknesses. The findings indicate that while design mode is informative, it is impractical for real-time analysis. Rating mode identifies potential malfunctions, but simulation mode proves superior by providing real-time data. Based on simulation results, the available heat duty decreases almost linearly with increasing fouling resistance, resulting in a maximum decrease of 31.25%. As the fouling resistance increased, the shell-side outlet temperature also rose from 69.17 °C to 75.75 °C, while the tube-side outlet temperature dropped from 60 °C to 49.35 °C. This prevented the heat exchanger from reaching the required inlet temperature for the distillation process, leading to an increase in reboiler duty. This study concludes that using the appropriate mode allows for addressing fouling with a simplified, reliable approach, even without historical plant data or the need to engage in complex mathematical methods.