Optimisation of an industrial high-temperature thermal shell-and-tube heat exchanger: a petrochemical case study

Abstract

This study presents computational fluid dynamics (CFD) evaluation of Syltherm 800 and ethylene glycol as shell-side working fluids in a shell-and-tube heat exchanger (STHE) used for feedstock preheating in a petrochemical facility. The major objective was to enhance thermal efficiency while minimizing pressure drop and pumping power in energy-intensive operations at Indorama Eleme Petrochemicals Company Limited, Nigeria as a case study. A three-dimensional steady-state CFD model was developed in COMSOL multiphysics using the Navier–Stokes and energy equations under turbulent flow conditions. Ethylene glycol at 120°C was used as the baseline case and compared with Syltherm 800 at 120°C, 300°C, and 350°C. Results showed that Syltherm 800 significantly improved the thermal performance at elevated temperatures; while ethylene glycol at 120°C produced a total heat flux of approximately 9.1kW with an inlet pressure of 3,197Pa, Syltherm 800 at 350°C achieved a heat flux of 30.996kW and reduced inlet pressure to 1,676Pa. Further, the tube-side outlet water temperature increased from 35.28°C (ethylene glycol) to 44.03°C (Syltherm 800 at 350°C). The findings revealed that Syltherm 800 enhances heat transfer while reducing hydraulic resistance. The research work established the required fluid material to be used for optimal performance of the case studied industrial heat exchangers for high-temperature petrochemical applications.