Effect of Preheating Inlet Air and Acid Gas on the Performance of Sulfur Recovery Unit—CFD Simulation and Validation

Abstract

Combustion temperature is a key factor that directly influences the performance of a sulfur recovery unit (SRU); the prevalent low temperatures in SRU cause deactivation of catalysts and eventual darkening of produced sulfur. As part of the ongoing work to improve the performance of a real SRU reactor (Abadan Oil Refinery, Iran), this study was focused on the effect of preheating inlet air and acid gas (individually and concurrently) on combustion temperature, sulfur recovery, and amount of contaminants. The Claus reaction furnace of the SRU was modelled and simulated by Ansys-Fluent software; k‑e, eddy dissipation, and P1 models were used to model turbulent flow, combustion, and radiation respectively. The numerical predictions of reactor temperature and mole fraction of products were validated with the experimental data. The results confirm that, preheating of inlet air and acid gas increases combustion temperature and sulfur recovery, and reduces the amount of contaminants such as COS, and CS2. Moreover, simultaneous preheating of inlet and acid gas is more effective in improving the combustion temperature, compared to the individual preheating cases. A six-step chemical kinetics was used for the purpose of numerical simulation, which yielded more accurate predictions in comparison to previous works.