Model-based optimization of sulfur recovery units

•The integrated optimization of sulfur recovery and steam generation of a sulfur recovery unit is solved.•A comprehensive kinetic model for the thermal reactor and waste heat boiler applied to a process simulation is refined and adopted.•The recombination effect within the waste heat boiler is included in the study.•Sensitivity analysis of the main operating parameters is performed.

Multi-scale process modeling is very appealing methodology for process optimization since it highlights certain issues that remain unexplored with conventional methodologies and debottlenecks certain potentialities that remain unexploited in chemical plants. In this work, a kinetic model with 2400 reactions and 140 species is implemented in a proper reactor network to characterize the thermal furnace and the waste heat boiler of sulfur recovery units; the network with detailed kinetics is the kernel of a Claus process simulation that includes all the unit operations and the catalytic train. By doing so, reliable estimation of acid gas conversion, elemental sulfur recovery, and steam generation is achieved with the possibility to carry out an integrated process-energy optimization at the total plant scale.