Multiple steady states detection in a packed-bed reactive distillation column using bifurcation analysis

A packed reactive distillation column producing ethyl tert-butyl ether from tert-butyl alcohol and ethanol was simulated for detection of multiple steady states using Aspen Plus®. A rate-based approach was used to make the simulation model more realistic. A base-case was first developed and fine-tuned to fit experimental data. Sensitivity analyses were then performed for reboiler duty and distillate molar flow as continuation parameters to trace the respective bifurcation curves in the region of multiplicity. The results show output multiplicity at three distinct steady states at high reboiler duties. Input multiplicities were detected at high reflux ratios. Temperature and composition profiles of the solution branches were analyzed to identify the stable and desirable steady state. The optimum operating point was determined to be at a reboiler duty of 0.38 kW and a reflux ratio of 5–7. These results closely match the experimental results.