Process simulation of CO2 absorption data fitted to performance efficiency at TCM Mongstad

Abstract

This work's first aim is to fit the simulated results to pilot plant data from Test Centre Mongstad (TCM) for both high and low CO₂ exhaust gas inlet concentrations. The next aim is to evaluate whether fitted parameters for one scenario (a set of experimental data under specified conditions) give reasonable predictions under other conditions. The scenarios at TCM have been simulated in both a rate-based model in Aspen Plus (RateSep) and an equilibrium-based model in Aspen HYSYS. The rate-based model’s performance data were fitted by only changing the liquid hold-up factor (multiplied with the hold-up estimated by the Bravo/Rocha/Fair correlations) to obtain the experimental CO₂ removal efficiency. In the equilibrium-based model, a Murphree efficiency (E_M) was specified for 24 or 18 stages (meter of packing) to fit the CO₂ removal efficiency and the temperature profile from performance data. The specified E_M profiles were then used to fit performance data for other scenarios by adjusting only an E_M-factor, multiplying all the E_M values in an E_M profile. The performance (CO₂ removal and temperature profile) was reasonably simulated for each given scenario for all the models. It is shown in this work that the use of the liquid hold-up factor (and not the interfacial area factor) is convenient to fit the rate-based model to the pilot plant data. Using fitted parameters at low CO₂ inlet concentration to predict performance at high concentration needed an adjustment factor (liquid hold-up factor or E_M-factor) to obtain correct CO₂ removal predictions. A liquid hold-up factor of 0.72 and an E_M-factor of 1.72 fitted to performance data for high CO₂ concentration at TCM gave reasonable predictions compared to performance data for high CO₂ concentration from the Esbjerg pilot plant.