Packing surface and column internals in strippers can act as nucleation sites for high temperature nucleate boiling. This boiling can create excess mass transfer area for CO2 stripping which can result in significant reductions in capital cost of strippers and marginal improvements in energy cost. Results from this rate-based simulation study indicate that for a typical pilot scale stripper at natural gas fired flue gas conditions, boiling enhances wetted area of packing by 38% and reduces steam requirement by 2%. This significant result also indicates that design of commercial stripper columns while accounting for boiling can result in a 50-80% reduction in packing height. This study also looks into the controlling mass transfer mechanisms in pilot and commercial strippers. Preliminary results have shown that the use of coarse packing to reduce flooding in commercial columns could make the mass transfer more gas-film controlled and therefore will not promote boiling. Using finer packing could result in more liquid film control and promote boiling. This result shows that scaling up of columns based on total area of packing could result in significant under or over-prediction of mass transfer and heat transfer rates in the column. Knowledge of controlling mechanisms of the CO2 stripping process during scale-up is therefore very important.
