Electrobalance and fixed-bed reactors have been used to study the capture of CO 2 from simulated flue gas using a regenerable Na 2 CO 3 sorbent. CO 2 capture was effective in the temperature range of 60-70 °C, while regeneration occurred in the range of 120-200 °C, depending on the partial pressure of CO 2 in the regeneration gas. Equal molar quantities of CO 2 and H 2 O are produced during sorbent regeneration, and pure CO 2 suitable for use or sequestration is available after condensation of the H 2 O. Capture of as much as 90% of the CO 2 was possible at appropriate reaction conditions, and little or no reduction in either carbonation rate or sorbent capacity was observed in limited multicycle tests. The concept is potentially applicable to the capture of CO 2 from existing fossil fuel-fired power plants, where amine scrubbing is the only CO 2 capture process currently available.

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Experimental data from both smalland large-scale turbulent contacting absorbers (TCA) and spray columns used in the wet scrubbing of SO2 from flue gases have been analyzed to obtain the gas film mass transfer coefficients and the overall coefficients in the liquid film which includes chemical reaction in the liquid film. The scrubbing slurries investigated are recycled limestone-magnesium oxide-water slurries. The gas film coefficients for the spray and TCA scrubbers were calculated from data on SO2 scrubbing with sodium carbonate solutions. The overall mass transfer resistances in the liquid phase for both scrubbers were correlated in terms of the ratio of the gas film and liquid film mass transfer resistances. Over the range of variables studied and within the accuracy of the experimental data, the ratio of the resistances was found to be a function of only the scrubber type, the inlet SO2 partial pressure in the gas phase, and inlet pH and magnesium concentration of the scrubbing slurry. Specifically, it was found that the ratio of the gas and liquid film mass transfer resistances or the fraction to which SO2 removal is gas film controlled increases with increasing slurry pH and magnesium concentration and with decreasing S02 partial pressure. The correlations for the gas film mass transfer coefficient and the ratio of mass transfer resistances developed in this paper can predict within 5% the experimentally observed SO2 removal efficiencies for widely differing size TCA and spray column scrubbers.