Gas absorption accompanied by chemical reaction in a system of three-phase slurry-foam reactors in series

Experiments have been performed in a semi-batch reactor for the absorption of carbon-dioxide gas in an aqueous foam-slurry containing suspended particles of calcium hydroxide. One each of cationic, anionic and non-ionic surfactants has been used as the foaming agent. Single-stage model for such a reactor, reported earlier by the present authors, agrees well with the present experimental data. The single-stage model was developed to account for the contribution of the storage section as well, instead of the foam section alone as reported in the literature, towards gas absorption and chemical reaction, considering that the storage constitutes 60–85 percent of the total liquid/slurry charged into the reactor. A system of continuous slurry-foam reactors in series has been simulated for the carbonation reaction mentioned above using the single-stage semi-batch reactor model and the material balance equations. Values of ksl and ε¯l, required for this, have been calculated from dimensionless correlations developed using the experimental data. Design charts have been presented in the form of figures. A comparison of a foam-bed reactor with other gas–liquid/gas–liquid–solid contactors in respect of important mass-transfer parameters and a critical review of the reported models of this reactor have also been presented.

Research highlights▶ Exhaustive comparison of a model foam-bed reactor with other gas-liquid contactors. ▶ Critical review of the reported models of foam-bed reactor. ▶ Carbonation of hydrated lime in bubble column and slurry-foam reactors. ▶ Higher conversion observed in foam reactor over that in bubble column reactor. ▶ Design of slurry-foam reactors in series incorporating sparingly soluble particles.