Packing versus cavity: Zone-Specific contributions to mass transfer in rotating packed bed absorption process

• Two-zone absorption process was investigated in a rotating packed bed device • Two packing sizes and three casing sizes were tested • Special liquid interceptor was designed to determine zone-specific mass transfer • Cavity zone hydrodynamics had significant impact on process efficiency • Cavity zone contributed by up to 46 % of total mass transfer A pilot-size rotating packed bed unit has been equipped with an infrared system for liquid phase analysis and a special interceptor that allows for online sampling of the absorbent solution at two points in the RPB: the outer periphery of the packing and the liquid outlet. Such a system allows to determine specific contributions of the packing zone and the cavity zone to the overall mass transfer. A standard chemical system of carbon dioxide and an aqueous solution of sodium hydroxide was used to determine reactive absorption efficiency under different packing and outer casing diameters, as well as varying rotational speeds, gas and liquid flow rates, and inlet absorbate concentrations. CO 2 removal up to 27 % was achieved. Depending on geometrical configurations and process conditions, the cavity zone contribution in total absorption efficiency varied between 0 % and 46 %. Outer casing diameter had deciding effect on the mass transfer in the cavity zone, but it was also significantly affected by the packing size and rotational speed.