Abstract EN:

Within the industrial framework of the gas waste processing, in particular H2S, the optimization of the Clauspol type units requires the substitution of random packing by structured packing. Structured packing are of recent use, and it is necessary to acquire a better knowledge of the hydrodynamics and mass transfer on such structures, which are complex because of their geometries. Gas-liquid mass transfer is studied for thin films trickling down a tilted plane surface or corrugated one. Local gas side and liquid side mass transfer coefficient, kG and kL, as well as the specific interfacial area, a, are estimated by means of experiments of reactive absorption of CO2 in a sodium hydroxide solution. The dependence of these mass transfer characteristic parameters is explored versus the geometrical properties of the streaming surfaces and the local hydrodynamic properties characterized by the flow rate and liquid film thickness. The mean film thickness is measured using an ultrasonic probe method and by the analysis of Residence Time Distribution. It is small, thinner than 1. 10-3m for a liquid film trickling over plane surface inclined at 30ʿ. On a corrugated surface, while working for angles stronger, up to 70ʿ, the thickness is larger inducing a reduction of the liquid flow velocity. Thus, the total increase in the kLa product observed while passing from a flow on a plane surface to a flow on a corrugated one, is primarily related to the effects of the corrugated geometry on the specific interfacial area. Moreover, the liquid side mass transfer coefficient kL is not very disturbed in the studied range of Reynolds numbers. It is also not very sensitive to the film geometry.