Intensification of the G/L absorption in microstructured falling film application to the treatment of chlorinated VOC's. Part III: Influence of gas thickness channel on mass transfer - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Chemical Engineering Science Année : 2011

Intensification of the G/L absorption in microstructured falling film application to the treatment of chlorinated VOC's. Part III: Influence of gas thickness channel on mass transfer

Résumé

A falling film micro-absorber (FFM) is used to treat gas effluents containing a chlorinated VOC. In such operation, mass transfer can be enhanced by optimizing micro-absorber geometry and operating conditions. Firstly, the influence of gas cavity thickness and gas flow rate on absorption performances, were investigated. Experimental study is performed for a range of cavity thickness between 2 and 6 mm and gas flow rate between 45 and 390 N mL/min. Results showed a significant improvement of absorption rate when cavity thickness is reduced, especially for low gas velocities. Indeed the global mass transfer coefficient K(G)a can be multiplied by 7 when cavity thickness is divided by a factor of 3. The mass transfer is then intensified and apparatus compactness is enhanced. The modeling of gas/liquid mass transfer (Monnier and Falk, 2011) indicated that mass transport is performed mainly by diffusion. A new simulations showed an important axial dispersion in gas concentrations profile when gas flow rate and gas cavity thickness are relatively high (t(G)=5-6 mm, G(V)>400 N mL/min). Then, to optimize micro-absorber performances, the integration of gas turbulence promoters must be considered. The second part of this paper concerns the characterization of gas-side mass transfer in the FFM. A dimensionless correlation is developed: Sh(G) = 2.04Re(G)(0.23)Sc(G)(0.5)(t(G)/Z)(0.17) When compared to other relations found in literature, this correlation characterizes gas laminar flow in this kind of micro-structured device.

Dates et versions

hal-00777329 , version 1 (17-01-2013)

Identifiants

Citer

Neila Mhiri, Hubert Monnier, Laurent Falk. Intensification of the G/L absorption in microstructured falling film application to the treatment of chlorinated VOC's. Part III: Influence of gas thickness channel on mass transfer. Chemical Engineering Science, 2011, 66 (23), pp.5989-6001. ⟨10.1016/j.ces.2011.08.021⟩. ⟨hal-00777329⟩
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