Chemical Engineering Science, Vol.65, No.24, 6425-6434, 2010
Intensification of G/L absorption in microstructured falling film. Application to the treatment of chlorinated VOC's - part I: Comparison between structured and microstructured packings in absorption devices
The absorption of tetrachloroethylene - the VOC - in di-ethyl-hexyl-adipate - the solvent - was carried out as an example of gaseous waste treatment. Two gas-liquid contactors were used: a column provided with as structured Sulzer EX (R) packing and a microstructured falling-film absorber provided with thin vertical channels, manufactured by the Institut fur Mikrotechnik Mainz (IMM). The overall transfer coefficient of VOC, K(G)a, was calculated from the absorption efficiency of the various runs carried out, allowing comparison of the two gas-liquid contactors. Due to the high solubility of the considered VOC, mass transfer was shown to be mainly controlled by gas-side transfer rates. Transfer coefficient K(G)a of the two absorbers were found to be comparable, but with gas and liquid velocity in the microstructured absorber from one to two orders of magnitude below those in the column, expressing the high transfer performance offered by the microsystem. Moreover, the thickness of the liquid film in the channels was below 100 mu m, much lower than that in a structured packing near 500 mu m. This shows that lower liquid flow rates can be used for efficient absorption in the microsystem. It is shown that contrary to conventional structured packing, the designed contact specific area in the microabsorber strictly corresponds to the interfacial G/L surface. This enables more compact and to miniaturize G/L contactors to be designed. (C) 2010 Elsevier Ltd. All rights reserved.
Keywords:VOC;G/L absorption;Structured packing Sulzer EX (R);Microstructured contactor;Falling film microreactor IMM;Tetrachloroethylene