A study on the instability of coherent mixing structures in a continuously stirred tank
2000 (English)In: Chemical Engineering Science, ISSN 0009-2509, E-ISSN 1873-4405, Vol. 55, no 23, 5657-5670 p.Article in journal (Refereed) Published
Mixing of an inert marker added to the bulk region of a Rushton-turbine-agitated reactor was investigated by planar laser-induced fluorescence. The effect of the turbine agitation speed on the mixing process was initially studied statistically. Average concentration fields, calculated at several sections of the reactor, revealed the general spreading of the contaminant. This approach, however, was found to be unsatisfactory in studying the mechanisms of macro-mixing in the reactor because of the strong intermittence in the flow. Therefore, the concentration data were analysed using conditional techniques, namely the dynamic structural concept, so as to identify the presence of coherent mixing structures and characterise them in space. Instability patterns were observed with increasing turbine agitation speed from 0.3 to 0.7 W/m(3). Using geometrical concepts, the mechanisms of this spatial instability were further described. General conclusions on the spreading of the contaminant were drawn on the basis of the how instability with respect to transport by convection and diffusion phenomena.
Place, publisher, year, edition, pages
2000. Vol. 55, no 23, 5657-5670 p.
planar laser-induced fluorescence (PLIF), dynamic structural analysis, geometrical analysis, mixing, coherent mixing structure, Rushton impeller, stirred tank, laser-induced fluorescence, jet, reactors, fields, scale
IdentifiersURN: urn:nbn:se:kth:diva-20235ISI: 000165943200009OAI: oai:DiVA.org:kth-20235DiVA: diva2:338928
QC 201005252010-08-102010-08-10Bibliographically approved