Intensifying micromixing in a semi-batch reactor using a Rushton turbine

• Published in: Chemical engineering science 2005-04, Vol.60 (8), p.2333-2339
• Main Authors: Assirelli, Melissa, Bujalski, Waldemar, Eaglesham, A., Nienow, A.W.
• Format: Article
• Language: English
• Subjects: Applied sciences; Chemical engineering; Competing fast reactions; Exact sciences and technology; Intensification; Micromixing; Mixing; Reactors; Rushton turbine; Semi-batch reactor
• ISSN: 0009-2509; 1873-4405
• DOI: 10.1016/j.ces.2004.10.041

The ‘iodide–iodate’ reaction scheme has been used to ascertain the effectiveness of micromixing in a semi-batch reactor when feeding with pipes rotating and discharging continuously into the region of highest local specific energy dissipation rate, ε T . The results are compared with those obtained using a fixed pipe at the equivalent position and at other positions including near the top surface, the most convenient position industrially. The results show significant intensification, i.e., a seven-fold reduction in ‘waste product’, between the most convenient fixed feed pipe position and the rotating pipes, even at the modest specific power input of ∼ 1.0 W / kg . This mode of addition also ensures that feeding is always into a constant value of ε T , whereas with a static pipe close to the impeller the reactants are being fed in a region where ε T varies cyclically. This difference in the ε T values experienced by the two modes of addition poses problems for previous models of micromixing in the literature linking selectivity to local specific energy dissipation rates.