Kinetics of a catalyzed semi-batch ethoxylation of nonylphenol

Numerical simulations of the reactive mixing in a commercially operated stirred ethoxylation reactor

“…The blade height w was 0.32D and the blade width l was 0.25D. The impeller was rotated at a speed that corresponded to a Reynolds number of 7000 with a working fluid of the density of 928 kg/m 3 and viscosity of 4.0 × 10 −3 kg/ms based on a kinetic experiment Wu and Patterson (1989). conducted earlier by the authors (Chiu et al, 2000;Chiu, 2005). Although the Reynolds number gave a transition flow regime for this flow where it was turbulent at the impeller region and laminar in remote parts of the vessel (Perry and Green, 1984), for simplicity, the k--turbulence model was still assumed to be applicable in this flow and used in the numerical model.…”

“…The kinetic mechanism of a base-catalysed nonylphenol ethoxylation has been extensively studied elsewhere (e.g., Santacesaria et al, 1990;Di Serio et al, 1995;Edwards, 1998;Chiu et al, 2000;Chiu, 2005) and hence only a brief description is given here. Readers are advised to refer to these references for detailed derivation of the reaction mechanism.…”

“…It should be noted that for the CFD simulations with the inclusion of chemical reactions, the geometry of the whole tank with ∼ 160, 000 cells was used due to the single inlet of injection of EO. The vector plot of the mean velocity, normalised with U tip , in an r--z plane midway between the two baffles for the flow generated in the laboratory autoclave at the kinetic condition used in Chiu et al (2000) and Chiu (2005) is shown in Fig. 6.…”

“…are the dissociated ions of nonylphenol and the polyethoxylated species respectively; k i and k p are the second order rate constants for the initiation stage and the propagation stage, respectively, and are expressed in the Arrhenius equation with the parameters obtained from the experiments performed previously in Chiu et al (2000) and Chiu (2005).…”

“…In the case of the laboratory autoclave, the injection of EO mass was by manually opening and closing the oxide valve as described in Chiu et al (2000) and Chiu (2005). The injection process was intermittent and the disturbance to the flow was considered insignificant (an averaged EO flow rate at 1% of the impeller tip velocity).…”