Analysis of axial dispersion in an oscillatory-flow continuous reactor

Abstract

Experimental results of axial mixing for single-phase flow in pulsed sieve plate column (PSPC) were presented and discussed. The study is aimed at the use of the PSPC as a new type of oscillatory-flow tubular reactor for emulsion polymerization processes. The effects of pulsation frequency and amplitude, flow rate, plate spacing and fluid viscosity were studied. Axial dispersion coefficients were determined by fitting the axial dispersion model to the measurements of residence time distribution. A total of 213 runs were carried out with water at 20 °C, covering the range of pulsation frequency from 0 to 4.5 s −1, amplitude of pulsation from 5 to 25 mm, plate spacing 25, 50 and 100 mm, and water flow rate from 3.8 to 11.8 l/h. The results show that, under absence of pulsation, axial dispersion increases with flow rate and exhibits a maximum with respect to the plate spacing. For pulsed (oscillatory) flow, axial dispersion coefficient increases with amplitude and frequency of pulsation, and the effect of plate spacing is dependent of the pulsation velocity. Additional 39 experiments for pulsed flow were performed with aqueous solution of poly(vinyl alcohol) with viscosity varying in the range 1.4–10.0 cP. The results show that the axial dispersion decreases with plate spacing, increases with the viscosity for plate spacing 25 mm and is nearly independent of viscosity for plate spacing 50 and 100 mm. A correlation proposed in the literature was tested.