Investigation of the liquid mixing characteristic of an external-loop hybrid fluidized-bed airlift reactor

The paper presents the results of experimental investigation of the mixing characteristics of an external-loop hybrid fluidized-bed airlift reactor. Stimulus-response tracer experiments were carried out using KCl solution as a tracer. Based on the obtained tracer residence time distribution (RTD) curves, values of the Peclet number for the entire apparatus and its selected zones i.e. fluidization, bubbling, bottom and degassing zones were determined. The values of Pe were calculated using three different methods, i.e. method of moments, optimization method combined with numerical solution of the axial dispersion model and by fitting the experimental data to a special solution of the axial dispersion model describing the response of the loop apparatus to the impulse of tracer. The mixing time was determined both from the experimental RTDs and through using the proposed theoretically derived expression that permits an estimation of the values of mixing time based on a single liquid circulation. (C) 2019 Elsevier Ltd. All rights reserved.