Investigation Of Coalescing System Gas-Liquid Mass Transfer Characteristic In A Multi-Impeller Hot-Sparged Stirred Reactor

Hot-sparged stirred reactors are now widely used in industrial processes such as petrochemisty, biotechnology, metal smelting, wastewater treatment etc. for the advantages of large gas-liquid interfacial area, intense mass&heat transfer ability, controllable manufacturing expense, and stable operating performance. However, researches on fluid mixing characteristics in hot-sparged stirred reactors are especially inadequate that engineers are still used to designing hot-sparged stirred reactors with the same methods for cold-gassed reactors.This paper starts the survey on gas-liquid dispersion characteristics of coalescing system. The experiment is conducted in a300mm diameter stirred vessel with a standard elliptical head, the agitator is made up by a hollow blade dispersing turbine below two up-pumping hydrofoils. The experimental results show that under hot conditions relative power demand (RPD) increases as the increase of temperature while total gas hold-up decreases on the contrary. Two empirical correlations respectively for gassing power number and total gas hold-up calculation are obtained for industrial reference.The volumetric mass transfer coefficient (kLa) is systematically studied under the same experimental set. The result shows that kLa increase significantly as stirrer power input (Pm) and superficial gas velocity (Vs) increase. Pm has more influence on kLa than Vs, while temperature causes slightly change on kLa; kLa is correlated on the dependence of TK, Pm, Vs. Further investigation is taken on data independence analysis of the kLa correlation as well as its application. The results shows that the kLa correlation predicts well under conditions out of the experimental TK and Vs range, which provides certain value for experiment design and kLa correlation use in practice.