Hydrodynamic characterization of tubular reactors-contactors equipped with screen-type static mixers -

Abstract

This work discusses the characteristics of a single phase liquid and two-phase gas-liquid flow through tubular reactors-contactors equipped with screen-type static mixers from a hydrodynamic and macromixing perspective. The effect of changing the screen geometry, number of mixing elements, reactor configuration, and the operating conditions, were investigated by using four different screen types of varying mesh numbers. For this reason, in the single phase flow study, pressure drop was measured over a wide range of flow rates (2,300 ≤ Re ≤ 21,500) and was found to increase with a decreasing mesh opening. Friction factor values are also reported in the work, but when compared to other types of motionless mixers, screen-type mixers were found to require much lower energy requirements with very low recorded Z values (1.15 ≤ Z ≤ 5) that are two to three orders of magnitude lower than those reported for other motionless mixers. While in two-phase gas-liquid flow study, pressure drop was measured over a wide range of flow rates (11,500 ≤ Re ≤ 28,000) and was found to increase with a decreasing mesh opening. However, the efficient dispersion of the gas phase in the presence of screens and the consequent generation of microbubbles, was found to reduce the drag coefficient of the screen and hence reduce the pressure drop with an increase in the gas holdup. Furthermore, in the single phase liquid phase study, residence time distribution experiments were conducted in the transitional and turbulent regimes (2,300 ≤ Re ≤ 11,500), where they were conducted in the turbulent regime (18,900 ≤ Re ≤ 29,200) in the gas-liquid flow study. Using a deconvolution technique the RTD function was extracted in order to quantify the axial-longitudinal dispersion. In both single phase liquid and two-phase gas-liquid flow studies, the findings highlight that regardless of the number and geometry of the mixer, reactor configuration, and-or operating conditions, axial dispersion coeffi