Process characteristics for a gas—liquid system agitated in a vessel equipped with a turbine impeller and tubular baffles

Abstract

Results of the experimental research on gas hold-up, power consumption for liquid phase and gas—liquid systems, and on residence time of the gas bubbles are presented in the paper for an agitated vessel with a turbine impeller. Distilled water or aqueous solutions of NaCl were used as the liquid phase. Air was dispersed into liquid as the gas phase. The studies were carried out in an agitated vessel of the inner diameter D = 0.634 m. Tubular baffles of the diameter of 0.7D, consisting of 24 vertical tubes of the diameter of 0.016D, were located inside a flat-bottomed tank. Turbines with six blades and the pitch of 90°, 60°, or 45°, respectively, were used for agitation. Measurements were carried out in the range of good dispersion of gas bubbles in the liquid within the turbulent regime of the liquid flow. Effects of the gas bubbles capability to coalesce on the gas hold-up, residence time of the gas bubbles, and power consumption were analyzed. Results of the power consumption (P G-L/P o = f 1(Kg, Fr)) and gas hold-up (φ= f 2(Kg, We, Y)) were approximated mathematically, using Eqs. (5) and (6), respectively. In Eq. (6), parameter Y was introduced in order to describe the influence of the bubbles capability to coalesce on the gas hold-up. The results of the study show that power consumption does not depend on the capability of bubbles to coalesce, but the pitch of the turbine impeller affects the power characteristics in such a physical system significantly. However, the residence time of the gas phase in agitated liquid depends on the pitch of the impeller blade and on the capability of bubbles to coalesce.

Hydrodynamic Characteristics of Mechanically Agitated Air - Aqueous Sucrose Solutions

“…Dispersion of gas in liquid depends also on the type, size and location of gas sparger (Bao et al, 2012;Fasano et al, 2011;Kamieński and Niżnik, 2002;Kamieński, 2004;Major-Godlewska and Karcz, 2011;Moucha et al, 2003;Paglianti, 2002;Shewale and Pandit, 2006;Vinnett et al, 2012;Warmoeskerken, 1986;Yianatos et al, 2010). For gas-liquid systems, single impellers or impeller sets generating radial-axial circulation of the fluid in a vessel are often used.…”

A General Review of the Current Development of Mechanically Agitated Vessels

“…In gas-liquid systems generated in a vessel with one or more impellers, the primary target is to obtain uniform gas dispersion throughout the whole volume of the liquid. As show literature studies, the dispersion depends on the type, size and location of gas sparger [74,75].…”

Chemical and Process Engineering

“…• geometric parameters -vessel and impeller diameter, height of the liquid, impeller type, number of impellers etc. (Busciglio et al, 2013;Cooke and Heggs, 2005;Cudak, 2011Cudak, , 2014Niranjan, 1999, 2002;Major and Karcz, 2011;Major and Radecki, 2018;Moucha et al, 2003;Mueller and Dudukovic, 2010;Nocentini et al, 1993;Petricek et al, 2018, Pinelli et al, 2003Takriff et al, 2000;Wan et al, 2016;Vasconcelos et al, 2000;Xie et al, 2014;Yawalkar et al, 2002a),…”