Simulation Study on Determination of Gas-Liquid Profile in an Aeration Tank for Mixing Process by using an Electrical Capacitance Tomography System

Nur Tantiyani Ali Othman, Muhammad Danial Najmi Ronizan

Abstract

As an electrical capacitance tomography (ECT) is a non-intrusive and non-invasive technique, it has been used a lot in industrial applications such as fluidized beds, palm oil processing industry, gas/solids cyclones and oil and gas industry. It was found that the developing process of the ECT hardware takes a longer time and it requires specialized technical skills to design it. Thus, a simulation technique was studied as it can be executed in a short period of time as compared to the experimental approach. In this study, 3D ECT model system was developed using COMSOL^® Multiphysics software where the sensors consist of 16 electrodes allocated around the outer layer of the tank with a diameter of 110 mm and height of 180 mm. To observe a flow pattern and gas hold-up in the gas-liquid multiphase flow, three parameters were manipulated; the feed of a hot air velocity that range of 0.01-0.1 ms^-1, types of inlet gas (carbon dioxide gas, oxygen gas and hydrogen gas) and an electrical charge voltage ranging from 1-15V. The simulation results show that the average velocity increased as the feed of the hot air was increased. Besides, the lowest value of the gas hold-up was observed as the hydrogen gas was used as the feed, meanwhile there was no noticeable difference between carbon dioxide and oxygen gas due to a lower gas density. In addition, no significant difference was indicated when the electrode was charged at different voltage of 1V, 5V and 15V. From these results, the optimum condition for average velocity and gas hold-up was determined that can be used to develop the ECT model in the future for mixing process purpose.