(406a) Development of Turbulence Measurement Technique Using Electrical Resistance Tomography for Multiphase Flows

Turbulence affects every aspect of our life, from atmospheric and oceanic flows, to transport of fluids all the way to a multitude of essential industrial processes. However, it has always been an enormous scientific challenge to quantify turbulence for multiphase flows due to their complex features and the lack of diagnostic tools, especially when the system is of three phases (solid, liquid and gas) such as the pulp phase in flotation cells employed for minerals recovery. Turbulence plays an important role in the flotation process since it affects the three main sub-processes: air dispersion, particle suspension and bubble-particle collection interactions. Entrainment of fine particles is also affected by turbulence. Quantification methods for turbulent flows require the measurement of the fluctuating (mass, constituent’s phase, heat, momentum, energy) transport properties at a sufficiently high spatial and temporal resolution. Electrical resistance tomography (ERT) has been applied to a wide range of scientific and engineering fields such as geophysical study, clinical diagnosis, chemical or mineral process measurement and optimization. When air bubbles in flotation cells move through the ERT sensor plane, the conductivity distribution fluctuates with turbulence. By measuring these fluctuations, turbulence information can be extracted by using a Green-Kubo method. ERT has been applied to measure turbulence profiles in a 60-liter air/water flotation cell, a 3m³ air/water flotation cell and a Metso 3m³ industrial flotation cell (as shown in Figure 1). The results showed agreement with turbulence measurement technique using piezoelectric vibration sensor. This ERT turbulence measurement technique for the multiphase flows can be potentially used to wider industrial applications.