Imaging of Mixing of Two Miscible Liquids using Electrical Impedance Tomography

J. Kourunen1, L. M. Heikkinen1, M. Vauhkonen1, R. Käyhkö2, J. Matula2, J. Käyhkö3

1. Department of Physics, University of Kuopio, P.O.Box 1627, FIN-70211 Kuopio, Finland, Email: lasse.heikkinen@uku.fi

2 . Wetend Technologies Ltd, Kaartilantie 7, FIN-57230 Savonlinna, Finland,

3. Lappeenranta University of Technology, FiberLaboratory, Vipusenkatu 10, FIN-57200 Savonlinna

ABSTRACT

The objective of this paper is to study the mixing of two miscible liquids in turbulent flow. Strictly speaking, we are studying the performance and mixing patterns of TrumpJet® mixing system of papermaking chemicals and additives. TrumpJet® is a jet injection mixer developed and produced by Wetend Technologies Ltd. The studies are made in cooperation with the company. As a monitoring system, we use an electrical impedance tomography system developed at the Department of Physics, University of Kuopio. In this study only eight current injections are used and 64 corresponding voltages are measured. The frame rate of the system is about 40 frames/s. The difference reconstruction approach is used to produce three-dimensional images of the conductivity distribution. In order to quantify the quality of mixing, a mixing index is calculated based on the reconstructed images. Laboratory tests are performed in a pilot plant. We compare the mixing of chemicals to the main flow with TrumpJet technology to the conventional chemical injection system.

Keywords Electrical impedance tomography, liquid-liquid mixing, 3D-imaging