Measurement of Dynamic Liquid Distributions in a Fixed Bed Using Electrical Capacitance Tomography and Capacitance Wire-Mesh Sensor

Abstract

An intricate problem associated with fixed bed operation is liquid maldistribution, which denotes the fact that the liquid does not homogeneously flow through the bed. In a comparative study we evaluated two capacitance imaging methods—capacitance wire-mesh sensor and electrical capacitance tomography (ECT)—with respect to their capability of measuring static and dynamic liquid holdup in a fixed bed. The capacitance wire-mesh sensor as an invasive instrument is able to disclose flow structures at higher spatial resolution and was therefore considered the reference instrument for liquid holdup measurement. We found that both methods predict dynamic liquid holdup in the column in a similar way with only small systematic deviation. The results therefore prove that noninvasive electrical capacitance tomography can reliably measure cross-sectional dynamic liquid holdup in a fixed bed, even with a simple and fast linear back projection reconstruction algorithm.