Electrical Capacitance Tomography- from Principle to Applications

Among various industrial tomography modalities, electrical capacitance tomography (ECT) is the most mature and has been used for many challenging applications. ECT is based on measuring very small capacitance from a multi-electrode sensor and reconstructing the permittivity distribution in a cross section of an industrial process. Compared with other tomography modalities, ECT has several advantages: no radioactive, fast response, both non-intrusive and non-invasive, withstanding high temperature and high pressure and of low-cost. Because of very small capacitance to be measured (much smaller than 1 pF) and the “soft-field” nature, ECT does present challenges in capacitance measurement and solving the inverse problem. The latest AC-based ECT system can generate online images typically at 100 frames per second with a signal-to-noise ratio (SNR) of 73 dB. Examples of industrial applications include gas/oil/water flows, wet gas separation, pneumatic conveyors, cyclone separators, pharmaceutical fluidised beds, and clean use of coal by circulating fluidised bed combustion and methanol-to-olefins conversion. During this tutorial, ECT is discussed from principle to industrial applications, together with demonstration of an AC-based ECT system. Keywords: electrical, capacitance, tomography, IEEE, IMS, Wugiang Yang, tutorials, education, applications