High-temperature electrical capacitance tomography for gas–solid fluidised beds

Electrical capacitance tomography (ECT) is a non-intrusive and non-invasive imaging technique for the visualisation of material distribution, e.g. in a gas–solid fluidised bed. So far, ECT has been successfully used in gas–solid fluidised beds at ambient temperature. However, ECT has been rarely used in high-temperature gas–solid fluidised beds, which is of practical importance in many applications. Considering that most fluidised bed reactors are operated at high temperature, it is necessary to investigate the application of ECT in high-temperature industrial processes. In this work, a high-temperature ECT sensor, which can withstand 1073 K, is designed and fabricated. It has been verified by three stationary objects. The results show that the ECT sensor can give satisfactory images at different high-temperature levels and the change in temperature has little effect on the signal-to-noise ratio. It has also been found that the minimum bubbling velocity estimated by ECT is the same as that obtained by pressure drop measurements, and two fluidisation regimes, i.e. bubbling and slugging can be identified by ECT.