Evaluation of Excitation Strategies for 3D ECT in Gas-Solids Flow Measurement

The aim of this paper is to investigate the influence of different excitation strategies on the performance of a multi-plane electrical capacitance tomography sensor, used for measuring the gas-solids flows in a circulating fluidized bed. Three excitation strategies, including single-electrode excitation, dual-electrode excitation in the same plane, and dual-electrode excitation in different planes, are considered for comparison. Sands are used as the solid material. The airflow velocity is changed from 0.6 to 3.0 m/s with a step of 0.2 m/s. The capacitance data under different operating conditions and different excitation strategies are collected and used to reconstruct the permittivity distribution by a linear back projection algorithm. According to the reconstructed permittivity distribution, the solid concentration is calculated, and the bubble image, bubble diameter, and bubble velocity are estimated. According to the signal-to-noise ratio of capacitance data and the bubble properties referenced to the theoretical values, the performance of the excitation strategies is evaluated.