Research topics

Digital Capacitance Transducer for ECT System

Electrical capacitance tomography (ECT) has found successful applications in the industrial sector over the past few decades, including two-phase flow measurement, visualization of concentration distribution for gas-solid two-phase flow in pipelines, flame monitoring, and fluidized bed management. By observing variations in capacitance between the electrodes set on the boundary of a pipeline or vessel, ECT can create cross-sectional images of the permittivity distribution and, subsequently, the material distribution.

The nature of industrial processes is frequently dynamic and undergoing rapid changes. Therefore, an ECT system should not only be accurate but also fast. Efforts to improve the accuracy and speed of the ECT systems have taken two forms or directions, on the hardware and software sides. On the hardware side, the speed of data acquisition must be improved. In light of this, the ECT hardware should possess both high speed and high accuracy advantages.

The AC – based capacitance transducer is the most accurate among the available transducers in the industry but has limited speed. Initial implementation used PSD techniques to improve their accuracy deployed in analogue form. This limits its speed performance because of the LPF, part of the PSD, which has a long settling time, and brings instability to the circuit when the LPF operated in higher orders. Advances in electronics, particularly in Programmable Logic Devices (PLD) have made it affordable to implement digital PSD which basically bypasses the LPF to improve its speed of response at a reasonable computation cost. This work intends to investigate the application of digital PSD to improve the speed of ECT hardware.