A comparative study between electrical capacitance tomography and time-resolved X-ray tomography

Abstract

Modern day tomographs enable the research community to investigate the internal flow behaviour of a fluidized bed by non invasive methods that partially overcome the opaque nature of a dense bubbling bed. Each tomographic modality has its own limitations and advantages and in the present study two modern day tomographic systems were evaluated with respect to their performance on a cold dense fluidized bed. The two tomographs investigated are an Electrical Capacitance Tomography (ECT) tomograph and a time-resolved X-ray tomography tomograph. The study was performed on spherical glass particles with various particle size distributions that could mainly be classified as Geldart B or D particles. Two experimental towers were employed, one with a diameter of 10.4cm and the other 23.8cm while compressed air was used as fluidizing fluid during all of the experiments.Results obtained with both systems are provided in comprehensive figures and tables and some first results are obtained with the time-resolved X-ray tomography system. The bubble size measurements of both tomographs are compared with several theoretical correlations via the root mean square error of the predictions (RMSEP). With the results it was also concluded that a small amount of small particles can noticeably alter the fluidization hydrodynamics of a powder. The bubble frequencies are also presented to aid in understanding the hydrodynamic behaviour of the powders investigated. A comprehensive summary of the two tomographic modalities is also provided.

X-ray measurements on the influence of optical probes on gas–solid fluidized beds

“…Currently, it is still investigated by many researchers with different methods (Maurer et al, 2013;Rautenbach et al, 2013). Fig.…”

Fast X-ray tomography for the quantification of the bubbling-, turbulent- and fast fluidization-flow regimes and void structures

“…XRT is a hard field technique: the direction of a field line is not changed by the medium. Rautenbach et al [12] report a comparative study between ECT and XRT. Recent advances in fast XRT makes it possible to implement time-resolved cross-sectional measuring in fluidized beds [1].…”

Co-operative sensor fusion using time warping in multimodal tomometry for process control

“…Since fluid component involved with most of the fluidised bed applications are non conductive, ECT is more suitable for measurements and flow visualizations. (Rautenbach et al 2011) and (Rautenbach et al 2012) explain experimental studies on fluid particles and their influences in parameters using ECT and x-ray tomographic techniques. Investigations of pneumatic conveying of solid particles has also been done by (Dyakowski & Jaworski 2003) and .…”