Electrical capacitance tomography measurements on the pneumatic conveying of solids

We have evaluated the usefulness of electrical capacitance tomography (ECT) as a tool for monitoring pneumatic conveying in horizontal ducts. Power sp ectra of solids concentration fluctuations obtained from single-plane ECT d ata were used to identify the various flow regimes, and these were confirme d through visual observation. From single-plane ECT data, the instantaneous and time-averaged distributions of particle concentration over the cross s ection of the conveying pipe have been determined in various flow regimes. Propagation velocities of patterns were evaluated from cross correlation of twin-plane ECT data. The solids mass flow rate, determined independently b y load cell measurements, was found to be roughly proportional to the produ ct of the pattern velocity, the particle density, and the average solids ho ldup in the pipe, and the proportionality factor depended on the material b eing transported through the pipe. In our experiments involving flows past a 90 degrees smooth bend, ECT was able to detect significant temporal and s patial nonuniformity in particle concentration in the postbend region.