Development of an ultrasonic tomography system for application in pneumatic conveying

This paper details the development of a tomographic technique for imaging gas - solid flow distributions in pneumatic conveying pipelines. The technique utilizes ultrasonic transmission-mode measurements constrained to the megahertz region. Image reconstruction is performed by an efficient backprojection method implemented with standard graphics algorithms. Simulated reconstructions of dense and dilute distributions are presented. These results demonstrate the capabilities and limitations of the technique. Aspects of transducer array design are also addressed. An optimal arrangement for imaging dense phase flow distributions is derived and the characteristics of air-loaded and water-loaded, matched and unmatched peizoceramic transducers are evaluated. The validity of the technique is demonstrated using a low-frequency (72 kHz) system constructed with prototype fan-shaped-beam electrostatic transducers. Further development of the technique for practical application is discussed.