Ultrasound imaging in large gas and liquid processing vessels

A programme of work is described investigating the application of acoustic imaging techniques to large process vessels containing gas-liquid and liquid-liquid features. A 1 m 2 hydrophone array suspended in a large tank of water was successfully able to discriminate temperature and simulated vapour plumes with a time resolution of half a second using time-of-flight or attenuation information by an iterative analytical technique. The subsequent application to a 0.6 m diameter model liquid-liquid extraction column highlighted drawbacks such as the cost and obtrusiveness of suitable transducers, and it became clear that further increases in scale would become increasingly difficult to image, at least in real time. However, ultrasound could be used diagnostically in such columns in a non-tomographic way, for instance by using neural networks to recognise normal and fault conditions in the attenuation pattern along a single chord.