Solids flow imaging and attrition studies in a pneumatic conveyor

This work describes the first application of a non-invasive capacitance tomographic technique to monitoring the behaviour of industrial-scale pneumatic conveyors. Dynamic images of the solids distribution within a pipe have captured the movement of slugs in dense-phase solids conveying, and the presence of saltation in dilute-phase conveying. It has also been possible to acquire images downstream of a pipe bend and to use this information to establish a suitable location for obtaining a representative sample of a material stream. The information provided by cross-sectional images facilitates the validation of theoretical models and ultimately will allow improved design as the sensitivity and resolution of the technique are enhanced. A study of particle (sea salt) attrition is reported using a conveying line 32 m in length. It is demonstrated that particle breakage can be described as a function of the conveying velocity and solids-gas loading factor. Particle breakage is described in terms of the mass-specific surface area, and is seen to increase with conveying velocity. Particle breakage rates are found to be inversely related to the solids loading factor.