Advanced technology in spray-dried ceramic slip conveying: Design, process simulation and test facility

Spray-dried ceramic slip (hereinafter “atomized slip”) conveying is mainly carried out by belt conveyors. The bulk solid is picked up from the spray dryer bottom and then covers long distances, crossing the working environment and rising up to feed final stocking silos. Conveyor belts, without specific powder confinement devices, spread out fine particles, causing dust pollution and generating risk for workers' health (silicosis). Atomized slip pneumatic transport solves a problem of dust pollution caused by atomized slip belt conveying. However, atomized slip pneumatic conveying can be suitable only if some fluid-dynamical and thermo-hygrometric parameters are effectively under control. In fact, both solid maximum conveying velocity and speed gradient (i.e. the variation of solid velocity, in m/s, per meter of pipe length) need to be limited to guarantee product integrity and quality. Moreover, atomized slip humidity must be kept within a range (4–7% in weight) to give some specific characteristics to the final product. So, compressed air humidity, pressure and temperature need to be controlled all along the pipeline to avoid relevant atomized slip humidification or drying. The paper describes the design process and realization of an atomized slip pneumatic conveying test facility carried out to confirm fluid-dynamical conveying parameters. A finite element software simulator (TPSimWin) was used to evaluate and control atomized slip velocity, speed gradient, humidity and temperature along the pipeline.