Theoretical Modelling of Airslides for Fine Powder Transporting

Airslides are widely used in industries to transport fine powder in a dense phase under gravity. Currently, the design of airslides is mainly based on empirical methods without considering the properties of fine powder and the conditions of fluidization. This paper aims at theoretically analyzing the flow behavior of fluidized fine powder within an airslide under both vent and non-vent conditions. Specifically, constitutive equations describing the conservation principles and mechanics of the fluidized fine powder flow are established using a continuum approach. Impressible approximation is adopted to solve the constitutive equations, from which six airslide transporting models are developed dependent on different fluidization conditions and ventilation. Accordingly, a series of experiments with sand and flyash is conducted based on an airslide test rig, from which the parameters of the fluidized fine powder flow related to the transporting models are determined. The material bed heights of the fluidized flow predicted theoretically are compared with those obtained from the experiments to validate the developed transporting models. The results reveal that good agreement can be achieved, indicating that the developed transporting models are capable of analyzing the flow behavior of airslides.