Hydrodynamic model for the flow of granular solids in the S-valve

This article proposes a phenomenological model to predict the discharge of granular solids (group D in the Geldart classification) through a valve known as the S-valve (or spitting valve), which controls the flow of solids with the injection of a gas. The model predicts the flow of solids as a function of the density of the solid (ρs), the friction coefficient (fs), the void fraction (ε), the gas flow (Q), the valve diameter (Dv), the pressure (P), and the spitting factor (SF). The friction coefficient, fs, and the void fraction, ε, were estimated based on the surface velocity of the aeration gas using empirical relationships that were integrated into the model. The solids used were rice, lentils, and green coffee beans. The deviation from the model was ± 3% for rice and lentil grains and ± 2% for green coffee for a range of operation between 0.4 and 0.7 MPa.

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► A novel non-mechanical valve (the S-valve) to control flow of granular materials.
► We propose a phenomenological model to predict the discharge of granular solids.
► Comparison between observed results and those predicted by the model is acceptable.