Experimental and numerical studies on dense-phase pneumatic conveying of spraying material in venturi

In the present work, the computational fluid dynamics (CFD)–discrete element method (DEM) coupling approach and the experimental method were performed to study the flow characteristic of the spraying material in a venturi for the different air supplementary velocity and moisture content of the spraying material. The model was implemented in a two-way coupling with commercial software DEM package EDEM 2.5® and CFD package Fluent 14.5®, so that the results could be replicated in a standard and user-friendly framework. Particle concentration, velocity and gas pressure drop were systematically compared among different gas supplementary velocities, and the gas pressure drop was found to decrease first and then increase with the increase of the supplementary gas velocity, and the critical wind speed for this spraying material was finally reached. The pressure drop was found to decrease first and then increase with the increasing of the moisture content of the spraying material. The particles were agglomerated and lose their fluidity due to the presence of moisture. Coefficient of variation of the pressure at the outlet of the venturi was presented to study the flow stability, and the result revealed that the fluid flow stability increased with the decrease of the coefficient of variation. When the inlet gas velocity was above 30 m/s, the solid-gas ratio would make a slight impact on the flow stability, and the moisture content m = 15% was the optimum moisture content for pneumatic conveying of this spraying material.