Experimental study of parameters which influence the energy minimum in horizontal gas–solid conveying

Optimization of pneumatic conveying may be achieved by a reduction of energy consumption by working with the lowest velocities. Based on an experimental approach, our study presents, for various products, the influence of several parameters (diameter, density and the shape of the particles) on the saltation velocity, i.e., the velocity corresponding to the lowest energy losses. The tests were carried out on a pneumatic transport test rig of industrial type composed of stainless pipeline of 80 mm inner diameter for a total length of 36 m. From the experimental results and the Zenz state diagram [F.A. Zenz, Two-phase fluid–solid flow, Ind. Eng. Chem., 41 (12) (1949) 2801–2806.], we analyze the variations of the saltation Froude number according to the solids loading ratio. These results enable us to establish a new correlation, which scans a broad spectrum of solids loading ratio.