Impact of particle diameter, density and sphericity on minimum pickup velocity of binary mixtures in gas-solid pneumatic conveying

The impacts of particle diameter (d(p)), particle density (rho(p)) and particle sphericity (phi) on the minimum pickup velocity (U-pu) of binary mixtures of Geldart group B particles were investigated. Three types of binary mixtures were tested, whereby the two constituents vary in (i) only d(p) (i.e., binary-size), (ii) only rho(p) (i.e., binary density), and (iii) both d(p) and rho(p) (i.e., binary-size-density). Notably, there is a lack of data on the pickup characteristics of the latter two types of binary mixtures, although behavioral differences are acknowledged. The minimum pickup velocity, U-pu, was experimentally determined by the weight loss method and also derived using a force balance model developed here. The key results were: (1) d(p) exerts a more dominant influence on U-pu than rho(p); (2) particle sphericity (phi) has a non-negligible impact on U-pu; and (3) a drag and frictional force balance analysis accounting for particle sphericity gives reasonable predictions of U-pu, which in turn provides a mechanistic insight on U-pu. (C) 2016 Elsevier B.V. All rights reserved.