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

Abstract

The impacts of particle diameter (dp), particle density (ρp) and particle sphericity (φ) on the minimum pickup velocity (Upu) 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 dp (i.e., binary-size), (ii) only ρp (i.e., binary-density), and (iii) both dp and ρp (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, Upu, was experimentally determined by the weight loss method and also derived using a force balance model developed here. The key results were: (1) dp exerts a more dominant influence on Upu than ρp; (2) particle sphericity (φ) has a non-negligible impact on Upu; and (3) a drag and frictional force balance analysis accounting for particle sphericity gives reasonable predictions of Upu, which in turn provides a mechanistic insight on Upu.