Modeling minimum transport boundary for pneumatic conveying of powders

Accurate prediction of blockage conditions or the minimum transport boundary is essential for the reliable design and operation of a pneumatic powder conveying system. Many existing empirical models for minimum transport boundary do not consider essential powder properties and operating conditions, such as loose poured bulk density, particle size, and air density. Based on the conveying results of 13 different powders, this paper has developed a new empirical model for the minimum transport boundary. The model includes a Froude number based on particle size and bulk density and a dimensionless gas density term, which makes the model inherently adaptable to variations in powder properties and operating conditions. Results of validation show that the new model provides a significantly improved prediction of minimum Froude Number (in the range of 7 to 13% relative error only) compared to the existing models, which provided relative errors in the range of 19 to 67%.