A COMPARISON OF PARTICLE WEAR IN PNEUMATIC TRANSPORT

Abstract

Flow regimes and particle degradation in pneumatic transport depend on the operating conditions, granular material properties, and dynamic behavior of the system in a very complex way. In this work, an experimental study was carried out using a blow tank system, which was operated under several phase regimes with the help of a secondary air line. Flow maps were constructed to predict horizontal flow patterns under conditions that ranged from plug to dilute phase flow, using two test materials: sodium and potassium nitrate prills. They have identical particle size distributions, but very different strength properties, allowing a comparative study of the particle degradation (breakage and dusting) of soft and hard materials in a wide range of flow conditions, identified as plug-, slug-, dune-, and dilute-phase regimes. The results demonstrated clear advantages in dust reduction for dense-phase conveying compared to dilute phase; however, particle breakage rates were similar in both types of systems. Dusting and breakage were the dominant wear processes for the softer material (sodium nitrate), while breakage, to a lesser extent, prevailed for the case of the brittle material (potassium nitrate).