Wear Mechanisms in Pneumatic Conveying of Sand and Analysis of Predictive Model for Pipeline Thickness Loss

Pneumatic conveying is a process of transportation of powder and granular materials through pipelines using high pressure gas. It is a frequently used method of material transport particularly for in-plant transport over relatively short distances, although long distance pipelines are becoming more common with technological advancements in this area. The major advantages of the system are the degree of flexibility it offers in terms of pipeline routing, dust minimization within the factory environment as well as automation. A large percentage of industrial systems are traditionally dilute phase system, which use relatively large amounts of air that lead to high particle velocities. Dense phase systems are designed to operate at relatively low velocity regimes which reduced the wear to some extent. Yet the problem of wear remains a major issue with these conveying systems. Service life of a pneumatic conveying system is dictated primarily by the wear in pipelines and bends due to the interactions between the particles and the surfaces. Depending on the conveying conditions or modes of flow, wear mechanism can be abrasive or erosive or a combination of both. The locations of the high wear areas also varies, depending on the ratio of the solids mass flow rate and the air velocity along the pipeline. Wear tests have been conducted using sand through a 50 mm diameter, 25 m pipeline fitted with a short radius bend to study the wear mechanisms associated within the critical wear area of the pipeline. The pipeline thickness loss has also been monitored using an ultra sonic thickness gage to generate the wear profile inside the pipeline. Surface analysis has been conducted using a scanning electron microscope to determine the associated wear mechanisms in the area. Finally, experimental results have been compared with the output of an energy based predictive model and the associated variations have been discussed.