Remote monitoring of slug sequence and flow stability in Dense-Phase Pneumatic Conveying
In a wide variety of industrial applications, materials having diverse particle characteristics are pneumatically conveyed through enclosed pipelines. The main objective of pneumatic conveying is to transport reliably as much material as possible with minimal energy consumption. For abrasive bulk solids or fragile materials it is furthermore essential to maintain transportation velocities as low as possible to minimise damage to both the conveying system and the material. In dense phase flow, particles are transported in a non-suspended state. This type of flow is also known as plug flow. This flow regime consists of alternating sequences of dense material concentration (plug), followed by a section with no or very little material. In contrast to dilute phase flow, material velocities are comparably low in dense phase conveying, although higher mass transportation per time unit can be achieved. A stabile plug flow is characterised by a regular sequence of well shaped particle slugs with approximately the same lengths. Strong deviations from a periodical plug sequence and unstable material slugs are an indicator for conveying parameter maladjustment. For in-line monitoring of stability and sequence of material slugs in dense phase conveying, this paper presents two measurement principles. Both methods feature a non-invasive measurement technique from the outside of a closed conveyor pipe and are capable of performing quality inspection for the present material flow.