Dr Aleksej Lavrinec

Within the field of pneumatic conveying horizontal (Plug-1) and vertical plug flows have been investigated only in the context of cohesive fine powders. This paper considers a series of experiments using fuzzy cottonseeds, which greatly differ in particle and bulk properties from fine powders, to investigate plug formation. In this study, several possible dense phase behaviours were observed, which were consistent in vertical and horizontal orientations and mostly influenced by the batch size of feeding into the rig due to its influence on particle arrangement. Particle arrangement at the plug base or rear was found to be critical for achieving stable plugs, with a requirement of the rear or base batch having the length of more or equal to pipe diameter. This work sheds light on the general features and mechanisms governing horizontal and vertical plug formation.

This study used a 3D coupled CFD¿DEM model to assess how slugs tend towards steady state in single slug horizontal pneumatic conveying. Initial slug length, inlet velocity and initial stationary layer fractions were systematically varied for a total of 72 simulations. Previously made observation that slugs tend towards a steady state was confirmed via a theoretical derivation. The derivation shows that slugs move towards their steady state lengths exponentially. This allowed for a calculation of a characteristic time scale which is a measure of how quickly a slug tends towards the steady state. The theoretical estimate which is a function of slug porosity, steady length, velocity and stationary layer fraction has good agreement with simulated results. A link between steady slug length and solids loading ratio was also shown.

This paper presents the results of using an inertial measurement unit (IMU) to study various dynamic relationships in horizontal slug flow pneumatic conveying. The accuracy of the IMU was assessed and compared to particle image velocimetry (PIV) and once good agreement was confirmed it was used to investigate various aspects of slug flow. Relative movement between core particles and slugs tails and heads was assessed using relative pressures and quantified times spent in a slug. It was found that the propagation of particles backwards through a slug is relatively constant. Pressure-velocity relationship was observed that was theorised to be related to variations in stationary layer ahead of the slugs. Observations of further nuanced features of slug motion are also included to demonstrate the capabilities of IMUs in capturing the many dynamic aspects of the flow.