Abstract
Plug flow of polyethylene pellets was studied in a 50 mm i.d horizontal pipe. The evolution of plug length and velocity along the pipe was deduced from relationships based on mass balances at the front and back of the plug.
The average pressure profile along the pipe was analysed with the help of the Ergun equation which governs interstitial gas flow in the plugs. In the case of low pressure gradients, it was demonstrated that the ratio of the plug length over void length, Lb/Lv , is constant along the pipe. How this ratio is correlated with gas flowrate was established through solids hold-up measurements.
