HDPE Pellets: Ethylene Polymerised in a Fluidised Bed

High-density polyethylene is made at low pressure on a Ziegler catalyst (a titanium halide with an aluminium compound). In the gas-phase process, ethylene flows up through a fluidised bed of fine catalyst at 85–100 °C and 20 bar and grows into polymer powder, which is melted and cut into pellets. The picture: our diagram of the bed reactor and extruder.