The Fluidized Bed reactor is a Vertical Pressure Vessel with a total Height of up to 40 m. A Fluidized Bed of Polymer Particles in Gaseous Ethylene is maintained by a Recycle Compressor. The Ethylene Recycling Gas enters the Reactor through a Distributor Plate at the bottom to achieve an even Gas Flow over the entire Cross-Section and to hold the Particles when the Gas Flow is turned off. In the characteristically conical upper part of the Reactor, the Gas Velocity decreases with the increasing Diameter of the Reactor to keep the Particles in the Fluidized Bed. The Gas leaves the Reactor at the top. The Reaction Temperature is 80 to 105 °C and the Reaction Pressure of 0.7 to 2 MPa is controlled by the Ethylene Feed Compressor. Polymer and Gas are extracted from the Fluidized Bed by Valves at the Bottom Section of the Reactor and expanded to a lower Pressure of approx. 0.15 MPa in a Degassing Vessel to separate Polymer Particles from Monomers.

Source: European Commission, European IPPC Bureau, Aug 2007, Reference Document on Best Available Techniques in the Production of Polymers.