Technology

Propylene, ethylene and any other required comonomers are fed into the reactor(s). Hydrogen is added to control the molecular weight. Polymerization conditions (temperature, pressure and reactant concentrations) are set by the polymer grade to be produced. The reaction itself is exothermic. Reactor cooling is achieved by evaporation of liquefied reactor gas, which is injected into the reactor. Flash evaporation of the liquid in the polymer bed ensures efficient heat removal.

The polymer (polypropylene) powder is discharged from the reactor(s) and separated from the gas in a discharge cyclone at atmospheric pressure. Any unreacted monomer separated from the powder is compressed and either recycled or returned to the upstream olefins unit for recovery.

The final degassing of the polymer is done in a purge silo by flushing with Nitrogen. The purge offgas is sent to a recovery system.

Finally, the powder is converted into pellets that incorporate a full range of well-dispersed Additives.

Source: Lummus Technology, Process Technologies, Petrochemicals.