The LDPE process consists in five operations :
– The compression of gas : Gaseous ethylene is supplied and melted with a part of unreacted gas from the process in oreder to be compress in the first reactor.This new compressed gas is melted again with unreacted gas and compress in the second compressor.
– The polymerization : An initiator (organic peroxide) is added to the second compressed gas into the reactor and the materials are mixed inside the reactor through stirrer . Polymerization is obtained in the reactor at a certain pressure and temperature.
– The separation of gas : The unreacted gas is then separated by 3 levels of separators. Those unreacted gas will be injected before the compressor, notice than a part will be exclude from the process.
– The extrusion : Once the unreacted gas is removed, the polymers can be extruded and pelletized.
– The storage and packaging : The pellets are dried through a dryer and classified pellets by pellet size. The degassing is done by hot air injection.
The HDPE process consists of :
– Polymerization : Ethylene monomers are polymerized in solvent together with catalyst, hydrogen and comonomer. The polymerization heat is cooled through external circulation heat exchanger. The reacted slurry is transferred to the separation/drying process.
– Separation/Drying : Slurry is transferred to a high-speed centrifuge from which it is separated into solvent and wet powders. The separated solvent is supplied to the reactor and some solvents are recycled in the process through refining. Wet powders are transferred to the powder dryer and dried.
– Transfer/Extrusion : The wet powders are dried in the powder dryer by evaporating the solvent with high-temperature nitrogen and steam. The evaporated solvent is recovered by the scrubber. The dried powders are transferred to the extrusion process where they are melted and pelletized in the extruder. Then they are transferred to the storage silo.
– Storage & Packaging : The products transferred to the pellet silo are cooled by air and homogenized.
