Spheripol Process
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This process is based on Himont (now Bassel) technology uSing supported catalysts. Polymerization takes place 70C and 4 MPa in liquid propene circulating round one or more loop reactors. A single axial flow agitator in each loop maintains high flow rates to ensure good heat transfer to the water-cooled jackets. Typically the PP concentration is 40 wt%.
Spheripol Process
a) Loop reactors; b) Primary cyclone; c) Copolymer fluidized bed; d) Secondary and copolymer cyclone;
e) Deactivation; f) Purging
Continuously metered catalyst, triethyaluminum, and a Lewis base stereoregulator such as dialkyldimethoxysilane are fed into the reactor to maintain polymerization and stereocontrol The initial few seconds of polymerization with a new high-activity catalyst particle are quite critical to secure good performance For this reason, some processes have prepolymerization stage in which the catalyst components react at lower temperature and monomer concentration.
The prepolymerized catalyst is then fed into the loop reactor. Mean residence time is 1-2 h. two loop reactors can be operated in series to narrow residence time distribution, modify the polymer, and increase output.
A continuous stream of polymer slurry discharges through a heated zone for the first stage of pressure let down on cyclone (b). For homopolymers, this connects directly to the secondary cyclone (d), bypassing the copolymerization unit. Untreated propene flashes off from the first cyclone and is condensed with cooling water and recycled to the reactor. A compressor is required for gas from cyclone (d). Polymer powder from the cyclone is fed into vessel (e) for deactivation with steam and additives. Residual moisture and volatiles are removed by a hot nitrogen purge vessel (f) before conveying polymer to storage silos for finishing as stabilized powder or extruded pellets.
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