Abstract: An olefin polymerization apparatus is disclosed wherein monomer, diluent and catalyst are circulated in a continuous pipe loop reactor and an intermediate product slurry is recovered by a continuous product take off means. The intermediate product slurry is passed to a hydrocyclone to stratify polymer particles based on size. A slurry containing predominantly fines is withdrawn overhead and returned to the reaction zone. The slurry containing predominantly fines is preferably returned to the polymerization zone just upstream of the circulation pump and in a preferred embodiment this pressure differential is the sole driving force for the hydrocyclone separation. In another embodiment the product slurry from the bottom of the hydrocyclone is passed to a solids-liquid separator where the solids settle to the bottom and essentially polymer free diluent is recycled. In another embodiment, the intermediate product slurry is withdrawn via a conical settling leg.

Abstract: An olefin polymerization apparatus is disclosed wherein monomer, diluent and catalyst are circulated in a continuous pipe loop reactor and an intermediate product slurry is recovered by a continuous product take off means. The intermediate product slurry is passed to a hydrocyclone to stratify polymer particles based on size. A slurry containing predominantly fines is withdrawn overhead and returned to the reaction zone. The slurry containing predominantly fines is preferably returned to the polymerization zone just upstream of the circulation pump and in a preferred embodiment this pressure differential is the sole driving force for the hydrocyclone separation. In another embodiment the product slurry from the bottom of the hydrocyclone is passed to a solids-liquid separator where the solids settle to the bottom and essentially polymer free diluent is recycled. In another embodiment, the intermediate product slurry is withdrawn via a conical settling leg.