An olefin polymerization process and apparatus wherein a fluid slurry comprising
monomer, diluent and catalyst is circulated in a continuous loop reactor by two
or more pumps. The process and apparatus allow operating the reaction at significantly
higher solids content in the circulating fluid slurry. In a preferred embodiment,
the fluid slurry is circulated by two impellers arranged so that the downstream
impeller benefits from the rotational energy imparted by the upstream impeller.
An olefin polymerization process operating at higher reactor solids by virtue of
more aggressive circulation has improved efficiencies, particularly in larger-volume reactors.