Patent ID: 6924340

Claim:
A process for the preparation of a polyolefin polymer, said process comprising: a) polymerizing at least one olefin monomer in the presence of hydrogen in a prior slurry reactor employing light solvent as a slurry medium to form a first polyolefin polymer of a first molecular weight; b) removing said first polyolefin polymer from said prior slurry reactor as a hydrogen-containing polymer slurry in light solvent and introducing said hydrogen-containing polymer slurry into a first flash drum; c) flashing away light solvent and hydrogen in said first flash drum to provide a polymer-enriched and hydrogen-depleted first flash drum slurry; d) adding to said first flash drum slurry additional light solvent; e) introducing said first flash drum slurry into a second flash drum; f) flashing away further light solvent and further hydrogen to form a second flash drum slurry; and g) introducing said second flash drum slurry into a subsequent slurry reactor employing a low concentration of hydrogen, and recovering a polyolefin polymer therefrom, wherein the hydrogen mass flow from the second flash drum slurry is less than a fresh hydrogen mass flow feed to the subsequent reactor by a factor of at least 10.