Pumping apparatus and process for slurry polymerization in loop reactors

Abstract

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.

Description

[0001] related application [0002] This application claims the benefit of US Provisional Patent Application No. 60 / 411,612, filed September 17, 2002 (the "'612 application") under 35 U.S.C. §119(e). The '612 application is incorporated herein by reference. technical field [0003] The present invention relates to slurry polymerization in a liquid medium. More specifically, the present invention relates to pumping apparatus and methods for large volume loop reactors for slurry polymerization. Background technique [0004] Polyolefins such as polyethylene and polypropylene can be prepared by polymerization in particle form (also known as slurry polymerization). In this technique, feed materials such as monomer and catalyst are fed into a loop reactor and a product slurry comprising polyolefin solid particles in a liquid medium is withdrawn or discharged from the reactor. [0005] In a loop polymerization operation, a fluid slurry is circulated through the loop reactor by o...

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