Slurry phase polymerisation process

US8202951B2 · kind B2 · utility

Assignee

• INEOS MANUFACTURING BELGIUM NV · BE

Inventors

• Benoit Koch · Hannut, BE
• Daniel Marissal · Braine-le-Comte, BE
• Marc Parisel · Vilvoorde, BE
• Brent R. Walworth · Sint-Niklaas, BE

Key dates

• Filing date: Aug 29, 2008
• Grant date: Jun 19, 2012
• Expiry date: Feb 6, 2029

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C08F210/16
• WIPO field: Macromolecular chemistry, polymers
• WIPO sector: Chemistry

Abstract

Process for producing a multimodal polyethylene in at least two reactors connected in series, in which 20-80 wt % of a first polymer is made in suspension in a first reactor and 80-20 wt % of a second polymer is made in suspension in a second reactor in the presence of the first polymer, and a stream or slurry containing the resulting polymer is withdrawn from the second reactor and transferred to a flash tank operating at a pressure and temperature such that at least 50 mol % of the liquid component of the slurry, or the non-polymer component of the stream entering the flash tank, is withdrawn from the flash tank as a vapour, wherein the concentration in the stream or slurry entering the flash tank of components having a molecular weight below 50 g/mol, Clights (mol %), satisfies the equation Clights<7+0.07(40−Tc)+4.4(Pc−0.8)−7(CH2/CEt) where Tc and Pc are respectively the temperature (in ° C.) and pressure (MPa g) at the location where the vapour withdrawn from the flash tank is condensed, and CH2 and CEt are the molar concentrations in the flash tank of hydrogen and ethylene respectively.