US 12,240,923 B2
Suspension process for preparing ethylene polymers comprising work-up of the suspension medium
Peter Rohrbach, Hofheim/Ts. (DE); Jürgen Perzlmeier, Neustadt/Donau (DE); Elke Damm, Bad Vilbel (DE); and Harald Prang, Erftstadt (DE)
Assigned to Basell Polyolefine GmbH, Wesseling (DE)
Appl. No. 17/614,708
Filed by Basell Polyolefine GmbH, Wesseling (DE)
PCT Filed May 28, 2020, PCT No. PCT/EP2020/064792
§ 371(c)(1), (2) Date Nov. 29, 2021,
PCT Pub. No. WO2020/239885, PCT Pub. Date Dec. 3, 2020.
Claims priority of application No. 19177333 (EP), filed on May 29, 2019.
Prior Publication US 2022/0220233 A1, Jul. 14, 2022
Int. Cl. C08F 2/00 (2006.01); B01D 3/14 (2006.01); B01D 3/38 (2006.01); B01D 17/04 (2006.01); C08F 10/02 (2006.01); C08F 110/00 (2006.01); C08F 210/16 (2006.01)
CPC C08F 10/02 (2013.01) [B01D 3/143 (2013.01); B01D 3/38 (2013.01); B01D 17/045 (2013.01); C08F 2/00 (2013.01)] 19 Claims
OG exemplary drawing
 
1. A process for preparing an ethylene polymer in a suspension polymerization in a polymerization reactor or a series of polymerization reactors comprising the steps of:
polymerizing ethylene or copolymerizing ethylene and one or more C3-C12-1-alkenes at temperatures of from 40 to 150° C. and pressures of from 0.1 to 20 MPa in the presence of a polymerization catalyst and forming a suspension of ethylene polymer particles in a suspension medium comprising a hydrocarbon diluent,
transferring the suspension of ethylene polymer particles into a solid-liquid separator,
wherein the suspension is separated into wet ethylene polymer particles and mother liquor,
transferring a first part of the mother liquor into a work-up section comprising an evaporator for producing a wax-depleted portion of the mother liquor, a diluent distillation unit for producing isolated diluent from the wax-depleted portion of the mother liquor, and a wax removal unit operated by direct steam distillation for removing wax from a hydrocarbon wax solution, wherein the wax removal unit produces a gaseous hydrocarbon and steam mixture which is condensed and then separated, within a first liquid-liquid separator, into an aqueous phase and a hydrocarbon phase, and
recycling a first part of the isolated diluent produced in the diluent distillation unit to the polymerization reactor or the series of polymerization reactors,
wherein a first part of the hydrocarbon phase obtained in the first liquid-liquid separator is transferred to the diluent distillation unit without passing the evaporator for producing the wax-depleted portion of the mother liquor.