Abstract: The invention relates to a process for the preparation of a multimodal polyolefin polymer in a first polymerization reactor and a second polymerization reactor connected in series, wherein a first polyolefin polymer is prepared in the first polymerization reactor in suspension in the presence of hydrogen and a second polyolefin polymer is prepared in the second polymerization reactor in the presence of a lower concentration of hydrogen than in the first polymerization reactor, the process comprising: a) withdrawing a suspension of solid polyolefin particles in a suspension medium from the first polymerization reactor, wherein the suspension medium comprises hydrogen and a hydrocarbon mixture having an initial boiling point of at least 50° C. and a final boiling point of at most 120° C.; b) feeding the suspension to a flash drum having a pressure controlled by a vacuum pump, wherein the pressure of the flash drum is less than 0.

Abstract: The invention relates to a process for the preparation of an ethylene-based polymer, the process comprising: a) suspension polymerizing ethylene and an optional comonomer to obtain a suspension (11) comprising the ethylene-based polymer and wax in a suspension medium comprising a diluent, b) separating the ethylene-based polymer (13) from the suspension (11) to obtain a liquid stream (12) comprising the diluent and the wax, c) feeding at least part of the liquid stream (25) to a forced circulation reboiler (Q) for separating the diluent and the wax to obtain an evaporated stream (27) comprising the diluent, wherein the evaporated stream (27) is recycled to step a).

Abstract: The invention relates to a process for the preparation of a multimodal polyolefin polymer in a first polymerization reactor and a second polymerization reactor connected in series, wherein a first polyolefin polymer is prepared in the first polymerization reactor in suspension in the presence of hydrogen and a second polyolefin polymer is prepared in the second polymerization reactor in the presence of a lower concentration of hydrogen than in the first polymerization reactor, the process comprising: a) withdrawing a suspension of solid polyolefin particles in a suspension medium from the first polymerization reactor, wherein the suspension medium comprises hydrogen and a hydrocarbon mixture having an initial boiling point of at least 50° C. and a final boiling point of at most 120° C.; b) feeding the suspension to a flash drum having a pressure controlled by a vacuum pump, wherein the pressure of the flash drum is less than 0.