Process for separating components of a polymer-monomer mixture obtained by high-pressure polymerization of ethylenically unsaturated monomers

A process for preparing ethylene homopolymers or copolymers comprising polymerizing ethylenically unsaturated monomers in the presence of free-radical polymerization initiators at temperatures from 100° C. to 350° C. and pressures in the range of from 110 MPa to 500 MPa in a polymerization reactor, the process comprising a process for separating a produced polymer-monomer mixture comprising polymeric components and gaseous components into a liquid fraction and a gaseous fraction, the process comprising the steps of:

• (v) introducing the polymer-monomer mixture into a separation vessel;
• (vi) separating the polymer-monomer mixture at a pressure of from 0.12 MPa to 0.6 MPa and a temperature of from 120° C. to 300° C. into a gaseous fraction and a liquid fraction;
• (vii) withdrawing the gaseous fraction from the top of the separation vessel;
• and
• (viii) withdrawing the liquid fraction from the bottom of the separation vessel,
• wherein the polymeric components of the mixture are produced by high-pressure polymerization of ethylenically unsaturated monomers in the presence of at least one free-radical polymerization initiator,
• and wherein
• a) the separation vessel has a vertically arranged cylindrical shape with a ratio of length to diameter L/D of from 0.6 to 10;
• b) the separation vessel is equipped with an inlet pipe capable of introducing the polymer-monomer mixture into the separation vessel;
• c) the inlet pipe extends vertically from the top of the separation vessel into the separation vessel;
• and
• d) the ratio of the inner diameter of the inlet pipe at its lower end and the inner diameter of the separating vessel in its cylindrical part is in the range of from 0.15 to 0.4.