Abstract: A process for preparing ethylene polymers including the step of polymerizing ethylene or copolymerizing ethylene and one or more comonomers at a temperature from 100° C. to 350° C. and a pressure of from 110 MPa to 350 MPa in a continuously operated tubular polymerization reactor, thereby yielding a reaction mixture, wherein the tubular polymerization reactor has a reactor cooling jacket for removing the heat of the reaction and a pressure control valve, the reaction mixture leaves the reactor through the pressure control valve, the reaction mixture then passes a post-reactor cooler equipped with a post-reactor cooling jacket, the reactor cooling jacket is provided with a reactor coolant having an inlet temperature and the post-reactor cooling jacket is provided with a post-reactor coolant having an inlet temperature, and the inlet temperature of the post-reactor coolant is independently controlled from the inlet temperature of the reactant coolant.

Abstract: Method for the preparation of dried polymer pellets in a facility having a dryer with a first chamber and a mechanical agitator, and the facility further having a degassing silo with a second chamber, the method includes the steps of guiding a drying gas flow made from or containing a first gas mixture for drying wet polymer pellets into the first chamber, transferring the dried polymer pellets into the second chamber, guiding a second gas mixture for degassing the dried polymer pellets into the second chamber thereby transforming the second gas mixture into a third gas mixture and guiding a portion of the third gas mixture into the first chamber; and process for manufacturing LDPE pellets.

Abstract: A high-pressure polymerization system having a) a polymerization reactor and b) a reactor blow down system having b1) a reactor blow down vessel, having a circular design over a major portion P having a L/D-ratio in the range from 1.75 to 10.0 and containing an aqueous quenching medium, b2) a release line connecting the polymerization reactor with the reactor blow down vessel and having an outlet located above a maximum level for the aqueous quenching medium, b3) a first emergency valve in the release line to open and close fluid communication between the polymerization reactor and the reactor blow down system, and wherein the release line outlet has a joining piece having an angle (a) between the central axis and a tangent at the reactor blow down vessel in the range from 5° to 70° and the reactor blow down vessel has a vent stack containing a constricted section.

Abstract: A process for polymerizing ethylene in a high-pressure polymerization system having a continuously operated polymerization reactor and a reactor blow down system having an emergency valve, a reactor blow down vessel containing an aqueous medium and a reactor blow down dump vessel, wherein the process includes the steps of monitoring the polymerization system for a disturbance, opening the emergency valve when a disturbance occurs to allow the content of the polymerization system to expand into the reactor blow down vessel, contacting the content of the polymerization system in the reactor blow down vessel with the aqueous medium to obtain an aqueous polymer slurry, separating the polymer slurry and gaseous components, and transferring the polymer slurry to the reactor blow down dump vessel.

Abstract: A process for the preparation of ethylene homopolymers or copolymers in a facility having a high-pressure tubular reactor and a preheater, wherein a reaction fluid introduced into the reactor at a reactor inlet is heated in the preheater and the average velocity of the reaction fluid in the preheater is lower than the average velocity of the reaction fluid in the tubular reactor and the ratio of the average velocity in the tubular reactor to the average velocity of the reaction fluid in the preheater is in the range from 1.5 to 5.

Abstract: Method for the preparation of dried polymer pellets in a facility having a dryer with a first chamber and a mechanical agitator, and the facility further having a degassing silo with a second chamber, the method includes the steps of guiding a drying gas flow made from or containing a first gas mixture for drying wet polymer pellets into the first chamber, transferring the dried polymer pellets into the second chamber, guiding a second gas mixture for degassing the dried polymer pellets into the second chamber thereby transforming the second gas mixture into a third gas mixture and guiding a portion of the third gas mixture into the first chamber; and process for manufacturing LDPE pellets.

Abstract: A process for the preparation of ethylene homopolymers or copolymers in a facility having a high-pressure tubular reactor and a preheater, wherein a reaction fluid introduced into the reactor at a reactor inlet is heated in the preheater and the average velocity of the reaction fluid in the preheater is lower than the average velocity of the reaction fluid in the tubular reactor and the ratio of the average velocity in the tubular reactor to the average velocity of the reaction fluid in the preheater is in the range from 1.5 to 5.

Abstract: A process for polymerizing ethylene to obtain an ethylene-based polymer in a plant, wherein the plant includes a reactor in fluid communication with a recycle connection, wherein the process includes a polymerization phase, a partial shutdown phase, and the steps of reducing the pressure in the reactor for entering into the partial shutdown phase from the polymerization phase; and increasing the pressure in the reactor for exiting from the partial shutdown phase and re-entering the polymerization phase.

Abstract: A process for polymerizing ethylene to obtain an ethylene-based polymer in a plant, wherein the plant includes a reactor in fluid communication with a recycle connection, wherein the process includes a polymerization phase, a partial shutdown phase, and the steps of reducing the pressure in the reactor for entering into the partial shutdown phase from the polymerization phase; and increasing the pressure in the reactor for exiting from the partial shutdown phase and re-entering the polymerization phase.

Abstract: Process for copolymerizing ethylene and esters of vinyl alcohol in the presence of free-radical polymerization initiators at pressures in the range of from 110 MPa to 500 MPa and temperatures in the range of from 100° C. to 350° C. in a continuously operated polymerization apparatus comprising a polymerization reactor and one or more compressors, which compress the monomer mixture fed to the polymerization reactor to the polymerization pressure, wherein the monomer mixture is compressed by a sequence of compression stages in which the compressed gas mixture is cooled after each compression stage and the fraction of the monomer mixture, which is liquid after this cooling, is separated off and returned to the polymerization apparatus in liquid form, and wherein at least a part of the liquid fractions obtained after compressing the monomer mixture in the respective compression stage to a pressure of from 0.2 MPa to 10 MPa is purified before being returned to the polymerization process.

Abstract: A process for separating polymeric and gaseous components of a 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. in a separation vessel is provided. The separation vessel has a vertically arranged cylindrical shape with a ratio of length to diameter L/D of from 0.6 to 10 and an inlet pipe capable of introducing the polymer-monomer mixture into the separation vessel which the inlet pipe extends vertically from the top of the separation vessel into the separation vessel. Further a process for preparing ethylene homopolymers or copolymers from 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 comprising such a process for separating a polymer-monomer mixture is provided.

Abstract: A process for separating polymeric and gaseous components of a 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. in a separation vessel is provided. The separation vessel has a vertically arranged cylindrical shape with a ratio of length to diameter L/D of from 0.6 to 10 and an inlet pipe capable of introducing the polymer-monomer mixture into the separation vessel which the inlet pipe extends vertically from the top of the separation vessel into the separation vessel. Further a process for preparing ethylene homopolymers or copolymers from 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 comprising such a process for separating a polymer-monomer mixture is provided.

Abstract: Process for copolymerizing ethylene and esters of vinyl alcohol in the presence of free-radical polymerization initiators at pressures in the range of from 110 MPa to 500 MPa and temperatures in the range of from 100° C. to 350° C. in a continuously operated polymerization apparatus comprising a polymerization reactor and one or more compressors, which compress the monomer mixture fed to the polymerization reactor to the polymerization pressure, wherein the monomer mixture is compressed by a sequence of compression stages in which the compressed gas mixture is cooled after each compression stage and the fraction of the monomer mixture, which is liquid after this cooling, is separated off and returned to the polymerization apparatus in liquid form, and wherein at least a part of the liquid fractions obtained after compressing the monomer mixture in the respective compression stage to a pressure of from 0.2 MPa to 10 MPa is purified before being returned to the polymerization process.