Abstract: A process for controlling a slurry phase (co-) polymerisation process in the presence of a polymerisation catalyst, which comprises maintaining the density SPAN of the polymer powder particles (defined as the absolute value of the density difference in g/cm3 between the average density of the polymer particles exiting the reactor with particle size above D90 and the average density of the material with particle size below D10) below 0.005, preferably below 0.003, more preferably below 0.0026, most preferably below 0.0023.

Abstract: Process for heating a polymer-containing stream being transferred from a polymerization reactor to a degassing vessel operating at a pressure between 6 bara and 12 bara. The process includes passing the stream through a heater having a transfer line for the stream and a device for heating the transfer line. The pressure drop in the heater is between 5% and 50% of the total pressure drop between the polymerization reactor and the entry to the degassing vessel. The pressure drop across the length of the heater is less than 0.5 barh per tonne of polymer, and the average Reynolds number across the cross-section of the stream at any point along the length of the transfer line of the heater is greater than 500,000, such that at least 90 mol% of the hydrocarbon fluids withdrawn from the polymerization reactor operation are vaporized before entry into the degassing vessel.

Abstract: Process for heating a polymer-containing stream being transferred from a polymerization reactor to a degassing vessel operating at a pressure between 6 bara and 12 bara. The process includes passing the stream through a heater comprising a transfer line for the stream and a device for heating the transfer line. The ratio of the stream velocity at the outlet of the heater to that at the inlet, Vo/Vi, is at least 1.1, typically between 1.2 and 4, and the total specific heat transfer area of the transfer line is at least 0.5 m2 per tonne/h of production of polymer. The pressure drop across the length of the heater is less than 0.5 bar per tonne/h of polymer, such that at least 90 mol % of the hydrocarbon fluids withdrawn from the polymerization reactor operation are vaporized before entry into the degassing vessel.

Abstract: A process comprising polymerising in a loop reactor an olefin monomer optionally together with an olefin commoner in the presence of a polymerisation catalyst in a diluent to produce a slurry comprising solid particulate olefin polymer and the diluent wherein the Fronde number is maintained at or below 20 is disclosed.

Abstract: A process comprising polymerizing an olefin monomer optionally together with an olefin comonomer in the presence of a polymerization catalyst in a diluent in a loop reactor which comprises at least 2 horizontal sections and at least 2 vertical sections to produce a slurry comprising solid particulate olefin polymer and the diluent wherein the Froude number in at least 20% of the length of the vertical sections of the reactor loop is less than 85% of the Froude number in at least 20% of the length of the horizontal sections of the loop is disclosed.

Abstract: Process for producing a multimodal polyethylene in at least two reactors connected in series, in which 20-80 wt % of a high molecular weight (HMW) polymer is made in suspension in a first reactor and 20-80 wt % of a low molecular weight (LMW) polymer is made in suspension in a second reactor, wherein the ratio of the average activity in the LMW reactor to the average activity in the HMW reactor is from 0.25 and 1.

Abstract: A process comprising polymerising in a loop reactor an olefin monomer optionally together with an olefin commoner in the presence of a polymerisation catalyst in a diluent to produce a slurry comprising solid particulate olefin polymer and the diluent wherein the Froude number is maintained at or below 20 is disclosed.

Abstract: A process comprising polymerising in a loop reactor of continuous tubular construction an olefin monomer optionally together with an olefin comonomer in the presence of a polymerisation catalyst in a diluent to produce a slurry comprising solid particulate olefin polymer and the diluent wherein the internal diameter of at least 50% of the total length of the reactor is at least 700 millimeters and the solids concentration in the reactor is at least 20 volume % is disclosed.

Abstract: Process for producing a multimodal polyethylene in at least two reactors connected in series, in which 20-80 wt % of a high molecular weight (HMW) polymer is made in suspension in a first reactor and 20-80 wt % of a low molecular weight (LMW) polymer is made in suspension in a second reactor in the presence of the HMW polymer, wherein the solids concentration in the second LMW reactor, defined as the mass of polymer divided by the total mass of slurry, is at least 35 wt %, most preferably between 45 wt % and 60 wt %, and/or the ratio of solids concentration in the first reactor to that in the second reactor is maintained at less than 1.0, preferably between 0.6 and 0.8, and further wherein the volume of the second reactor is at least 10%, preferably at least 30% and more preferably at least 50% greater than the volume of the first reactor.

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.

Abstract: A polymerisation process is disclosed in which polyethylene is produced in slurry in a polymerisation reactor in the presence of a Ziegler Natta catalyst and an activator, and slurry containing the polymer is withdrawn from the 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 is withdrawn from the flash tank as a vapour and at least 98 mol %, more preferably at least 98.5 mol %, and most preferably at least 99.5 mol %, of the vapour withdrawn from the flash tank is capable of being condensed at a temperature of between 15 and 40C without compression, wherein a by-product suppressor, which reduces the amount of by-product formed per unit of polyethylene produced by at least 10% compared with an identical polymerisation process where the by-product suppressor is not present, is used in the reactor.

Abstract: Process comprising polymerising in a loop reactor of a continuous tubular construction an olefin monomer optionally together with an olefin comonomer in the presence of a polymerisation catalyst in a diluent to produce a slurry comprising solid particulate olefin polymer and the diluent, wherein the average internal diameter of at least 50% of the total length of the continuous tubular loop reactor is at least 700 mm wherein the HMW polymer is produced in a reactor upstream of the LMW polymer reactor and the ratio of the average internal diameter of the HMW reactor to the average internal diameter of the LMW reactor is between 0.8 and 1.4.

Abstract: A process comprising polymerising in a loop reactor of a continuous tubular construction an olefin monomer optionally together with an olefin comonomer in the presence of a polymerisation catalyst in a diluent to produce a slurry comprising solid particulate olefin polymer and the diluent wherein the average internal diameter of at least 50% of the total length of the reactor is at least 650 millimeters, the solids concentration in the reactor is at least 15 volume % and having a particle size distribution such that (D90?D10)/D50 is less than 2.

Abstract: A process for controlling a slurry phase (co-) polymerisation process in the presence of a polymerisation catalyst, which comprises maintaining the density SPAN of the polymer powder particles (defined as the absolute value of the density difference in g/cm3 between the average density of the polymer particles exiting the reactor with particle size above D90 and the average density of the material with particle size below D10) below 0.005, preferably below 0.003, more preferably below 0.0026, most preferably below 0.0023.

Abstract: Process for polymerising an olefin monomer in at least one continuous tubular loop reactor of a multiple reactor system, optionally together with an olefin comonomer, in the presence of a polymerisation catalyst in a diluent, to produce a slurry containing solid particulate olefin polymer and diluent. The average internal diameter of at least 50% of the total length of the continuous tubular loop reactor is at least 700 mm. A high molecular weight (HMW) polymer is made in a first reactor and a low molecular weight (LMW) polymer is made in a second reactor, the first (HMW) reactor having a space time yield (defined as production of polymer in kg/h per unit volume of reactor) greater than 100 kg/m3/h, and the ratio of space time yield in the first (HMW) reactor to the second (LMW) reactor is greater than 1.

Abstract: An olefin polymerisation process is disclosed in which a slurry of olefin polymer is produced within a polymerisation zone, and a polymer slurry stream is withdrawn from the polymerisation zone and passed through a transfer line to a centrifugal concentrating device, which separates it into a solids-lean stream or streams each having a solids concentration less than that of the polymer slurry stream entering the concentrating device and a solids-rich stream or streams each having a solids concentration greater than that of the polymer slurry stream entering the concentrating device, wherein at least part of the solids-rich stream or streams is recycled back into the polymer slurry stream upstream of the concentrating device and downstream of the polymerisation zone.

Abstract: A process for heating a polymer-containing stream being transferred from a polymerisation reactor to a degassing vessel, comprising passing the stream through a heater comprising a transfer line for the stream and means for heating the transfer line, wherein the pressure drop in the heater is between 5% and 50%, preferably between 10 and 35%, of the total pressure drop between the polymerisation reactor and the entry to the degassing vessel.

Abstract: Process for heating a polymer-containing stream being transferred from a polymerisation reactor to a degassing vessel, comprising passing the stream through a heater comprising a transfer line for the stream and means for heating the transfer line, wherein the ratio of the stream velocity at the outlet of the heater to that at the inlet, Vo/Vi is at least 1.1, typically between 1.2 and 4.

Abstract: A process comprising polymerizing in a loop reactor an olefin monomer optionally together with an olefin comonomer in the presence of a polymerization catalyst in a diluent to produce a slurry comprising solid particulate olefin polymer and the diluent wherein the Froude number is maintained at or below 20 is disclosed.

Abstract: A process comprising polymerising an olefin monomer optionally together with an olefin comonomer in the presence of a polymerisation catalyst in a diluent in a loop reactor which comprises at least 2 horizontal sections and at least 2 vertical sections to produce a slurry comprising solid particulate olefin polymer and the diluent wherein the Froude number in at least 20% of the length of the vertical sections of the reactor loop is less than 85% of the Froude number in at least 20% of the length of the horizontal sections of the loop is disclosed.