Abstract: Process for introducing a polymerization catalyst in solid form into a gas-phase fluidized bed using an injection device having an inner tube of internal cross-sectional area of 10-100 mm2 and an outer tube forming an annulus around the inner tube with a cross-sectional area of 1-10 times the internal cross-sectional area of the inner tube. The polymerization catalyst and a carrier gas are passed through the inner tube into the gas-phase fluidized bed at a carrier gas linear velocity of 4-14 m/s and a carrier gas mass flow rate of 10-35 kg/h. A shielding gas is passed through the outer tube and into the gas-phase fluidized bed at a shielding gas linear velocity of 1-10 times the linear velocity of the carrier gas through the inner tube and at a shielding gas mass flow rate of 100-500 kg/h. No cooled recycle process gas is provided to the injection device.

Abstract: Process for polymerization and, in particular, to a process for start-up of a gas phase fluidized bed polymerization reaction involving one or more monomers using a catalyst in a reactor. The process includes providing a start-up bed of particles in the reactor in the presence of the one or more monomers but in the absence of the catalyst, introducing at T0 catalyst to the reactor to initiate reaction and start-up polymer production at a time Ti, Ti being between 1 and 6 hours after T0. The value of Xi is less than a threshold value, wherein: Xi=Cumulative production in the time period T0 to Ti/(Cumulative catalyst injection the time period T0 to Ti*PiC2=), where PiC2= is the ethylene partial pressure in the reactor at the time Ti, subsequently stopping the injection of catalyst, and taking a corrective action to address the low value of Xi.

Abstract: Process for polymerization and, in particular, to a process for start-up of a gas phase fluidized bed polymerization reaction involving one or more monomers using a catalyst in a reactor. The process includes providing a start-up bed of particles in the reactor in the presence of the one or more monomers but in the absence of the catalyst, introducing at T0 catalyst to the reactor to initiate reaction and start-up polymer production at a time Ti, Ti being between 1 and 6 hours after T0. The value of Xi is less than a threshold value, wherein: Xi=Cumulative production in the time period T0 to Ti/(Cumulative catalyst injection the time period T0 to Ti*PiC2=), where PiC2= is the ethylene partial pressure in the reactor at the time Ti, subsequently stopping the injection of catalyst, and taking a corrective action to address the low value of X.

Abstract: Process for introducing a solid polymerization catalyst into a gas-phase fluidized bed using an injection device having an inner tube of internal cross-sectional area of 10 to 100 mm2 and an outer tube forming an annulus around the inner tube with a cross-sectional area of 1 to 10 times the internal cross-sectional area of the inner tube. The polymerization catalyst and a carrier gas are passed through the inner tube and into the gas-phase fluidized bed at a carrier gas linear velocity of 4 to 14 m/s and a carrier gas mass flow rate of 10-35 kg/h. A shielding gas is passed through the outer tube and into the gas-phase fluidized bed at a linear velocity of 1 to 10 times the carrier gas linear velocity through the inner tube and at a mass flow rate of 100-500 kg/h. No cooled recycle process gas is provided to the injection device.

Abstract: Process for introducing a polymerisation catalyst in solid form into a gas-phase fluidised bed using an injection device having an inner tube of internal cross-sectional area of 10-100 mm2 and an outer tube forming an annulus around the inner tube with a cross-sectional area of 1-10 times the internal cross-sectional area of the inner tube. The polymerisation catalyst and a carrier gas are passed through the inner tube into the gas-phase fluidised bed at a carrier gas linear velocity of 4-14 m/s and a carrier gas mass flow rate of 10-35 kg/h. A shielding gas is passed through the outer tube and into the gas-phase fluidised bed at a shielding gas linear velocity of 1-10 times the linear velocity of the carrier gas through the inner tube and at a shielding gas mass flow rate of 100-500 kg/h. No cooled recycle process gas is provided to the injection device.

Abstract: The present invention relates to a process for polymerisation, and, in particular, to a process for start-up of a gas phase fluidised bed polymerisation reaction, said reaction comprising polymerisation of one or more monomers using a catalyst in a reactor, and said process comprising: a) providing a start-up bed of particles in the reactor in the presence of the one or more monomers but in the absence of the catalyst, b) introducing catalyst to the reactor to initiate reaction and start-up polymer production, said introduction being designated as time T0, c) at a time Ti, Ti being between 1 and 6 hours after T0, the value of Xi is less than a threshold value, wherein: Xi=Cumulative production in the time period T0 to Ti (Cumulative catalyst injection the time period T0 to Ti*PiC2=), PiC2= being the ethylene partial pressure in the reactor at the time Ti, d) subsequently stopping the injection of catalyst, e) taking a corrective action to address the low value of Xi.

Abstract: The present invention relates to a process for polymerisation in a gas-phase fluidised bed, and in particular to a process for the introduction of a polymerisation catalyst in solid form into a gas-phase fluidised bed, which process comprises using an injection device having an inner tube of internal cross-sectional area of 10 to 100 mm2 and an outer tube forming an annulus around said inner tube with a cross-sectional area of 1 to 10 times the internal cross-sectional area of the inner tube, and passing said polymerisation catalyst and a carrier gas through the inner tube and into the gas-phase fluidised bed at a linear velocity of said carrier gas of 4 to 14 m/s and at a mass flow rate of carrier gas in the range 10-35 kg/h, and passing a shielding gas through the outer tube and into the gas-phase fluidised bed at a linear velocity of said shielding gas of 1 to 10 times the linear velocity of the carrier gas through the inner tube and at a mass flow rate of the shielding gas in the range 100-500 kg/h, where