Abstract: The present invention relates to a process for operating a polymer powder degasser vessel, and in particular provides a process for operating a polymer powder degasser vessel which vessel comprises a silo comprising a main vertical cylinder and a hopper at the bottom of the cylinder, there being a polymer powder withdrawal pipe connected to the hopper by which polymer powder is withdrawn from the hopper, and wherein the silo contains a polymer powder which occupies less than 45% of the volume of the silo and the polymer powder passes through the polymer powder degasser vessel in a mass flow manner, further wherein at least one of the following is applied: i) polymer powder is withdrawn from the hopper and recirculated to the silo, wherein the recirculation rate of the polymer powder is at least 30 percent per hour of the polymer powder present in the silo, and ii) a purge gas is provided to the silo via the polymer powder withdrawal pipe or via an inlet located on the hopper at a vertical height which is less

Abstract: The present invention relates to a process for operating a polymer powder degasser vessel, and in particular provides a process for operating a polymer powder degasser vessel which vessel comprises a silo comprising a main vertical cylinder and a hopper at the bottom of the cylinder, there being a polymer powder withdrawal pipe connected to the hopper by which polymer powder is withdrawn from the hopper, and wherein the silo contains a polymer powder which occupies less than 45% of the volume of the silo and the polymer powder passes through the polymer powder degasser vessel in a mass flow manner, further wherein at least one of the following is applied: i) polymer powder is withdrawn from the hopper and recirculated to the silo, wherein the recirculation rate of the polymer powder is at least 30 percent per hour of the polymer powder present in the silo, and ii) a purge gas is provided to the silo via the polymer powder withdrawal pipe or via an inlet located on the hopper at a vertical height which is less

Abstract: The present invention relates to processes and apparatus useful for the production of polymer powder, and in particular to processes and apparatus for the degassing of polymer powder.

Abstract: Polymerization unit for producing polymer powder having at least one polymerization reactor for the polymerization of light (co)monomer(s) having less than 7 carbon atoms, and heavy comonomer(s) having at least 7 carbon atoms, and a degassing section including two (and optionally a third) cylindrical degassing vessels in series. Light (co)monomer(s) are degassed in the first degassing vessel (V1) and recovered, and heavy comonomers are degassed in the second degassing vessel (V2) and recovered. The active polymer powder is optionally polished and/or optionally deactivated in the optional third degassing vessel (V3). The cross-sectional area (S2) of the second degassing vessel is greater than 1.5 times the cross-sectional area (S1) of the first degassing vessel [S2>1.5×S1], and vessels V1 and V2 are equipped with a vent recovery unit (VR) for respectively recovering the light (co-)monomer(s) (VR1) and the heavy comonomer(s) (VR2) from the gases exiting the vessels.

Abstract: Process for the gas-phase polymerization of olefins in a fluidized bed reactor, by a) passing a fluidizing gas containing an olefin monomer through a fluidized bed of polymer particles in the presence of a polymerization catalyst, b) withdrawing a first gaseous stream containing solid particles from the reactor, c) passing the first gaseous stream to a gas/solids separator, separating solid particles, and forming a second gaseous stream containing residual solid particles, d) passing a portion of the second gaseous stream to a heat exchanger(s) to remove heat and e) recycling a portion of the cooled stream from (d) as the fluidizing gas in (a). The fouling rate of the heat exchanger (s) is such that i) the increase in pressure drop across the heat exchanger is equivalent to less than 5%/year, and/or ii) the decrease in heat transfer of the heat exchanger is equivalent to less than 5%/year.

Abstract: Process for the polymerization of olefins in a polymerization reactor system including (i) a gas phase reactor having a gas outlet and one or more withdrawal lines for withdrawal of a polymer-containing stream, (ii) a recycle loop for recycling gas exiting the reactor through the gas outlet back to the reactor, (iii) a polymer separation system for separating reactants from the polymer product in the withdrawn polymer-containing stream, and (iv) a recycle system for recycling reactants removed from the reactor in the withdrawn polymer-containing stream back to the reactor. A scavenger is introduced directly into one or more of the recycle loop, the polymer separation system and the recycle system.

Abstract: Process for polymerizing olefins in a polymerization reactor system including at least first and second introduction points by which the same reaction component may be introduced directly at different locations on the reactor system. At a first time, the reaction component is introduced through at least the first introduction point, such that a proportion X of the reaction component which is introduced through the first and second introduction points is introduced through the first introduction point. At a second, later, time the same reaction component is introduced through at least the second introduction point and such that a proportion Y of the reaction component which is introduced through the first and second introduction points is introduced through the first introduction point. Y is less than X, and at least one of the first and second introduction points is located on the reactor system at a location not on the reactor.

Abstract: Method for controlling a process for the production of a polymer by polymerization of a monomer and a comonomer. The process includes maintaining a substantially constant effective flow ratio (EFR), the effective flow ratio being defined as EFR=(Qcomo?Lcomo)/(Qmono?Lmono), Qcomo and Qmono being, respectively, flow rates of comonomer and monomer to the reactor, Lcomo and Lmono being, respectively, losses of comonomer and monomer.

Abstract: The present invention relates to processes and apparatus useful for the production of polymer powder, and in particular to processes and apparatus for the degassing of polymer powder.

Abstract: The present invention relates to a process for the polymerisation of olefins in a polymerisation reactor system and in particular provides a process for the polymerisation of olefins in a polymerisation reactor system, the polymerisation reactor system comprising: (i) a gas phase reactor having a gas outlet and one or more withdrawal lines for withdrawal of a polymer-containing stream, (ii) a recycle loop for recycling gas exiting the reactor through the gas outlet back to the reactor, (iii) a polymer separation system for separating reactants from the polymer product in the withdrawn polymer-containing stream, and (iv) a recycle system for recycling reactants removed from the reactor in the withdrawn polymer-containing stream back to the reactor, characterised in that a scavenger is introduced directly into one or more of the recycle loop, the polymer separation system and the recycle system.

Abstract: The present invention relates to a process for the polymerisation of olefins in a polymerisation reactor system and in particular provides a process for the polymerisation of olefins in a polymerisation reactor system, the polymerisation reactor system comprising at least first and second introduction points by which the same reaction component may be introduced directly at different locations on the reactor system, wherein i) at a first time the reaction component is introduced through at least the first introduction point and such that a proportion X of the reaction component which is introduced through said first and second introduction points is introduced through the first introduction point, and ii) at a second, later, time the same reaction component is introduced through at least the second introduction point and such that a proportion Y of the reaction component which is introduced through said first and second introduction points is introduced through the first introduction point, wherein Y is less

Abstract: Process for the continuous transition between two different and compatible polymerization catalysts.

Abstract: Process for transitioning from the production of a first polymer to the production of a second polymer in a gas phase fluidized bed or stirred bed reactor by a) conducting a first polymerization reaction in the reactor using a first polymerization catalyst system to produce a first polymer, b) stopping the first polymerization reaction and removing at least the majority of the polymer in the reactor, c) introducing into the reactor a seed-bed containing at least 50 ppm of contaminants, in which the seedbed is maintained under at least 50 ppm but less than 500 ppm of contaminants during storage, and d) treating the seed-bed in the reactor to reduce the amount of contaminants. Step e) involves conducting a second polymerization reaction in the reactor to produce a second polymer.

Abstract: The present invention relates to a process for the gas-phase polymerisation of olefins in a fluidised bed reactor, which process comprises: a) passing a fluidising gas comprising one or more olefin monomers through a fluidised bed of polymer particles in the presence of a polymerisation catalyst, b) withdrawing a first gaseous stream comprising solid particles from the top of the reactor, c) passing the first gaseous stream to a gas/solids separator, separating solid particles therefrom, and forming a second gaseous stream comprising residual solid particles, d) passing at least a portion of the second gaseous stream to one or more heat exchangers to remove the heat of reaction, and e) recycling at least a portion of the cooled stream from step (d) as the fluidising gas in step (a), characterised in that the rate of fouling of the one or more heat exchangers is such that i) the increase in pressure drop across the heat exchangers is equivalent to less than 5% per year, and/or ii) the decrease in heat transfer

Abstract: Method for operating a process for producing a polymer by polymerization of a monomer and an optional comonomer in a gas phase fluidized bed reactor during steady-state and non-steady-state conditions.

Abstract: Process for gas phase polymerization of olefins in a fluidized bed reactor by (a) passing a fluidizing gas containing at least one olefin monomer through a fluidized bed of polymer particles in the presence of a polymerization catalyst to produce polymer at a polymer production rate of C Tonnes/hour, (b) withdrawing a first gaseous stream containing solid particles from the top of the reactor, (c) passing the first gaseous stream to a gas/solids separator, separating solid particles therefrom, and forming a second gaseous stream containing residual solid particles, (d) passing a portion of the second gaseous stream to at least one heat exchanger to remove heat of reaction whereby residual solid particles contact the heat exchanger, and (e) recycling a portion of the cooled stream from step (d) as the fluidizing gas in step (a). The heat exchangers have a heat exchange surface area which totals less than 120×C m2.

Abstract: Process for maintaining a continuous gas-phase (co-) polymerization of olefins in a large fluidized bed reactor in a homogeneous mode while operating at high space time yield and condensation rate in the presence of a polymerization catalyst.

Abstract: Process for the transition between an ethylene co-polymerization process in a polymerization reactor in the presence of a catalyst and of ethylene E and an olefin co-monomer A to produce an ethylene copolymer PEA into an ethylene co-polymerization process carried out in the same polymerization reactor in the presence of a catalyst and of ethylene E and an olefin co-monomer B to produce an ethylene copolymer PEB. Co-monomers A and B are different and are both present in the reactor during at least part of the transition from PEA to PEB. The transition is performed continuously by (i) starting the transition by stopping steady state production of ethylene copolymer PEA and (ii) ending the transition when steady state production of ethylene copolymer PEB is achieved.

Abstract: Process for the gas phase polymerization of olefins, in particular, with recycle of fines to the reaction zone. The process includes (a) polymerizing an olefin in a reaction zone in which a bed of polymer particles is maintained in an agitated state by passing a fluid stream through the bed, (b) withdrawing the fluid stream from the reactor after it has passed through the bed of polymer particles, (c) separating entrained solids from the withdrawn fluid stream, and (d) returning the separated entrained solids to the reaction zone. The polymer production rate of the process is at least 40 tonnes/hour, and the separated solids from step (c) are returned to the lower half of the bed of polymer particles in the reaction zone.

Abstract: The present invention relates to a process for transitioning from the production of a first polymer to the production of a second polymer in a gas phase fluidised bed or stirred bed reactor, said process comprising the steps of: a) Conducting a first polymerisation reaction in the reactor using a first polymerisation catalyst system to produce a first polymer, b) Stopping the first polymerisation reaction and removing at least the majority of the polymer in the reactor, c) Introducing into the reactor a seed-bed comprising at least 50 ppm of contaminants, wherein the seedbed has been maintained under at least 50 ppm but less than 500 ppm of contaminants during storage d) Treating the seed-bed in the reactor to reduce the amount of contaminants, e) Conducting a second polymerisation reaction in the reactor to produce a second polymer.