Abstract: The present invention relates to a process for the polymerization of an olefin monomer. In particular, the present invention relates to a process for the polymerization of an olefin monomer and one or more optional comonomers in presence of a polymerization catalyst and hydrogen, said process being characterized by an improved control of the hydrogen concentration in the polymerization reactor. In addition, the present invention provides for an improved hydrogen feeding system to a polymerization reactor. Furthermore, the present invention provides for a polymerization reactor comprising such an improved hydrogen feeding system.

Abstract: The present invention discloses a slurry loop reactor comprising at least two loop reactors connected in series and wherein the line connecting the two loops is subject to a dynamic pressure difference.

Abstract: The present invention relates to a process of preparing a polyolefin in a loop reactor by introducing anti-fouling agent in by-pass pipes. Also, the invention relates to the use of anti-fouling agent to prevent blockage by feeding the anti-fouling agent into the by-pass pipes of the loop reactor.

Abstract: The present invention relates to a method for feeding metallocene catalyst slurry to an olefin polymerization loop reactor (1) using a positive displacement device (5) positive displacement device comprising a first chamber and a second chamber, each chamber having an inlet and an outlet and each chamber comprising an ball arranged between the walls of said chamber, wherein said chambers are connected to each other by a pump chamber operably connected to a pump, wherein, the difference between the diameter of said ball and the diameter of said chamber is comprised between 5 to 200 times the average particle size (d50) of said catalyst.

Abstract: The present invention relates to a process for preparing catalyst slurry in a catalyst slurry preparation system and supplying catalyst slurry to an ethylene polymerization loop reactor wherein an accurate control of the pressure within said catalyst slurry preparation system is provided.

Abstract: The present invention relates to a method for consecutively producing at least two different polyethylene resins in one slurry loop reactor, comprising producing a first polyethylene resin in the presence of a Ziegler-Natta and/or a Chromium catalyst, and consecutively producing a second polyethylene resin in the presence of a metallocene catalyst, characterized in that the ratio of the melt flow index of the first produced polyethylene resin to the melt flow index of the second produced polyethylene resin is at least 0.3.

Abstract: The present invention relates to a method of continuously feeding catalyst slurry into an olefin polymerization reactor comprising the steps of: a) continuously feeding catalyst slurry into the reactor through a catalyst feeding line and then through a valve connected to the wall of the reactor, wherein said valve comprises a piston device comprising an actuator and a hollow casing, wherein said piston is connected to the actuator and wherein said piston is arranged in the hollow casing; and b) closing said valve by moving the piston through at least part of said valve towards the reactor and at least until the wall of the reactor, upon at least partial blockage of said valve.

Abstract: The invention relates to a catalyst metering device with a valve formed of an iron-based alloy steel hardened to a Rockwell hardness C of at least 60. The device can be used for metering of a catalyst for an ethylene polymerization reaction. The invention further relates to ethylene polymerization wherein the catalyst is metered in a catalyst metering device with a iron-based alloy steel hardened valve, as well as to a ethylene polymerization reactor comprising such a catalyst metering device.

Abstract: The present invention relates to a process of preparing a polyethylene in a loop reactor in the presence of antifouling agent comprising the steps of: a) feeding into said loop reactor diluent, monomers, optionally hydrogen, and optionally one or more co-monomers to produce a liquid phase; b) introducing antifouling agent into said loop reactor, c) introducing a catalyst into the liquid phase to produce a slurry; and d) polymerizing the monomers and optional co-monomers to form the polyethylene, characterized in that the time difference between introduction of the antifouling agent and introduction of the catalyst is at most 3 hours.

Abstract: The present invention relates to a process of preparing a polyolefin in a loop reactor by introducing anti-fouling agent through a sleeve provided around at least part of the shaft of the pump. Also, the invention relates to the use of anti-fouling agent to prevent or reduce fouling by feeding the anti-fouling agent against the impeller of the pump upon introduction to the loop reactor.

Abstract: The present invention relates the use of a pump in a loop reactor for the production of polyethylene, as well as a reactor comprising such pump and methods for producing polyolefin by means of such reactor. The pump according to the invention is characterized in that it is an axial flow impeller circulation pump, wherein the impeller comprises 6 blades and wherein the pump is fixed on a spring supported frame. Use of the pump according to the present invention allows for preparation of homogeneous polyethylene products that meet high quality standards from the complicated ethylene polymerization mixtures while at the same time being produced with low energy consumption.

Abstract: The present invention concerns an improved method for introducing free carbon black additive into a polymer powder or fluff, and in particular into polyethylene powder.

Abstract: The present invention relates to a process for improving the polymerization of ethylene and one or more optional co-monomer(s) in a polymerization loop reactor characterized in that said process comprises the step of controlling the hydrogen/monomer ratio along the path of the reactor by multiple, spatially separated, feeding of hydrogen along the path of the loop reactor. In particular, the invention provides a process for controlling, and preferably narrowing, the molecular weight distribution of the produced polymer particles. In another aspect, the invention relates to a polymerization loop reactor suitable for the polymerization process of ethylene and an optional olefin co-monomer, wherein the molecular weight distribution of the produced ethylene polymer can be controlled.

Abstract: This invention is related to the field of olefin polymerisation in double loop reactors and especially to the polymerisation of olefins with very active catalyst systems. It discloses a method for reducing blockage when transferring polymer product from the first loop to the second loop of a double loop reactor.

Abstract: The present invention relates to a method for optimizing the sequential use of at least two ethylene polymerization catalysts to an ethylene polymerization loop reactor, comprising: transferring to a mixing vessel a first ethylene polymerization catalyst and a first diluent, thereby providing a first catalyst slurry, transferring said first catalyst slurry from said mixing vessel to an ethylene polymerization loop reactor at a concentration suitable for polymerizing ethylene, increasing the ratio of said diluent to said first ethylene polymerization catalyst in said first catalyst slurry, stopping the supply of said first catalyst slurry to said mixing vessel, stopping the supply of said first catalyst slurry to said ethylene polymerization loop reactor, stopping the supply of ethylene to said ethylene polymerization loop reactor, removing said first catalyst slurry from said ethylene polymerization loop reactor, emptying said mixing vessel, optionally rinsing said mixing vessel with fresh diluent, transfe

Abstract: The present invention relates to a process for cleaning a catalyst slurry preparation system and/or a catalyst preparation system. More particularly, the invention relates to a cleaning process for a catalyst preparation system and/or for a catalyst slurry preparation system, wherein an aqueous catalyst inactivation agent is used to rinse the systems, or any parts thereof. The catalysts used in the present invention may be chromium, Ziegler-Natta or metallocene catalysts.

Abstract: The present invention relates to a method for producing a catalyst slurry blend suitable for polymerizing ethylene in an ethylene polymerization loop reactor for obtaining an at least trimodal polyethylene product, comprising the steps of: transferring a first ethylene polymerization catalyst at a first mass flow rate to a mixing vessel, simultaneously transferring a second ethylene polymerization catalyst at a second mass flow rate to said mixing vessel, thereby in situ providing a catalyst slurry blend, wherein said second ethylene polymerization catalyst is different from the first ethylene polymerization catalyst, adjusting and monitoring said first and second mass flow rates, thereby obtaining said catalyst slurry blend at a concentration suitable for polymerizing ethylene, and feeding said catalyst slurry blend to an ethylene polymerization double loop reactor producing said at least trimodal polyethylene product.

Abstract: The present invention relates to a method for optimizing the sequential feeding of at least two ethylene polymerization catalysts to an ethylene polymerization reactor, comprising: transferring to a mixing vessel a first ethylene polymerization catalyst and a first diluent, decreasing the concentration of said first ethylene polymerization catalyst in said mixing vessel, transferring to said mixing vessel a second ethylene polymerization catalyst and a second diluent, progressively replacing said first ethylene polymerization catalyst by said second ethylene polymerization catalyst and said first diluent by said second diluent, increasing the concentration of said second ethylene polymerization catalyst in said mixing vessel, sequentially transferring said first ethylene polymerization catalyst and said second ethylene polymerization catalyst from said mixing vessel to an ethylene polymerization reactor.

Abstract: The present invention relates to a process for the polymerization of an olefin monomer. In particular, the present invention relates to a process for the polymerization of an olefin monomer and one or more optional comonomers in presence of a polymerization catalyst and hydrogen, said process being characterized by an improved control of the hydrogen concentration in the polymerization reactor. In addition, the present invention provides for an improved hydrogen feeding system to a polymerization reactor. Furthermore, the present invention provides for a polymerization reactor comprising such an improved hydrogen feeding system.

Abstract: The present invention discloses multiple loop reactor wherein one of the settling legs transferring polymer product from one loop to a further loop can be taken out of service or re-opened without interfering with the operation of said multiple loop reactor.