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 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 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: A method can include consecutively batch processing at least two different polyethylene grades in pellet form in a pellet handling unit. A ratio of a melt flow index (MI) of a first polyethylene in pellet form (MIf) to a MI of a later processed polyethylene in pellet form (MIl) can be smaller than 0.30. The method can include processing an intermediate polyethylene grade in pellet form. An amount of intermediate polyethylene grade processed can be at most 1/100th of a handling capacity of the pellet handling unit. The intermediate polyethylene grade can have the same MI as the later processed polyethylene in pellet form.

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 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 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 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 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 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 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: A process for preparing a homogeneous polyethylene product can include producing a first polyethylene resin in the presence of a metallocene catalyst in a reactor. The first polyethylene resin can have a density of from 0.940 to 0.970 g/cm3. The first polyethylene resin can have a Low Molecular Weight (LMW) with an MI2 of between 2 and 250 g/10 min. The process can include separately producing a second polyethylene resin in the presence of a Ziegler-Natta catalyst in a reactor. The second polyethylene resin can have a High Molecular Weight (HMW) with an MI2 of between 0.01 and 15 g/10 min. The process can include physically blending together the first polyethylene resin and the second polyethylene resin to produce the homogeneous polyethylene product.

Abstract: A process for preparing a homogeneous polyethylene product can include producing a first polyethylene resin in the presence of a metallocene catalyst in a reactor. The first polyethylene resin can have a density of from 0.942 to 0.970 g/cm3 and an HLMI of from 0.5 to 150 g/10 min. The process can include separately producing a second polyethylene resin in the presence of a chromium catalyst in a reactor. The process can include physically blending together the first polyethylene resin and the second polyethylene resin to produce the homogeneous polyethylene product. The homogeneous polyethylene product can include at least 25% by weight of the first polyethylene resin.

Abstract: A process for preparing a polyolefin product can include providing a first high molecular weight (HMW) polyolefin resin having an HLMI of between 0.01 and 5 g/10 min, and separately providing a second low molecular weight (LMW) polyolefin resin having an MI2 of between 1 and 150 g/10 min. A device can be used to continuously physically melt and blend the first HMW polyolefin resin and the second LMW polyolefin resin to produce the polyolefin product. The device can include at least two feeding zones spatially separated and operably connected to each other. At least a art of the first HMW polyolefin resin is introduced in a first feeding zone, and at least a part of the second LMW polyolefin is introduced in a second feeding zone different from the first zone.

Abstract: A process for preparing a multimodal polyethylene product with at least two different polyethylene resins can include producing a first polyethylene resin in the presence of a Ziegler-Natta catalyst in a reactor. The Ziegler-Natta catalyst used for the production of the first polyethylene resin has an average particle size (D50) of at most 15 ?m. The HLMI of the first polyethylene resin is between 0.01 and 5 g/10 min. The process can include separately producing a second polyethylene resin in the presence of a Ziegler-Natta catalyst in a reactor. The MI2 of the second polyethylene resin is between 1 and 150 g/10 min. The process can include physically blending together the first and second polyethylene resins to produce a multimodal polyethylene product. The physical blending can be performed in a device for continuously melting and blending the first and second polyethylene resins.

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 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.