Abstract:
Methods for supplying a catalyst to an ethylene slurry loop polymerization reactor and polymers formed therefrom are described herein. The method includes preparing a catalyst slurry in a preparation vessel. The slurry includes a hydrocarbon diluent liquid that contains a Ziegler-Natta catalyst. The catalyst slurry is supplied to a buffer vessel, withdrawn therefrom and supplied to a slurry loop polymerization reactor in which ethylene is polymerized. A co-catalyst is mixed with the Ziegler Natta catalyst in the slurry prior to supplying the catalyst slurry to the slurry loop polymerization reactor. The transfer of the catalyst slurry from the preparation vessel to the buffer vessel and the withdrawal of catalyst slurry from the buffer vessel are controlled to maintain the level of catalyst slurry in the buffer vessel substantially constant relative to the level of catalyst slurry in the preparation vessel.
Abstract:
The present invention relates to a loop reactor suitable for olefin polymerization process comprising: a plurality of interconnected pipes defining a flow path for a polymer slurry, said slurry consisting essentially of an olefin reactant, a polymerization catalyst, liquid diluent and solid olefin polymer particles, means for introducing olefin reactant, polymerization catalyst and diluent into said reactor, a pump suitable for maintaining the polymer slurry in circulation in said reactor, and single settling leg connected to said loop reactor through (a) a take off line extending from said reactor to said settling leg and configured to remove said polymer slurry from said reactor, and (b) a return line extending from said settling leg to said reactor, characterized in that said take off line is radially connected to said single settling leg.
Abstract:
The present invention discloses a slurry loop reactor having at least two loops (1, 2) and comprising a by-pass line (11) connecting two points (12, 13) of the same loop reactor by an alternate route having a different transit time than that of the main route, said by-pass line also collecting the growing polymer of a first loop reactor (1) and sending said growing polymer to an entry point (13) in a second reactor (2).
Abstract:
A method for controlling the injection of catalyst slurry in a polymerization reactor is described herein. The method includes the preparation of polyethylene with a solid catalyst and a hydrocarbon diluents. The method includes providing solid catalyst and a hydrocarbon diluent in one or more storage vessels such that a catalyst slurry is obtained in said vessel, transferring said catalyst slurry from said storage vessel to a mixing vessel wherein said catalyst slurry is diluted for obtaining a suitable concentration for use in a polymerization reaction, pumping said diluted catalyst slurry at a controlled flow rate from said mixing vessel to said polymerization reactor through one or more conduits, by means of a membrane pump provided in each of said conduits, and the membrane pump is controllable as a function of reactant concentration within the polymerization reactor.
Abstract:
An apparatus defined as a set of loop reactors suitable for the polymerization process of a monomer, preferably ethylene and optionally an olefin comonomer, comprising for each of said reactors: a plurality of interconnected pipes P defining a flow path for a polymer slurry, said slurry consisting essentially of ethylene, optionally a comonomer, a polymerization catalyst, liquid diluent and solid olefin polymer particles, means for feeding monomer, optionally a co-monomer, diluent and optionally hydrogen in the reactor, means for feeding a polymerization catalyst in the reactor, a pump suitable for maintaining the polymer slurry in circulation in such reactor, one or more settling legs connected to the pipes P of such reactor for settling of polymer slurry, one or more control valves connected to the outlet of such settling legs, and one or more flash lines for discharging settled polymer slurry out of the reactor characterized in that each of said loop reactors comprises a three-or-more-way valve defining three-or-more ends, one end A being positioned at the outlet of said one or more control valves. A method to switch from series to parallel configuration a set of loop reactors. The use of the apparatus to switch polymerization reactors from parallel to series configuration and vice-versa.
Abstract:
The present invention discloses a method for transforming a single reactor line into a double reactor line wherein the existing single reactor line is equipped with a flash tank for separating the solid polymer product from the flash vapor and wherein the vapor is sent to a system of at least two separating columns allowing the separation of its constituents into monomer, diluent and comonomer.
Abstract:
A method for the copolymerization of ethylene and a C3+ olefin copolymer in a loop reactor system and polymers formed therefrom are described herein. The method generally includes introducing an ethylene monomer, a C3+ alpha olefin comonomer and a diluent carrier liquid into a reactor system comprising at least one loop reactor; supplying at least one polymerization catalyst system to said reactor system; circulating said diluent liquid, ethylene monomer, and alpha olefin copolymer through said loop reactor while copolymerizing said ethylene and said alpha olefin monomer in the presence of said catalyst system to produce a slurry of polymer fluff particles in said diluent carrier liquid; diverting the flow of said slurry through said loop reactor into at least one settling leg connected to the loop reactor and sequentially discharging the settled polymer slurry from said at least one settling leg to withdraw said polymer slurry from said reactor system; and introducing an ethylene monomer co-feed into said loop reactor at least two spaced locations downstream of the point of introduction of ethylene comonomer and diluent in subparagraph a), said ethylene co-feed being introduced in an amount effective to reduce the variation in the ratio of ethylene monomer and comonomer within said 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 discloses a method for controlling the onset and development of swelling in a slurry loop reactor by progressively diluting the reactor, the amount of dilution being driven by the amplitude of the fluctuations measured on some plant measurement.
Abstract:
This invention discloses the use in the production of a polyolefin of a slurry loop reactor wherein all internal parts in contact with the slurry are polished first by a mechanical process to a level of at most 70 RMS roughness value and are subsequently polished by a chemical or electrochemical process, to a final level of at most 40 RMS roughness value.