Abstract:
A gas-phase process for polymerizing one or more α-olefins in a fluidized bed reactor in the presence of a polymerization catalyst, said fluidized bed reactor being equipped with a fluidization grid arranged at its base, and external means for recycling and cooling the unreacted gas from the top of said reactor to said fluidization grid, the process being characterized by: (i) a continuous pneumatic recycle of polymer by means of a circulation loop connecting said fluidization grid to the upper region of the fluidized bed reactor; (ii) a continuous discharge of polymer from a zone of said circulation loop having a polymer concentration higher than the polymer concentration inside the fluidized polymer bed.
Abstract:
A process for the multistage polymerization of olefins comprising a gas-phase polymerization carried out in at least two serially connected gas-phase reactors, the continuous discharge of polymer and gas reaction mixture from an upstream reactor into a transfer device and the continuous feeding of polymer from said transfer device to a downstream reactor, said transfer device comprising: a) a separation chamber in which said gas reaction mixture is removed from the polymer; b) at least a couple of lock hoppers working intermittently in parallel, where one of said lock hoppers is continuously filled with the polymer coming from step a), while simultaneously the other one is continuously pressurized by means of a gas comprising the reaction mixture coming from said downstream reactor.
Abstract:
A process for the slurry polymerization of one or more α-olefins in a sequence of at least two loop reactors interconnected by means of a transfer line, the transfer of polymer from a first loop reactor to a second loop reactor comprising the steps: i) establishing a recycle of polymer slurry to the second loop reactor by means of said transfer line, whereby a fraction of polymer slurry S1 withdrawn from said second loop reactor is continuously recycled back to it; ii) discharging a fraction of polymer slurry produced in the first loop reactor into a discharge line connected to said transfer line;
Abstract:
An apparatus for drying polymer particles by means of an inert gas comprising: - a first drying chamber, placed above a first distribution grid, having an annular shape, where the polymer is maintained in fluidized conditions by a first stream of inert gas; - a second drying chamber comprising a tubular body running inside said first drying chamber and protruding downwardly below said first distribution grid.
Abstract:
A gas distribution grid comprising a plurality of trays arranged to form the lateral walls of an inverted cone, said plurality of trays being attached each other to form slots in the overlapping area of adjacent trays.
Abstract:
A process to perform the finishing of a polyolefin produced by polymerization of one or more α-olefins, the process comprising: (1) contacting a polyolefin discharged from a polymerization reactor with a counter-current flow of saturated steam, so as to strip away the gases from said polyolefin and to form condensed steam on the particles of said polyolefin; (2) drying the polyolefin particles by means of a counter-current flow of a dry inert gas, said flow of dry inert gas maintaining the polyolefin particles in fluidization conditions, the evaporation of said condensed steam cooling the polyolefin.
Abstract:
Method and apparatus for the gas-solid separation comprising a separation chamber provided with a rotating hollow body, mounted at the top wall of said separation chamber. The rotating hollow body comprises a plurality of spaced-apart blades defining openings for the passage of gas, but rejecting solid particles entrained by the gas. The apparatus comprises also a cylindrical baffle surrounding the rotating hollow body to further deviate a mixed-phase gas-solids stream entering the separation chamber, and to promote settling of solid particles. The gas-solid separation method can be used to separate a gas-polymer mixture produced in a polymerization process.
Abstract:
A process for the slurry polymerization of one or more α-olefins in a sequence of at least two loop reactors interconnected by means of a transfer line, the transfer of polymer from a first loop reactor to a second loop reactor comprising the steps: i) establishing a recycle of polymer slurry to the second loop reactor by means of said transfer line, whereby a fraction of polymer slurry S1 withdrawn from said second loop reactor is continuously recycled back to it; ii) discharging a fraction of polymer slurry produced in the first loop reactor into a discharge line connected to said transfer line;
Abstract:
An apparatus for drying polymer particles by means of an inert gas comprising: - a first drying chamber, placed above a first distribution grid, having an annular shape, where the polymer is maintained in fluidized conditions by a first stream of inert gas; - a second drying chamber comprising a tubular body running inside said first drying chamber and protruding downwardly below said first distribution grid.