Bp Chemicals Limited

Bp Chimie Societe Anonyme

Charles Raufast

Frederic R Morterol

Andre Dumain

Andre Martens

Jean A Maurel

Jean-Marie Iffly

Daniel Brule

Alain Marsaly

The present invention relates to a gas phase fluidized bed reactor (1) comprising an upright tubular portion (2) having a fluidization grid (4) in the lower part thereof. According to the invention the upright tubular portion (4) is provided with an external conduit (13) which connects a lower orifice (14) which is above the fluidization grid (4) and an upper orifice (15) which is a height above the lower orifice (14). The invention also relates to a gas phase polymerization process carried out in the reactor.

Fluidized bed reactor with polymer recycle line

The present invention relates to a continuous process for the polymerization of an alpha-olefin having from 2 to 12 carbon atoms, which is carried out in a gas phase polymerization reactor by bringing a gaseous reaction mixture, containing the alpha-olefin to be polymerized, into contact with a catalyst system of the Ziegler-Natta type consisting of a solid catalyst comprising at least one compound of a transition metal belonging to groups IV, V or VI of the Periodic Table, of the elements, and of a cocatalyst comprising at least one organometallic compound of a metal belonging to groups II or III of the Periodic Table in which the polymerization reactor is fed with alpha-olefin at a constant rate.

Gas phase polymerisation process

Polymerization process

The present invention relates to a process and a device for introducing a catalytically active powder into a reactor (20) for gas phase alpha-olefin polymerization. The device comprises a storage vessel (3) containing the powder, a metering valve (4) delivering metered quantities of the powder into an intermediate chamber (5) comprising at least one obstacle (6) separating an upper part (5a) of the chamber (5) comprising an auxiliary gas inlet (2a) from a lower part (5b) terminated by an outlet orifice (5c). A connecting pipe (18) connects the outlet orifice (5c) to a mixing device (8) situated on a conveying pipework (15) communicating with the reactor (20). The powder is introduced into the reactor in a dilute suspension form and in a more uniform rate.

Process and device for introducing a powder into a reactor

The present invention relates to a process and a device for polymerizing alpha-olefins such as ethylene or propylene in a gas phase. The device comprises a gas phase polymerization reactor (5) into which a suspension of prepolymer particles in liquid saturated hydrocarbon(s) is continuously introduced. The prepolymer suspension is prepared in one or more prepolymerization vessels (14) and is continuously passed to a post-treatment unit comprising a degassing means (10) wherein most of the dissolved unreacted olefinic monomer(s) is separated. Preferably, the post-treatment unit may comprise a particle separation means (11) for removing the finest and/or coarsest prepolymer particles from the suspension and/or a concentration means (11a) for concentrating the suspension. High activity catalyst can be used in the process with reduced amounts of prepolymer agglomerates. Prepolymer can be obtained with a constant quality and a desired size.

Process and device for the gas phase polymerization of alpha-olefins

A fluidized bed apparatus (1) having a fluidization grid (2) below which is positioned a tuyere (5) for guiding fluidization gas to the fluidization grid (2). The tuyere (5) comprises a widening pipe the wider end (6) of which is positioned towards the fluidization grid (2) and has an area which is substantially the same as the cross-sectional area of the fluidized bed apparatus (1) and is 2 to 30 times that of the area of the narrower end (7) of the widening pipe. The process for feeding fluidization gas to a fluidized bed using such apparatus enables a good gas distribution across the bed to be achieved with a modest additional pressure drop. The invention is particularly useful for apparatus e.g. greater than 3 m in diameter.

Fluidized bed apparatus and process for feeding gas to a fluidized bed

Process for discharging solid particulate products present in a fluidized bed reactor in which the polymerization or copolymerization of alpha-olefins is carried out, in a system consisting of a vessel connected to the reactor by way of a pipe provided with a first valve and connected to a reservoir situated downstream by way of a pipe provided with a second valve, the said method being characterized in that:

Fluidized bed discharge process

The present invention relates to a fluidized bed apparatus comprising a fluidization grid arranged in the lower part of this apparatus, this grid being provided at its center with a circular aperture communicating with a discharge chamber and occurring in the form of a surface of revolution consisting of the joined lateral surfaces of at least two coaxial truncated cones of revolution, virtual vertices of which are oriented downwards.

Gas distribution plate for fluidization

The invention relates to a process and a device for degassing and converting into pellets polyolefins from a gas-phase reactor. A device according to the invention comprises, in combination (FIG. 1):

Apparatus for degassing and pelleting polyolefins

Apparatus for the production of polyolefins by the polymerization of alpha-olefins in the gas phase, in several stages, in at least two polymerization reactors interconnected by a transfer device making it possible to transfer the polyolefins resulting from the first reactor into the second reactor, in which the polymerization is continued under conditions identical to or different from those of the first reactor.

Polymerization in several stages of alpha-olefins in the gas phase

Process for gas phase polymerization of olefins using a highly active catalyst in a fluidized bed reactor (1), comprising a recator body (2) partially occupied by the fluidized bed and surmounted by a disengagement chamber (3). The gas mixture withdrawn from the disengagement chamber (3) is fed to a dust separator (6) e.g. a clycone, to separate the fine particles entrained by the gas. The gas is cooled, compressed and recycled to the base of the reactor. The particles are withdrawn from the dust separator (6) by a mixing device (8) which mixes the particles with a carrier gas. The carrier gas and particles are recycled to the reactor where they are introduced into the reactor body (2) through an opening in the side wall thereof at a position above the fluidized bed, but below the disengagement chamber (3). The velocity of the particles introduced into the reactor is insufficient to cause them to be blown directly into the bed.

Process for gas phase polymerization of olefins in a fluidized bed

A process for detecting anomalies in a fluidized bed, e.g. the incidence of agglomeration in gas-fluidized bed polymerization, comprises sensing and converting into electrical signals the pressure at one level, or the pressure difference between two or more levels in the reactor, processing these signals by computer to produce a pressure spectrum and comparing with a reference spectrum obtained in the absence of anomalies. The device comprises one or more pressure sensors 11,12,13, which measure the pressure at various levels in the reactor 1, and a computer 27.

Detection of anomalies in gas fluidized bed polymerization

The present invention relates to a rotary-type metering device making it possible to dispense granular substances consisting of fine particles which are difficult to handle. The metering device consists of a spherical core rotating around a horizontal axis inside a casing comprising a feed orifice and an outlet orifice. The spherical core comprises at least one cavity having an opening at the surface of the core, and sides and bottom within the core. This cavity has the shape of a volume consisting of two volumes of revolution, contiguous and coaxial, V.sub.1 and V.sub.2, with an axis perpendicular to the axis of rotation of the spherical core. The volume V.sub.1 is a truncated cone of revolution or a cylinder of revolution.

Pressure locked rotary trap chamber

The invention relates to a process for degassing and pelletizing polyolefin particles produced by a gas phase polymerization. The polyolefin particles are submitted to a primary degassing, preferably at the outlet of a reactor for catalytic polymerization in the gas phase. Then the polyolefin particles are subjected to a secondary degassing step comprising agitating the particles by a mechanical stirrer and converting the mechanical energy therefrom into heat such that the temperature of the particles is brought to between 80.degree. and 120.degree. C. which is close to minimum sintering temperature Ts so that the polyolefin particles are substantially freed from the gases accompanying them. The heated degassed polyolefin particles are then pelletized in an extruder of a pelleting unit. Optionally, during the secondary degassing step an inert gas such as nitrogen is circulated to facilitate evacuation of gases from the particles, and/or gas containing oxygen and/or water vapor is circulated to inactivate any catalyst in the particles. Furthermore, during the secondary degassing step the polyolefin particles heated by the conversion of mechanical energy may attain a temperature between Ts-5.degree. C. and Ts+5.degree. C., preferably between Ts-2.degree. C. and Ts+2.degree. C. The polyolefin particles can be polyethylene or copolymers of ethylene and of higher alpha-olefins having 3 to 12 carbon atoms.

Process of degassing and pelletizing polyolefins

Device and process for introducing a powder with catalytic activity into a fluidized bed polymerization reactor (1), the said device comprising:

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Saint Julien les Martigues, France

Charles Raufast