JPH0333163B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to an apparatus for gas phase polymerization of olefins.

In recent years, gas phase polymerization has been attracting attention as a polymerization method for olefins, but when conventional gas phase polymerization equipment is used, problems inherent to gas phase polymerization, such as the formation of hot spots, can be avoided. However, it has not been possible to economically and stably produce a polymer of good quality. Conventionally known gas phase polymerization equipment for olefins is broadly divided into vertical fluidized bed type and horizontal fluidized agitated bed type.
The former tends to produce popcorn-shaped, flake-shaped, or block-shaped polymers depending on the type of catalyst, and the gas components are recycled to remove polymerization heat, but this gas circulation requires considerable cost. It is said that As for the latter, for example,
Devices disclosed in JP-A-2019 and JP-A-51-86584 are known, but in both cases it is difficult to completely suppress the formation of hot spots, and it is difficult to prevent the formation of block polymers. This has the disadvantage that stirring requires a large amount of power.

The present inventors aimed to improve a horizontal fluidized stirred bed type gas phase polymerization apparatus for olefins, which makes it difficult to generate hot spots during polymerization, and as a result, it is possible to suppress the formation of block polymers. Although we have developed a polymerization device that requires less power for stirring and can economically and stably produce polymers with an appropriate particle size distribution, improvements are still desired in practical terms, including the difficulties involved in manufacturing. Ta.

The present invention satisfies the above-mentioned requirements and provides a highly practical polymerization device that is easy to manufacture and that can more stably, uniformly, and efficiently supply gas components that require raw material olefin gas to the polymerization device. This is what we provide.

The olefin gas phase polymerization apparatus of the present invention has a plurality of opening groups consisting of a plurality of openings dotted on the lower curved surface of the horizontal fluidized stirred bed polymerization apparatus main body, and a plurality of olefin supply chambers corresponding to each opening group. It was established in

As understood from the above, the present invention is an improvement in the method of supplying a gas component, which requires olefin gas, to a horizontal fluidized stirred bed polymerization apparatus.

The present invention will be explained below based on the drawings.

FIG. 1 is a partially cut away perspective view showing the characteristic parts of the device of the present invention.

A plurality of opening groups 3 consisting of a plurality of openings 2 are dotted on the lower curved surface of the horizontal fluidized stirred bed type polymerization apparatus main body 1, and olefin supply chambers corresponding to the number of opening groups are provided at the bottom thereof, and polymerization is carried out through the openings. Communicate with the main body of the device. Preferably, each aperture group has the same number of apertures and the same size. It is preferable to arrange the openings so that the openings are distributed substantially uniformly in the axial direction of the polymerization apparatus. It is preferable that the aperture groups are arranged in a staggered manner in the axial direction, as shown in FIG.

In the present invention, the term "distributed" means that they are not arranged densely so as to cover the entire lower curved surface.

Although the shape of the aperture group is arbitrary, a circular shape is preferable. The ratio d/D between the cross-sectional diameter D of the polymerization apparatus main body and the diameter d of the opening group is preferably 0.3 to 0.6, particularly 0.4 to 0.5.

The number of aperture groups may be two or more, but the optimum number depends on the axial length of the polymerization device.

The opening is located on the lower curved surface of the polymerization equipment body, with a hole diameter of 0.5~
An appropriate method may be used, such as making small holes of about 5 mm, more preferably 1 to 2 mm, at intervals of 0.5 to 50 mm, or providing small chambers having small holes in the side wall at regular intervals. The olefin supply chamber 4 is provided independently for each opening group.

The main body of the horizontal fluidized stirred bed polymerization apparatus of the present invention has a hollow cylindrical horizontal structure, and the length ratio to the vertical cross-sectional diameter inside the hollow cylinder is usually 0.5 to 10.
Particularly preferably 1 to 5. Further, this device may be provided with a chamber such as a vertical cylindrical body in the upper part, if necessary. In this case, the ratio of the cross-sectional diameter of the upper vertical cylinder to the internal cross-sectional diameter of the horizontal hollow cylinder of the main body is usually 0.6.
~1.0 is preferred. The stirring device used has a drive shaft at the center in the longitudinal direction of a horizontal hollow cylinder and one or more stirring blades. Examples of the stirring blade include a paddle type, an inclined paddle type, a spiral type, and a blade equipped with a scraping plate for scraping the inner wall of the polymerization apparatus. Although a plurality of stirring blades are usually provided, particularly favorable results are obtained when the distance between the inner wall of the polymerization apparatus and the tip of the stirring blade is about 3 to 10 mm.

The polymerization catalyst is usually supplied to the polymerization apparatus as a slurry of saturated hydrocarbons or as a solid. At this time, the co-catalyst may be added at the same time or may be supplied separately. It is also preferable to supply hydrogen or nitrogen gas to prevent clogging of the catalyst inlet.

A mixture of the total amount of recycle gas leaving the polymerization apparatus and the overflow product polymer is usually fed to a cyclone. The gas flow rate in the piping from the polymerization apparatus to the cyclone is preferably 10 m/sec to 50 m/sec in order to prevent the polymer from adhering to the walls.

As the cyclone, a well-known type of cyclone is used as appropriate. Preferably, the structure is as simple as possible.
For example, those having the basic structure described in Chemical Engineering Handbook, page 1233 (published by Maruzen, 1979) can be used as appropriate. The inner surface of the cyclone must be smoothed by buffing. A receiver for the produced polymer is provided at the bottom of the cyclone. The smaller the receiver, the better. It is also preferred that the receiver be externally cooled to prevent the polymer from dissolving therein. The produced polymer may be withdrawn from the system by any suitable method, such as intermittent withdrawal by intermittent opening and closing of a ball valve or continuous withdrawal using a ball valve type control valve.

FIG. 2 is a schematic process diagram showing an example of olefin polymerization using the apparatus of the present invention.

A raw material olefin gas 5, a catalyst 6, and, if necessary, hydrogen 7 are supplied to a horizontal polymerization apparatus 1 equipped with a stirring blade. As the raw material olefin gas, α-olefins usually having 12 or less carbon atoms, such as ethylene, propylene, 1-butene, 1-hexene, and 4-methylpentene-1, are used alone or in a mixture of two or more. Furthermore, dienes such as butadiene, 1,4-hexadiene, and ethylidene norbornene can be further added to these olefins for copolymerization.

The temperature of the polymerization reaction tank is 0 to 125℃, especially 20 to 100℃
is preferred. The pressure is normal pressure to 70Kg/cm ² G, especially 2
~60Kg/cm ² G is preferred. The rotation speed of the stirring device is 10
~500 rpm, especially 20-300 rpm is preferred. The circulating gas linear velocity in the polymerization equipment is 0.5 to 25 based on the cross-sectional area.
cm/sec, particularly 1 to 10 cm/sec is preferred. As the catalyst, a known Ziegler type, Phillips type, or standard type catalyst, which is usually used in the production of olefins, is used.

The entire amount of circulating gas and the overflow amount of produced polymer are supplied to a cyclone 10 via a withdrawal nozzle 8 and piping 9. The produced polymer is separated into a receiver 11, and is intermittently pumped into the system by intermittent opening and closing of ball valves 12 and 13. be taken outside. The gas components separated by the cyclone are supplied to a cooler 14 and circulated to the polymerization apparatus by a gas circulation blower 15.

The apparatus of the present invention is significantly easier to manufacture than an apparatus in which the gas component supply section is located throughout the lower part of the polymerization apparatus, and is also more effective in preventing the formation of hot spots and block-like formations than in the case of using other conventionally known polymerization apparatuses. This method has the effect that a polymer having a moderate particle size distribution can be produced stably and economically for a long period of time with little polymer production.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view showing essential parts of the apparatus of the present invention, and FIG. 2 is a process diagram showing an example of polymerization of olefin using the apparatus of the present invention.

Claims (1)

[Claims] 1. An olefin in which a plurality of aperture groups each consisting of a plurality of apertures are dotted on the lower curved surface of the main body of a horizontal fluidized stirred bed polymerization apparatus, and a plurality of olefin supply chambers corresponding to each aperture group are provided below. Gas phase polymerization equipment.