JPH0442404B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gas distribution plate used in a fluidized bed polymerization tank or a stirred fluidized bed polymerization tank of a gas phase polymerization apparatus, particularly a polymerization apparatus suitable for gas phase polymerization of olefins.

In addition, the terms "polymerization" and "polymer" used in this specification are used to include "homopolymerization", "copolymerization", "homopolymer", and "copolymer", respectively. .

In recent years, improvements in transition metal catalysts for olefin polymerization have dramatically improved the production capacity of olefin polymers per unit transition metal, and as a result, it has become possible to omit the catalyst removal operation after polymerization.

When such highly active catalysts are used, a method is generally adopted in which olefin polymerization is carried out in the gas phase because it is the simplest to operate after polymerization. In such gas phase polymerization, a fluidized bed polymerization tank is usually used in order to smoothly proceed with the polymerization, and the olefin or olefin-containing gas introduced from the bottom of the polymerization tank through an introduction pipe is uniformly dispersed by a gas distribution plate. The olefin polymer rises and flows together with solid particles consisting of the olefin polymer and catalyst particles in the fluidized bed, and polymerization is carried out.

At this time, if the pore size of the gas distribution plate is small, the pores are likely to become clogged due to adhesion of generated polymer particles, and if the pore size is large, the polymer particles tend to fall under the gas distribution plate. , it tends to stick to the wall or form lumps under the gas distribution plate.

The latter drawback can be overcome to some extent by attaching a cap over the hole in the gas distribution plate, but one of the points that must be taken into consideration when attaching the cap is that the gas does not reach the wall of the polymerization tank. The aim is to ensure that the area is sufficiently sprayed. Therefore, as shown in Figure 1, in the cap near the wall, one of the left and right gas outflow openings is directed toward the wall, but most of the gas supplied from the holes in the gas distribution plate is directed to the other side, that is, inward in the radial direction. As a result, the flow near the wall stagnates and the polymer particles tend to form agglomerates in that area, which can even lead to blockage of the wall opening. It was easy.

In order to solve these problems, the present invention divides the cap near the wall surface with a partition wall in the middle and arranges the holes of the gas distribution plate on both sides of the cap, or alternatively, the partition wall is formed to cut through the hole vertically, and the cap is This ensures that the ejected gas flows out through the opening on the wall side.

To explain the following with reference to the drawings, FIG. 1 shows an example of a gas distribution plate 3 attached to the lower part of a polymerization tank (not shown) and with a cap 2 attached above the hole 1. In addition to having a triangular, semicircular, or other arbitrary cross-sectional shape, the caps are arranged in a staggered manner so that the gas flowing out from the openings 4 on both sides is distributed evenly and evenly to all parts of the gas distribution plate, with the caps on the periphery being on one side. opening 4
1 faces outward so that the gas can also be blown onto the inner wall surface of the polymerization tank.

As described above, in the peripheral cap 2 in which one opening 41 faces outward, the middle part is partitioned by a partition wall 5, and holes 10 and 1 are formed on both sides of the cap 2, respectively.
1, the hole 11 leading to the outward opening 41 is preferably made larger in diameter than the other hole 10 (FIG. 2) so that a sufficient amount of gas can flow out through it. ing.

FIG. 3 shows another embodiment, in which the peripheral hole 1 is formed into a relatively large diameter, preferably an oval shape, and the partition wall 7
The hole 1 is preferably provided inwardly so as to straddle the hole 1.

According to the present invention, gas flows out more reliably through the outward opening of the cap provided at the peripheral edge, and agglomeration of polymer particles near the wall surface is eliminated.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a gas distribution plate with a cap attached over the hole, FIG. 2 is an enlarged plan view of the peripheral edge of the cap, and FIG. 3 is an enlarged plan view of another embodiment. 1... Hole, 2... Cap, 3... Gas distribution plate, 4... Opening, 5, 7... Partition wall, 10, 11
...hole, 41...opening.

Claims (1)

[Scope of Claims] 1. Among the caps attached to the holes through which the gas of the gas distribution plate disperses and flows out, the peripheral cap is arranged such that one of the openings provided on both sides faces outward, and In a gas dispersion plate provided in a polymerization tank in a gas phase polymerization apparatus designed to cause gas to flow out toward the wall surface of the polymerization tank, a peripheral cap 2 is partitioned at an intermediate part by partition walls 5 and 7, The holes 1, 10, 11 of the gas distribution plate 3 are formed on both sides of the partition wall or the partition wall 7
A gas distribution plate that is divided into left and right sides. 2. The gas distribution plate according to claim 1, wherein the holes communicating with the outward openings 41 are larger than the holes communicating with the inward openings.