Process and apparatus for gas phase polymerization of olefins

Claim 1

A process for gas phase polymerization of olefins by the use of a catalyst subjected to a preliminary polymerization treatment, characterised by the following steps (a) to (f): (a) using as said catalyst subjected to a preliminary polymerization treatment, a catalyst having a density of 1.2 to 2.5 g /cm ; (b) feeding said catalyst subjected to a preliminary polymerization treatment, into a fluidized bed polymerization reaction vessel of which the main part has an inverted truncated cone shape with a ratio of the height to the diameter of the bottom part of the cone of 1:1 to 5:1 and an angle of the conical axis with the conical surface of 1 to 10°, has a vertical type agitator therein and has a distribution plate at the bottom part of the cone for forming a fluidized bed, and feeding an olefin gas, a mixed gas of an inert gas with the olefin or a circulating olefin gas, to the bottom part of the vessel to form a fluidized bed of the catalyst; (c) initiating polymerization of said olefin under agitation by means of said agitator, while maintaining a termperature inside the vessel of 30 to 130°C and a pressure of 0 to 50 k g/cm 2 G; (d) continuously feeding into the fluidized bed through dispersed injection ports a liquid organic quenching agent having a favourable latent heat of vaporization for offsetting at least almost all of the polymerization heat of said olefin; (e) continuously withdrawing from the top part of said polymerization vessel a mixed gas consisting of unpolymerized olefin gas, vaporized organic quenching agent and any inert gas; and (f) removing by liquefaction, most of said organic quenching agent from said mixed gas and feeding by circulation, the resulting olefin gas mixture to the above step (b).

Claim 6

An apparatus for gas phase polymerization of olefins, comprising: a fluidized bed polymerization reaction vessel (3) of which the main part has an inverted truncated cone shape with a ratio of the height of the cone to the diameter of the bottom part of the cone of 1:1 to 5:1 and an angle of the conical axis with the conical surface of 1 to 10°, has a vertical agitator (7) therein and has a distribution plate (2) for forming at the bottom part of the cone a fluidized bed; means (8) at the top part of said polymerization reaction vessel for withdrawing inert gas or unreacted gas or unreacted olefin; means (4,4') for feeding a catalyst subjected to a preliminary polymerization treatment and means for feeding a liquid organic quenching agent (5) for removing polymerization heat, both feeding means being at locations removed from the central to the top part of said vessel; and means (9) for withdrawing polyolefin at a location between the central part and bottom part of said vessel, but above the location of the distribution plate for forming a fluidized bed.

Claim 7

An apparatus for gas phase polymerization of olefins, comprising: a fluidized bed polymerization reaction vessel (3) of which the main part has an inverted truncated cone shape with a ratio of the height of the cone to the diameter of the bottom part of the cone of 1:1 to 5:1 and an angle of the conical axis with the conical surface of 1 to 10°, has a vertical agitator (7) therein and has a distribution plate (2) for forming at the bottom part of the cone a fluidized bed; means (8) at the top part of said polymerization reaction vessel for withdrawing inert gas or unreacted gas or unreacted olefin; means (4,4') for feeding a catalyst subjected to a preliminary polymerization treatment and means for feeding a liquid organic quenching agent (5) for removing polymerization heat, both feeding means being at locations removed from the central to the top part of said vessel; and means (9) for withdrawing polyolefin at a location between the central part and bottom part of said vessel, but above the location of the distribution plate for forming a fluidized bed.