Patent ID: 6897268
Filing Date: 2005-05-24
Classification: B01J,C08F,Y10S

Abstract:
1. In a fluidized bed polymerization process wherein an olefin is polymerized under polymerization conditions, the improvement comprising polymerizing said olefin and a solid catalyst in a fluidized bed polymerization vessel having a fluidized bed for polymerization of said olefin, whereby said bed is fluidized by an olefin-containing fluid gas introduced into said polymerization vessel; recovering a gas containing unreacted olefins from the top of said fluidized bed polymerization vessel, and recycling said gas containing unreacted olefins to said polymerization vessel, and controlling the velocity at which said unreacted olefins are recycled; feeding fresh olefin-containing gas to said fluidized bed polymerization vessel; feeding solid catalyst into said fluidized bed polymerization vessel; monitoring the temperature or temperature distribution of said fluidized bed in said polymerization vessel by means of temperature measuring devices installed on the external wall surface of said fluidized bed polymerization vessel and arranged at plural different positions away from each other longitudinally and laterally, wherein at least one of the temperature measuring devices is installed on the external wall surface of said fluidizing bed polymerization vessel and formed on the polymerization vessel to produce no protrusion on the inner wall surface of the vessel; comparing the measured values of temperature or temperature distribution with a target value of temperature or temperature distribution, and modifying the conditions of polymerization to obtain a measured value of temperature or temperature distribution that at least substantially corresponds to said target value in response to said comparison.