Patent ID: 6759489
Filing Date: 2004-07-06
Classification: C08F

Abstract:
A continuous gas fluidized bed method for making a polymer featuring a condensing agent in a recycle stream comprising:continuously passing a gaseous stream comprising monomer and the condensing agent through a fluidized bed in a reaction zone having a controlled reactor bed temperature, a lower fluidized bed density, an upper fluidized bed density and a plurality of measuring siten temperatures, in the presence of catalyst; withdrawing from the reaction zone polymer product and a stream comprising unreacted gases; recycling the stream into the reaction zone with sufficient additional monomer to replace monomer polymerized and withdrawn as polymer product; cooling the recycle stream to condense a portion thereof and form a liquid-containing mixture having a recycle stream dew point temperature, a reactor inlet temperature and comprising from about 17.5% to about 70% liquid by weight based on the total weight of the cooled recycle stream wherein the difference between the controlled reactor bed temperature and the recycle stream dew point temperature of the mixture is greater than or equal to about 5Â° C.; and introducing the mixture into the reaction zone wherein the liquid in the mixture is vaporized; wherein &Dgr;&rgr; satisfies the condition 0 kg/m3&lE;&Dgr;&rgr;<70 kg/m3 and, when &Dgr;&rgr;&gE;10 kg/m3, simultaneously, at least a critical number of An satisfy the condition 0.25&lE;An<0.8; and wherein &Dgr;&rgr; is equal to the (lower fluidized bed density) minus the (upper fluidized bed density) and An=(controlled&it;â€ƒ&it;reactor&it;â€ƒ&it;bed&it;â€ƒ&it;temperature)-&NewLine;&it;â€ƒ&it;(measuring&it;â€ƒ&it;siten&it;â€ƒ&it;temperature)(controlled&it;â€ƒ&it;reactor&it;â€ƒ&it;bed&it;â€ƒ&it;temperature)-&NewLine;&it;â€ƒ&it;(reactor&it;â€ƒ&it;inlet&it;â€ƒ&it;temperature).