Patent ID: 9133291
Filing Date: 2015-09-15
Classification: C08F

Abstract:
1. A process for transferring polyolefin particles from a first gas-phase polymerization reactor to a second gas-phase polymerization reactor in a multistage polymerization of olefins carried out in at least two serially connected gas-phase polymerization reactors, wherein the first gas-phase reactor is a fluidized-bed reactor comprising a gas distribution grid and a settling pipe, which is integrated with its upper opening into the distribution grid and contains a bed of polyolefin particles which moves from top to bottom of the settling pipe, the process comprising the steps of introducing a fluid into the settling pipe in an amount that an upward stream of the fluid is induced in the bed of polyolefin particles above the fluid introduction point; withdrawing polyolefin particles from the lower end of the settling pipe; and transferring the withdrawn polyolefin particles into the second gas-phase polymerization reactor.