| 摘要 |
A process for polymerizing olefins at temperatures of from 30°C to 140°C and pressures of from 1.0 MPa to 10 MPa in the presence of a polymerization catalyst in a multistage polymerization of olefins in at least two serially connected gas-phase polymerization reactors, the process for transferring polyolefin particles from a first gas-phase polymerization reactor to a second gas-phase polymerization reactor comprising the steps of a) discharging polyolefin particles from the first gas-phase polymerization reactor into a separation chamber in which the polyolefin particles are separated from concomitantly discharged reaction gas, the separation chamber being at a lower pressure than the pressure in the first gas-phase polymerization reactor; b) transferring the polyolefin particles within the separation chamber into a lower part of the separation chamber which contains a bed of polyolefin particles which moves from top to bottom of this part of the separation chamber and into which a fluid is introduced in an amount that an upward stream of the fluid in the bed of polyolefin particles above the fluid introduction point is induced, c) withdrawing polyolefin particles from the lower end of said lower part and transferring them to one of at least two lock hoppers working intermittently in parallel; and d) simultaneously pressurizing another of the at least two lock hoppers working intermittently by means of a gas comprising reaction gas coming from the second gas-phase polymerization reactor, and apparatus for the multistage polymerization of olefins, comprising at least two serially connected gas-phase polymerization reactors and a device for transferring polyolefin particles from an up-stream gas-phase polymerization reactor to a downstream gas-phase polymerization reactor, the transferring device comprising - a gas/solid separation chamber placed downstream of the upstream gas-phase polymerization which gas/solid separation chamber is equipped at a lower part with an inlet for introducing a fluid, and - connected to the gas/solid separation chamber at least two lock hoppers, placed in a parallel arrangement, each connected to the downstream gas-phase polymerization reactor. |
