Process

A process for the production of a polyolefin, which process comprises:

• a. reacting one or more olefins in a polymerisation reactor to produce a polyolefin,
• b. withdrawing a polymerisation effluent stream comprising polyolefin solids,
• c. passing the effluent from the effluent stream to a first degassing vessel in which the polyolefins solids are degassed, said first degassing vessel operating at a pressure, P1,
• d. opening a solids inlet of a connecting vessel and passing the polyolefin solids from the first degassing vessel to the connecting vessel via the solids inlet and until there is collected in the connecting vessel a volume of polyolefin solids, and wherein, once the volume of polyolefin solids has been collected:
• i. the solids inlet of the connecting vessel is closed,
• ii. the pressure in the connecting vessel is reduced to a pressure, P2, via a vent line of the connecting vessel,
• iii. after the pressure is reduced, a solids outlet of the connecting vessel is opened and the polyolefin solids are passed to a second degassing vessel via the solids outlet, and
• iv. after passing the polyolefin solids to the second degassing vessel, the solids outlet is closed,
• e. degassing the polyolefin solids in the second degassing vessel, the second degassing vessel operating at a pressure, P3, wherein
• i. the volume of polyolefin solids collected in step (d) prior to steps (i)-(iv) is at least 50% of a volume of the connecting vessel,
• ii. P2 is at least 20% lower than the pressure, P1,
• iii. the connecting vessel has a cylindrical body, with a top section connected to a top of the cylindrical body and a bottom section connected to a bottom of the cylindrical body, wherein the cylindrical body has an H/D of less than 2, H being a height of the vessel and D being a diameter, and
• iv. the vent line is located on the top section of the connecting vessel or on an upper part of the cylindrical body of the connecting vessel, but above the collected volume of solids.