Process and a multi-stage reactor assembly for the production of polyolefins

A multi-stage reactor assembly for the production of polyolefins comprising

• a) at least one loop reactor, comprising:
• at least one inlet for feeding a slurry comprising at least one polymerization catalyst, at least one carrier liquid, first monomer(s) and optionally at least one first comonomer;
• at least one outlet for withdrawing a first polyolefin produced in the at least one loop reactor;
• and
• b) at least one gas-solids olefin polymerization reactor comprising:
• a top zone (1);
• a middle zone (2), which comprises a top end in direct contact with said top zone (1) and which is located below said top zone (1), the middle zone (2) having a generally cylindrical shape;
• and
• a bottom zone (3), which is in direct contact with a bottom end of the middle zone (2) and which is located below said middle zone (2);
• one or more jet gas feeding ports (5) located in a jet gas feeding area of the middle zone (2);
• a first line (6) for feeding a fluidization gas (FG) stream into the bottom zone (3) of the at least one gas-solids olefin polymerization reactor,
• a second line (7) for withdrawing a stream comprising fluidization gas from the top zone (1) of the at least one gas-solids olefin polymerization reactor,
• a third line (8) for introducing a jet gas (JG) stream into the middle zone (2) of the at least one gas-solids olefin polymerization reactor via the one or more feeding ports (5), wherein the jet gas (JG) stream fed through at least one of the one or more jet gas feeding ports (5) is provided by a flash pipe (FP) from the loop reactor;
• a feeding port (9) connected to the at least one outlet of the at least one loop reactor, for feeding catalyst, polyolefin, monomer and optionally comonomer;
• and
• a polymer withdrawal outlet (10) for withdrawing a second polyolefin produced in the at least one gas-solids olefin polymerization reactor;
• one or more flash pipe jet gas feeding ports (14) located in a jet gas feeding area of the middle zone (2);
• and
• a sixth line (15) for introducing a flash pipe (FP) gas stream into the middle zone (2) of the at least one gas-solids olefin polymerization reactor via the one or more flash pipe jet gas feeding ports (14).