Systems for polymer fines recovery

A gas-phase polymerization system comprising:

• a fluidized bed reactor comprising a reactor feed inlet and a fluidizing gas outlet;
• a cyclone separator coupled to (and in fluid communication with) the fluidizing gas outlet and configured to receive a fluidizing gas comprising polymer fines and separate the polymer fines from the fluidizing gas;
• a venturi eductor coupled between the cyclone separator and the fluidized bed reactor and configured to receive the separated polymer fines from the cyclone separator;
• and
• a fines return line coupling the venturi eductor to the fluidized bed reactor and configured to return the separated polymer fines from the venturi eductor to the fluidized bed reactor;
• wherein the fluidized bed reactor further comprises a grid plate above the reactor feed inlet, a reaction zone above the grid plate, and a disengagement zone above the reaction zone and having a larger diameter than the reaction zone;
• wherein the fines return line has a reactor entry nozzle coupled to the fluidized bed reactor at a height above a top of the grid plate that is at least 50% of a height (H) of the fluidized bed measured from the top of the grid plate and a top of a fluidized bed;
• and
• wherein the following conditions are met:
• (a) the reactor entry nozzle of the fines return line is coupled to the fluidized bed reactor at an angle alpha (α)≥5° relative to a vertical axis of the reaction zone;
• or
• (b) the reactor entry nozzle of the fines return line is coupled to the fluidized bed reactor at an angle beta (β)≥5° relative to a vertical plane that includes a vertical axis of the fluidized bed reactor and an entry point of the reactor entry nozzle of the fines return line into the fluidized bed reactor;
• or
• (c) both conditions (a) and (b) are met.