a method and apparatus are disclosed for metering the removal of polymer or copolymer from the take - off end of a horizontal vapor phase polymerization stirred - bed reactor . the take - off zone discharge apparatus comprises a drain valve , which can seal off the reactor when needed , followed by an automatic discharge ball valve , which controls the discharge of product from the reactor . the discharge apparatus limits vapor losses , outlet pluggage , and downtime on the reactor . the discharge apparatus also can be operated for allowing residence time flexibility , increased catalyst yields , and improved product quality .