Patent ID: 7329712

Claim:
A method for controlling swelling in an olefin polymerization loop reactor system comprising: a) introducing an olefin, a polymerization catalyst, and a diluent carrier liquid into a loop reactor, having an internal circulation pump; b) supplying power to said circulating pump to circulate said diluent liquid and said olefin through said loop reactor while polymerizing said olefin monomer in the presence of said catalyst system to produce a slurry of polymer particles in said carrier liquid; c) diverting the flow of said slurry through said loop reactor into at least one settling leg connected to the loop reactor and sequentially discharging polymer particles in the settled slurry from said at least one settling leg to withdraw said polymer particles from said reactor system; and d) measuring a plant control parameter which displays a progressively increasing level of fluctuation at the onset of swelling characterized by an instability in said polymerization process which results in fluctuations in the measured parameter which progressively increases with time; e) processing a signal representative of the sensed parameter measurement in real time in order to detect the onset of swelling; and f) in response to the detection of the onset of swelling, adding a diluent to said reactor to dilute the circulating slurry of polymer particles in said diluent carrier liquid in order to alleviate said swelling condition.