a falling film of water is applied around the periphery of a fluid bed olefin polymerization reactor to cool the wall and reduce the temperature in the fluid bed near the inside surface of the wall . cooling has the effect of reducing static in the reactor , which in turn ameliorates a sheeting problem and can enhance production by facilitating control of the relation of the reactor temperature and the dew point of recycled gas . the process may be used concurrently with a gas cooling and condensing recycle system wherein at least some of the condensed recycle gas is injected in the vicinity of the internal wall surface .