Patent ID: 7652109

Claim:
Process for the gas-phase (co-) polymerisation of olefins in the presence of a catalyst in a fluidized bed or sub-fluidised bed reactor system comprising the reactor, a recycle line connecting the top of the reactor to its bottom and a cyclone, the cyclone inlet being connected to the top of the reactor and the cyclone outlet being connected back to the reactor at a lower elevation, the process comprising: keeping polymer particles that are being formed in a fluidised or sub-fluidised state by means of a gaseous reaction mixture traveling as an ascending stream in the reactor, recycling the gas mixture leaving via the top of the reactor to the base of the reactor by means of the recycle line, passing at least part of said gas mixture leaving the top of the reactor through at least one cyclone in order to separate the gas from the fine particles, recovering the fine particles from the bottom of the cyclone, recycling the fine particles back to the reactor, and adding a flowability improver additive at a location comprised between the top of the reactor and the cyclone entry.