Process for the preparation of a polyolefin in a reaction system from one or more α-olefin monomers of which at least one is ethylene or propylene, wherein the reaction system comprises a reactor, a product purge bin, a granular feed bin, wherein the granular feed bin is located downstream of the product purge bin, a recovery unit and an extrusion unit directly coupled to the granular fed bin, wherein the reactor comprises a fluidized bed, an expanded section located at or near the top of the reactor, a distribution plate located at the lower part of the reactor and an inlet for a recycle stream located under the distribution plate, wherein the process comprises a) feeding a polymerization catalyst to the fluidized bed in the area above the distribution plate, b) feeding the one or more α-olefin monomers to the reactor, c) circulating fluids from the top of the reactor to the bottom of the reactor, wherein the circulating fluids are cooled using a heat exchanger, resulting in a cooled recycle stream comprising liquid, and wherein the cooled recycle stream is introduced into the reactor using the inlet for the recycle stream, d) withdrawing a stream comprising the polyolefin and fluids from the reactor and passing said stream into the product purge bin, e) purging the product purge bin with a purge stream comprising a first inert gas, preferably nitrogen and steam such that a stream comprising a purged polyolefin and a stream comprising fluids, wherein the stream comprising the fluids is substantially free of steam, is obtained, f) introducing at least part of the stream comprising the fluids back into the reactor via the recovery unit, g) introducing the stream comprising the purged polyolefin into the granular feed bin and h) contacting a deactivating stream comprising steam with the purged polyolefin in the granular feed bin to obtain a polyolefin that is substantially free of active polymerization catalyst. a) feeding a polymerization catalyst to the fluidized bed in the area above the distribution plate, b) feeding the one or more α-olefin monomers to the reactor, c) circulating fluids from the top of the reactor to the bottom of the reactor, wherein the circulating fluids are cooled using a heat exchanger, resulting in a cooled recycle stream comprising liquid, and wherein the cooled recycle stream is introduced into the reactor using the inlet for the recycle stream, d) withdrawing a stream comprising the polyolefin and fluids from the reactor and passing said stream into the product purge bin, e) purging the product purge bin with a purge stream comprising a first inert gas, preferably nitrogen and steam such that a stream comprising a purged polyolefin and a stream comprising fluids, wherein the stream comprising the fluids is substantially free of steam, is obtained, f) introducing at least part of the stream comprising the fluids back into the reactor via the recovery unit, g) introducing the stream comprising the purged polyolefin into the granular feed bin and h) contacting a deactivating stream comprising steam with the purged polyolefin in the granular feed bin to obtain a polyolefin that is substantially free of active polymerization catalyst.