Polyolefin production using condensing mode in fluidized beds, with liquid phase enrichment and bed injection

This invention relates to gas phase exothermic reactions to make particulate product in fluidized bed reactors. The invention is described with respect to olefin polymerization but is not limited to the production of polymeric products; rather, it may be practiced in connection with any exothermic reaction which is carried out in a gas fluidized bed with external cooling. It relates particularly to improvements in the condensing mode of operation in which a portion of the fluidizing gas or fluid is withdrawn from the reactor, cooled to remove the heat of reaction, partially condensed, and recycled back to the fluidized bed reactor. In the present invention, the recycle is effected by splitting the recycle stream in at least two streams directed to different areas of the reactor. The partially condensed fluid recycle stream of a fluidized bed polyolefin reactor operating in the condensing mode is split into two portions by a stream splitter. In a preferred mode, the smaller stream from the splitter contains a higher ratio of liquid to gas than the larger stream. One portion of the split stream is injected below the fluidized bed and the other, preferably with enhanced liquid content, is injected into the fluidized bed at a level above the distributor plate, preferably above the product withdrawal level.