| 摘要 |
The present invention relates to the purging of propane in a polypropylene manufacturing process comprising, a) polymerizing propylene in a polymerization zone, b) withdrawing from said polymerization zone an effluent comprising polypropylene, propylene, propane and optionally a solvent, c) sending said effluent to a separation zone thereby producing polypropylene, optionally the solvent and a stream comprising propylene and propane, d) optionally recycling the solvent to the polymerization zone, e) sending said propylene and propane stream to a splitter thereby producing an overhead consisting essentially of propylene recycled to the polymerization zone and a rich propane bottom stream comprising a minor part of propylene, f) sending the bottom stream to a membrane separation zone thereby producing a permeate having an enhanced propylene content and a reduced propane content and a purge having an enhanced propane content and a reduced propylene content, g) recycling the permeate to the polymerization zone. In an embodiment the bottom stream produced in the splitter of stepe) is washed in a scrubber to remove contaminants and the overhead of said scrubber is sent to the membrane separation zone. The present invention is also the debottlenecking of a polypropylene manufacturing facility comprising, a polymerization zone, a separation zone to recover the polypropylene, optionally the solvent and a stream comprising propylene and propane and a splitter to separate propane and propylene, wherein, a membrane separation zone is provided, said membrane separation zone is fed with the splitter bottom thereby producing a purge and a permeate recycled to the polymerization zone. In an embodiment a scrubber is inserted between the splitter bottoms and the membrane separation zone stream to wash the splitter bottom stream to remove contaminants and the overhead of said scrubber is sent to the membrane separation zone. |
