气相法聚丙烯装置排放气回收系统排放至火炬系统的尾气含有大量烃类和氮气，应用膜分离和深冷分离组合技术高效回收尾气中的乙烯、丙烯和氮气等组分，减少火炬排放，降低装置物耗和能耗。实际应用效果显著，总烃回收率达到92%以上，氮气回收率75%，聚丙烯装置废气排放量减少2 591 t/a，平均能耗下降0.24 kg/t，实现了节能降耗和清洁生产的目的。

There are a lot of hydrocarbons and nitrogen in the vent gas discharged to flare system from gas recovery system in gas-phase polypropylene plant.In order to recover ethylene,propylene and nitrogen from the vent gas,reduce discharge to the flare system and cut down the consumption of materials and energy,a membrane-cryogenic hybrid separation technology is applied.Since the technology is applied in the recovery system,the total hydrocarbons recovery rate exceeds 92 wt% and the recovery rate of nitrogen reaches 75 wt%.Results show that the average energy consumption of polypropylene plant decreases by 0.24 kg standard oil per ton of polypropylene and reduces the discharging amount of vent gas to flare by 2 591 t/a,reaching the purpose of energy conservation and emission reduction.