双膨胀自深冷分离技术应用于PP装置尾气回收

Application of Double-expansion Self-cryogenic Separation Technology in Vent Gas Recovery of Polypropylene Plant

聚丙烯装置排放气的回收方法主要有压缩冷凝、膜分离、变压吸附等。目前应用最为广泛的是压缩冷凝加膜分离技术,但是由于膜分离技术的选择性较低,因此其运行能耗较高。而采用双膨胀自深冷分离技术后,由于返回至压缩机入口的气体近于纯烃类物质,从而避免了大量的氮气反复升压、降压。因此,在相同回收率及回收纯度的要求下,压缩机能耗至少降低约40%,具有良好的经济效益。

The vent gas recovery technologies of polypropylene plant mainly include compression condensation,membrane separation,and pressure swing adsorption.The compression condensation plus membrane separation is the most widely used technology.However,due to the low selectivity of membrane separation technology,its operating energy consumption is relatively high.In the case of double-expansion self-cryogenic separation technology,the gas returned to the compressor inlet is almost pure hydrocarbons,which prevents a large amount of nitrogen from repeatedly increasing and decreasing pressure.Under the requirements of the same recovery rate and purity,the operating energy consumption of compressor can be reduced by at least 40%,which brings more economic benefits.