炼油厂干气轻烃分离与LNG冷能利用的集成

Light Hydrocarbons Separation Process in Refinery by Using LNG Cold Energy

中国乙烯装置原料以石脑油等重质原料为主,而原料越重,乙烯成本也就越高。从炼油厂干气中回收轻烃组分可以为乙烯装置提供优质原料,从而能降低乙烯成本,但是轻烃深冷分离工艺中压缩制冷系统能耗很高。液化天然气(LNG)气化过程中释放大量的冷能。为了降低深冷分离所需压缩能耗,以中国国内某炼油化工厂为研究对象,将LNG冷能用于炼油厂干气深冷分离工艺,取代三机压缩制冷系统。结果表明,利用82.0t/h的LNG可替代原工艺约14373kW的冷量负荷,节省约7973kW的冷剂压缩制冷系统功耗,大幅度降低炼油厂干气深冷分离装置的能耗成本。

Naphtha is the dominant feedstock for ethylene plants in China. The heavier the feedstock is, the higher the production cost of ethylene is. Consequently, the recovery of light hydrocarbons from refinery gas can bring great economic and social benefits, however, the process of light hydrocarbons cryogenic separation is energy-intensive, when it comes to compression refrigeration. Liquefied natural gas（LNG） should be vaporized before being supplied to the final consumers at the receiving terminals, and a lot of high-grade cold energy will be released during the vaporization process, which should be utilized effectively. Regarding a domestic refinery as the research object, the LNG cold energy was used to displace compression refrigeration system in cryogenic separation process. As a result, 82.0 t/h LNG can provide 14373 kW cold energy for the separation process, saving 7973 kW compression power to greatly cut the cost of the process.