回收LNG冷能的新型碳二烃两级膨胀朗肯循环

A novel two - stage expansion C2 Rankine cycle with LNG cold recovery

提出了一种新型的回收LNG冷能的两级膨胀朗肯动力循环,可以乙烯或乙烷作为工质。此工艺流程采用多股流低温板翅式换热器(MSCHE)作为主要设备,使工质两级膨胀并采用回热过程,可以使循环的冷能利用效率得到明显提高。针对此工艺分别以乙烯或乙烷为工质,与LNG直接膨胀结合和不结合,共四种方案采用HYSYS软件进行工艺模拟,并对模拟结果进行了比较和分析,可得出无LNG膨胀的乙烯两级膨胀工艺流程最为合理,其冷能和火用的利用率可以分别达到19.67%和21.75%。

A novel two - stage expansion Rankine power cycle of ethylene or ethane that could recover cold energy of LNG was represented. A core device of multi - stream cryogenic heat exchanger （MSCHE） was conducted in the cycle to decrease the temperature difference of heat transfer process and increase the energy efficiency. The applications of two - stage expansion and heat recovery process in the cycle obviously increased the cold recovery efficiency. The total 4 schemes which used ethylene or ethane as work fluids, with and without LNG direct expansion process were simulated using HYSYS software. The results show that the two - stage expansion ethylene Rankine cycle without LNG direct expansion is the most reasonable cycle. The cold energy and exergy efficiency of the cycle is 19.67% and 27.15% respectively.