FLNG小试、中试液化试验的放大性分析

Scaling effect analysis on FLNG laboratory and pilot liquefaction tests

FLNG(Floating Liquefied Natural Gas)液化工艺受规模、原料气组分及环境条件等影响较大,为了实现大规模工业化应用,基于南海某目标气田相关情况,建立丙烷预冷双氮膨胀液化工艺的FLNG小试及中试液化试验装置,并对试验结果进行FLNG放大过程的规律分析。结果表明:随着原料气处理规模的增大,丙烷预冷双氮膨胀液化工艺对原料气参数的敏感性变弱,且预冷段作用愈加明显,不仅可以降低装置能耗、氮气液化及过冷负荷,且可以减小氮气循环量,提高整体液化工艺的液化能力。在倾斜及晃荡工况下,冷箱内原料气温度变化不大,整个液化装置对晃动的适应性较强。液化工艺选择、设备选型、回收量对整个液化系统的液化率及液化能力的影响较大。随着液化规模的增大,高效的机组效率和合理的能量回收方式,在保证液化系统正常运行的同时,可以有效降低整个装置的能耗,提高经济效益。

The liquefaction process of floating liquefied natural gas(FLNG) is greatly sensitive to liquefaction capacity, components of feed gas and environmental conditions. To realize large-scale industrial application, it is necessary to carry out scale up experiment on liquefaction laboratory test and pilot test units. In this paper, the FLNG laboratory test and pilot test units for propane pre-cooling dual nitrogen expander liquefaction process were built, and the FLNG scale up performance in the tests was analyzed. It is shown that the propane pre-cooling dual nitrogen expander liquefaction process becomes less sensitive to the feed gas parameters and the effect of pre-cooling section becomes more visible, as the liquefaction capacity of feed gas increases, so that the energy consumption, nitrogen liquefaction and super-cooling load are cut down, and the amount of nitrogen circulation is reduced. Thus, the liquefaction capacity of the process is improved. In the tilting and sloshing conditions, the temperature of the feed gas in the cold box changes little and the whole liquefaction unit is highly adaptable to sloshing. Besides, the efficiency and capacity of the whole liquefaction system are greatly controlled by the selection of liquefaction process and equipment and the recovery amount. With the increasing of liquefaction capacity, efficient units and reasonable energy recovery modes can effectively reduce the energy consumption of the whole system while keeping the liquefaction system in normal operation, ultimately bringing about considerable economic benefits.