一种评价天然气液化工艺技术先进性的新方法

Method for advancement evaluation of natural gas liquefaction process

国内外针对大型天然气液化工艺技术开展的能耗对比研究存在结论不一致的问题,主要原因在于流程模拟的优化程度与工艺参数选取不同,且流程模型缺乏验证。通过分析影响天然气液化能耗的工艺技术因素和自然条件因素,指出采用液化能耗作为LNG工艺评价指标必须以自然条件相同为前提,而液化效率定义为理论液化功与实际液化功之比,自然条件因素由理论液化功体现,从而液化效率直接反映工艺技术的性能表现。利用LNG工厂的运行数据进行工艺计算,通过对比实际液化效率的方法来衡量不同液化工艺技术的先进性,避免了流程模拟方法存在的可靠性问题。对全球不同地区的13座LNG工厂应用液化效率评价方法,结果表明:C3MR流程在低温环境下性能明显下降,DMR流程则显示出更强的适应性与操作灵活性,而级联流程相比其他液化工艺流程液化效率较低。

The conclusions of energy consumption studies for different large natural gas liquefaction processes seem inconsistent,the main reasons including： different degree on process optimization,different process parameters and lack of model validation. Both technology and natural factors affecting energy consumption for natural gas liquefaction were analyzed,and the same natural factors were pointed out as a precondition when using energy consumption as an evaluation index,while the exergy efficiency was defined as the ratio of ideal and practical liquefaction work,the differences in natural conditions were related by the ideal liquefaction work,the exergy efficiency value directly reflected the performance of liquefaction process. So the LNG plant operating data can be used for actual liquefaction exergy efficient calculation to measure the rate of technological advancement,and avoid the reliability problems of process simulation. The exergy efficiency evaluation method was used for the evaluation of13 LNG plants worldwide. The results suggest that the C3 MR process shows performance degradation in a lowtemperature environment,however,the DMR process exhibits greater adaptability and flexibility in operation,and the cascade process has lower liquefaction efficiency compared to other liquefaction processes.