This research demonstrates a novel vapour compression/absorption cascade refrigeration system for LNG liquefaction process to replace the air-cooled condenser equipped in Propane precooling refrigeration circuit, via either seawater or cooling towers to remove the heat rejected from precooling cycle of propane. The current investigation focuses on the novel configuration consists of ConocoPhillips optimised cascade cycle using three vapour compression refrigeration circuits which are Propane, Ethylene and Methane, besides one vapour absorption refrigeration cycle. The first aim of this paper is to perform thermodynamic analysis of LNG plant produces 50 kg/s of LNG. The second aim is to present a comparative parametric study for different number of stages which are 6, 7, 8 and 9 stages to evaluate and enhance the coefficients of performance of these design configurations. The results of design configurations for LNG plant conclude that number of stages has significant effects on both Coefficients of performance and the liquefaction efficiency. The Coefficients of performance is strengthened by using the design configurations consist of nine and eight compression stages. The coefficient of performance for vapour compression/absorption cascade for LNG plant can be slightly reduced rather than tradition vapour compression cascade cycles in LNG production from 0.741 to 0.704 for nine stages and from 0.838 to 0.709 for eight stages. The specific power consumptions in (kWhr/kg_LNG) can be optimized and adopted from 0.1875 to 0.225 kWhr/kg_LNG, for the highly recommended design configurations consist of nine and eight stages. The novelty of this study introduces economical and energy-analysis comparative studies to assess and optimize the performance of several design configurations for LNG plant regarding both economics and thermal performance. The conclusions can support the practical application.

本研究展示了一种用于 LNG 液化过程的新型蒸汽压缩/吸收级联制冷系统，以取代丙烷预冷制冷回路中配备的风冷冷凝器，通过海水或冷却塔去除丙烷预冷循环排出的热量。目前的研究重点是由康菲石油公司优化的级联循环组成的新型配置，除了一个蒸汽吸收制冷循环外，还使用三个蒸汽压缩制冷回路，即丙烷、乙烯和甲烷。本文的第一个目的是对生产 50 kg/s LNG 的 LNG 装置进行热力学分析。第二个目标是针对不同数量的阶段（6、7、8 和 9 阶段来评估和提高这些设计配置的性能系数。LNG 装置的设计配置结果表明，级数对性能系数和液化效率都有显着影响。通过使用由九个和八个压缩级组成的设计配置来增强性能系数。与传统的蒸汽压缩级联循环相比，LNG 工厂蒸汽压缩/吸收级联的性能系数可以略微降低，九级从 0.741 降低到 0.704，八级从 0.838 降低到 0.709。单位功耗（kWh/kg LNG 装置的设计配置结果表明，级数对性能系数和液化效率都有显着影响。通过使用由九个和八个压缩级组成的设计配置来增强性能系数。与传统的蒸汽压缩级联循环相比，LNG 工厂蒸汽压缩/吸收级联的性能系数可以略微降低，九级从 0.741 降低到 0.704，八级从 0.838 降低到 0.709。单位功耗（kWh/kg LNG 装置的设计配置结果表明，级数对性能系数和液化效率都有显着影响。通过使用由九个和八个压缩级组成的设计配置来增强性能系数。与传统的蒸汽压缩级联循环相比，LNG 工厂蒸汽压缩/吸收级联的性能系数可以略微降低，九级从 0.741 降低到 0.704，八级从 0.838 降低到 0.709。单位功耗（kWh/kg 与传统的蒸汽压缩级联循环相比，LNG 工厂蒸汽压缩/吸收级联的性能系数可以略微降低，九级从 0.741 降低到 0.704，八级从 0.838 降低到 0.709。单位功耗（kWh/kg 与传统的蒸汽压缩级联循环相比，LNG 工厂蒸汽压缩/吸收级联的性能系数可以略微降低，九级从 0.741 降低到 0.704，八级从 0.838 降低到 0.709。单位功耗（kWh/kg_LNG ) 可以从 0.1875 到 0.225 kWh/kg _{LNG 进行优化和采用，}强烈推荐的设计配置包括 9 级和 8 级。本研究的新颖之处在于引入了经济和能源分析比较研究，以评估和优化 LNG 工厂的几种设计配置在经济性和热性能方面的性能。结论可以支持实际应用。