Analysis on abnormal working conditions of LNG cold box based on grey system theory

Author of the article:GUO Haixin

Author's Workplace：Kunlun Energy Hubei Huanggang LNG Co., Ltd., Huanggang, Hubei, 438000, China

Key Words：LNG cold-box; Refrigerant piping; Blockage due to freezing; Grey system theory; Effectiveness

Abstract：To guarantee the LNG product quality and prevent unexpected shut-down, this study focuses on the problem of coil tube blockage caused by the large pressure differential along the LNG cold box refrigerant piping. Based on the data of real time temperature control points and the application of grey system theory, this research developed simulation model and simulated the mixing ratio of system refrigerant components that match the performance of real time condition. The simulation model could also regulate the refrigerant components ratio on real time basis using the simulated data. The research shows that the grey system theory and calculation method 1) can identify problems in actual conditions by calculation;2) with existing data, this theory and calculated method can identify the pros and cons of different refrigerant components ratio over actual real time working conditions;3) can provide guidance and verification for future adjustment, rectifying the issues on the inability to analyse the real time performance of different refrigerants mixing ratio due to a lack of analysing equipment and related infrastructure. The research findings can be used as a reference for selection of optimum refrigerant mix and production operation control of plate-fin heat exchangers.