Simulation And Optimization Of BOG Process In LNG Receiving Station

As a clean energy of high-quality, natural gas is awarded as the most preferred energy in the future for it produces high calorific value per unit and leaves little pollution. Liquefied Natural Gas (LNG), whose volume only amounts to1/625of standard one, is an effective form for storage, transportation and application. With the rapid development of national economy and further adjustment of energy structure, the demand of natural gas in China (especially in those highly-developed southeast coast due to the lack of pipeline but with high gas consumption) grows rapidly, which results in an urgent need of imported LNG. In this way, the construction of LNG terminals can help guarantee the security and stable supply of energy, in the meantime, playing a strategical role of modulating the peak.The system of LNG receiving terminal and BOG treatment were introduced in this assay. According to their characteristics, Aspen HYS YS V7.3was adopted as the main researching tool to analyze and study BOG recondensation and BOG reliquefaction.Firstly, this assay relied on HYSYS software, carrying out a simulating calculation of the typical recondenser process and thus gaining the Logistics parameters and performance parameters. Later on, this assay analyzed the process of LNG componsing, during which the respective influencing parameters (such as discharge pressure and the amount of BOG, the temperature and pressure of exporting gas etc.) of performance parameters in recondensation process (such as the power consumption of pumps and compressors, heat transfer equipments quantity, etc.) from the perspective of thermodynamics. Accordingly, suitable suggestions were made in operation. Lastly, an optimized model, which determined the constraints and aimed at deciding BOG compressor, in-tank pump, sendout pump and seawater pump, was set. What’s more, the mixed optimized method was adopted to calculates the optimized aim function and process parameters. In this way, the optimized process can be worked out to reduce consumption.After an extensive literature research, the author put forward a new kind of BOG treatment (namely BOG reliquefaction process):firstly identifing five BOG reliquefaction refrigerant campared with the common industrial ones; secondly carring out a contrast research of the four kinds and the five components of refrigerant, furthering assuring the later one and thus deciding the optimal formula in the first place; thirdly calculating the main process parameters and function parameters by HYSYS; fourthly, optimizing the ratio of the hybrid refrigeration cycle cooling and the voltage to save energy; lastly, analyzing the optimized process, finding out the defects in energy consumption and thus proposing an apropriate method to improve.