Research On Process Optimization Of LNG Receiving Station

LNG(Liquefied Nature Gas)has a growing proportion of energy consumption due to its clean and efficient characteristics,and plays an important role in the development of clean energy and low carbon consumption.Due to leakage of pipelines and equipment,volume replacement of LNG unloading and external transport,flashing,a large amount of boil-off gas(BOG)flows into the storage tank.The treatment of BOG will consume a lot of financial resources at the receiving station.The improvemont of the receiving station unloading and BOG processing will bring considerable economic benefits to the receiving station.The composition of the power consumption of the receiving station unloading process system is analyzed,and the five main factors affecting the power consumption of the receiving station are summarized:cold storage circulating flow,branch flow,ambient temperature,unloading cycle,unloading temperature,established by using HYSYS software.The dynamic simulation model of the unloading process system simulates the unloading process of the LNG receiving station under different working conditions,calculates the generated power consumption,and derives the optimal operating variables.The results show:the total power consumption of the receiving station increases with the increase of the power consumption of the low-pressure pump,and the optimal cooling flow rate is 160 m~3/h;the power consumption of the low-pressure pump increases,and the compressor and total power consumption decrease during the discharge stage;the higher the temperature,the more obvious the influence of the cooling circulation flow rate on the total power consumption of the receiving station;the higher the unloading temperature,the higher the total power consumption of the receiving station;when the branch flow increases,the total power consumption of the receiving station increases,the best branch flow is 25m~3/h.Through the material ratio,BOG amount in the receiving station and the output of the receiving station,the working condition of the high pressure compressor is analyzed,and the steady state model of the BOG processing at the receiving station is established.Combined with the dynamic model of the unloading process,the different cooling cycles under a given external output are simulated.The power consumption generated by the flow rate obtains the optimal cold storage cycle operation scheme under the external output.The results show that when the external output is 100%,the total power consumption is minimum when the cold storage circulating flow rate is 158m~3/h;the external output is 34.5%;when the external output is 100%,the total power consumption is the smallest when the cooling flow rate is 236 m3/h;when the external output is 25%,the total power consumption is the smallest when the cooling circulation flow rate is 275 m~3/h.Taking the operating conditions of Jiangsu LNG receiving station in June as an example,the unloading process system of the receiving station is optimized.The results show that the optimal cooling flow rate is 160 m~3/h under this condition,the optimal branch flow is 25 m~3/h,and total annual power consumption can be saved up to 17%.In the BOG processing system model,the external transport volume of jiangsu LNG receiving station in early may was brought in to obtain the optimal cooling cycle flow,which can save up to 8.11%of the total annual power consumption after optimization.