Study On Recovery Scheme For BOG In The Small-scale LNG Receiving Station

Liqufied natural gas(LNG)receiving station is the terminal that receive,store and vaporize LNG.Thus,it can supply the users with natural gas whenever the user needed.With the characteristics of small construction scale,low use frequency and low investment,the small-scale LNG receiving station will play an important role in the national energy reserve strategy,especially considering the gas famine in winter.LNG vaporizes into boil off gas(BOG)in the process of transportation and storage in LNG receiving station.The production of BOG not only causes huge economic losses for enterprises,but induces dangerous for LNG receiving station as well.How to hundle the BOG is a serious question for small-scale LNG receiving station.Based on the project of the small-scale LNG receiving station in a city,this paper introduces the process flow and control principle of small-scale LNG receiving station,gives the static calculation model of BOG production of different process equipment and facilities,and calculates the BOG production under five different operating conditions.According to the load characteristics of the city gas network around the small-scale LNG receiving station,this paper analyzes the acceptance capacity of high and medium pressure city gas network to accept BOG,and determines the BOG export scheme of the small-scale LNG receiving station.The energy consumption of the BOG direct compression,reco ndensation and reliquefaction recovery process is modeled,and the energy consumption of the three BOG treatment process in the small-scale LNG receiving station is analyzed.Combined with the analysis of the amount of BOG produced and the gas consumption law of the surrounding city gasnetwork,it is determined that the BOG treatment process of the small-scale LNG receiving station is the direct compression recovery process.Taking the minimum operation energy consumption as the optimization objective,the optimization model of BOG direct compression export process system of the small-scale LNG receiving station is established,and the particle swarm optimization algorithm is used for optimization.Finally,the optimal combination of flow distribution and compressor parameter setting is obtained,which is about 8.31%lower than the process energy consumption before optimization.The results of this paper will supply some help for the similar small-scale LNG receiving station.