Optimization Design And Engineering Of The High-pressure Natural Gas Transmission System Emergency Reserve Process

Natural gas consumption and import quantum are huge in China, but at the same time, itis highly dependent on foreign gas supply and easily affected by the season, coupled withthe natural gas transportation in China mainly use high pressure pipeline, which is easilyinfluenced by the distance, topography,and so on.Thus makes the ability of our natural gastransmission system to deal with emergencies and natural disaster low, and it isdisadvantageous to the overall development of China’s natural gas industry. Therefore, settingup emergency reserves of natural gas storage,which has strategic significance, is particularlyimportant. However, storage technology is a process of energy consumption, especially thenatural gas liquefaction process. While a lot of pressure energy is wasted in regulator stationssurrounding the natural gas reserve station during pressure regulating. So if the pipe networkpressure can be used to storage technology with high energy consumption, it will not onlyreduce the amount of energy consumption, creating economic benefits, but have an importantimpact on the work of deepening energy-saving emission reduction in China.By comparing the existing natural gas reserves the basic process,a complete set ofreserve process is put forward in this paper. According to the setting of regulator stations, thepressure power is used to optimize reserve process, in which the produced mechanical energyis used for power generation and the cold produced is used to precool natural gas ofliquefaction process in the reserve storage. Taking the secondary regulating specifications ofsecond line of Gas Transmitting From West to East Project as the standard, the workingcondition when the amount of natural gas for pressure regulating and liquefying are separately10000Nm~3/h, is simulated by using Aspen-plus software. The results show that183kW electricpower is produced,219kW cold energy is saved in this condition and the energy efficiency isgood. By analyzing the exergy efficiency of the optimization process system, the exergyefficiency of expansion machine is found as76.10%,the heat exchanger42.20%, and thewhole optimization system72.58%, so the heat exchanger can be seen as the optimizationdirection to improve system efficiency.Combining with the background of Qiuyu Ling safe storage and pressure regulatingstation in Shenzhen city, engineering design for the optimization process is done. The amountof LNG reserve storage is determined as40000m~3, the amount of natural gas for gasificationand liquefaction are determined as200000Nm~3/h and300000Nm~3/d, to meet the gas supplydemand in Shenzhen city. Through Aspen-plus simulation software, it concludes that therequired natural gas flow in pressure regulating process is4800kg/h, producing electric power 112kW and cooling power133kW. The selection of key equipment is completed according tothe technological parameters. The technological economics of the project is analyzed, and itcan be found that the project investments3.45million yuan, annual benefits0.26million yuan,payback period7.49years. Analyzing operating flexibility of the technic, it shows that theoptimization process has a good flexibility, the system is safe and reliable with good energysaving and economic benefits, and it is worthy of promotion.