Integrated Technology Research On Pressure Energy Utilization Of Nature Gas Pipe Network

Natural gas in our country mostly is conveyed to every gate station by high pressure,then is regulated to low pressure and enters the downstream gas pipeline network. Thereexists rich pressure energy during regulation, if this part energy can be effectively recovered,good economic benefits and social benefits will be produced. At present, scholars at home andabroad have studied the sigle recovery technology more, but the technology exists theweakness of inadequate energy utilization, low efficiency, so it is necessary to further studythe technology, in order to realize the highly utilization of pressure energy.This paper firstly studied five sigle pressure energy utilization technologies: pressreenergy using for electricity, CNG, refrigerator, natural gas liquefaction and cryogenicgrinding of waste rubber. And use software ASPEN PLUS to simulate these processes andanalize exergy efficiency and weak link of process with exergy analysis and energy utilizationdiagram (EUD) analysis method. The results show that single utilization technology exsitsphenomenon of cryogenic energy for high use and the exergy efficiency of whole process islow, between20%~40%. Meanwhile, different temperature zone was determined whichprovide the basis for the integrated design of the process: power for shallow cold temperaturezone, CNG and refrigerator for sencondary middle cold temperature zone, rubber grinding formiddle cold temperature zone and natural gas liquefaction for cryogenic temperature zone.The results provide theoretical basis for integrated process design.According to "temperature counterpart, cascade utilization and minimum exergy loss"principle and needs of different users, the paper respectively designed pressure using forpower generation-crushing-refrigerator integration technology and pressure using for power-CNG-refrigerator-air conditioning integration technology. The exergy analysis and and EUDanalysis results show that exergy efficiency of power generation-crushing-refrigeratorintegration technology and power-CNG-refrigerator-air conditioner integration technology isrespectively49.72%and56.67%, higher than single utilization technology; expander orcompressor is the weak link of the integration process, providing a direction for futureenergy efficiency optimization.Based on some pressure regulation station in the north and combined with peressureenergy integrated process, engineering design has been done and confirmed the integratedprocess of pressure energy using in power-CNG-refrigerator-air conditioning. And thefeasibility of the process has been confirmed through process design with control point, keyequipments selection, process elastic analysis and technology economy. The results show that with natural gas of50000Nm3/h, ranging from3.9MPa to0.4MPa, power produced is1452kW,6300kg/h CNG can be gotten, refrigerator load is387kW and the cold air conditioningload is325kW. The total investment of the proposed project is50.20million yuan, an averageannual revenue is10.84million yuan and payback period is only6.79years. The results ofengineering design provide a reference basis for the development integrated process ofpressure energy and implement of engineering design. And it is of great significance.