天然气城市门站调压过程的火用分析

长距离高压管输天然气送至终端用户前，需经城市门站调压，满足一定压力等级后方可进入城市燃气输配管网。传统的节流阀工艺存在着巨大的过程火用损，且需辅以电伴热才能维持正常运行。为了提高管网运行的经济性和能源的利用效率，对调压过程进行了能量分析，指出在完成相同调压任务的情况下，采用透平膨胀机流程较之节流阀流程，可显著减少过程火用损、提高系统火用效率，具有明显的技术优势；进而提出了天然气管网调压过程物理火用回收利用流程，将压力能（压力火用用于发电，将调压工艺冷能（温度火用）用于制冷循环，以实现按质用能、能尽其用。

Exergy analysis in the pressure reduction process at the city gas gate stations

While being sent by long distance high pressure pipeline to the city gas gate stations, the pressure of pipeline gas has to be reduced to some degree to be allowed to enter the city gas pipeline network. A traditional throttle technology will result in an enormous exergy loss and the failure free operation has to rely mostly on the electrically heat tracing. In order to improve the energy efficiency and the cost effectiveness of city pipeline running, we carried out a study of energy analysis during the process of pressure regulation. The results show that under the same working station adopting the turbo expander instead of throttle valves significantly reduces the exergy loss in the process and improves the exergy efficiency of the system, exhibiting outstanding technical advantage. Furthermore, a module which aiming at recovering and utilizing physical exergy involved in pressure reduction process of natural gas pipeline network is proposed. Pressure exergy is utilized for power generation and temperature exergy for refrigeration simultaneously to achieve the effect of that energy will be utilized efficiently in accordance with its quality.