Simulation and scheme comparison of CNG transmission and uploading pipe network system in stranded gas fields

Natural gas, as a clean energy source, is gaining popularity in terms of production and consumption. Nevertheless, due to limited gas production, scattered distribution, and challenging topographical conditions in several gas fields, the typical costs associated with pipeline transportation are elevated and impossible to use effectively, leading to "stranded gas fields". To investigate the technological feasibility of uploading CNG to the transmission network, this study compares two uploading schemes: throttling compression upload system(TCUS) and direct compression upload system(DCUS). The simulation model of the CNG transmission and uploading network process was created using Matlab/Simulink software to investigate the effects of the switching pressure differential and regulating pressure on system parameters in the TCUS. Additionally, a comparison between TCUS and DCUS was conducted to analyze the differences in volume flow, unloading rate, energy consumption, and other relevant aspects. The results show that the unloading rate of the CNG uploading system with a compressor is nearly 30 % higher than that of the free unloading system. In the TCUS, the lower the regulating pressure, the faster the pressure drop of the tank, the higher the gas uploading rate, and the higher the total electrical power consumption of the system. The larger the switching pressure differential, the earlier the compressor intervenes, resulting in a faster gas uploading rate, however, this also increases the system's total energy consumption. The difference in gas uploading rates between the TCUS and DCUS is minimal, but the DCUS offers greater advantages in energy consumption.