Abstract:
Objective The accuracy of the calculation results of different equations of state at home and abroad was investigated.
Methods The software module of GERG-2008 equation of state was compiled by Python3.6 and compared with the calculation results of AGA8-92DC, PR, SRK, CPA, BWRS equations, etc. The accuracy of different equations for calculating the compression factors of high sulfur gas with different compositions was evaluated.
Results (1) The calculation accuracy of GERG-2008 equation and AGA8-92DC equation is basically the same for pipelined natural gas with simpler components specified in the standard, and the calculation accuracy of the two equations is less than 0.10% in the temperature and pressure range of natural gas pipeline. (2) Based on the calculation results for the compression factor experimental data of 331 groups of high sulfur gas, the GERG-2008 equation has the highest accuracy, with the deviation range of 0.31%-1.14% and the average deviation of 0.67%, which is 14.9% higher than that of AGA8-92DC. (3) For H2S content in the range of 0%-27%, the accuracy of compression factor calculation methods is in the order of GERG-2008, AGA8-92DC, CPA, BWRS, SRK and PR. Due to limited experimental data, focused on calculation and analysis under certain working conditions, calculation accuracy for most of the existing studies in a wider range needs to be further verified. (4) ISO 20765-2:2015 is an international standard for physical property calculation of natural gas of different compositions and phases formulated on the basis of the GERG-2008 equation.
Conclusions The GERG-2008 equation is very accurate for the calculation of compression factors in natural gas pipeline transmission and high sulfur gas reservoirs. It is suggested that relevant organizations of the natural gas industry accelerate the transformation process of the international standard and its follow-up standards.