准确度更高的高含硫天然气压缩因子计算方法

目的考查国内外不同状态方程计算结果的准确性。 方法通过python3.6编写了GERG-2008状态方程的软件模块,与AGA8-92DC、PR、SRK、CPA、BWRS等状态方程的计算结果进行对比分析,评估了不同状态方程对不同组成高含硫天然气压缩因子计算的准确性。 结果①对标准中规定的组成较简单的管输天然气,GERG-2008方程与AGA8-92DC方程的计算准确度基本相当,在天然气管输温度、压力范围内,两个方程的计算准确度均在0.10%以内；②基于331组高含硫天然气压缩因子实验数据的计算结果,GERG-2008方程准确度最高,偏差范围为0.31%~1.14%,平均偏差为0.67%,相比于AGA8-92DC提升了14.9%；③H₂S摩尔分数在0%~27%范围内,对于研究的几种状态方程的压缩因子计算方法,其准确度排序依次为:GERG-2008、AGA8-92DC、CPA、BWRS、SRK、PR。由于实验数据有限,现有研究大多是针对某种工况下的计算分析,其在更广的范围内计算准确性需要进一步验证；④ISO 20765-2:2015 Natural gas—Calculation of thermodynamic properties—Part 2:Single-phase properties(gas,liquid,and dense fluid)for extended ranges of application是以GERG-2008方程为基础制订的适用于不同组成、不同相态天然气物性计算的国际标准。 结论GERG-2008方程对管输天然气压缩因子、高含硫气藏天然气压缩因子的计算都十分准确,建议天然气行业相关组织加快该国际标准及其后续标准的转化进程。 

More accurate compression factor calculation method for high sulfur gas

ObjectiveThe 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. ConclusionsThe 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.