Forecasting the Compressibility Coefficient of Natural Gas in the Region of Negative Temperatures

Statement of the problem. Modern methods of measuring the flow rate of natural gas transmitted to the consumer require knowledge of the compressibility factor value at the measured pressure and temperature parameters. The existing regulatory literature does not contain data on the compressibility factor at temperatures below 250 K, while the climatic conditions of the northern territories of the Russian Federation have lower values, reaching 213.15 K. Results. The article presents the results of calculating the compressibility factor of natural gas in the temperature range from 273.15 to 213.15 K and pressures from 0.1 to 10 MPa using three equations of state of natural gas, taking into account the real properties used in modern regulatory literature. Averaged values for three methods were found. Conclusions. Approximate equations are proposed that allow calculating the compressibility coefficient of natural gas of standard composition in the temperature ranges of 213.15 K ≤ T ≤ 253.15 K and pressure of 0.1 ≤ p < 7 MPa and 7 < P ≤ 10 MPa with an average relative error in absolute value over the entire range of 0.08 and 0.333 %, respectively. The obtained results can be used for practical calculations of natural gas consumption.