The calculation technique of natural gas density in pipelines of large length

Abstract

The article refers to the question of natural gas density calculation, applying different equations of real gas
state while transporting it at pressures up to 25 MPa. Calculations of this parameter were carried out according to
the algorithms of American Gas Association (AGA 8), Benedict-Webb-Rubin, Soave-Redlich-Kwong and PengRobinson.
A comparative analysis of the accuracy of measurements of required parameters, obtained by these equations,
was performed as well. As a reference equation, it is proposed to use AGA 8 equation of state because of its
least uncertainty in comparison with the experimental values. However, it should be noted, that the Peng-Robinson
equation also accurately describes the specified range of operating pressures, though, it has uncertainty limits
1.6 ÷ 3.5% in comparison with AGA 8 method, unlike the other two. Therefore, Peng-Robinson equation can be
applied in practice in the specified range of operating pressures. The article additionally indicates the advantages
and disadvantages of the above mentioned algorithms in the course of their practical application. Furthermore, it is
emphasized on the importance of taking into account the physical properties of all components while calculating the
parameters of transportation of natural gas under ultrahigh pressures. For practical application it is offered to use
diagrams of the natural gas density at different pressures and temperatures.