Prediction of Physical Properties and Phase Characteristics of Ethane and Ethane Mixture in the Ethane Pipeline

Abstract

In order to realize the safe transportation of liquefied ethane pipeline in the Oilfield of China, it is necessary to fully study the process of pipeline replacement, operation and shutdown. The accurate calculation of physical property parameters and critical parameters is the basis of studying the gas-liquid two-phase flow and heat and mass transfer process of liquefied ethane in the pipeline. In this paper, different equations of states (EOSs) were used to predict the physical properties (such as density, dew point and dynamic viscosity) of ethane or ethane mixture, and the predicted results were compared with the corresponding experimental data from the literature. The prediction performance of different EOSs were evaluated by using two evaluation indicators, including average absolute deviation (AAD) and average relative deviation (ARD). The results showed that the PR-Peneloux EOS has the best performance for predicting the density of CH4-C2H6-N2 mixture with an ARD value of 4.46%; for predicting the dew point, the BWRS EOS exhibits the superior performance with an ARD value of 0.58%; and for predicting dynamic viscosity, the SuperTRAPP formula has the smallest calculation error, with an ARD value of 1.33%. Considering the comparison results of the calculation accuracy of density, dew point and dynamic viscosity of ethane or ethane mixture by using different EOSs, PR-Peneloux EOS was recommended to calculate the phase characteristics in the process of ethane pipeline replacement operation. The phase characteristics of ethane for pipeline transport in the oilfield of China were obtained. The critical temperature is 32.79℃ and the critical pressure is 4.97 MPa.