In this study, a cryogenic distillation column has been designed and simulated via a computer code based on the theta method of convergence. The required thermodynamic properties are determined from the enhanced predictive Peng-Robinson (E-PPR 78) equation of state which has a good accuracy in predicting the corresponding thermodynamic properties of natural gas components. The combined code of distillation column/equation of state has been verified with that of another study. In the present study, the results are achieved by the constant molar over-flow and inclusion of energy equations assumptions. In order to have more accuracy in the results, the energy equations were considered in the column calculations. For improvement of column operational conditions, a parametric study is carried out. The results show that by the proper selection of reflux ratio, column operating pressure, feed plate location and considering energy constraints, the molar concentration of methane is decreased from 66.14% in the initial state to 13.75% in the improved state. (C) 2019 Elsevier B.V. All rights reserved.