Separation of ethylene from light gas mixture is one of the most energy intensive separations in petrochemical processes, which uses distillation columns up to 100 m tall and containing over 100 trays due to very small differences in the relative volatilities and very large reflux ratios and also due to the need for sub-ambient temperatures. In recognition of these costs, several attempts have been made in the past to develop processes with less energy and equipment costs. In distillation columns with condenser temperatures significantly below room temperature, such as in ethylene separation towers, it is essential to minimize the expensive energy requirements of the refrigeration cycle that produces the tower reflux. In this work, a solution has been found by expanding the gaseous distillate to decrease its temperature. Moreover, additional solutions applied to conventional ethylene fractionation columns have been implemented here in order to study this behavior. In this contribution, an outlet stream of an Oxidative Coupling of Methane (OCM) reactor, which has been previously stripped of its CO2 content, is also introduced in a demethanizer tower to remove almost all of its CH4 content before entering the ethylene fractionating column. Then, it is cooled exchanging its heat with the distillate stream of the ethylene tower, warming the distillate. The main goal is to reduce the condenser heat duty. This objective is achieved reducing a significant amount of heat required by the condenser, maintaining the mandatory product purity. Due to this improvement, it was also possible to reduce the reboiler heat in almost the same percentage amount that is achieved with the condenser. In addition, the reflux of ethylene column decreases. The sensitivity analysis and the corresponding simulations results will be discussed in order to show the efficiency of the presented approach. These results have also been used for the design of the pilot plant which is now being built at our department. (C) 2011 Elsevier Ltd. All rights reserved.