Effect of reflux ratio and number of stages on purity of ethylene in ethane-ethylene distillation using HYSYS process modeling software is presented in this paper. Results showed that purity of separation is directly proportional to reflux ratio as well as number of stages. A mixture of ethane and ethylene is pre flashed in a shortcut distillation column and parameters such as external reflux ratio, minimum reflux ratio, minimum number of stages, actual number of stages, optimal feed stage, condenser temperature, reboiler temperature and also condenser and reboiler duties are obtained. Then this feed is employed in a full scale distillation column to obtain the final results. Simulation shows that it is possible to achieve a purity as high as 99.2% using less than 100 plates, 84 plates to be precise. Optimum reflux ratio was also obtained. Results demonstrated that extra cost of using membrane systems to improve separation efficiencies can be avoided by using optimum reflux ratio in ordinary distillation.
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