In recent years, due to the limited energy resources and increasing consumption and high cost of providing it, various methods for reducing energy consumption are presented. However, the use of energy wasted in the process has become a very important object. Almost in all chemical processes, separation section is very important section. Distillition is the most common industrial separation method and uses a lot of energy.In general, for a partial separation of a mixture to its pure components, different arrangements of distillation towers can be used. Therefore, for designing a distillation process, finding the best arrangement of distillation towers is very important. Cost minimizing and investigating of energy consumption in the triple system of propane, butane and pentane is aim of this project. The objective function is the Total Annual Cost of distillation arrangements. Four different arrangements are considered to find the optimum mod. All arrangements are both with and without thermal integration. Finding the extermum of objective function considering the number of variables is not an easy process. Short cut methods have been used in the past to ease investigation but suffer from simplifying assumption. In this project, genetic algorithm is used to find extermum of objective function. Distillation towers heve been simulated and sized by Hysys, total annual cost has been calculated. Finally, to ensure the accuracy of cost calculations, some of best cases were analysed by "Aspen Icarus" software and exact economic estimations have been performed. The results show that the splitting feed and partely heated integrated prefractionator arrangement is optimum arrangement compared with other arrangements. Keywords: Cost minimizing, Energy consuption, Total Annual Cost, genetic algorithms, Hysys software, Aspen Icarus software
