چكيده به لاتين
With the increasing need of industries for energy sources and the destructive effects of fossil fuel consumption on the environment, such as global warming, much research has been conducted in the field of energy saving in oil and gas processes. The distillation process can account for a significant portion of operating costs, particularly the annual costs of the processing unit. Due to the high energy consumption in this process, exergy loss and greenhouse gas emissions occur in large quantities. Among the distillation processes, the NGL process is very important due to the production of basic products of the value chain of petrochemical industries in high capacity. To choose the optimal sequence of the distillation column according to the research, one of the common problems is how to analyze and decide the results of different objective functions. Therefore, it is necessary to develop a multi-objective algorithm to design a zeotropic multi-component distillation setup with high computational speed to reduce the economic costs of the process, exergy loss, and greenhouse gas emissions separately. In this research, first, by using the separation matrix method, all kinds of sequences are produced, and after the translation of the separation matrices, simulation, and optimization operations are performed for each sequence. The proposed algorithm performs shortcut and precise optimization in two stages, and in the first stage, undesirable sequences are removed according to the results of the Pareto front. Also, the approaches of the shortcut simulation stage are presented to improve the identification of superior sequences and reduce the search space by the proposed algorithm. On the other hand, there are many types of multi-objective optimization algorithms, and an algorithm that has high accuracy and speed in identifying the Pareto front should be selected. In this regard, nine common multi-objective algorithms were investigated in two stages, and the NSGA-II algorithm was selected as the appropriate method for the analysis of 17 simple and complex arrangements of the distillation column. In order to reduce the total computing time in the first stage, two shortcut simulation approaches were proposed to reduce the search space, which can reduce the total computing time by 53%. The optimization results indicate that using the complex arrangement of SM7 compared to the simple arrangement of the studied industrial unit, due to improved operating conditions and isolation, will save 17% of TAC and reduce greenhouse gas emissions by 31%.
