Development of Complex Batch Distilllation System for Energy Conservation

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A new type of separation system called "complex batch distilllation column" is proposed, and the characteristics of this column are examined.From the view point of energy consumption, batch distilllation has been considered to be an ineffective separation method compared with continuous distilllation. However, the complex column proposed here can be regarded as a multiple-heat-integrated system in which a condenser of one column is heat-integrated with the reboiler of the next column. Therefore, the energy required for separating multiple components is markedly less than that of an ordinary batch distilllation system.The complex column is convenient for removing light and heavy impurities from the raw materials since the impurities could be withdrawn simultaneously from the top and the bottom. By analyzing the differences between ordinary and stripping batch distilllation columns, the conditions at which the complex column works effectively compared with ordinary batch distilllation co … More lumn are clarified.The optimal structure of the batch distilllation column is discussed from the viewpoint of energy conservation. In this research, in addition to ordinary and stripping batch distilllation columns, many types of complex columns are taken into account. At first, by analyzing the differences among ordinary, stripping, and total reflux batch distilllation columns separating binary components, two heuristic rules with regard to the separation performance of those columns are derived. It becomes clear that, by using these heuristic rules, the candidates of the optimal structure can be limited to a few structures.The energy consumption of the complex column is compared with that of an ordinary continuous distilllation system for various separation conditions. Through exhaustive simulation work, it is found that in many cases the energy consumption of the complex column is the same or smaller than that of optimal continuous distilllation systems when the total number of trays is the same for both systems. Less