Major energy reductions can be obtained by heat integration in distillation columns. Potentially, this can lead to reductions in operation costs overcoming increased investment costs.
The types of heat integration for stand-alone distillation columns are external and internal, corresponding to vapor recompression and diabatic operation, respectively. Configurations, containing either or both types of heat integration, typically require compression. These configurations have a significantly higher number of design degrees of freedom, leading to complicated design procedures that often require models for simulation, though graphical methods also have been described, for binary mixtures.
In this presentation, an iterative design algorithm for the conceptual design of internally or externally heat-integrated distillation configurations is presented. The algorithm provides means of selecting all central design variables such as the column pressures, the heat exchange area(s), and the thermal coupling of internally heat-integrated column stages.
The application of the design algorithm is illustrated for a number of separations of varying degree of difficulty, including the separation of methanol/water. The resulting design is compared against designs based on approaches suggested in literature. In addition, the proposed design algorithm is used for designing a separation of a multicomponent mixture. Simulations are carried out for outlining the techno-economic performance of all design.
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