Modified simple column configurations for quaternary distillations

Distillation is the most energy demanding, capital intensive and widely used separation method. For quaternary distillation, the conventional simple column configurations employ three columns to achieve four products with any specified purity. In this paper, the modified simple column configurations are studied which use two columns to accomplish four-component separations with any specified purity. The modified simple column configurations have the significant process intensification feature that they use less number of columns and heat exchangers. To study the performance of the modified simple column configurations different four-component mixtures with different feed compositions were analyzed. The performance was studied in terms of energy, capital cost saving and column sections function. It was demonstrated that for the composition cases considered the proposed configurations have similar or better energy performance than the traditional simple column sequences, however significant capital cost reductions are achieved in all the cases studied.

• Distillation plants are widely used in the industrial practice and consume huge amount of energy and intensive capital investments.
• Intensified distillation sequences with only two columns for the separation of four component mixtures are examined.
• The distillation columns are connected with a liquid or a vapor sidestream.
• The possibility of energy and capital cost reduction was evaluated by comparison with the corresponding best simple column configuration.
• It was found that not all the distillation sections included in the simple column sequences perform a separation task.