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. (C) 2011 Elsevier Ltd. All rights reserved.