Reactive distillation (RD) combines reaction and separation in an integrated setup that is able to reduce the energy use, improve productivity and selectivity, and increase the efficiency. In previous work, we showed the design, modeling and experimental validation of a RD process for synthesis of unsaturated polyesters. The results of our previous work clearly demonstrated that reactive distillation is indeed a very promising alternative for the polyesters synthesis. This study explores the best suitable internals and various feed configurations of a reactive distillation process for unsaturated polyester synthesis. Multi-product simulations were performed to find the operational parameters for producing different grades of polyester in the same equipment. The product transition time during product changeover is determined for various configurations and product grades. The selection criteria for the best configuration are the minimum requirements of volume and energy to produce 100 ktpy polyesters. The results of the rigorous simulations carried out in Aspen Custom Modeler shows that the best configuration has the reactive stripping section as a packed or trayed bubble column, and the reactive rectifying section as a packed column. With respect to the feed configuration, the feeding of monoesters to the RD column significantly intensifies the polyester process as compared to an anhydrous reactant fed to the column. Moreover, the product transition time in this configuration is also significantly reduced as compared to the other configurations. (C) 2013 Elsevier Ltd. All rights reserved.