An integrated process system model has been developed for coupled separation operations involving two independent solvent circulation loops. This flow scheme is characterized by lower strippant (energy) consumption compared to the single loop configuration. The character of the relation between the strippant and solvent throughputs satisfying a given purification ratio has been analysed. Interesting characteristics of this flow structure concerning the effect of design and operating parameters such as the total number of stages, the ratio of the separation capacities, and the solvent circulation rates in the two loops on the system behaviour are uncovered. A systematic approach to the design optimization of single and twin loop flow structures is presented.