Though a fully thermally coupled distillation column-an energy efficient distillation system-consumes less energy, it is not widely implemented in practice due to its operational difficulty. A 3-column distillation system having improved operability is proposed here, and its energy saving performance and application related issues are investigated from the implementation result to a practical hexane process. When an energy integration is employed, the proposed system requires 18% less energy than a conventional 2-column system, which is found from the HYSYS simulation. Though more control loops than the 2-column system are required, the proposed system has better controllability of product compositions and the pressure control of the system is easier.