A novel distillation scheme which makes use of secondary reflux and vaporization to enhance thermal efficiency is presented. Low operating temperatures, close boiling mixture, and tight product specifications appear to favor this scheme over the conventional distillation. Computer simulation indicates a potential utility reduction of 50 to 7594,. SCOPEDistillation is the single most important separation unit operation in the process industry. It is widely used to upgrade feedstocks, separate reaction intermediates, arid purify products in processes ranging from cryogenic separation of oxygen, nitrogen, and helium to the recovery of aromatics from coal tar. In a recent study carried out under the auspices of the Governor's Energy Advisory Council of Texas, the energy usage of some forty-five refineries (in thirty-nine companies) and 226 chemical plants (in 140 companies) was surveyed (Prengle et al., 1974), and distillation was an important energy consumer in almost all of them. In petroleum refineries which are the largest energy consumers on a per plant basis (1.9 X 1016 J/plant), crude and vacuum distillation alone accounts for 22.5 to 51% of the total energy consumption. Any enhancement of efficiency of this important unit operation could have an impact which will significantly benefit a wide cross section of process industries.In the conventional distillation column, heat is sup-

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