Research on the Energy-saving Efficiency of the Backward-feed Double-effect Distillation

The effects of the feed composition and the feed temperature on the energy-saving efficiency of the backward-feed two-effect distillation are researched in ethanol-water system by process simulation.The following results are obtained.As to the energy-saving efficiency,the backward-feed B flow is best,the backward-feed C flow is better and the third is the backward-feed A flow.When the feed contain nearly the equal moles of light and heavy component,the energy-saving efficiency reach the maximum value of 49.83% for the backward-feed B flow.And the backward-feed C flow and A flow are better used at the conditions of the feed containing more light component.For the three backward-feed flows,the energy-saving efficiency all decrease with the increase of the feed temperature.They are better used at the conditions of the feed temperature being lower than the bubble point temperature.