The solar powered distillation of an ethanol-water mixture

The purpose of this study was to determine the H.T.U. under different operating conditions for a packed column operating at less than atmospheric pressure and to evaluate the viability of using one form of solar energy to provide the heat input to the reboiler for such a system. The majority of the experimental effort was focused on determining the effect that the operating pressure and steady state reboiler and distillate concentrations had on the height of a transfer unit decreased for an increase in either the operating pressure or the initial feed concentration. The values of the (H.T.U.)oG obtained in this investigation varied from 0.71 feet to l.24 feet for a packed height of 5.5 feet in an 8-inch internal diameter tower using 0.25inch Intalox saddles at total reflux.

The unique nature of the heat source used in this investigation required that the column be operated at less than atmospheric pressure. Two of the difficulties that were encountered when performing a vacuum distillation were: ( (1) significant product withdrawal by the vaccum pump when small air leaks existed and (2) air pockets preventing the transfer of fluids due to the location and type of valves located throughout the system.