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Unformatted text preview: iler with minimum reflux. (f) Feed to the reboiler with total reflux. Analysis: Either a graphical or analytical method can be used. Because the relative volatility is assumed constant, use an analytical method. For each part, the theoretical plate and the partial reboiler are equilibrium stages. Benzene is the more volatile component, so the y-x diagram is based on benzene. Because the relative volatility = constant = 2.5, the equilibrium relationship is given by Eq. (7-3), x 2.5x y= = (1) 1 + x ( - 1) 1 + 15x . Take as a basis, 100 moles of feed. Therefore, the feed is 50 moles of A and 50 moles of B.
(a) With no reflux, separation occurs only in the reboiler. The vapor leaving the reboiler is totally condensed to become the distillate with yD = xD = 0.75. Solve Eq. (1) for equilibrium x, 0.750 yD = = 0.545 (2) y D + (1 - y D ) 0.750 + 2.5(1 - 0.750) Because the distillate and bottoms have benzene mole fractions greater than the mole fraction of the feed (0.5), it is impossible to obtain a distillate with a benzene mole fraction of 0.75. xB = (b) From...
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