When water is the more volatile component, we do not need a condenser but can use direct cooling with boiling water. This situation was shown in Problem 3.D3. \(\mathrm{y}_{\mathrm{D}}=0.92, \mathrm{x}_{\mathrm{B}}=0.04, \mathrm{z}=0.4\) (all mole fractions water), feed is a saturated vapor, feed rate is \(1000 \mathrm{kmol} / \mathrm{h}, \mathrm{p}=1 \mathrm{~atm}, \mathrm{CMO}\) is valid, the entering cooling water (flow rate \(\mathrm{C} \mathrm{kmol} / \mathrm{h}\) ) is a saturated liquid and is pure water, and \(C / D=3 / 4\). Derive and plot the top operating line. Note that external balances (i.e., balances around the entire column) and equilibrium data are not required.

Problem 3.D3.

D3.* A distillation column separating ethanol from water is shown in the following figure. Pressure is 1 kg/cm2. Instead of having a condenser, a stream of pure, saturated liquid ethanol is added directly to the column to serve as the reflux. The feed to the column is 40 wt % ethanol at -20C. Distillate concentration is 80 wt % ethanol, and bottoms composition is 5 wt % ethanol. A total reboiler is used, and the boilup is a saturated vapor. The reflux stream is input at C = 1000 kg/h. Find the external boilup rate, v. Note: Set up the equations, solve in equation form for, including explicit equations for all required terms, read off all required enthalpies from the enthalpy composition diagram (Figure 2-4), and then calculate a numerical answer. CXC. D.YD F, z Qcol=0 N X N, L VYN+I QR B, XB