a. Aspen Plus automatically generates residue curves for ternary mixtures. Generate residue curve at \(5.0 \mathrm{~atm}\) for a mixture of propane, \(n\)-butane, and n-pentane. Report the VLE correlation used.
b. To obtain an idea of what this means, simulate a column with a total condenser and kettle-type reboiler at \(5.0 \mathrm{~atm}\) with 50 stages, a saturated liquid feed on stage 25 with \(\mathrm{F}=100.0 \mathrm{kmol} / \mathrm{h}\), mole fractions of all three components \(=0.333333\), and initially far from total reflux \((\mathrm{L} / \mathrm{D}=0.999)\). Set \(\mathrm{D}=66.6667\) to put pentane in bottoms. Generate a plot of liquid compositions versus stage location. To generate the plot, after the run, click the blue box with a checkmark. Then use the button with \(<<\) to go to compositions. In the toolbar, you will now see a button labeled Plot. Click this button and then click Plot Wizard in the menu. Click Next, click the plot type Comp, and click Next again. To plot all three components, click the >> button. To plot liquid compositions, click the liquid button in middle of page. Click Next again and then Finish. This gives the desired plot. Print it, and label the conditions ( \(\mathrm{L} / \mathrm{D}\), mole fraction of feed, \(\mathrm{D}\), and \(\mathrm{N}\) ) on the plot. Note that complete separation is obtained.
c. Simulate the same system as in part \(\mathrm{b}\) but with \(\mathrm{D}=33.3333\). For the following, "essentially complete separation" means the propane mole fraction in distillate \(>0.990\). Is it possible to obtain essentially complete separation with
c1. \(\mathrm{L} / \mathrm{D}=0.999, \mathrm{~N}=100\), and \(\mathrm{N}\) feed \(=50\) ?
c2. \(\mathrm{N}=50\) and \(\mathrm{N}\) feed \(=25\) with \(\mathrm{L} / \mathrm{D}=2.0\) ?
c3. \(\mathrm{N}=10\) and \(\mathrm{N}\) feed \(=5\) with \(\mathrm{L} / \mathrm{D}=2.0\) ?
c4. \(\mathrm{N}=10\) and \(\mathrm{N}\) feed \(=5\) with \(\mathrm{L} / \mathrm{D}=10.0\) ?
c5. \(\mathrm{N}=6\) and \(\mathrm{N}\) feed \(=3\) with \(\mathrm{L} / \mathrm{D}=50.0\) ?
Print plots for cases with complete separation, and label the conditions on the plots.
d. The residue curve obtained implies that you can obtain pure propane or pure \(\mathrm{n}\)-pentane for any feed composition by setting \(\mathrm{D}\) appropriately and using a large enough \(L / D\left(>(L / D)_{\min }\right)\) and a large enough \(\mathrm{N}\) \(\left(>\mathrm{N}_{\text {min }}\right)\). To convince yourself that this is true, try two different feed compositions, and show that essentially pure n-pentane can be obtained.