A distillation column is fed 500 kmol/h of an equimolar mixture of pentane and hexane. The feed is saturated liquid.

It is necessary to produce outlet streams containing 95 mol%

pentane and 99 mol% hexane. The distillation column contains a partial reboiler and a total condenser.

1. Determine the exit flowrates D and B.

2. If the reflux ratio is one, determine all of the internal molar flowrates in the column.

3. Estimate the condenser and reboiler heat loads.

4. In the summer, cooling water is available at 30°C and is returned at 40°C.

In the winter, cooling water is available at 25°C and is returned at 35°C.

Assuming a 10°C approach in the condenser, based on the cooling water return temperature, determine the seasonal top column pressures.

5. If the column pressure drop is 15 kPa, determine the seasonal bottom column temperatures.

6. There are 15 equilibrium stages, with the feed on stage 5. Determine the diameter of a sieve tray column with 24-in tray spacing for 70% of flooding and an active tray area of 88%. Calculate the diameter for both the top and bottom sections. If the column is designed for the larger diameter, how will the other section perform?

7. Determine the diameter of a packed column with 2-in, ceramic Berl saddles at 70% of flooding. Calculate the diameter for both the top and bottom sections. If the column is designed for the larger diameter, how will the other section perform?

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Data: Hfeed = 0.25cP, PL = 650kg/m³ A5 = 25, 720kJ/kmol,A6 = 29, 632kJ/kmol SG5,L = 0.626 SG6,L = 0.655 H5,L= 0.173cP, M5,L = 0.175 CP log10 P (mm Hg) = 6.85296 - log10 p* (mm Hg) = 6.87601 - 1064.84 T(°C)+232.012 1171.17 T(°C)+224.408