# Question: Five hundred kmol h of a liquid mixture of light alcohols

Five hundred kmol/h of a liquid mixture of light alcohols containing, by moles, 40% methanol (M), 35% ethanol (E), 15% isopropanol (IP), and 10% normal propanol (NP) is distilled in a sequence of two distillation columns. The distillate from the first column is 98% pure M with a 96% recovery of M. The distillate from the second column is 92% pure E with a 95% recovery of E from the process feed. Assume no propanols in the distillate from Column C1, no M in the bottoms from Column C2. and no normal propanol in the distillate from Column C2.

(a) By material balances. assuming negligible propanols in the distillate from the first column, compute the flow rates in kmol/h of each component in each feed, distillate, and bottoms. Draw a labeled block-flow diagram like Figure. Include the results of the material balances in a table like Table 1.5 and place the table below your block-flow diagram.

(b) Compute the mole-percent purity of the propanol mixture leaving as bottoms from the second column in the sequence.

(c) If the recovery of ethanol is fixed at 95%, what is the maximum purity that can be achieved for the ethanol in the distillate from the second column?

(d) If instead, the purity of the ethanol is fixed at 92%, what is the maximum recovery of ethanol (based on the process feed) that can beachieved?

(a) By material balances. assuming negligible propanols in the distillate from the first column, compute the flow rates in kmol/h of each component in each feed, distillate, and bottoms. Draw a labeled block-flow diagram like Figure. Include the results of the material balances in a table like Table 1.5 and place the table below your block-flow diagram.

(b) Compute the mole-percent purity of the propanol mixture leaving as bottoms from the second column in the sequence.

(c) If the recovery of ethanol is fixed at 95%, what is the maximum purity that can be achieved for the ethanol in the distillate from the second column?

(d) If instead, the purity of the ethanol is fixed at 92%, what is the maximum recovery of ethanol (based on the process feed) that can beachieved?

## Answer to relevant Questions

A mixture of ethanol and benzene is separated in a network of distillation and membrane separation steps. In one intermediate step, a near-azeotropic liquid mixture of 8,000 kg/h of 23 wt% ethanol in benzene is fed to a ...A stream containing 7,000 kmol/h of water and 3,000 parts per million (ppm) by weight of ammonia at 350 K and 1 bar is to be processed to remove 90% of the ammonia. What type of separation operation would you use? If it ...A hydrocarbon stream in a petroleum refinery is to be separated at 1,500 kPa into two products under the conditions shown below. Using the data given, compute the minimum work of separation, Wmin , in kJ/h for To = 298.15K.A binary ideal-gas mixture of A and B undergoes an isothermal, isobaric separation at To, the infinite surroundings temperature. Starting with Eq. (4), Table 2.1, derive an equation for the minimum work of separation, ...Use the R-K equation of state to estimate the partial fugacity coefficients of propane and benzene in the vapor mixture of Example 2.5.Post your question