Use a process simulator to find the optimum feed stage and total number of equilibrium stages for Problem 3.D6. Report the VLE correlation used. Record the values of \(Q_{\text {condenser }}\) and \(Q_{\text {reboiler }}\) (in Btu/h).

Transcribed Image Text:

D6.* A distillation column receives a feed that is 40 mol% n-pentane and 60 mol% n-hexane. Feed flow rate is 2500 lbmol/h, and feed temperature is 30C. The column is at 1 atm. A distillate that is 99.9 mol% n-pentane is desired. A total condenser is used. Reflux is a saturated liquid. The external reflux ratio is Lo/D = 3. Bottoms from the partial reboiler is 99.8 mol% n-hexane. Find D, B, QR, and Qc. Note: Watch your units on temperature. Data: Ac5 11,369 Btu/lbmol = 13,572 Btu/lbmol, both A at boiling points. = 39.7 (assume constant) 51.7 (assume constant) CPL,C5 CPL,C6 CPV,C5 CPV,C6 = 27.45 + 0.08148 T - 4.538 x 10-5 T2 + 10.1 x 10-9 T = 32.85 + 0.09763 T-5.716 x 10-5 T2 + 13.78 10-9 +3 where T is in C and Cpy and CPL are cal/(molC) or Btu/(lbmolF). Assume the heat of mixing is zero. Additional data are in Table 2-7. Source for A and Cp data is Felder et al. (2018). TABLE 2-7. Data for light alkanes Component MW , kJ/kg, at Cpy, kJ/(kg C), TC CPL kJ/(kg C), TC 25C Ethane 30.07 489 1.754+0.00418(T- 2.42+0.0087(T-25) 25) n-Butane 58.12 386 1.68 0.00432(T25) 2.344 + 0.003(T - 25) n-Pentane 72.15 358 n-Hexane 86.18 337 1.71 0.00419(T25) 2.29 +0.0033(T - 25) 1.71 0.00415(T25) 2.227 + 0.0041(T - 25) n-Heptane 100.21 320 n-Octane 114.23 301 1.85 0.00185(T25) 2.21 +0.00326(T- 25) 2.437 +0.0035(T25) 2.20 + 0.00425(T- 25)