Consider the hypothetical perfect separation of a mixture of ethylene and ethane into pure products by distillation as shown in Figure 10.39.

Two schemes are to be considered: conventional distillation and distillation using a heat pump with reboiler liquid flashing. In both cases, the column will operate at a pressure of \(200 \mathrm{psia}\), at which the average relative volatility is 1.55 . A reflux ratio of 1.10 times minimum, as computed from the Underwood equation, is to be used. Other conditions

for the scheme using reboiler liquid flashing follow. Calculate the following for each scheme:

(a) Change in availability function \(\left(T_{0}=100^{\circ} \mathrm{F}\right)\)

(b) Lost work

(c) Thermodynamic efficiency Other thermodynamic data are:

Figure 10.39:-

Transcribed Image Text:

Feed 2 Vapor Liquid Flow Rate, Ibmol/hr Stream 1 Stream 2 Stream 3 H 0.98 0.95 0.03 N 0.22 0.21 0.01 Benzene 0.08 0.00 0.08 Cyclohexane 91.92 0.69 91.23 Stream 1 Stream 2 Stream 3 Temperature, F 120 119.9 Pressure, psia 300 15 119.9 15 Enthalpy, 1,000 Btu/hr -3,642.05 -14.27 -3,627.78 Entropy, 1,000 Btu/hr-"R 4.920 0.094 4.860 Figure 10.34 Adiabatic flash separator.