2.18. Second-law analysis of a distillation. Column C3 in Figure 1.10 separates stream 5 into streams 6 and 7, according to the material balance in Table 1.5. The separation is carried out at 700 kPa in a distillation column with 70 plates and a condenser duty of 27,300,000 kJ/h. Using the following data and an infinite surroundings temperature To, of 298.15 K, compute: (a) the duty of the reboiler in kJ/h; (b) the irreversible production of entropy in kJ/h-K, assuming condenser cooling water at 25°C and reboiler steam at 100°C; (c) the lost work in kJ/h; (d) the minimum work of separation in kJ/h; and (e) the second-law efficiency. Assume the shaft work of the reflux pump is negligible. Phase condition Pressure, kPa Temperature, K Enthalpy, kJ/mol Jamal Entropy, kJ/kmol-K Feed Distillate Bottoms (Stream 5) (Stream 6) (Stream 7) Liquid Liquid Liquid 348 323 343 1,950 700 730 17,000 13,420 15,840 25.05 5.87 21.22

ISBN: 9781259696527

Author: J.M. Smith Termodinamica en ingenieria quimica, Hendrick C Van Ness, Michael Abbott, Mark Swihart

Publisher: McGraw-Hill Education