Page 179 - Analysis, Synthesis and Design of Chemical Processes, Third Edition

electricity costs $0.06/kWh.)

One way to produce very pure oxygen and nitrogen is to separate air using a distillation process. For
such a separation determine the following.
a. Find the normal boiling point (at 1 atm pressure) of nitrogen and oxygen.
b. For a distillation column operating at 1 atm pressure, what would be the top and bottom
temperatures and top and bottom compositions of a distillation column that separates air
11.
into nitrogen and oxygen? (For this problem, you may assume that air contains only nitrogen
and oxygen and that pure components leave at the top and bottom of the column.)

c. At what pressure can oxygen and nitrogen be liquefied at ambient temperature (say 40°C)?
d. What does the answer to part (c) tell you about the potential to distill air at ambient
conditions?

The production of ammonia (a key ingredient for fertilizer) using the Haber process takes place at
temperatures of around 500°C and pressures of 250 atm using a porous iron catalyst according the
following highly exothermic synthesis reaction:
12.
N (g) + 3H (g) ⇋ 2NH (g)
2 2 3 ΔH = –92.4 kJ/mol

Give possible reasons for the high temperature and pressure used for this reaction.

Consider the ammonia process in Problem 12. For the given conditions, the maximum single-pass
13. conversion obtained in the reactor is about 15–20%. Explain how the temperature and pressure
should be adjusted to increase this conversion and the penalties for making these changes.

For the production of drying oil shown as Project B.4 in Appendix B, do the following.
a. Construct a process conditions matrix (PCM) for the process, and determine all conditions
of special concern.
14. b. For each condition of special concern identified in part (a), suggest at least one reason why
such a condition was used.
c. For each condition of special concern identified in part (a), suggest at least one process
alternative to eliminate the condition.

For the styrene production process given in Project B.3 in Appendix B, do the following.
a. Construct a process conditions matrix (PCM) for the process, and determine all conditions
15. of special concern.
b. Explain the reasons for using the conditions of special concern in the reactor.
c. Suggest any process alternatives for part (b).