Page 333 - Chemical engineering design

308
CHEMICAL ENGINEERING
7.3. Choose a suitable material of construction for the following duties:
Ž
1. 98 per cent w/w sulphuric acid at 70 C.
Ž
2. 5 per cent w/w sulphuric acid at 30 C.
Ž
3. 30 per cent w/w hydrochloric acid at 50 C.
Ž
4. 5 per cent aqueous sodium hydroxide solution at 30 C.
Ž
5. Concentrated aqueous sodium hydroxide solution at 50 C.
Ž
6. 5 per cent w/w nitric acid at 30 C.
7. Boiling concentrated nitric acid.
8. 10 per cent w/w sodium chloride solution.
9. A 5 per cent w/w solution of cuprous chloride in hydrochloric acid.
10. 10 per cent w/w hydrofluoric acid.
In each case, select the material for a 50 mm pipe operating at approximately 2
bar pressure.
7.4. Suggest suitable materials of construction for the following applications:
3
1. A 10,000 m storage tank for toluene.
3
2. A 5.0m tank for storing a 30% w/w aqueous solution of sodium chloride.
3. A 2m diameter, 20 m high distillation column, distilling acrylonitrile.
3
4. A 100 m storage tank for strong nitric acid.
3
5. A 500 m aqueous waste hold-up tank. The wastewater pH can vary from 1 to
12. The wastewater will also contain traces of organic material.
6. A packed absorption column 0.5 m diameter, 3 m high, absorbing gaseous
hydrochloric acid into water. The column will operate at essentially atmospheric
pressure.
7.5. Aniline is manufactured by the hydrogenation of nitrobenzene in a fluidised bed
Ž
reactor. The reactor operates at 250 C and 20 bar. The reactor vessel is approxi-
mately 3 m diameter and 9 m high. Suggest suitable materials of construction for
this reactor.
7.6. Methyl ethyl ketone (MEK) is manufactured by the dehydrogenation of 2-butanol
using a shell and tube type reactor. Flue gases are used for heating and pass though
the tubes. The flue gases will contain traces of sulphur dioxide. The reaction
products include hydrogen.
The reaction takes place in the shell at a pressure of 3 bar and temperature of
Ž
500 C. Select suitable materials for the tubes and shell.
7.7. In the manufacture of aniline by the hydrogenation of nitrobenzene, the off-gases
from the reactor are cooled and the products and unreacted nitrobenzene condensed
in a shell and tube exchanger. A typical composition of the condensate is, kmol/h:
aniline 950, cyclo-hexylamine 10, water 1920, nitrobenzene 40. The gases enter
Ž
Ž
the condenser at 230 C and leave at 50 C. The cooling water enters the tubes at
Ž
Ž
20 C and leaves at 50 C. Suggest suitable materials of construction for the shell
and the tubes.
7.8. A slurry of acrylic polymer particles in water is held in storage tanks prior to
filtering and drying. Plain carbon steel would be a suitable material for the tanks,
but it is essential that the polymer does not become contaminated with iron in
storage. Suggest some alternative materials of construction for the tanks.