Discussion
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- Question
Pick out the wrong statement about the design of a sieve plate column.
Options- A. An increased weir height improves the tray efficiency at the cost of high plate pressure drop; optimum wear height being 40-90 mm for column pressure above atmospheric and 6-12 mm for vacuum columns.
- B. For segmental downcomers, the chord length is 60-80% of the column diameter. An initial value of downcomer area of 12% is taken in the design.
- C. Width of the calming section provided at the inlet and outlet sides of the plate is 75 mm for column diameter below 1.5 metres and 100 mm for larger diameter columns.
- D. Minimum recommended downcomer residence time for the disengagement of entrained vapour is the same for both foaming and non-foaming liquids, which is about 20 seconds.
- Correct Answer
- Minimum recommended downcomer residence time for the disengagement of entrained vapour is the same for both foaming and non-foaming liquids, which is about 20 seconds.
- 1. In a distillation column, the minimum residence time for liquid in the downspout is about __________ seconds.
Options- A. 1
- B. 8
- C. 80
- D. 180 Discuss
- 2. An adequate clearance between the tray and the shell wall of a distillation column is provided to
Options- A. drain the liquid from the tray when the unit is not in operation.
- B. allow for thermal expansion and facilitate installation.
- C. avoid back-trapping.
- D. none of these. Discuss
- 3. Generally, no corrosion allowance in wall thickness of a part is required, if the thickness is more than __________ mm.
Options- A. 10
- B. 20
- C. 30
- D. 5 Discuss
- 4. The slope of the feed line in distillation opeartion is given by (where, q = fraction of the feed stream that is liquid.)
Options- A. -q
- B. -q/(1-q)
- C. -q/(q-1)
- D. none of these Discuss
- 5. Number of evaporators which can be used in service in a multiple effect evaporation system is limited by the
Options- A. practical limit reached, due to low heat transfer rate because of inadequate temperature difference.
- B. economic limit reached, when the plant cost exceeds the saving of steam.
- C. both (a) & (b).
- D. neither (a) nor (b). Discuss
- 6. The circumferential (hoop) stress in a thin walled cylinderical vessel under internal pressure is
Options- A. pd/2t
- B. pd/4t
- C. pd/t
- D. pd/3t Discuss
- 7. In case of a continuous distillation column, increase in reflux ratio may result in the
Options- A. lower fixed charges for the column.
- B. greater cost for the reboiler heat supply.
- C. greater cost for the condenser coolant.
- D. all (a), (b) and (c). Discuss
- 8. Floating head heat exchangers are used for the
Options- A. heat transfer between corrosive fluids.
- B. cases where temperature difference between the shell and the tubes is more (>50°C).
- C. co-current heat transfer systems.
- D. counter-current heat transfer systems. Discuss
- 9. In a shell and tube heat exchanger, tube side __________ of the mass velocity.
Options- A. heat transfer co-efficient is proportional to 0.8th power
- B. pressure drop is proportional to the square
- C. both 'a' & 'b'
- D. neither 'a' nor 'b' Discuss
- 10. In packed towers provided with saddle packing, liquid redistributors are positioned at every __________ times column diameter or 6 metres whichever is less.
Options- A. 2-3
- B. 5-8
- C. 10-15
- D. 20-25 Discuss
Process Equipment and Plant Design problems
Search Results
Correct Answer: 8
Correct Answer: allow for thermal expansion and facilitate installation.
Correct Answer: 30
Correct Answer: -q/(1-q)
Correct Answer: both (a) & (b).
Correct Answer: pd/2t
Correct Answer: all (a), (b) and (c).
Correct Answer: cases where temperature difference between the shell and the tubes is more (>50°C).
Correct Answer: both 'a' & 'b'
Correct Answer: 5-8
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