A high vapour velocity is required for high plate efficiency in a sieve plate column. The satisfactory value of operating vapor velocity for design purpose in sieve plate column is about _______________ percent of the flooding velocity?

Related Mcqs:

1. Pick out the wrong statement about the design of sieve plate column and the bubble cap column ?

   A. The downcomer design and the residence time in the downcomer is almost same for sieve
   plate and bubble cap columns
   B. Weir length for a bubble cap plate is the same as that for the sieve plate
   C. Weir height for a bubble cap plate column is the same as that for a sieve plate column
   D. Weir height in case of a bubble cap plate ranges from 50 to 150 mm and is higher than the
   sieve plate

2. Vapor velocity in a distillation column for non-foaming mixture is in the range of ______________ times the flooding velocity?

   A. 0.1 to 0.3
   B. 0.6 to 0.7
   C. 0.85 to 0.95
   D. 1.5 to 2

3. The operating velocity in the absorption tower is usually 40-50% of the flooding velocity. Packed absorption towers are normally designed for a pressure drop of about _________________ mm of water column per metre height of packing?

   A. 1-5
   B. 20-40
   C. 100-150
   D. 1000-1500

4. Pick out the wrong statement about the design of a sieve plate column ?

   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

5. In sieve plate column, holes are drilled or punched in sizes ranging from 2.5 to 12 mm (5 mm being widely used). The hole pitch is normally ______________ times the hole diameter to give the required hole area?

   A. 0.5 to 1.5
   B. 2.5 to 4.0
   C. 5 to 10
   D. 10 to 15

6. Overall distillation column efficiency for most of the refinery columns can be given by (for μ = 0.07 – 1.4 cp and relative volatility < 4) (where ε = overall column efficiency, % μ = molal average viscosity of feed at average column temperature and pressure, cp Δp = pressure drop per tray, psi) ?

   A. η = 17 – 61.1 log μ
   B. η = 24.6 (Δp/μ)
   C. η = 1.66 – 0.25 log μ
   D. η = 0.25 log μ – 1.67

7. The design stress, which is more than the damaging stress, is the least unit stress that will render a member unfit for service before the end of its normal life. The design stress factor or factor of safety indicates the margin between design stress and the _______________ stress?

   A. Working
   B. Damaging
   C. Allowable
   D. None of these

8. In packed absorption tower, onset of flooding usually occurs at a pressure drop of about ______________ mm of water column per metre height of packing?

   A. 25-50
   B. 50-75
   C. 200-250
   D. 750-1000

9. Hole diameter of the sieve trays in the distillation column ranges from ______________ mm?

   A. 1 to3
   B. 4 to 8
   C. 3 to 12.5
   D. 12.5 to 18.5

10. Diameter of the sieve tray column is determined by the_________________?

    A. Lower limit of vapour velocity
    B. Upper limit of the vapour velocity
    C. Hole diameter of the sieve tray
    D. Height of the plate spacing