Normally, the length to diameter ratio of rotary dryers varies from 4 to 10 and for its economic operation; the number of transfer units (NTU) for such dryers varies from ?

Related Mcqs:

1. Tube wall thickness depends on the corrosiveness of the fluids and their operating pressure & temperature and is specified by Birmingham wire gauge (B.W.G)-a number which varies from 8 to 18 with the numbers 14 and 16 being more commonly used. Outside diameter of tubes varies from about 15 to 50 mm; however a tube of less than _____________ mm outside diameter is generally not recommended for fouling fluids ?

   A. 16
   B. 19
   C. 28
   D. 38

2. Length to diameter ratio of most rotary driers is in the range of____________________?

   A. 1 to 2
   B. 4 to 10
   C. 10 to 20
   D. 20 to 30

3. In a shell and tube heat exchanger for a given heat transfer surface area, smaller diameter tubes are favoured as compared to larger diameter ones; because the smaller diameter tubes ______________?

   A. Are easier to clean
   B. Are less prone to fouling
   C. Can be fitted into a smaller shell diameter hence the cost of the heat exchanger would be less
   D. None of these

4. For annular flow of a fluid, the ratio of the equivalent diameter for pressure drop calculation to the equivalent diameter for heat transfer calculation is_________________?

   A. d1/(d1 + d2)
   B. d2/(d1 + d2)
   C. (d1 + d2)/d1
   D. (d1 + d2)/d2

5. The diameter of a propeller agitator used in agitation tank ranges from ____________ percent of the tank diameter and its peripheral speed is normally 300 to 500 metres/minute ?

   A. 5 to 10
   B. 15 to 30
   C. 40 to 50
   D. 55 to 75

6. Rotary driers are most economically designed for the number of heat transfer units (HTU) from _________________?

   A. 0.01 to 1
   B. 1.5 to 2.5
   C. 5 to 10
   D. 10 to 20

7. Multiple blade paddle agitator is used for mixing high viscosity liquids/paste in which the paddle diameter is commonly 0.8 times the tank diameter. However, the width of the blade is in the range of ______________ times the paddle diameter?

   A. 0.1 to 0.25
   B. 0.3 to 0.5
   C. 0.5 to 0.6
   D. 0.65 to 0.80

8. Normally, the ratio of the total riser area to the tower cross sectional area (for bubble cap towers of diameter more than 3 ft) is around_______________?

   A. 0.4-0.6
   B. 0.35-0.75
   C. 0.1-0.2
   D. 0.55-0.85

9. Speed of the drum of the rotary vacuum filter normally ranges from _____________ rpm?

   A. 0.1 to 2
   B. 5 to 7
   C. 3 to 8
   D. 8 to 15

10. The difficulty of liquid distribution in packed towers is accentuated, when the ratio of tower diameter to packing diameter is_________________?

    A. < 30
    B. < 7
    C. > 7 20 < 50