Low pressure steam (with saturation temperature between 105 to 120°C) is usually used in the vacuum evaporators, which normally employ a vacuum of about _______________ mm Hg (referred to a 760 mm mercury barometer)?

Related Mcqs:

1. In which of the following evaporators, steam is fed inside the tube while the liquor is outside the tube ?

   A. Long tube vertical evaporator
   B. Short tube vertical evaporator
   C. Horizontal tube evaporator
   D. None of these

2. Pressure differential maintained across a continuous rotary vacuum filter is in the range of _______________ mm Hg column?

   A. 50 to 100
   B. 100 to 150
   C. 250 to 500
   D. 600 to 700

3. 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

4. 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

5. Large process vessels operating under extreme temperature and pressure conditions are normally clad/ lined with materials like stainless steel, aluminium, nickel & its alloys, copper & its alloys and titanium. The cladding thickness is generally about ______________ percent of the total thickness?

   A. 1 to 5
   B. 10 to 20
   C. 30 to 40
   D. 40 to 50

6. Steam economy is defined as the amount of evaporation per unit amount of steam used, while the capacity is the total evaporation obtained per hour. Use of multiple effects in evaporation ?

   A. Increases capacity
   B. Increases economy
   C. Does not affect the capacity
   D. Both B. & C.

7. Diameter of bubble caps used in high pressure columns is ______________ as compared to that used in identical vacuum columns?

   A. Less
   B. More
   C. Same
   D. Either A. or B.; no generalisation can be made

8. Number of evaporators which can be used in service in a multiple effect evaporation system is limited by the__________________?

   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.

9. The testing pressure of storage tanks and pressure vessels designed as per Indian standard codes should be about ______________ times the design pressure?

   A. 1.5 to 2
   B. 3 to 4
   C. 4 to 5
   D. > 5

10. 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