Evaporation of 1kg of water from a solution in a single effect evaporator requires about ________________ kg of steam?

Related Mcqs:

1. It is desired to concentrate a 20% salt solution (20 kg of salt in 100 kg of solution) to a 30% salt solution in an evaporator. Consider a feed of 300 kg/min at 30°C. The boiling point of the solution is 110°C, the latent heat of vaporisation is 2100 kJ/kg and the specific heat of the solution is 4 kJ/kg.K. The rate at which the heat has to be supplied in (kJ/min) to the evaporator is____________________?

   A. 3.06 × 105
   B. 6.12 × 105
   C. 7.24 × 105
   D. 9.08 × 105

2. A dilute aqueous solution is to be concentrated in an evaporator system. High pressure steam is available. Multiple effect evaporator system is employed, because__________________?

   A. Total heat transfer area of all the effects is -less than that in a single effect evaporator system
   B. Total amount of vapor produced per Kg of feed steam in a multiple effect system is much
   higher than in a single effect
   C. Boiling point elevation in a single effect system is much higher than that in any effect in a
   multi-effect system
   D. Heat transfer co-efficient in a single effect is much lower than that in any effect in a multieffect
   system

3. In a single evaporator system, the steam economy ________________ by creating vacuum in the evaporator?

   A. Increases
   B. Decreases
   C. Remain constant
   D. May increase or decrease, depends on the vacuum

4. A multiple effect evaporator as compared to a single effect evaporator of the same capacity has _________________?

   A. Lower heat transfer area
   B. Lower steam economy
   C. Higher steam economy
   D. Higher solute concentration in the product

5. For the same heat transfer area and the terminal conditions, the ratio of the capacities of a single effect evaporator to a triple effect evaporator is_________________?

   A. 3
   B. 0.33
   C. 1
   D. 1.33

6. For evaporation of viscous solution in a multiple effect evaporator, the preferred feeding scheme is _________________?

   A. Forward
   B. Backward
   C. Parallel
   D. None of these

7. What is the steam economy in case of a single effect evaporator system ?

   A. 1
   B. > 1
   C. < 1
   D. 0.1

8. Steam consumption in kg/hr in case of an evaporator is given by (where, C & E are capacity the economy of the evaporator respectively) ?

   A. C/E
   B. E/C
   C. CE
   D. 1/CE

9. For concentrating an aqueous solution of a material like anhydrous Na2SO4, whose solubility decreases with rise in temperature, the most suitable evaporator is a _______________ evaporator?

   A. High pressure
   B. Vacuum
   C. Backward feed
   D. None of these

10. Steam economy in case of a triple effect evaporator will be _________________?

    A. 1
    B. < 1
    C. > 1
    D. Between 0 and 1