A. Get economical temperature difference by using moderate pressure steam
B. Facilitate forward feeding in multiple effect evaporation
C. Concentrate heat sensitive materials
D. Achieve very high concentration of the final product
Related Mcqs:
- 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 - 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 - 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 - 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 - 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 - 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 - 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 - The purpose of providing bleed points in the evaporator is to__________________?
A. Admit the feed
B. Remove the product
C. Facilitate removal of non-condensable gases
D. Create vacuum - The purpose of providing a ‘catchall’ in the vapor line of an evaporator is to__________________?
A. Create vacuum
B. Regulate the vapor flow
C. Vent the non-condensable gases
D. Arrest the entrained liquid - The outlet temperature of cooling water in a heat exchanger is generally not allowed to exceed above 50°C in industrial practice mainly to avoid_________________?
A. Its evaporation loss
B. Excessive corrosion
C. Uneconomic LMTD
D. Decrease in heat exchanger efficiency
