Engineering Questions with Answers - Multiple Choice Questions
Food Engineering MCQ’s – Unit Operations – Crystallization-2
1 - Question
Statement 1: Forced circulation liquid evaporator-crystallizer has good CSD control.
Statement 2: Draft tube baffle crystallizer is flash evaporated for crystallization.
a) True, False
b) True, True
c) False, False
d) False, True
View Answer
Explanation: Draft tube baffle crystallizer has good CSD control. Forced circulation liquid evaporator-crystallizer is flash evaporated for crystallization.
2 - Question
Work of Draft tube in Draft tube baffle crystallizer is _____
a) Maintaining good circulation rate for slurry
b) Reducing energy requirement for mixing
c) Maintaining good circulation rate for slurry & reducing energy requirement for mixing
d) None of the mentioned
View Answer
Explanation: Work of Draft tube in Draft tube baffle crystallizer is maintaining good circulation rate for slurry and reducing energy requirement for mixing.
3 - Question
Advantage of Draft tube baffles crystallizer _____
a) Re-circulation of a small fraction of mother liquor
b) Selectively separates big particles from the smaller ones
c) All of the mentioned
d) None of the mentioned
View Answer
Explanation: Advantage of Draft tube baffles crystallizer is that it re-circulates a large fraction of mother liquor and selectively separates big particles from the smaller ones.
4 - Question
Secondary nucleation involves the collision of crystals.
a) True
b) False
View Answer
Explanation: Secondary nucleation involves the collision of crystals.
5 - Question
Draft tubes _____ crystal-crystal attrition. Crystals _____ bottom.
a) Increase, should be kept on
b) Increase, should be kept off
c) Decrease, should be kept on
d) Decrease, should be kept off
View Answer
Explanation: Draft tubes decrease crystal-crystal attrition. Crystals should be kept off bottom so as to encourage crystal growth.
6 - Question
High residence time encourages _____
a) Attrition
b) Crystal growth
c) Attrition & Crystal growth
d) None of the mentioned
View Answer
Explanation: High residence time encourages attrition.
7 - Question
Heating on the surface of a heat exchanger leads to fouling.
a) True
b) False
View Answer
Explanation: Heating on the surface of a heat exchanger leads to fouling. Hence surface heating shouldn’t be done.
8 - Question
What does excess supersaturating followed by cooling lead to?
a) Primary nucleation
b) Secondary nucleation
c) Both, nucleation and crystal growth in general
d) None of the mentioned
View Answer
Explanation: Excess supersaturating followed by cooling only leads to primary nucleation. That’s like the formation of only the first crystal. Secondary nucleation is due to the agglomeration of crystals which is desirable.
9 - Question
Excess nucleation leads to _____
a) Non-uniform CSD
b) In huge capacity vessels, the crystal-crystal attrition leads to formation of small size particles hence no crystallization
c) Non-uniform CSD, in huge capacity vessels, the crystal-crystal attrition leads to formation of small size particles hence no crystallization
d) None of the mentioned
View Answer
Explanation: Excess nucleation leads to both of the mentioned.
10 - Question
Incrustation leads to _____
a) Affects safety
b) Damages equipment
c) Affects product quality
d) All of the mentioned
View Answer
Explanation: Incrustation leads to all of the mentioned.
11 - Question
Statement 1: Incrustation may lead to under deposit-corrosion.
Statement 2: Scrapers can be used as an agitated medium to avoid incrustation.
a) True, False
b) True, True
c) False, False
d) False, True
View Answer
Explanation: Incrustation may lead to under deposit-corrosion. Scrapers can be used as an agitated medium to avoid incrustation.
12 - Question
Automated valves should be avoided.
a) True
b) False
View Answer
Explanation: Automated valves should be avoided because they become inoperative at excessive temperatures and high solid contents.
13 - Question
Statement 1: T-joints in pipelines for crystallization should be avoided as much as possible.
Statement 2: Thin liquids should have a slope to drain off liquid.
a) True, False
b) True, True
c) False, False
d) False, True
View Answer
Explanation: T-joints in pipelines for crystallization should be avoided as much as possible. Thin liquids should have a slope to drain off liquid. Both the points to be done to prevent incrustation.
14 - Question
In making of cocoa butter via crystallization, liquid is the desired product.
a) True
b) False
View Answer
Explanation: In the making of cocoa butter from kernel oil via crystallization, solid is the desired product.
15 - Question
Which of the following needs to be taken care of during scale up of crystallizers?
a) Reynolds number
b) Residence time
c) Power supplied to agitator per unit volume
d) All of the mentioned
View Answer
Explanation: All of the mentioned needs to be taken care of during scale up of crystallizers.