Engineering Chemistry Multiple Choice Questions on “Boiler Feed Water”.
1. Water is mainly used in boilers for the generation of ________________
a) Power
b) Electricity
c) Steam
d) Current
Answer: c
Clarification: Water is mainly used in boilers for the generation of steam. This steam is further used in the power plants for the generation of electricity.
2. Which of the following should not be a composition of boiler-feed water?
a) Hardness should be below 0.2ppm
b) Its caustic alkalinity should lie between 0.15 to 0.45 ppm
c) Its soda alkalinity should be 0.45-1 ppm
d) Its caustic alkalinity should be 1.5-2 ppm
Answer: d
Clarification: Its caustic alkalinity should be 0.15-0.45 ppm. All the other options are correct. Hardness should be below 0.2ppm, caustic alkalinity should lie between 0.15 to 0.45 ppm and soda alkalinity should be 0.45-1 ppm.
3. Which of the following is not a result of the excess of impurity in boiler-feed?
a) Scale and sludge formation
b) Decomposition
c) Corrosion, priming and foaming
d) Caustic embrittlement
Answer: b
Clarification: Excess of impurities in boiler-feed results in scale and sludge formation, corrosion, priming, foaming and caustic embrittlement. It does not contribute to the decomposition process.
4. If the precipitate formed is soft, loose and slimy, these are __________ and if the precipitate is hard and adhering on the inner wall, it is called _____________
a) Sludges, scale
b) Scale, sludges
c) Sludges, rodent
d) Scale, rodent
Answer: a
Clarification: If the precipitate formed is soft, loose and slimy, these are sludges and if the precipitate is hard and adhering on the inner wall, it is called scale. A rodent is a small furry mammal whose teeth never stop growing.
5. Which of the following option is incorrect about the sludges?
a) Sludges are soft, loose and slimy precipitate
b) They are non-adherent deposits and can be easily removed
c) Formed generally at heated portions of the boiler
d) Can be removed by blow down operation
Answer: c
Clarification: Sludges are formed generally at colder portions of the boiler. All the other options are correct. Sludges are soft, loose and slimy precipitate, non-adherent deposits and can be easily removed by blow down operation.
6. The scales decrease the efficiency of boiler and chances of explosions are also there.
a) True
b) False
Answer: a
Clarification: The scales decrease the efficiency of boiler and chances of explosions are also there. Scale is the precipitate that is hard and adhering on the inner wall.
7. The propulsion of water into steam drum by extremely rapid, almost explosive boiling of water at the heating surface is called ___________
a) Foaming
b) Priming
c) Corrosion
d) Caustic embrittlement
Answer: b
Clarification: The propulsion of water into steam drum by extremely rapid, almost explosive boiling of water at the heating surface is called priming. Priming is necessary as it removes all the air voids from the passage of water.
8. The phenomenon during which the boiler material becomes brittle due to accumulation of caustic substances is known as ___________
a) Foaming
b) Priming
c) Corrosion
d) Caustic embrittlement
Answer: d
Clarification: The phenomenon during which the boiler material becomes brittle due to accumulation of caustic substances is known as caustic embrittlement. This can be prevented by using sodium phosphate instead of sodium carbonate as softening reagents.
9. Foaming is caused by the formation of ___________
a) Acids
b) Alcohols
c) Oils and alkalis
d) Ketones
Answer: c
Clarification: Foaming is caused by the formation of oils and alkalis. Oils and Alkalis becomes sticky and greasy on the surface and hence results in foaming.
10. Corrosion is the decay or disintegration of boiler body material either due to chemical or electrochemical reaction with environment.
a) True
b) False
Answer: a
Clarification: Corrosion is the decay or disintegration of boiler body material either due to chemical or electrochemical reaction with environment. It converts a refined metal to a more stable form, such as its oxide, hydroxide, or sulphide.