This set of Power Plant Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Feedwater Heaters”.
1. Feedwater heaters are of two types, they are
a) natural and forced
b) saturated and non saturated
c) open and close
d) water driven and steam driven
Explanation : Feedwater heaters are classified by the methods of mixing steam and feedwater.
2. In open feedwater heater
a) the extracted steam is allowed to mix with feedwater
b) feedwater flows trough tubes and steam is condensed outside
c) steam flows outside tubes and feedwater inside
d) steam flows inside tubes and outside inside
Explanation : In a closed heater, the extracted steam is allowed to mix with feedwater and both leave the heater at a common temperature.
3. Closed heaters are also called
a) contact type heater
b) shell and heat exchanger
c) drip heaters
d) shell and tube heater
Explanation : Closed heaters are also called shell and heat exchanger where the feedwater flows through the tubes.
4. Expand TTD?
a) turbine temperature difference
b) total temperature difference
c) terminal temperature difference
d) turbine terminal difference
Explanation : Terminal temperature difference = saturation temperature of bled steam – exit water temperature.
5. The value of TTD varies with?
a) heater pressure
b) heater temperature
c) turbine inlet temperature
d) independent of all mentioned
Explanation : The value of TTD varies with heater pressure. heaters receiving wet steam, the TTD is positive.
6. Why at least one open heater is used?
a) installed vertically
b) feedwater deaeration
c) less cost
d) increase efficiency
Explanation : The open heater works as a deaerator.
7. What are the advantages of open heater?
a) lower cost
b) high heat transfer capacity
c) high feedwater temperature
d) all of the mentioned
Explanation : Open heaters are cheap as compared to closed heaters, in closed heaters feedwater temperature is not high.
8. What do you mean by heater drip?
b) heater failure
d) maximum temperature
Explanation : Saturated water at the steam extraction pressure.
9. Which of the following material can be used as a moderator?
c) Heavy water
d) all of the mentioned
Explanation : A neutron moderator is a medium that reduces the speed of fast neutrons, thereby turning them into thermal neutrons capable of sustaining a nuclear chain reaction involving uranium-235.
10. Closed heaters are?
d) depends on requirement
Explanation : Closed heaters are mostly horizontal. Sometimes, they are made vertical to reduce the floor areas.
Sanfoundry Global Education & Learning Series – Power Plant Engineering.
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