1. The optimum reheat pressure for most of the modern power plants is ___________ of the initial steam pressure.
a) 0.1-0.5
b) 0.2-0.3
c) 0.2-0.25
d) 0.25-0.3
Explanation: In this range of reheat pressure efficiency is maximum.
2. What is the effect of reheat on steam quality?
a) increases
b) decreases
c) does not change
d) depends on several parameters
Explanation: Because this steam is undergoing expansion two times
3. What should be the dryness fraction at the time of exhaust?
a) 0.88
b) 0.80
c) 0.90
d) 0.75
Explanation: For modern turbines the admissible dryness fraction of exhaust steam (at the turbine exit) should be not less than x = 0.86 to 0.88.
4. Reheat is preferred for the plants having efficiency greater than _____________
a) 150MW
b) 200MW
c) 100MW
d) 250MW
Explanation: For producing power less than this reheat will not be economical.
5. Which one of the following is an advantage of reheat cycle?
a) the size of the Low pressure (LP) turbine blades is reduced because specific volume is reduced by 7 to 8%
b) the reheating reduce 4 to 5% fuel consumption with a corresponding reduction in the fuel handling
c) lower steam pressures and temperatures and less costly materials can be used to obtain the required thermal performance
d) all of the mentioned
Explanation: Reheat increases work output.
6. What is the basic principle of regeneration?
a) Steam after coming out of condenser is circulated to boiler
b) Steam after coming out of condenser is circulated to turbine
c) Steam after coming out of turbine is circulated to boiler
d) Two stage turbine is used
Explanation: In regeneration steam from condenser is circulated through turbine to increase steam temperature before it enters boiler.
7. Ideal regenerative rankine cycle _______
a) Increases efficiency
b) Increases work output
c) Increases the heat supplied
d) Does not effect efficiency
Explanation: Feedwater is preheated so as to decrease the fuel consumption which increases efficiency.
8.Mean temperature of heat addition is _______ due to Regeneration.
a) Decreases
b) Not effected
c) Increases
d) Varied exponentially
Explanation: Since less heat is required in the boiler so mean temperature of heat addition increases.
9. Name the coolants commonly used for fast breeder reactors?
a) Liquid metal (Na (or) Na K)
b) Helium (He)
c) Carbon dioxide
d) All of the mentioned
Explanation: Liquid metals are commonly used, in some plants He and CO2 are also used
10. Why trash rack is used?
a) To prevent the entry of debris
b) To prevent steam overflow
c) It is used as an insulter
d) Prevents back flow
Explanation: The trash rack is used to prevent the entry of debris, which might damage the turbine runners and chock up the nozzle of impulse turbine