250+ TOP MCQs on Combined Power Plant and Answers

Steam and Gas Turbines Multiple Choice Questions on “Combined Power Plant”.

1. Gas and Steam turbine combined power plant produces more electricity than traditional power plants by how much percent?
a) 25
b) 40
c) 50
d) The given statement was false
Answer: c
Clarification: When steam and gas turbines are jointly used in power plants and the power produced by gas and steam turbines is used in producing electricity.

2. Marine compound power plants are also the combined gas and steam power plants.
a) True
b) False
Answer: a
Clarification: Combined gas and steam power plants is the name given to marine power plants.

3. Maximum supplementary firing means _________
a) minimum fuel that can be fired
b) maximum fuel that can fired with the oxygen available in turbine
c) maximum fuel that can be fired in given time
d) none of the mentioned
Answer: b
Clarification: Maximum supplementary firing means maximum fuel that can be fired with the oxygen available.

4. Due to the limits, upper efficiency of steam turbines is fixed to _________
a) 10-15%
b) 25-45%
c) 20-40%
d) 35-45%
Answer: d
Clarification: In steam and gas turbine combined power plants, steam turbines water is used as working medium. High pressure and high temperatures are required for these high pressures which in turn requires high strengths so expensive alloys like nickel and cobalt are used. These limit the upper efficiency to 35-45%.

5. How many sections does waste heat recovery boiler have in steam generators?
a) 1
b) 2
c) 3
d) 4
Answer: c
Clarification: In steam generators waste heat recovery boilers have 3 sections. They are
Economiser
Evaporator
Superheater.

6. Turbines that are run by exhaust gases are called _______
a) power recovery turbines
b) stepped turbines
c) turbo compounded engine
d) none of the mentioned
Answer: a
Clarification: Turbines that are run by exhaust gases are called power recovery turbines.

7. Combination of two or more thermodynamic processes gives _________
a) decrease in efficiency
b) increase in efficiency
c) increases the temperature at exhaust
d) none of the mentioned
Answer: b
Clarification: When two or more thermodynamic cycles work together their overall combined efficiency increases by 50-60%.

8. By using combined cycle steam and gas power plant _________
a) specific fuel consumption can be decreased
b) efficiency increased
c) specific fuel consumption can be decreased and efficiency increased
d) none of the mentioned
Answer: c
Clarification: If specific fuel consumption is decreased it indirectly increases efficiency.

9. What are turbo-compound engines?
a) Turbines run at exhausts of Otto and diesel cycles
b) Combination of turbofan and turbojet engines
c) Combination of turboprop and turbofan engines
d) None of the mentioned
Answer: a
Clarification: Turbo compound engines are used in air-crafts where turbines run at exhausts of Otto and diesel cycles.