Power Plant Questions and Answers for Experienced people on “Gas Turbine-Steam Power Plant – III”.
1. In gas turbine, intercooler is placed _____________
a) before low pressure compressor
b) in between low pressure compressor and high pressure compressor
c) in between high pressure compressor and turbine
d) none of the mentioned
Answer: b
Clarification: The various methods to improve the efficiency of open cycles include intercooling the feed water from the compressor to the turbine and then employing regeneration & reheat to just use the power of the reheated water in order to maximize the power output. Here, this is done by placing the intercooler before any of the above processes.
2. In gas turbine, what is the function of Re-heater?
a) Heat inlet air
b) Heat exhaust gases
c) Heat air coming out of compressor
d) Heat gases coming out of high pressure turbine
Answer: d
Clarification: In order to make a thermodynamic process of larger efficiency, it is shifted towards isothermal behavior. For this, the output from re-generator, which is at a higher temperature is cooled to the temperature which is mid-way between the two temperature ranges. Then, it is again heated to the final temperature thereby increasing the efficiency of the cycle.
3. The ‘work ratio’ increases with _____________
a) increase in turbine inlet pressure
b) decrease in compressor inlet temperature
c) decrease in pressure ratio of the cycle
d) all of the mentioned
Answer: d
Clarification: The ‘work ratio’ increases when the turbine inlet pressure increases, the compressor inlet temperature decreases, the pressure ratio of the cycle decreases.
4. In the centrifugal compressor, total pressure varies _____________
a) directly as the speed ratio
b) square of speed ratio
c) cube of the speed ratio
d) all of the mentioned
Answer: b
Clarification: The total pressure in a centrifugal compressor is a function of speed ratio. It varies square of the speed ratio.
5. The efficiency of multistage compressor is _____ than a single stage.
a) lower
b) higher
c) equal to
d) all of the mentioned
Answer: a
Clarification: The efficiency of multistage compressor is lower than a single stage.
6. In centrifugal compressor, power input varies as _________
a) directly as the speed ratio
b) the square of speed ratio
c) the cube of the speed ratio
d) all of the mentioned
Answer: c
Clarification: Power output in a centrifugal compressor varies as the cube of the speed ratio.
7. In the ____________ heat transfer takes place between the exhaust gases and cool air.
a) Intercooler
b) Re-heater
c) Regenerator
d) Compressor
Answer: c
Clarification: The process of heat transfer between the exhaust gases and cool air takes place in Regenerator.
8. In centrifugal compressor, the diffuser converts _________
a) Kinetic energy into pressure energy
b) Pressure energy into Kinetic energy
c) Kinetic energy into Mechanical energy
d) Mechanical energy into Kinetic energy
Answer: a
Clarification: The diffuser of a centrifugal compressor converts Kinetic Energy into Pressure energy.
Power Plant for Experienced people, <