Power Plant Engineering Set 3

Mechanical Engineering

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This set of Power Plant Engineering PPE Multiple Choice Questions & Answers (MCQs) focuses on Power Plant Engineering Set 3

Q1 | A plant producing both, electrical power & process heat simultaneously is?
  • cogenital plant
  • cogenerial plant
  • cogeneration plant
  • conglomerate plant
Answer: cogeneration plant
Explaination:
cogeneration plant is defined as a plant which produces electrical power and processes heat simultaneously.
Q2 | In a back pressure turbine  
  • pressure at the exhaust from the turbine is the saturation pressure corresponding to the temperature desired in the process
  • pressure at the entrance of the turbine is the saturation pressure corresponding to the temperature desired in the process
  • pressure at the exhaust from the turbine is the saturation pressure corresponding to the pressure desired in the process
  • none of the mentioned
Answer: pressure at the exhaust from the turbine is the saturation pressure corresponding to the temperature desired in the process
Explaination:
the name back pressure turbine is given because pressure at the exhaust from the turbine is the saturation pressure corresponding to the temperature desired in the process.
Q3 | In a by-product power cycle?
  • the power is produced initially
  • power production is in the middle stages of the cycle
  • power production is after the cycle has ended
  • none of the mentioned
Answer: power production is after the cycle has ended
Explaination:
when the process steam is the basic need, and the power is produced
Q4 | In terms of cost per MW compared to condensing sets of the same power, the back pressure turbines are?
  • more expensive
  • cheaper
  • costly
  • none of the mentioned
Answer: cheaper
Explaination:
back pressure turbines are usually small with respect to their power output because they have no great volume of exhaust to cope with, the density being high. they are usually single cylinder and hence, usually cheaper in terms of cost per mw.
Q5 | Which of the following is a good medium for constant temperature heating?
  • water
  • steam
  • coolant
  • diesel
Answer: steam
Explaination:
for constant temperature heating (or drying), steam is a very good medium since isothermal condition can be maintained by allowing saturated steam to condense at that temperature and utilising the latent heat released for heating purposes.
Q6 | The cogeneration plant efficiency nCO if WT, Qi, QH represents turbine work, heat input, heat output respectively is given by?
  • nco = (wt + qi) / qh
  • nco = (wt – qi) / qh
  • nco = (wt + qh) / qi
Answer: nco = (wt + qh) / qi
Explaination:
the cogeneration plant
Q7 | If e is the electricity fraction of the total energy output, m is the electric plant efficiency and n is the steam generator efficiency; the heat added per unit total energy output is given by?
  • (1 / m) + ((1 – e) / n)
  • (1 / n) + ((1 – e) / m)
  • (1 / m) + ((1 + e) / n)
  • (1 / n) + ((1 – e) / m)
Answer: (1 / m) + ((1 – e) / n)
Explaination:
if e is the electricity fraction of the total energy output, m is the electric plant efficiency and n is the steam generator efficiency; the heat added per unit total energy output is given by?
Q8 | Which of these is not considered economical for cogeneration?
  • a high fraction of electric to total energy
  • a low fraction of electric to total energy
  • a low fraction of total energy to electric energy
  • none of the mentioned
Answer: a low fraction of electric to total energy
Explaination:
a low fraction of electric to total energy is considered as an economical condition for cogeneration. cogeneration plant is defined as a plant which produces electrical power and processes heat simultaneously.
Q9 | Which of these is a working fluid in the bottoming plant of a Brayton-Rankine combined plant?
  • mercury
  • steam
  • water
  • air
Answer: water
Explaination:
water is the bottoming fluid due to its high specific heat capacity.
Q10 | What would be the temperature of the gas in the combustion chamber?
  • 500 °c
  • 1600 °c
  • 1200 °c
  • 650 °c
Answer: 1600 °c
Explaination:
the gas in the combustion chamber is at a temperature of 1600 °c.
Q11 | What is regeneration?
  • removal of heat from compressed air between stages of compression
  • transfer of heat energy from exhaust gases to the compressed air flowing between compressor and the combustion chamber
  • to increase the temperature of partially expanded gases by burning more fuel
  • transfer of heat energy from exhaust gases to the compressed air flowing between compressor and the combustion chamber and increases the temperature of partially expanded gases by burning more fuel
Answer: transfer of heat energy from exhaust gases to the compressed air flowing between compressor and the combustion chamber
Explaination:
transfer of heat energy from exhaust gases to the compressed air flowing between compressor and the combustion chamber is called the process of regeneration.
Q12 | What is meant by inter cooling?
  • removal of heat from compressed air between stages of compression
  • transfer of heat energy from exhaust gases to the compressed air flowing between compressor and the combustion chamber
  • to increase the temperature of partially expanded gases by burning more fuel
  • none of the mentioned
Answer: removal of heat from compressed air between stages of compression
Explaination:
removal of heat from compressed air between various stages of compression is called inter cooling.
Q13 | What is the air standard cycle for a Gas- Turbine called?
  • reheat cycle
  • rankine cycle
  • brayton cycle
  • diesel cycle
Answer: brayton cycle
Explaination:
brayton cycle is an ideal air standard cycle for a gas turbine, which, like the rankine cycle, also comprises of two reversible adiabatic & two reversible isobars.
Q14 | Power is produced when the working fluid does some work on the?
  • shaft
  • fins
  • blades
  • none of the mentioned
Answer: blades
Explaination:
for the production of power, the working fluid does some work on the blades of the turbine, thereby producing power.
Q15 | A Gas Turbine is which type of combustion plant?
  • external
  • open
  • internal
  • cannot say
Answer: internal
Explaination:
since for the production of
Q16 | Which type of compressor is used in a gas turbine plant?
  • reciprocating compressor
  • screw compressor
  • multistage axial flow compressor
  • either reciprocating compressor & screw compressor
Answer: multistage axial flow compressor
Explaination:
multistage axial flow compressor is the compressor in practical usage in a gas turbine plant.
Q17 | What part or % of power developed is utilised for driving the compressor?
  • 65 %
  • 70 %
  • 55 %
  • 80 %
Answer: 65 %
Explaination:
a total of 65 % of power developed in the gas turbine is used for driving the compressor.
Q18 | The gas turbine power plant mainly uses which among the following fuels?
  • coal and peat
  • kerosene oil and diesel oil and residual oil
  • gas oil
  • natural gas and liquid petroleum fuel
Answer: natural gas and liquid petroleum fuel
Explaination:
natural gas and liquid petroleum fuel are among the two fuels used in a gas turbine.
Q19 | The maximum steam temperature in a
  • 600
  • 500
  • 300
  • 100
Answer: 600
Explaination:
the maximum steam temperature in a power cycle is 600 degree centigrade.
Q20 | The temperature in a dry bottom pulverised coal furnace, in degree Celsius is about?
  • 1200
  • 1300
  • 1400
  • 2000
Answer: 1300
Explaination:
the temperature in a dry bottom pulverised coal furnace, in degree celsius is about 1300.
Q21 | What happens to the availability in a combined cycle plant?
  • decreases
  • increases
  • remains same
  • cannot say
Answer: decreases
Explaination:
there is a great thermal irreversibility & a decrease of availability because of heat transfer from combustion gases to steam through such a large temperature difference.
Q22 | Which of the following is not a type of Combined Plant?
  • sodium- mercury-potassium plant
  • gas turbine-steam turbine plant
  • thermionic steam plant
  • thermoelectric steam plant
Answer: sodium- mercury-potassium plant
Explaination:
sodium-mercury-potassium plants have two topping fluids which is impossible for a plant to possess.
Q23 | Which of these is not a component of nuclear reactor?
  • reactor core
  • refractor
  • control rod
  • biological shield
Answer: refractor
Explaination:
a reflector rather than a refractor is a component of nuclear reactor.
Q24 | What efficiencies of thermionic power generator have been realised?
  • 50-60%
  • 40-50%
  • 10-20%
  • 30-40%
Answer: 10-20%
Explaination:
efficiency of 30-40% has been realised in thermionic generators.
Q25 | In economics of nuclear power plant taxes and insurance charges are taken as  
  • operating cost
  • maintenance cost
  • capital cost
  • fixed cost
Answer: fixed cost
Explaination:
the life of reactor plant may be taken as between 15 to 20 years. for the other parts of the plant equipment the life may be taken as 30 years. the fixed cost would be interest, depreciation, taxes and insurance charges.
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