Power Plant Engineering Set 6

Mechanical Engineering

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This set of Power Plant Engineering PPE Multiple Choice Questions & Answers (MCQs) focuses on Power Plant Engineering Set 6

Q1 | The area under the load curve represents
  • the average load on power system
  • maximum demand
  • number of units generated
  • load factor
Answer: number of units generated
Explaination:
load curve is obtained by plotting fluctuating load be keeping load on y axis and time in x axis. the area under the load curve represents the total number of units generated in a particular time.
Q2 | Which of the following is equal to the maximum demand?
  • the ratio of area under curve to the total area of rectangle
  • the ratio of area under curve and number of hours
  • the peak of the load curve
  • the area under the curve
Answer: the peak of the load curve
Explaination:
the ratio of area under curve to the total area of the rectangle is called load factor. the ratio of area under the curve to the number of hours represents the average load. the peak of the curve represents the maximum demand.
Q3 | Load duration curve indicates  
  • the variation of load during different hours of the day
  • total number of units generated for the given demand
  • total energy consumed by the load
  • the number of hours for which the particular load lasts during a day
Answer: the number of hours for which the particular load lasts during a day
Explaination:
the variation of load during different hours of the day is shown by load curve. load duration curve is different from load curve. load duration curve indicates the variation of the load, but with the load arranged in descending order of magnitude.
Q4 | During which time the demand of electrical energy is maximum?
  • 2 a.m. to 5 a.m.
  • 5 a.m. to 12 p.m.
  • 12 p.m. to 7 p.m.
  • 7 p.m. to 9 p.m
Answer: 7 p.m. to 9 p.m
Explaination:
from the load curve it is obtained that during early morning demand is always low. around 5 a.m. it starts increasing and around 9 a.m. load reaches a high value and remains almost constant till evening except for some dip during lunch hours. the load again starts increasing in evening hours and reaches its peak around 7 to 9 p.m.
Q5 | Size and cost of installation depends upon
  • average load
  • maximum demand
  • square mean load
  • square of peak load
Answer: maximum demand
Explaination:
the greatest of all “short time interval averaged” during a given period, on the power system is called the maximum demand. maximum demand represents the maximum amount of load that is active, out of total connected load. so the size and rating of power plant depends on maximum demand.
Q6 | What is Demand factor?
  • ratio of connected load to maximum demand
  • ratio of average load to connected load
  • ratio of maximum demand to the connected load
  • ratio of kilowatt hour consumed to 24 hours
Answer: ratio of maximum demand to the connected load
Explaination:
demand factor is the ratio of actual maximum demand on the system to the total load connected to the system. the idea of demand factor was introduced due to the fact that all the equipments connected to the
Q7 | The load factor is  
  • always less than unity
  • less than or greater than 1
  • always greater than 1
  • less than zero
Answer: always less than unity
Explaination:
load factor is the ratio of average demand to the maximum demand. average demand can not be greater than maximum demand. so the value of load factor is always less than unity.
Q8 | In practice what is the value of diversity factor?
  • less than unity
  • geater than unity
  • equal to or greater than unity
  • less than zero
Answer: geater than unity
Explaination:
maximum demand of different consumers never occurs at a time, due to this the total maximum demand of the load is always less than sum of individual maximum
Q9 | Which of the following is called as cold reserve?
  • reserve capacity available but not ready for use
  • reserve capacity available and ready for use
  • generating capacity connected to bus and ready to take load
  • capacity in service in excess of peak load
Answer: reserve capacity available but not ready for use
Explaination:
cold reserve is the generating capacity which is available for service but not normally ready for immediate loading.
Q10 | How are moderate active solid wastes disposed?
  • buried underground
  • buried under sea
  • sent to outer space
  • left out in streams or rivers
Answer: buried underground
Explaination:
in a nuclear fuel cycle, the solid, liquid and gaseous radioactive wastes are produced at different stages. these radioactive wastes must be disposed off in such a manner that there is no hazard to the human and plant life. moderate active solid wastes are buried in the ground.
Q11 | Moderate liquid nuclear wastes are disposed into  
  • deep pits
  • buried underground
  • left into rivers
  • left into deep oceans
Answer: deep pits
Explaination:
moderate liquid wastes after preliminary treatments are discharged in deep pits or day well from which they sweep out into the surrounding. certainly liquid wastes are mixed with some kind of other chemical in order to lower their radioactivity.
Q12 | How are active liquids of nuclear waste disposed?
  • stored in concrete tanks and buried underground
  • stored in concrete tanks and buried in sea
  • mixed with other chemicals and left into free atmosphere
  • they are reused and burnt away in gaseous fumes
Answer: stored in concrete tanks and buried underground
Explaination:
active liquids are kept in concrete tanks and these tanks are buried in the ground till their decay of radio activity. many times the radio activity increases the temperature of the liquid waste or sometimes these liquids boil and the activity decreases with time.
Q13 | Can vacated coal mines be used for waste disposal.
  • true
  • false
Answer: true
Explaination:
yes, vacated coal mines can be used for waste disposal. the wastes are disposed in the salt heaps provided in the mines, because salt is a powerful absorber of radioactive emissions. it will be easy and more economical method to dispose of liquid waste by freezing.
Q14 | How is High Level solidified nuclear wastes (HLW) stored?
  • concrete tanks
  • canisters
  • packed rock salt
  • soil bins
Answer: canisters
Explaination:
the solidified waste is placed in canisters that are stored in holes formation
Q15 | Absorption of radioactive element by human, affects their offspring’s.
  • true
  • false
Answer: true
Explaination:
absorption of neutron or radioactive element by a tissue nucleus leads to radioactive nucleus which results change in chemical nature, mal-functioning of cell. due to this, cell damages leading to genetic modification. inhale of radioactive material through air, food and water result radiation hazard.
Q16 | For how many days is radioactive solid waste kept is kept under water at 6m deep for initial cooling?
  • 15 days
  • 50 days
  • 30 days
  • 100 days
Answer: 100 days
Explaination:
it is necessary to keep the radioactive solid waste first in the water of 6m depth nearly for 100 days. it was found that after 100 days cooling of radioactive waste of 28mw plant in water still has a radioactivity equal to million grams of radium. about 50% radioactive elements disappear during cooling.
Q17 | What are released into biosphere from nuclear power plants?
  • gaseous effluents
  • waste product
  • smoke
  • the obtained product
Answer: gaseous effluents
Explaination:
under normal operation, gaseous effluents are released slowly from the power plants into the biosphere and become diluted and dispersed harmlessly. releasing at slow rates gives it time to blow of slowly.
Q18 | Tailings forms are the residues from
  • uranium
  • thorium
  • cadmium
  • boron
Answer: uranium
Explaination:
tailings are residues from uranium mining and milling operations. they contain low concentration of naturally occurring radioactive materials. they are generated in large volumes and are stored at the mine or mill sites.
Q19 | LLW stands for  
  • low level water
  • low laser width
  • low level waste
  • loss of levels in water
Answer: low level waste
Explaination:
low level waste contains less than 10 nci per gram of transuranium contaminants containing low but potentially hazardous concentrations of radioactive materials. these are generated in almost all activities involving radioactive materials, require little or no shielding.
Q20 | What is the unit of Heat rate?
  • kj/kw
  • kw/kj
  • kj
  • kw
Answer: kj/kw
Q21 | Rankine efficiency of a Steam Power Plant
  • improves in summer as compared to that in winter
  • improves in winter as compared to that in summer
  • is unaffected by climatic conditions
  • none of the mentioned
Answer: improves in winter as compared to that in summer
Q22 | Which of the following contributes to the improvement of efficiency of Rankine cycle in a Thermal Power Plant?
  • reheating of steam at intermediate stage
  • regeneration use of steam for heating boiler feed water
  • use of high pressures
  • all of the mentioned
Answer: all of the mentioned
Q23 | What is the actual turbine inlet temperature in Rankine cycle?
  • 700c
  • 800c
  • 550c d) 1150c
Answer: 550c d) 1150c
Q24 | Rankine cycle efficiency of a good Steam Power Plant may be in the range of?
  • 15 to 20%
  • 35 to 45%
  • 70 to 80%
  • 90 to 95%
Answer: 35 to 45%
Q25 | A simple Rankine cycle operates the Boiler at 3 MPa with an outlet temperature of 350°C and the Condenser at 50 kPa. Assuming ideal operation and processes, what is the thermal efficiency of this cycle?
  • 7.7
  • 17.7
  • 27.7
  • 37.7
Answer: 27.7
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