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Multiple choice question for engineering

Set 1

1. Presence of free moisture in coal is most disadvantageous during
a) combustion of fire slacks on the grates
b) its pulverisation
c) handling (e.g. when emptying wagons)
d) none of the mentioned

View Answer

Answer: b [Reason:] As pulverisation of coal is a power consuming process, the presence of free moisture in coal is most disadvantageous.

2. Abrasion index of blast furnace coke should be around __________ percent.
a) 20
b) 35
c) 80
d) 55

View Answer

Answer: c [Reason:] Abrasion index of blast furnace coke should be around 80 percent. More this abrasion index, which is an indicator of Abrasion; more is the combustibility.

3. Which of the following petrographic constituents of coal is non-coking?
a) Durain
b) Vitrain
c) Clarain
d) Fussain

View Answer

Answer: d [Reason:] Among the mentioned petrographic constituents, Fussain is non-coking.

4. ‘Fat’ coal means a coal having
a) low ash content
b) non-smoking tendency
c) high volatile matter
d) low calorific value

View Answer

Answer: c [Reason:] ‘Fat’ coal means a coal having high volatile matter.

5. Initial pressure of oxygen introduced into the ‘bomb’ of the bomb calorimeter for determination of calorific value of coal/fuel oil may be around __________ atm.
a) 20-30
b) 60-65
c) 95-100
d) 3-5

View Answer

Answer: a [Reason:] Initial pressure of oxygen introduced into the ‘bomb’ of the bomb calorimeter for determination of calorific value of coal/fuel oil may be around 20-30 atm.

6. Proximate analysis of coal determines its __________ content.
a) moisture, ash, sulphur & volatile matter
b) moisture, volatile matter, ash & fixed carbon
c) moisture, sulphur, nitrogen & fixed carbon
d) none of the mentioned

View Answer

Answer: b [Reason:] Proximate analysis of coal determines its moisture, volatile matter, ash & fixed carbon content.

7. If the specific heat of gaseous products of combustion of a fuel is high, the abiabatic flame temperature will be
a) very high, if the fuel is of low calorific value
b) low
c) high
d) none of the mentioned

View Answer

Answer: b [Reason:] If the specific heat of gaseous products of combustion of a fuel is high, the abiabatic flame temperature will below.

8. “Overfire burning” in a furnace is a phenomenon characterised by the
a) burning of carbon monoxide and other incombustibles in upper zone of furnace by supplying more air
b) supply of excess fuel
c) supply of excess air
d) none of the mentioned

View Answer

Answer: a [Reason:] “Overfire burning” in a furnace is a phenomenon characterised by the burning of carbon monoxide and other incombustibles in upper zone of furnace by supplying more air.

9. Atomising steam to fuel oil ratio in a burner should be around
a) 0.5
b) 1.5
c) 2.5
d) 3.5

View Answer

Answer: a [Reason:] A low atomising fuel oil ratio is favourable enough to ensure good combustion.

10. Presence of free moisture in coal during its high temperature carbonisation
a) increases the loss of fine coal dust from the ovens when charging
b) protects the volatile products from pyrolysis (cracking) in the presence of hot coke and hot oven walls
c) reduces the coking time
d) none of the mentioned

View Answer

Answer: b [Reason:] The presence of free moisture in coal during its high temperature carbonisation protects the volatile products from pyrolysis (cracking) in the presence of hot coke and hot oven walls.

Set 2

1. Which of the following is not considered a type of coal according to ASTM?
a) anthracite
b) bituminous
c) peat
d) lignite

View Answer

Answer: c [Reason:] Because peat contains 90% of moisture and hence is not suitable as utility fuel.

2. Which of the following is not directly determined in the Proximate Analysis of coal?
a) Volatile Matter
b) Fixed Carbon
c) Moisture
d) Ash

View Answer

Answer: b [Reason:] Fixed carbon is the difference between 100% and sum of the percentages of volatile matter, moisture and ash.

3. Which of these is not a component of coal in Ultimate Analysis?
a) carbon
b) sulphur
c) ash
d) phosphor

View Answer

Answer: d [Reason:] This component is not determined in Ultimate Analysis.

4. If M and A represent the percentages of moisture and ash respectively, the dry and ash free analysis in Ultimate Analysis is obtained on dividing other components by the fraction of
a) {1-(M+A)}/100
b) {1-(M-A)}/100
c) {1-(A-M)}/100
d) 1-{(M+A)/100}

View Answer

Answer: d [Reason:] The fraction of ash and moisture is given by (M+A)/100. So the dry and ash free part is 1-{(M+A)/100}.

5. The extent of caking in coal is determined using
a) swelling index
b) grindability
c) weatherability
d) heating value

View Answer

Answer: a [Reason:] Swelling index is the quantitative evaluation method devised to determine the extent of calling in coal.

6. Coke devoid of volatile matter is called
a) caking coal
b) free-burning coal
c) agglomerate
d) coke

View Answer

Answer: d [Reason:] Coke is the type of coal devoid of volatile matter.

7. Which of the following property is the inverse of the power required to grind coal to a particular size for burning?
a) heating value
b) weatherabillity
c) grindability
d) sulphur content

View Answer

Answer: c [Reason:] This property of coal is measured by the standard Grindability Index.

8. The design of steam generator greatly depends on
a) spontaneous combustion
b) sulphur content
c) ash softening temperature
d) heating value

View Answer

Answer: c [Reason:] The ash softening temperature is the temperature at which ash becomes plastic. If the furnace temperature is higher, ash forms molten slag and causes trouble in discharge.

Set 3

1. Having two separate units for process heat and power is?
a) useful
b) useless
c) pollution reducing
d) none of the mentioned

View Answer

Answer: b [Reason:] Having two separate units for process heat & power is wasteful, for of the total heat supplied to the steam generator for power purposes, a greater part will normally be carried away by the cooling water in the condenser.

2. A plant producing both, electrical power & process heat simultaneously is?
a) Cogenital plant
b) Cogenerial plant
c) Cogeneration plant
d) Conglomerate plant

View Answer

Answer: c [Reason:] Cogeneration plant is defined as a plant which produces electrical power and processes heat simultaneously.

3. In a back pressure turbine?
a) pressure at the exhaust from the turbine is the saturation pressure corresponding to the temperature desired in the process
b) pressure at the entrance of the turbine is the saturation pressure corresponding to the temperature desired in the process
c) pressure at the exhaust from the turbine is the saturation pressure corresponding to the pressure desired in the process
d) none of the mentioned

View Answer

Answer: a [Reason:] 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.

4. In a by-product power cycle?
a) the power is produced initially
b) power production is in the middle stages of the cycle
c) power production is after the cycle has ended
d) none of the mentioned

View Answer

Answer: c [Reason:] When the process steam is the basic need, and the power is produced incidentally as a by-product, the cycle is often called as the by-product power cycle.

5. Back pressure turbines are usually _________________ with respect to their power output.
a) large
b) small
c) very large
d) very small

View Answer

Answer: b [Reason:] 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.

6. In terms of cost per MW compared to condensing sets of the same power, the back pressure turbines are?
a) more expensive
b) cheaper
c) costly
d) none of the mentioned

View Answer

Answer: b [Reason:] 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.

7. Which of these is not an application of back pressure turbine?
a) desalination of sea water
b) filtration of water
c) process industries
d) petrochemical installations

View Answer

Answer: b [Reason:] The applications of back pressure turbine are desalination of sea water, process industries, petrochemical installations, district heating and also for driving compressors and feed pumps.

8. Back pressure turbine is placed between?
a) Turbine & Pump
b) Boiler & Pump
c) Turbine & Heat Exchanger
d) Boiler & Turbine

View Answer

Answer: d [Reason:] In a cogeneration plant, the back pressure turbine is placed between the boiler & turbine.

9. Which of the following is a good medium for constant temperature heating?
a) Water
b) Steam
c) Coolant
d) Diesel

View Answer

Answer: b [Reason:] 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.

10. The cogeneration plant efficiency nco if WT, Qi, QH represents turbine work, heat input, heat output respectively is given by?
a) nCO = (WT + Qi) / QH
b) nCO = (WT – Qi) / QH
c) nCO = (WT + QH) / Qi
d) nCO = (WT + QH) / Qi

View Answer

Answer: d [Reason:] The cogeneration plant efficiency nco if WT, Qi, QH represents turbine work, heat input, heat output respectively is, nCO = (WT + QH) / Qi.

11. The electricity fraction of total energy output if W1 and Q1 represents the turbine work and heat output is given by?
a) W1 / (W1 + Q1)
b) W1 / (W1 – Q1)
c) W1 / (W1Q1)
d) W1 / Q1

View Answer

Answer: a [Reason:] The electricity fraction of total energy output if W1 and Q1 represents the turbine work and heat output is, W1 / (W1 + Q1).

12. 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?
a) (1 / m) + ((1 – e) / n)
b) (1 / n) + ((1 – e) / m)
c) (1 / m) + ((1 + e) / n)
d) (1 / n) + ((1 – e) / m)

View Answer

Answer: a [Reason:] 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).

13. Pass-out turbines are used in which of these cases?
a) relatively high back pressure
b) small heating requirement
c) only a
d) both a and b

View Answer

Answer: d [Reason:] Pass-out turbines are used in cases of relatively high back pressure and small heating requirements. They are used in cases where a certain quantity of steam is continuously extracted from the turbine at an intermediate stage for heating purposes at the desired temperature and pressure.

14. Which of these is not considered economical for cogeneration?
a) a high fraction of electric to total energy
b) a low fraction of electric to total energy
c) a low fraction of total energy to electric energy
d) none of the mentioned

View Answer

Answer: b [Reason:] 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.

Set 4

1. The maximum steam temperature in a power cycle in degree centigrade is?
a) 600
b) 500
c) 300
d) 100

View Answer

Answer: a [Reason:] The maximum steam temperature in a power cycle is 600 degree centigrade.

2. The temperature in a dry bottom pulverised coal furnace, in degree Celsius is about?
a) 1200
b) 1300
c) 1400
d) 2000

View Answer

Answer: b [Reason:] The temperature in a dry bottom pulverised coal furnace, in degree Celsius is about 1300.

3. What happens to the availability in a combined cycle plant?
a) decreases
b) increases
c) remains same
d) cannot say

View Answer

Answer: a [Reason:] 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.

4. By superposing a high temperature power plant as a topping unit to the steam plant, the energy conversion efficiency achieved is?
a) higher
b) lower
c) maximum
d) minimum

View Answer

Answer: a [Reason:] By superposing a high temperature power plant as a topping unit to the steam plant, the energy conversion efficiency achieved is higher from fuel to electricity.

5. Which of the following is not a type of Combined Plant?
a) Sodium- mercury-Potassium plant
b) Gas turbine-Steam turbine plant
c) Thermionic steam plant
d) Thermoelectric steam plant

View Answer

Answer: a [Reason:] Sodium-mercury-potassium plants have two topping fluids which is impossible for a plant to possess.

6. Which of these is not a component of nuclear reactor?
a) reactor core
b) refractor
c) control rod
d) biological shield

View Answer

Answer: b [Reason:] A reflector rather than a refractor is a component of nuclear reactor.

7. Which of these is not a merit of nuclear power?
a) amount of fuel required is small
b) plant requires a huge amount of area
c) demand for coal and oil is reduced
d) most economical in large quantities

View Answer

Answer: b [Reason:] A small amount of area is required.

8. The thermionic generator is essentially which kind of device?
a) low voltage & high current
b) high voltage & high current
c) low voltage & low current
d) high voltage and high current

View Answer

Answer: a [Reason:] Thermionic generator is essentially a low-voltage & high-current device.

9. What efficiencies of thermionic power generator have been realised?
a) 50-60%
b) 40-50%
c) 10-20%
d) 30-40%

View Answer

Answer: c [Reason:] Efficiency of 30-40% has been realised in thermionic generators.

10. The maximum electron current per unit area provided by an emitter is given by (where J=current density, T=absolute temperature in K, ɸ=work function in keV, k=Boltzmann’s constant & A=emission constant)
a) J= AT exp(-ɸ/kT)
b) J= AT (-ɸ/kT)
c) J= AT2 exp(-ɸ/kT)
d) J= exp(-Aɸ/kT2)

View Answer

Answer: c [Reason:] The maximum current density is given by Richardson-Dushman equation.

11. In an electron beam, the average kinetic energy of an electron is given by
a) 2KT
b) 3KT
c) 1.5KT
d) 2.5KT

View Answer

Answer: a [Reason:] The average kinetic energy is equal to 2KT.

Set 5

1. The mercury steam cycle represents how many coupled Rankine cycles?
a) 1
b) 2
c) 3
d) 4

View Answer

Answer: b [Reason:] The mercury steam cycle represents 2 fluid cycles where 2 Rankine cycles have been coupled in series.

2. In the mercury steam cycle, the mercury cycle is called?
a) bottoming cycle
b) middle cycle
c) topping cycle
d) none of the mentioned

View Answer

Answer: c [Reason:] The mercury steam cycle has the mercury cycle as the topping cycle.

3. In the mercury steam cycle, the steam cycle is called?
a) bottoming cycle
b) middle cycle
c) topping cycle
d) none of the mentioned

View Answer

Answer: a [Reason:] The mercury steam cycle has the steam cycle as the bottoming cycle.

4. Apart from mercury & steam, which of these is a component of tertiary cycle?
a) nitrogen di-oxide
b) water
c) carbon di-oxide
d) sulphur di-oxide

View Answer

Answer: d [Reason:] The tertiary cycle is mercury-steam-sulphur dioxide cycle.

5. The addition of sulphur dioxide in a tertiary cycle is at?
a) high temperature
b) low temperature
c) too high temperature
d) none of the mentioned

View Answer

Answer: b [Reason:] The tertiary cycle is mercury-steam-sulphur dioxide cycle. Here, addition of sulphur dioxide is at low temperature.

6. Which of these can also be used as a topping fluid?
a) Sodium
b) Calcium
c) Boron
d) Titanium

View Answer

Answer: a [Reason:] Apart from mercury, only Sodium or Potassium are suitable enough to be used as a topping fluid.

7. Which of these can be used as a fluid in the bottoming fluid?
a) Mercury
b) Ammonia
c) Calcium
d) Sodium

View Answer

Answer: b [Reason:] Apart from Sulphur dioxide, Ammonia is the most suitable bottoming fluid.

8. In case of Sodium-mercury-steam cycle, which is the topping fluid?
a) Mercury
b) Steam
c) Sodium
d) Cannot say

View Answer

Answer: c [Reason:] Apart from mercury, only Sodium or Potassium are suitable enough to be used as a topping fluid. Here, mercury is not a topping fluid so naturally, sodium becomes the topping fluid.

9. In case of mercury-steam-sulphur dioxide cycle, which is the bottoming fluid?
a) Mercury
b) Steam
c) Sulphur dioxide
d) Cannot say

View Answer

Answer: c [Reason:] Sulphur dioxide, being the only bottoming fluid in the tertiary cycle is used as a bottoming fluid.

10. The total loss in a tertiary cycle is?
a) sum of losses in the individual cycles
b) product of losses in the individual cycles
c) sum of products of individual losses
d) none of the mentioned

View Answer

Answer: b [Reason:] The total loss in a tertiary cycle is product of losses in the individual cycles.