Fuels & Combustion ( Power Plant Engineering ) MCQs – Mechanical Engineering MCQs
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Mechanical Engineering MCQs – Fuels & Combustion ( Power Plant Engineering ) MCQs
The most occurred mcqs of ( ) in past papers. Past papers of Fuels & Combustion ( Power Plant Engineering ) Mcqs. Past papers of Fuels & Combustion ( Power Plant Engineering ) Mcqs . Mcqs are the necessary part of any competitive / job related exams. The Mcqs having specific numbers in any written test. It is therefore everyone have to learn / remember the related Fuels & Combustion ( Power Plant Engineering ) Mcqs. The Important series of Fuels & Combustion ( Power Plant Engineering ) Mcqs are given below:
Fuel Oil
1. The bulk of hydrocarbon belongs to which group?
a) paraffin
b) isoparaffin
c) cycloparaffin
d) aromatic
Answer: a
Explanation: A bulk of hydrocarbons in fuel oils belongs to paraffin series like methane, ethane.
2. Which of these is not a lighter fraction of fuel oil?
a) gasoline
b) aviation fuel
c) heavy diesel oil
d) boiler fuel
Answer: d
Explanation: Boiler fuel is one of the heavier fraction in the refining process of fuel oil.
3. Which of these properties specifies the minimum temperature at which fuel oil can be ignited?
a) pour point
b) flash point
c) heating value
d) viscosity
Answer: b
Explanation: The flash point is the minimum temperature at which fuel may be ignited.
4. Which of the following type of fuel does not contain ash?
a) coal
b) fuel oil
c) natural gas
d) synthetic fuels
Answer: c
Explanation: Because of its gaseous nature, natural gas is the cleanest of all fuel types as it does contain ash and also produces no smoke on combustion.
5. Which of these gases is the reason for the maintenance of natural gas at cryogenic temperatures?
a) methane
b) ethane
c) propane
d) benzene
Answer: a
Explanation: The major component of natural gas is methane, whose critical temperature is -83C . So cryogenic temperatures are needed to maintain them it in liquid state at moderate pressure.
6. The gas which contributes maximum to heating value of natural gas is?
a) CO
b) CO2
c) H2
d) CH4
Answer: d
Explanation: CH4 gas contributes maximum to the heating value of natural gas.
7. A coal containing high percentage of durian is called _________
a) splint
b) bright
c) boghead
d) non-banded
Answer: a
Explanation: Coal containing high percentage of durian is called splint.
8. Low temperature carbonisation _________
a) produces less quantity of tar than high temperature carbonisation
b) is mainly producing smokeless domestic coke
c) is meant for production of ‘metallurgical coke’
d) produces higher temperature gas than high temperature carbonisation
Answer: b
Explanation: During this process, the fuel is broken down into solid residue called semicoke, a primary gas and a watery condensate.
Coal-Oil & Coal-Water Mixtures – I
1. Which of the following is not considered a type of coal according to ASTM?
a) anthracite
b) bituminous
c) peat
d) lignite
Answer: c
Explanation: 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
Answer: b
Explanation: 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
Answer: d
Explanation: 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}
Answer: d
Explanation: 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
Answer: a
Explanation: 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
Answer: d
Explanation: 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
Answer: c
Explanation: 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
Answer: c
Explanation: 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.
Coal-Oil & Coal-Water Mixtures – II
1. Presence of ______________ in dry gaseous fuel does not contribute its calorific value.
a) hydrogen
b) sulphur
c) oxygen
d) carbon
Answer: c
Explanation: Oxygen does not contribute to the calorific value of dry gaseous fuels.
2. Improper storage condition results weathering of coal and spontaneous combustion, which increases its?
a) caking index
b) yield of carbonised products
c) calorific value
d) friability and oxygen content
Answer: d
Explanation: Improper storage of coal causes loss of oxygen content, resulting in loss of heat value.
3. Laboratory gas is obtained by cracking of __________
a) fuel oil
b) gasoline
c) kerosene
d) diesel
Answer: c
Explanation: Kerosene on cracking gives laboratory gas.
4. Higher percentage of ash in coal meant for the production of metallurgical grade coke __________
a) causes brittleness in coke
b) increases abrasion resistance of coke
c) decreases hardness of coke
d) causes high toughness
Answer: b
Explanation: A high percentage of ash in coal meant for production of metallurgical grade coke causes an increase in abrasion resistance in coke.
5. Carbon content by weight in air dried wood may be about _____________ %.
a) 25
b) 50
c) 10
d) 80
Answer: b
Explanation: Air dried wood has carbon content of about 50%.
6. Softening temperature of coal is a measure of which tendency of coal?
a) clinkering tendency
b) coking tendency
c) caking tendency
d) size tendency
Answer: a
Explanation: Clinkering tendency is responsible for the softening of coal.
7. Combustion of pulverised coal as compared to lump coal __________
a) can be done with less excess air
b) develops a low temperature flame
c) develops a non-luminous flames
d) provides a lower rate of heat release
Answer: a
Explanation: Pulverisation leads to less use of air.
8. Dry air required to burn 1kg of carbon completely may be around ________________ kg.
a) 11
b) 38
c) 2
d) 20
Answer: a
Explanation: 11kg of dry air is required to burn 1kg of carbon.
9. ‘Fat coal’ means a coal having __________
a) high volatile matter
b) low ash content
c) low calorific value
d) non-smoking tendency
Answer: a
Explanation: Coal having high volatile matter is called ‘fat coal’.
10. A good quality coal should have __________
a) high ash content
b) high sulphur
c) low fusion point of ash
d) none of the mentioned
Answer: d
Explanation: A good quality coal should have high carbon content.
11. Grindability of coal is 100. It implies that __________
a) it can’t be pulverised
b) it is easily pulverised
c) can be pulverised with difficulty
d) power consumption is high in pulverisation
Answer: b
Explanation: High grindability of coal implies easy pulverisation.
Combined Cycle Power Generation MCQs
12. The difference in total carbon and fixed carbon of coal will be minimum in case of __________
a) lignite
b) bituminous coal
c) high temperature coke
d) anthracite
Answer: c
Explanation: Out of these options, high temperature coke has minimum difference.
13. Fuel gases containing hydrocarbons are not preheated before burning, because __________
a) they crack, thereby choking and fouling heat transfer surface
b) it reduces calorific value tremendously
c) it reduces flame temperature tremendously
d) there are chances of explosion during preheating
Answer: a
Explanation: Hydrocarbons crack easily, hence they are not preheated.
Synthetic Fuels, Biomass and Thermodynamic View
1. Production of producer gas from coke requires _____________ moles of nitrogen.
a) 3.76
b) 4.51
c) 2.23
d) 3.49
Answer: a
Explanation: None.
2. Which of the following mode is not used to liquefy coal?
a) hydrogenation
b) catalytic conversion
c) hydro pyrolysis
d) coal gasification
Answer: d
Explanation: In coal gasification, coal is gasified in a situ and the gas is conveyed to the surface. The other processes are methods of coal liquefaction.
3. What are the first products in Fischer-Tropsch process?
a) CO+H2
b) CO2 +H2
c) Coke + H2O
d) Coke
Answer: a
Explanation: The first products in Fischer-Tropsch process are carbon monoxide and hydrogen.
4. ____________ prohibits the use of alcohols directly in petrol engines.
a) high cost and availability
b) low octane number
c) low flash point
d) low calorific value
Answer: a
Explanation: High cost is the reason for no use of alcohols in petrol engines.
5. Which of these is not a form of bioconversion route?
a) direct combustion
b) fermentation
c) thermochemical conversion
d) biochemical conversion
Answer: b
Explanation: Fermentation is a breakdown of complex molecules in organic compounds. It is a type of biochemical conversion.
6. Which of these is a product of pyrolysis process in dry thermochemical conversion?
a) methane
b) methanol
c) ammonia
d) pyrolytic oils
Answer: d
Explanation: Pyrolytic oils, gas and char are the products of pyrolysis process.
7. Which of these is an important measure of performance in for a power plant?
a) NPHR
b) AP
c) NTO
d) HHV
Answer: a
Explanation: NPHR- net plant heat rate is the most important measure of performance for power plant. AP-auxillary power NTO-net turbine output NTHR-net turbine heat rate.
8. The overall efficiency of a power plant is given by __________
a) 3600/NTO
b) 3600/AP
c) 3600/HHV
d) 3600/NPHR
Answer: d
Explanation: The overall efficiency of a power plant is given by ɳ = 3600/NPHR.
Draught System
1. Which of these terms defines the pressure difference in the furnace?
a) draught
b) duct
c) stack
d) chimney
Answer: a
Explanation: The term ‘draught’ is used to define the static pressure in the furnace, in the various ducts and the stack.
2. The draught or pressure difference for a chimney of height of H metres is given by?
a) Δp = gH(ρa-ρg)
b) Δp = gH(ρg-ρa)
c) Δp = gHρg
d) Δp = gH(ρa+ρg)
Answer: a
Explanation: The draught produced is given by Δp = gH(ρa-ρg).
3. Which of these is not a type of mechanical draft system for a furnace?
a) balanced draft
b) induced draft
c) forced draft
d) actuated draft
Answer: d
Explanation: The three types of mechanical drafts are balanced, induced and forced drafts.
4. Stack heat losses can be minimised by __________
a) using low c.v. fuels
b) controlling the excess air
c) oxygen enrichment of combustion air
d) maintaining proper draft in the furnace
Answer: b
Explanation: Excess amount of air leads to significant losses in energy due to heat loss through flue gases.
5. Which of these accentuates clinkering trouble on furnace grate burning coal?
a) low reactivity of carbonised residue containing high proportions of iron and sulphur
b) low forced draught and low fuel bed temperature
c) thick fire bed and preheated primary air
d) all of the mentioned
Answer: d
Explanation: All these reasons lead to clinkering.
6. Natural draught produced by a chimney depends upon __________
a) density of chimney gases
b) height of chimney
c) both ‘density of chimney gases’ and ‘height of chimney’
d) none of the mentioned
Answer: c
Explanation: Natural draught depends on density of gases in chimney and its height.
7. In a furnace employing forced draught compared to induced draught __________
a) the fan operates hot and hence blades are liable to corrosion and erosion
b) positive pressure exists in the furnace
c) air is sucked in, so air leaks are more and hence furnace efficiency is reduced
d) none of the mentioned
Answer: c
Explanation: A positive pressure exists in the furnace employing forced draught.
8. Which of the following types of the fans has the highest cost?
a) centrifugal fans
b) axial fans
c) primary fans
d) gas recirculation fans
Answer: b
Explanation: Axial fans have the highest cost.
9. Which of these is not a type of drive of variable speed control?
a) variable speed turbine
b) hydraulic coupling
c) multiple speed ac motor
d) electronically adjustable turbine drive
Answer: d
Explanation: Except ‘electronically adjustable turbine drive’, all other are a type of drive in variable speed control.
Heat of Combustion-I
1. Internal energy of combustion products is ______________ than that of reactants.
a) less
b) more or less (depends on state of fuel)
c) same
d) more
Answer: a
Explanation: The internal energy of combustion is given by uRP=UP-UR which gives a negative value.
2. Higher efficiency in combustion of solid fuel cannot be achieved by ___________
a) keeping flue gas temperature very high
b) proper fuel preparation
c) supplying correct quantity of combustion air
d) adopting efficient fuel-firing technique and equipment
Answer: a
Explanation: Keeping flue gas temperature very high does not result in increased efficiency of solid fuel.
3. Bomb calorimeter is used determine the calorific value of ___________
a) solid fuels
b) liquid fuels
c) both solid and liquid fuels
d) none of the mentioned
Answer: c
Explanation: Bomb calorimeter can be used to determine the calorific value of both solid and liquid fuels.
4. Which of these is not a reason for reduction in maximum flame temperature in actuality?
a) incomplete combustion
b) heat loss to exhaust gases
c) excess air requirements
d) heat loss to surroundings
Answer: b
Explanation: Maximum flame temperature is defined on the temperature of products; hence it cannot be a reason for reduction in flame temperature.
5. Grindability index of a coal is 100. It implies that the __________
a) coal can be easily pulverised
b) coal can be pulverised with great difficulty
c) coal can’t be pulverised
d) power consumption in grinding the coal will be very high
Answer: a
Explanation: Grindability of an object is the ease with which the object can be reduced into powdered form. A measure of the same is the Grindability index of coal.
6. Tar yield in the low temperature and high temperature carbonisation of dry coal may be respectively __________ percent.
a) 10 & 3
b) 3 & 10
c) 15 & 8
d) 10 & 20
Answer: a
Explanation: Tar yield in the low temperature and high temperature carbonisation of dry coal may be respectively 10 & 3 percent.
7. High amount of sulphur and phosphorous in coke causes __________
a) decrease in its calorific value
b) increase in its strength
c) brittleness of steel made by using it
d) none of the mentioned
Answer: d
Explanation: None of the effects are caused by the increased strength of sulphur & phosphorus in coke.
8. The difference between the enthalpy of products & the enthalpy of reactants when complete combustion occurs at specific temperature & pressure is called?
a) Enthalpy of burning
b) Enthalpy of Combustion
c) Enthalpy of complete combustion
d) None of the mentioned
Answer: b
Explanation: Enthalpy of Combustion is defined as, “The difference between the enthalpy of products & the enthalpy of reactants when complete combustion occurs at specific temperature & pressure”.
9. The internal energy of products minus the internal energy of reactants for complete combustion at specific temperature & pressure gives the internal energy of?
a) combustion
b) partial combustion
c) complete combustion
d) none of the mentioned
Answer: a
Explanation: The internal energy of products minus the internal energy of reactants is called the internal energy of combustion.
10. HCV stands for?
a) Higher Combustion Value
b) Higher Convection Value
c) Higher Calorific Value
d) Higher Calorific Value
Answer: d
Explanation: HCV is an acronym for High Calorific Value.
Heat of Combustion – II
1. The heat transferred when the H2O in the products is in the liquid state is called?
a) HCV
b) LCV
c) LHV
d) None of the mentioned
Answer: a
Explanation: The heat transferred when the H2O in the products is in the liquid state is called HCV [Higher Calorific Value].
2. The heat transferred when the H2O in the products is in the vapour state is called?
a) HCV
b) LCV
c) HHV
d) None of the mentioned
Answer: b
Explanation: The heat transferred when the H2O in the products is in the vapour state is called LCV [Lower Calorific Value].
3. The maximum temperature achieved for given reactants is called?
a) Practical Flame Temperature
b) Critical Temperature
c) Theoretical Flame Temperature
d) None of the mentioned
Answer: c
Explanation: Theoretical Flame Temperature is the maximum temperature achieved for given reactants.
4. Maximum Theoretical Flame Temperature corresponds to _____________
a) Partial Combustion
b) Incomplete Combustion
c) Complete combustion
d) None of the mentioned
Answer: c
Explanation: Maximum Theoretical Flame Temperature corresponds to Complete Combustion.
5. In pure oxygen, the maximum flame temperature is _____________
a) higher than the theoretical flame temperature
b) lower than the theoretical flame temperature
c) equal to the theoretical flame temperature
d) none of the mentioned
Answer: a
Explanation: In pure oxygen, the maximum flame temperature is higher than the theoretical flame temperature because of dilution effect of Nitrogen.
6. Maximum permissible temperature in a gas turbine is?
a) Fixed
b) Variable
c) Linearly increasing
d) Linearly decreasing
Answer: a
Explanation: Maximum permissible temperature in a gas turbine is Fixed from metallurgical considerations.
7. Dissociation is directly proportional to temperature.
a) True
b) False
Answer: a
Explanation: Dissociation is directly proportional to temperature as when the temperature increases, the amount of dissociation also increases & vice-versa.
8. Spontaneity of a chemical reaction depends on?
a) Enthalpy of reaction
b) Energy of reaction
c) Gibbs Free Energy
d) None of the mentioned
Answer: c
Explanation: Gibbs free energy is the parameter which determines the spontaneity of the reaction after determining its randomness.
9. For exothermic reactions, free energy change is?
a) positive
b) negative
c) zero
d) none of the mentioned
Answer: b
Explanation: Gibbs free energy is the parameter which determines the spontaneity of the reaction after determining its randomness. For exothermic reactions, this energy difference has to be negative.
Heat of Combustion-III
1. The free energy of chemical elements at 1 atm & 25HoC is assumed to be?
a) Negative
b) Positive
c) Zero
d) None of the mentioned
Answer: c
Explanation: Initially, for a certain time. the change in the values of free energy change remains same and equal to zero.
2. Effect of dissociation is lower for lean mixtures.
a) True
b) False
Answer: a
Explanation: Effect of dissociation is directly proportional to the amount of oxygen present in the reaction.
3. The maximum turbine flame temperature can be can be controlled by?
a) amount of oxygen extracted
b) amount of air supplied
c) amount of air extracted
d) none of the mentioned
Answer: b
Explanation: Turbine maximum flame temperature is controlled entirely by the amount of air supplied.
4. If the enthalpy change for a reaction is zero, ΔG° is equal to _____________
a) TΔS°
b) -TΔS°
c) -ΔH°
d) lnKeq
Answer: b
Explanation: Gibbs free energy is the parameter which determines the spontaneity of the reaction after determining its randomness.
5. Flue gas discharge velocity through chimney of a big thermal power plant may be around __________ m/sec.
a) 0.5
b) 500
c) 10
d) 50
Answer: c
Explanation: Flue gas discharge velocity through chimney of a big thermal power plant may be around 10 m/sec.
6. Calorific value of coal middling generated in coal washeries during washing of coal may be around __________ Kcal/kg.
a) 1000
b) 4000
c) 6000
d) 8000
Answer: b
Explanation: Calorific value of coal middling generated in coal washeries during washing of coal may be around 4000 Kcal/kg.
7. Combustion of pulverised coal as compared to that of lump coal _____________
a) develops a non-luminous flame
b) can be done with less excess air
c) develops a low temperature flame
d) provides a lower rate of heat release
Answer: b
Explanation: The amount of air required for combustion of pulverised coal is less in comparison to the amount of air in the combustion of Lump Coal.
8. For endothermic reactions, Gibbs free energy change has to be?
a) negative
b) positive
c) zero
d) none of the mentioned
Answer: b
Explanation: Gibbs free energy is the parameter which determines the spontaneity of the reaction after determining its randomness. For endothermic reactions, this energy difference has to be positive.