Essential Steam Boilers Objective Questions For Gate Exam
1.The equivalent evaporation of a boiler is a measure to compare
the given boiler with the model
the two different boilers of the same make
two different makes of boilers operating under the same operating conditions
two boilers of same make but operaing under different conditions
any type of boilers operating under any conditions.
ANSWER : : any type of boilers operating under any conditions.
2.Coke is produced by
pulverising coal in inert atmosphere
heating wood in a limited supply of air at temperatures below 300GC
strongly heating coal continuously for about 48 hours in the absence of air in a closed vessel
binding the pulverised coal into bricketts
enriching carbon in the coal.
ANSWER : : strongly heating coal continuously for about 48 hours in the absence of air in a closed vessel
3.Stoichiometric quantity of air is the
air present in atmosphere at NTP conditions
air required for complete combustion of fuel with no excess air
air required for optimum combustion so as to have reasonable excess air
air required to convert CO into C02
air required to form an explosive mixture.
ANSWER : : air required for complete combustion of fuel with no excess air
4.Equivalent evaporation is the amount of water evaporated in a boiler from and at
0�C
100�C
saturation temperature at given pres�sure
room temperature
20�C.
ANSWER : : 100�C
5.Heating of dry steam above saturation temperature is known as
enthalpy
superheating
supersaturation
latent heat
super tempering.
ANSWER : : superheating
6.Superheating of steam is done at
constant volume
constant temperature
constant pressure
constant entropy
constant enthaply.
ANSWER : : constant pressure
7.The saturation temperature of steam with increase in pressure increases
linearly
rapidly first and then slowly
slowly first and then rapidly
inversely
none of the above.
ANSWER : : rapidly first and then slowly
8.1 kg.m is equal to
9.81 Joules
All Joules
427 Joules
102 Joules
539 Joules.
ANSWER : : 9.81 Joules
9.At very low temperature, the melting and boiling temperatures become equal. This temperature is
373�K
273.16�K
303�K
0�K.
300�K.
ANSWER : : 273.16�K
10.On Millier chart, the constant pressure lines
diverge from left to right
diverge from right to left
are equally spaced throughout
first rise up and then fall
none of the above.
ANSWER : : diverge from left to right
11.If a steam sample is nearly in dry condition, then its dryness fraction can be most accurately determined by
throttling calorimeter
separating calorimeter
combined separating and throttling calorimeter
bucket calorimeter
none of the above.
ANSWER : : throttling calorimeter
12.One kg of steam sample contains 0.8 kg dry steam; it’s dryness fraction is
0.2
0.8
1.0
0.6
0.5.
ANSWER : : 0.8
13.A wet vapour can be completely specified by
pressure only
temperature only
dryness fraction only
specific volume only
pressure and dryness fraction.
ANSWER : : pressure and dryness fraction.
14.If xx and x2 be the dryess fractions obtained in separating calorimeter and throttling calorimeter respectively, then the actual dryness fraction of steam will be
xxx2
x, + x2
xxx2
The specific heat of superheated steam in kcal/kg is generally of the order of
opt 5
ANSWER : 1 0.1
15.Sublimation region is the region where
solid and vapour phases are in equilibrium
solid and liquid phases are in equilibrium
liquid and vapour phases are in equilibrium
solid, liquid and vapour phases are in equilibrium
none of the above.
ANSWER : : solid and vapour phases are in equilibrium
16.Carbonisation of coal is the process of
pulverising coal in inert atmosphere
heating wood in a limited supply of air at temperatures below 300�C
strongly heating coal continuously for about 48 hours in the absence of air in a closed vessel
binding the pulverised coal into brickettes
enriching carbon in the coal.
ANSWER : : strongly heating coal continuously for about 48 hours in the absence of air in a closed vessel
17.On Mollier chart, flow through turbine is represented by ‘
horizontal straight line
vertical straight line
straight inclined line
curved line
none of the above.
ANSWER : : vertical straight line
18.The specific volume of steam with increase in pressure decreases
linearly
slowly first and then rapidly
rapidly first and then slowly
inversely
none of the above.
ANSWER : : rapidly first and then slowly
19.On Mollier chart, free expansion, or throttling process from high pressure to atmosphere is represented by
horizontal straight line
vertical straight line
straight inclined line
curved line
none of the above.
ANSWER : : horizontal straight line
20.The coal requirement per kW hour generation in the thermal power plant is of the order of
0.1 to 0.2 kg
0.2 to 0.4 kg
0.6 to 0.8 kg
1.0 to 1.5 kg
1.5 to 2 kg.
ANSWER : : 0.6 to 0.8 kg
21.The latent heat of steam at pressures greater than atmospheric in comparison to latent heat at atmospheric pressure is
less
more
equal
may be less or more depending on temperature
unpredictable.
ANSWER : : less
22.The critical pressure at which latent heat of vaporization is zero is
225.65 kgf/cm2
273 kgf/cm2
100 kgf/cm2
1 kgf/cm2
– 1 kgf/cm2.
ANSWER : : 225.65 kgf/cm2
23.If partial pressure of air and steam be pa and ps respectively in a condenser, then according to Dalton’s law, the pressure in condenser is equal to
Ps-Pa
pa-ps
Pa+P,
ps+pa
none
ANSWER : : Pa+P,
24.At which pressure the properties of water and steam become identical
0.1 kg/cm2
1 kg/cm2
100 kg/cm2
225.6 kg/cm2
it is never possible.
ANSWER : : 225.6 kg/cm2
25.The latent heat of steam with increase of pressure
remains same
increases
decreases
behaves unpredictably
none of the above.
ANSWER : : decreases
26.The dry saturated steam at very high pressure (150-200 kg/cm2) when throttled to atmosphere will become
wet
superheated
remain dry saturated
dry
none of the above.
ANSWER : : wet
27.Equivalent evaporation of water is the evaporation “for a feed water supply at 100�C
and its corresponding conversion into dry saturated steam at 100�C and 1.033 kg/cm2
and its corresponding conversion into dry steam at desired boiler pressure
conversion into steam at atmospheric condition
conversion into steam at the same pres-sure at which feed water is supplied
none of the above.
ANSWER : : and its corresponding conversion into dry saturated steam at 100�C and 1.033 kg/cm2
28.Water at pressure of 4 kg/cm2 and 160�C temperature when exposed to atmosphere will
boil
flash i.e. get converted into steam
remain as it was
cool down
none of the above.
ANSWER : : flash i.e. get converted into steam
29.In an experiment to determine dryness fraction of steam, the mass of water separated was 1.2 kg in 15 mts and the mass of steam passed out in same time was 4.8 kg. Dryness fraction is
40%
25%
50%
80%
90%.
ANSWER : : 80%
30.Hygrometery deals with the
Hygroscopic substances
water vapour in air
temperature of air
pressure of air
density measurement.
ANSWER : : water vapour in air
31.Latent heat of dry steam at atmospneric pressure is equal to
539 kcal/kg
539 BTU/lb
427 kcal/kg
100 kcal/kg
471 kcal/kg.
ANSWER : : 539 kcal/kg
32.While steam expands in turbines, theoretically the entropy
remains constant
increases
decreases
behaves unpredictably
none of the above.
ANSWER : : remains constant
33.The pressure at which latent heat of vaporisation of water is zero, is below atmospheric pressure
1 kg/cm2
100 kg/cm2
170 kg/cm2
225.6 kg/cm2.
ANSWER : : 225.6 kg/cm2.
34.At critical point, i.e. p=225.65 kg/cm2, the latent enthalpy of vaporization is
maximum
minimum
zero
depends on temperature also
none of the above.
ANSWER : : zero
35.The dry saturated steam at very low pressure, (5-10 kg/cm2) when throttled to atmosphere will become
wet
superheated
remain dry saturated
dry
none of the above.
ANSWER : : superheated
36.Heating wet steam at constant temperature is heating it at constant
volume
pressure
entropy
enthalpy
none of the above.
ANSWER : : pressure
37.Mechanical equivalent of heat for 1 kcal or Joule’s equivalent is equal to
421 kgm
421 kgm
539 kgm
102 kgm
75 kgm.
ANSWER : : 421 kgm
38.Adiabatic process is
essentially an isentropic process
non-heat transfer process
reversible process
constant temperature process
constant enthalpy process.
ANSWER : : non-heat transfer process
39.The evaporation of 15.653 kg of water per hour from and at 100�C is called
evaporative capacity
factor of evaporation
equivalent evaporation
one boiler h.p.
boiler efficiency.
ANSWER : : one boiler h.p.
40.Orsat meter is used for
gravimetric analysis of the flue gases
volumetric analysis of the flue gases
mass flow of the flue gases
measuring smoke density of flue gases
none of the above.
ANSWER : : volumetric analysis of the flue gases
41.During polytropic process
heat transfer takes place across cylinder walls
work is done
steam may be wet, dry or superheated after expansion
all of the above
none of the above.
ANSWER : : all of the above
42.Pick up the wrong statement about critical condition of steam
latent heat is zero
liquid directly becomes steam
specific volume of steam and liquid is same
this is the maximum pressure limit
all properties of liquid and steam are same.
ANSWER : : this is the maximum pressure limit
43.The state of vapour under saturation condition is described by
pressure alone
temperature alone
pressure and temperature
pressure and dryness fraction
dryness fraction alone.
ANSWER : : pressure and dryness fraction
44.Water boils when its vapour pressure
equals that of the surroundings
equals 760 mm of mercury
equals to atmospheric pressure
equals the pressure of water in the con-tainer
boiling has ^nothing to do with vapour pressure.
ANSWER : : equals that of the surroundings
45.In a throttling process
heat transfer takes place
work is done by the expanding steam
internal energy of steam changes
all of the above
none of the above.
ANSWER : : none of the above.
46.The increase in pressure
lowers the boiling point of a liquid
raises the boiling point of a liquid
.does not affect the boiling point of a liquid
reduces its volume
none of the above.
ANSWER : : raises the boiling point of a liquid
47.In a throttling process
steam temperature remaisn constant
steam pressure remains constant
steam enthalpy remains constant
steam entropy remains constant
steam volume remains constant.
ANSWER : : steam enthalpy remains constant
48.Efficiency of a thermal cycle increases by
regeneration
reheating of steam
both (a) and (b)
cooling of steam
none of the above.
ANSWER : s: c
49.Efficiency of rankine cycle can be increased by
decreasing initial steam pressure and temperature
increasing exhaust pressure
decreasing exhaust pressure
increasing the expansion ratio
increasing number of regenerative heaters.
ANSWER : : decreasing initial steam pressure and temperature
50.Cochran boiler is a
horizontal fire-tube boiler
horizontal water-tube boiler
veritcal water-tube boiler
vertical fire tube boiler
forced circulating boiler.
ANSWER : : vertical fire tube boiler
51.The change in internal energy in steam engines equals to
work done during the rankine cycle ;
work done during compression.
work done during adiabatic expansion
change in enthalpy
none of the above.
ANSWER : : work done during the rankine cycle ;
52.Which of the following gases has the highest calorific value
producer gas
coal gas.
water gas
blast furnace gas
coke oven gas.
ANSWER : : coal gas.
53.The biggest size of thermal power unit operating in India is
30 MW
60 MW
100 MW
210 MW
500 MW.
ANSWER : : 500 MW.
54.Steam engine operates on
carnot cycle
joule cycle
Stirling cycle
brayton cycle
none of the above.
ANSWER : : brayton cycle
55.A packaged boiler is one in which various parts like firing equipment, fans, feed pumps and automatic controls are
supplied by same manufacturer loose and assembled at site
supplied mounted on a single base
purchased from several parties and packed together at site
packaged boiler does not exist
none of the above.
ANSWER : : supplied mounted on a single base
56.Which of the following is a fire tube boiler
locomotive boiler
Babcock and Wilcox boiler
Stirling boiler.
all of the above
none of the above.
ANSWER : : locomotive boiler
57.The length of Cornish boiler is of the order of
2-4 m
3-5 m
5-7.5 m
7-9 m
9-11 m.
ANSWER : : 5-7.5 m
58.Which of the following substance will have same percentage in both proximate and ultimate analysis
ash
volatile matter
moisture
hydrogen
none of the above.
ANSWER : : ash
59.100% efficiency of a thermal cycle cannot be achieved because of
frictional losses
it is not possible to achieve 0�K temperature
leakage
non-availability of ideal substance
none of the above.
ANSWER : : it is not possible to achieve 0�K temperature
60.Fire tube boilers are those in which
flue gases pass through tubes and water around it
water passes through the tubes and flue gases around it
forced circulation takes place
tubes are laid vertically
none of the above.
ANSWER : : flue gases pass through tubes and water around it
61.Lancashire boiler is of
stationary
horizontal type
natural circulation type
internally fired type
all of the above.
ANSWER : : all of the above.
62.An ideal regenerative cycle is
equal to carnot cycle
less than carnot cycle
more than carnot cycle
could be anything
none of the above.
ANSWER : : less than carnot cycle
63.The number of flue tubes in Lancashire boiler is
zero
one
two
four
many.
ANSWER : : two
64.Water tube boilers are those in which
flue gases pass through tubes and water around it
water passes through the tubes and flue gases around it
work is done during adiabatic expansion
change in enthalpy
none of the above.
ANSWER : : work is done during adiabatic expansion
65.The diameter of fire tube of Cornish boiler compared to its shell is
one half
one third
one-fifth
two-fifth
three-fifth.
ANSWER : : one half
66.The diameter of cylindrical shell of the Lancashire boiler is of the order of
1 tp 1.25m
1 to 1.75 m
2 to 4 m
1.75 to 2.75 m
2.25 to 4.5 m.
ANSWER : : 1.75 to 2.75 m
67.For burning 1 kg of carbon to CO as per chemically correct combustion, amount of air required is
1 kg
4/3kg
8/3kg
2 kg
16/3 kg.
ANSWER : : 4/3kg
68.The diameter of Cornish boiler is of the order of
1-2 m
1.5-2.5 m
2-3 m
2.5-3.5 m
0.5 to 1 m.
ANSWER : : 1-2 m
69.Lancashire ‘boiler is a
stationary fire tube boiler
stationary water tube boiler
water tube boiler with natural/forced circulation
mobile fire tube boiler
none of the above.
ANSWER : : stationary fire tube boiler
70.Which of the following is a water tube boiler
locomotive boiler
Cochran boiler
Cornish boiler
Babcock and Wilcox boiler
Lancashire boiler.
ANSWER : : Babcock and Wilcox boiler
71.Locomotive type’ boiler is
horizontal multitubular water tube boiler
water wall enclosed furnace type
vertical tubular fire tube type
horizontal multi-tubular fire tube type
none of the above types.
ANSWER : : horizontal multi-tubular fire tube type
72.One kilowatt-hour energy is equivalent to
1000 J
360 kJ
3600 kJ
3600 kW/sec
1000 kJ.
ANSWER : : 3600 kJ
73.The crown of the fire box is made hemispherical in order to
give maximum space
give maximum strength
withstand pressure inside boiler ,
resist intense heat in fire box
enable easy,manufacture.
ANSWER : : resist intense heat in fire box
74.The diameters of fire tubes and superheaer tubes in locomotive boiler are
47.5 mm, 130 mm
32.5 mm, 180 mm
65.5 mm, 210 mm
24.5 mm, 65 mm
opt 5
ANSWER : : 47.5 mm, 130 mm
75.In locomotive boiler, maximum steam pressure is limited to
1 kg/cm2
5 kg/cm2
10 kg/cm2
18 kg/cm2
31 kg/cm2.
ANSWER : : 18 kg/cm2
76Hard coke is produced by carborisation of coal a atmospheric temperature
500-600�C
70O-850�C
95O-1100�C
120O-1500�C.
ANSWER : : 95O-1100�C
76.The water tubes in a babcock and wilcox boiler are
horizontal
vertical
inclined
horizontal and inclined
vertical and inclined.
ANSWER : : inclined
77.The shell diameter and length of locomotive boiler are
1.5 m, 4 m
1.5 m, 6 m
1 m, 4 m
2 m, 4 m
1.5 m, 8 m.
ANSWER : : 1.5 m, 4 m
78.Pick up the correct statement as regards Cornish boiler and Lancashire boiler
cornish is fire tube and lancashire is water tube
cornish is water tube and lancashire is fire tube
cornish has two fire tubes and lancashire has one
lancashire has two fire tubes and cornish has one
both have two fire tubes.
ANSWER : : lancashire has two fire tubes and cornish has one
79.Locomotive boiler is of the following type
multitubular
horizontal
internally fired
mobile
all of the above.
ANSWER : : all of the above.
80.The fire tubes in, a Coarran and Scotish marine boiler are
horizontal
vertical
inclined
both horizontal and vertical
horizontal and inclined.
ANSWER : : horizontal
81.In accelerated circulation type boiler
heating takes place at bottom and the water supplied at bottom gets converted into the mixture of stdam bub bles and hot water which rise to durm
water is supplied in drum and through down comers” located in atmospheric condition it passes to the water wall and rises to drum in the from of mixture of water and steam
feed pump is employed to supplement natural circulation in water wall type furnace
water is converted into steam in one pass without any recirculation
water is fed under high pressure and high velocity.
ANSWER : : water is supplied in drum and through down comers” located in atmospheric condition it passes to the water wall and rises to drum in the from of mixture of water and steam
82.The basic purpose of drum in boiler is to
serve as storage of steam
serve as storage of feed water for water wall
remove salts from water
separate steam from water
control level.
ANSWER : : separate steam from water
83.Which of the following is steam dbal
non-coking bituminous coal
brown coal
pulverised coal
coking bituminous coal
none of the above.
ANSWER : : non-coking bituminous coal
84.Which of the following boilers is best suited to meet fluctuating demands
babcock and wilcox
locomotive
lancashire
cochran
comish.
ANSWER : : locomotive
85.The function of injector used in small steam plants is to
create vacuum in furnace
create vacuum at turbine exhaust
pump feed water
dose chemicals in feed water
control steam temperature by injecting water.
ANSWER : : pump feed water
86.The diameter of internal flue tubes in a Lancashire boiler compared to its shell is
one-half
one-third
one-fourth
one-fifth
two-fifth.
ANSWER : : two-fifth.
87.Duplex feed pumps are used in small steam boilers. These operate on the principle of
centrifugal pump
axial flow pump
gear pump
ejector pump
reciprocating pump.
ANSWER : : reciprocating pump.
88.The diameter of tubes for natural circulation boiler as compared to controlled circulation boilers is
more
less
same
could be more or less depending on other factors
none of the above.
ANSWER : : more
89.The high pressure boiler is oiie producing steam at a pressure more than atmospheric pressure
5 kg/cm2
10 kg/cm2
40 kg/cm2
75-80 kg/cm2.
ANSWER : : 75-80 kg/cm2.
90.In natural circulation type boiler,
heating takes place at bottom and the water supplied at bottom gets converted into the mixture of steam bubbles and hot water which rise to drum
water is supplied in durm and through down-comers located in atmospheric conditon it passes to the water wall and rises to drum in the form of mixture of water and steam
feed pump is employed to supplement natural circulation in water wall type furnace
water is converted into steam in one . pass without any recirculation
water is fed at atmospheric pressure.
ANSWER : : heating takes place at bottom and the water supplied at bottom gets converted into the mixture of steam bubbles and hot water which rise to drum
91.The best suited coal for chain or travelling grate stoker boiler is
coking coal
non coking or free burning coal
pulverised coal
high sulphur coal
least ash content coal.
ANSWER : : non coking or free burning coal
92.Which of the following varieties of coals is mostly used in steam boilers
non-coking bituminous coal
brown coal
peat
coking bituminous coal
none of the above.
ANSWER : : none of the above.
93.A boiler in India should conform to safety regulations of
DIN
BS
ASTM
IBR
GOST.
ANSWER : : IBR
94.. Hard coke is used in
cement industry
thermal power plant
blast furnace
domestic use
locomotives
ANSWER : : blast furnace
95.The difference between Cornish boiler and Lancashire boiler is that
former is fire tube type and latter is water tube type boiler
former is water tube type and latter is fire tube type
former contains one fire tube and latter contains two fire tubes
none/of the above.
opt 5
ANSWER : : former contains one fire tube and latter contains two fire tubes