Fuels and Combustion MCQs : This section focuses on the "Fuels and Combustion". These Multiple Choice Questions (MCQs) should be practiced to improve the Fuels and Combustion skills required for various interviews (campus interview, walk-in interview, company interview), placement, entrance exam and other competitive examinations.
Question 1
A coal containing very high percentage of durain is called __________ coal.
A. bright
B. splint
C. non-banded
D. boghead
Question 2
A coal having high amount of volatile matter
A. would require smaller combustion chamber.
B. produces very little of tar and gas on carbonisation.
C. ignites easily and burns with long smoky flame.
D. all (a), (b) and (c).
Question 3
A coal with high ash content is undesirable, as
A. it is abrasive to the coal pulveriser (ie.g. ball mill) and the combustion chamber.
B. the ash in molten condition gets absorbed in the pores of the refractory lining of the furnace and causes its spalling due to different co-efficient of expansion/contraction of the refractory and the ash.
C. the ash retains the sulphur & phosphorus and thus affects the quality of products in metallurgical furnace apart from increasing the slag volume. Besides, it may fuse and stick to the boiler tubes thereby reducing the heat transfer.
D. all (a), (b) and (c).
Question 4
Actual flame temperature is always lower than the adiabatic flame temperature, because there is
A. no possibility of obtaining complete combustion at high temperature.
B. always loss of heat from the flame.
C. both (a) and (b).
D. neither (a) nor (b).
Question 5
Adiabatic flame temperature of a fuel is dependent on the initial temperature of
A. fuel
B. air
C. both (a) & (b)
D. neither (a) nor (b)
Question 6
Bituminous coal
A. ignites less easily than anthracite.
B. is generally coking.
C. burns with smoky yellow flame.
D. both (b) and (c).
Question 7
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
Question 8
Carbon Content by weight in air dried wood may be about __________ percent.
A. 10
B. 25
C. 50
D. 80
Question 9
Coke oven gas consists mainly of
A. H2, & CH4
B. CO, & CO2
C. H2, & CO
D. CH4, & CO
Question 10
Combustion of pulverised coal as compared to that of lump coal
A. develops a non-luminous flame.
B. develops a low temperature flame.
C. can be done with less excess air.
D. provides a lower rate of heat release.
Question 11
Combustion reaction of fuels is a/an __________ reaction.
A. auto catalytic
B. exothermic
C. endothermic
D. none of these
Question 12
During combustion of gaseous fuels, deficiency of air
A. lengthens the flame.
B. tends to shorten the flame.
C. does not affect the flame length.
D. increases the flame temperature.
Question 13
Explosion limit of blast furnace gas is 37 to 71% gas in gas-air mixture. It means that the blast furnace gas will explode when burnt in a confined space, if its concentration in the gas-air mixture is __________ percent.
A. < 37%
B. >71%
C. in between 37 & 71%
D. none of these
Question 14
Flue gas discharge velocity through chimney of a big thermal power plant may be around __________ m/sec.
A. 0.5
B. 10
C. 50
D. 500
Question 15
Fuel gases containing hydrocarbons (ie.g. coke oven gas) are not preheated before burning, mainly because
A. the hydrocarbons crack thereby choking and fouling the heat transfer surface by carbon soot.
B. it reduces its calorific value tremendously.
C. it reduces its flame temperature tremendously.
D. there are chances of explosion during preheating.
Question 16
Gray King Assay and Swelling Index of a coal is a measure of its
A. swelling characteristics.
B. abradability.
C. agglutinating properties.
D. resistance to impact breakage.
Question 17
Gross & net calorific value is the same for
A. blast furnace gas
B. coke oven gas
C. L.D. converter gas
D. none of these
Question 18
Gross and net calorific value of a fuel will be the same
A. if its ash content is zero.
B. ifits carbon content is very low.
C. if its hydrogen/hydrogen compound content is zero.
D. under no circumstances.
Question 19
High temperature in gasification of coal favours
A. high production of CO2.
B. low production of CO2.
C. high production of CO.
D. both (b) and (c).
Question 20
Higher efficiency in the combustion of solid fuel can not be achieved by
A. proper fuel preparation.
B. keeping the flue gas exhaust temperature very high.
C. adopting efficient-fuel firing technique & equipment.
D. supplying correct quantity of combustion air.
Question 21
Higher percentage of ash in coal meant for the production of metallurgical grade coke
A. decreases the hardness of coke.
B. decreases the abrasion resistance of coke.
C. causes brittleness in steel.
D. none of these.
Question 22
Improper storage condition results in the weathering of coal and spontaneous combustion, which increases its
A. caking index.
B. yield of carbonised products.
C. friability & oxygen content.
D. calorific value.
Question 23
In high temperature carbonisation of coal compared to low temperature carbonisation
A. yield of ammonia is less.
B. aromatic content of tar is low.
C. H2 content in the coke oven gas is more.
D. calorific value of the coke oven gas is lower.
Question 24
Junker's calorimeter is used to determine the calorific value of
A. pulverised coal
B. gaseous fuels
C. fuel oil
D. none of these
Question 25
Laboratory gas is obtained by the cracking of
A. gasoline
B. diesel
C. fuel oil
D. kerosene
Question 26
Low temperature carbonisation
A. is mainly for producing the smokeless domestic coke.
B. is meant for the production of 'metallurgical coke'.
C. produces higher quantity of gas than high temperature carbonisation.
D. produces less quantity of tar than high temperature carbonisation.
Question 27
Natural draught produced by a chimney depends upon the
A. density of the chimney gases.
B. height of the chimney.
C. both (a) and (b).
D. neither (a) nor (b).
Question 28
Pensky-Marten apparatus is used for those oils, whose flash points are __________ °F.
A. <120
B. >120
C. <90
D. 90-110
Question 29
Pick out the wrong statement.
A. LPG is also used as fuel for automobiles & small furnaces and for cutting & welding of metals.
B. The minimum temperature, at which a petroleum oil vapor catches fire and continues to burn, is called its flash point.
C. Each ton of petroleum oil on distillation produces about 30-50 Nm3 of gas.
D. Maximum yield of naphthalene is obtained on distillation of crude oil.
Question 30
Presence of __________ in a dry gaseous fuel does not contribute to its calorific value.
A. sulphur
B. oxygen
C. hydrogen
D. carbon
Question 31
Presence of free moisture in coal during its high temperature carbonisation
A. reduces the coking time.
B. protects the volatile products from pyrolysis (cracking) in the presence of hot coke and hot oven walls.
C. increases the loss of fine coal dust from the ovens when charging.
D. none of these.
Question 32
Prime coking coal is always blended with medium or non- coking coal before ear-bonisation
A. to check against its excessive swelling during heating, which may exert high pressure and damage coke oven walls.
B. because, it alone produces unreactive coke.
C. both (a) and (b).
D. neither (a) nor (b).
Question 33
Ratio of primary air to secondary air increases with increase in the rank of coal, because the
A. high rank coals have higher amount of volatile matter.
B. ratio of fixed carbon to volatile matter increases.
C. oxygen content progressively decreases.
D. calorific value of the coal increases.
Question 34
Size of blast furnace grade coke is __________ mm.
A. 25-80
B. 0-15
C. 15-25
D. >100
Question 35
Stack heat losses can be minimised by
A. controlling the excess air.
B. oxygen enrichment of combustion air.
C. using low c.v. fuels.
D. maintaining proper draft in the furnace.
Question 36
Temperature of preheated air used for the transportation of pulverised coal through pipes to the burner of a boiler furnace is restricted to a maximum limit of about 300° C to avoid the
A. requirement of large volume combustion chamber.
B. risk of explosion.
C. chances of clinker formation.
D. incomplete combustion of coal.
Question 37
The gas which contributes maximum to the heating value of natural gas is
A. CO
B. CO2
C. H2
D. CH4
Question 38
The temperature at which plastic layer formation takes place during carbonisation of coal varies from __________ °C.
A. 100 to 150
B. 350 to 450
C. 550 to 650
D. 700 to 850
Question 39
When incomplete combustion loss is high, the flue gas analysis shows large amount of
A. CO2
B. CO
C. O2
D. C
Question 40
Which of the following accentuates clinker-ing trouble on furnace grate burning coal ?
A. Low reactivity of carbonised residue containing high proportions of iron & sulphur.
B. Low forced draught and fuel bed temperature.
C. Thick fire bed and preheated primary air.
D. All (a), (b) and (c).
Question 41
Which of the following constituents of coal is the most important in the production of coke?
A. Moisture
B. Ash
C. Volatiles
D. Carbon
Question 42
Which of the following gaseous fuels has the lowest calorific value ?
A. Gobar gas
B. Refinery gas
C. Converter gas
D. Blast furnace gas
Question 43
Which of the following is not a by-product recovered in a high temperature coal carbonisation plant ?
A. Benzol
B. Pitch-cresosote mixture (PCM)
C. Napthalene
D. Ethylene
Question 44
Which of the following is not a product of tar distillation ?
A. Phenol & naphthalene
B. Benzol & pitch
C. Anthracene & creosote
D. None of these
Question 45
Which of the following is not used as a binder in coal briquetting ?
A. Tar
B. Molasses
C. Pitch
D. Line
Question 46
Which of the following is the most reactive (as regards the formation of CO + H2 from C + H2O) ?
A. Blast furnace coke
B. Low temperature coke
C. Anthracite coal
D. Sub-bituminous coal
Question 47
Which of the following is used for making the explosive 'TNT' ?
A. Benzol
B. Toluene
C. Pyridine
D. Cerosote
Question 48
'Wobbe index' is a characteristic of
A. solid fuels
B. gaseous fuels
C. liquid fuels
D. fat coals
Question 49
Yield of coke oven gas in low temperature carbonisation of coal is about __________ Nm3 /ton of dry coal.
A. 60
B. 160
C. 500
D. 750
Question 50
Which of the following is not a by-product fuel?
A. Producer gas
B. Blast furnace gas
C. Coke oven gas
D. Refinery gas
Question 51
Which of the following is not a by-product fuel?
A. Sewage gas
B. Refinery gas
C. Producer gas
D. Bagasse
Question 52
Volatile matter content in coking coal may be about __________ percent.
A. 1
B. 7
C. 22
D. 46
Question 53
Dry air required to burn 1 kg of carbon completely may be around __________ kg.
A. 11
B. 2
C. 20
D. 38
Question 54
Gobar gas is produced by the __________ of cown dung.
A. Fermentation
B. Oxidation
C. Hydrogenation
D. None of these
Question 55
Efficiency of the combustion of a fuel is judged by the __________ the flue gas.
A. %of CO₂ in
B. % of O₂in
C. Temperature of
D. Colour of
Question 56
Anthracite can be used for
A. Recarbonising steel
B. Making carbon electrodes
C. Blending with highly coking coal to check its swelling which helps in saving coke even walls from damage and to produce high strength coke
D. All of the above
Question 57
Anthracite coal
A. Contains more volatile matter than bituminous coal
B. Ignites more easily than bituminous coal
C. Is essentially a coking coal
D. Burns with short, bluish, yellow-tipped flame producing very little smoke
Question 58
Ignition temperature decreases progressively from anthracite to lignite, because
A. Volatile matter content increases
B. Carbon content decreases
C. Moisture content increases
D. Ash content increases
Question 59
Blast furnace gas is a very poisonous gas because of its predominantly high __________ content.
A. H₂O
B. CO₂
C. CO
D. CH₄
Question 60
The maximum adiabatic flame temperature in air as compared to that in pure oxygen is
A. Much lower
B. Much higher
C. Same
D. Either lower or higher, depends on the type of fuel
Question 61
Coke made in narrower by-product coke ovens (as compared to wider ovens) is
A. Less reactive
B. Stronger
C. Smaller in size
D. All of the above
Question 62
Ammonia content in raw coke oven gas is about __________ gm/Nm³.
A. 1
B. 15
C. 50
D. 100
Question 63
Fusion point of coal ash increases with increase in its __________ content.
A. Iron sulphate
B. Iron silicate
C. Lime and magnesia
D. All of the above
Question 64
A coal with high ash content is undesirable, as
A. It is abrasive to the coal pulveriser (ie.g. ball mill) and the combustion chamber
B. The ash in molten condition gets absorbed in the pores of the refractory lining of the furnace and causes its spalling due to different co-efficient of expansion/contraction of the refractory and the
C. The ash retains the sulphur & phosphorus and thus affects the quality of products in metallurgical furnace apart from increasing the slag volume. Besides, it may fuse and stick to the boiler tubes
D. All of the above
Question 65
Fuel for a fast breeder nuclear reactor is
A. Plutonium
B. Uranium
C. Radium
D. Neptunium
Question 66
Water gas constitutes mainly of
A. CO & H₂
B. CO & N₂
C. CO₂ & H₂
D. CH₄ & H₂
Question 67
If the specific heat of gaseous products of combustion of a fuel is high, the abiabatic flame temperature will be
A. Low
B. High
C. Very high, if the fuel is of low calorific value
D. None of these
Question 68
C/H ratio is the maximum in case of
A. Coal
B. Furnace oil
C. Natural gas
D. Naphtha
Question 69
Optimum preheating temperature for pitch creosote mixture (PCM) which is also termed as C.T.F-200, before atomisation through burners is
A. 200 °F
B. 200 °C
C. 200 °K
D. 200 °R
Question 70
The sequence of absorption in flue gas analysis by Orsat's apparatus is respectively
A. CO₂, O₂, CO
B. CO, O₂, CO₂
C. CO₂, CO, O₂
D. O₂, CO₂, CO
Question 71
Bituminous coal
A. Ignites less easily than anthracite
B. Is generally coking
C. Burns with smoky yellow flame
D. Both B and C
Question 72
The main product of high temperature carbonisation of coal is
A. Coke
B. Ammonia
C. Tar
D. Coke oven gas
Question 73
With increase in the temperature of carbonisation of coal
A. Hydrogen content of coke oven gas increases due to cracking of hydrocarbons
B. Methane content in the coke oven gas decreases and carbon monoxide content increases
C. Calorific value of the coke oven gas decreases due to cracking of hydrocarbons which is not compensated by increase in CO & H? content
D. All of the above
Question 74
Beehive coke oven
A. Facilitates by-products recovery
B. Takes 2-3 days for coking of coal but requires no external fuel for heating
C. Gives larger yield of coke (around 85%) as compared to by-product ovens
D. Produces coke with very poor strength
Question 75
Fuel gases containing hydrocarbons (ie.g. coke oven gas) are not preheated before burning, mainly because
A. The hydrocarbons crack thereby choking and fouling the heat transfer surface by carbon soot
B. It reduces its calorific value tremendously
C. It reduces its flame temperature tremendously
D. There are chances of explosion during preheating
Question 76
Pick out the wrong statement.
A. LPG is also used as fuel for automobiles & small furnaces and for cutting & welding of metals
B. The minimum temperature, at which a petroleum oil vapor catches fire and continues to burn, is called its flash point
C. Each ton of petroleum oil on distillation produces about 30-50 Nm³ of gas
D. Maximum yield of naphthalene is obtained on distillation of crude oil
Question 77
Benzene is used
A. As a motor fuel
B. As an explosive
C. For making insecticides (e.g., DDT, BHC etc.), detergent & rubber (SBR)
D. As a perfume
Question 78
Wood charcoal is obtained by the destructive distillation of wood. It is used in the production of activated carbon, which is not used for the
A. Decolourisation of sugar
B. Solvent recovery from air and gases
C. Absorption of gases and vapor
D. Electrode manufacture
Question 79
Bright coal
A. Contains more than 90% durain
B. Contains more than 90% fussain
C. Contains mainly vitrain & clarain and is generally coking
D. Is non-coking
Question 80
Fuel can be defined as a substance which produces heat by
A. Combustion
B. Nuclear fission
C. Nuclear fusion
D. All of the above
Question 81
Tolerable concentration of toxic carbon monoxide in atmospheric air is about __________ PPm.
A. 50
B. 1000
C. 5000
D. 10000
Question 82
Caking coal is desirable for
A. Burning on travelling grate
B. Coke making
C. Burning on firebars
D. All of the above
Question 83
When steam is passed over coal resulting in the endothermic reaction represent by, C + H₂O = CO + H₂, it is called the __________ of coal.
A. Carbonisation
B. Oxidation
C. Coalification
D. Gasification
Question 84
Calorific value of
A. Light paraffinic fuel oils is equal to that of equivalent olefins
B. N-paraffin is lower than that of iso-paraffins of the same compounds
C. Light paraffinic fuel oils is higher than that of equivalent olefins
D. Light paraffinic fuel oils is lower than that of equivalent olefins
Question 85
As time passes, the calorific value of stored coal
A. Decreases
B. Increases
C. Remains unaltered
D. May increase or decrease (depends on the method of storage)
Question 86
Cannel coal
A. Is non-coking
B. Has a high volatile matter content and burns with a luminous smoky flame
C. Is a non-banded coal which can be ignited easily with a match stick or candle flame, hence is so named
D. All of the above
Question 87
In flue gas analysis by Orsat's apparatus, carbon monoxide is absorbed by
A. Cuprous chloride
B. Potassium hydroxide
C. Alkaline pyrogallol solution
D. None of these
Question 88
Low temperature carbonisation of coal produces
A. Metallurgical coke
B. Soft coke
C. Very low calorific value coke oven gas
D. No by-products
Question 89
High temperature carbonisation of coal produces
A. Inferior coke compared to low temperature carbonisation
B. Less of gases compared to liquid products
C. Large quantity of tar compared to low temperature carbonisation
D. None of these
Question 90
Fuel combustion is never cent per cent efficient due to
A. Incomplete combustion
B. Dry gas/stack gas loss
C. Moisture loss
D. All of the above
Question 91
Coal is pulverised before burning in large capacity boiler furnaces mainly to
A. Ensure its complete combustion
B. Facilitate easy ash removal
C. Enhance its calorific value
D. Provide trouble free operation
Question 92
Spontaneous combustion of coal on storage results due to
A. Inadequate ventilation
B. Low temperature oxidation
C. Storage in large heaps with small surface to volume ratio
D. All of the above
Question 93
Coalification means the
A. Process of conversion of lignite into anthracite
B. Underground gasification of coal
C. Complete combustion of coal
D. Direct hydrogenation of coal
Question 94
Coking coals are invariably
A. Lignites
B. Bituminous coals
C. Semi-anthracites
D. Anthracites
Question 95
Which of the following will generate maximum volume of product of complete combustion (Nm³/Nm³ of fuel) ?
A. Carburetted water gas
B. Blast furnace gas
C. Natural gas
D. Producers
Question 96
Use of excess of combustion air in the combustion of fuels results in
A. Heat losses
B. Long flame
C. Condensation of water vapour from the fuel gas
D. None of these
Question 97
High excess air in combustion of fuels results in
A. Increased fuel consumption
B. Incomplete combustion
C. Smoky flame
D. None of these
Question 98
Combustion of pulverised fuel
A. Requires larger combustion chamber than rich gaseous fuel
B. In a metallurgical furnace does not contaminate the product in the furnace by ash from fuel
C. Suppresses the discharge of fine dust and grit into atmosphere
D. All of the above
Question 99
Correct viscosity of furnace oil at the burner tip for proper atomisation is about 25 centistokes. To reduce the viscosity of high viscosity furnace oil (250 centistokes) to the correct atomisation viscosity (i.e. 25 cst), it should be preheated to about____°C.
A. 70
B. 85
C. 105
D. 145
Question 100
Fixed carbon in coal is defined as
A. That present in volatile matters
B. The total quantity of carbon present in the coal
C. Hundred minus the percentage of volatile matter, ash and moisture
D. The one which is present in the residue after combustion
Question 101
The most matured coal out of the following is
A. Lignite
B. Semi-anthracite
C. Sub-bituminous
D. Bituminous
Question 102
Yield of charcoal in high temperature carbonisation of wood is about __________ percent.
A. 10
B. 25
C. 50
D. 75
Question 103
While the first commercial low temperature coal carbonisation plant is located at Neyveli (in Chennai), the second such plant has been built at
A. Dankuni (West Bengal)
B. Dhanbad
C. Singreni (AP.)
D. Raniganj
Question 104
The maximum adiabatic flame temperature is attained, when the fuel is burnt with
A. Theoretically required amount of air
B. More than theoretically required amount of air
C. Less than theoretically required amount of air
D. Theoretically required amount of oxygen
Question 105
To avoid fire by spontaneous combustion of coal due to its low temperature oxidation, it should be stored in
A. Shallow and small piles
B. Fine sizes without the presence of any lump
C. Closed space without any ventilation facility
D. Large heaps with small surface to volume ratio
Question 106
Which of the following is not applicable to fluidised bed combustion of coal?
A. It can not burn low grade coal
B. It achieves higher fuel combustion efficiency
C. Less heat transfer surface area is required in boilers
D. None of these
Question 107
The heat of combustion of a fuel
A. Is equal to the heat of formation
B. Is always negative
C. Can't be known without calculating it
D. Is always positive
Question 108
The ratio of % total carbon obtained in the ultimate analysis of coke and % fixed carbon obtained in the proximate analysis is always
A. 1
B. < 1
C. > 1
D. Unpredictable
Question 109
Compound coke ovens are those which can be heated by
A. Both steam and electrical power
B. Lean gas (e.g., B.F. gas)
C. Rich gas (e.g., coke oven gas)
D. Both B and C
Question 110
Bomb calorimeter is used to determine the (where, GCV - Gross Calorific Value. NCV - Net Calorific Value.)
A. GCV at constant pressure
B. GCV at constant volume
C. NCV at constant pressure
D. NCV at constant volume
Question 111
Which of the following is a measure of the agglutinating (i.e., binding) property of coal?
A. Thickness of plastic layer
B. Caking index
C. Swelling index
D. Gray-king index
Question 112
Stack heat losses can be minimised by
A. Controlling the excess air
B. Oxygen enrichment of combustion air
C. Using low c.v. fuels
D. Maintaining proper draft in the furnace
Question 113
The gas which contributes maximum to the heating value of natural gas is
A. CO
B. CO₂
C. H₂
D. CH₄
Question 114
Natural draft created by the chimney depends upon
A. Temperature of the flue gas
B. Its height
C. Both A & B
D. Neither A nor B
Question 115
The cooling medium used in dry quenching of coke is
A. Nitrogen
B. Air
C. Phenolic water
D. Carbon dioxide
Question 116
Gasification of the solid fuel converts its organic part into combustible by interaction with air/oxygen and steam so as to obtain a secondary gaseous fuel of high calorific value having no ash. Gasification reactions are normally carried out at about __________ °C.
A. 400-500
B. 900-1000
C. 1400-1500
D. 1700-1800
Question 117
L.D. converter gas (produced in steel plant) comprises mainly of
A. CO (upto 65%) & CO₂
B. CO₂ & H₂
C. CO & O₂
D. CO₂ & O₂
Question 118
Which of the following fuel gases is heavier than air?
A. Blast furnace gas
B. Coke oven gas
C. Natural gas
D. Water gas
Question 119
Shatter index of metallurgical coke on 2 inches and 0.5 inch screen should be respectively around __________ percent.
A. 80 and 97
B. 95 and 100
C. 40 and 70
D. 25 and 97
Question 120
Coke oven gas produced by high temperature carbonisation of coal (as compared to that produced by low temperature carbonisation), has
A. Higher calorific value
B. Lower hydrogen content
C. Both A & B
D. Neither A nor B
Question 121
As the equilibrium moisture content of the coal increases, its
A. Calorific value increases
B. Swelling number decreases
C. Swelling number increases
D. Bulk density decreases
Question 122
Incomplete combustion of fuel in the furnace is judged by high __________ of the flue gases.
A. CO content
B. Dew point
C. CO₂ content
D. O₂ content
Question 123
High sulphur content in a fuel __________ of the flue gases.
A. Decreases the dew point
B. Increases the dew point
C. Reduces the combustion efficiency by limiting the permissible temperature reduction
D. Both B & C
Question 124
Fusion point of coal ash generally varies from 1000 to 1700° C. Ash having fusion point less than __________ °C is liable to form clinker.
A. 1100
B. 1250
C. 1350
D. 1400
Question 125
Coal tar fuel - 200 (CTF 200) is a mixture of
A. Pitch and creosote oil
B. Light oil and pitch
C. Anthracene and crecosote oil
D. Solar oil and pitch
Question 126
Kopper-Totzek coal gasifier (installed in a coal based nitrogeneous fertiliser plant) employs a/an __________ bed gasifier.
A. Entrained
B. Moving
C. Fixed
D. Fluidised
Question 127
Which of the following combustibles is absent in blast furnace gas?
A. H₂
B. CH₄
C. CO
D. None of these
Question 128
Which of the following would require maximum amount of % excess air for complete combustion?
A. Coke oven gas
B. Furnace oil
C. Pulverised coal
D. Lump coal (fixed on chain grate)
Question 129
A sample of natural gas containing 80% methane (CH₄) and rest nitrogen (N₂) is burnt with 20% excess air. With 80% of the combustibles producing CO₂ and the reminder going to CO, the Orsat analysis in volume percent is
A. CO₂ : 6.26, CO : 1.56, O₂ : 3.91, H₂O :15.66, N₂ : 72.60
B. CO₂ : 7.42, CO : 1.86, O₂ : 4.64, N₂:86.02
C. CO₂ : 6.39, CO : 1.60, O₂ : 3.99, H₂O:25.96, N₂:72.06
D. CO₂ : 7.60, CO : 1.90, O₂ : 4.75, N₂ : 85.74
Question 130
Calorific value of gobar gas (containing CH₄ = 60% , H₂ = 10% ; CO₂ = 30%) may be about __________ Kcal/Nm³.
A. 1800
B. 3200
C. 5400
D. 10200
Question 131
Calorific value of dry wood may be around __________ Kcal/kg.
A. 5
B. 50
C. 500
D. 5000
Question 132
Calorific value of bituminous coal may be around __________ Kcal/kg.
A. 500
B. 1500
C. 6500
D. 20000
Question 133
Calorific value of a typical dry anthracite coal may be around __________ Kcal/kg.
A. 1000
B. 4000
C. 8000
D. 15000
Question 134
Ash content in the coke produced from a coking coal having 20% ash may be around __________ percent.
A. 6
B. 12
C. 18
D. 24
Question 135
Pick out the wrong statement.
A. Pulverised fuel can be completely burnt with less percentage of excess air compared to lump coal
B. Low grade coal can be used, but generally high volatile matter coals are more suitable for making pulverised fuel
C. Regulation of furnace temperature and atmosphere (oxidising or reducing) is easily possible with pulverised fuel firing
D. None of these
Question 136
Volatile matter content of metallurgical coke may be around __________ percent.
A. 1-2
B. 10-15
C. 22-26
D. 30-33
Question 137
Quantity of coke produced from metallurgical coal may be around __________ percent.
A. 30
B. 50
C. 75
D. 95
Question 138
Abrasion index of blast furnace coke should be around __________ percent.
A. 20
B. 35
C. 55
D. 80
Question 139
Which of the following is not a binder for coal briquetting?
A. Coal tar
B. Bitumen
C. Molasses
D. None of these
Question 140
Natural draught produced by a chimney depends upon the
A. Density of the chimney gases
B. Height of the chimney
C. Both A & B
D. Neither A nor B
Question 141
In flue gas analysis by Orsat's apparatus, carbon dioxide is absorbed by
A. Potassium hydroxide
B. Dilute potassium carbonate
C. Cuporus chloride
D. Alkaline pyragllol solution
Question 142
For maximum discharge through a chimney, its height should be
A. 200 meters
B. Infinitely long
C. More than 105.7 metres
D. Equal to the height of the hot gas column producing draught
Question 143
Fuel consumption in coke making can be reduced by
A. Preheating, blending and de-ashing the coal
B. Stamped charging of coal
C. Dry quenching of coke
D. All of the above
Question 144
Blast furnace gas compared to coke oven gas has
A. Lower ignition temperature
B. Narrower limit of inflammability
C. Higher calorific value
D. Lower theoretical flame temperature
Question 145
Combustion of pulverised coal as compared to that of lump coal
A. Develops a non-luminous flame
B. Develops a low temperature flame
C. Can be done with less excess air
D. Provides a lower rate of heat release
Question 146
Mott and Wheeler test is conducted on coke to find its
A. Reactivity with O₂
B. Abradability
C. Phosphorus content
D. Volatile matter content
Question 147
Main constituent of natural gas is
A. CH₄ (upto 90%)
B. C₂H₆
C. C₃H₈
D. H₂
Question 148
Method of maintaining fires in furnace during standby periods without undue consumption of fuel is called
A. Back draughting
B. Banking
C. Under pressurising
D. None of these
Question 149
Increase in ash content of blast furnace coke
A. Reduces its consumption in the furnace
B. Increases its consumption in the furnace
C. Does not affect its consumption in the furnace
D. Decreases its hardness and abrasion resistance
Question 150
Pick out the wrong statement.
A. Main constituents of LPG are propane and butane
B. C.V. of natural gas is about 10000 KCal/Nm³
C. C.V. of LPG is about 26000 kcal/Nm³(11500 kcal/kg)
D. L.P.G. is lighter than air
Question 151
Rate of low temperature oxidation of coal due to bad storage conditions
A. Decreases with increase in surface area
B. Does not vary with increase in surface area
C. Is more for low volatile coal compared to high volatile coal
D. Is accelerated by storage in large heaps with small surface to volume ratio
Question 152
During combustion of a gaseous fuel, the presence of a non-luminous flame is an indication of the
A. Incomplete combustion
B. Complete combustion
C. High oxygen in flue gas
D. None of these
Question 153
Which of the following is a primary fuel?
A. Blast furnace coke
B. Gasoline
C. Natural gas
D. Wood charcoal
Question 154
Which of the following is not endothermic?
A. Cracking
B. Reforming
C. Gasification
D. Partial oxidation
Question 155
Which of the following fuel gases will require maximum amount of air for combustion of 1 Nm³ gas ?
A. Blast furnace gas
B. Natural gas
C. Producer gas
D. Water gas
Question 156
During combustion of coal on grate, clinker formation is increased by the
A. Use of thick fire bed
B. Low fusion point of ash (< 1100° C)
C. Use of preheated primary air
D. All of the above
Question 157
A good quality coal should have
A. Low fusion point of ash
B. High ash content
C. High sulphur
D. None of these
Question 158
Coke oven gas is stripped of its H₂S and mercaptans content by
A. Absorption in wash oil
B. Adsorption on bog iron bed
C. Bubbling it through dilute sulphuric acid
D. Adsorption on silica gel
Question 159
Which of the following has the highest flame speed?
A. CO
B. H₂
C. CH₄
D. C₂H₆
Question 160
A good coking coal should have high __________ content.
A. Ash
B. Sulphur & phosphorus
C. Moisture
D. None of these
Question 161
If oxygen content in the flue gas rises too high, fuel is being wasted by
A. Incomplete combustion
B. Dry gas/stack gas loss
C. Moisture loss
D. None of these
Question 162
Coking time in beehive coke oven is about
A. 12 hours
B. 2-3 days
C. One week
D. Two weeks
Question 163
Too much of excess air in combustion results in high
A. Fuel consumption for the same heat load
B. Stack gas temperature
C. Percentage of oxygen in flue gases
D. All of the above
Question 164
Catalyst used in Fischer-Tropsch process is
A. Nickel
B. Zinc oxide
C. Alumina
D. Thorium oxide
Question 165
The cuprous chloride used in orsat apparatus can absorb
A. Only CO
B. Both CO and CO₂
C. Both CO and O₂
D. All of the above
Question 166
Pick out the wrong statement.
A. Cokes of high reactivity are obtained from weakly coking coals
B. Cokes of high reactivity are obtained from strongly coking coals
C. Reactivity of coke is inversely proportional to its absolute density
D. Abrasion index of the coke is a measure of its hardness
Question 167
The pyragallol solution used in orsat apparatus can absorb
A. Only O₂
B. Both O₂ and CO₂
C. Both O₂ and CO
D. All of the above
Question 168
Use of preheated air for combustion of fuel in the furnace, increases the
A. Scale losses of the furnace stock
B. Calorific value of the fuel
C. Flame temperature
D. None of these
Question 169
C.V. (kcal/Nm³) of gaseous fuels __________ with increase in molecular weight.
A. Decreases
B. Increases
C. Remains constant
D. May increase or decrease, depends on combustibles
Question 170
Wobbe index' is a characteristic of
A. Solid fuels
B. Gaseous fuels
C. Liquid fuels
D. Fat coals
Question 171
Pitch creosote mixture (PCM) as compared to furnace oil is a better fuel, because its
A. Emissivity factor is higher
B. Sulphur content is lower
C. Flue gas has lower dew point thereby facilitating more waste heat recovery
D. All of the above
Question 172
The calorific value of natural gas is about __________ kcal/Nm³.
A. 10, 000
B. 2500
C. 25, 000
D. 35, 000
Question 173
Calorific value of wood gas is about __________ kcal/Nm³.
A. 1500
B. 3300
C. 5400
D. 8500
Question 174
Calorific value of coke even gas produced by low temperature carbonisation of coal is about __________ Kcal/Nm³.
A. 4000
B. 2500
C. 6500
D. 10000
Question 175
The calorific value of 'LPG' (50% propane + 50% butane) is about __________ kcal/Nm³.
A. 5000
B. 25, 000
C. 10, 000
D. 15, 000
Question 176
The calorific value of producer gas is around __________ kcal/Nm³
A. 1300
B. 500
C. 4500
D. 9000
Question 177
Yield of pitch from distillation of high temperature tar is around __________ percent.
A. 10
B. 25
C. 65
D. 90
Question 178
Supply of excess air for complete combustion of fuel is necessitated to facilitate
A. Its thorough mixing with air
B. Attainment of chemical equilibrium
C. Attainment of high temperature
D. None of these
Question 179
In high temperature carbonisation of coal compared to low temperature carbonisation
A. Yield of ammonia is less
B. Aromatic content of tar is low
C. H₂ content in the coke oven gas is more
D. Calorific value of the coke oven gas is lower
Question 180
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. 3-5
B. 25-30
C. 60-65
D. 95-100
Question 181
Dry air requirement for burning 1 Nm³ of CO to CO₂ may be around __________ Nm³.
A. 2.4
B. 1.75
C. 0.87
D. 11.4
Question 182
Low temperature oxidation and spontaneous combustion of freshly mined coal is accentuated, if
A. It contains large amount of volatile matter
B. It is stored in tall heaps
C. Smaller fines are stored in large quantity
D. All of the above
Question 183
Pick out the wrong statement.
A. Indian coals on an average contain 25-30% ash as against 10-12% ash in imported coking coal
B. Ammonia is recovered in the form of ammonium sulphate in direct process of by-product recovery
C. A high swelling index number of coking coal indicates poor caking properties of coal
D. Wash oil is used for scrubbing benzol from coke oven gas
Question 184
With increase in moisture content of coal, its
A. Calorific value increases sometimes
B. Bulk density always decreases
C. Clinkering tendency during combustion increases
D. None of these
Question 185
Gray King Assay and Swelling Index of a coal is a measure of its
A. Swelling characteristics
B. Abradability
C. Agglutinating properties
D. Resistance to impact breakage
Question 186
Caking index of a coal is a measure of its
A. Abradability
B. Reactivity
C. Agglutinating (binding) properties
D. Porosity
Question 187
Micum Index of a coke is a measure of its
A. Reactivity
B. Porosity
C. Bulk density
D. Hardness & strength
Question 188
Weathering of coal during storage causes
A. Reduction in coal size
B. Increase in its friability
C. Decrease in its caking capacity
D. All of the above
Question 189
Low temperature oxidation of coal is accelerated by the
A. Storage in large heaps
B. Storage in compressed piles
C. Absence of porous or friable particles
D. All of the above
Question 190
Washing of coal is done to reduce the
A. Inherent impurities
B. Adhering impurities
C. Mineral matter
D. Both B and C
Question 191
Low temperature oxidation of stored coal results in the
A. Decrease in its caking power & calorific value
B. Decrease in its carbon & hydrogen content
C. Increase in its oxygen content
D. All of the above
Question 192
Adiabatic flame temperature of a fuel is dependent on the initial temperature of
A. Fuel
B. Air
C. Both A & B
D. Neither A nor B
Question 193
Pure carbon is completely burnt in oxygen. The flue gas analysis is 70%CO₂, 20%CO and 10%O₂. The percent excess oxygen used is
A. 20
B. 12.5
C. 0
D. 10
Question 194
Which of the following is not a product of tar distillation?
A. Phenol & naphthalene
B. Benzol & pitch
C. Anthracene & creosote
D. None of these
Question 195
Steam is intermittently admitted into the fuel bed during the production of producer gas to
A. Convert CO to CO₂
B. Increase the combustion rate
C. Increase the gas production rate
D. Minimise the chances of clinker formation
Question 196
High rate of heating of coke ovens
A. May damage its walls due to abrupt excessive swelling of coal
B. Produces larger size coke
C. Increases the time of carbonisation
D. None of these
Question 197
By-products are __________ recovered in 'Beehive ovens'.
A. Fully
B. Partially
C. Not at all
D. Negligibly
Question 198
Naphthalene is removed from coke oven gas by
A. Scrubbing with wash oil (a petroleum product)
B. Adsorbing on bog iron bed
C. Absorbing in vetro-coke solution
D. None of these
Question 199
__________ of the coal is the basis for Seylor's coal classification.
A. Proximate analysis
B. Ultimate analysis
C. Caking index
D. Calorific value
Question 200
Low temperature oxidation of coal during storage does not decrease its
A. Oxygen content
B. Caking power
C. Calorific value
D. None of these
Question 201
Pick out the wrong statement.
A. Percentage of ash in coke produced from medium coking coal is more than that in coal
B. The calorific value (kcal/Nm³) of coke oven gas reduces on removal of hydrogen from it by cryogenic method
C. Ash is normally removed as
D. Coal based fertiliser plants in India at Talcher (Orissa) and Ramagundam (A.P) employ Kopper-Totzek process of coal gasification
Question 202
Low temperature carbonisation of coal takes place at __________ °C.
A. 300
B. 1100
C. 700
D. 150
Question 203
High temperature carbonisation of coal takes place at __________ °C.
A. 2000
B. 600
C. 1100
D. 1600
Question 204
Actual flame temperature is always lower than the adiabatic flame temperature, because there is
A. No possibility of obtaining complete combustion at high temperature
B. Always loss of heat from the flame
C. Both A & B
D. Neither A nor B
Question 205
The ratio of maximum adiabatic flame temperature in air to that in pure oxygen is always
A. 1
B. <1
C. > 1
D. Unpredicatable
Question 206
Sometimes water is sprayed during coal charging in the coke oven, which helps in
A. Prevention of clinker formation in the oven
B. Controlling the dust nuisance while charging the coal
C. Reducing the cracking of hydrocarbons in the gas and increasing the percentage of CO & H₂ in the gas (due to the endothermic reaction represented by C + H₂O = CO + H₂)
D. All of the above
Question 207
The main drawback of supplying more excess air in the combustion of fuel is the
A. Excessive power requirement of air blower
B. Enhanced sensible heat loss in the flue gas
C. Intermittant and uncontrolled combustion of the fuel
D. High exit flue gas temperature from the furnace
Question 208
Which of the following fuel gases has the highest calorific value ?
A. Natural gas
B. Coal bed methane (CBM)
C. Liquefied petroleum gas (LPG)
D. Sewage gas
Question 209
Which of the following has the highest calorific value?
A. Lignite
B. Sub-bituminous coal
C. Anthracite
D. Peat
Question 210
Which of the following coke has the least percentage of ash?
A. Petroleum coke
B. Beehive coke
C. Foundary coke
D. Metallurgical coke
Question 211
Which will have the least volatile matter and hence will be the most difficult to ignite?
A. Bituminous coal
B. Coke
C. Semi-bituminous coal
D. Aanthracite
Question 212
Ratio of primary air to secondary air increases with increase in the rank of coal, because the
A. High rank coals have higher amount of volatile matter
B. Ratio of fixed carbon to volatile matter increases
C. Oxygen content progressively decreases
D. Calorific value of the coal increases
Question 213
White flue gas (resembling steam) coming out of the chimney of a thermal power plant indicates that the fuel used in the boiler furnace is
A. Tar
B. Coke oven gas
C. Pitch
D. Pulverised coke
Question 214
Calorific value of both the solid & liquid fuels can be determined by using __________ calorimeter.
A. Junker's
B. Bomb
C. Boy's
D. None of these
Question 215
Oxygen percentage (by weight) in atmospheric air is
A. 19
B. 21
C. 23
D. 29
Question 216
Which of the following can be made into briquettes without the use of a binder?
A. Lignite
B. Bituminous coal
C. Anthracite coal
D. None of these
Question 217
Octane number of 2, 2, 4 - trimethyl pen-tane is
A. 0
B. 100
C. In between 0 and 100
D. More than 100
Question 218
During coking of coal, the ash content (percentage)
A. Increases
B. Decreases
C. Remains constant
D. None of these
Question 219
Abel apparatus is used for those oils, whose flash points are___°F.
A. <120
B. >120
C. >280
D. 300-600
Question 220
Pick out the wrong statement.
A. Theoretical flame temperature is the temperature attained by the products of combustion, when the fuel is burned without loss or gain of heat
B. Burning the fuel with theoretically required amount of pure oxygen results in attainment of maximum adiabatic flame temperature
C. Burning the fuel with excess pure oxygen results in maximum theoretical flame temperature
D. Adiabatic flame temperatures of actual combustions are always less than the maximum values
Question 221
__________ is used as jet engine fuel.
A. Petrol
B. Diesel
C. Kerosene
D. LPG
Question 222
Gas yield in the Kopper-Totzek coal gasifier is about __________ Nm³/ton coal (ash = 35%).
A. 150
B. 1500
C. 3500
D. 5000
Question 223
Coal containing large quantity of __________ are difficult to wash.
A. Ash
B. Inherent mineral matter
C. Free impurities
D. Volatile matter
Question 224
Gobar gas is produced by the __________ of 'gobar' (cow dung).
A. Hydrolysis
B. Fermentation
C. Oxidation
D. Dehydration
Question 225
Preheating of __________ the flame temperature.
A. The gaseous fuel before combustion decreases
B. Combustion air decreases
C. Either the fuel or the air or both, increases
D. Either the fuel or the air does not affect
Question 226
Gross heating value of coal is __________ the net heating value.
A. Higher than
B. Lower than
C. Same as
D. None of these
Question 227
Yield of coke oven gas in low temperature carbonisation of coal is about __________ Nm³ /ton of dry coal.
A. 60
B. 160
C. 500
D. 750
Question 228
Yield of blast furnace gas is about __________ Nm³ /ton of pig iron.
A. 300
B. 2000
C. 5000
D. 10000
Question 229
Degree of carbonisation of coal during coke making can be roughly judged by the __________ of the coke produced.
A. Colour
B. Moisture content
C. Ash content
D. Volatile matter
Question 230
With increase in moisture content of coal, its
A. Calorific value increases
B. Caking properties diminish
C. Swelling during carbonisation becomes excessive
D. None of these
Question 231
The average molecular weight of a flue gas having the composition by volume as CO₂ = 25%, O₂ = 25%, N₂ = 50% will be
A. 27.6
B. 23
C. 47.3
D. 42.9
Question 232
High sulphur (4-6%) coal in India are found in
A. Assam
B. Andhra Pradesh
C. Bengal
D. Madhya Pradesh
Question 233
Which of the following is not used as a binder in coal briquetting?
A. Tar
B. Molasses
C. Pitch
D. Line
Question 234
A coal with high ash content
A. Has higher calorific value
B. Is harder and stronger
C. Is not subjected to washing
D. Has low quantity of mineral matter
Question 235
Artificial draught produced by a fan can be controlled by the
A. Speed of the fan
B. Damper
C. Variation in the pitch of the fan blades
D. All of the above
Question 236
A good metallurgical coke
A. Should have high porosity
B. Should be brittle
C. Must contain moderate quantities of ash, moisture, sulphur and volatile matters
D. Should have low fusion point of its ash
Question 237
Pick out the wrong statement.
A. High concentration of oxygen in flue gas means high stack loss
B. Gaseous fuels require the least % excess air for complete combustion
C. The ratio of fixed carbon to volatile matter percentage in coal is called its 'fuel ratio'
D. Calorific value of natural gas is more than that of LPG
Question 238
Very __________ coals are completely devoid of cokability i.e, it is non coking.
A. Young
B. Mature
C. Both A & B
D. Neither A nor B
Question 239
Dust content in raw blast furnace gas is about __________ gm/Nm³ , hence it is cleaned to the dust level of about < 10 mg /Nm³ before use.
A. 15-30
B. 1-2
C. 70-100
D. 150-200
Question 240
Coke oven gas is a better fuel than blast furnace gas, because of its higher
A. Calorific value, cleanliness and relatively low distribution cost (due to its low specific gravity)
B. Adiabatic flame temperature
C. Heat release rate (thus requiring smaller combustion chamber)
D. All of the above
Question 241
The main advantage of forced draft over natural draft is that
A. Combustion of fuel is complete
B. Smaller height chimney can be used
C. Furnace control is easier
D. All of the above
Question 242
A particular coal is said to be free burning when it
A. Burns completely
B. Gives smokeless burning
C. Shows little or no fusing action
D. None of these
Question 243
Main constituents of benzol are
A. Benzene, toluene & xylene
B. Tar & creosote
C. Ammonia & phenol
D. Anthracene & phenol
Question 244
Grindability index of a coal is 100. It implies that the
A. Coal can be pulverised with great difficulty
B. Coal can't be pulverised
C. Coal can be easily pulverised
D. Power consumption in grinding the coal will be very high
Question 245
Heat penetration rate in narrow coke ovens in high temperature carbonisation of coal is around __________ cm/hr.
A. 2.5
B. 0.5
C. 10
D. 20
Question 246
The reaction, C + CO₂ ⟷ 2CO, taking place during coal gasification is called the __________ reaction. n.
A. Neumann reversal
B. Shift conversion
C. Boudouard
D. Reduction
Question 247
Which of the following constituents of a fuel does not contribute to its calorific value on combustion?
A. Hydrogen
B. Sulphur
C. Carbon
D. None of these
Question 248
Which of the following fuels has the highest calorific value per unit mass (kcal/kg)?
A. Coal
B. Kerosene
C. Natural gas
D. Furnace oil
Question 249
Tar is a better fuel than furnace oil, because of its
A. Higher calorific value
B. Lower sulphur content
C. Higher emissivity (0.8 - 0.9) resulting in higher radiation heat transfer rate
D. Both A & B
Question 250
When incomplete combustion loss is high, the flue gas analysis shows large amount of
A. CO₂
B. CO
C. O₂
D. C
Question 251
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 these
Question 252
Benzol is used
A. As a motor fuel blend
B. For producing benzene, tolune & xylene by its distillation
C. Both A & B
D. Neither A nor B
Question 253
Coking time in a commercial high temperature coal carbonisation plant is about __________ hours.
A. 6
B. 18
C. 28
D. 36
Question 254
Pick out the wrong statement.
A. Angle of repose of coal increases with its increasing size
B. Specific gravity of coal increases with its increasing maturity
C. Refractive index and reflectance of coal increases with the increasing rank of coal
D. Specific heat of coal decreases with increases in the volatile matter and decrease in the C/H ratio of coal
Question 255
A coal with high __________ content, would ignite most easily.
A. Fixed carbon
B. Volatile matter
C. Ash
D. Oxygen
Question 256
Main constituents of purified Lurgi gas are
A. H₂, CmHn & CO₂
B. CO, H₂ & CH₄
C. CO₂, O₂ & CO
D. N₂, H₂ & CO₂
Question 257
Preheating of a gaseous fuel results in increased
A. Flame length
B. Flame temperature
C. Quantity of flue gas
D. Ignition temperature
Question 258
The shift conversion reaction taking place during water gas manufacture is given by
A. C + H₂O ⟷ CO + H₂
B. C + 2H₂O ⟷ CO₂ + 2H₂
C. CO + H₂O ⟷ CO₂ + H₂
D. None of these
Question 259
In high temperature carbonisation (as compared to low temperature carbonisation) of coal
A. Coke oven gas yield is more
B. Tar yield is less but free carbon in tar is more
C. Calorific value of coke oven gas is less
D. All of the above
Question 260
In low temperature carbonisation (as compared to high temperature carbonisation) of coal
A. Ammonia yield is more
B. Aliphatic tar is produced
C. Free carbon in tar is more
D. All of the above
Question 261
The main function of primary air in pulverised coal fired burner is to
A. Burn CO to CO₂
B. Dry and transport the coal
C. Have proper combustion by supplying it around the burner
D. Preheat the tertiary air used for complete combustion of CO to CO₂
Question 262
Which of the following is the most important deterrents to an extended use of pulverised coal in boiler firing?
A. Ash disposal problem
B. Excessive fly-ash discharge from the stack
C. High power consumption in its transportation
D. Erosion of induced draft fan blades
Question 263
Ash content in the middling coal (a byproduct of coal washeries) in India ranges between __________ percent.
A. 15 to 25
B. 35 to 45
C. 55 to 75
D. 75
Question 264
Which of the following gaseous fuels has the highest net calorific value (kcal/Nm³)?
A. Producer gas
B. Carburetted water gas
C. Natural gas
D. Liquified petroleum gas
Question 265
Gray-King Assay and Roga Index of coal is a measure of its
A. Abradability
B. Grindability
C. Weathering properties
D. Caking and swelling properties
Question 266
Which of the following is a rich fuel gas?
A. Producer gas
B. Coal gas from underground gasification of coal
C. Refinery gases
D. None of these
Question 267
Turndown ratio of a gas burner is equal to the
A. Maximum to minimum heat input ratio
B. Maximum to minimum permissible gas flow rate
C. Both A & B
D. Minimum to maximum heat input ratio
Question 268
__________ process is meant for direct hydrogenation of coal to produce liquid fuel.
A. Fischer-Tropsch
B. Bergius
C. Lurgi
D. None of these
Question 269
Advantages of fluidised bed combustion are
A. Reduced NOx formation in flue gas
B. Lower furnace operating temperature
C. High heat transfer rate
D. All of the above
Question 270
In general, the limit of inflammability/explosion limit of fuel gases is widened by the
A. Increase in gas pressure
B. Increase in temperature (i.e. preheating)
C. Use of pure oxygen for combustion instead of air
D. All of the above
Question 271
Temperature of coke oven gas just before entering into saturator (for recovery of NH₃) is about __________ °C.
A. 30
B. 65
C. 120
D. 180
Question 272
Shatter index of the coke is a measure of its
A. Strength
B. Bulk density
C. Reactivity
D. None of these
Question 273
A certain thickness of the coal, if stored unscientifically on soft (katcha) ground having no metallic/concrete flooring gets sunked into the ground, which is termed as the 'carpet loss'. The carpet loss may be of the order of __________ cms.
A. 1 to 2
B. 3 to 4
C. 5 to 15
D. 20 to 40
Question 274
Fat' coal means a coal having
A. Low calorific value
B. High volatile matter
C. Low ash content
D. Non smoking tendency
Question 275
Which of the following is a lean fuel gas?
A. Coke oven gas
B. LPG
C. Blast furnace gas
D. Natural gas
Question 276
Which of the following is unsuitable fuel for producer gas manufacture?
A. Coke
B. Anthracite
C. Coal having low fusion point of its ash
D. Coal having high fusion point of its ash
Question 277
Preheating of coal charge for the coke ovens reduces the
A. Time of carbonisation
B. Yield of gas and tar
C. Fuel consumption in coking
D. All of the above
Question 278
Fossil fuels mean
A. Solid fuels
B. Liquid fuels
C. Those fuels which are found in the crust of earth
D. Premature fuels with low calorific value
Question 279
Froth floatation is used for
A. Washing fine coal dust (< 0.5 mm size)
B. Washing lump coal (> 80 mm size)
C. Removing ash from the coal based on difference in specific gravity of coal and ash
D. All of the above
Question 280
Main use of soft coke is as __________ fuel.
A. Domestic
B. Blastfurnace
C. Foundary
D. None of these
Question 281
Fussain
A. Is friable, charcoal like substance
B. Has highest fixed carbon and lowest volatile matter content of all the four banded components of coal
C. Is non-coking, but when blended with highly coking coal, controls its swelling and produces high strength coke on carbonisation
D. All of the above
Question 282
Deficiency of combustion air during combustion of a gaseous fuel
A. Lengthens the flame
B. Causes heat loss of fuel by its partial combustion
C. Both A & B
D. Shortens the flame
Question 283
Which of the following is not a manufactured fuel ?
A. Furnace oil
B. Bagasse
C. Semi-coke
D. Kerosene
Question 284
Preheating of combustion air is done to
A. Increase the adiabatic flame temperature
B. Increase the calorific value of the fuel
C. Complete the combustion of fuel
D. Reduce its requirement for effecting the complete combustion
Question 285
Theoretical flame temperature of a fuel is that temperature which is attained, when the fuel is completely burnt 'using theoretical amount of air in
A. Air
B. Oxygen
C. Either A or B
D. Either A or C without gain or loss of heat
Question 286
With increase in the time of carbonisation at a particular temperature (say 1000°C), the __________ percentage in coke oven gas increases.
A. Hydrogen
B. Methane
C. Unsaturated hydrocarbons
D. All of the above
Question 287
Assam coals suffers mainly from the disadvantage of high __________ content.
A. Ash
B. Volatile matter
C. Sulphur (4-6%)
D. Moisture
Question 288
Incomplete combustion of a fuel is characterised by the high __________ in the flue gas.
A. Smoke
B. Temperature
C. Oxygen
D. Carbon monoxide
Question 289
Cannel coal and boghead coal are the examples of
A. Humic coals
B. Liptobiolites
C. Sapropelic coals
D. None of these
Question 290
The calorific value is the highest out of the following for
A. Producer gas
B. Water gas
C. Coke oven gas
D. Blast furnace gas
Question 291
Which of the following is coking?
A. Vitrain
B. Fussain
C. Both A & B
D. Neither A nor B
Question 292
Safe condition for storage of high V.M. bituminous coal is that
A. Height of the coal heap should be < 3 metres
B. Maximum 200 tons should be stored in a heap
C. Both A and B
D. Neither A nor B
Question 293
A coal having high volatile matter content will
A. Give less yield of tar and gas on carbonisation
B. Burn with a small non-smoky flame
C. Have a very high calorific value
D. None of these
Question 294
Hard coke is manufactured from
A. Lignite
B. Bituminous coal
C. Semi-anthracite
D. Anthracite
Question 295
Hard pitch is used for making
A. Pulverised fuel
B. Perfumes
C. Insecticides
D. Plastics
Question 296
Traces of tar fog present in the coke oven gas is removed by
A. Cyclone separator
B. Wet packed scrubber
C. Electrostatic precipitator
D. Washing with monoethanolamine
Question 297
Which of the following has the highest heat of combustion?
A. H₂
B. CO
C. CH₄
D. C₂H₆
Question 298
Which of the following reactions occuring during coal gasification is called the Neumann reversal reaction?
A. 2CO ⟷ C + CO₂
B. CO + H₂O ⟷ CO₂ + H₂
C. C + H₂O ⟷ CO + H₂
D. C + 2H₂O ⟷ CO₂ + 2H₂
Question 299
Overfire burning in a furnace is a phenomenon characterised by the
A. Supply of excess fuel
B. Supply of excess air
C. Burning of carbon monoxide and other incombustibles in upper zone of furnace by supplying more air
D. None of these
Question 300
Which of the following has the highest theoretical flame temperature ?
A. Blast furnace gas
B. Hydrogen
C. Acetylene
D. Coke oven gas
Question 301
Fischer-Tropsch method aims at the
A. Gasification of coal
B. Synthesis of gasoline (from water gas)
C. Hydrogenation of coal to produce gasoline
D. None of these
Question 302
The liquid used for the washing of coal in an industrial coal washery is a mixture of water and
A. Carbon tetrachloride
B. Sand (40%)
C. Mineral oil of high viscosity & specific gravity (1.6)
D. None of these
Question 303
A coal having high amount of volatile matter
A. Would require smaller combustion chamber
B. Produces very little of tar and gas on carbonisation
C. Ignites easily and burns with long smoky flame
D. All of the above
Question 304
High ash coals
A. Are soft & friable (poor strength and size stability)
B. Require longer time of carbonisation as ash offers resistance to heat transfer
C. Produce larger quantity of coke oven gas
D. None of these
Question 305
High ash containing coke
A. Produces more slag when used in the blast furnace
B. Has poor strength and abrasion resistance
C. Is desirable in producer gas manufacture
D. None of these
Question 306
Presence of free moisture in coal during its high temperature carbonisation
A. Reduces the coking time
B. Protects the volatile products from pyrolysis (cracking) in the presence of hot coke and hot oven walls
C. Increases the loss of fine coal dust from the ovens when charging
D. None of these
Question 307
Which of the following gaseous fuels is likely to have the highest gross calorific value?
A. Sewage gas
B. LPG
C. Producer gas
D. Natural gas
Question 308
Highly caking coals
A. Produce weak coke
B. Produce strong coke
C. May damage the coke oven walls during carbonisation
D. Both B and C
Question 309
Flue gas obtained on complete combustion of pure acetylene (a hydrocarbon fuel) will contain
A. CO
B. CO₂
C. H₂O
D. Both B & C
Question 310
For the case of a fuel gas undergoing combustion with air, if the air/fuel ratio is increased, the adiabatic flame temperature will
A. Increase
B. Decrease
C. Increase or decrease depending on the fuel type
D. Not change
Question 311
Lurgi gasifier (high pressure gasifier) as compared to Kopper Totzek gasifier (atmospheric pressure gasifier) produces
A. Higher amount of methane
B. Lower amount of hydrogen
C. Both A & B
D. Higher amount of both methane and hydrogen
Question 312
Out of the following fuels, the difference between the net and gross calorific value is maximum in case of
A. Pitch
B. Fuel oil
C. Blast furnace gas
D. Bituminous coal
Question 313
A good metallurgical coke should have very low
A. Sulphur & phosphorous content
B. Porosity
C. Fusion point of its ash
D. Hardness & strength
Question 314
Which is the most matured coal?
A. Lignite
B. Bituminous
C. Semi-anthracite
D. Anthracite
Question 315
Coke compared to the coal from which it has been made, contains
A. Less volatile matter
B. More carbon
C. Greater percentage of ash
D. All of the above
Question 316
Higher fuel combustion efficiency can not be achieved by
A. Preheating of fuel gases & combustion air
B. Reducing sulphur content in the fuel
C. Adopting proper fuel firing technique & fuel preparation
D. Supplying correct amount of combustion air
Question 317
Pick out the correct statement.
A. Oxygen content decreases from lignite to bituminous coal as the coalification increases
B. The less the oxygen content, better is the coal, as it reduces the calorific value
C. With increase in oxygen content, moisture holding capacity of coal increases and the caking power decreases
D. All of the above
Question 318
Higher efficiency in the combustion of solid fuel can not be achieved by
A. Proper fuel preparation
B. Keeping the flue gas exhaust temperature very high
C. Adopting efficient-fuel firing technique & equipment
D. Supplying correct quantity of combustion air
Question 319
A coal gasifier opearating at 20 atm. (e.g. Lugri gasifier) as compared to one operating at atmospheric pressure (e.g. Kopper-Totzek or Winkler gasifier) will produce a gas having
A. Higher methane content and thus higher calorific value
B. Higher carbon monoxide content
C. Lower carbon dioxide content
D. None of these
Question 320
Which of the following has the highest gross calorific value?
A. Blast furnace gas
B. Coke oven gas
C. Carburetted water gas
D. Oil refinery gas
Question 321
Highly reactive coke have lower
A. Porosity
B. Coke reactivity index (CRI)
C. Critical air blast (CAB) value
D. Both B and C
Question 322
Which of the following accounts for maximum energy loss in a boiler?
A. Flue gases
B. Ash content in the fuel
C. Incomplete combustion
D. Unburnt carbon in flue gases
Question 323
Pulverised coal used in boiler firing need not have
A. Less moisture content
B. High fusion point of its ash
C. High bulk density
D. Lower ash content
Question 324
Mineral matter, 'M' and ash percentage 'A' in coal are roughly related as
A. M = 1.8 A
B. M = 0.5 A
C. M = 1.1 A
D. M = A
Question 325
Percentage of hydrogen in coke oven gas may be around
A. 10
B. 25
C. 45
D. 60
Question 326
Percentage of methane in coke oven gas may be around
A. 5
B. 15
C. 25
D. 50
Question 327
In Lurgi coal gasifier,
A. Coking coals cannot be used
B. Low carbon conversion efficiency is achieved
C. Entrainment of solids is higher
D. Larger quantity of coal can be processed
Question 328
During coal carbonisation process, the conversion of semi-coke to coke is accompanied by an increase in the __________ of the mass.
A. Density
B. Porosity
C. Electrical resistivity
D. None of these
Question 329
__________ present in coal is not determined in its ultimate analysis.
A. Fixed carbon
B. Total carbon
C. Hydrogen
D. Nitrogen
Question 330
Prime coking coal is always blended with medium or non- coking coal before ear-bonisation
A. To check against its excessive swelling during heating, which may exert high pressure and damage coke oven walls
B. Because, it alone produces unreactive coke
C. Both A & B
D. Neither A nor B
Question 331
Which of the following is not a by-product fuel?
A. Pitch
B. Blast furnace gas
C. Petrol
D. Refinery gas
Question 332
Which of the following is the most reactive (as regards the formation of CO + H₂ from C + H₂O) ?
A. Blast furnace coke
B. Low temperature coke
C. Anthracite coal
D. Sub-bituminous coal
Question 333
For long flame and easy ignition, the coal used should have
A. High volatile matter
B. Low ash
C. High calorific value
D. High ash
Question 334
The calorific value of L.D. converter gas is about __________ Kcal/Nm³ .
A. 1800
B. 800
C. 4500
D. 10000
Question 335
Emission of dense white smoke out of the chimney of a thermal power plant is an indication of the use of
A. Less air for combustion
B. Correct amount of air for combustion
C. Too much air for combustion
D. Pulverised coal in boilers
Question 336
Calorific value of coke oven gas is around __________ Kcal/Nm³.
A. 900
B. 4200
C. 7500
D. 2000
Question 337
Calorific value of of blast furnace gas is around __________ KCal/Nm³.
A. 850
B. 1800
C. 4200
D. 6500
Question 338
Presence of free moisture in coal is most disadvantageous during
A. Its pulverisation (as it requires more power)
B. Combustion of fire slacks on the grates
C. Handling (e.g. when emptying wagons)
D. None of these
Question 339
Which of the following is not a 'manufactured' fuel?
A. LPG
B. Coal briquettes
C. Tar
D. Colloidal fuels
Question 340
Coal tar (produced by high temperature carbonisation) is the main source of
A. Aromatic compounds
B. Alphatic compounds
C. Paraffins
D. Olefins
Question 341
The main reason for making the copper calorimeter (used in bomb calorimeter) silvery white and shining/polished is to
A. Minimise its corrosion
B. Avoid radiation heat loss
C. Make it look attractive
D. None of these
Question 342
Largest constituent of blast furnace gas is
A. N₂
B. CO
C. CO₂
D. H₂
Question 343
(64-132) rank coal (ASTM) means a coal with 64%
A. Fixed carbon and having a heat value of 13, 200 BTU/1b
B. Ash and a heating value of 13, 200 BTU/1b
C. Fixed carbon and a heating value of 132 BTU/1b
D. None of these
Question 344
(64-132) rank coal (ASTM) means a coal with 64%
A. Fixed carbon and having a heating value around 13, 200 BTU/1b
B. Ash and heating value around 13, 200 BTU/1b
C. Fixed carbon and heating value around 132 BTU/1b
D. None of these
Question 345
Mineral matter content (M) and ash content (A) in coal are approximately related as
A. M = 1.1A
B. M = A
C. M = 1.5A
D. M = 2A
Question 346
Calorific value of furnace oil is about __________ Kcal/kg.
A. 10000
B. 15000
C. 5000
D. 20000
Question 347
Which of the following petrological constitutes is responsible for bright and lustrous black band of bituminous coal?
A. Vitrain
B. Clarain
C. Durain
D. Fussain
Question 348
Percentage of nitrogen in blast furnace gas may be around
A. 5
B. 25
C. 55
D. 80
Question 349
Percentage of carbon monoxide in blast furnace gas may be around
A. 8
B. 14
C. 22
D. 52
Question 350
About __________ Nm³ of air will be required for the complete combustion of 2Nm³ of CO.
A. 2
B. 3
C. 5
D. 1
Question 351
Lignite is
A. A high rank coal
B. A coking coal
C. Can be used for gasification and steam generation
D. A black banded coal which burns with a non-smoky yellowish flame
Question 352
Which of the following is called "blue gas"?
A. Coke oven gas
B. Water gas
C. Natural gas
D. Producer gas
Question 353
Low temperature carbonisation
A. Is mainly for producing the smokeless domestic coke
B. Is meant for the production of 'metallurgical coke'
C. Produces higher quantity of gas than high temperature carbonisation
D. Produces less quantity of tar than high temperature carbonisation
Question 354
Eschka mixture, which is used for the determination of sulphur in coal, is a mixture of
A. MgO & Na₂CO₃
B. MgSO₄ & BaCl₂
C. BaSO₄ & NaCl
D. MgCO₃ & NaCl
Question 355
__________ prohibits the use of alcohols directly in petrol engines.
A. Low octane number
B. High cost & availability
C. Low flash point
D. Low calorific value
Question 356
Gross and net calorific value of a fuel will be the same
A. If its ash content is zero
B. Ifits carbon content is very low
C. If its hydrogen/hydrogen compound content is zero
D. Under no circumstances
Question 357
Out of the following fuels, the difference between gross and net calorific value will be minimum in case of
A. Coke oven gas
B. Water gas
C. Natural gas
D. Blast furnace gas
Question 358
Desirable "Micum Index" values of metal-lurical coke are
A. M40 > 78% and M10 < 10%
B. M40 > 4% and M10 < 80%
C. M40 > 10% and M10 < 78%
D. M40 > 98% and M10 < 2%
Question 359
Caking index of the coal blend used for the manufacture of metallurgical coke should be around
A. 5
B. 21
C. 40
D. 48
Question 360
Height of coke oven is limited (say maximum upto 7 metres) mainly by the
A. Problem of uniform heating along its height
B. Structural strength of silica bricks
C. Problem in door cleaning
D. Buckling of ram of pusher car at the time of coke pushing
Question 361
Which of the following fuels is generally not used in thermal power plant boiler firing?
A. Furnace oil, light diesel oil and tar/PCM
B. Pulverised coking coal
C. Coal middling from washeries
D. B.F. gas, coke oven gas and L.D. converter gas
Question 362
Bulk density of pulverised coal may be about __________ kg/m³.
A. 100
B. 500
C. 1000
D. 1500
Question 363
Quantity of coke oven gas produced by high temperature carbonisation of one ton of dry coal may be around __________ Nm³.
A. 30
B. 300
C. 3000
D. 30, 000
Question 364
A sooty flame can be made non-luminous by
A. Admitting more gas
B. Shutting gas supply
C. Admitting more air
D. Shutting air supply
Question 365
The maximum adiabatic flame temperature in air is __________ the maximum flame temperature in pure oxygen.
A. Lower than
B. Higher than
C. Same as
D. Not related to
Question 366
Coke oven gas burns with an yellowish flame, because of the presence of
A. CO₂
B. CH₄
C. H₂
D. NH₃
Question 367
Blast furnace gas burns with a bluish flame, because of the presence of
A. CO
B. CH₄
C. CO₂
D. S
Question 368
With increase in C/H ratio of a fuel, the amount of CO₂ formed on its complete combustion
A. Increases
B. Decreases
C. Remains same
D. Either A or B, depends on other factors
Question 369
Most of the coking coals are
A. Anthracite
B. Bituminous
C. Lignite
D. None of these
Question 370
Coke oven gas compared to blast furnace gas is
A. More explosive and inflammable
B. Less poisonous
C. Lighter
D. All of the above
Question 371
High pressure coal gasification is employed in __________ process.
A. Lurgi
B. Kopper-Totzek
C. Winkler
D. None of these
Question 372
In low temperature carbonisation of coal as compared to high temperature carbonisation __________ produced is less.
A. Difference in gross & net calorific value of the coke oven gas
B. Free carbon content in tar
C. Yield percentage of coke
D. Yield of ammonia present in coke oven gas
Question 373
Which adsorbant is used for removing sulphur compounds (S Q, H₂S, RSH etc.) removal from coke oven gas in by-products recovery plant ?
A. Silica gel
B. Diatomaceous earth
C. Basalt
D. Bog iron (i.e., moist ferric hydroxide)
Question 374
Number of macrocomponents present in coal according to Stopes are
A. Four
B. Five
C. Six
D. Two
Question 375
Function of secondary air in pulverised coal firing is to
A. Transport the coal to the burner
B. Dry the coal
C. Ensure efficient burning of coal around the burner
D. Reduce primary air requirement
Question 376
Mixed gas' used in steel plants is a mixture of
A. B.F. gas and coke oven gas
B. Coke oven gas and converter gas
C. Coke oven gas and L.P.G
D. Blast furnace gas and naphtha vapor
Question 377
The calorific value of a gas of composition CO₂ = 20%, H₂ = 50%, CH₄ = 30%, is y. If the composition of gas is changed to H₂ = 50%, CH₄ = 30%, CO₂ = 10%, N₂ = 10%, then the calorifice value will be
A. Y
B. 0.95 y
C. 1.05 y
D. 1.8 y
Question 378
Blast furnace coke is made from coal by
A. Low temperature carbonisation
B. High temperature carbonisation
C. Medium temperature carbonisation
D. Heating the coal in an oven in presence of air
Question 379
Blast furnace gas constitutes mainly of
A. N₂ & CH₄
B. N₂ & H₂
C. N₂ & CO
D. CH₄ & CO₂
Question 380
The advantage of firing pulverised coal in the furnace lies in the fact, that it
A. Permits the use of high ash content coal
B. Permits the use of low fusion point ash coal
C. Accelerates the burning rate and economises on fuel combustion
D. All of the above
Question 381
Naphthalene is used for making
A. Insecticides (e.g. moth balls)
B. Unsaturated polyesters
C. Drug intermediates e.g. β-naphthol
D. All of the above
Question 382
Which of the following is not increased by using preheated combustion air in place of ordinary air at room temperature?
A. Calorific value of the fuel
B. Flame temperature achieved
C. Speed of combustion of fuel
D. Heat transfer rate to the stock in the furnace
Question 383
Coal is heated in absence of air for 7 minutes at a temperature of about __________ °C, during its volatile matter determination for proximate analysis.
A. 550
B. 750
C. 950
D. 1150
Question 384
Low temperature oxidation of coal resulting from bad storage conditions does not decrease its
A. Caking power
B. Calorific value
C. Hydrogen content
D. Oxygen content
Question 385
Bomb calorimeter can be used to determine the __________ of the coal.
A. Sulphur content
B. Calorific value
C. Both A & B
D. Neither A nor B
Question 386
Calorific values of both the solid as well as the liquid fuels can be determined by __________ calorimeter.
A. Bomb
B. Boy's
C. Junkar's
D. None of these
Question 387
Calorific value as determined by bomb calorimeter is the
A. Higher calorific value at constant volume
B. Gross calorific value at constant pressure
C. Lower calorific value at constant pressure
D. Net calorific value at constant volume
Question 388
Which of the following is the most poisonous gas?
A. Coke oven gas
B. Producer gas
C. Blast furnace gas
D. L.D. converter gas
Question 389
Efficient burning of anthracite coal requires
A. Low preheat of air
B. Fine grinding
C. High excess air
D. All of the above
Question 390
Washing of coal does not reduce its
A. S & P content
B. Heating value
C. Fusion point of ash
D. None of these
Question 391
Nitrogen in coal
A. Is present upto 1-2%
B. Comes from protein in parent vegetable matter
C. Is recovered as ammonia during its carbonisation
D. All of the above
Question 392
Oxygen required for theoretically complete combustion of 1 Nm³ methane is __________ Nm³.
A. 2
B. 4
C. 6
D. 1
Question 393
A liquid/gaseous fuel containing hydrocarbons and high amount of sulphur is burnt with 40% excess air. The flue gas still contains large amount of carbon monoxide. This may be due to the
A. Presence of large quantity of hydrogen in the fuel
B. Low calorific value of the fuel
C. High sulphur content in the fuel
D. Lack of thorough mixing of fuel with air
Question 394
Coking time in narrow by-product coke ovens is around __________ hours.
A. 18
B. 48
C. 8
D. 80
Question 395
A travelling grate stoker is meant for the efficient burning of __________ coal.
A. Caking
B. Pulverised
C. Non-caking
D. High ash
Question 396
A coal having higher volatile matter content will necessarily have lower
A. Ash fusion temperature
B. Calorific value
C. Ignition temperature
D. Caking index
Question 397
The gasification reaction represented by, C + H₂O = CO + H₂, is
A. Exothermic
B. Endothermic
C. Catalytic
D. Autocatalytic
Question 398
The lowest temperature, at which a solid fuel produces enough vapors to support continuous combustion, is called
A. Fire point
B. Smoke point
C. Burning temperature
D. Kindling temperature
Question 399
Atomising steam to fuel oil ratio in a burner should be around
A. 0.5
B. 1.5
C. 2.5
D. 3.5
Question 400
Volumetric ratio of N₂ to O₂ in dry atmospheric air is
A. 0.21
B. 3.76
C. 4.76
D. 0.79
Question 401
Combustion of pulverised coal compared to the lumpy coal
A. Provides better control of furnace temperature
B. Facilitates combustion with lower excess air
C. Provides higher thermal efficiency & flame temperature
D. All of the above
Question 402
Use of pulverised coal in boiler furnace provides
A. High calorific value
B. Better combustion
C. Smokeless burning
D. Less erosion on furnace walls
Question 403
The difference between total carbon and fixed carbon of coal will be minimum in case of
A. Lignite
B. Bituminous coal
C. Anthracite
D. High temperature coke (V.M < 0.5%)
Question 404
With increase in the oxygen content of the coal, its __________ decreases.
A. Calorific value
B. Caking power
C. Both A & B
D. Neither A nor B
Question 405
Gobar gas constitutes mainly of
A. CH₄ & CO₂
B. CO & CO₂
C. CH₄ & N₂
D. CO & N₂
Question 406
Producer gas comprises mainly of
A. CO & N₂
B. CO & H₂
C. CO₂ & N₂
D. CO₂ & H₂
Question 407
Flue gas from the heating chamber of byproduct coke ovens is removed by
A. Forced draft fan
B. Induced draft fan
C. Steam ejector
D. Natural draft
Question 408
Furnace oil consumption in a furnace for a given duty employing preheated combination air (at 300° ) may be reduced by about __________ percent as compared to the use of atmospheric combustion air.
A. 5
B. 10
C. 20
D. 35
Question 409
Removal of hydrogen from coke oven gas
A. Increases its calorific value
B. Decreases its calorific value
C. Does not alter its calorific value
D. Is not possible on commerical scale
Question 410
A coal that softens and fuses on heating is
A. Classified
B. Carbonised
C. Caking
D. Non-caking
Question 411
Coke having higher porosity has
A. Lower bulk density
B. Lower strength
C. Higher reactivity
D. All of the above
Question 412
Critical Air Blast (CAB) value of coke is a direct measure of its
A. Reactivity
B. Hardness
C. Strength
D. None of these
Question 413
A coal having high ratio of volatile matter to fixed carbon as compared to a coal having low ratio of volatile matter to fixed carbon
A. Is less liable to spontaneous combustion on storage
B. Is more difficult to ignite and produces a shorter flame
C. Requires smaller combustion space and less secondary air
D. None of these
Question 414
The maximum percentage of CO₂ in a flue gas (from a carbonaceous fuel) can be
A. 21
B. 77
C. 79
D. 29
Question 415
Net calorific value is the gross calorific value less the __________ heat of water in the product of combustion when cooled to 15°C.
A. Sensible
B. Latent
C. Sensible and latent
D. None of these
Question 416
Improper storage condition results in the weathering of coal and spontaneous combustion, which increases its
A. Caking index
B. Yield of carbonised products
C. Friability & oxygen content
D. Calorific value
Question 417
Higher percentage of ash in coal meant for the production of metallurgical grade coke
A. Decreases the hardness of coke
B. Decreases the abrasion resistance of coke
C. Causes brittleness in steel
D. None of these
Question 418
Coals used for the generation of producer gas should have
A. High caking index
B. Low fusion point of ash
C. High volatile matter content
D. Very low ash content (8-10%)
Question 419
The optimum percentage of excess air for combustion depends upon the __________ of the fuel.
A. Type (solid, liquid or gaseous)
B. Calorific value
C. Sulphur content
D. Ignition temperature
Question 420
Commercial production of petrol from coal (as practised in a factory at Sasol in South Africa) is done by the __________ of coal.
A. Hydrogenation
B. Gasification
C. Carbonisation
D. None of these
Question 421
Largest constituent of coke oven gas is
A. N₂
B. H₂
C. CH₄
D. CO₂
Question 422
A carbonaceous fuel (containing no H₂ or hydrocarbons) is burnt and the resulting flue gas contains 21% CO₂. It means that
A. 21% excess air has been used for combustion
B. 21% excess oxygen has been used for combustion
C. Complete combustion of fuel has taken place
D. No excess air has been used for combustion
Question 423
Coal is heated in presence of air to a temperature of about __________ °C, while determining its ash content for proximate analysis.
A. 500
B. 750
C. 950
D. 1100
Question 424
During its calorific value determination by bomb calorimeter, coal is combusted by
A. Air
B. Oxygen
C. Oxygen enriched air
D. None of these
Question 425
Orsat apparatus
A. Gives flue gas analysis on dry basis
B. Determines N₂ in flue gas indirectly
C. Can
D. All of the above
Question 426
Orsat apparatus is meant for
A. Gravimetric analysis of flue gas
B. Finding out combustion efficiency
C. Direct determination of nitrogen in flue gas by absorbing it in ammoniacal cuprous chloride
D. None of these
Question 427
Fat coals' are those coals which have very high
A. Caking capacity
B. Volatile matter content
C. Fusion point of its ash
D. Inherent moisture content
Question 428
__________ has the widest inflammability limit (explosion limit) of all the gases.
A. Hydrogen
B. Carbon monoxide
C. Acetylene
D. Methane
Question 429
Presence of force moisture in coal is most disadvantageous during its
A. Transportation and handling
B. Washing
C. Pulverisation
D. Storage
Question 430
Producer gas containing least amount of tar is produced by the
A. Partial combustion of coal
B. Partial combustion of large size (< 50 mm) coke
C. High pressure gasification of coal (e.g. in Lurgi gasifier)
D. Atmospheric pressure gasification of coal (e.g., in Kopper-Totzek gasifier)
Question 431
Coke oven gas constitutes mainly of
A. H₂ & CO
B. H₂ & CH₄
C. CH₄ & CO
D. H₂ & CO₂
Question 432
Which of the following is a poisonous fuel gas?
A. Coke oven gas
B. Blast furnace gas
C. Natural gas
D. None of these
Question 433
In flue gas analysis by Orsat's apparatus, oxygen is absorbed by
A. Potassium hydroxide
B. Cuprous chloride
C. Alkaline pyragllol solution
D. None of these
Question 434
Calorific value of pitch creosote mixture (PCM) i.e., C.T.F.-200 is about
A. 8800 kcal/m³
B. 8800 kcal/kg
C. Same as that of coal middling
D. 25000 kcal/kg
Question 435
Pick out the wrong statement.:
A. Carburetted water gas is also called blue gas
B. Coals are divided in four species according to their carbon content in Seylor's classification
C. Carbonisation time in a by-product coke oven is about 16 hours
D. Gross and net calorific value of a fuel is the same, if it does not contain hydrogen or hydrocarbons
Question 436
Pick the odd man out.
A. Briquettes
B. Wood
C. Oil gas
D. Pitch creosote mixture
Question 437
Coke oven gas after passing through return electrostatic tar precipitator (RETP) is used for the
A. Hot scarfing of steel slabs
B. Mixing with blast furnace gas
C. Coke oven battery heating
D. Steel ladle drying
Question 438
Bunsen burner is an example of a/an __________ burner.
A. Inside mixing/premix type
B. Outside mixing/diffusion flame/nozzle mix type
C. Rotary cup
D. Submerged combustion
Question 439
Stack (chimney) height in a big thermal power plant is dictated by the
A. Pollution control aspect
B. Draught to be created
C. Limitation of constructional facilities
D. None of these
Question 440
Undercharging of coal in the by-product coke ovens results in
A. Decrease in the c.v. of coke oven gas
B. Increase in its throughput
C. Increase in the c.v. of coke oven gas
D. No change in the c.v. of coke oven gas
Question 441
Which of the following will be unsuitable for dust cleaning from flue gas at 400°C from a pulverised coal fired boiler ?
A. Multicyclones
B. Bag filter
C. Wet scrubber
D. Hydrocyclones
Question 442
Calorific value of tar is about __________ Kcal/kg.
A. 8800
B. 12000
C. 5000
D. 16000
Question 443
Of the total tar present in raw coke oven gas, the tar recovered in primary cooler is about __________ percent.
A. 5
B. 25
C. 55
D. 75
Question 444
Which of the following is used for making the explosive 'TNT'?
A. Benzol
B. Toluene
C. Pyridine
D. Cerosote
Question 445
Wind loss' resulting from unscientific storage of coal may be the order of about __________ percent.
A. 2.5
B. 7.5
C. 10.5
D. 14.5
Question 446
Main use of hard coke produced by high temperature carbonisation is in the
A. Iron blast furnace
B. Cupola in foundaries
C. Sinter making
D. Domestic ovens
Question 447
Light oil whose major component is benzol, is obtained by the distillation of crude tar in the temperature range of __________ °C.
A. 80-170
B. 200-300
C. 250-270
D. 280-300
Question 448
In high temperature carbonisation (as compared to low temperature carbonisation) of coal, the
A. Gas yield is less
B. Tar yield is more
C. Ignition temperature of coke produced is less
D. Aromatic content of tar produced is more
Question 449
Which of the following is a single stage, fixed bed high pressure coal gasification process?
A. Winkler process
B. Kopper-Totzek process
C. Lurgi Process
D. None of these
Question 450
Width of the coke oven towards coke side is slightly more than that on pusher side to
A. Facilitate easy discharging of coke as it swells during carbonisation
B. Facilitate uniform heating of the oven
C. Increase the output of the coke
D. None of these
Question 451
Naphthalene recovered from coke oven gas is used
A. As moisture proof coating on fibres
B. As moth balls (insecticides)
C. As a fuel in furnaces
D. For making electrodes
Question 452
One kg of carbon for theoretically complete combustion requires __________ kg of air.
A. 11.5
B. 0.5
C. 23
D. 12
Question 453
Stoichiometric combustion of 12 kg of carbon requires __________ of oxygen.
A. 1kg mole
B. 22.4 Nm³
C. 32 kg
D. All of the above
Question 454
Main component of sewage gas produced during aneorobic decomposition of organic waste (by suitable bacteria) during sewage disposal is
A. H₂
B. CH₄
C. CO₂
D. N₂
Question 455
Insitu theory and drift theory are related to the
A. Origin of petroleum oil
B. Origin of coal
C. Coalification
D. Variation of coal quality with depth
Question 456
During the carbonisation of coal
A. All tar is evolved at < 600°C
B. Evolution of H₂ and formation of methane and aromatics occur at > 700°C
C. Hard semi-coke starts shrinking at 600°C
D. All of the above
Question 457
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 these
Question 458
Which of the following is not a micro component present in coal?
A. Micrinite
B. Clarain
C. Fusinite
D. Liptinite
Question 459
Narrow coke ovens as compared to wider coke ovens
A. Produce smaller coke
B. Produce stronger coke
C. Require less time of carbonisation
D. All of the above
Question 460
With increases in carbonisation temperature
A. Coke even gas yield increases
B. Tar yield increases
C. Hydrogen percentage in the coke oven gas decreases
D. Methane percentage in the coke oven gas increases
Question 461
Coke ovens in steel plant are heated by
A. Electricity
B. Coke oven gas
C. Mixed gas
D. Both B & C
Question 462
Which of the following has the highest flame velocity?
A. H₂
B. CO
C. CH₄
D. C₂H₆
Question 463
Which of the following gaseous fuels has the lowest calorific value?
A. Gobar gas
B. Refinery gas
C. Converter gas
D. Blast furnace gas
Question 464
As the C/H ratio of the fuel increases, the amount of CO₂ formed on combustion __________ for the same percentage of excess air.
A. Decreases
B. Increases
C. Remains same
D. May increase or decrease depending on the type of fuel
Question 465
Which of the following would require least amount of secondary air for combustion?
A. Coke breeze containing 25% ash and 2% volatile matter
B. Anthracite containing 10% volatile matter and 8% ash
C. Bituminous coal containing 20% ash and 25% volatile matter
D. Semi-bituminous coal containing 25% ash and 20% volatile matter
Question 466
The function of secondary combustion air is to
A. Pneumatically convey the pulverised coal
B. Completely burn the volatile matter
C. Burn the lumpy coal
D. None of these
Question 467
KOH solution used in orsat apparatus absorbs
A. CO₂
B. SO₂
C. Both A & B
D. Neither A nor B
Question 468
When the coal is heated in absence of air, it is called its
A. Deoxidation
B. Gasification
C. Coalification
D. Carbonisation
Question 469
During combustion of gaseous fuels, deficiency of air
A. Lengthens the flame
B. Tends to shorten the flame
C. Does not affect the flame length
D. Increases the flame temperature
Question 470
Soft coke is not
A. Produced by low temperature carbonisation of coal
B. A domestic fuel
C. Used in blast furnaces
D. None of these
Question 471
Tar yield in the low temperature and high temperature carbonisation of dry coal may be respectively __________ percent.
A. 3 & 10
B. 10 & 3
C. 10 & 20
D. 15 & 8
Question 472
Presence of phosphorous in metallurgical coal
A. Is not undersirable
B. Reduces its calorific value
C. Badly affects the quality of steel
D. Increases its caking power
Question 473
Short/intense flame is produced during combustion of gaseous fuel by using
A. High amount/current of combustion air
B. Low amount/current of combustion air
C. Preheated secondary air
D. Very little excess air
Question 474
Sulphur in metallurgical coal
A. Contributes to its heating value
B. Affects the quality of steel produced as cracks develop on the surface while rolling the steel
C. Both A and B
D. Neither A nor B
Question 475
Nitrogen present in the flue gas is determined in the orsat apparatus by absorbing it in
A. KOH
B. Ammoniacal cuprous chloride
C. Pyrogallol solution
D. None of these
Question 476
If CO₂ is not fully absorbed by the KOH solution meant for its absorption in the orsat apparatus, it will appear as
A. O₂
B. CO
C. N₂
D. SO₂
Question 477
Which of the following has the highest calorific value (kcal/Nm³) ?
A. Carburetted water gas
B. Gobar gas
C. Natural gas
D. LPG
Question 478
Which of the following has the least calorific value (kcal/Nm³) ?
A. Blast furnace gas
B. Coke oven gas
C. Sewage gas
D. Natural gas
Question 479
Caking index of coal blend used for blast furnace coke making is about
A. 8
B. 12
C. 22
D. 36
Question 480
Purity of coke means that, it is high in carbon and low in
A. Volatiles
B. Ash
C. Iron
D. Moisture
Question 481
Temperature of preheated air used for the transportation of pulverised coal through pipes to the burner of a boiler furnace is restricted to a maximum limit of about 300° C to avoid the
A. Requirement of large volume combustion chamber
B. Risk of explosion
C. Chances of clinker formation
D. Incomplete combustion of coal
Question 482
A coal containing high amount of volatile matter will have
A. Low ignition temperature
B. Very little ash content
C. High fusion point of its ash
D. Low adiabatic flame temperature
Question 483
The bright glow of a combustion process is the characteristic of __________ temperature oxidation of coal.
A. Fast & high
B. Slow & low
C. Slow & high
D. Fast & slow
Question 484
A fuel with high heat release rate will
A. Require smaller combustion chamber
B. Have high calorific value
C. Have high adiabatic flame temperature
D. None of these
Question 485
Out of the following, which is the most important parameter for the blast furnace grade coke?
A. CSR & CRI
B. Ash content
C. Moisture content
D. Volatile matter content
Question 486
The hottest part of the flame lies in its____zone.
A. Non-luminous
B. Luminous
C. Yellow
D. Unburnt gases
Question 487
The fuel ratio of a coal is
A. The ratio of its percentage of fixed carbon to that of volatile matter
B. Helpful in estimation of its rank
C. Both A and B
D. Neither A nor B
Question 488
The weathering index of a coal
A. Gives an idea of the fusion temperature of ash
B. Is related to its calorific value
C. Is a measure of its size stability, when stored & exposed to weather
D. Is a measure of its caking tendency
Question 489
Hardgrove grindability index of four coal samples are given below. Which of them is the easiest to grind?
A. 50
B. 70
C. 85
D. 100
Question 490
Ionisation potential applied across the electrodes of electrostatic tar precipitator is around
A. 230 V AC
B. 60 KV AC
C. 230 V DC
D. 60 KV DC
Question 491
A coal having higher volatile matter content, has lower
A. Smoking tendency on burning
B. Coke oven gas yield on carbonisation
C. Chance of catching fire during storage in open space
D. Ignition temperature
Question 492
Which of the following fertilisers is produced in the by-products recovery (from coke oven gas) plant attached to an integrated steel plant?
A. Ammonium sulphate
B. Ammonium nitrate
C. Ammonium phosphate
D. None of these
Question 493
Gross calorific value will be equal to the net calorific value for
A. H₂
B. C₂H₂
C. CO
D. C₂H₆
Question 494
Power alcohol as compared to straight run gasoline has lower
A. Calorific value
B. Octane number
C. Specific gravity
D. Viscosity
Question 495
Which of the following petrographic constituents of coal is non-coking?
A. Vitrain
B. Clarain
C. Durain
D. Fussain
Question 496
Moisture loss is determined by the
A. Humidity of combustion air
B. Moisture content of fuel
C. Both A and B
D. The water formed by combustion reaction
Question 497
Main constituent of the gas produced from a gobar gas plant is
A. CO₂
B. CH₄
C. H₂
D. CO
Question 498
Which is the heaviest fuel gas out of the following?
A. Blast furnace gas
B. Coke oven gas
C. Water gas
D. Carburetted water gas
Question 499
Coal tar fuels (CTF) as compared to petroleum based fuel oils have higher
A. Calorific value
B. Higher C/H ratio
C. Sulphur content
D. Difference in gross & net calorific value
Question 500
By-products recovery process from coal carbonisation is termed as direct, indirect and semi direct process depending upon the method of recovery of
A. Tar
B. Benzol
C. Ammonia
D. None of these
Question 501
In low temperature carbonisation of coal, the
A. Yield of coke oven gas is 290 Nm³ /ton dry coal
B. Volatile matter in coke is zero
C. Temperature maintained is 700°C
D. Yield of tar is about 3% of dry coal
Question 502
Which of the following is not a by-product recovered in a high temperature coal carbonisation plant?
A. Benzol
B. Pitch-cresosote mixture (PCM)
C. Napthalene
D. Ethylene
Question 503
Softening temperature of coal ash is a measure of the __________ of coal.
A. Caking tendency
B. Coking tendency
C. Clinkering tendency
D. Size stability
Question 504
Lurgi coal gasifier is a pressurised __________ bed reactor.
A. Moving
B. Fixed
C. Fluidised
D. Entrained
Question 505
Which of the following fuels is the best for burning on chain grate stoker?
A. Non-caking coal
B. Caking coal
C. Coking coal
D. Pulverised coal
Question 506
In Orsat's apparatus, ammoniacal cuprous chloride is used for selectivity absorbing
A. CO
B. CO₂
C. O₂
D. H₂O
Question 507
A gaseous fuel in order to develop luminousity on burning, must contain
A. Carbon monoxide
B. Hydrocarbons
C. Hydrogen
D. Oxygen
Question 508
Presence of nitrogen in combustion air does not reduce the
A. Amount of heat liberated
B. Flame temperature
C. Flue gas temperature
D. Any of the above
Question 509
Air/gas ratio for complete combustion will be the highest for
A. LPG
B. Gobar gas
C. Coke oven gas
D. Carburetted water gas
Question 510
Bomb calorimeter is used for the determination of calorific value of the __________ fuels.
A. Gaseous
B. Solid
C. Liquid
D. Both B and C
Question 511
Which of the following coal gasification processes will produce gas having maximum methane content?
A. Winkler process
B. Lurgi process
C. Kopper-Totzek process
D. All of the above
Question 512
Oxygen content in a flue gas was found to be 4%. It implies that excess air used for combustion was around __________ percent.
A. 4
B. 96
C. 20
D. 40
Question 513
Washing of coal
A. Reduces its sulphur and ash content
B. Controls its ash fusibility and increases its calorific value
C. Improves its coking properties
D. All of the above
Question 514
Washing of coal
A. Reduces its ash & sulphur content
B. Improves its coking properties
C. Increase the fusion point of its ash by removing chlorine compounds
D. All of the above
Question 515
Washing of coal decreases its
A. Caking index
B. Mineral matter content
C. Ash content
D. Both B and C
Question 516
For which pair of the fuel gases, calorific value (C.V.) of one fuel is almost double that of the other on volume basis (i.e., kcal/Nm³ ), while the C.V. is same on weight basis (i.e., kcal/kg) ?
A. Propane and acetylene
B. Propane and LPG
C. Sewage gas and gobar gas
D. B.F. gas and coke oven gas
Question 517
Which of the following accentuates clinker-ing trouble on furnace grate burning coal?
A. Low reactivity of carbonised residue containing high proportions of iron & sulphur
B. Low forced draught and fuel bed temperature
C. Thick fire bed and preheated primary air
D. All of the above
Question 518
High temperature in gasification of coal favours
A. High production of CO₂
B. Low production of CO₂
C. High production of CO
D. Both B and C
Question 519
Which of the following oil gasification processes is non-catalytic?
A. Semet-Solvay process
B. Segas process
C. Onia-Gegi process
D. Steam reforming of naphtha