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Fuels and Combustion MCQ Questions & Answers

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

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 2

Water gas constitutes mainly of

A. CO & H₂
B. CO & N₂
C. CO₂ & H₂
D. CH₄ & H₂

Question 3

High temperature carbonisation of coal takes place at __________ °C.

A. 2000
B. 600
C. 1100
D. 1600

Question 4

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 5

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 6

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 7

Coke oven gas consists mainly of

A. H2, & CH4
B. CO, & CO2
C. H2, & CO
D. CH4, & CO

Question 8

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 9

__________ has the widest inflammability limit (explosion limit) of all the gases.

A. Hydrogen
B. Carbon monoxide
C. Acetylene
D. Methane

Question 10

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 11

The gas which contributes maximum to the heating value of natural gas is

A. CO
B. CO₂
C. H₂
D. CH₄

Question 12

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 13

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 14

Gobar gas is produced by the __________ of 'gobar' (cow dung).

A. Hydrolysis
B. Fermentation
C. Oxidation
D. Dehydration

Question 15

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 16

Coke oven gas burns with an yellowish flame, because of the presence of

A. CO₂
B. CH₄
C. H₂
D. NH₃

Question 17

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 18

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 19

Laboratory gas is obtained by the cracking of

A. gasoline
B. diesel
C. fuel oil
D. kerosene

Question 20

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 21

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 22

Low temperature carbonisation of coal takes place at __________ °C.

A. 300
B. 1100
C. 700
D. 150

Question 23

A coal containing very high percentage of durain is called __________ coal.

A. bright
B. splint
C. non-banded
D. boghead

Question 24

Calorific value of a typical dry anthracite coal may be around __________ Kcal/kg.

A. 1000
B. 4000
C. 8000
D. 15000

Question 25

Washing of coal is done to reduce the

A. Inherent impurities
B. Adhering impurities
C. Mineral matter
D. Both B and C

Question 26

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 27

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 28

Which of the following has the highest heat of combustion?

A. H₂
B. CO
C. CH₄
D. C₂H₆

Question 29

Yield of pitch from distillation of high temperature tar is around __________ percent.

A. 10
B. 25
C. 65
D. 90

Question 30

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 31

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 32

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 33

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 34

Power alcohol as compared to straight run gasoline has lower

A. Calorific value
B. Octane number
C. Specific gravity
D. Viscosity

Question 35

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 36

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 37

When incomplete combustion loss is high, the flue gas analysis shows large amount of

A. CO₂
B. CO
C. O₂
D. C

Question 38

__________ 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 39

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 40

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 41

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 42

Which of the following is not a manufactured fuel ?

A. Furnace oil
B. Bagasse
C. Semi-coke
D. Kerosene

Question 43

A good quality coal should have

A. Low fusion point of ash
B. High ash content
C. High sulphur
D. None of these

Question 44

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 45

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 46

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 47

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 48

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 49

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 50

Coal tar (produced by high temperature carbonisation) is the main source of

A. Aromatic compounds
B. Alphatic compounds
C. Paraffins
D. Olefins

Question 51

Which of the following has the highest flame speed?

A. CO
B. H₂
C. CH₄
D. C₂H₆

Question 52

Coke having higher porosity has

A. Lower bulk density
B. Lower strength
C. Higher reactivity
D. All of the above

Question 53

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 54

Main use of soft coke is as __________ fuel.

A. Domestic
B. Blastfurnace
C. Foundary
D. None of these

Question 55

Ammonia content in raw coke oven gas is about __________ gm/Nm³.

A. 1
B. 15
C. 50
D. 100

Question 56

Which of the following is called "blue gas"?

A. Coke oven gas
B. Water gas
C. Natural gas
D. Producer gas

Question 57

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 58

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 59

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 60

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 61

Calorific value of furnace oil is about __________ Kcal/kg.

A. 10000
B. 15000
C. 5000
D. 20000

Question 62

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 63

Which of the following is not used as a binder in coal briquetting ?

A. Tar
B. Molasses
C. Pitch
D. Line

Question 64

Incomplete combustion of a fuel is characterised by the high __________ in the flue gas.

A. Smoke
B. Temperature
C. Oxygen
D. Carbon monoxide

Question 65

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 66

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 67

Caking index of coal blend used for blast furnace coke making is about

A. 8
B. 12
C. 22
D. 36

Question 68

The calorific value of producer gas is around __________ kcal/Nm³

A. 1300
B. 500
C. 4500
D. 9000

Question 69

Coking time in beehive coke oven is about

A. 12 hours
B. 2-3 days
C. One week
D. Two weeks

Question 70

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 71

When the coal is heated in absence of air, it is called its

A. Deoxidation
B. Gasification
C. Coalification
D. Carbonisation

Question 72

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 73

The calorific value of L.D. converter gas is about __________ Kcal/Nm³ .

A. 1800
B. 800
C. 4500
D. 10000

Question 74

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 75

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 76

A good metallurgical coke should have very low

A. Sulphur & phosphorous content
B. Porosity
C. Fusion point of its ash
D. Hardness & strength

Question 77

Efficient burning of anthracite coal requires

A. Low preheat of air
B. Fine grinding
C. High excess air
D. All of the above

Question 78

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 79

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 80

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 81

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 82

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 83

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 84

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 85

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 86

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 87

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 88

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 89

Calorific value of of blast furnace gas is around __________ KCal/Nm³.

A. 850
B. 1800
C. 4200
D. 6500

Question 90

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 91

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 92

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 93

The gas which contributes maximum to the heating value of natural gas is

A. CO
B. CO2
C. H2
D. CH4

Question 94

The hottest part of the flame lies in its____zone.

A. Non-luminous
B. Luminous
C. Yellow
D. Unburnt gases

Question 95

A coal with high __________ content, would ignite most easily.

A. Fixed carbon
B. Volatile matter
C. Ash
D. Oxygen

Question 96

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 97

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 98

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 99

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 100

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 101

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 102

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 103

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 104

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 105

KOH solution used in orsat apparatus absorbs

A. CO₂
B. SO₂
C. Both A & B
D. Neither A nor B

Question 106

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 107

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 108

Percentage of hydrogen in coke oven gas may be around

A. 10
B. 25
C. 45
D. 60

Question 109

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 110

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 111

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 112

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 113

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 114

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 115

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 116

Producer gas comprises mainly of

A. CO & N₂
B. CO & H₂
C. CO₂ & N₂
D. CO₂ & H₂

Question 117

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 118

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 119

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 120

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 121

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 122

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 123

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 124

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 125

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 126

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 127

Purity of coke means that, it is high in carbon and low in

A. Volatiles
B. Ash
C. Iron
D. Moisture

Question 128

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 129

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 130

Combustion reaction of fuels is a/an __________ reaction.

A. auto catalytic
B. exothermic
C. endothermic
D. none of these

Question 131

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 132

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 133

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 134

Percentage of nitrogen in blast furnace gas may be around

A. 5
B. 25
C. 55
D. 80

Question 135

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 136

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 137

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 138

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 139

Coking coals are invariably

A. Lignites
B. Bituminous coals
C. Semi-anthracites
D. Anthracites

Question 140

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 141

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 142

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 143

High pressure coal gasification is employed in __________ process.

A. Lurgi
B. Kopper-Totzek
C. Winkler
D. None of these

Question 144

Coke ovens in steel plant are heated by

A. Electricity
B. Coke oven gas
C. Mixed gas
D. Both B & C

Question 145

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 146

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 147

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 148

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 149

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

Question 150

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 151

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 152

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 153

The maximum percentage of CO₂ in a flue gas (from a carbonaceous fuel) can be

A. 21
B. 77
C. 79
D. 29

Question 154

Gross heating value of coal is __________ the net heating value.

A. Higher than
B. Lower than
C. Same as
D. None of these

Question 155

The cooling medium used in dry quenching of coke is

A. Nitrogen
B. Air
C. Phenolic water
D. Carbon dioxide

Question 156

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 157

Preheating of a gaseous fuel results in increased

A. Flame length
B. Flame temperature
C. Quantity of flue gas
D. Ignition temperature

Question 158

Which of the following is not a by-product fuel?

A. Pitch
B. Blast furnace gas
C. Petrol
D. Refinery gas

Question 159

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 160

Volumetric ratio of N₂ to O₂ in dry atmospheric air is

A. 0.21
B. 3.76
C. 4.76
D. 0.79

Question 161

Percentage of methane in coke oven gas may be around

A. 5
B. 15
C. 25
D. 50

Question 162

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 163

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 164

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 165

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 166

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 167

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 168

Largest constituent of coke oven gas is

A. N₂
B. H₂
C. CH₄
D. CO₂

Question 169

Bituminous coal

A. ignites less easily than anthracite.
B. is generally coking.
C. burns with smoky yellow flame.
D. both (b) and (c).

Question 170

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 171

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 172

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 173

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 174

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 175

Which of the following has the highest flame velocity?

A. H₂
B. CO
C. CH₄
D. C₂H₆

Question 176

Which of the following is not used as a binder in coal briquetting?

A. Tar
B. Molasses
C. Pitch
D. Line

Question 177

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 178

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 179

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 180

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 181

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 182

Which of the following is coking?

A. Vitrain
B. Fussain
C. Both A & B
D. Neither A nor B

Question 183

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 184

Main constituent of the gas produced from a gobar gas plant is

A. CO₂
B. CH₄
C. H₂
D. CO

Question 185

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 186

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 187

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 188

By-products are __________ recovered in 'Beehive ovens'.

A. Fully
B. Partially
C. Not at all
D. Negligibly

Question 189

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 190

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 191

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 192

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 193

Main constituents of purified Lurgi gas are

A. H₂, CmHn & CO₂
B. CO, H₂ & CH₄
C. CO₂, O₂ & CO
D. N₂, H₂ & CO₂

Question 194

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 195

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 196

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 197

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 198

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 199

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 200

One kg of carbon for theoretically complete combustion requires __________ kg of air.

A. 11.5
B. 0.5
C. 23
D. 12

Question 201

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 202

Which of the following is not a by-product fuel?

A. Sewage gas
B. Refinery gas
C. Producer gas
D. Bagasse

Question 203

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 204

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 205

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 206

__________ of the coal is the basis for Seylor's coal classification.

A. Proximate analysis
B. Ultimate analysis
C. Caking index
D. Calorific value

Question 207

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 208

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 209

Fuel for a fast breeder nuclear reactor is

A. Plutonium
B. Uranium
C. Radium
D. Neptunium

Question 210

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 211

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 212

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 213

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 214

Calorific value of coke oven gas is around __________ Kcal/Nm³.

A. 900
B. 4200
C. 7500
D. 2000

Question 215

__________ present in coal is not determined in its ultimate analysis.

A. Fixed carbon
B. Total carbon
C. Hydrogen
D. Nitrogen

Question 216

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 217

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 218

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 219

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 220

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 221

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 222

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 223

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 224

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 225

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 226

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 227

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 228

Oxygen percentage (by weight) in atmospheric air is

A. 19
B. 21
C. 23
D. 29

Question 229

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 230

Number of macrocomponents present in coal according to Stopes are

A. Four
B. Five
C. Six
D. Two

Question 231

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 232

Hard coke is manufactured from

A. Lignite
B. Bituminous coal
C. Semi-anthracite
D. Anthracite

Question 233

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 234

Most of the coking coals are

A. Anthracite
B. Bituminous
C. Lignite
D. None of these

Question 235

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 236

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 237

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 238

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 239

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 240

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 241

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 242

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 243

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 244

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 245

A gaseous fuel in order to develop luminousity on burning, must contain

A. Carbon monoxide
B. Hydrocarbons
C. Hydrogen
D. Oxygen

Question 246

Which of the following is a lean fuel gas?

A. Coke oven gas
B. LPG
C. Blast furnace gas
D. Natural gas

Question 247

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 248

Coking time in a commercial high temperature coal carbonisation plant is about __________ hours.

A. 6
B. 18
C. 28
D. 36

Question 249

Bituminous coal

A. Ignites less easily than anthracite
B. Is generally coking
C. Burns with smoky yellow flame
D. Both B and C

Question 250

Which of the following combustibles is absent in blast furnace gas?

A. H₂
B. CH₄
C. CO
D. None of these

Question 251

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 252

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 253

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 254

A coal that softens and fuses on heating is

A. Classified
B. Carbonised
C. Caking
D. Non-caking

Question 255

Hard pitch is used for making

A. Pulverised fuel
B. Perfumes
C. Insecticides
D. Plastics

Question 256

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 257

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 258

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 259

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 260

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 261

Oxygen required for theoretically complete combustion of 1 Nm³ methane is __________ Nm³.

A. 2
B. 4
C. 6
D. 1

Question 262

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 263

Gobar gas constitutes mainly of

A. CH₄ & CO₂
B. CO & CO₂
C. CH₄ & N₂
D. CO & N₂

Question 264

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 265

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 266

Quantity of coke produced from metallurgical coal may be around __________ percent.

A. 30
B. 50
C. 75
D. 95

Question 267

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 268

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 269

Coking time in narrow by-product coke ovens is around __________ hours.

A. 18
B. 48
C. 8
D. 80

Question 270

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 271

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 272

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 273

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 274

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 275

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 276

When incomplete combustion loss is high, the flue gas analysis shows large amount of

A. CO2
B. CO
C. O2
D. C

Question 277

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 278

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 279

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 280

Calorific value of bituminous coal may be around __________ Kcal/kg.

A. 500
B. 1500
C. 6500
D. 20000

Question 281

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 282

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 283

Presence of force moisture in coal is most disadvantageous during its

A. Transportation and handling
B. Washing
C. Pulverisation
D. Storage

Question 284

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 285

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 286

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 287

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 288

High excess air in combustion of fuels results in

A. Increased fuel consumption
B. Incomplete combustion
C. Smoky flame
D. None of these

Question 289

Gross calorific value will be equal to the net calorific value for

A. H₂
B. C₂H₂
C. CO
D. C₂H₆

Question 290

Tolerable concentration of toxic carbon monoxide in atmospheric air is about __________ PPm.

A. 50
B. 1000
C. 5000
D. 10000

Question 291

__________ process is meant for direct hydrogenation of coal to produce liquid fuel.

A. Fischer-Tropsch
B. Bergius
C. Lurgi
D. None of these

Question 292

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 293

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 294

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 295

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 296

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 297

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 298

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 299

Washing of coal does not reduce its

A. S & P content
B. Heating value
C. Fusion point of ash
D. None of these

Question 300

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 301

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 302

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 303

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 304

Catalyst used in Fischer-Tropsch process is

A. Nickel
B. Zinc oxide
C. Alumina
D. Thorium oxide

Question 305

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 306

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 307

Calorific value of tar is about __________ Kcal/kg.

A. 8800
B. 12000
C. 5000
D. 16000

Question 308

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 309

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 310

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 311

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 312

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 313

Yield of blast furnace gas is about __________ Nm³ /ton of pig iron.

A. 300
B. 2000
C. 5000
D. 10000

Question 314

The most matured coal out of the following is

A. Lignite
B. Semi-anthracite
C. Sub-bituminous
D. Bituminous

Question 315

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 316

Main constituent of natural gas is

A. CH₄ (upto 90%)
B. C₂H₆
C. C₃H₈
D. H₂

Question 317

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 318

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 319

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 320

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 321

Caking index of a coal is a measure of its

A. Abradability
B. Reactivity
C. Agglutinating (binding) properties
D. Porosity

Question 322

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 323

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 324

Volatile matter content of metallurgical coke may be around __________ percent.

A. 1-2
B. 10-15
C. 22-26
D. 30-33

Question 325

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 326

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 327

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 328

Which is the most matured coal?

A. Lignite
B. Bituminous
C. Semi-anthracite
D. Anthracite

Question 329

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 330

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 331

Which of the following petrographic constituents of coal is non-coking?

A. Vitrain
B. Clarain
C. Durain
D. Fussain

Question 332

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 333

Which of the following is not endothermic?

A. Cracking
B. Reforming
C. Gasification
D. Partial oxidation

Question 334

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 335

Caking coal is desirable for

A. Burning on travelling grate
B. Coke making
C. Burning on firebars
D. All of the above

Question 336

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 337

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 338

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 339

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 340

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 341

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 342

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 343

Washing of coal decreases its

A. Caking index
B. Mineral matter content
C. Ash content
D. Both B and C

Question 344

Which of the following is not a micro component present in coal?

A. Micrinite
B. Clarain
C. Fusinite
D. Liptinite

Question 345

Which of the following has the highest calorific value?

A. Lignite
B. Sub-bituminous coal
C. Anthracite
D. Peat

Question 346

Gobar gas is produced by the __________ of cown dung.

A. Fermentation
B. Oxidation
C. Hydrogenation
D. None of these

Question 347

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 348

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 349

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 350

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 351

In Orsat's apparatus, ammoniacal cuprous chloride is used for selectivity absorbing

A. CO
B. CO₂
C. O₂
D. H₂O

Question 352

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 353

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 354

Abrasion index of blast furnace coke should be around __________ percent.

A. 20
B. 35
C. 55
D. 80

Question 355

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 356

Wobbe index' is a characteristic of

A. Solid fuels
B. Gaseous fuels
C. Liquid fuels
D. Fat coals

Question 357

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 358

High sulphur (4-6%) coal in India are found in

A. Assam
B. Andhra Pradesh
C. Bengal
D. Madhya Pradesh

Question 359

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 360

Cannel coal and boghead coal are the examples of

A. Humic coals
B. Liptobiolites
C. Sapropelic coals
D. None of these

Question 361

Calorific value of wood gas is about __________ kcal/Nm³.

A. 1500
B. 3300
C. 5400
D. 8500

Question 362

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 363

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 364

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 365

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 366

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 367

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 368

Blast furnace gas is a very poisonous gas because of its predominantly high __________ content.

A. H₂O
B. CO₂
C. CO
D. CH₄

Question 369

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 370

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 371

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 372

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 373

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 374

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 375

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 376

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 377

Carbon Content by weight in air dried wood may be about __________ percent.

A. 10
B. 25
C. 50
D. 80

Question 378

Shatter index of the coke is a measure of its

A. Strength
B. Bulk density
C. Reactivity
D. None of these

Question 379

The gasification reaction represented by, C + H₂O = CO + H₂, is

A. Exothermic
B. Endothermic
C. Catalytic
D. Autocatalytic

Question 380

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 381

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 382

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 383

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 384

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 385

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 386

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 387

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 388

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 389

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 390

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 391

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 392

Pensky-Marten apparatus is used for those oils, whose flash points are __________ °F.

A. <120
B. >120
C. <90
D. 90-110

Question 393

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 394

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 395

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 396

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 397

Largest constituent of blast furnace gas is

A. N₂
B. CO
C. CO₂
D. H₂

Question 398

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 399

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 400

Which of the following has the highest theoretical flame temperature ?

A. Blast furnace gas
B. Hydrogen
C. Acetylene
D. Coke oven gas

Question 401

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 402

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 403

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 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

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 406

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 407

Abel apparatus is used for those oils, whose flash points are___°F.

A. <120
B. >120
C. >280
D. 300-600

Question 408

Size of blast furnace grade coke is __________ mm.

A. 25-80
B. 0-15
C. 15-25
D. >100

Question 409

(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 410

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 411

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 412

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 413

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 414

Volatile matter content in coking coal may be about __________ percent.

A. 1
B. 7
C. 22
D. 46

Question 415

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 416

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 417

Presence of __________ in a dry gaseous fuel does not contribute to its calorific value.

A. sulphur
B. oxygen
C. hydrogen
D. carbon

Question 418

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 419

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 420

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 421

About __________ Nm³ of air will be required for the complete combustion of 2Nm³ of CO.

A. 2
B. 3
C. 5
D. 1

Question 422

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 423

Dry air required to burn 1 kg of carbon completely may be around __________ kg.

A. 11
B. 2
C. 20
D. 38

Question 424

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 425

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 426

Highly reactive coke have lower

A. Porosity
B. Coke reactivity index (CRI)
C. Critical air blast (CAB) value
D. Both B and C

Question 427

(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 428

Yield of charcoal in high temperature carbonisation of wood is about __________ percent.

A. 10
B. 25
C. 50
D. 75

Question 429

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 430

Which of the following is not a 'manufactured' fuel?

A. LPG
B. Coal briquettes
C. Tar
D. Colloidal fuels

Question 431

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 432

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 433

Bulk density of pulverised coal may be about __________ kg/m³.

A. 100
B. 500
C. 1000
D. 1500

Question 434

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 435

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 436

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 437

During coking of coal, the ash content (percentage)

A. Increases
B. Decreases
C. Remains constant
D. None of these

Question 438

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 439

__________ is used as jet engine fuel.

A. Petrol
B. Diesel
C. Kerosene
D. LPG

Question 440

The main product of high temperature carbonisation of coal is

A. Coke
B. Ammonia
C. Tar
D. Coke oven gas

Question 441

Main constituents of benzol are

A. Benzene, toluene & xylene
B. Tar & creosote
C. Ammonia & phenol
D. Anthracene & phenol

Question 442

Coke oven gas constitutes mainly of

A. H₂ & CO
B. H₂ & CH₄
C. CH₄ & CO
D. H₂ & CO₂

Question 443

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 444

Lurgi coal gasifier is a pressurised __________ bed reactor.

A. Moving
B. Fixed
C. Fluidised
D. Entrained

Question 445

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 446

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 447

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 448

Blast furnace gas burns with a bluish flame, because of the presence of

A. CO
B. CH₄
C. CO₂
D. S

Question 449

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 450

Blast furnace gas constitutes mainly of

A. N₂ & CH₄
B. N₂ & H₂
C. N₂ & CO
D. CH₄ & CO₂

Question 451

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 452

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 453

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 454

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 455

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 456

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 457

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 458

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 459

Calorific value of dry wood may be around __________ Kcal/kg.

A. 5
B. 50
C. 500
D. 5000

Question 460

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 461

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 462

A good coking coal should have high __________ content.

A. Ash
B. Sulphur & phosphorus
C. Moisture
D. None of these

Question 463

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 464

Gas yield in the Kopper-Totzek coal gasifier is about __________ Nm³/ton coal (ash = 35%).

A. 150
B. 1500
C. 3500
D. 5000

Question 465

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 466

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 467

Which of the following is used for making the explosive 'TNT' ?

A. Benzol
B. Toluene
C. Pyridine
D. Cerosote

Question 468

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 469

Which of the following is not a binder for coal briquetting?

A. Coal tar
B. Bitumen
C. Molasses
D. None of these

Question 470

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 471

C/H ratio is the maximum in case of

A. Coal
B. Furnace oil
C. Natural gas
D. Naphtha

Question 472

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 473

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 474

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 475

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 476

Percentage of carbon monoxide in blast furnace gas may be around

A. 8
B. 14
C. 22
D. 52

Question 477

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 478

Which of the following is a primary fuel?

A. Blast furnace coke
B. Gasoline
C. Natural gas
D. Wood charcoal

Question 479

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 480

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 481

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 482

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 483

'Wobbe index' is a characteristic of

A. solid fuels
B. gaseous fuels
C. liquid fuels
D. fat coals

Question 484

Micum Index of a coke is a measure of its

A. Reactivity
B. Porosity
C. Bulk density
D. Hardness & strength

Question 485

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 486

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 487

Which of the following is used for making the explosive 'TNT'?

A. Benzol
B. Toluene
C. Pyridine
D. Cerosote

Question 488

Coal containing large quantity of __________ are difficult to wash.

A. Ash
B. Inherent mineral matter
C. Free impurities
D. Volatile matter

Question 489

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 490

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 491

Which of the following coke has the least percentage of ash?

A. Petroleum coke
B. Beehive coke
C. Foundary coke
D. Metallurgical coke

Question 492

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 493

Fat' coal means a coal having

A. Low calorific value
B. High volatile matter
C. Low ash content
D. Non smoking tendency

Question 494

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 495

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 496

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 497

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 498

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 499

Pick the odd man out.

A. Briquettes
B. Wood
C. Oil gas
D. Pitch creosote mixture

Question 500

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 501

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 502

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 503

Which of the following has the highest calorific value (kcal/Nm³) ?

A. Carburetted water gas
B. Gobar gas
C. Natural gas
D. LPG

Question 504

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 505

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 506

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 507

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 508

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 509

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 510

A travelling grate stoker is meant for the efficient burning of __________ coal.

A. Caking
B. Pulverised
C. Non-caking
D. High ash

Question 511

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 512

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 513

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 514

The calorific value of natural gas is about __________ kcal/Nm³.

A. 10, 000
B. 2500
C. 25, 000
D. 35, 000

Question 515

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 516

Assam coals suffers mainly from the disadvantage of high __________ content.

A. Ash
B. Volatile matter
C. Sulphur (4-6%)
D. Moisture

Question 517

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 518

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 519

Critical Air Blast (CAB) value of coke is a direct measure of its

A. Reactivity
B. Hardness
C. Strength
D. None of these

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