A coal with high ash content

has low quantity of mineral matter.

As time passes, the calorific value of stored coal

may increase or decrease (depends on the method of storage).

Use of excess of combustion air in the combustion of fuels results in

condensation of water vapour from the fuel gas.

Low temperature oxidation of stored coal results in the

decrease in its caking power & calorific value.

decrease in its carbon & hydrogen content.

increase in its oxygen content.

The fuel ratio of a coal is

the ratio of its percentage of fixed carbon to that of volatile matter.

helpful in estimation of its rank.

a black banded coal which burns with a non-smoky yellowish flame.

can be used for gasification and steam generation.

a black banded coal which burns with a non-smoky yellowish flame.

Advantages of fluidised bed combustion are

reduced NOx formation in flue gas.

lower furnace operating temperature.

The main advantage of forced draft over natural draft is that

combustion of fuel is complete.

smaller height chimney can be used.

High ash containing coke

has poor strength and abrasion resistance.

produces more slag when used in the blast furnace.

has poor strength and abrasion resistance.

is desirable in producer gas manufacture.

'Mixed gas' used in steel plants is a mixture of

coke oven gas and converter gas.

blast furnace gas and naphtha vapor.

produced by low temperature carbonisation of coal.

Coke oven gas is a better fuel than blast furnace gas, because of its higher

calorific value, cleanliness and relatively low distribution cost (due to its low specific gravity).

heat release rate (thus requiring smaller combustion chamber).

Grindability index of a coal is 100. It implies that the

power consumption in grinding the coal will be very high.

coal can be pulverised with great difficulty.

power consumption in grinding the coal will be very high.

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

presence of large quantity of hydrogen in the fuel.

low calorific value of the fuel.

high sulphur content in the fuel.

lack of thorough mixing of fuel with air.

Theoretical flame temperature of a fuel is that temperature which is attained, when the fuel is completely burnt 'using theoretical amount of air in

either (a) or (b) without gain or loss of heat

During combustion of coal on grate, clinker formation is increased by the

low fusion point of ash (< 1100¬∞ C).

High rate of heating of coke ovens

may damage its walls due to abrupt excessive swelling of coal.

increases the time of carbonisation.

Low temperature carbonisation of coal produces

very low calorific value coke oven gas

Coalification means the

underground gasification of coal.

process of conversion of lignite into anthracite.

underground gasification of coal.

Anthracite can be used for

blending with highly coking coal to check its swelling which helps in saving coke even walls from damage and to produce high strength coke.

In low temperature carbonisation of coal as compared to high temperature carbonisation __________ produced is less.

difference in gross & net calorific value of the coke oven gas

yield of ammonia present in coke oven gas

1154 + Mcqs in Fuels And Combustion in Chemical Engineering Page 18 McqOptions

851.	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.
Answer» C. is not subjected to washing.

Discussion

852.	During its calorific value determination by bomb calorimeter, coal is combusted by
A.	air
B.	oxygen
C.	oxygen enriched air
D.	none of these
Answer» C. oxygen enriched air

Discussion

853.	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).
Answer» B. increases

Discussion

854.	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.
Answer» B. long flame.

Discussion

855.	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 (a), (b) and (a).
Answer» E.

Discussion

856.	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).
Answer» D. neither (a) nor (b).

Discussion

857.	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)
Answer» D. neither (a) nor (b)

Discussion

858.	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.
Answer» D. a black banded coal which burns with a non-smoky yellowish flame.

Discussion

859.	__________ is used as jet engine fuel.
A.	Petrol
B.	Diesel
C.	Kerosene
D.	LPG
Answer» D. LPG

Discussion

860.	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 (a), (b) & (c).
Answer» E.

Discussion

861.	Yield of pitch from distillation of high temperature tar is around __________ percent.
A.	10
B.	25
C.	65
D.	90
Answer» D. 90

Discussion

862.	Blast furnace gas constitutes mainly of
A.	N2 & CH4
B.	N2 & H2
C.	N2 & CO
D.	CH4 & CO2
Answer» D. CH4 & CO2

Discussion

863.	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 (a), (b) & (c).
Answer» E.

Discussion

864.	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.
Answer» B. has poor strength and abrasion resistance.

Discussion

865.	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
Answer» B. low ash

Discussion

866.	'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.
Answer» B. coke oven gas and converter gas.

Discussion

867.	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.
Answer» B. light oil and pitch.

Discussion

868.	Washing of coal does not reduce its
A.	S & P content.
B.	heating value.
C.	fusion point of ash.
D.	none of these.
Answer» E.

Discussion

869.	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.
Answer» D. none of these.

Discussion

870.	About __________ Nm3 of air will be required for the complete combustion of 2Nm3 of CO.
A.	2
B.	3
C.	5
D.	1
Answer» D. 1

Discussion

871.	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
Answer» B. CO, O2, CO2

Discussion

872.	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 (a), (b) and (c).
Answer» E.

Discussion

873.	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.
Answer» B. potassium hydroxide

Discussion

874.	Which of the following has the highest flame speed ?
A.	CO
B.	H2
C.	CH4
D.	C2H6
Answer» C. CH4

Discussion

875.	Percentage of carbon monoxide in blast furnace gas may be around
A.	8
B.	14
C.	22
D.	52
Answer» D. 52

Discussion

876.	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.
Answer» D. power consumption in grinding the coal will be very high.

Discussion

877.	Fuel combustion is never cent per cent efficient due to
A.	incomplete combustion
B.	dry gas/stack gas loss
C.	moisture loss
D.	all (a), (b) and (c)
Answer» E.

Discussion

878.	Which of the following is a poisonous fuel gas?
A.	Coke oven gas
B.	Blast furnace gas
C.	Natural gas
D.	None of these
Answer» C. Natural gas

Discussion

879.	The combustion reaction, C + O2 = CO2, is
A.	exothermic
B.	endothermic
C.	autocatalytic
D.	none of these
Answer» B. endothermic

Discussion

880.	The cuprous chloride used in orsat apparatus can absorb
A.	only CO
B.	both CO and CO2
C.	both CO and O2
D.	all CO, CO2, and O2.
Answer» E.

Discussion

881.	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
Answer» B. Coke oven gas

Discussion

882.	Mott and Wheeler test is conducted on coke to find its
A.	reactivity with O2.
B.	abradability.
C.	phosphorus content.
D.	volatile matter content.
Answer» B. abradability.

Discussion

883.	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.
Answer» E.

Discussion

884.	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 (b) without gain or loss of heat
Answer» E.

Discussion

885.	Abrasion index of blast furnace coke should be around __________ percent.
A.	20
B.	35
C.	55
D.	80
Answer» E.

Discussion

886.	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 (a), (b) & (c).
Answer» E.

Discussion

887.	Largest constituent of blast furnace gas is
A.	N2
B.	CO
C.	CO2
D.	H2
Answer» B. CO

Discussion

888.	Stoichiometric combustion of 12 kg of carbon requires __________ of oxygen.
A.	1kg mole
B.	22.4 Nm3
C.	32 kg
D.	all (a), (b) and (c)
Answer» E.

Discussion

889.	When the coal is heated in absence of air, it is called its
A.	deoxidation
B.	gasification
C.	coalification
D.	carbonisation
Answer» E.

Discussion

890.	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
Answer» D. 40

Discussion

891.	Which of the following is a lean fuel gas ?
A.	Coke oven gas
B.	LPG
C.	Blast furnace gas
D.	Natural gas
Answer» D. Natural gas

Discussion

892.	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.
Answer» B. produces larger size coke.

Discussion

893.	Low temperature carbonisation of coal produces
A.	metallurgical coke
B.	soft coke
C.	very low calorific value coke oven gas
D.	no by-products
Answer» C. very low calorific value coke oven gas

Discussion

894.	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.
Answer» B. underground gasification of coal.

Discussion

895.	Washing of coal is done to reduce the
A.	inherent impurities
B.	adhering impurities
C.	mineral matter
D.	both (b) and (c)
Answer» E.

Discussion

896.	'Fat' coal means a coal having
A.	low calorific value.
B.	high volatile matter,
C.	low ash content.
D.	non smoking tendency.
Answer» C. low ash content.

Discussion

897.	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 (a), (b) and (c).
Answer» E.

Discussion

898.	Blast furnace gas burns with a bluish flame, because of the presence of
A.	CO
B.	CH4
C.	CO2
D.	S
Answer» B. CH4

Discussion

899.	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
Answer» B. free carbon content in tar

Discussion

900.	Incomplete combustion of a fuel is characterised by the high __________ in the flue gas.
A.	smoke
B.	temperature
C.	oxygen
D.	carbon monoxide
Answer» E.

Discussion

Explore topic-wise MCQs in Chemical Engineering.

A coal with high ash content

During its calorific value determination by bomb calorimeter, coal is combusted by

As time passes, the calorific value of stored coal

Use of excess of combustion air in the combustion of fuels results in

Low temperature oxidation of stored coal results in the

The fuel ratio of a coal is

With increase in the oxygen content of the coal, its __________ decreases.

Lignite is

__________ is used as jet engine fuel.

Advantages of fluidised bed combustion are

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

Blast furnace gas constitutes mainly of

The main advantage of forced draft over natural draft is that

High ash containing coke

For long flame and easy ignition, the coal used should have

'Mixed gas' used in steel plants is a mixture of

Coal tar fuel - 200 (CTF 200) is a mixture of

Washing of coal does not reduce its

Soft coke is not

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

The sequence of absorption in flue gas analysis by Orsat's apparatus is respectively

Coke oven gas is a better fuel than blast furnace gas, because of its higher

In flue gas analysis by Orsat's apparatus, carbon monoxide is absorbed by

Which of the following has the highest flame speed ?

Percentage of carbon monoxide in blast furnace gas may be around

Grindability index of a coal is 100. It implies that the

Fuel combustion is never cent per cent efficient due to

Which of the following is a poisonous fuel gas?

The combustion reaction, C + O2 = CO2, is

The cuprous chloride used in orsat apparatus can absorb

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

Mott and Wheeler test is conducted on coke to find its

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

Theoretical flame temperature of a fuel is that temperature which is attained, when the fuel is completely burnt 'using theoretical amount of air in

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

During combustion of coal on grate, clinker formation is increased by the

Largest constituent of blast furnace gas is

Stoichiometric combustion of 12 kg of carbon requires __________ of oxygen.

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

Oxygen content in a flue gas was found to be 4%. It implies that excess air used for combustion was around __________ percent.

Which of the following is a lean fuel gas ?

High rate of heating of coke ovens

Low temperature carbonisation of coal produces

Coalification means the

Washing of coal is done to reduce the

'Fat' coal means a coal having

Anthracite can be used for

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

In low temperature carbonisation of coal as compared to high temperature carbonisation __________ produced is less.

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