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
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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
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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
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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
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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
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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
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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
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If CO2 is not fully absorbed by the KOH solution meant for its absorption in the orsat apparatus, it will appear as
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Which of the following has the highest calorific value (kcal/Nm3 )?
A. Carburetted water gas
B. Gobar gas
C. Natural gas
D. LPG
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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
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Caking index of coal blend used for blast furnace coke making is about
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Purity of coke means that, it is high in carbon and low in
A. Volatiles
B. Ash
C. Iron
D. Moisture
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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
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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
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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
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Junker's calorimeter is used to determine the calorific value of
A. Pulverised coal
B. Gaseous fuels
C. Fuel oil
D. None of these
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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
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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
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The hottest part of the flame lies in its____zone.
A. Non-luminous
B. Luminous
C. Yellow
D. Unburnt gases
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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
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