Supply of excess air for complete combustion of fuel is necessitated to facilitate

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

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

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

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

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

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)

__________ fuels require the maximum percentage of 'excess air' for complete combustion.

A

Solid

B

Liquid

C

Gaseous

D

Nuclear

Air/fuel ratio by weight for combustion of methane with theoretical quantity of air will be about

A

9:1

B

17 : 1

C

23 : 1

D

29 : 1

Air/fuel ratio on molar (volume) basis for combustion of methane with theoretical quantity of air with be

A

9.5:1

B

12.5:1

C

15.5 :1

D

18.5 : 1

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

Supply of excess air for complete combustion of fuel is necessitated to facilitate

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