Advantages of use of preheated combustion air are

Which of the following advantages is not associated with the use of preheated air for combustion of a fuel in the furnace?

A

Increase in calorific value of the fuel

B

Increase in flame temperature

C

Reduction in scale losses

D

Saving in fuel consumption

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

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

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

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

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

In a furnace operation, which is not preheated?

A

Solid fuels

B

Hydrocarbon containing fuel gases (e.g. coke oven gas, refinery gas etc.)

C

Both A and B

D

Neither A nor B

Advantages of fluidised bed combustion are

A

Reduced NO_x formation in flue gas

B

Lower furnace operating temperature

C

High heat transfer rate

D

All of the above

The most commonly used combustion system manufactured in India for the thermal power plant boilers is the __________ combustion system.

A

Pulverised fuel

B

Travelling grate stoker firing

C

Circulating fluidised bed

D

Fluidised bed

The combustion efficiency of a gas turbine using perfect combustion chamber is of the order of

A

75%

B

85%

C

90%

D

99%

Advantages of use of preheated combustion air are

Related Questions