The main function of primary air in pulverised coal fired burner is to

In case of pulverised coal fired steam boiler, the secondary air serves the main purpose of

A

Transportation of coal

B

Drying of coal

C

Combustion of coal by supplying it around the burner

D

Preheating the primary air

If fuel and air are mixed ahead of the burner, it is called a/an __________ burner.

A

Premix

B

Outside mixing type

C

Rotary

D

Diffusion

Bunsen burner is an example of a/an __________ burner.

A

inside mixing/premix type

B

submerged combustion

C

rotary cup

D

outside mixing/diffusion flame/nozzle mix type

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

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

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

Pulverised fuel fired furnaces employ __________ fuel firing.

A

Horizontal

B

Vertical

C

Tangential

D

All of the above

The excess air required for the combustion of pulverised coal is of the order of about __________ percent.

A

5

B

15

C

30

D

45

Limestone powder is injected during pulverised coal burning in boilers to __________ the flue gases.

A

Reduce SO₂ content in

B

Catalytically convert SO₂ to SO₃ in

C

Increase the dew point of

D

None of these

Which of the following is the most important deterrants to an extended use of pulverised coal in boiler firing?

A

Ash disposal problem

B

Excessive fly ash discharge from the stack

C

Higher power consumption in its transportation

D

Erosion of induced draft fan blades

The main function of primary air in pulverised coal fired burner is to

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