The efficiency of chimney is approximately

Draught produced by a tall chimney due to density difference between hot flue gas inside the Chimney and atmospheric air outside the chimney is more appropriately known as the __________ draught.

A

Natural

B

Induced

C

Forced

D

Chimney

The draught produced by steel chimney as compared to that produced by brick chimney for the same height is

A

Less

B

More

C

Same

D

May be more or less

The draught produced, for a given height of the chimney and given mean temperature of chimney gases

A

decreases with increase in outside air temperature

B

increases with increase in outside air temperature

C

remains the same irrespective of outside air temperature

D

may increase or decrease with increase in outside air temperature

The maximum discharge through a chimney occurs when the height of chimney is

A

Infinitely long

B

Around 200 meters

C

Equal to the height of the hot gas column producing draught

D

Outside temperature is very low

TREE is to GROUND as CHIMNEY is to

A

SMOKE

B

BRICK

C

SKY

D

GARAGE

Flue gas discharge velocity through chimney of a big thermal power plant may be around __________ m/sec.

A

0.5

B

500

C

10

D

50

Gradually increasing temperature of flue gases at inlet to chimney for given steam outputs is an indication of

A

Higher effectiveness of boiler

B

High calorific value coal being burnt

C

Fouling of heat transfer surfaces

D

Raising of steam temperature

The draught produced by chimney of given height at given outside temperature

A

decreases if the chimney gas temperature increases

B

increases if the chimney gas temperature increases

C

remains same irrespective of chimney gas temperature

D

may increase or decrease

For forced draught system, the function of chimney is mainly

A

to produce draught to accelerate the combustion of fuel

B

to discharge gases high up in the atmosphere to avoid hazard

C

to reduce the temperature of the hot gases discharged

D

none of the above

Black smoke coming out of the chimney of a furnace is an indication of the use of __________ in the furnace.

A

Low amount of excess combustion air

B

Large quantity of excess combustion air

C

Hydrocarbon fuel

D

Pulverised coal as fuel

The efficiency of chimney is approximately

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