Underfeed stokers work best for __________ coals high in volatile matter and with caking tendency

A coal having high ratio of volatile matter to fixed carbon as compared to a coal having low ratio of volatile matter to fixed carbon

A

Is less liable to spontaneous combustion on storage

B

Is more difficult to ignite and produces a shorter flame

C

Requires smaller combustion space and less secondary air

D

None of these

'Fat coals' are those coals which have very high

A

Caking capacity

B

Volatile matter content

C

Fusion point of its ash

D

Inherent moisture content

Caking coals are those which

A

Form lumps or masses of coke

B

Burn freely

C

Show little or no fusing action

D

Burn completely

Highly caking coals

A

Produce weak coke

B

Produce strong coke

C

May damage the coke oven walls during carbonisation

D

Both B and C

Powdery materials can be guarded against caking tendency on storage by

A

Providing irregular grain size

B

Providing minimum percentage of voids

C

Having maximum possible points of contact

D

None of these

Assam coals suffers mainly from the disadvantage of high __________ content.

A

Ash

B

Volatile matter

C

Sulphur (4-6%)

D

Moisture

A coal having high volatile matter content will

A

Give less yield of tar and gas on carbonisation

B

Burn with a small non-smoky flame

C

Have a very high calorific value

D

None of these

A coal having high amount of volatile matter

A

Would require smaller combustion chamber

B

Produces very little of tar and gas on carbonisation

C

Ignites easily and burns with long smoky flame

D

All of the above

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

High ash coals

A

Are soft & friable (poor strength and size stability)

B

Require longer time of carbonisation as ash offers resistance to heat transfer

C

Produce larger quantity of coke oven gas

D

None of these

Underfeed stokers work best for __________ coals high in volatile matter and with caking tendency

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