Question: As the equilibrium moisture content of the coal increases, its
[A].

calorific value increases.

[B].

swelling number decreases.

[C].

swelling number increases.

[D].

bulk density decreases.

Answer: Option B

Explanation:

No answer description available for this question.

Question: Caking coal is desirable for
[A].

burning on travelling grate.

[B].

coke making.

[C].

burning on firebars.

[D].

all (a), (b) and (c).

Answer: Option B

Explanation:

No answer description available for this question.

Question: 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.

Answer: Option A

Explanation:

No answer description available for this question.

Question: Gross calorific value will be equal to the net calorific value for
[A].

H2

[B].

C2H2

[C].

CO

[D].

C2H6

Answer: Option C

Explanation:

No answer description available for this question.

Question: A coal with high ash content is undesirable, as
[A].

it is abrasive to the coal pulveriser (ie.g. ball mill) and the combustion chamber.

[B].

the ash in molten condition gets absorbed in the pores of the refractory lining of the furnace and causes its spalling due to different co-efficient of expansion/contraction of the refractory and the ash.

[C].

the ash retains the sulphur & phosphorus and thus affects the quality of products in metallurgical furnace apart from increasing the slag volume. Besides, it may fuse and stick to the boiler tubes thereby reducing the heat transfer.

[D].

all (a), (b) and (c).

Answer: Option D

Explanation:

No answer description available for this question.

Question: A coal with high __________ content, would ignite most easily.
[A].

fixed carbon

[B].

volatile matter

[C].

ash

[D].

oxygen

Answer: Option B

Explanation:

No answer description available for this question.

Question: 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 (a), (b) and (c).

Answer: Option D

Explanation:

No answer description available for this question.

Question: Low temperature oxidation of stored coal results in the
[A].

decrease in its caking power & calorific value.

[B].

decrease in its carbon & hydrogen content.

[C].

increase in its oxygen content.

[D].

all (a), (b) and (a).

Answer: Option D

Explanation:

No answer description available for this question.