Spontaneous combustion of coal on storage results due to

Improper storage condition results in the weathering of coal and spontaneous combustion, which increases its

A

friability & oxygen content

B

caking index

C

yield of carbonized products

D

calorific value

To avoid fire by spontaneous combustion of coal due to its low temperature oxidation, it should be stored in

A

Shallow and small piles

B

Fine sizes without the presence of any lump

C

Closed space without any ventilation facility

D

Large heaps with small surface to volume ratio

Low temperature oxidation and spontaneous combustion of freshly mined coal is accentuated, if

A

It contains large amount of volatile matter

B

It is stored in tall heaps

C

Smaller fines are stored in large quantity

D

All of the above

Pre-ignition is caused by the spontaneous combustion of the mixture before the end of the compression stroke, and is due to

A

Cylinder walls being too hot

B

Overheated spark plug points

C

Red hot carbon deposits on cylinder walls

D

Any one 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

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

Spontaneous combustion is a phenomenon in which

A

All the fuel burns instantaneously producing high energy release

B

Fuel burns with less air

C

Coal bursts into flame without any external ignition source but by itself due to gradual increase in temperature as a result of heat released by combination of oxygen with coal

D

Explosion in furnace

Calorific value of coal middling generated in coal washeries during washing of coal may be around __________ Kcal/kg.

A

1000

B

4000

C

6000

D

8000

Coal mines drainage waste water (acidic in nature) results from the earth's water percolating through the voids created in coal bed during mining. This polluted water which either drains out naturally to water courses or are removed before starting the mining is

A

Neutralised by alkali treatment

B

Left as such without any treatment

C

Diluted with fresh water to reduce its acidity

D

None of these

Spontaneous combustion of coal on storage results due to

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