Efficient burning of anthracite coal requires

Calorific value of a typical dry anthracite coal may be around __________ Kcal/kg.

A

1000

B

4000

C

8000

D

15000

Anthracite coal

A

Contains more volatile matter than bituminous coal

B

Ignites more easily than bituminous coal

C

Is essentially a coking coal

D

Burns with short, bluish, yellow-tipped flame producing very little smoke

A travelling grate stoker is meant for the efficient burning of __________ coal.

A

Caking

B

Pulverised

C

Non-caking

D

High ash

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

If h₁ = inner film co-efficient and /h₂ = outer film co-efficient, then the overall heat transfer co-efficient is

A

Always less than h₁

B

Always between h₁ and h₂

C

Always higher than h₂

D

Dependent on metal resistance

Anthracite can be used for

A

Recarbonising steel

B

Making carbon electrodes

C

Blending with highly coking coal to check its swelling which helps in saving coke even walls from damage and to produce high strength coke

D

All of the above

Ignition temperature decreases progressively from anthracite to lignite, because

A

Volatile matter content increases

B

Carbon content decreases

C

Moisture content increases

D

Ash content increases

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 accentuates clinker-ing troubles on furnace grate burning coal?

A

Low reactivity of carbonised residue containing high proportion of iron & sulphur

B

Low forced draft & fuel bed temperature

C

Thick firebed and preheated primary air

D

All of the above

The open "Sigrees" or coal stoves often require fanning to sustain burning because of

A

Tendency of carbon dioxide to form a layer along with dust smoke

B

Lack of oxygen in the surroundings of sigrees

C

Accumulation of smoke and dust over the sigrees

D

Interrupted release of moisture from the material

Efficient burning of anthracite coal requires

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