During combustion of coal on grate, clinker formation is increased by the

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 reason for excessive clinker formation in gas producers is the

A

Use of coal/coke containing a high % of fines and ash

B

Use of fuel having too low an ash fusion temperature

C

Development of hot spots in the fuel bed and an abnormally high rate of gasification

D

All of the above

The best suited coal for chain or traveling grate stoker boiler is

A

Coking coal

B

Non-coking or free burning coal

C

Pulverized coal

D

High sulphur coal

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

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

Cement clinker is reduced to fine size by a

A

Roll crusher

B

Ball mill

C

Tube mill

D

Hammer mill

Which of the following types of coal represents the first stage of formation of coal?

A

Anthracite

B

Lignite

C

Peat

D

Bituminous

Deficiency of combustion air during combustion of a gaseous fuel

A

Lengthens the flame

B

Causes heat loss of fuel by its partial combustion

C

Both A & B

D

Shortens the flame

During combustion of coal on grate, clinker formation is increased by the

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