Chemical Engineering - Fuels and Combustion

16. 

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.

Answer: Option B

Explanation:

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17. 

Which of the following is not a by-product fuel ?

A. Pitch
B. Blast furnace gas
C. Petrol
D. Refinery gas

Answer: Option C

Explanation:

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18. 

Preheating of combustion air is done to

A. increase the adiabatic flame temperature.
B. increase the calorific value of the fuel.
C. complete the combustion of fuel.
D. reduce its requirement for effecting the complete combustion.

Answer: Option A

Explanation:

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19. 

Gross heating value of coal is __________ the net heating value.

A. higher than
B. lower than
C. same as
D. either (a) or (b); depends on the type of coal

Answer: Option A

Explanation:

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20. 

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

Answer: Option D

Explanation:

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