Fuels and Combustion problems
- 1. A coal having high amount of volatile matter
Options- 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). Discuss
Correct Answer: all (a), (b) and (c).
- 2. Higher percentage of ash in coal meant for the production of metallurgical grade coke
Options- A. decreases the hardness of coke.
- B. decreases the abrasion resistance of coke.
- C. causes brittleness in steel.
- D. none of these. Discuss
Correct Answer: none of these.
- 3. Improper storage condition results in the weathering of coal and spontaneous combustion, which increases its
Options- A. caking index.
- B. yield of carbonised products.
- C. friability & oxygen content.
- D. calorific value. Discuss
Correct Answer: friability & oxygen content.
- 4. A coal with high ash content is undesirable, as
Options- 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). Discuss
Correct Answer: all (a), (b) and (c).
- 5. Laboratory gas is obtained by the cracking of
Options- A. gasoline
- B. diesel
- C. fuel oil
- D. kerosene Discuss
Correct Answer: kerosene
- 6. When incomplete combustion loss is high, the flue gas analysis shows large amount of
Options- A. CO2
- B. CO
- C. O2
- D. C Discuss
Correct Answer: CO
- 7. The internal energy of the combustion products is __________ compared to that of reactants.
Options- A. more
- B. less
- C. equal
- D. more or less ; (depends on the state of fuel.) Discuss
Correct Answer: less
- 8. Combustion of pulverised coal as compared to that of lump coal
Options- 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. Discuss
Correct Answer: can be done with less excess air.
- 9. Pick out the wrong statement.
Options- A. LPG is also used as fuel for automobiles & small furnaces and for cutting & welding of metals.
- B. The minimum temperature, at which a petroleum oil vapor catches fire and continues to burn, is called its flash point.
- C. Each ton of petroleum oil on distillation produces about 30-50 Nm3 of gas.
- D. Maximum yield of naphthalene is obtained on distillation of crude oil. Discuss
Correct Answer: The minimum temperature, at which a petroleum oil vapor catches fire and continues to burn, is called its flash point.
- 10. 'Wobbe index' is a characteristic of
Options- A. solid fuels
- B. gaseous fuels
- C. liquid fuels
- D. fat coals Discuss
Correct Answer: gaseous fuels
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