Fuel Combustion Quality Questions with Answers - Set 27 - ObjectiveBooks

Fuel Combustion Quality Questions with Answers - Set 27

Practice Test: Question Set - 27

1. Higher efficiency in the combustion of solid fuel cannot be achieved by
    (A) Proper fuel preparation
    (B) Keeping the flue gas exhaust temperature very high
    (C) Adopting efficient-fuel firing technique & equipment
    (D) Supplying correct quantity of combustion air

2. Which of the following has the highest flame speed?
    (A) CO
    (B) H2
    (C) CH4
    (D) C2H6

3. Ultimate analysis of coal determines its __________ content.
    (A) Carbon, hydrogen, nitrogen & sulphur
    (B) Carbon, ash, sulphur & nitrogen
    (C) Carbon, sulphur, volatile matter & ash
    (D) Carbon, volatile matter, ash & moisture

4. For maximum discharge through a chimney, its height should be
    (A) 200 meters
    (B) Infinitely long
    (C) More than 105.7 meters
    (D) Equal to the height of the hot gas column producing draught

5. Pick out the wrong statement.
    (A) High concentration of oxygen in flue gas means high stack loss
    (B) Gaseous fuels require the least % excess air for complete combustion
    (C) The ratio of fixed carbon to volatile matter percentage in coal is called its 'fuel ratio'
    (D) Calorific value of natural gas is more than that of LPG

6. Presence of __________ in a dry gaseous fuel does not contribute to its calorific value.
    (A) Sulphur
    (B) Oxygen
    (C) Hydrogen
    (D) Carbon

7. A particular coal is said to be free burning when it
    (A) Burns completely
    (B) Gives smokeless burning
    (C) Shows little or no fusing action
    (D) None of these

8. Ammonia content in raw coke oven gas is about __________ gm/Nm3.
    (A) 1
    (B) 5
    (C) 50
    (D) 100

9. Critical Air Blast (CAB) value of coke is a direct measure of its
    (A) Reactivity
    (B) Hardness
    (C) Strength
    (D) None of these

10. The maximum adiabatic flame temperature in air as compared to that in pure oxygen is
    (A) Much lower
    (B) Much higher
    (C) Same
    (D) Either lower or higher, depends on the type of fuel

11. Improper storage condition results in the weathering of coal and spontaneous combustion, which increases its
    (A) Caking index
    (B) Yield of carbonized products
    (C) Friability & oxygen content
    (D) Calorific value

12. Calorific value of wood gas is about __________ kcal/Nm3.
    (A) 1500
    (B) 3300
    (C) 5400
    (D) 8500

13. The sequence of absorption in flue gas analysis by Orsat's apparatus is respectively
    (A) CO2, O2, CO
    (B) CO, O2, CO2
    (C) CO2, CO, O2
    (D) O2, CO2, CO

14. Oxygen required for theoretically complete combustion of 1 Nm3 methane is __________ Nm3.
    (A) 2
    (B) 4
    (C) 6
    (D) 1

15. Sometimes water is sprayed during coal charging in the coke oven, which helps in
    (A) Prevention of clinker formation in the oven
    (B) Controlling the dust nuisance while charging the coal
    (C) Reducing the cracking of hydrocarbons in the gas and increasing the percentage of CO & H2 in the gas (due to the endothermic reaction represented by C + H2O = CO + H2)
    (D) All (a), (b) and (c)

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