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Chemical Engineering :: Fuels and Combustion

  1. Presence of force moisture in coal is most disadvantageous during its

  2. A.
    transportation and handling
    B.
    washing
    C.
    pulverisation
    D.
    storage

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  3. Tar is a better fuel than furnace oil, because of its

  4. A.
    higher calorific value.
    B.
    lower sulphur content.
    C.
    higher emissivity (0.8 - 0.9) resulting in higher radiation heat transfer rate.
    D.
    both (a) and (b).

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  5. With increase in moisture content of coal, its

  6. A.
    calorific value increases.
    B.
    caking properties diminish.
    C.
    swelling during carbonisation becomes excessive.
    D.
    none of these.

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  7. Main constituent of natural gas is

  8. A.
    CH4 (upto 90%)
    B.
    C2H6
    C.
    C3H8
    D.
    H2

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  9. For the case of a fuel gas undergoing combustion with air, if the air/fuel ratio is increased, the adiabatic flame temperature will

  10. A.
    increase
    B.
    decrease
    C.
    increase or decrease depending on the fuel type
    D.
    not change

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  11. Ignition temperature decreases progressively from anthracite to lignite, because

  12. A.
    volatile matter content increases.
    B.
    carbon content decreases.
    C.
    moisture content increases.
    D.
    ash content increases.

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  13. Which of the following fuel gases is heavier than air ?

  14. A.
    Blast furnace gas
    B.
    Coke oven gas
    C.
    Natural gas
    D.
    Water gas

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  15. Correct viscosity of furnace oil at the burner tip for proper atomisation is about 25 centistokes. To reduce the viscosity of high viscosity furnace oil (250 centistokes) to the correct atomisation viscosity (i.e. 25 cst), it should be preheated to about____°C.

  16. A.
    70
    B.
    85
    C.
    105
    D.
    145

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  17. Theoretical flame temperature of a fuel is that temperature which is attained, when the fuel is completely burnt 'using theoretical amount of air in

  18. A.
    air
    B.
    oxygen
    C.
    either (a) or (b)
    D.
    either (a) or (b) without gain or loss of heat

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  19. Use of preheated air for combustion of fuel in the furnace, increases the

  20. A.
    scale losses of the furnace stock.
    B.
    calorific value of the fuel.
    C.
    flame temperature.
    D.
    none of these.

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