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  • Question
  • Presence of free moisture in coal during its high temperature carbonisation


  • Options
  • A. reduces the coking time.
  • B. protects the volatile products from pyrolysis (cracking) in the presence of hot coke and hot oven walls.
  • C. increases the loss of fine coal dust from the ovens when charging.
  • D. none of these.

  • Correct Answer
  • protects the volatile products from pyrolysis (cracking) in the presence of hot coke and hot oven walls. 


  • Fuels and Combustion problems


    Search Results


    • 1. Low temperature carbonisation

    • Options
    • A. is mainly for producing the smokeless domestic coke.
    • B. is meant for the production of 'metallurgical coke'.
    • C. produces higher quantity of gas than high temperature carbonisation.
    • D. produces less quantity of tar than high temperature carbonisation.
    • Discuss
    • 2. The gas which contributes maximum to the heating value of natural gas is

    • Options
    • A. CO
    • B. CO2
    • C. H2
    • D. CH4
    • Discuss
    • 3. Gross and net calorific value of a fuel will be the same

    • Options
    • A. if its ash content is zero.
    • B. ifits carbon content is very low.
    • C. if its hydrogen/hydrogen compound content is zero.
    • D. under no circumstances.
    • Discuss
    • 4. The temperature at which plastic layer formation takes place during carbonisation of coal varies from __________ °C.

    • Options
    • A. 100 to 150
    • B. 350 to 450
    • C. 550 to 650
    • D. 700 to 850
    • Discuss
    • 5. Which of the following gaseous fuels has the lowest calorific value?

    • Options
    • A. Gobar gas
    • B. Refinery gas
    • C. Converter gas
    • D. Blast furnace gas
    • Discuss
    • 6. Natural draught produced by a chimney depends upon the

    • Options
    • A. density of the chimney gases.
    • B. height of the chimney.
    • C. both (a) and (b).
    • D. neither (a) nor (b).
    • Discuss
    • 7. Calorific value of coal middling generated in coal washeries during washing of coal may be around __________ Kcal/kg.

    • Options
    • A. 1000
    • B. 4000
    • C. 6000
    • D. 8000
    • Discuss
    • 8. Fuel gases containing hydrocarbons (ie.g. coke oven gas) are not preheated before burning, mainly because

    • Options
    • A. the hydrocarbons crack thereby choking and fouling the heat transfer surface by carbon soot.
    • B. it reduces its calorific value tremendously.
    • C. it reduces its flame temperature tremendously.
    • D. there are chances of explosion during preheating.
    • Discuss
    • 9. Which of the following is the most reactive (as regards the formation of CO + H2 from C + H2O)?

    • Options
    • A. Blast furnace coke
    • B. Low temperature coke
    • C. Anthracite coal
    • D. Sub-bituminous coal
    • Discuss
    • 10. Which of the following is not a product of tar distillation?

    • Options
    • A. Phenol & naphthalene
    • B. Benzol & pitch
    • C. Anthracene & creosote
    • D. None of these
    • Discuss


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