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Home Chemical Engineering Fuels and Combustion Comments

  • Question
  • Explosion limit of blast furnace gas is 37 to 71% gas in gas-air mixture. It means that the blast furnace gas will explode when burnt in a confined space, if its concentration in the gas-air mixture is __________ percent.


  • Options
  • A. < 37%
  • B. >71%
  • C. in between 37 & 71%
  • D. none of these

  • Correct Answer
  • in between 37 & 71% 


  • Fuels and Combustion problems


    Search Results


    • 1. Which of the following accentuates clinker-ing trouble on furnace grate burning coal?

    • Options
    • A. Low reactivity of carbonised residue containing high proportions of iron & sulphur.
    • B. Low forced draught and fuel bed temperature.
    • C. Thick fire bed and preheated primary air.
    • D. All (a), (b) and (c).
    • Discuss
    • 2. Junker's calorimeter is used to determine the calorific value of

    • Options
    • A. pulverised coal
    • B. gaseous fuels
    • C. fuel oil
    • D. none of these
    • Discuss
    • 3. Gray King Assay and Swelling Index of a coal is a measure of its

    • Options
    • A. swelling characteristics.
    • B. abradability.
    • C. agglutinating properties.
    • D. resistance to impact breakage.
    • Discuss
    • 4. Which of the following is used for making the explosive 'TNT'?

    • Options
    • A. Benzol
    • B. Toluene
    • C. Pyridine
    • D. Cerosote
    • Discuss
    • 5. High temperature in gasification of coal favours

    • Options
    • A. high production of CO2.
    • B. low production of CO2.
    • C. high production of CO.
    • D. both (b) and (c).
    • Discuss
    • 6. Actual flame temperature is always lower than the adiabatic flame temperature, because there is

    • Options
    • A. no possibility of obtaining complete combustion at high temperature.
    • B. always loss of heat from the flame.
    • C. both (a) and (b).
    • D. neither (a) nor (b).
    • Discuss
    • 7. 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
    • 8. 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
    • 9. 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
    • 10. 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


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