Fuel Combustion and Pollution Emissions MCQ Questions - Set 25 - ObjectiveBooks

Fuel Combustion and Pollution Emissions MCQ Questions - Set 25

Practice Test: Question Set - 25

1. Which of the following accentuates clinkering trouble on furnace grate burning coal?
    (A) Low reactivity of carbonized 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)

2. Efficiency of the combustion of a fuel is judged by the __________ the flue gas.
    (A) % of CO2 in
    (B) % of O2 in
    (C) Temperature of
    (D) Color of

3. Gross heating value of coal is __________ the net heating value.
    (A) Higher than
    (B) Lower than
    (C) Same as
    (D) Either (a) or (b); depends on the type of coal

4. Which of the following is not applicable to fluidized bed combustion of coal?
    (A) It cannot burn low grade coal
    (B) It achieves higher fuel combustion efficiency
    (C) Less heat transfer surface area is required in boilers
    (D) None of these

5. Which of the following is the most poisonous gas?
    (A) Coke oven gas
    (B) Producer gas
    (C) Blast furnace gas
    (D) L.D. converter gas

6. A coal with high ash content is undesirable, as
    (A) It is abrasive to the coal pulveriser (i.e. 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)

7. With increase in calorific value of fuels, their adiabatic flame temperatures
    (A) Increase
    (B) Decrease
    (C) Remain unchanged
    (D) May increase or decrease; depends on the quantity of products of combustion

8. Percentage of hydrogen in coke oven gas may be around
    (A) 10
    (B) 25
    (C) 45
    (D) 60

9. Low temperature carbonization of coal takes place at __________ °C.
    (A) 300
    (B) 1100
    (C) 700
    (D) 150

10. Soft coke is not
    (A) Produced by low temperature carbonization of coal
    (B) A domestic fuel
    (C) Used in blast furnaces
    (D) None of these

11. Prime coking coal is always blended with medium or non- coking coal before carbonization
    (A) To check against its excessive swelling during heating, which may exert high pressure and damage coke oven walls
    (B) Because, it alone produces unreactive coke
    (C) Both (a) and (b)
    (D) Neither (a) nor (b)

12. Coke ovens in steel plant are heated by
    (A) Electricity
    (B) Coke oven gas
    (C) Mixed gas
    (D) Both (b) & (c)

13. Which of the following is not a manufactured fuel?
    (A) Furnace oil
    (B) Bagasse
    (C) Semi-coke
    (D) Kerosene

14. Bomb calorimeter is used for the determination of calorific value of the __________ fuels.
    (A) Gaseous
    (B) Solid
    (C) Liquid
    (D) Both (b) and (c)

15. In high temperature carbonization (as compared to low temperature carbonization) of coal, the
    (A) Gas yield is less
    (B) Tar yield is more
    (C) Ignition temperature of coke produced is less
    (D) Aromatic content of tar produced is more

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