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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