The maximum percentage of CO2 in a flue gas (from a carbonaceous fuel) can be_________________?

Related Mcqs:

1. A carbonaceous fuel (containing no H2 or hydrocarbons) is burnt and the resulting flue gas contains 21% CO2. It means that___________________?

   A. 21% excess air has been used for combustion
   B. 21% excess oxygen has been used for combustion
   C. Complete combustion of fuel has taken place
   D. No excess air has been used for combustion

2. The calorific value of a gas of composition CO2 = 20%, H2 = 50%, CH4 = 30%, is y. If the composition of gas is changed to H2 = 50%, CH4 = 30%, CO2 = 10%, N2 = 10%, then the calorific value will be___________________?

   A. y
   B. 0.95 y
   C. 1.05 y
   D. 1.8 y

3. The average molecular weight of a flue gas having the composition by volume as CO2 = 25%, O2 = 25%, N2 = 50% will be___________________?

   A. 27.6
   B. 23
   C. 47.3
   D. 42.9

4. Pure carbon is completely burnt in oxygen. The flue gas analysis is 70%CO2, 20%CO and 10%O2. The percent excess oxygen used is __________________?

   A. 20
   B. 12.5
   C. 0
   D. 10

5. 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?

   A. 71%
   C. In between 37 & 71%
   D. None of these

6. Incomplete combustion of a fuel is characterised by the high _______________ in the flue gas?

   A. Smoke
   B. Temperature
   C. Oxygen
   D. Carbon monoxide

7. A liquid/gaseous fuel containing hydrocarbons and high amount of sulphur is burnt with 40% excess air. The flue gas still contains large amount of carbon monoxide. This may be due to the_________________?

   A. Presence of large quantity of hydrogen in the fuel
   B. Low calorific value of the fuel
   C. High sulphur content in the fuel
   D. Lack of thorough mixing of fuel with air

8. Efficiency of the combustion of a fuel is judged by the ______________ the flue gas?

   A. % of CO2 in
   B. % of O2in
   C. Temperature of
   D. Colour of

9. If oxygen content in the flue gas rises too high, fuel is being wasted by _______________?

   A. Incomplete combustion
   B. Dry gas/stack gas loss
   C. Moisture loss
   D. None of these

10. White flue gas (resembling steam) coming out of the chimney of a thermal power plant indicates that the fuel used in the boiler furnace is_______?

    A. Tar
    B. Sulphide Coke
    C. Coke Oven Gas
    D. Pulverised coke

    Submitted by: Muhammad Mutsadiq Umer