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_________________?

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. A fuel containing carbon and carbon monoxide (but containing no hydrogen or its compounds) is burnt in pure oxygen at constant pressure. Its gross calorific value as compared to net calorific value will be_________________?

   A. More
   B. Less
   C. Same
   D. Data insufficient; can’t be predicted

3. 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

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. A sample of natural gas containing 80% methane (CH4) and rest nitrogen (N2) is burnt with 20% excess air. With 80% of the combustibles producing CO2 and the remainder going to CO, the Orsat analysis in volume percent is_________________?

   A. CO2 : 6.26, CO : 1.56, O2 : 3.91, H2O :15.66, N2 : 72.60
   B. CO2 : 7.42, CO : 1.86, O2 : 4.64, N2:86.02
   C. CO2 : 6.39, CO : 1.60, O2 : 3.99, H2O:25.96, N2:72.06
   D. CO2 : 7.60, CO : 1.90, O2 : 4.75, N2 : 85.74

6. Theoretical flame temperature of a fuel is that temperature which is attained, when the fuel is completely burnt ‘using theoretical amount of air in___________________?

   A. Air
   B. Oxygen
   C. Either A. or B.
   D. Either A. or B. without gain or loss of heat

7. In flue gas analysis by Orsat’s apparatus, carbon monoxide is absorbed by__________________?

   A. Cuprous chloride
   B. Potassium hydroxide
   C. Alkaline pyrogallol solution
   D. None of these

8. Fuel gases containing hydrocarbons (e.g. coke oven gas) are not preheated before burning, mainly because __________________?

   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

9. Gasification of the solid fuel converts its organic part into combustible by interaction with air/oxygen and steam so as to obtain a secondary gaseous fuel of high calorific value having no ash. Gasification reactions are normally carried out at about _____________ °C?

   A. 400-500
   B. 900-1000
   C. 1400-1500
   D. 1700-1800

10. High sulphur content in a fuel ______________ of the flue gases?

    A. Decreases the dew point
    B. Increases the dew point
    C. Reduces the combustion efficiency by limiting the permissible temperature reduction
    D. Both B. and C.