A. Excessive power requirement of air blower
B. Enhanced sensible heat loss in the flue gas
C. Intermittent and uncontrolled combustion of the fuel
D. High exit flue gas temperature from the furnace
Related Mcqs:
- For the case of a fuel gas undergoing combustion with air, if the air/fuel ratio is increased, the adiabatic flame temperature will_____________________?
A. Increase
B. Decrease
C. Increase or decrease depending on the fuel type
D. Not change - Use of excess of combustion air in the combustion of fuels results in__________________?
A. Heat losses
B. Long flame
C. Condensation of water vapour from the fuel gas
D. None of these - Supply of excess air for complete combustion of fuel is necessitated to facilitate___________________?
A. Its thorough mixing with air
B. Attainment of chemical equilibrium
C. Attainment of high temperature
D. None of these - The optimum percentage of excess air for combustion depends upon the _______________ of the fuel?
A. Type (solid, liquid or gaseous)
B. Calorific value
C. Sulphur content
D. Ignition temperature - As the C/H ratio of the fuel increases, the amount of CO2 formed on combustion _______________ for the same percentage of excess air?
A. Decreases
B. Increases
C. Remain same
D. May increase or decrease depending on the type of fuel - 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 - High excess air in combustion of fuels results in____________________?
A. Increased fuel consumption
B. Incomplete combustion
C. Smoky flame
D. None of these - Oxygen content in a flue gas was found to be 4%. It implies that excess air used for combustion was around ______________ percent?
A. 4
B. 96
C. 20
D. 40 - Too much of excess air in combustion results in high___________________?
A. Fuel consumption for the same heat load
B. Stack gas temperature
C. Percentage of oxygen in flue gases
D. All A., B. and C. - Which of the following would require maximum amount of % excess air for complete combustion ?
A. Coke oven gas
B. Furnace oil
C. Pulverised coal
D. Lump coal (fixed on chain grate)
