A. Calorific value of the fuel
B. Flame temperature achieved
C. Speed of combustion of fuel
D. Heat transfer rate to the stock in the furnace
Related Mcqs:
- Furnace oil consumption in a furnace for a given duty employing preheated combination air (at 300°) may be reduced by about ______________ percent as compared to the use of atmospheric combustion air?
A. 5
B. 10
C. 20
D. 35 - Use of preheated air for combustion of fuel in the furnace, increases the___________________?
A. Scale losses of the furnace stock
B. Calorific value of the fuel
C. Flame temperature
D. None of these - 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 - Temperature of preheated air used for the transportation of pulverised coal through pipes to the burner of a boiler furnace is restricted to a maximum limit of about 300° C to avoid the___________________?
A. Requirement of large volume combustion chamber
B. Risk of explosion
C. Chances of clinker formation
D. Incomplete combustion of coal - 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 - Deficiency of combustion air during combustion of a gaseous fuel_____________________?
A. Lengthens the flame
B. Causes heat loss of fuel by its partial combustion
C. Both A. & B.
D. Shortens the flame - Correct viscosity of furnace oil at the burner tip for proper atomisation is about 25 centistokes. To reduce the viscosity of high viscosity furnace oil (250 centistokes) to the correct atomisation viscosity (i.e. 25 cst), it should be preheated to about ______________°C?
A. 70
B. 85
C. 105
D. 145 - 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 - During combustion of coal on grate, clinker formation is increased by the___________________?
A. Use of thick fire bed
B. Low fusion point of ash (< 1100° C)
C. Use of preheated primary air
D. All A., B. & 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)
