Oxygen content in a flue gas was found to be 4%. It implies that excess air used for combustion was around ______________ percent?

A. Emissivity factor is higher
B. Sulphur content is lower
C. Flue gas has lower dew point thereby facilitating more waste heat recovery
D. All A., B. and C.

A. Proper fuel preparation
B. Keeg the flue gas exhaust temperature very high
C. Adopting efficient-fuel firing technique & equipment
D. Supplying correct quantity of combustion air

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

A. 200 meters
B. Infinitely long
C. More than 105.7 metres
D. Equal to the height of the hot gas column producing draught

A. Calorific value
B. Higher C/H ratio
C. Sulphur content
D. Difference in gross & net calorific value