Furnace Technology
Overfire burning in a furnace is a phenomenon characterised by

Supply of excess air
Burning carbon monoxide and other incombustible in upper zone of furnace by supplying more air
Supply of excess fuel
None of these

ANSWER DOWNLOAD EXAMIANS APP

Furnace Technology
In practical operation of any furnace, zero oxygen percentage or theoretical CO₂ percentage in flue gas is rarely achieved, because of

Use of non-preheated combustion air
Use of excessive positive draft in the furnace
Use of pulverised solid fuels
Imperfect mixing of fuel & air and infiltration of air

ANSWER DOWNLOAD EXAMIANS APP