Fuel Utilization In analyzing utilization of heat from fuel combustion, both amount of heat and the temperature are important since furnace is heated by the heat transfer from POC. Heat transfer rate is proportional to the temperature difference between temperature of POC and the furnace. In this connection adiabatic flame temperature is a very important parameter for fuel utilization (Fuel utilization and heat utilization are essentially similar since heat is derived from combustion of fuel.

An obvious requirement is that the flame temperature must be greater than furnace temperature so that POC is able to transfer heat for heating. Rapid heating of the furnace is achieved by greater temperature difference, which means higher flame temperature. Higher flame temperature, though increases the heat transfer rate but at the same time it may cause overheating and destroy the lining. We have seen in lecture 13 that adiabatic flame temperature (AFT) decreases with increase in excess air. Control of excess air is important to utilize fuel effectively.