High Space Heat Release and Low Excess Air Combustion of Heavy Fuel Oil Using Exhaust Gas Recirculation Method

It is known that in low excess air combustion of boilers for the reduction of corrosion of low temperature heating surfaces, soot formation increases and in application of high space heat release combustion for making a boiler smaller in size, overheating of combustion chamber wall occurs. Then in order to carry out high space heat release and low excess air combustion without above-mentioned difficulties authors applied exhaust gas recirculation method (mixing combustion air with exhaust gas) to heavy tuel oil firing equipment with pre-combustion chamber and studied on the merits of this method. The main results are as follows : (1) At heat release rate 107 kcal/m3hr and excess air factor 1.03, combustion was almost completed in pre-combustion chamber ; soot formation was very little (70 mg/Nm3) and more reduced by exhaust gas recirculation. (2) Acid dewpoint was slightly decreased by exhaust gas recirculation. (3) Gas temperature in pre-combustion chamber dropped and became uniform with increase of recirculated exhaust gas.