Comparisons of combustion characteristics between bioliquid and heavy fuel oil combustion in a 0.7 MWth pilot furnace and a 75 MWe utility boiler

Abstract This study compared the combustion characteristics between bioliquid and heavy fuel oil using a 0.7 MWth pilot furnace and a 75 MWe power generation boiler. The bioliquid flame in the pilot furnace was clearer and more transparent, but higher gas temperature in the burner zone, compared to the heavy fuel oil flame. It might be due to higher sooting tendency of the heavy fuel oil flame. Due to the lower N and S contents in bioliquid, NOx and SOx emissions were significantly reduced in the bioliquid combustion tests. For the bioliquid demonstration in a 75 MWe power generation boiler, bioliquid firing led to decrease in heat flux to the furnace wall, so the furnace exit gas temperature was increased, comparing to the heavy fuel oil firing. Subsequently, the heat absorption in the first pass of the boiler was increased and finally it led to the increase in reheater de-superheating water spray flow rate. Significant reductions in NOx and SOx emissions were achieved with bioliquid firing. The operation and measured data in the bioliquid demonstration tests showed the successful operation of the unit, and no operational or emissions limitations were identified.