CFD analysis of combustion characteristics for fuel switching to bioliquid in oil-fired power plant

Abstract

Complete fuel switching from heavy fuel oil (HFO) to bioliquid (BL) was demonstrated in a 100MWe-capacity boiler with a tangential firing configuration. The BL from the residue of palm oil production successfully replaced HFO at the full load (103MWe) with new atomizers and minor adjustments to the operating parameters. The detailed combustion and heat transfer characteristics of the two fuels were analyzed using computational fluid dynamics (CFD). Compared to the HFO firing case, more uniform distributions of the gas temperature and heat transfer rate were observed in the combustion zone for the BL firing case. The total heat transfer rate was slightly lower on the furnace wall (evaporator), but this disadvantage was offset by the increased convection in the downstream heat exchangers. Because of the low soot concentration, the contribution of convection in the BL-firing case was larger in the lower furnace. A significant reduction in SOx and NOx emissions was achieved due to the low S and N content of BL, which would be the main benefit of fuel switching, in addition to the minimization of greenhouse gas emissions. In the future, the CFD model established in this study could be applied to the evaluation of BL different candidates and various co-firing cases with HFO.