Numerical Analysis of Burner Position and EFB-Coal Co-Firing Effects on Combustion Performance and Emissions in Pulverized Coal Boilers

Abstract

The co-firing of renewable biomass fuels, such as oil palm empty fruit bunches (EFB), with low-rank coal (LRC) in pulverized coal boilers, has emerged as a promising strategy for reducing carbon emissions while utilizing agricultural waste. This study investigates the effects of burner injection position and fuel composition on combustion performance through comprehensive computational fluid dynamics (CFD) simulations of a 315 MWe pulverized coal boiler. The research focuses on comparing EFB injection between the lower (Burner A) and upper (Burner D) burner zones at co-firing ratios of 5%, 15%, and 25% on a thermal basis. Numerical simulations were conducted using Reynolds-Averaged Navier-Stokes (RANS) equations, along with species transport and discrete phase models. Key parameters analyzed include temperature distribution, CO2 mass fraction, and NOx/SO2 emissions. The results demonstrate that EFB injection at Burner D generates significantly higher temperature increases (54.82 K at 5% EFB and 85.36 K at 25% EFB) compared to Burner A (9.74 K at 5% EFB and 34.10 K at 25% EFB). Emission analysis indicates that all co-firing scenarios result in reduced CO2 and NOx emissions compared to pure coal combustion, with maximum reductions occurring at a 25% EFB loading. Notably, the configuration of Burner A demonstrates superior emission reduction performance, even though it achieves lower temperature gains. The study concludes that the injection from the upper burner (D) enhances combustion efficiency, while the positioning of the lower burner (A) offers better emission control. A 25% EFB co-firing ratio is identified as optimal for balancing temperature maintenance and emission reduction. These findings provide critical insights for optimizing biomass co-firing configurations in coal-fired power plants.