Evaluation of physicochemical properties and combustion behavior of biomass refuse-derived fuel

Abstract

Recently, a 125 MW biomass power plant in South Korea has been operating annually using 600,000 tons of wood pellets as fuel, producing approximately 6,000 tons of biomass refuse-derived fuel (BRDF) each year. Owing to challenges in pulverizing biomass, large particles are introduced into the boiler furnace during power generation. However, their size hinders complete combustion, and approximately 1.0 % of the fuel input to the boiler descends to the bottom and is subsequently collected in the ash hopper; it corresponds to BRDF. This study evaluated the recyclability and applicability of BRDF in boilers by comparing its fuel properties with those of raw wood pellets (RWP), torrefied wood pellets (TWP), and coal. Furthermore, we analyzed and assessed the physicochemical properties and fundamental combustion characteristics using the thermally treated biomass grindability index (TTBGI), Fourier-transform infrared spectroscopy (FT-IR), and thermogravimetric analysis (TGA). The fixed carbon content of BRDF increased, whereas the volatile matter content decreased compared with that of RWP. The H/C and O/C atomic ratios of BRDF were similar to those of coal, and the higher heating value (HHV) of BRDF was improved compared with the other samples. Scanning electron microscopy (SEM) images confirmed significant pore development in the BRDF, and BET analysis indicated an increase in the specific surface area. The TTBGI measurements indicated improved grindability of the BRDF and increased lignin content. In particular, Cmean (%/min) and Cmax (%/min) increased compared with RWP, and the combustion characteristics of the BRDF improved. Therefore, this study suggests that BRDF has the potential to be utilized as a fuel in existing boilers.