Inhibition of condensable particulate matter by co-firing biomass and high sulfur coal on a 50 kW self-sustaining combustion furnace.

Condensable particulate matter (CPM) was an important contributor to total PM emission, yet its formation and evolution during coal and biomass co-firing remained poorly understood. In this study, CPM emission from the co-combustion of high-sulfur coal and corn stover/pine wood was investigated on a 50 kW self-sustaining one-dimensional combustion furnace. The concentrations of CPM under high-sulfur coal combustion reached 6.72 mg/MJ, with inorganic components accounting for 83.3%. Corn stover and pine wood were co-fired at blending ratios of 10% and 20%. The results showed that biomass co-firing effectively inhibited CPM formation. That was, the concentrations CPM decreased to 5.09, 3.85, 5.36 and 4.55 mg/MJ for CS-10%, CS-20%, PW-10%, and PW-20%, respectively. The inhibition effect of corn stover was stronger, primarily due to the more significant decrease of sulfate-associated inorganic species and more effective suppression of organic CPM precursors. Inorganic components remained dominant under all conditions and were mainly composed of SO42- and NH4+. Organic CPM was also strongly reduced, particularly polycyclic aromatic hydrocarbons (PAHs) and sulfur-containing organic compounds, which were below the detection limit at 20% blending ratio. SEM observations further confirmed that biomass co-firing dwindled particle deposition and agglomeration on CPM collection membranes. These findings clarified the inhibition effect of biomass co-combustion on CPM generation and provided guidance for CPM control in coal-fired systems.