Combustion behavior and pollutant emissions of the pressurized fluidized bed oxy-fuel co-firing of coal and poultry manure

Pressurized oxy-fuel combustion is a next-generation and low-cost carbon capture technology with industrial application potential. This work presents an innovative research exploration—coupling coal pressurized fluidized bed oxy-fuel combustion technology with energy utilization of poultry manure as a renewable and carbon-neutral fuel, in order to capture CO₂ and solve the problem of poultry manure treatment simultaneously. In this study, a stable co-combustion of coal and chicken manure in a laboratory-scale pressurized fluidized bed under typical oxy-fuel condition (30%O₂/70%CO₂, i.e., Oxy-30) is achieved. The key parameters including the combustion pressure (0.1–0.5 MPa) and chicken-manure proportion (0% to 100%) and their impacts on fundamental combustion efficiency, carbon conversion, nitrogen and sulfur pollutant emissions, and residue ash characteristics have been investigated. The result show that pressurization favors an increase in the CO₂ enrichment concentration and fluidized bed combustion efficiency. During co-combustion under 0.1 and 0.3 MPa, the CO₂ concentration in the flue gas is the highest when the chicken manure blending ratio (M_pm) is 25%. Although the NO emissions fluctuate and even increase as M_pm increases, the co-combustion of coal and chicken manure exhibits a synergistic effect in reducing NO conversion rate (X_NO). The effect of pressurization on reducing NO emission is significant, X_NO at M_pm = 25% decreasing from 15% to 5% as the pressure (P) increases from 0.1 to 0.5 MPa. As P increases from 0.1 to 0.5 MPa and M_pm increases from 0% to 50%, the SO₂ emissions and conversion rates decrease. The self-desulfurization process plays an important role in the reduction of SO₂ emissions during pressurized oxy-fuel co-combustion. The aim of this work is to advance the development and application of pressurized fluidized bed oxy-fuel co-combustion technology and promote a circular bioeconomy and carbon-free waste management for biomass derived from livestock manure.