Towards a comprehensive understanding of PM1 formation in pressurized oxy-fuel combustion: A study comparing model predictions with experimental data

Abstract

Oxy-fuel combustion is pivotal for fossil fuel power plants to attain net zero carbon emissions. While atmospheric pressure oxy-fuel combustion has garnered significant attention, its economic feasibility is questionable. This has led to the proposition of pressurized oxy-fuel combustion as a more economically viable alternative. A critical aspect, the formation of submicron ash aerosols (PM1), has implications for ash deposition in boilers and presents environmental concerns. Despite its significance, limited research exists on PM1 formation in this context. This study introduces a robust model, partitioned into combustion, vaporization, nucleation and condensation, and coagulation sub-models, to predict PM1 formation in pressurized oxy-fuel combustion. Key findings include: 1) Pressure escalation from 0.1 MPa to 1.5 MPa inhibits the CO formation and further reduces mineral vaporization ratio from 2.30 % to 0.12 %. 2) Elevated pressures decrease the critical nucleation diameter to about 5 nm, 4 nm, and 3 nm for pressures of 0.1 MPa, 0.8 MPa, and 1.5 MPa, respectively. 3) Coagulation primarily occurs within the diffusion layer around fuel particles, with its thickness diminishing as pressure increases. The model's predictions align closely with existing experimental data, underscoring its utility in understanding ash behavior in pressurized oxy-fuel combustion. Furthermore, this study not only bridges the knowledge gap in the field but also offers industry stakeholders a valuable tool to optimize combustion processes, mitigate environmental risks, and drive the transition towards more sustainable fossil fuel utilization.