Coal Combustion Dynamics in Oxy-Fuel Environments

Coal combustion dynamics under oxy-fuel conditions are distinguished by the use of high-purity oxygen and flue-gas recirculation to create a CO₂-rich atmosphere aimed at facilitating carbon capture. In this environment, fundamental processes including ignition, devolatilisation, char oxidation and particle fragmentation manifest differently from air combustion. The elevated CO₂ concentration increases the heat capacity of the bulk gas, leading to modified flame temperatures and slower reaction kinetics. Radiative heat transfer is altered by the increased opacity and emissivity of CO₂-rich mixtures, thus influencing the heat feedback to fuel particles. Coal particles undergo pyrolysis to release volatiles, form chars that subsequently oxidise, and may fragment or spheroidise under thermal stress. The resulting combustion behaviour impacts flame stability, pollutant formation and boiler performance. Advanced diagnostic techniques, from high-speed imaging in drop-tube furnaces to laminar-flow reactors, have elucidated the roles of particle size, number density and gas composition. Computational models, ranging from single-particle kinetics to CFD simulations of full-scale furnaces, integrate these insights to predict performance and guide retrofitting strategies. By understanding these dynamics, oxy-fuel combustion can be optimised for low-carbon power generation and integrated with biomass co-firing for further CO₂ reduction.

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Coal Combustion Dynamics in Oxy-Fuel Environments publication trend

The graph below shows the total number of articles in coal combustion dynamics in oxy-fuel environments across all publications each year (not limited to Nature Index journals).

Technical terms

Oxy-fuel combustion: Combustion using pure or enriched oxygen with recycled CO₂ instead of air to produce a CO₂-rich flue gas for capture.

Ignition delay time: Interval between exposure of a fuel particle to a reactive atmosphere and the onset of stable combustion.

Devolatilisation: Release of volatile compounds from coal particles upon heating, preceding char formation and oxidation.

Char burnout: Oxidation of the residual carbonaceous material after devolatilisation, leading to complete fuel conversion.

Particle number density: Number of fuel particles per unit volume, which affects radiative heat transfer and flame structure.

Radiative heat transfer: Energy exchange through electromagnetic radiation, significant in high-temperature, CO₂-rich flames.

References

1. Particle-resolved optical diagnostics of solid fuel combustion for clean power generation: a review. Measurement Science and Technology (2023).
2. Combustion Characteristics of Single Particles from Bituminous Coal and Pine Sawdust in O2/N2, O2/CO2, and O2/H2O Atmospheres. Energies (2017).
3. Combustion of single walnut shell particles in a laminar flow reactor under oxy-fuel conditions: Optical measurements and particle sampling. Fuel (2024).
4. Combustion behavior profiling of single pulverized coal particles in a drop tube furnace through high-speed imaging and image analysis. Experimental Thermal and Fluid Science (2017).