Study on water vapor condensation on particles' surface under high pressure for simultaneous removal of moisture and fine particles via supersonic separation

JC Xu and ZP Zhang and L Lv and ML Wang and F Li and HQ Chu, FUEL, 389, 134616 (2025).

DOI: 10.1016/j.fuel.2025.134616

Oxy-fuel combustion is one of the most promising CO2 capture technologies. However, moisture and fine particles affect the purification of CO2 from oxy-fuel combustion flue gas. This paper proposes a novel technology that simultaneously removes moisture and fine particles from oxy-fuel combustion flue gas through supersonic separation, without the need for additional consumables like adsorbents. To validate this method for CO2 capture pretreatment, molecular dynamics (MD) simulation was conducted to investigate the effects of high pressure, temperature, and particle wettability on the condensation of water molecules, which strongly influences separation efficiency. It indicates that higher pressure and lower temperature in supersonic nozzle encourage the condensation of water molecules significantly. Furthermore, there are extreme pressures and temperatures that provide maximum marginal effects to promote condensation, offering important inlet parameters for supersonic nozzle design. At higher pressures, particle wettability hardly affects the condensation rate, in contrast to under ambient pressure, where it has a substantial impact. This suggests that this technology can be used even in cases where the wettability of the fine particles generated by a particular type of coal combustion is low. Lastly, a direct observation of water molecules condense on the fine particle's surface under different pressures has been presented to further validate this innovative technology.

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