[Objective] In the current energy landscape

the implementation of deep peak shaving in coal-fired thermal power units has transitioned low-load operation from a transient state to a long-term operational norm. This shift poses a significant technical challenge: the flue gas temperature within the rotary air preheater frequently drops below the acid dew point

leading to the intensive formation and condensation of ammonium bisulfates(ABS). The presence of ABS

characterized by its high viscosity and corrosive nature

significantly exacerbates the adhesion of fly ash

resulting in severe blockage and fouling of the heat transfer surfaces at the cold end. Despite its prevalence

the industry currently lacks an effective and systematic solution to mitigate this fouling. Therefore

this study aims to provide an in-depth exploration and microscopic observation of the adhesion and deposition characteristics of ABS-coated fly ash particles under varying low-load operational parameters. [Methods] To accurately capture the complex interaction between particles and the heating elements

this research refined the conventional particle elasticity theories by incorporating the cohesive energy effects of liquid-bridge forces. A sophisticated and novel “deposition-detachment” mathematical model was constructed to simulate the dynamic equilibrium of particle capture. Utilizing this advanced model

the study systematically investigated the deposition kinetics of ABSadherent fly ash on the corrugated regenerative plates of the air preheater. Furthermore

through high-fidelity numerical simulations

the research quantitatively explored the sensitivity of the internal temperature distribution

localized pressure fields

and the spatio-temporal particle deposition trajectories to fluctuations in the boiler's generation load. [Results] The findings indicate that the proposed deposition-detachment model provides superior observational accuracy regarding particle deposition within the air preheater compared to conventional models. The accumulation of ABS-adherent particles on the regenerative plates demonstrates a progressive increase over time

characterized by a “fluctuating upward” trend. Under identical operating conditions

the deposition volume of smalldiameter particles(ranging from 1 μm to 70 μm) was found to be 64 times greater than that of larger particles(180～200 μm)

highlighting the sensitivity of fine particulate matter to ABS-induced adhesion. Moreover

the reduction in unit load triggers significant shifts in the thermal and hydraulic fields; for every 10% decrease in load

the overall flue gas temperature drops by approximately 7.7 K

while the pressure differential between the inlet and outlet increases by roughly 8.12 Pa. [Conclusion] Low-load operation of thermal power units significantly intensifies the ash fouling problem on the cold-end heating surfaces of air preheaters. The deposition regularities and the evolution of temperature and pressure fields revealed in this study provide a critical theoretical foundation for elucidating the mechanisms behind frequent air preheater blockages. Furthermore

these insights offer essential technical guidance for implementing precision soot-blowing operations in industrial engineering applications.