关键词: 氧化, 动力学, Hatta数, NaCl, 反馈调节

Abstract: The efficiency of sulfite oxidation is a key factor affecting system performance in wet flue gas desulfurization (WFGD) of coal-fired power plants. However, current WFGD systems lack accurate indicators for controlling the sulfite oxidation process. To clarify the principles and methods of oxidation control, and to understand how high-salinity environments influence system oxidation states, this study employed a bubble column reactor to investigate the oxidation of calcium sulfite. From the perspective of reactive absorption and mass transfer kinetics, the study proposed the Hatta number (Ha) as a viable indicator for regulating oxidation states. The forced oxidation of sulfites by air was actually a process in which O2 was transferred from the gas phase to the liquid phase and reacts with sulfites. To analyze the characteristics of Ha in the reactive absorption system of O2, the study first evaluated physical mass transfer coefficients of O2 under varying air flow rates and NaCl concentrations. The reaction order between SO_3^(2-) and O2 was determined to be 0.863, with a reaction rate constant of 3.164. A normalized analysis under saline conditions was conducted to explore four key physical parameters (liquid diffusivity D, ion activity coefficient γ, gas-liquid contact area α, and saturated dissolved oxygen mass concentration DO*). The results showed that the ion activity coefficient is the primary pathway through which NaCl addition interferes with Ha. Based on the three-stage mechanism of reactive absorption, a feedback control strategy using Ha as the core indicator was proposed. This strategy enabled simultaneous assessment of oxidation status and dynamic adjustment of blower air volume. When implemented in the experimental system, the strategy increased O2 utilization by a factor of 5.76, and the time to reach 95% sulfite oxidation was only delayed by 200 seconds.

Key words: oxidation, kinetics, Hatta number, NaCl, feedback regulation