Influence of Key Factors on the Characteristics of Flue Gas Desulfurization of Basic Aluminum Sulfate by Bubbles

Temperature, reactant concentration, bubble flow field characteristics, and mass-transfer characteristics play an important role in flue gas desulfurization of basic aluminum sulfate (aluminum base). The influence of various factors on desulfurization efficiency (η abs ) was determined from the macroscopic and microscopic levels through experiments and numerical simulations. The temperature of absorption solution had a significant effect on η abs , and low temperature was advantageous for SO 2 absorption performance of aluminum base. The value of η abs increased with increasing reactant concentration. When the aluminum base concentration was higher than 50%, η abs remained above 90%. The low aluminum base shortened the beginning time of the rapid decline of η abs . This outcome was related to the low concentration of active Al 2 O 3 . At a low concentration range of 2000-5000 ppm of inlet SO 2 , the reaction rate determined the η abs level, and gas-phase mass-transfer resistance was the main factor restricting the increase in η abs . However, reaction rate and gas-phase mass-transfer resistance determined the η abs level when the inlet SO 2 concentration was as high as 50 000 ppm. The aeration rate affected the bubble size, number, and diffusion state. In addition, a higher aeration rate reduced the gas-liquid contact time and speeded up the consumption of aluminum base. As a result, bubbles along the absorber height showed different desulfurization characteristics, that is, 0-0.1 m was the initial stage of bubble formation and desulfurization (the η abs was lower than 15%), 0.1-0.34 m was the main stage of bubble diffusion and desulfurization (the η abs rapidly increased to 86.4%), and 0.34-0.4 m was the stable stage of desulfurization (the η abs slowly increased to 92.5%).