Kinetics of oxidation of total sulfite in the ammonia-based wet flue gas desulfurization process

摘要

Using bubbling apparatus, the kinetics of oxidation of total sulfite in ammonia-based wet flue gas desulfurization (FGD) process was investigated by varying concentrations of SO3~(2-) and SO4~(2-), pH, temperatures and air flow. The concentration range of sulfite is 0.0044-0.026 gmol L~(-1) and that of sulfate is 0.5-2 gmol L~(-1). Experiments were conducted at pH level of 4.5-6.5 and air flow ranging from 50 to 200 L h~(-1). In the temperature range of 303.15-333.15 K, the reaction was found to be -0.5 order with respect to sulfite. The experimental findings also showed that the bisulfite could be oxidized easier than sulfite. Thus, keeping the pH level of the solution low is conducive to the oxidation of total sulfite. The apparent activation energy for the overall oxidation was calculated to be 28.0 kJ mol~(-1). A kinetic model has been derived according to the experimental results. The developed kinetic model, including the operating parameters SO3~(2-) concentration, SO4~(2-) concentration, pH, temperature and air flow, can be applied to simulate the oxidation of total sulfite. This model would be useful for the design of the ammonia-based wet FGD system.