Study On The Flue Gas Desulfurization With Sodium Citrate Buffer Solution

Reducing SO2emission amount is always a hard work in China. Therefore, to investigate and develop efficient desulfurization technologies is of great significance to control the pollution of SO2. Flue gas desulfurization with sodium citrate buffer solution is a regenerative desulfurization technology with advantages such as the high efficiency of desulphurization, the recyclability of the absorption solution and the usability of the obtained SO2. This is a desulphurization method according with the idea of environment protection and the requirement of recycling economy and has been used for desulfurization of flue gas with high concentration of SO2. However, there is not a successful application of this method on the project to purify the flue gas with low concentration of SO2, and the correlational research is not sufficient.Based on the above analysis, the study on the application of citric acid-sodium citrate buffer solution on purifying the flue gas with low concentration of SO2was set as the objective of this paper. First, the single factor experiments on absorption of SO2in simulated flue gas were carried out in a packed column, so as to study the effects of parameters, such as the liquid-gas ratio, the initial pH value of absorption solution, the temperature, the concentration of sodium citrate and theinitial concentration of SO2, on the desulfurization efficiency. Then, the experiments on desorption of SO2in the rich solution were carried out in the regeneration equipment, and the effects of the temperature, the initial concentration of absorption solution, the initial pH value of absorbed solution, and the concentration of SO2of absorbed solution on desorption efficiency were studied. Moreover, the similar single factor experiments as in the packed column were carried out in a rotating packed bed (RPB), and the effects of the rotor speed in RPB, the initial pH value of absorption solution, the concentration of sodium citrate, the temperature, liquid-gas ratio and the initial concentration of SO2on desulfurization efficiency and KGa were obtained. A calculation method of KGa has been deduced.From the experimental results, optimal parameters for the process in the packed column can be found as the liquid-gas ratio of5-9L/m3, the initial concentration of sodium citrate in absorption solution of0.5mol/L, the initial pH value of absorption solution of4.0-5.0, the absorption temperature of50-60℃and the desorption temperature100～105℃. The preferred parameters for the process in the RPB can also be found as the rotor speed in RPB of1200-1400r/min, the liquid-gas ratio of8-12L/m3, the initial pH value of absorption solution of4.5-5.0and the concentration of sodium citrate in absorption solution of0.6mol/L. It was found that KGa increased with the increase of the rotor speed and liquid-gas ratio until approaching to a stable value. The Kca increased constantly with the increasing initial pH value, the concentration of absorption solution and the temperature, while was insensitive to the variation of initial concentration of SO2. A significant enhancement of KGa can be achieved via increasing the rotor speed, liquid-gas ratio, or the initial pH value of absorption solution within a certain range.