The effect of hydrogen peroxide solution on SO2 removal in the semidry flue gas desulfurization process

The present study attempts to use hydrogen peroxide solution to humidify Ca(OH)2 particles to enhance the absorption of SO2 to achieve higher removal efficiency and to solve the valuable reuse of the reaction product in the semidry flue gas desulfurization (FGD) process. Experiments were carried out to examine the effect of various operating parameters including hydrogen peroxide solution concentration, Ca/S molar ratio and approach to adiabatic saturation temperature on SO2 removal efficiency in a laboratory scale spray reactor. The product samples were analyzed to obtain semi-quantitative measures of mineralogical composition by X-ray diffraction (XRD) with reference intensity ratio (RIR) method and the morphology of the samples was examined by scanning electron microscope (SEM). Compared with spraying water to humidify Ca(OH)2, SO2 removal efficiency was improved significantly by spraying hydrogen peroxide solution of 1-3 wt.% to humidify Ca(OH)2 because hydrogen peroxide solution enhanced the dissolution and absorption rate of SO2. Moreover, XRD and SEM analyses show that the desulfurization products contain less amount of unreacted Ca(OH)2 and more amount of stable calcium sulfate with increasing hydrogen peroxide solution concentration. Thus, the process mechanism of the enhanced absorption of SO2 by spraying hydrogen peroxide solution to humidify Ca(OH)2 was elucidated on the basis of the experimental results.