Evaluation And Optimization Of Calcium-based Sorbents Sulfation

SO2 is one of the major air pollutants from coal-fired electric power plants, resulting in serious environmental problems. Research on S02 emission caused by coal-fired becomes more and more important. Calcium-based sorbents were widely used in SO2 control, especially in fluidized-bed combustion (CFB). More researchers focus on the problems of the performance evaluation and optimization of calcium-based sobents sulfation.Based on experimental and theoretical study, researches were carried on finding a relationship between physical and chemical properties of sorbents and their sulfur capture capability at a fluidized bed condition, and studying of effects and mechanics of metal compound additives on CaO sulfation. The result improves sorbents selection.Three types limestoned and two types seashells were chosed as SO2 sorbent. The chemical composition, pore volume, size and distribution, partical and grain size of those sorbents were measured by a atomic absorption spectrophotometer, a scanning electron microscope (SEM) and a mercury porosimeter, respectively. A bench-scale fluidized bed reactor was designed and established. Series of thermal desulphurization experiments were carried out on the reactor. The results showed that sorbents reactivity was related with various factors.Seven metal compounds were selected as additives to optimize sorbents sulfation. Research of promotion was based on different addition rate and reaction temperature. It can be concluded that all of them can increase the utilization of calcium. The promotion rate was the function of the type of additive, reaction temperature and addition rate. The mechanics analysis was based on the change of the properties of sorbents after calcination, such as apparent structure, cell parameter and pore distribution, which were measured by SEM, x-ray diffraction (XRD).Menger manifold was used to simulate the porous structure of calcined sorbents. Fractal dimension of sorbents was computed. Based on testing data obtained on mercury porosimeter analysis, Rayleigh distribution was used as the function of pore size distribution. According to bethe network percolation, the reaction between SO2 and.dry porous CaO was simulated to forecast the change of radial SO2 concentration related and porosity. Sequentially, the desulfuration model was built to pre-estimate utilization of sorbent.