Characteristic Study Of Fractal Structure For Desulfurization Product Of Calcium-based Sorbent

The main research of coal-cleaning combustion in power plant is controlling the emission of SO2, dry desulfurization and semi-dry desulfurization are two main methods that adopted in China to reduce the emission of SO2, but the desulfurization efficience is too low. Calcium-based sorbent is porous material in which structure is changed for the sake of sintering during high temperature reaction, so the diffusion resistance become bigger since SO2molecules flow into the pores until reaction is ceased. The main research of sorbent is analyzing and simulating the geometric parameters with the help of mathematical models.The sorbent particles of calcination and desulfurization turn into random distribution, but have a certain statistical regularity under the scanning electron microscope.SEM images of particles were obtained after calcinating the limestones at different temperatures, study showed that the fractal structure of particles were different when sorbent was calcinated under distinctive temperatures, gas escape and sintering are two main factors that affect the fractal structure of particles. Using multi-fractal theory can distinguish the merit of particle structure, the multi-fractal spectrum and generalized dimension spectrum can also quantitatively describe the uniformity and regularity of particles. Direct desulfurization and calcium oxide desulfurization were progressed under three different temperatures, finally we got kinetic parameters and particle distribution from dynamic and multi-fractal prospect, the result showed that the calcium oxide desulfurization reaction at chemical reaction phase and direct desulfurization reaction at product-layer diffusion phase were faster because the activation energy was smaller. The sulfide product of direct desulfurization was uneven and irregular because CO2was escaped and more SO2molecules came into the pores to react with sorbent, the results had an important reference to grasp the characteristic and microstructure of calcium-based sorbent.