Fluid Bed Studies of the Limestone Based Flue Gas Desulfurization Process

摘要

It was found that the use of coarsely ground limestone and dolomite could not provide high sorbent utilization, even when the coarse particles were calcined under conditions chosen especially to produce porous materials. Only the oxide at or near the surface was observed to react, suggesting that the diffusion of SO2 through the sulfated shell or into the pores of the sorbent was limiting sorbent utilization. Consequently, additional studies were made using fluidizing conditions selected to promote attrition of the outer sulfated surface as it formed. It was felt that this might provide a continuous method of removing this surface thereby exposing reactive oxide for further reaction. This technique, however, proved unsuccessful since the sulfated surface was found to be harder than the unreacted oxide core. As a result, the fluidized particles decrepitated in their entirety to produce fines of the same composition as the coarse sorbent from which they had formed. To demonstrate high oxide utilization, the use of finely ground sorbent was next evaluated in the program. Using material sized to 100 microns or less, sorbent utilization of 60 to 80% was obtained under conditions which provided nearly complete SO2 removal. The preliminary evaluation of such a fine-particle fluid bed process, however, indicated it to be expensive (about $2/ton coal burned) and of questionable operability. (Author)