Feasibility study on simultaneous removal of sulfur and trace selenium in the MTD-FGD reactor

Abstract

This study deals with the simultaneous removal of sulfur dioxide (SO2) and trace selenium dioxide (SeO2) from flue gas by calcium oxide (CaO) adsorption in the moderate temperature range, especially the feasibility of simultaneous removal of these two pollutants in a moderate temperature dry flue gas desulfurization (MTD-FGD) reactor. The effect of SO2 presence on selenium capture is studied through the experiments performed on a thermogravimetric analyzer (TGA) and the following conclusions can be obtained. When CaO conversion is relatively low and the reaction rate is controlled by chemical reaction kinetics, the SO2 presence does not affect selenium capture. When CaO conversion is very high and the reaction rate is controlled by product layer diffusion, the SO2 presence and the product layer diffusion resistance jointly reduce selenium capture. Through analyses of some pilot scale MTD-FGD tests, it can be concluded that in the MTD-FGD reactor, the sulfate reaction of sorbent particles is generally kinetically controlled. Therefore, it is feasible that sulfur and trace selenium can be simultaneously removed by Ca-based sorbent in the MTD-FGD reactor.