Simultaneous Removal of SO2 and Trace SeO2 from Flue Gas: Effect of SO2 on Selenium Capture and Kinetics Study

Abstract

Sulfur dioxide (SO₂) and trace elements are all pollutants derived from coal combustion. This study relates to the simultaneous removal of SO₂ and trace selenium dioxide (SeO₂) from flue gas by calcium oxide (CaO) adsorption in the moderate temperature range, especially the effect of SO₂ presence on selenium capture. Experiments performed on a thermogravimetric analyzer (TGA) can reach the following conclusions. When the CaO conversion is relatively low and the reaction rate is controlled by chemical kinetics, the SO₂ presence does not affect the selenium capture. When the 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 the selenium capture. On the basis of the kinetics study, a method to estimate the trace selenium removal efficiency using kinetic parameters and the sulfur removal efficiency is developed.