Homogeneous oxidation of SO₂ in the tail gas incinerator of sulfur recovery unit

The formation and emission of sulfur trioxide (SO₃) in sulfur recovery unit has received increasing attention due to its adverse effects on the operation of plant and environment. Due to the excess oxygen, high concentration of SO₂ and high temperature, SO₃ formation in the sulfur recovery unit tail gas incinerator may significantly increase. A small horizontal tube reactor was employed to simulate the homogeneous oxidation of SO₂ in the tail gas incinerator. The SO₃ concentration was measured with a controlled condensation method at the outlet of the reactor. The present work focuses on the gas-phase chemistry and examines the impact of different combustion parameters and atmospheres on the formation of SO₃ in the tail gas incinerator. Experiment results show that the increased O₂ and SO₂ concentrations along with increasing temperature are favorable for enhancing SO₃ formation over the range of tested parameters. The presence of water vapor has an enhancing effect of SO₂ oxidation in the experiments conducted. No significant effect of CO₂ was found to the oxidation of SO₂.