Experimental Study on the Effect of H2O Concentration on the Degradation of Sulfur Hexafluoride by Two-Stage Tandem DBD

SF₆ is a greenhouse gas widely used in the power industry that cannot be directly emitted. This study employs a self-designed two-stage dielectric barrier discharge (DBD) plasma series method that was used to degrade SF₆ gas and analyzes the effect of H₂O concentration. The results indicate that the SF₆ degradation rate (DR) initially increased and then decreased with the rise in the water vapor content. When the added H₂O concentration increased from 0.5 to 1.5%, the degradation rate of SF₆ increased from 89.49 to 100%, achieving complete degradation of SF₆. However, when the H₂O concentration further increases to 2.5%, the degradation rate of SF₆ decreased to 92.83%. The energy efficiency of SF₆ degradation in the primary reaction system first increased and then decreased with the increase of H₂O concentration, while that of SF₆ in the secondary reaction system first decreased and then increased. It was found that the products of SF₆ were SO₂F₂, SO₂, SOF₂, and SOF₄. The addition of H₂O increased the selectivity of SO₂ in the decomposition products to 75.17%, and inhibit the formation of SO₂F₂ and SOF₂. This study provides experimental support for the degradation of SF₆ waste gas and provides a research direction for its industrial application.