Technical-Scale Evaluation of Scrubber-Based, Co-Removal of NOx and SOx Species from Flue Gases via Gas-Phase Oxidation

Abstract

The co-absorption of SOx and NOx supported by the enhanced oxidation of NO by ClO2(g) from flue gases is investigated through technical-scale experiments and simulations. In focus is NOx absorption and the oxidation of S(IV) to S(VI). The concept was tested using the flue gases from a 100-kW gas-fired furnace, to confirm findings previously obtained at the technical scale. The chemical interactions that occurred between NOx, SOx and the ClO2, used as an oxidizing agent were investigated. The measurements confirm that the absorption of SO2 in the scrubber is efficient and mainly determined by saturation in the scrubber liquid. The absorption of NO2 peaked at 82% when Na2SO3 and Na2CO3 were added to the scrubber liquid. The results indicate that the efficiencies of removal of NOx and SOx can be high (>90% and >99%, respectively). This work provides a first proof-of-concept on a technical scale and validates the reaction mechanism proposed in previous studies.