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

Abstract

The coabsorption of SO x and NO x supported by the enhanced oxidation of NO by ClO2(g) from flue gases is investigated through technical-scale experiments and simulations. In focus is NO x 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 NO x , SO x , and 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 NO x and SO x 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.

Techno-Economic Evaluation of Co-Removal of NOx and SOx Species from Flue Gases via Enhanced Oxidation of NO by ClO2—Case Studies of Implementation at a Pulp and Paper Mill, Waste-to-Heat Plant and a Cruise Ship

“…In the conceptual design the oxidation reactor is constructed of Stainless steel 304 L. The reactor should be designed to increase mixing with minimal pressure drop. It is noteworthy that results obtained in previous studies indicate that the oxidation of NO to NO 2 via ClO 2 is rapid and not dependent on an advanced mixing reactor design [16,23]. The flue gas continues to a quench where temperature decrease, and the gas becomes saturated.…”

Simultaneous Removal of NOx and SOx from Flue Gases Using ClO2: Process Scaling and Modeling Simulations

“…100 N m 3 /h Setup. The 100 N m 3 /h setup applied to the Chalmers 100 kW unit is described in greater detail in our previous work 11 and is described only briefly here. The Chalmers 100 kW unit consists of a down-fired boiler that combusts propane.…”

“…The gas- and liquid-phase chemistries of the NO–SO 2 –ClO 2 system are described in detail in our previous work, , and only the reactions that have been established as important are presented here. As discussed, ClO 2 is a powerful oxidizing agent that is suitable for the oxidation of NO to NO 2 in a flue gas system.…”

“…The modeling and chemistry used are described in more detail in our previous paper. , When modeling the 0.2 and 100 N m 3 /h setups, an open-loop simulation was run in which no recirculation occurred. Because neither of the two setups reached the steady state, the liquid compositions measured during the experiments were used as the inlet compositions in the simulations.…”

“…3−10 In our previous work, we studied the coremoval of NO x and SO x from flue gases in a wet scrubber step. 11 For the concept to work, NO, which is the dominant NO x species in combustion, needs to be oxidized to NO 2 . We have tested gaseous ClO 2 as the oxidizing agent and obtained promising results.…”