Simultaneous Removal of NO_x and SO_x from Flue Gases Using ClO₂: Process Scaling and Modeling Simulations

Abstract

The concept of coabsorption of NO2 and SO2 from flue gases, in combination with the enhanced oxidation of NO by ClO2(g), is studied on three scales, 0.2, 100, and 400 N m3/h, all with flue gases of different origins. The results obtained from each setup are presented, together with modeling that was applied to assess the scale-up of the concept and to validate the model. The measurements confirm that ClO2 is highly selective toward NO oxidation for temperatures in the range of 70–155 °C. A comparison of the results obtained for each scale reveals that the 0.2 N m3/h setup confers a higher level of NO x absorption than the other setups, although the trends remain similar. Simulations of the results underpredict the level of NO2 absorption in the 0.2 N m3/h setup while capturing the levels of absorption in the 100 N m3/h setup. An important finding is the rapid and complete oxidation of S­(IV) in the presence of NO2, which is not represented in the reaction kinetics.

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

“…Three cases: a small sized waste-to-heat plant, a cruise ship and a kraft recovery boiler of a medium-sized pulp and paper mill, are identified as potential targets for the technology where either process conditions or existing facilities make for an interesting business case. Based on previous experiments, a simple process setup is established for each investigated case [7]. Each case process setup is simulated using a detailed reaction mechanism.…”

“…Techno-economic evaluation of simultaneous removal of NO x and SO x from flue gases were performed for three applications: a medium-sized waste-to-heat plant (20 megawatt, MW); a medium-sized pulp and paper mill (500,000 tons pulp/year) recovery boiler; and a cruise ship (12 MW). The technical performance of each case was investigated through simulations based on previous experimental results [7]. Economic evaluations were then performed based on the technical study.…”

“…In this study ClO 2 was used in the oxidation step due to the previous research on ClO 2 by our group that shows high efficiency in a lower temperature range and simple process integration of the oxidation [7]. However, it should be noted that all aforementioned oxidation chemicals appear to be viable options and depending on regional legislations, site facilities and flue gas temperatures, one oxidizing agent might be favored above the others.…”

“…Our research group studied the combined absorption of NO x and SO x from the flue gases of a waste incineration plant using gaseous chlorine dioxide (ClO 2 ) to oxidize NO to NO 2 . It was shown that >90% of the SO x and >80% of the NO x can be removed using NaOH and Na 2 SO 3 as scrubber additives [7]. Meng removal of NO x and SO x from a simulated flue gas using ozone (O 3 ) to oxidize NO.…”

Recirculation of NOx and SOx Scrubber Effluent to an Industrial Grate Fired MSW Boiler─Influence on Combustion Performance, Deposition Behavior, and Flue Gas Composition

“…As mentioned, the scrubber effluents were collected during a previous campaign where a slip stream of the flue gas passed through a mobile pilot plant for NO oxidation with ClO 2 and subsequent scrubbing of NO x and SO x . 2 Around 3 m 3 of the Energy & Fuels scrubber effluent was accumulated from each campaign. The batches have different compositions due to the differences in scrubber operation.…”