Modeling and Simulations of NO_x and SO₂ Seawater Scrubbing in Packed-Bed Columns for Marine Applications

Seawater scrubbing of nitrogen oxides and sulfur oxide from marine emissions was simulated in packed-bed columns exposed to static inclination and heaving/oscillating motions. Fourth generation random packings (Raschig super-Rings) while providing much smaller pressure drop than traditional Pall-Rings ensure comparable absorption efficiency for the pollutants. Complete removal of SO₂ was predicted over the tested pressure range with absorption efficiency indifferent to scrubber inclination or heaving/oscillating motions. In contrast, NO_x and CO₂ absorptions are negatively impacted for inclined seawater scrubbers. Removal efficiency is not lowered significantly owing to larger scrubber pressure and because diffusion of N₂O₄ into the liquid phase is associated with a rapid pseudo first-order reaction. The asymmetrical oscillating motion of the scrubber degrades the removal performance which exhibits wavy patterns close to the steady-state solution of the average inclination angle. NO and CO₂ absorption performance waves are moving toward a steady-state solution of vertical scrubber when the asymmetry of the two inclined positions of the scrubber downgrades. Symmetric oscillation and heaving motion led to performance disturbance waves around a steady-state solution of the vertical scrubber which are determined by the parameters of angular/heaving motion.