Scrubber tower

A scrubber tower is the absorber vessel of a marine exhaust gas cleaning system (EGCS), where engine and boiler exhaust is sprayed with alkaline wash water to remove sulfur oxides. It lets a ship burn high-sulfur fuel oil while meeting MARPOL Annex VI Reg 14, which caps fuel sulfur at 0.50% globally and 0.10% in emission control areas; a scrubber is an approved equivalent. Open-loop towers use seawater alkalinity and discharge wash water overboard, closed-loop towers recirculate caustic-dosed fresh water and hold a small bleed, and hybrid towers switch between modes. Many ports restrict open-loop discharge.