Controlling emissions from an ocean-going container vessel with a wet scrubber system

Abstract

This study assessed the real-world gaseous and particulate emissions for a wet scrubber retrofit to an existing container ocean-going vessel as it cruised from Tacoma Washington to Anchorage Alaska. The vessel was operated with a high sulfur heavy fuel oil and testing was performed following the ISI 8178 E2 steady test cycle. The scrubber unit provided more than a 95% removal efficiency of sulfur dioxide (SO2) emissions across all engine loads. In contrast to the higher removal efficiencies for SO2 emissions, the scrubber only removed approximately 10% (ISO weighted reduction) of particulate matter (PM2.5) emissions. PM2.5 composition was primarily composed of sulfate, followed by organic carbon (OC) and elemental carbon (EC). Pre- and post-scrubber sulfate levels were similar, indicating why the PM2.5 removal efficiencies were low. This phenomenon was likely due to the formation of small sulfuric acid particles in the scrubber fluid that were not efficiently removed by impaction, influencing PM2.5 mass emission measurements.