Pilot-Scale Aftertreatment Using Nonthermal Plasma Reduction of Adsorbed NOx in Marine Diesel-Engine Exhaust Gas

Abstract

Regulations governing marine diesel engine NOx emissions have recently become more stringent. As it is difficult to fulfill these requirements by combustion improvements alone, effective aftertreatment technologies are needed to achieve efficient NOx reductions. In this study, we develop an effective NOx-reduction aftertreatment system for a marine diesel engine that employs combined nonthermal plasma (NTP) and adsorption. Compared with selective catalytic reduction, the proposed technology offers the advantages of not requiring a urea solution or harmful heavy-metal catalysts and low operating temperatures of less than 150 °C. The NOx reduction comprises repeated adsorption and desorption flow processes using NTP combined with NOx adsorbents made of MnOx–CuO. High concentrations of NOx are treated by NTP after NOx adsorption and desorption, and this aftertreatment system demonstrates excellent energy efficiencies of 161 g(NO2)/kWh, which fulfills the most recent International Maritime Organization emission NOx standards in the Tier II–III regulations for 2016 and requires only 4.3 % of the engine output power.