Computer simulation of NOx removal from diesel engine off-gases under electron beam and wet scrubber system

Abstract

NOx emission from diesel engine off-gases in marine transportation sector is still an environmental issue to be solved in present day. Electron beam (EB) followed by a seawater wet scrubber method to removal NOx has been experimentally studied (Chmielewski et al., 2018). In this work numerical simulation of NOx reduction using EB followed by a water scrubber system has been carried out. The first stage was to calculate NOx removal versus dose under EB irradiation. Computer code “KINETIC” and Gear method were used, the model has been improved based our previous work (Zwolinska E. et al., 2015) and verified by the experimental results. The calculation results of NOx removal efficiency was 4.9% at 10.9 kGy dose under EB irradiation, which was a little higher than experimental value (3.5%). Computer program MATLAB was used to study NOx absorption in water. The NOx removal efficiency was increased by 17.5% at 10.9 kGy dose for inlet concentration of NOx being 1333 ppm after EB-water absorption process. At the end, NOx reduction in the simulated marine off-gas using microwave plasma was simulated using computer program Chemical Workbench. Less than 20% NOx was removed from the off-gases in microwave plasma reactor even at 9000 kGy dose for the inlet concentration of NOx being 1500 ppm. EB is more energy efficient than microwave plasma for NOx removal.