Molar ratio and energy efficiency of DeNOx using an intermittent DBD ammonia radical injection system

Ammonia radicals are produced by a dielectric barrier discharge (DBD) in a chamber, called radical injector, which is separate from the chamber that NO gas flows. The radicals are injected into the mixing zone in NO gas flow field to decompose NO gas. The power source for generating the DBD is a one cycle sinusoidal (OCS) waveform so as to easily control the electrical power consumed in the DBD plasma. The fundamental frequency of the OCS power source is 150 kHz. Based on the molar ratio of ammonia particles to NO particles in a unit time, NO removal characteristics were discussed. By increasing the DBD consumed energy, the molar ratio approaches 1 showing the stoichiometric DeNO_x by NH₂ radicals. A high energy efficiency is found by reducing the consumed energy in the radical injector, where the molar ratio is higher than 1. In this case, the excess ammonia gas without converting into ammonia radicals in the radical injector is directly injected into the reaction zone, and contributes to decompose the NO gas. Oxygen gases with a concentration from 5% to 15% included in the NO gas significantly contribute to decompose NO gases, which brings a decomposition of NO with a low molar ratio.