Non-LTE time-dependent plasma chemistry model of E-beam NOx remediation from surrogate flue gas mixtures

We have developed a non-equilibrium time-dependent plasma chemistry model to describe NOx remediation from flue gas (82% N2, 6% O2, and 12% CO2) using the NRL Electra e-beam facility. Currently, this is a single shot model, in which the pulse width varies between 70 ns to 1.5 μs and the power deposition vary from 0.005 J/cm3 to 0.5 J/cm3. During the e-beam irradiation, the energetic electrons generate chemically active species, which then react with NOx to form harmless substances. The created plasma strongly deviates from thermodynamic equilibrium: after the beam is terminated a new equilibrium state is established in which the NOx amount have been substantially reduced. The relaxation process is due to a large number of plasmo-chemical reactions and proceeds on a time-scale from nanoseconds to tens of seconds. It was found that short (ns) e-beam pulses are the most efficient for NOx removal. Removal efficiency over 95% NOx with initial concentration of 200–1000 ppm range in a balance of 1.16 atm N2 was achieved [1]. In a simulated flue mixture at 1.2 atm, the initial 100 ppm NOx content has been reduced below the required level of EPA regulations [2]. Additional study is required on NOx reduction at elevated temperatures (> 500 C) and increased water vapor concentration.