Oxidation of NO to NO₂ with Ozone in Real Flue Gas Emitted from a Diesel Oil Combustor

¹ Techno Park, King Mongkut’s University of Technology North Bangkok, 10800 Bangkok, Thailand
² Department of Power Engineering Technology, College of Industrial Technology, King Mongkut’s University of Technology North Bangkok, 10800 Bangkok, Thailand
³ Department of Mechanical and Automotive Engineering Technology, Faculty of Engineering and Technology, King Mongkut’s University of Technology North Bangkok, (Rayong Campus), 21120 Rayong, Thailand
⁴ Research Centre for Combustion Technology and Alternative Energy (CTAE), King Mongkut’s University of Technology North Bangkok, 10800 Bangkok, Thailand

^* Corresponding author: sak.s@cit.kmutnb.ac.th

Abstract

To reduce nitrogen oxides emissions (NOx) from flue gas, selective catalytic reduction (SCR) or adsorption using various solution are efficient methods. However, nitric oxide (NO) needs to be oxidised into nitrogen dioxide (NO₂) to enhance NOx removal performance. This paper presents the effects of operating parameter of a dielectric barrier discharge (DBD) reactor on ozone (O₃) generation which ozone was utilised to oxidise NO into NO₂ in the real flue gas from diesel oil burner. A cylindrical DBD configuration with 1.5 mm electrode gap and effective discharge volume ranged from 13.8 cm³ were chosen to produce O₃-rich air for oxidising NO. Using concentrated O₂ instead of air as O₃ source could enhance O₃ formation (8.57 g/kWh vs. 44.08 g/kWh). NO conversion to NO₂ by O₃ was strongly dependent on O₃/NO ratio. Additionally, thermal O₃ decomposition by heat energy in flue gas also substantially reduced O₃ which must be compensated by using excess O₃/NO ratio. At flue gas temperature of 407°C, O₃/NO ratio of 6.37 was required to complete oxidise NO into NO₂. The optimal NO conversion efficiency of 2.93 g/kWh was realised at flue gas resident time of 313 ms and flue gas temperature of 483°C.