Total Emission Control for Multi-Fuel Boiler System with Plasma-Chemical Aftertreatment

H. Fujishima1, Y. Fukumoto1, T. Kuroki1, A. Tanaka2, K. Otsuka2, and M. Okubo1

1Department of Mechanical Engineering, Osaka Prefecture University, Japan
2Department of Engineering, Takao Iron Works Co., Japan

Abstract- A low-emission boiler system that consists of a multi-fuel boiler for hot water or steam supply and a plasma-chemical hybrid NOx removal apparatus is demonstrated. The boiler has a 2.5 t/h steam generation rate. Many experiments are conducted using fuel gas and oils at flue gas flow rates between 550 to 2250 Nm3/h (N: 0oC, one pressure). Operational characteristics are investigated in order to achieve stable continuous system operation. Ozone injection for NO oxidation and a Na2SO3 solution for NO2 reduction are essential factors of the hybrid NOx removal system. The effect of operational parameters on NOx removal characteristics are obtained, such as O3 injection method, Na2SO3 supply rate, and the flow rate correlation between the Na2SO3 solution, fresh water, and drainage. An operation of four successive days is satisfactorily carried out, maintaining a stable NOx removal efficiency of more than 85%. This low-emission boiler system can be used in industry.

Keywords- Nonthermal plasma, chemical process, multi-fuel boiler, NOx and SOx treatment, ozone, Na2SO3.



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