Oxidation of NO to NO2 by Hydrogen Peroxide and Its Mixtures with Methanol in Natural Gas and Coal Combustion Gases

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OXIDATION OF NO TO N02 BY HYDROGEN PEROXIDE AND ITS MIXTURES WITH METHANOL IN NATURAL GAS AND COAL COMBUSTION GASES Vladimir M. Zamansky*, Loc Ho, Peter M. Maly and W. Randall Seeker Energy and Environmental Research Corporation ABSTRACT 18 Mason, Irvine, CA 92718 Phone: [phone]; fax: [phone] E-mail: [e-mail] -- I The CombiNOx process includes a family of NOx control technologies (rebuming, urea injection, methanol injection, and wet scrubbing) capable of reducing NOx emissions from stationary combustion sources by about 90%. However, methanol forms CO in flue gas as a by-product. Hydrogen peroxide and H20/CH30H mixtures decrease the amount of CO formed from CH30H and can substitute methanol in the CombiNOx process. This paper presents experimental and modeling results on H20 2 and H20iCH30H reactions with NO in a 300 kW combustor filing natural gas and coal. Maximum NO oxidation was achieved at 750-820 K for injection of H20 2 and a 1: 1 H20jCH30H mixture, and at 850-930 K for CH30H injection. NO-to-N02 conversion of 90-98% and 64-76% was achieved at an additivelNO molar ratio of 1.5 during natural gas and coal firing, respectively. Influence of initial NO concentrations, the additivelNO ratio, oxygen and S02 concentrations, and the presence of fly ash on process pelfonnance is discussed. Experimental results are qualitatively explained by kinetic modeling. This paper is accepted for publication in Combustion Science and Technology. INTRODUCTION Traditional methods for removal of nitrogen oxides (NOx = NO + N02) from combustion gases include moclifications of the combustion process, reburning, and Selective Catalytic Reduction (SCR) and Selective Non-Catalytic Reduction (SNCR). One of the promising NOx control strategies is conversion of NO into NO:! followed by simultaneous scrubbing of N02 and S02 from flue gas. Since nitrogen dioxide is much more reactive than NO and paltially soluble in water, N02 can be removed in alkali- or ammonium-based solutions (Kyllonen, 1970; Senjo and Kobayashi, 1977), in calcium-based wet and dry S02 scrubbers (Zalnansky et aI., 1993; O'Dowd et aI., 1994) or in other organic and inorganic solutions (Kobayashi, 1977). A large number of wet and dry scrubbers are already in place or planned for the neal' future, and a process that prolnotes NOx removal simply through the addition of a chemical additive could have a significant impact on NOx control strategies. * C orrespondillg author