| OCR Text |
Show Oxygen is not useful for NO oxidation at flue gas conditions because their interaction is very slow and characteristic reaction times are several orders of magnitude longer than flue gas residence times in post-combustion channels. Several methods have been suggested for NO-to-N02 oxidation in flue gas. Lyon et aL (1990) described NO oxidation by injection of methanol into flue gas at 900- 1300 K. Chang and Lee (1992) found that yellow phosphorus being added into wet scrubbing systems is capable offonning ozone which subsequently converts NO to N02• U.S. DOE researchers used hydrogen-oxygen flame (Lee et al., 1989) and ultrasound (Shojaie et al., 1992) for NO oxidation. Methanol injection into flue gas is a part of the CombiNOx process (Pont et aI., 1993) which was developed by Energy and Environmental Research Corporation. CombiNOx includes a family of NOx control technologies (rebuming, urea injection, methanol injection, and wet scrubbing) capable of reducing NOx emissions by 89-96% at pilot-scale. However, it was found by Pont et al. (1993) that methanol forms CO in flue gas as a by-product, and CO is not oxidized to CO2 since the methanol injection temperature required for effective NO oxidation is relatively low. This problem may reduce potential application of the CombiNOx process. A solution for the problem would be to find another reactant which could rapidly convert NO to N02 without producing CO. Such a reactant was recently described by Zamansky et al. (1995). Hydrogen peroxide being added to simulated flue gas in a quartz reactor at residence times of 0.4-1.6 s and temperatures 700- 1100 K, was capable of converting NO to N02 and also removing some other air pollutants. Though the existence of NO-H202 interaction has been demonstrated earlier experimentally by Azuhata et al. (1982) at long residence times of approximately 12 s, this was not applicable to air pollution conn'o!' Hydrogen peroxide and H20/CH30H mixtures are capable of reacting with NO, S03' and organic compounds in combustion gases (Zaman sky, et aI., 1995). The current paper presents 2 . |
