Large Volume Inorganic Chemicals - Ammonia ... - ammk-rks.net

Chapter 33.4.6 Catalytic N 2 O decomposition in the oxidation reactorDescriptionN 2 O can be decomposed just after being formed, by a selective De-N 2 O catalyst in the hightemperature zone (between 800 and 950 ºC). This is realised by placing the catalyst right belowthe platinum gauze. Most nitric acid burners are fitted with a basket filled with Raschig ringsgiving structural support to the gauzes, and the De-N 2 O catalyst can be introduced by partialreplacement of the Raschig rings. Hence, usually, no modification of the basket is required andthe gauze pack can be installed as usual.According to [109, Lenoir, 2006], a catalyst layer of 50 – 200 mm achieves a highdecomposition rate with low additional pressure drop. However, with increasing oxidationpressure, the pressure drop over the catalyst will increase.NH 3airPlatinum gauze packN 2 O decomposition catalystHeatrecoveryTo absorberFigure 3.9: Catalytic N 2 O decomposition in the oxidation reactorFigure based on [87, infoMil, 2001]Achieved environmental benefitsDepending on the catalyst filling height and the assessed time period, N 2 O average emissionslevels of 130 – 325 ppm are achieved, see Table 3.12.Cross-media effectsNone believed likely.Large Volume Inorganic Chemicals – Ammonia, Acids and Fertilisers 123