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

Chapter 3600N2O emissions in ppm500400300200Campaigns 2002 - 2003 and 2003 - 2004Figure 3.8: Achieved N 2 O emission levels at the example plant[17, 2nd TWG meeting, 2004]. The example plant operates a 5 bar oxidation with a gauzetemperature of 890 ºC. The reactor chamber is extended by 4 metres.Operational dataFor a modern dual pressure plant, a correlation between the chamber extension in metres and theN 2 O decomposition rate in % is given in [104, Schöffel, 2001], assuming a temperature gradientalong the decomposition chamber. For example, a decomposition rate of 80 % is predicted tobe achieved by an extension of about 7 metres.ApplicabilityApplicable to new plants. Not applicable to low pressure plants. Hydro Agri (Yara) installedthis system successfully without measurable effects on the NO yield in Porsgrunn (Norway).Retrofitting the technique in existing plants is not considered because of the "excessive" costs[104, Schöffel, 2001].The applicability is restricted actually to a maximum reactor diameter lower than 4 metres,because of the lack of mechanical support of the oxidation catalyst [154, TWG on LVIC-AAF,2006].Economics• low additional investment costs for new plants• much higher investment cost for existing plants• negligible additional operational costs.Driving force for implementationReduction of N 2 O emissions.References to literature and example plants[17, 2nd TWG meeting, 2004, 80, Jenssen, 2004, 87, infoMil, 2001, 104, Schöffel, 2001], Yara,Porsgrunn (1991).122 Large Volume Inorganic Chemicals – Ammonia, Acids and Fertilisers