A rate based reactor model for BiodeNOx absorber units

The reactive absorption of NO in aqueous solutions of Fe-II(EDTA), resulting in the formation of a nitrosyl complex, Fe-II(EDTA)(NO), is a key step of the BiodeNOx process for the removal of NOx from industrial flue gas. Oxygen present in the flue gas will also absorb and oxidize Fe-II(EDTA). This is an undesired reaction, because the resulting Fe-III(EDTA) does not react with NO. To explore the industrial applicability of the process, a rate based model for the simultaneous reactive absorption of NO and O-2 in aqueous Fe-II(EDTA) solutions in a counter current packed column has been developed. The effect of process conditions on absorber performance (NO removal efficiency, selectivity, Fe-II(EDTA) conversion) have been assessed. Using standard conditions, the column height needed to remove 90% of an initial 250 ppm of NO was less than 1 m. The amount of oxidized iron was approximately equal to the amount of the nitrosyl complex, even though oxygen was present in a 200-fold excess over NO. The absorber performance was particularly dependent on the operating temperature, where lower temperatures favoured both the NO removal efficiency and selectivity. Remarkably, the model indicated that overdesign of the absorber can result in decreasing absorber performance. (C) 2007 Elsevier B.V. All rights reserved.

[1]  Hero J. Heeres,et al.  Experimental and modelling studies on the simultaneous absorption of NO and O-2 in aqueous iron chelate solutions , 2006 .

[2]  D. Wise,et al.  Diffusion coefficients of neon, krypton, xenon, carbon monoxide and nitric oxide in water at 10–60°C , 1968 .

[3]  R. Eldik,et al.  Tuning the Reversible Binding of NO to Iron(II) Aminocarboxylate and Related Complexes in Aqueous Solution , 2001 .

[4]  Antonie A. C. M. Beenackers,et al.  Kinetics of the oxidation of ferrous chelates of EDTA and HEDTA in aqueous solution , 1993 .

[5]  K. Westerterp,et al.  Chemical reactor design and operation , 1983 .

[6]  Hiroshi Takeuchi,et al.  GAS ABSORPTION WITH CHEMICAL REACTION IN PACKED COLUMNS , 1968 .

[7]  Jos Winkelman,et al.  Kinetics of the reaction of FeII(EDTA) with oxygen in aqueous solutions , 2005 .

[8]  M. Warmoeskerken,et al.  Transport Phenomena Data Companion , 2009 .

[9]  R. Reid,et al.  The Properties of Gases and Liquids , 1977 .

[10]  T. E. Daubert,et al.  Data compilation tables of properties of pure compounds , 1985 .

[11]  R. Eldik,et al.  Kinetics and mechanism of the autoxidation of iron(II) induced through chelation by ethylenediaminetetraacetate and related ligands , 1990 .

[12]  Hero J. Heeres,et al.  Experimental and Modeling Studies on the Absorption of NO in Aqueous Ferrous EDTA Solutions , 2005 .

[13]  E. R. Brown,et al.  Mechanism of oxidation of ferrous polydentate complexes by dioxygen , 1987 .

[14]  Hiroshi Takeuchi,et al.  MASS TRANSFER COEFFICIENTS BETWEEN GAS AND LIQUID PHASES IN PACKED COLUMNS , 1968 .

[15]  Daniel I. C. Wang,et al.  Simultaneous measurement of oxygen diffusion coefficients and solubilities in electrolyte solutions with a polarographic oxygen electrode , 1988 .

[16]  Hiroshi Machida,et al.  Oxidation kinetics of FeII-EDTA and FeII-NTA chelates by dissolved oxygen , 1987 .

[17]  S. R. Olsen,et al.  Diffusion of Iron and Iron Chelates in Soil 1 , 1971 .

[18]  J. Buchanan.  Holdup in Irrigated Ring-Packed Towers below the Loading Point , 1967 .