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Comparing the performance of recirculating cyclones applied to the dry scrubbing of gaseous HCl with hydrated lime / Vania Chibante in Industrial & engineering chemistry research, Vol. 48 N°2 (Janvier 2009)

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N°2 (Janvier 2009) . - p. 1029–1035 Titre : Comparing the performance of recirculating cyclones applied to the dry scrubbing of gaseous HCl with hydrated lime Type de document : texte imprimé Auteurs : Vania Chibante, Auteur ; Ana M. Fonseca, Auteur ; Romualdo L. R. Salcedo, Auteur Année de publication : 2009 Article en page(s) : p. 1029–1035 Note générale : chimical engineering Langues : Anglais (eng) Mots-clés : Recirculating  cyclone  systems Résumé : Recirculating cyclone systems, combining a numerically optimized reverse flow gas cyclone (RS_VHE geometry) with a straight-through cyclone concentrator, were employed as reaction chambers for the dry scrubbing of gaseous hydrogen chloride with solid hydrated lime particles. The performance of this technology was tested at laboratory scale with two differently sized RS_VHE cyclones (0.020 and 0.026 m internal diameter) coupled to the same recirculator of 0.020 m internal diameter. The experimental conditions were the following: reaction temperature ≈ 326 K, gas flow rate ≈ 2.9 × 10−4 m3·s−1 at STP, and relative humidity of the gas ≈ 8.5%. The experimental variables were the solids feed rate [(1.0−9.2) × 10−7 kg·s−1] and HCl concentration in the inlet gas [(0.35−2.8) × 10−2 mol·m−3], giving different values for the ratio between the amount of fresh hydrated lime and HCl feed at the inlet of the recirculating cyclone systems (R) and that corresponding to the stoichiometric quantity (SR). The acid removal efficiencies ranged from 10 to 96%, and the best performances were obtained for high values of the ratio R/SR. Increasing the cyclone diameter while maintaining cyclone geometry improved the performance of the acid gas removal as well as the solid reactant conversion, but the average particle collection efficiency was lowered from (98.0 ± 0.7)% to (89.3 ± 1.7)%. [article] Comparing the performance of recirculating cyclones applied to the dry scrubbing of gaseous HCl with hydrated lime [texte imprimé] / Vania Chibante, Auteur ; Ana M. Fonseca, Auteur ; Romualdo L. R. Salcedo, Auteur . - 2009 . - p. 1029–1035. chimical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°2 (Janvier 2009) . - p. 1029–1035 Mots-clés : Recirculating  cyclone  systems Résumé : Recirculating cyclone systems, combining a numerically optimized reverse flow gas cyclone (RS_VHE geometry) with a straight-through cyclone concentrator, were employed as reaction chambers for the dry scrubbing of gaseous hydrogen chloride with solid hydrated lime particles. The performance of this technology was tested at laboratory scale with two differently sized RS_VHE cyclones (0.020 and 0.026 m internal diameter) coupled to the same recirculator of 0.020 m internal diameter. The experimental conditions were the following: reaction temperature ≈ 326 K, gas flow rate ≈ 2.9 × 10−4 m3·s−1 at STP, and relative humidity of the gas ≈ 8.5%. The experimental variables were the solids feed rate [(1.0−9.2) × 10−7 kg·s−1] and HCl concentration in the inlet gas [(0.35−2.8) × 10−2 mol·m−3], giving different values for the ratio between the amount of fresh hydrated lime and HCl feed at the inlet of the recirculating cyclone systems (R) and that corresponding to the stoichiometric quantity (SR). The acid removal efficiencies ranged from 10 to 96%, and the best performances were obtained for high values of the ratio R/SR. Increasing the cyclone diameter while maintaining cyclone geometry improved the performance of the acid gas removal as well as the solid reactant conversion, but the average particle collection efficiency was lowered from (98.0 ± 0.7)% to (89.3 ± 1.7)%.

Determination of the low - temperature water − gas shift reaction kinetics using a cu - based catalyst / Diogo Mendes in Industrial & engineering chemistry research, Vol. 49 N° 22 (Novembre 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 22 (Novembre 2010) . - pp. 11269–11279 Titre : Determination of the low - temperature water − gas shift reaction kinetics using a cu - based catalyst Type de document : texte imprimé Auteurs : Diogo Mendes, Auteur ; Vania Chibante, Auteur ; Adelio Mendes, Auteur Année de publication : 2011 Article en page(s) : pp. 11269–11279 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Gas  Kinetics Résumé : An integral packed-bed reactor was used to determine the kinetics of the water−gas shift (WGS) reaction over a CuO/ZnO/Al2O3 catalyst, under operating conditions such that there was no film or intraparticle resistance. Experiments were carried out over a wide range of temperatures and space times using a typical reformate gas mixture (4.70% CO, 34.78% H2O, 28.70% H2, 10.16% CO2, balance N2). In the first part of the work, three different mechanistic-rate equations and two empirical kinetic models are proposed to describe the WGS kinetic data throughout the entire range of temperatures. To improve the independence of the parameters in using the Arrhenius and van’t Hoff equations, the temperature was centered. Good agreement was obtained between the Langmuir−Hinshelwood (LH) rate equations and the experimental results. Further, analysis using two different temperature ranges for parameter estimation revealed distinct rate-controlling mechanisms for each range. For temperatures of 180−200 °C, the associative (LH) mechanism was predominant, whereas the redox pathway showed the best fit to the experimental reaction rates in the range of 230−300 °C. Finally, an isothermal plug-flow reactor model was used to simulate the packed-bed tubular reactor for the WGS reaction using the composed kinetics. The reactor model was assessed against the experimental CO outlet concentration, and satisfactory agreement was found between the model predictions and the experimental results. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie101137b [article] Determination of the low - temperature water − gas shift reaction kinetics using a cu - based catalyst [texte imprimé] / Diogo Mendes, Auteur ; Vania Chibante, Auteur ; Adelio Mendes, Auteur . - 2011 . - pp. 11269–11279. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 22 (Novembre 2010) . - pp. 11269–11279 Mots-clés : Gas  Kinetics Résumé : An integral packed-bed reactor was used to determine the kinetics of the water−gas shift (WGS) reaction over a CuO/ZnO/Al2O3 catalyst, under operating conditions such that there was no film or intraparticle resistance. Experiments were carried out over a wide range of temperatures and space times using a typical reformate gas mixture (4.70% CO, 34.78% H2O, 28.70% H2, 10.16% CO2, balance N2). In the first part of the work, three different mechanistic-rate equations and two empirical kinetic models are proposed to describe the WGS kinetic data throughout the entire range of temperatures. To improve the independence of the parameters in using the Arrhenius and van’t Hoff equations, the temperature was centered. Good agreement was obtained between the Langmuir−Hinshelwood (LH) rate equations and the experimental results. Further, analysis using two different temperature ranges for parameter estimation revealed distinct rate-controlling mechanisms for each range. For temperatures of 180−200 °C, the associative (LH) mechanism was predominant, whereas the redox pathway showed the best fit to the experimental reaction rates in the range of 230−300 °C. Finally, an isothermal plug-flow reactor model was used to simulate the packed-bed tubular reactor for the WGS reaction using the composed kinetics. The reactor model was assessed against the experimental CO outlet concentration, and satisfactory agreement was found between the model predictions and the experimental results. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie101137b