Effect of SO2 on the reaction of calcium hydroxide with CO2 at low temperatures / Liu, Chiung-Fang in Industrial & engineering chemistry research, Vol. 49 N° 19 (Octobre 2010)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 49 N° 19 (Octobre 2010) . - pp. 9052–9057 Titre : Effect of SO2 on the reaction of calcium hydroxide with CO2 at low temperatures Type de document : texte imprimé Auteurs : Liu, Chiung-Fang, Auteur ; Shin-Min Shih, Auteur ; Tsai-Bang Huang, Auteur Année de publication : 2010 Article en page(s) : pp. 9052–9057 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Hydroxide Low temperature CO2 Résumé : The flue gas generated from a coal-fired power plant contains CO2 and SO2. The effect of SO2 concentration (≤1000 ppm) on the reaction of CO2 with Ca(OH)2 was studied using a differential fixed-bed reactor under the low-temperature and humid conditions similar to those in the bag filters of a dry or semidry flue gas desulfurization (FGD) system. When both CO2 and SO2 were present, they reacted with Ca(OH)2 simultaneously to form calcium carbonate and sulfite, but part of the carbonate formed reacted further with SO2 to form sulfite. Ca(OH)2 ceased to react due to the formation of an impervious product layer. The fraction of carbonate increased significantly with decreasing SO2 concentration in the range below 500 ppm SO2, but the fraction of sulfite decreased little except in the range below 100 ppm SO2 or at a relative humidity (RH) above 70%. Both fractions of carbonate and sulfite increased markedly with increasing relative humidity and slightly with increasing temperature, but they were little affected by the CO2 concentration and the presence of O2. At SO2 concentrations ≤100 ppm, conversions of Ca(OH)2 to carbonate in the range comparable to or higher than the typical conversions of Ca(OH)2 for SO2 removal in a dry or semidry FGD process could be achieved. The results of this work are useful for evaluating the feasibility of using solid wastes containing CaO and/or Ca(OH)2 to capture CO2 from flue gas at low temperatures. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100924z [article] Effect of SO2 on the reaction of calcium hydroxide with CO2 at low temperatures [texte imprimé] / Liu, Chiung-Fang, Auteur ; Shin-Min Shih, Auteur ; Tsai-Bang Huang, Auteur . - 2010 . - pp. 9052–9057. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 19 (Octobre 2010) . - pp. 9052–9057 Mots-clés : Hydroxide Low temperature CO2 Résumé : The flue gas generated from a coal-fired power plant contains CO2 and SO2. The effect of SO2 concentration (≤1000 ppm) on the reaction of CO2 with Ca(OH)2 was studied using a differential fixed-bed reactor under the low-temperature and humid conditions similar to those in the bag filters of a dry or semidry flue gas desulfurization (FGD) system. When both CO2 and SO2 were present, they reacted with Ca(OH)2 simultaneously to form calcium carbonate and sulfite, but part of the carbonate formed reacted further with SO2 to form sulfite. Ca(OH)2 ceased to react due to the formation of an impervious product layer. The fraction of carbonate increased significantly with decreasing SO2 concentration in the range below 500 ppm SO2, but the fraction of sulfite decreased little except in the range below 100 ppm SO2 or at a relative humidity (RH) above 70%. Both fractions of carbonate and sulfite increased markedly with increasing relative humidity and slightly with increasing temperature, but they were little affected by the CO2 concentration and the presence of O2. At SO2 concentrations ≤100 ppm, conversions of Ca(OH)2 to carbonate in the range comparable to or higher than the typical conversions of Ca(OH)2 for SO2 removal in a dry or semidry FGD process could be achieved. The results of this work are useful for evaluating the feasibility of using solid wastes containing CaO and/or Ca(OH)2 to capture CO2 from flue gas at low temperatures. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100924z

Exemplaires

Code-barres	Cote	Support	Localisation	Section	Disponibilité
aucun exemplaire

Kinetics of the reaction of dense CaO particles with SO2 / Shin-Min Shih in Industrial & engineering chemistry research, Vol. 50 N° 22 (Novembre 2011)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 50 N° 22 (Novembre 2011) . - pp. 12409–12420 Titre : Kinetics of the reaction of dense CaO particles with SO2 Type de document : texte imprimé Auteurs : Shin-Min Shih, Auteur ; Jong-Cherng Lai, Auteur ; Chih-Hsiang Yang, Auteur Année de publication : 2012 Article en page(s) : pp. 12409–12420 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Kinetics Dioxide Thermogravimetric Résumé : The kinetics of the reaction of dense CaO particles (2.5 mm dia.) with sulfur dioxide was studied using a thermogravimetric technique under the conditions of 750–950 °C, 1000–5000 ppm SO2, and 6 h reaction time. The growth of CaSO4 product layer was observed using a scanning electron microscope. The effect of internal structural change due to reaction, which complicates the kinetic analysis of porous particles, was eliminated in the present case. The thickening of the product layer behaved as the shrinking-core type reaction. The product layer was composed of many CaSO4 grains, the size of which increased singnificantly with increasing temperature. The long-term reaction kinetics was well described by the shrinking-core model for changing particle size by considering the product layer diffusion and intrinsic chemical reaction. The apparent reaction order of SO2 was 0.3 and close to 1.0 only at low CaO conversions. The values of chemical reaction rate constant and the activation energy for chemical reaction rate constant or product layer diffusivity were in the range reported by previous investigators, but the values of the product layer diffusivity were much higher. The model equations for the case involving the inward or outward solid-state diffusion of ions were derived. The reaction kinetics can be explained by considering both the diffusion of Ca2+ and O2– ions and the diffusion of gaseous reactants. The product layer tended to fracture continually and form more cracks at higher temperatures, thus resulting in higher values of product layer diffusivity and a high activation energy for diffusivity, and leading to an apparent SO2 reaction order smaller than first order. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie2009668 [article] Kinetics of the reaction of dense CaO particles with SO2 [texte imprimé] / Shin-Min Shih, Auteur ; Jong-Cherng Lai, Auteur ; Chih-Hsiang Yang, Auteur . - 2012 . - pp. 12409–12420. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 22 (Novembre 2011) . - pp. 12409–12420 Mots-clés : Kinetics Dioxide Thermogravimetric Résumé : The kinetics of the reaction of dense CaO particles (2.5 mm dia.) with sulfur dioxide was studied using a thermogravimetric technique under the conditions of 750–950 °C, 1000–5000 ppm SO2, and 6 h reaction time. The growth of CaSO4 product layer was observed using a scanning electron microscope. The effect of internal structural change due to reaction, which complicates the kinetic analysis of porous particles, was eliminated in the present case. The thickening of the product layer behaved as the shrinking-core type reaction. The product layer was composed of many CaSO4 grains, the size of which increased singnificantly with increasing temperature. The long-term reaction kinetics was well described by the shrinking-core model for changing particle size by considering the product layer diffusion and intrinsic chemical reaction. The apparent reaction order of SO2 was 0.3 and close to 1.0 only at low CaO conversions. The values of chemical reaction rate constant and the activation energy for chemical reaction rate constant or product layer diffusivity were in the range reported by previous investigators, but the values of the product layer diffusivity were much higher. The model equations for the case involving the inward or outward solid-state diffusion of ions were derived. The reaction kinetics can be explained by considering both the diffusion of Ca2+ and O2– ions and the diffusion of gaseous reactants. The product layer tended to fracture continually and form more cracks at higher temperatures, thus resulting in higher values of product layer diffusivity and a high activation energy for diffusivity, and leading to an apparent SO2 reaction order smaller than first order. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie2009668

Exemplaires

Code-barres	Cote	Support	Localisation	Section	Disponibilité
aucun exemplaire

Kinetics of the reaction of hydrated lime with SO2 at low temperatures / Liu, Chiung-Fang ; Shin-Min Shih in Industrial & engineering chemistry research, Vol. 47 n°24 (Décembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 n°24 (Décembre 2008) . - p. 9878–9881 Titre : Kinetics of the reaction of hydrated lime with SO2 at low temperatures : effects of the presence of CO2, O2, and NOx Type de document : texte imprimé Auteurs : Liu, Chiung-Fang, Auteur ; Shin-Min Shih, Auteur Année de publication : 2009 Article en page(s) : p. 9878–9881 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : sulfation--hydrated lime Résumé : The effects of the presence of CO2, O2, and NOx in the flue gas on the kinetics of the sulfation of hydrated lime at low temperatures were studied using a differential fixed-bed reactor. When O2 and NOx were not present together the reaction kinetics was about the same as that under gas mixtures containing SO2, H2O, and N2 only. When both O2 and NOx were present, sulfation of hydrated lime was greatly enhanced, forming a large amount of calcium sulfate in addition to calcium sulfite. Sulfation of hydrated lime was well described by the surface coverage model, despite the gas-phase conditions being different. Relative humidity is the major factor affecting the reaction, and its effect was more marked when both O2 and NOx were present. The kinetic model equations obtained in this work can be used to describe the sulfation of hydrated lime in the low-temperature dry and semidry flue gas desulfurization processes with or without an upstream NOx removal unit. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801105s [article] Kinetics of the reaction of hydrated lime with SO2 at low temperatures : effects of the presence of CO2, O2, and NOx [texte imprimé] / Liu, Chiung-Fang, Auteur ; Shin-Min Shih, Auteur . - 2009 . - p. 9878–9881. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 n°24 (Décembre 2008) . - p. 9878–9881 Mots-clés : sulfation--hydrated lime Résumé : The effects of the presence of CO2, O2, and NOx in the flue gas on the kinetics of the sulfation of hydrated lime at low temperatures were studied using a differential fixed-bed reactor. When O2 and NOx were not present together the reaction kinetics was about the same as that under gas mixtures containing SO2, H2O, and N2 only. When both O2 and NOx were present, sulfation of hydrated lime was greatly enhanced, forming a large amount of calcium sulfate in addition to calcium sulfite. Sulfation of hydrated lime was well described by the surface coverage model, despite the gas-phase conditions being different. Relative humidity is the major factor affecting the reaction, and its effect was more marked when both O2 and NOx were present. The kinetic model equations obtained in this work can be used to describe the sulfation of hydrated lime in the low-temperature dry and semidry flue gas desulfurization processes with or without an upstream NOx removal unit. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801105s

Exemplaires

Code-barres	Cote	Support	Localisation	Section	Disponibilité
aucun exemplaire

Kinetics of the reaction of iron blast furnace slag/hydrated lime sorbents with SO2 at low temperatures / Liu, Chiung-Fang in Industrial & engineering chemistry research, Vol. 48 N° 18 (Septembre 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8335–8340 Titre : Kinetics of the reaction of iron blast furnace slag/hydrated lime sorbents with SO2 at low temperatures : effects of the presence of CO2, O2, and NOx Type de document : texte imprimé Auteurs : Liu, Chiung-Fang, Auteur ; Shin-Min Shih, Auteur Année de publication : 2010 Article en page(s) : pp. 8335–8340 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : CO2 O2 NOx Flue gas Differential fixed-bed reactor Résumé : The effects of the presence of CO2, O2, and NOx in the flue gas on the kinetics of the sulfation of blast furnace slag/hydrated lime sorbents at low temperatures were studied using a differential fixed-bed reactor. When O2 and NOx were not present simultaneously, the reaction kinetics was about the same as that under the gas mixtures containing SO2, H2O, and N2 only, being affected mainly by the relative humidity. The sulfation of sorbents can be described by the surface coverage model and the model equations derived for the latter case. When both O2 and NOx were present, the sulfation of sorbents was greatly enhanced, forming a great amount of sulfate in addition to sulfite. The surface coverage model is still valid in this case, but the model equations obtained show a more marked effect of relative humidity and negligible effects of SO2 concentration and temperature on the reaction. The effect of sorbent composition on the reaction kinetics was entirely represented by the effects of the initial specific surface area (Sg0) and the Ca molar content (M−1) of sorbent. The initial conversion rate of sorbent increased linearly with increasing Sg0, and the ultimate conversion increased linearly with increasing Sg0M−1. The model equations obtained in this work are applicable to describe the kinetics of the sulfation of the sorbents in the low-temperature dry and semidry flue gas desulfurization processes either with an upstream NOx removal unit or without. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900379c [article] Kinetics of the reaction of iron blast furnace slag/hydrated lime sorbents with SO2 at low temperatures : effects of the presence of CO2, O2, and NOx [texte imprimé] / Liu, Chiung-Fang, Auteur ; Shin-Min Shih, Auteur . - 2010 . - pp. 8335–8340. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8335–8340 Mots-clés : CO2 O2 NOx Flue gas Differential fixed-bed reactor Résumé : The effects of the presence of CO2, O2, and NOx in the flue gas on the kinetics of the sulfation of blast furnace slag/hydrated lime sorbents at low temperatures were studied using a differential fixed-bed reactor. When O2 and NOx were not present simultaneously, the reaction kinetics was about the same as that under the gas mixtures containing SO2, H2O, and N2 only, being affected mainly by the relative humidity. The sulfation of sorbents can be described by the surface coverage model and the model equations derived for the latter case. When both O2 and NOx were present, the sulfation of sorbents was greatly enhanced, forming a great amount of sulfate in addition to sulfite. The surface coverage model is still valid in this case, but the model equations obtained show a more marked effect of relative humidity and negligible effects of SO2 concentration and temperature on the reaction. The effect of sorbent composition on the reaction kinetics was entirely represented by the effects of the initial specific surface area (Sg0) and the Ca molar content (M−1) of sorbent. The initial conversion rate of sorbent increased linearly with increasing Sg0, and the ultimate conversion increased linearly with increasing Sg0M−1. The model equations obtained in this work are applicable to describe the kinetics of the sulfation of the sorbents in the low-temperature dry and semidry flue gas desulfurization processes either with an upstream NOx removal unit or without. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900379c

Exemplaires

Code-barres	Cote	Support	Localisation	Section	Disponibilité
aucun exemplaire

Reactivities of NaOH enhanced iron blast furnace slag/hydrated lime sorbents toward SO2 at low temperatures / Liu, Chiung-Fang in Industrial & engineering chemistry research, Vol. 49 N° 2 (Janvier 2010)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 49 N° 2 (Janvier 2010) . - pp 515–519 Titre : Reactivities of NaOH enhanced iron blast furnace slag/hydrated lime sorbents toward SO2 at low temperatures : effects of the Presence of CO2, O2, and NOx Type de document : texte imprimé Auteurs : Liu, Chiung-Fang, Auteur ; Shin-Min Shih, Auteur ; Yang, Jung-Hsin, Auteur Année de publication : 2010 Article en page(s) : pp 515–519 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Reactivities NaOH Hydrated lime sorbents. Résumé : The effects of the addition of NaOH on the reactivities toward SO2 of iron blast furnace slag/hydrated lime (BFS/HL) sorbents were studied without and with the presence of flue gas components, CO2, O2, and NOx, under the conditions prevailing in the bag filters of dry and semidry flue gas desulfurization processes. The reactivities of sorbents were markedly enhanced by the addition of NaOH when CO2, O2, and NOx were not present in the gas mixture. The enhancement effect mainly resulted from the deliquescent property of NaOH. With the presence of CO2, O2, and NOx at their typical concentrations in the flue gas, the sorbent reactivity was greatly increased due to the oxidation of bisulfite and sulfite ions to sulfate ions as well as the formation of deliquescent salts, calcium nitrite and nitrate, being enhanced by the presence of NO2 during the sulfation of a BFS/HL sorbent. The addition of NaOH in this case promoted the formation of sulfates but became less important in raising the sorbent reactivities for sorbents except BFS. Without the presence of CO2/O2/NOx, the BFS/HL sorbents with ratios ≤70/30 had higher reactivities than HL, but with the presence of CO2/O2/NOx, HL had the highest value of SO2 capture among the BFS/HL and BFS/HL/NaOH sorbents tested. Placing the SO2 removal unit before the NOx removal unit in practical operations can take advantage of the enhancement effect of CO2/O2/NOx on increasing the Ca utilization and SO2 capture of the sorbent. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9012425 [article] Reactivities of NaOH enhanced iron blast furnace slag/hydrated lime sorbents toward SO2 at low temperatures : effects of the Presence of CO2, O2, and NOx [texte imprimé] / Liu, Chiung-Fang, Auteur ; Shin-Min Shih, Auteur ; Yang, Jung-Hsin, Auteur . - 2010 . - pp 515–519. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 2 (Janvier 2010) . - pp 515–519 Mots-clés : Reactivities NaOH Hydrated lime sorbents. Résumé : The effects of the addition of NaOH on the reactivities toward SO2 of iron blast furnace slag/hydrated lime (BFS/HL) sorbents were studied without and with the presence of flue gas components, CO2, O2, and NOx, under the conditions prevailing in the bag filters of dry and semidry flue gas desulfurization processes. The reactivities of sorbents were markedly enhanced by the addition of NaOH when CO2, O2, and NOx were not present in the gas mixture. The enhancement effect mainly resulted from the deliquescent property of NaOH. With the presence of CO2, O2, and NOx at their typical concentrations in the flue gas, the sorbent reactivity was greatly increased due to the oxidation of bisulfite and sulfite ions to sulfate ions as well as the formation of deliquescent salts, calcium nitrite and nitrate, being enhanced by the presence of NO2 during the sulfation of a BFS/HL sorbent. The addition of NaOH in this case promoted the formation of sulfates but became less important in raising the sorbent reactivities for sorbents except BFS. Without the presence of CO2/O2/NOx, the BFS/HL sorbents with ratios ≤70/30 had higher reactivities than HL, but with the presence of CO2/O2/NOx, HL had the highest value of SO2 capture among the BFS/HL and BFS/HL/NaOH sorbents tested. Placing the SO2 removal unit before the NOx removal unit in practical operations can take advantage of the enhancement effect of CO2/O2/NOx on increasing the Ca utilization and SO2 capture of the sorbent. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9012425

Exemplaires

Code-barres	Cote	Support	Localisation	Section	Disponibilité
aucun exemplaire