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Investigation of parameters affecting gypsum dewatering properties in a wet flue gas desulphurization pilot plant / Brian B. Hansen in Industrial & engineering chemistry research, Vol. 51 N° 30 (Août 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 30 (Août 2012) . - pp. 10100–10107 Titre : Investigation of parameters affecting gypsum dewatering properties in a wet flue gas desulphurization pilot plant Type de document : texte imprimé Auteurs : Brian B. Hansen, Auteur ; Soren Kiil, Auteur Année de publication : 2012 Article en page(s) : pp. 10100–10107 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Gas  Desulphurization Résumé : Wet flue gas desulphurization (FGD) plants with forced oxidation, installed at coal and oil fired power plants for removal of SO2(g), must produce gypsum of high quality. However, quality issues such as an excessive moisture content, due to poor gypsum dewatering properties, may occur from time to time. In this work, the particle size distribution, morphology, and filtration rate of wet FGD gypsum formed in a pilot-scale experimental setup, operated in forced oxidation mode, have been studied. The influence of holding tank residence time (10–408 h), solids content (30–169 g/L), and the presence of impurities (0.002 M Al2F6; 50 g quartz/L; 0.02 M Al3+, and 0.040 M Mg2+) were investigated. In addition, slurry from a full-scale wet FGD plant, experiencing formation of flat shaped crystals and poor gypsum dewatering properties, was transferred to the pilot plant to test if the plant would now start to produce low quality gypsum. The crystals formed in the pilot plant, on the basis of the full-scale slurry did, however, show acceptable filtration rates and crystal morphologies closer to the prismatic crystals from after pilot plant experiments with demineralized water. The gypsum slurry filtration rates were generally high, but a shorter residence time (10 h) and gypsum crystals experiencing breakage and/or attrition (408 h) showed slightly lower filtration rates. Both these experiments contained a higher fraction of fines, which may explain the slightly lower filtration rates. Crystals formed at a higher solids concentration and longer residence time (169 g/L and 120 h) showed a higher proportion of flat crystals, and the XRD pattern contained strong peaks at 31.1° (as the full-scale gypsum) and 29.1°, but no change in the filtration rate was obtained. It has not been possible in the pilot plant to form flat gypsum flakes with poor dewatering properties similar to those observed in full-scale plants. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie3005435 [article] Investigation of parameters affecting gypsum dewatering properties in a wet flue gas desulphurization pilot plant [texte imprimé] / Brian B. Hansen, Auteur ; Soren Kiil, Auteur . - 2012 . - pp. 10100–10107. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 30 (Août 2012) . - pp. 10100–10107 Mots-clés : Gas  Desulphurization Résumé : Wet flue gas desulphurization (FGD) plants with forced oxidation, installed at coal and oil fired power plants for removal of SO2(g), must produce gypsum of high quality. However, quality issues such as an excessive moisture content, due to poor gypsum dewatering properties, may occur from time to time. In this work, the particle size distribution, morphology, and filtration rate of wet FGD gypsum formed in a pilot-scale experimental setup, operated in forced oxidation mode, have been studied. The influence of holding tank residence time (10–408 h), solids content (30–169 g/L), and the presence of impurities (0.002 M Al2F6; 50 g quartz/L; 0.02 M Al3+, and 0.040 M Mg2+) were investigated. In addition, slurry from a full-scale wet FGD plant, experiencing formation of flat shaped crystals and poor gypsum dewatering properties, was transferred to the pilot plant to test if the plant would now start to produce low quality gypsum. The crystals formed in the pilot plant, on the basis of the full-scale slurry did, however, show acceptable filtration rates and crystal morphologies closer to the prismatic crystals from after pilot plant experiments with demineralized water. The gypsum slurry filtration rates were generally high, but a shorter residence time (10 h) and gypsum crystals experiencing breakage and/or attrition (408 h) showed slightly lower filtration rates. Both these experiments contained a higher fraction of fines, which may explain the slightly lower filtration rates. Crystals formed at a higher solids concentration and longer residence time (169 g/L and 120 h) showed a higher proportion of flat crystals, and the XRD pattern contained strong peaks at 31.1° (as the full-scale gypsum) and 29.1°, but no change in the filtration rate was obtained. It has not been possible in the pilot plant to form flat gypsum flakes with poor dewatering properties similar to those observed in full-scale plants. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie3005435

Performan!ce of a wet flue gas desulfurization pilot plant under oxy-fuel conditions / Brian B. Hansen in Industrial & engineering chemistry research, Vol. 50 N° 8 (Avril 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 8 (Avril 2011) . - pp. 4238–4244 Titre : Performan!ce of a wet flue gas desulfurization pilot plant under oxy-fuel conditions Type de document : texte imprimé Auteurs : Brian B. Hansen, Auteur ; Folmer Fogh, Auteur ; Niels Ole Knudsen, Auteur Année de publication : 2011 Article en page(s) : pp. 4238–4244 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Gas  Desulfurization  Oxy  fuel Résumé : Oxy-fuel firing is a promising technology that should enable the capture and storage of anthropogenic CO2 emissions from large stationary sources such as power plants and heavy industry. However, this new technology has a high energy demand for air separation and CO2 compression and storage. Unresolved issues, such as determination of the optimal recycle location of flue gas, the flue gas cleaning steps required (SO2, NOx, and particles), and the impact of an oxy-fuel flue gas on the cleaning steps, also persist. The aim of this work was to study the performance of the wet flue gas desulfurization (FGD) process under operating conditions corresponding to oxy-fuel firing. The most important output parameters were the overall degree of desulfurization and the residual limestone concentration in the gypsum slurry. Pilot-scale experiments quantified that the introduction of a flue gas with 90 vol % CO2, at a holding tank pH 5.4, reduced the limestone dissolution rate significantly and thereby increased the residual, particulate limestone concentration in the gypsum slurry from 3.2 to 5.0 g/L slurry relative to a base-case (air-firing) experiment with a flue gas CO2 concentration around 7 vol %. In the same experiment, due to the higher residual limestone concentration, the degree of desulfurization increased from 91 to 94%. The addition of 10 mM adipic acid to the slurry was not sufficient to return the increased concentration of residual limestone to the base-case level, but an additional increase in desulfurization degree, from 94 to 97%, was obtained. Using a holding tank pH 5.0 (no adipic acid) returned both parameters to the levels observed in the base-case experiment. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie1022173 [article] Performan!ce of a wet flue gas desulfurization pilot plant under oxy-fuel conditions [texte imprimé] / Brian B. Hansen, Auteur ; Folmer Fogh, Auteur ; Niels Ole Knudsen, Auteur . - 2011 . - pp. 4238–4244. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 8 (Avril 2011) . - pp. 4238–4244 Mots-clés : Gas  Desulfurization  Oxy  fuel Résumé : Oxy-fuel firing is a promising technology that should enable the capture and storage of anthropogenic CO2 emissions from large stationary sources such as power plants and heavy industry. However, this new technology has a high energy demand for air separation and CO2 compression and storage. Unresolved issues, such as determination of the optimal recycle location of flue gas, the flue gas cleaning steps required (SO2, NOx, and particles), and the impact of an oxy-fuel flue gas on the cleaning steps, also persist. The aim of this work was to study the performance of the wet flue gas desulfurization (FGD) process under operating conditions corresponding to oxy-fuel firing. The most important output parameters were the overall degree of desulfurization and the residual limestone concentration in the gypsum slurry. Pilot-scale experiments quantified that the introduction of a flue gas with 90 vol % CO2, at a holding tank pH 5.4, reduced the limestone dissolution rate significantly and thereby increased the residual, particulate limestone concentration in the gypsum slurry from 3.2 to 5.0 g/L slurry relative to a base-case (air-firing) experiment with a flue gas CO2 concentration around 7 vol %. In the same experiment, due to the higher residual limestone concentration, the degree of desulfurization increased from 91 to 94%. The addition of 10 mM adipic acid to the slurry was not sufficient to return the increased concentration of residual limestone to the base-case level, but an additional increase in desulfurization degree, from 94 to 97%, was obtained. Using a holding tank pH 5.0 (no adipic acid) returned both parameters to the levels observed in the base-case experiment. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie1022173