The Experts below are selected from a list of 1860 Experts worldwide ranked by ideXlab platform
Nobuo Otsuka - One of the best experts on this subject based on the ideXlab platform.
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A Thermodynamic approach on vapor-condensation of corrosive salts from flue gas on boiler tubes in waste incinerators
Corrosion Science, 2008Co-Authors: Nobuo OtsukaAbstract:Abstract Thermodynamic Equilibrium Calculation was conducted to understand the effects of tube wall temperature, flue gas temperature, and waste chemistry on the type and amount of vapor-condensed “corrosive” salts from flue gas on superheater and waterwall tubes in waste incinerators. The amount of vapor-condensed compounds from flue gases at 650–950 °C on tube walls at 350–850 °C was calculated, upon combustion of 100 g waste with 1.6 stoichiometry (in terms of the air–fuel ratio). Flue gas temperature, rather than tube wall temperature, influenced the deposit chemistry of boiler tubes significantly. Chlorine, sulfur, sodium, potassium, and calcium contents in waste affected it as well.
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effects of fuel impurities on the fireside corrosion of boiler tubes in advanced power generating systems a Thermodynamic Calculation of deposit chemistry
Corrosion Science, 2002Co-Authors: Nobuo OtsukaAbstract:Abstract Thermodynamic Equilibrium Calculation relating fuel chemistry with flue-gas composition and volatile condensate deposits on tube metals upon combustion of various “dirty” fuel was conducted for a better understanding of the deposit chemistry of superheater tubes in steam-generating boilers. Corrosive impurities such as sodium, potassium, chlorine, and sulfur, inevitably involved in fuel, were considered in the Calculation. Possible influence of flue-gas temperature on deposit chemistry was investigated as well. Based on the flue-gas composition and the deposit chemistry, corrosion environments of steam-generating boilers firing various “dirty” fuel were discussed.
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Effects of fuel impurities on the fireside corrosion of boiler tubes in advanced power generating systems—a Thermodynamic Calculation of deposit chemistry
Corrosion Science, 2002Co-Authors: Nobuo OtsukaAbstract:Abstract Thermodynamic Equilibrium Calculation relating fuel chemistry with flue-gas composition and volatile condensate deposits on tube metals upon combustion of various “dirty” fuel was conducted for a better understanding of the deposit chemistry of superheater tubes in steam-generating boilers. Corrosive impurities such as sodium, potassium, chlorine, and sulfur, inevitably involved in fuel, were considered in the Calculation. Possible influence of flue-gas temperature on deposit chemistry was investigated as well. Based on the flue-gas composition and the deposit chemistry, corrosion environments of steam-generating boilers firing various “dirty” fuel were discussed.
Yitian Fang - One of the best experts on this subject based on the ideXlab platform.
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Predicting the vanadium speciation during petroleum coke combustion by Thermodynamic Equilibrium Calculation
Journal of Thermal Analysis and Calorimetry, 2017Co-Authors: Jiantao Zhao, Linxian Zhang, Xin Dai, Yitian FangAbstract:Petroleum coke (petcoke), as a substitute for natural gas and fuel oil, has been burning in boilers for heat and power production. The high content of vanadium (V) in petcoke is responsible for ash-related problems including fouling, corrosion and deposition. Thus, the behavior of V during petcoke combustion has become a subject of concern both in science and engineering. In this paper, Thermodynamic Equilibrium Calculations were performed to investigate the V speciation with the presence of main associated mineral elements (Si, Ca, Al, Fe, Ni and Na) during petcoke combustion. The results demonstrate that V participates in the reactions with Ca, Fe and Na, yielding V-containing chemical compounds (CaO)V2O5(s), (CaO)2V2O5(s), Fe(VO3)2(s) and (Na2O)V2O5(s), respectively. The formation of liquid species NaVO3 also takes place. Moreover, no interactions of V with Si, Al and Ni occur because no other V-containing species is formed over the whole range of temperatures. However, the associated mineral elements may co-influence the V species Equilibrium compositions dramatically. The formation of CaSiO3(s) and CaAl12O19(s) occurred at 1600 °C restrains the (CaO)2V2O5(s) production. Ca reacts with Si and Al to form CaAl2Si2O8(s), impeding the formation of (CaO)2V2O5(s). Na can also combine with Si and Al to generate NaAlSi3O8(s), inhibiting the (Na2O)V2O5(s) and NaVO3(l) production. It should be noted that VO2(g) exhibits high volatility (more than 90% (mol mol−1)) at high temperatures (1600 °C), whereas the presence of Ca results in a reduction in volatility of VO2(g) due to the formation of (CaO)2V2O5(s).
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predicting the vanadium speciation during petroleum coke gasification by Thermodynamic Equilibrium Calculation
Fuel, 2016Co-Authors: Jiantao Zhao, Shuai Guo, Xing Zhou, Yubo Liu, Jin Bai, Yitian FangAbstract:Abstract High temperature gasification has been considered as one of the most promising routes for the clean and efficient utilization of high-sulfur petroleum coke (petcoke). However, petcoke usually contains high content of vanadium (V). It has been proven that V element in petcoke can lead to fouling or corrosion problems in the process of combustion, which captures the attention to the fate of V during petcoke gasification. In this paper, Thermodynamic Equilibrium Calculations based on the FactSage were used to investigate the reaction mechanism of V with the main associated mineral elements (Si, Ca, Al, Fe, Ni and Na) during petcoke gasification. The influence of gasification temperature and atmospheres on the V species Equilibrium composition was also evaluated. The results indicate that V reacts with the mineral elements of Ca, Fe and Na to form V-containing species (CaO)3V2O5(s), FeV2O4(s), (Na2O)3V2O5(s) and (Na2O)2V2O5(l), respectively. The presence of H2S(g) suppresses the reactions of V with Ca and Fe due to the formation of sulfides (CaS and FeS). In addition, it is verified that V does not participate in the reactions with Si, Al and Ni. However, the associated mineral elements may have remarkable co-effects on V species Equilibrium composition. Ca reacts with Si or Al easily to form the Ca-containing minerals (CaSiO3(s), Ca3Si2O7(s), Ca2SiO4(s), CaAl4O7(s), CaAl2O4(s)), impeding the formation of (CaO)3V2O5(s). Na combines with Al to generate Na-containing minerals (NaAlO2(s), Na2Al12O19(s)), inhibiting the formation of (Na2O)3V2O5(s) and (Na2O)2V2O5(l). When all of the main associated mineral elements are present, the V-containing species formed in the whole process of gasification are V2O3(s), FeV2O4(s) and a small amount of VO2(g).
Masahiro Osako - One of the best experts on this subject based on the ideXlab platform.
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understanding the behavior of radioactive cesium during the incineration of contaminated municipal solid waste and sewage sludge by Thermodynamic Equilibrium Calculation
ACS omega, 2018Co-Authors: Kazuko Yui, Hidetoshi Kuramochi, Masahiro OsakoAbstract:Following the nuclear accident at the Fukushima Daiichi Nuclear Power Plant in 2011, even the municipal solid waste (MSW) and sewage sludge (SS) in northeastern Japan became contaminated by radioactive nuclides such as 137Cs and 134Cs. To understand the state of radioactive cesium (r-Cs) in the incineration residues of the municipal wastes, research groups studied the concentration and the chemical form of r-Cs in the residues, as well as its water-leaching behavior. In the present study, we conducted Thermodynamic Equilibrium Calculations to estimate the possible chemical forms of r-Cs in the incineration residues. Thermodynamic data for cesium oxides and aluminosilicates were collected and compiled into a new database to perform Equilibrium Calculations for systems that include Cs. The Calculation results suggested that Cs (radiocesium and stable cesium) in municipal solid waste was transformed into gaseous CsCl or crystalline aluminosilicate at incineration temperatures and, when a molten aluminosilica...
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understanding the behavior of radioactive cesium during the incineration of contaminated municipal solid waste and sewage sludge by Thermodynamic Equilibrium Calculation
ACS omega, 2018Co-Authors: Kazuko Yui, Hidetoshi Kuramochi, Masahiro OsakoAbstract:Following the nuclear accident at the Fukushima Daiichi Nuclear Power Plant in 2011, even the municipal solid waste (MSW) and sewage sludge (SS) in northeastern Japan became contaminated by radioac...
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Understanding the Behavior of Radioactive Cesium during the Incineration of Contaminated Municipal Solid Waste and Sewage Sludge by Thermodynamic Equilibrium Calculation
2018Co-Authors: Kazuko Yui, Hidetoshi Kuramochi, Masahiro OsakoAbstract:Following the nuclear accident at the Fukushima Daiichi Nuclear Power Plant in 2011, even the municipal solid waste (MSW) and sewage sludge (SS) in northeastern Japan became contaminated by radioactive nuclides such as 137Cs and 134Cs. To understand the state of radioactive cesium (r-Cs) in the incineration residues of the municipal wastes, research groups studied the concentration and the chemical form of r-Cs in the residues, as well as its water-leaching behavior. In the present study, we conducted Thermodynamic Equilibrium Calculations to estimate the possible chemical forms of r-Cs in the incineration residues. Thermodynamic data for cesium oxides and aluminosilicates were collected and compiled into a new database to perform Equilibrium Calculations for systems that include Cs. The Calculation results suggested that Cs (radiocesium and stable cesium) in municipal solid waste was transformed into gaseous CsCl or crystalline aluminosilicate at incineration temperatures and, when a molten aluminosilicate phase (i.e., slag phase) was generated, a proportion of the Cs species was dissolved into the slag phase. In the case of sewage sludge, Cs was calculated to be transformed mostly into crystalline aluminosilicate at incineration temperatures, whereas by analogy with the behaviors of Na and K, Ca,Cs-phosphate double salts were also potential incineration products. These results could account for the high leaching rates of r-Cs from the MSW incineration fly ash and the low leaching rates from the MSW incineration bottom ash and SS incineration fly ash reported in earlier studies. In the case of dewatered SS that included a large amount of slaked lime as a flocculant, it was exceptionally difficult for the Calculation to represent the fate of Cs, and we needed to include the contribution of silica sand in a fluidized-bed combustor in the Equilibrium Calculation to represent the low leaching rates of alkali species from the dewatered SS fly ash. From the results of the Thermodynamic Equilibrium Calculations and also from the calculated standard Gibbs energy of cesium aluminosilicate formation/decomposition reactions, the effects of waste composition and incineration temperature on the fate of Cs were examined: High incineration temperature and large amounts of Ca and Cl in the waste composition increased the fraction of gaseous CsCl in the furnace and thus resulted in the high distribution ratios of Cs in the fly ash of MSW and the high leaching rates of Cs from the fly ash
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Thermodynamic behavior of rare metals in the melting process of municipal solid waste msw incineration residues
Chemosphere, 2007Co-Authors: Changhwan Jung, Masahiro OsakoAbstract:This study aims to identify the Thermodynamic behavior of rare metal elements during the melting process of municipal solid waste incineration residues. The fate of several selected rare metal elements was investigated using two approaches: experimental and Thermodynamic Equilibrium Calculation at two actual melting plants. The results revealed that Ag, Bi, Ga, Ge, In, Pd, Sb, Te, and Tl are readily volatilized as chloride and/or gaseous forms and then condensed in melting furnace fly ash. On the other hand, Cr, Ni, Ta, V, and Zr tend to mostly remain in molten slag. Sn is volatilized as SnS (g) under reducing conditions while volatilization is suppressed under oxidizing conditions. Thermodynamically, total volatilization of Mn as MnCl2 (g) occurred with highly available chlorine under oxidizing conditions. However, at the actual plants, only a small proportion was volatilized. As for Co, Mo, and W, no volatilization occurred at the actual plants although the Calculations suggest that these elements can form volatile metal chloride and volatilize. Non-Equilibrium and heterogeneity of the actual plant melting furnace could explain the discrepancy. This study provided a good qualitative view of the behavior of rare metals in the melting process, but further investigation is required to produce a more accurate simulation and to resolve the discrepancy.
Anton Friedl - One of the best experts on this subject based on the ideXlab platform.
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scaling prediction based on Thermodynamic Equilibrium Calculation scopes and limitations
Desalination, 2009Co-Authors: Paul Schausberger, Ghulam M. Mustafa, Greg Leslie, Anton FriedlAbstract:Abstract A comprising Thermodynamic approach is presented to investigate the behavior of saline solutions with respect to CaCO 3 , CaSO 4 and SiO 2 scaling in water treatment processes. Thr Pitzer activity coefficient model is used to describe the aqueous species activities and the corresponding Equilibrium reactions are solved to determine the saline solution composition. A well evaluated parameter set for the system H-Na-Ca-Mg-OH-Cl-CO 3 -HCO 3 -CO 2 -SO 4 -HSO 4 -SiO 2 at 25°C is compiled and applied for Calculation of the pure scale solubilities as well as mixture effects such as CaCO 3 /CaSO 4 coprecipitation and silica adsorption. New data on silica removal dependant on the saline solution composition are used to estimate the ratio of silicate formation and silica adsorption onto other precipitating salts. Whereas the saturation states for pure scales are found to be well predictable at varying conditions, only qualtitative estimations for mixed scale formation can be achieved. Here, the predictability by Thermodynamic Equilibrium Calculation is shown to meet its present boundary and its valuable service for understanding the mechanisms of scaling and the species involved is highlighted.
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Scaling prediction based on Thermodynamic Equilibrium Calculation — scopes and limitations
Desalination, 2009Co-Authors: Paul Schausberger, Ghulam M. Mustafa, Greg Leslie, Anton FriedlAbstract:Abstract A comprising Thermodynamic approach is presented to investigate the behavior of saline solutions with respect to CaCO 3 , CaSO 4 and SiO 2 scaling in water treatment processes. Thr Pitzer activity coefficient model is used to describe the aqueous species activities and the corresponding Equilibrium reactions are solved to determine the saline solution composition. A well evaluated parameter set for the system H-Na-Ca-Mg-OH-Cl-CO 3 -HCO 3 -CO 2 -SO 4 -HSO 4 -SiO 2 at 25°C is compiled and applied for Calculation of the pure scale solubilities as well as mixture effects such as CaCO 3 /CaSO 4 coprecipitation and silica adsorption. New data on silica removal dependant on the saline solution composition are used to estimate the ratio of silicate formation and silica adsorption onto other precipitating salts. Whereas the saturation states for pure scales are found to be well predictable at varying conditions, only qualtitative estimations for mixed scale formation can be achieved. Here, the predictability by Thermodynamic Equilibrium Calculation is shown to meet its present boundary and its valuable service for understanding the mechanisms of scaling and the species involved is highlighted.
Jiantao Zhao - One of the best experts on this subject based on the ideXlab platform.
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Predicting the vanadium speciation during petroleum coke combustion by Thermodynamic Equilibrium Calculation
Journal of Thermal Analysis and Calorimetry, 2017Co-Authors: Jiantao Zhao, Linxian Zhang, Xin Dai, Yitian FangAbstract:Petroleum coke (petcoke), as a substitute for natural gas and fuel oil, has been burning in boilers for heat and power production. The high content of vanadium (V) in petcoke is responsible for ash-related problems including fouling, corrosion and deposition. Thus, the behavior of V during petcoke combustion has become a subject of concern both in science and engineering. In this paper, Thermodynamic Equilibrium Calculations were performed to investigate the V speciation with the presence of main associated mineral elements (Si, Ca, Al, Fe, Ni and Na) during petcoke combustion. The results demonstrate that V participates in the reactions with Ca, Fe and Na, yielding V-containing chemical compounds (CaO)V2O5(s), (CaO)2V2O5(s), Fe(VO3)2(s) and (Na2O)V2O5(s), respectively. The formation of liquid species NaVO3 also takes place. Moreover, no interactions of V with Si, Al and Ni occur because no other V-containing species is formed over the whole range of temperatures. However, the associated mineral elements may co-influence the V species Equilibrium compositions dramatically. The formation of CaSiO3(s) and CaAl12O19(s) occurred at 1600 °C restrains the (CaO)2V2O5(s) production. Ca reacts with Si and Al to form CaAl2Si2O8(s), impeding the formation of (CaO)2V2O5(s). Na can also combine with Si and Al to generate NaAlSi3O8(s), inhibiting the (Na2O)V2O5(s) and NaVO3(l) production. It should be noted that VO2(g) exhibits high volatility (more than 90% (mol mol−1)) at high temperatures (1600 °C), whereas the presence of Ca results in a reduction in volatility of VO2(g) due to the formation of (CaO)2V2O5(s).
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predicting the vanadium speciation during petroleum coke gasification by Thermodynamic Equilibrium Calculation
Fuel, 2016Co-Authors: Jiantao Zhao, Shuai Guo, Xing Zhou, Yubo Liu, Jin Bai, Yitian FangAbstract:Abstract High temperature gasification has been considered as one of the most promising routes for the clean and efficient utilization of high-sulfur petroleum coke (petcoke). However, petcoke usually contains high content of vanadium (V). It has been proven that V element in petcoke can lead to fouling or corrosion problems in the process of combustion, which captures the attention to the fate of V during petcoke gasification. In this paper, Thermodynamic Equilibrium Calculations based on the FactSage were used to investigate the reaction mechanism of V with the main associated mineral elements (Si, Ca, Al, Fe, Ni and Na) during petcoke gasification. The influence of gasification temperature and atmospheres on the V species Equilibrium composition was also evaluated. The results indicate that V reacts with the mineral elements of Ca, Fe and Na to form V-containing species (CaO)3V2O5(s), FeV2O4(s), (Na2O)3V2O5(s) and (Na2O)2V2O5(l), respectively. The presence of H2S(g) suppresses the reactions of V with Ca and Fe due to the formation of sulfides (CaS and FeS). In addition, it is verified that V does not participate in the reactions with Si, Al and Ni. However, the associated mineral elements may have remarkable co-effects on V species Equilibrium composition. Ca reacts with Si or Al easily to form the Ca-containing minerals (CaSiO3(s), Ca3Si2O7(s), Ca2SiO4(s), CaAl4O7(s), CaAl2O4(s)), impeding the formation of (CaO)3V2O5(s). Na combines with Al to generate Na-containing minerals (NaAlO2(s), Na2Al12O19(s)), inhibiting the formation of (Na2O)3V2O5(s) and (Na2O)2V2O5(l). When all of the main associated mineral elements are present, the V-containing species formed in the whole process of gasification are V2O3(s), FeV2O4(s) and a small amount of VO2(g).