The Experts below are selected from a list of 42 Experts worldwide ranked by ideXlab platform
Lingxue Kong - One of the best experts on this subject based on the ideXlab platform.
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crystallization kinetics and tcv prediction of Coal ash slag under slag tapping conditions in an entrained flow gasifier
Fuel, 2020Co-Authors: Lingxue Kong, Bernd Meyer, Jin Bai, Zongqing Bai, Xi Cao, Huiling Zhao, Stefan GuhlAbstract:Abstract Slag blockages in the bottom of gasifiers cause unplanned shutdowns and huge losses for syngas utilization downstream of gasification. The sudden viscosity increase by crystal precipitation leads to slag blockage during slag tapping in entrained flow gasifiers. The temperature at which the viscosity abruptly increases is the temperature of critical viscosity (TCV), which is the strict low limit temperature for slag tapping. A comprehensive investigation of slag crystallization kinetics was performed to illustrate TCV in this work. Five slag samples with three different dominant mineral phases that commonly appear in Coal ash slag were selected by thermodynamic calculations. The single hot thermocouple technique (SHTT) was applied to analyze the crystallization kinetics based on Avrami and JMA theory. The kinetic analysis indicated that anorthite showed heterogeneous nucleation and grew with a two-dimensional crystalline pattern. The temperature range for anorthite crystallization was approximately 150 °C. Corundum exhibited heterogeneous nucleation and one-dimensional growth pattern. The maximum crystal ratio was 52% for corundum at the temperature of 98 °C. Mullite showed a low E c value, resulting in a high Ton. Rapid crystallization of mullite was observed at 60 °C due to homogeneous nucleation and two-dimensional crystallization. In this work, TCV was revealed by crystallization kinetics for the first time. The relationship between TCV and the activation energy, maximum crystalline rate, and initial crystallization temperature was built to illustrate the influence of crystallization on TCV. Three equations were used for TCV prediction to guide Coal Selection and slag tapping in entrained flow gasifiers.
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effect of cao fe2o3 ratio on fusibility of Coal ashes with high silica and alumina levels and prediction
Fuel, 2020Co-Authors: Wenju Shi, Lingxue Kong, Jin Bai, Zongqing Bai, Stefan Guhl, Huiling Zhao, Bernd MeyerAbstract:Abstract Ash fusibility which is usually investigated and evaluated by the ash chemical compositions is widely used to guide the Coal Selection in boiler and gasifier. Calcium and iron are the main basic oxides in Coal ash, which tend to decrease ash fusion temperatures (AFTs). However, the change of AFTs varied with CaO/Fe2O3 mass ratio is not yet revealed. In this work, effect of CaO/Fe2O3 ratio on the fusibility of ash with high silica and alumina levels was explored under weak reducing atmosphere (CO: CO2 = 3/2, volume ratio). Thermodynamic calculations were applied to investigate the fusion behavior. A general rise of AFTs with the increasing CaO/Fe2O3 ratio was verified, especially for the Coal ash with low SiO2 + Al2O3 level and SiO2/Al2O3 mass ratio. Mullite and anorthite are main refractory minerals phase of the ash samples with high SiO2 and Al2O3 levels. The fusion of the ash in anorthite primary phase is the “soft-melting” mechanism, and liquidus temperature was well used to predict flow temperature (FT). However, the liquidus temperature should not be used to predict FT of the ash in mullite primary phase due to the “melting-dissolve” mechanism. A Tmullite model was proposed to predict FT for the ashes in mullite primary phase. The deviation of predicted and measured FT was within the measuring error range (±40 °C), which was supported by 25 real Coal ashes.
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the key for sodium rich Coal utilization in entrained flow gasifier the role of sodium on slag viscosity temperature behavior at high temperatures
Applied Energy, 2017Co-Authors: Xiaodong Chen, Lingxue Kong, Jin Bai, Xin Dai, Zongqing BaiAbstract:Abstract Tremendous sodium-rich Coal in China has unique ash compositions, and the entrained flow gasification is one of the best choices to use sodium-rich Coal for Coal chemical industry. The entrained flow gasifiers require smooth slag tapping for long term and safe running, but the viscosity-temperature behavior of high-sodium slags is unknown, which limits the utilization of sodium-rich Coal. In this study, viscosity-temperature behavior of high-sodium Coal ash slags was revealed for the first time, and the parameter of slag network structure and index of slag crystallization tendency is raised for slag viscosity evaluation. The results show that Na 2 O provides O 2− ions which break Si O Si bonds and slag network structure. However, Al 3+ ions are absorbed into silicate network, acting as a network former with the ionic charge-compensation effect of Na + . The classic structural parameter (fraction of non-bridging oxygen, NBO) is modified to evaluate the high-sodium slag viscosity accurately by taking Al 3+ into account. NBO fraction decreases as Na 2 O content increases, leading to the decrease of slag viscosity. Below T liq , slags are prone to be crystalline slag with increasing Na 2 O content or glassy slag with increase in SiO 2 /Al 2 O 3 ratio (S/A). A novel index, namely glassy slag formation ability (G), is established to quantitatively evaluate the crystallization tendency of Coal ash slags. G is the ratio of activation energy for viscous flow ( E η ) to T liq . The slag will exhibit the glassy behavior when G is higher than 0.16 kJ/(mol·K). The results enhance the knowledge of viscosity-temperature behavior of high-sodium Coal ash slags and will be helpful for Coal Selection and blending to avoid slag blockage in entrained flow gasification.
Zongqing Bai - One of the best experts on this subject based on the ideXlab platform.
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crystallization kinetics and tcv prediction of Coal ash slag under slag tapping conditions in an entrained flow gasifier
Fuel, 2020Co-Authors: Lingxue Kong, Bernd Meyer, Jin Bai, Zongqing Bai, Xi Cao, Huiling Zhao, Stefan GuhlAbstract:Abstract Slag blockages in the bottom of gasifiers cause unplanned shutdowns and huge losses for syngas utilization downstream of gasification. The sudden viscosity increase by crystal precipitation leads to slag blockage during slag tapping in entrained flow gasifiers. The temperature at which the viscosity abruptly increases is the temperature of critical viscosity (TCV), which is the strict low limit temperature for slag tapping. A comprehensive investigation of slag crystallization kinetics was performed to illustrate TCV in this work. Five slag samples with three different dominant mineral phases that commonly appear in Coal ash slag were selected by thermodynamic calculations. The single hot thermocouple technique (SHTT) was applied to analyze the crystallization kinetics based on Avrami and JMA theory. The kinetic analysis indicated that anorthite showed heterogeneous nucleation and grew with a two-dimensional crystalline pattern. The temperature range for anorthite crystallization was approximately 150 °C. Corundum exhibited heterogeneous nucleation and one-dimensional growth pattern. The maximum crystal ratio was 52% for corundum at the temperature of 98 °C. Mullite showed a low E c value, resulting in a high Ton. Rapid crystallization of mullite was observed at 60 °C due to homogeneous nucleation and two-dimensional crystallization. In this work, TCV was revealed by crystallization kinetics for the first time. The relationship between TCV and the activation energy, maximum crystalline rate, and initial crystallization temperature was built to illustrate the influence of crystallization on TCV. Three equations were used for TCV prediction to guide Coal Selection and slag tapping in entrained flow gasifiers.
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effect of cao fe2o3 ratio on fusibility of Coal ashes with high silica and alumina levels and prediction
Fuel, 2020Co-Authors: Wenju Shi, Lingxue Kong, Jin Bai, Zongqing Bai, Stefan Guhl, Huiling Zhao, Bernd MeyerAbstract:Abstract Ash fusibility which is usually investigated and evaluated by the ash chemical compositions is widely used to guide the Coal Selection in boiler and gasifier. Calcium and iron are the main basic oxides in Coal ash, which tend to decrease ash fusion temperatures (AFTs). However, the change of AFTs varied with CaO/Fe2O3 mass ratio is not yet revealed. In this work, effect of CaO/Fe2O3 ratio on the fusibility of ash with high silica and alumina levels was explored under weak reducing atmosphere (CO: CO2 = 3/2, volume ratio). Thermodynamic calculations were applied to investigate the fusion behavior. A general rise of AFTs with the increasing CaO/Fe2O3 ratio was verified, especially for the Coal ash with low SiO2 + Al2O3 level and SiO2/Al2O3 mass ratio. Mullite and anorthite are main refractory minerals phase of the ash samples with high SiO2 and Al2O3 levels. The fusion of the ash in anorthite primary phase is the “soft-melting” mechanism, and liquidus temperature was well used to predict flow temperature (FT). However, the liquidus temperature should not be used to predict FT of the ash in mullite primary phase due to the “melting-dissolve” mechanism. A Tmullite model was proposed to predict FT for the ashes in mullite primary phase. The deviation of predicted and measured FT was within the measuring error range (±40 °C), which was supported by 25 real Coal ashes.
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the key for sodium rich Coal utilization in entrained flow gasifier the role of sodium on slag viscosity temperature behavior at high temperatures
Applied Energy, 2017Co-Authors: Xiaodong Chen, Lingxue Kong, Jin Bai, Xin Dai, Zongqing BaiAbstract:Abstract Tremendous sodium-rich Coal in China has unique ash compositions, and the entrained flow gasification is one of the best choices to use sodium-rich Coal for Coal chemical industry. The entrained flow gasifiers require smooth slag tapping for long term and safe running, but the viscosity-temperature behavior of high-sodium slags is unknown, which limits the utilization of sodium-rich Coal. In this study, viscosity-temperature behavior of high-sodium Coal ash slags was revealed for the first time, and the parameter of slag network structure and index of slag crystallization tendency is raised for slag viscosity evaluation. The results show that Na 2 O provides O 2− ions which break Si O Si bonds and slag network structure. However, Al 3+ ions are absorbed into silicate network, acting as a network former with the ionic charge-compensation effect of Na + . The classic structural parameter (fraction of non-bridging oxygen, NBO) is modified to evaluate the high-sodium slag viscosity accurately by taking Al 3+ into account. NBO fraction decreases as Na 2 O content increases, leading to the decrease of slag viscosity. Below T liq , slags are prone to be crystalline slag with increasing Na 2 O content or glassy slag with increase in SiO 2 /Al 2 O 3 ratio (S/A). A novel index, namely glassy slag formation ability (G), is established to quantitatively evaluate the crystallization tendency of Coal ash slags. G is the ratio of activation energy for viscous flow ( E η ) to T liq . The slag will exhibit the glassy behavior when G is higher than 0.16 kJ/(mol·K). The results enhance the knowledge of viscosity-temperature behavior of high-sodium Coal ash slags and will be helpful for Coal Selection and blending to avoid slag blockage in entrained flow gasification.
Jin Bai - One of the best experts on this subject based on the ideXlab platform.
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crystallization kinetics and tcv prediction of Coal ash slag under slag tapping conditions in an entrained flow gasifier
Fuel, 2020Co-Authors: Lingxue Kong, Bernd Meyer, Jin Bai, Zongqing Bai, Xi Cao, Huiling Zhao, Stefan GuhlAbstract:Abstract Slag blockages in the bottom of gasifiers cause unplanned shutdowns and huge losses for syngas utilization downstream of gasification. The sudden viscosity increase by crystal precipitation leads to slag blockage during slag tapping in entrained flow gasifiers. The temperature at which the viscosity abruptly increases is the temperature of critical viscosity (TCV), which is the strict low limit temperature for slag tapping. A comprehensive investigation of slag crystallization kinetics was performed to illustrate TCV in this work. Five slag samples with three different dominant mineral phases that commonly appear in Coal ash slag were selected by thermodynamic calculations. The single hot thermocouple technique (SHTT) was applied to analyze the crystallization kinetics based on Avrami and JMA theory. The kinetic analysis indicated that anorthite showed heterogeneous nucleation and grew with a two-dimensional crystalline pattern. The temperature range for anorthite crystallization was approximately 150 °C. Corundum exhibited heterogeneous nucleation and one-dimensional growth pattern. The maximum crystal ratio was 52% for corundum at the temperature of 98 °C. Mullite showed a low E c value, resulting in a high Ton. Rapid crystallization of mullite was observed at 60 °C due to homogeneous nucleation and two-dimensional crystallization. In this work, TCV was revealed by crystallization kinetics for the first time. The relationship between TCV and the activation energy, maximum crystalline rate, and initial crystallization temperature was built to illustrate the influence of crystallization on TCV. Three equations were used for TCV prediction to guide Coal Selection and slag tapping in entrained flow gasifiers.
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effect of cao fe2o3 ratio on fusibility of Coal ashes with high silica and alumina levels and prediction
Fuel, 2020Co-Authors: Wenju Shi, Lingxue Kong, Jin Bai, Zongqing Bai, Stefan Guhl, Huiling Zhao, Bernd MeyerAbstract:Abstract Ash fusibility which is usually investigated and evaluated by the ash chemical compositions is widely used to guide the Coal Selection in boiler and gasifier. Calcium and iron are the main basic oxides in Coal ash, which tend to decrease ash fusion temperatures (AFTs). However, the change of AFTs varied with CaO/Fe2O3 mass ratio is not yet revealed. In this work, effect of CaO/Fe2O3 ratio on the fusibility of ash with high silica and alumina levels was explored under weak reducing atmosphere (CO: CO2 = 3/2, volume ratio). Thermodynamic calculations were applied to investigate the fusion behavior. A general rise of AFTs with the increasing CaO/Fe2O3 ratio was verified, especially for the Coal ash with low SiO2 + Al2O3 level and SiO2/Al2O3 mass ratio. Mullite and anorthite are main refractory minerals phase of the ash samples with high SiO2 and Al2O3 levels. The fusion of the ash in anorthite primary phase is the “soft-melting” mechanism, and liquidus temperature was well used to predict flow temperature (FT). However, the liquidus temperature should not be used to predict FT of the ash in mullite primary phase due to the “melting-dissolve” mechanism. A Tmullite model was proposed to predict FT for the ashes in mullite primary phase. The deviation of predicted and measured FT was within the measuring error range (±40 °C), which was supported by 25 real Coal ashes.
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the key for sodium rich Coal utilization in entrained flow gasifier the role of sodium on slag viscosity temperature behavior at high temperatures
Applied Energy, 2017Co-Authors: Xiaodong Chen, Lingxue Kong, Jin Bai, Xin Dai, Zongqing BaiAbstract:Abstract Tremendous sodium-rich Coal in China has unique ash compositions, and the entrained flow gasification is one of the best choices to use sodium-rich Coal for Coal chemical industry. The entrained flow gasifiers require smooth slag tapping for long term and safe running, but the viscosity-temperature behavior of high-sodium slags is unknown, which limits the utilization of sodium-rich Coal. In this study, viscosity-temperature behavior of high-sodium Coal ash slags was revealed for the first time, and the parameter of slag network structure and index of slag crystallization tendency is raised for slag viscosity evaluation. The results show that Na 2 O provides O 2− ions which break Si O Si bonds and slag network structure. However, Al 3+ ions are absorbed into silicate network, acting as a network former with the ionic charge-compensation effect of Na + . The classic structural parameter (fraction of non-bridging oxygen, NBO) is modified to evaluate the high-sodium slag viscosity accurately by taking Al 3+ into account. NBO fraction decreases as Na 2 O content increases, leading to the decrease of slag viscosity. Below T liq , slags are prone to be crystalline slag with increasing Na 2 O content or glassy slag with increase in SiO 2 /Al 2 O 3 ratio (S/A). A novel index, namely glassy slag formation ability (G), is established to quantitatively evaluate the crystallization tendency of Coal ash slags. G is the ratio of activation energy for viscous flow ( E η ) to T liq . The slag will exhibit the glassy behavior when G is higher than 0.16 kJ/(mol·K). The results enhance the knowledge of viscosity-temperature behavior of high-sodium Coal ash slags and will be helpful for Coal Selection and blending to avoid slag blockage in entrained flow gasification.
Stefan Guhl - One of the best experts on this subject based on the ideXlab platform.
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crystallization kinetics and tcv prediction of Coal ash slag under slag tapping conditions in an entrained flow gasifier
Fuel, 2020Co-Authors: Lingxue Kong, Bernd Meyer, Jin Bai, Zongqing Bai, Xi Cao, Huiling Zhao, Stefan GuhlAbstract:Abstract Slag blockages in the bottom of gasifiers cause unplanned shutdowns and huge losses for syngas utilization downstream of gasification. The sudden viscosity increase by crystal precipitation leads to slag blockage during slag tapping in entrained flow gasifiers. The temperature at which the viscosity abruptly increases is the temperature of critical viscosity (TCV), which is the strict low limit temperature for slag tapping. A comprehensive investigation of slag crystallization kinetics was performed to illustrate TCV in this work. Five slag samples with three different dominant mineral phases that commonly appear in Coal ash slag were selected by thermodynamic calculations. The single hot thermocouple technique (SHTT) was applied to analyze the crystallization kinetics based on Avrami and JMA theory. The kinetic analysis indicated that anorthite showed heterogeneous nucleation and grew with a two-dimensional crystalline pattern. The temperature range for anorthite crystallization was approximately 150 °C. Corundum exhibited heterogeneous nucleation and one-dimensional growth pattern. The maximum crystal ratio was 52% for corundum at the temperature of 98 °C. Mullite showed a low E c value, resulting in a high Ton. Rapid crystallization of mullite was observed at 60 °C due to homogeneous nucleation and two-dimensional crystallization. In this work, TCV was revealed by crystallization kinetics for the first time. The relationship between TCV and the activation energy, maximum crystalline rate, and initial crystallization temperature was built to illustrate the influence of crystallization on TCV. Three equations were used for TCV prediction to guide Coal Selection and slag tapping in entrained flow gasifiers.
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effect of cao fe2o3 ratio on fusibility of Coal ashes with high silica and alumina levels and prediction
Fuel, 2020Co-Authors: Wenju Shi, Lingxue Kong, Jin Bai, Zongqing Bai, Stefan Guhl, Huiling Zhao, Bernd MeyerAbstract:Abstract Ash fusibility which is usually investigated and evaluated by the ash chemical compositions is widely used to guide the Coal Selection in boiler and gasifier. Calcium and iron are the main basic oxides in Coal ash, which tend to decrease ash fusion temperatures (AFTs). However, the change of AFTs varied with CaO/Fe2O3 mass ratio is not yet revealed. In this work, effect of CaO/Fe2O3 ratio on the fusibility of ash with high silica and alumina levels was explored under weak reducing atmosphere (CO: CO2 = 3/2, volume ratio). Thermodynamic calculations were applied to investigate the fusion behavior. A general rise of AFTs with the increasing CaO/Fe2O3 ratio was verified, especially for the Coal ash with low SiO2 + Al2O3 level and SiO2/Al2O3 mass ratio. Mullite and anorthite are main refractory minerals phase of the ash samples with high SiO2 and Al2O3 levels. The fusion of the ash in anorthite primary phase is the “soft-melting” mechanism, and liquidus temperature was well used to predict flow temperature (FT). However, the liquidus temperature should not be used to predict FT of the ash in mullite primary phase due to the “melting-dissolve” mechanism. A Tmullite model was proposed to predict FT for the ashes in mullite primary phase. The deviation of predicted and measured FT was within the measuring error range (±40 °C), which was supported by 25 real Coal ashes.
Bernd Meyer - One of the best experts on this subject based on the ideXlab platform.
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crystallization kinetics and tcv prediction of Coal ash slag under slag tapping conditions in an entrained flow gasifier
Fuel, 2020Co-Authors: Lingxue Kong, Bernd Meyer, Jin Bai, Zongqing Bai, Xi Cao, Huiling Zhao, Stefan GuhlAbstract:Abstract Slag blockages in the bottom of gasifiers cause unplanned shutdowns and huge losses for syngas utilization downstream of gasification. The sudden viscosity increase by crystal precipitation leads to slag blockage during slag tapping in entrained flow gasifiers. The temperature at which the viscosity abruptly increases is the temperature of critical viscosity (TCV), which is the strict low limit temperature for slag tapping. A comprehensive investigation of slag crystallization kinetics was performed to illustrate TCV in this work. Five slag samples with three different dominant mineral phases that commonly appear in Coal ash slag were selected by thermodynamic calculations. The single hot thermocouple technique (SHTT) was applied to analyze the crystallization kinetics based on Avrami and JMA theory. The kinetic analysis indicated that anorthite showed heterogeneous nucleation and grew with a two-dimensional crystalline pattern. The temperature range for anorthite crystallization was approximately 150 °C. Corundum exhibited heterogeneous nucleation and one-dimensional growth pattern. The maximum crystal ratio was 52% for corundum at the temperature of 98 °C. Mullite showed a low E c value, resulting in a high Ton. Rapid crystallization of mullite was observed at 60 °C due to homogeneous nucleation and two-dimensional crystallization. In this work, TCV was revealed by crystallization kinetics for the first time. The relationship between TCV and the activation energy, maximum crystalline rate, and initial crystallization temperature was built to illustrate the influence of crystallization on TCV. Three equations were used for TCV prediction to guide Coal Selection and slag tapping in entrained flow gasifiers.
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effect of cao fe2o3 ratio on fusibility of Coal ashes with high silica and alumina levels and prediction
Fuel, 2020Co-Authors: Wenju Shi, Lingxue Kong, Jin Bai, Zongqing Bai, Stefan Guhl, Huiling Zhao, Bernd MeyerAbstract:Abstract Ash fusibility which is usually investigated and evaluated by the ash chemical compositions is widely used to guide the Coal Selection in boiler and gasifier. Calcium and iron are the main basic oxides in Coal ash, which tend to decrease ash fusion temperatures (AFTs). However, the change of AFTs varied with CaO/Fe2O3 mass ratio is not yet revealed. In this work, effect of CaO/Fe2O3 ratio on the fusibility of ash with high silica and alumina levels was explored under weak reducing atmosphere (CO: CO2 = 3/2, volume ratio). Thermodynamic calculations were applied to investigate the fusion behavior. A general rise of AFTs with the increasing CaO/Fe2O3 ratio was verified, especially for the Coal ash with low SiO2 + Al2O3 level and SiO2/Al2O3 mass ratio. Mullite and anorthite are main refractory minerals phase of the ash samples with high SiO2 and Al2O3 levels. The fusion of the ash in anorthite primary phase is the “soft-melting” mechanism, and liquidus temperature was well used to predict flow temperature (FT). However, the liquidus temperature should not be used to predict FT of the ash in mullite primary phase due to the “melting-dissolve” mechanism. A Tmullite model was proposed to predict FT for the ashes in mullite primary phase. The deviation of predicted and measured FT was within the measuring error range (±40 °C), which was supported by 25 real Coal ashes.