The Experts below are selected from a list of 3720 Experts worldwide ranked by ideXlab platform
Haifeng Liu - One of the best experts on this subject based on the ideXlab platform.
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Modeling the slag flow and heat transfer on the bottom cone of a membrane wall entrained-flow gasifier
Fuel, 2018Co-Authors: Binbin Zhang, Qinfeng Liang, Zhongjie Shen, Haifeng LiuAbstract:Abstract The slag behaviors on the bottom cone are crucial characteristics that relate to the slag blockage in a gasifier. The slag flow and heat transfer model on the bottom cone was built to calculate the slag flow velocity, slag thickness and heat flux density. The results shown the slag flow velocity decreased and the slag thickness increased with the increasing cone angle. The slag heat flux density decreased with the increasing cone angle, and specially, the heat transfer rate of the overall bottom cone decreased significantly with the increasing cone angle. The flow slag residence time model was established to calculate the residence time distribution (RTD) of molten slag, and the results shown the mean residence time decreased with the increasing cone angle. In addition, this study preliminary analyzed the blockage possibility, and the results shown the slag thickness was significantly influenced by the critical temperature interval.
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Effects of the bubbles in slag on slag flow and heat transfer in the membrane wall entrained-flow gasifier
Applied Thermal Engineering, 2017Co-Authors: Binbin Zhang, Qinfeng Liang, Zhongjie Shen, Dong Han, Haifeng LiuAbstract:Abstract The slag from the industrial gasifier has porous structure, which has a non-ignorable influence on the characteristics of slag layer. The slag flow and heat transfer model were modified based on the effective thermal conductivity and viscosity, to predict the slag characteristics for the effects of bubbles in slag. The results show that bubbles inside slag reduce the slag thermal conductivity and viscosity. The modified model predicts the liquid slag velocity, slag layer thickness and heat flux of slag layer. The liquid slag flow velocity increases with the increase of bubbles inside slag, while the thickness of slag layer decreases. In addition, the increasing gas volume fraction of bubbles inside slag decreases the heat flux of slag layer. Two models are applied to calculate the bubbly slag effective thermal conductivity. The Maxwell-Eucken thermal conductivity model is more accurate than geometric mean model from the result of slag layer heat flux.
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Modeling the slag flow and heat transfer with the effect of fluid-solid slag layer interface viscosity in an entrained flow gasifier
Applied Thermal Engineering, 2017Co-Authors: Binbin Zhang, Qinfeng Liang, Zhongjie Shen, Haifeng LiuAbstract:Abstract The characteristics of slag flow and heat transfer in a gasifier are significant for controlling the operation conditions. Determination of the fluid-solid slag layer interface is a crucial procedure in the studying of slag flow and heat transfer characteristics. The varied absolute viscosities were used as the fluid-solid slag layer interface viscosity to model the slag layer properties in an entrained flow gasifier. The results showed that with the increase of fluid-solid slag layer interface viscosity, the liquid slag layer thickness increased, while the solid slag layer thickness and the liquid slag velocity decreased. Moreover, the slag layer overall thickness had a slight decrease, while the slag heat flux had a slight increase. In addition, the effects of the fluid-solid slag layer interface viscosity on slag layer characteristics with glassy slag and plastic slag were relatively higher than crystalline slag. The smoother the viscosity-temperature profile, the higher the influences of the fluid-solid slag layers interface viscosity. The critical viscosity could be approximate regarded as the fluid-solid slag layer interface viscosity when the slag type was crystalline slag during the model derivation, and the fluid-solid interface viscosity can be defined as about 100 Pa s for plastic slag and glassy slag.
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Experimental and numerical study on slag deposition and growth at the slag tap hole region of Shell gasifier
Fuel Processing Technology, 2013Co-Authors: Jian Wang, Haifeng Liu, Qinfeng LiangAbstract:Abstract Cold model experimental and dynamic modeling studies on the slag flow and heat transfer at the slag tap hole region of Shell gasifier have been carried out. The cold model experiment was set up to observe the simulated slag deposition. The dynamic model was proposed to clarify the slag accumulation on the wall of slag screen. The results show that the simulated slag can be broken up to slender liquid filaments by the high-speed swirling gas flow, and a part of the filaments can deposit on the slag screen wall. When the surface temperature is below the critical temperature, the slag is totally solidified to solid slag layer. At equilibrium, a liquid slag layer covers the solid slag layer and its surface temperature is higher than the critical temperature. The solid slag layer thickness increases along the slag flow. In addition, the solid slag thickness can be decreased by increasing the operating load and operating temperature.
Qinfeng Liang - One of the best experts on this subject based on the ideXlab platform.
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Modeling the slag flow and heat transfer on the bottom cone of a membrane wall entrained-flow gasifier
Fuel, 2018Co-Authors: Binbin Zhang, Qinfeng Liang, Zhongjie Shen, Haifeng LiuAbstract:Abstract The slag behaviors on the bottom cone are crucial characteristics that relate to the slag blockage in a gasifier. The slag flow and heat transfer model on the bottom cone was built to calculate the slag flow velocity, slag thickness and heat flux density. The results shown the slag flow velocity decreased and the slag thickness increased with the increasing cone angle. The slag heat flux density decreased with the increasing cone angle, and specially, the heat transfer rate of the overall bottom cone decreased significantly with the increasing cone angle. The flow slag residence time model was established to calculate the residence time distribution (RTD) of molten slag, and the results shown the mean residence time decreased with the increasing cone angle. In addition, this study preliminary analyzed the blockage possibility, and the results shown the slag thickness was significantly influenced by the critical temperature interval.
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Effects of the bubbles in slag on slag flow and heat transfer in the membrane wall entrained-flow gasifier
Applied Thermal Engineering, 2017Co-Authors: Binbin Zhang, Qinfeng Liang, Zhongjie Shen, Dong Han, Haifeng LiuAbstract:Abstract The slag from the industrial gasifier has porous structure, which has a non-ignorable influence on the characteristics of slag layer. The slag flow and heat transfer model were modified based on the effective thermal conductivity and viscosity, to predict the slag characteristics for the effects of bubbles in slag. The results show that bubbles inside slag reduce the slag thermal conductivity and viscosity. The modified model predicts the liquid slag velocity, slag layer thickness and heat flux of slag layer. The liquid slag flow velocity increases with the increase of bubbles inside slag, while the thickness of slag layer decreases. In addition, the increasing gas volume fraction of bubbles inside slag decreases the heat flux of slag layer. Two models are applied to calculate the bubbly slag effective thermal conductivity. The Maxwell-Eucken thermal conductivity model is more accurate than geometric mean model from the result of slag layer heat flux.
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Modeling the slag flow and heat transfer with the effect of fluid-solid slag layer interface viscosity in an entrained flow gasifier
Applied Thermal Engineering, 2017Co-Authors: Binbin Zhang, Qinfeng Liang, Zhongjie Shen, Haifeng LiuAbstract:Abstract The characteristics of slag flow and heat transfer in a gasifier are significant for controlling the operation conditions. Determination of the fluid-solid slag layer interface is a crucial procedure in the studying of slag flow and heat transfer characteristics. The varied absolute viscosities were used as the fluid-solid slag layer interface viscosity to model the slag layer properties in an entrained flow gasifier. The results showed that with the increase of fluid-solid slag layer interface viscosity, the liquid slag layer thickness increased, while the solid slag layer thickness and the liquid slag velocity decreased. Moreover, the slag layer overall thickness had a slight decrease, while the slag heat flux had a slight increase. In addition, the effects of the fluid-solid slag layer interface viscosity on slag layer characteristics with glassy slag and plastic slag were relatively higher than crystalline slag. The smoother the viscosity-temperature profile, the higher the influences of the fluid-solid slag layers interface viscosity. The critical viscosity could be approximate regarded as the fluid-solid slag layer interface viscosity when the slag type was crystalline slag during the model derivation, and the fluid-solid interface viscosity can be defined as about 100 Pa s for plastic slag and glassy slag.
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Experimental and numerical study on slag deposition and growth at the slag tap hole region of Shell gasifier
Fuel Processing Technology, 2013Co-Authors: Jian Wang, Haifeng Liu, Qinfeng LiangAbstract:Abstract Cold model experimental and dynamic modeling studies on the slag flow and heat transfer at the slag tap hole region of Shell gasifier have been carried out. The cold model experiment was set up to observe the simulated slag deposition. The dynamic model was proposed to clarify the slag accumulation on the wall of slag screen. The results show that the simulated slag can be broken up to slender liquid filaments by the high-speed swirling gas flow, and a part of the filaments can deposit on the slag screen wall. When the surface temperature is below the critical temperature, the slag is totally solidified to solid slag layer. At equilibrium, a liquid slag layer covers the solid slag layer and its surface temperature is higher than the critical temperature. The solid slag layer thickness increases along the slag flow. In addition, the solid slag thickness can be decreased by increasing the operating load and operating temperature.
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Molten Slag Flow and Phase Transformation Behaviors in a Slagging Entrained-Flow Coal Gasifier
Industrial & Engineering Chemistry Research, 2010Co-Authors: Zhijie Zhou, Qinfeng Liang, Fuchen WangAbstract:A slag flow submodel has been developed to simulate the slag flow and phase transformation behaviors in coal gasifiers. The volume of the fluid (VOF) model is used to capture the free surface of the slag flow, and the continuum surface force (CSF) model is employed to calculate the surface tension between the gas phase and the liquid slag phase. The slag is treated as a Newtonian fluid when the slag temperature is above the critical viscosity temperature (Tcv), and plastic fluid is treated when the slag temperature is between the flow temperature (Tf) and the Tcv. The ash particle deposition, viscosity−temperature dependence, and different thermal conductivity for different slag phase are all included in the present simulation. For membrane wall coal gasification, the liquid slag and solid slag layer increases along the flow and total slag thickness increases as the operating temperature decreases. The velocity profiles and viscosity profiles at different operating temperatures are performed. The liquid s...
Binbin Zhang - One of the best experts on this subject based on the ideXlab platform.
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Modeling the slag flow and heat transfer on the bottom cone of a membrane wall entrained-flow gasifier
Fuel, 2018Co-Authors: Binbin Zhang, Qinfeng Liang, Zhongjie Shen, Haifeng LiuAbstract:Abstract The slag behaviors on the bottom cone are crucial characteristics that relate to the slag blockage in a gasifier. The slag flow and heat transfer model on the bottom cone was built to calculate the slag flow velocity, slag thickness and heat flux density. The results shown the slag flow velocity decreased and the slag thickness increased with the increasing cone angle. The slag heat flux density decreased with the increasing cone angle, and specially, the heat transfer rate of the overall bottom cone decreased significantly with the increasing cone angle. The flow slag residence time model was established to calculate the residence time distribution (RTD) of molten slag, and the results shown the mean residence time decreased with the increasing cone angle. In addition, this study preliminary analyzed the blockage possibility, and the results shown the slag thickness was significantly influenced by the critical temperature interval.
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Effects of the bubbles in slag on slag flow and heat transfer in the membrane wall entrained-flow gasifier
Applied Thermal Engineering, 2017Co-Authors: Binbin Zhang, Qinfeng Liang, Zhongjie Shen, Dong Han, Haifeng LiuAbstract:Abstract The slag from the industrial gasifier has porous structure, which has a non-ignorable influence on the characteristics of slag layer. The slag flow and heat transfer model were modified based on the effective thermal conductivity and viscosity, to predict the slag characteristics for the effects of bubbles in slag. The results show that bubbles inside slag reduce the slag thermal conductivity and viscosity. The modified model predicts the liquid slag velocity, slag layer thickness and heat flux of slag layer. The liquid slag flow velocity increases with the increase of bubbles inside slag, while the thickness of slag layer decreases. In addition, the increasing gas volume fraction of bubbles inside slag decreases the heat flux of slag layer. Two models are applied to calculate the bubbly slag effective thermal conductivity. The Maxwell-Eucken thermal conductivity model is more accurate than geometric mean model from the result of slag layer heat flux.
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Modeling the slag flow and heat transfer with the effect of fluid-solid slag layer interface viscosity in an entrained flow gasifier
Applied Thermal Engineering, 2017Co-Authors: Binbin Zhang, Qinfeng Liang, Zhongjie Shen, Haifeng LiuAbstract:Abstract The characteristics of slag flow and heat transfer in a gasifier are significant for controlling the operation conditions. Determination of the fluid-solid slag layer interface is a crucial procedure in the studying of slag flow and heat transfer characteristics. The varied absolute viscosities were used as the fluid-solid slag layer interface viscosity to model the slag layer properties in an entrained flow gasifier. The results showed that with the increase of fluid-solid slag layer interface viscosity, the liquid slag layer thickness increased, while the solid slag layer thickness and the liquid slag velocity decreased. Moreover, the slag layer overall thickness had a slight decrease, while the slag heat flux had a slight increase. In addition, the effects of the fluid-solid slag layer interface viscosity on slag layer characteristics with glassy slag and plastic slag were relatively higher than crystalline slag. The smoother the viscosity-temperature profile, the higher the influences of the fluid-solid slag layers interface viscosity. The critical viscosity could be approximate regarded as the fluid-solid slag layer interface viscosity when the slag type was crystalline slag during the model derivation, and the fluid-solid interface viscosity can be defined as about 100 Pa s for plastic slag and glassy slag.
Zhongjie Shen - One of the best experts on this subject based on the ideXlab platform.
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Modeling the slag flow and heat transfer on the bottom cone of a membrane wall entrained-flow gasifier
Fuel, 2018Co-Authors: Binbin Zhang, Qinfeng Liang, Zhongjie Shen, Haifeng LiuAbstract:Abstract The slag behaviors on the bottom cone are crucial characteristics that relate to the slag blockage in a gasifier. The slag flow and heat transfer model on the bottom cone was built to calculate the slag flow velocity, slag thickness and heat flux density. The results shown the slag flow velocity decreased and the slag thickness increased with the increasing cone angle. The slag heat flux density decreased with the increasing cone angle, and specially, the heat transfer rate of the overall bottom cone decreased significantly with the increasing cone angle. The flow slag residence time model was established to calculate the residence time distribution (RTD) of molten slag, and the results shown the mean residence time decreased with the increasing cone angle. In addition, this study preliminary analyzed the blockage possibility, and the results shown the slag thickness was significantly influenced by the critical temperature interval.
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Effects of the bubbles in slag on slag flow and heat transfer in the membrane wall entrained-flow gasifier
Applied Thermal Engineering, 2017Co-Authors: Binbin Zhang, Qinfeng Liang, Zhongjie Shen, Dong Han, Haifeng LiuAbstract:Abstract The slag from the industrial gasifier has porous structure, which has a non-ignorable influence on the characteristics of slag layer. The slag flow and heat transfer model were modified based on the effective thermal conductivity and viscosity, to predict the slag characteristics for the effects of bubbles in slag. The results show that bubbles inside slag reduce the slag thermal conductivity and viscosity. The modified model predicts the liquid slag velocity, slag layer thickness and heat flux of slag layer. The liquid slag flow velocity increases with the increase of bubbles inside slag, while the thickness of slag layer decreases. In addition, the increasing gas volume fraction of bubbles inside slag decreases the heat flux of slag layer. Two models are applied to calculate the bubbly slag effective thermal conductivity. The Maxwell-Eucken thermal conductivity model is more accurate than geometric mean model from the result of slag layer heat flux.
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Modeling the slag flow and heat transfer with the effect of fluid-solid slag layer interface viscosity in an entrained flow gasifier
Applied Thermal Engineering, 2017Co-Authors: Binbin Zhang, Qinfeng Liang, Zhongjie Shen, Haifeng LiuAbstract:Abstract The characteristics of slag flow and heat transfer in a gasifier are significant for controlling the operation conditions. Determination of the fluid-solid slag layer interface is a crucial procedure in the studying of slag flow and heat transfer characteristics. The varied absolute viscosities were used as the fluid-solid slag layer interface viscosity to model the slag layer properties in an entrained flow gasifier. The results showed that with the increase of fluid-solid slag layer interface viscosity, the liquid slag layer thickness increased, while the solid slag layer thickness and the liquid slag velocity decreased. Moreover, the slag layer overall thickness had a slight decrease, while the slag heat flux had a slight increase. In addition, the effects of the fluid-solid slag layer interface viscosity on slag layer characteristics with glassy slag and plastic slag were relatively higher than crystalline slag. The smoother the viscosity-temperature profile, the higher the influences of the fluid-solid slag layers interface viscosity. The critical viscosity could be approximate regarded as the fluid-solid slag layer interface viscosity when the slag type was crystalline slag during the model derivation, and the fluid-solid interface viscosity can be defined as about 100 Pa s for plastic slag and glassy slag.
Fuchen Wang - One of the best experts on this subject based on the ideXlab platform.
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Molten Slag Flow and Phase Transformation Behaviors in a Slagging Entrained-Flow Coal Gasifier
Industrial & Engineering Chemistry Research, 2010Co-Authors: Zhijie Zhou, Qinfeng Liang, Fuchen WangAbstract:A slag flow submodel has been developed to simulate the slag flow and phase transformation behaviors in coal gasifiers. The volume of the fluid (VOF) model is used to capture the free surface of the slag flow, and the continuum surface force (CSF) model is employed to calculate the surface tension between the gas phase and the liquid slag phase. The slag is treated as a Newtonian fluid when the slag temperature is above the critical viscosity temperature (Tcv), and plastic fluid is treated when the slag temperature is between the flow temperature (Tf) and the Tcv. The ash particle deposition, viscosity−temperature dependence, and different thermal conductivity for different slag phase are all included in the present simulation. For membrane wall coal gasification, the liquid slag and solid slag layer increases along the flow and total slag thickness increases as the operating temperature decreases. The velocity profiles and viscosity profiles at different operating temperatures are performed. The liquid s...
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characterisation of residual carbon from entrained bed coal water slurry gasifiers
Fuel, 2007Co-Authors: Tao Wu, Zhijie Zhou, Fuchen Wang, Mei Gong, Edward Lester, Zunhong YuAbstract:Abstract Gasification slag is a by-product of the coal gasification process. To achieve “zero emissions” from coal gasification technology, the environmentally safe utilization of slag by-products from gasifiers must be addressed and developed. In this study, work has been carried out to characterize residual carbon in slag together the morphological study on vitreous material present in slag. The compositions of particles in coal, char and slag were determined by using SEM/EDX. An elemental analyzer (Flash EA 1112) was adopted to analyze CHNS on bulk coal, char and slag. The size distribution of carbon in slag was obtained by analyzing slag sample blocks using an image analysis program developed in this study. It was found that the coarse and fine slags both have a relatively high content of unburnt carbon which hinders their utilization as additives in cement and concrete. There was no evidence that coarse slag is the final destination for coarse char particles since large unburnt chars were found in both the coarse slag and the fine slag. The morphology of the residual carbon in the coarse slag is similar to that found in the fine slag, and is also comparable to partially combusted char produced in a drop tube furnace (DTF) operating at 1300 °C, 600 ms and 2% oxygen. It is also found that the vitreous particles in fine slag tends to be below 150 μm and the majority of residual carbon (75.6 wt%) in fine slag tends to be greater than 150 μm, which implies that, a simple screening operation might make the slag usable in concrete industries.