The gas-liquid-solid fluidized bed has emerged in recent years as one of the most promising devices for three-phase operation. Selection and design is one of them in parameter in the performance of three phase system....The gas-liquid-solid fluidized bed has emerged in recent years as one of the most promising devices for three-phase operation. Selection and design is one of them in parameter in the performance of three phase system. This paper focuses on volume fraction and density effect on the phases hold-up in a 3 phase fluidize bed column containing liquid phase with 100 cm height and 20 cm diameter, in this case the solid phase with 0.15, 0.25, 0.35 volume fraction and density 2470, 3000, 4000, 5000 m3 dispersion into liquid phase and the gas phase enter the column through a sparger of 2 cm diameter with 0.02 m/s velocities. The results show as the solid phase volume fraction increases from 0.02 to 0.08 m/s. The gas hold-up decreases and solid hold-up increases. Solid phase density increases, so solid phase hold-up decreases and gas hold-up decreases.展开更多
The liquid hold-up in a reactive distillation(RD)column not only has a significant impact on the extent of reactions,but also affects the pressure drop and hydraulic conditions in the column.Therefore,the liquid hold-...The liquid hold-up in a reactive distillation(RD)column not only has a significant impact on the extent of reactions,but also affects the pressure drop and hydraulic conditions in the column.Therefore,the liquid hold-up would be a critical design factor for RD columns.However,the existing design methods for RD columns typically neglect the influence of considerable amount of liquid hold-up in downcomers owing to the difficulties of solving a large-scale nonlinear model system by considering downcomer hydraulics,resulting in significant deviations from actual situation and even operation infeasibility of the designed column.In this paper,a pseudo-transient(PT)RD model based on equilibrium model considering tray hydraulics was established for rigorous simulation and optimization of RD plate columns considering the liquid hold-up both in downcomers and column trays,and a steady-state optimization algorithm assisted by the PT model was adopted to robustly solve the optimization problem.The optimization results of either ethylene glycol RD or methyl acetate RD demonstrated that assuming all the liquid hold-up of a stage belonged to the tray will cause significant deviations in the column diameter,weir height,and the number of stages,which leads to not meeting the separation requirements and even operation hydraulic infeasibility.The rigorous model proposed in this study which considers the liquid hold-up both on trays and in downcomers as well as hydraulic constraints can be applied to systematically design industrial RD plate columns to simultaneously obtain optimal operating variables and equipment structure variables.展开更多
Characterizing the hydrodynamics of a fluidized bed flotation column is essential for understanding the behavior of this multiphase flow system.Bed pressure fluctuations and phase hold-ups are two of these key charact...Characterizing the hydrodynamics of a fluidized bed flotation column is essential for understanding the behavior of this multiphase flow system.Bed pressure fluctuations and phase hold-ups are two of these key characteristics.Static bed height effects on these two key characteristics were comprehensively studied using experimental and statistical analysis operating for different flow regimes.And three different bed height-to-diameter ratios(H/D=1.0,1.5,and 2.0)were investigated.The time series signals of pressure fluctuation were recorded via a pressure transducer,then analyzed through time and frequency domain methods.Cross-sectional and radial combined gas and solid hold-ups distribution were detected through the electrical resistance tomography under different H/D ratios.Results indicated that the key parameters of bed pressure fluctuation signals and gas-solid hold-up distributions are significantly affected by the change in static bed height,which can be explained by differences in bubble dynamics and particle movement behaviors.展开更多
文摘The gas-liquid-solid fluidized bed has emerged in recent years as one of the most promising devices for three-phase operation. Selection and design is one of them in parameter in the performance of three phase system. This paper focuses on volume fraction and density effect on the phases hold-up in a 3 phase fluidize bed column containing liquid phase with 100 cm height and 20 cm diameter, in this case the solid phase with 0.15, 0.25, 0.35 volume fraction and density 2470, 3000, 4000, 5000 m3 dispersion into liquid phase and the gas phase enter the column through a sparger of 2 cm diameter with 0.02 m/s velocities. The results show as the solid phase volume fraction increases from 0.02 to 0.08 m/s. The gas hold-up decreases and solid hold-up increases. Solid phase density increases, so solid phase hold-up decreases and gas hold-up decreases.
基金supported by the National Natural Science Foundation of China(22378304).
文摘The liquid hold-up in a reactive distillation(RD)column not only has a significant impact on the extent of reactions,but also affects the pressure drop and hydraulic conditions in the column.Therefore,the liquid hold-up would be a critical design factor for RD columns.However,the existing design methods for RD columns typically neglect the influence of considerable amount of liquid hold-up in downcomers owing to the difficulties of solving a large-scale nonlinear model system by considering downcomer hydraulics,resulting in significant deviations from actual situation and even operation infeasibility of the designed column.In this paper,a pseudo-transient(PT)RD model based on equilibrium model considering tray hydraulics was established for rigorous simulation and optimization of RD plate columns considering the liquid hold-up both in downcomers and column trays,and a steady-state optimization algorithm assisted by the PT model was adopted to robustly solve the optimization problem.The optimization results of either ethylene glycol RD or methyl acetate RD demonstrated that assuming all the liquid hold-up of a stage belonged to the tray will cause significant deviations in the column diameter,weir height,and the number of stages,which leads to not meeting the separation requirements and even operation hydraulic infeasibility.The rigorous model proposed in this study which considers the liquid hold-up both on trays and in downcomers as well as hydraulic constraints can be applied to systematically design industrial RD plate columns to simultaneously obtain optimal operating variables and equipment structure variables.
基金funded by Basic Research Program of Jiangsu(grant Nos.BK20240106 and BK20240014)National Natural Science Foundation of China(grant Nos.52174265,52425407,and 52274278).
文摘Characterizing the hydrodynamics of a fluidized bed flotation column is essential for understanding the behavior of this multiphase flow system.Bed pressure fluctuations and phase hold-ups are two of these key characteristics.Static bed height effects on these two key characteristics were comprehensively studied using experimental and statistical analysis operating for different flow regimes.And three different bed height-to-diameter ratios(H/D=1.0,1.5,and 2.0)were investigated.The time series signals of pressure fluctuation were recorded via a pressure transducer,then analyzed through time and frequency domain methods.Cross-sectional and radial combined gas and solid hold-ups distribution were detected through the electrical resistance tomography under different H/D ratios.Results indicated that the key parameters of bed pressure fluctuation signals and gas-solid hold-up distributions are significantly affected by the change in static bed height,which can be explained by differences in bubble dynamics and particle movement behaviors.
