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
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
将HPGeγ谱仪应用于评估放射性管道内过滤器滞留量,需要知道探测器对过滤器内 γ辐射的绝对效率。根据 Monte Carlo 模拟光子输运过程的理论,对过滤器内 γ辐射的自吸收因子、路径上物质吸收因子、几何因子和晶体中的能量沉积等进行了...将HPGeγ谱仪应用于评估放射性管道内过滤器滞留量,需要知道探测器对过滤器内 γ辐射的绝对效率。根据 Monte Carlo 模拟光子输运过程的理论,对过滤器内 γ辐射的自吸收因子、路径上物质吸收因子、几何因子和晶体中的能量沉积等进行了描述。研究表明,实验检验模拟结果不确定度小于 10%。展开更多
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.
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.
