A pilot-scale experimental setup was constructed to investigate the effect of mild agitation on the bubble characteristics and phase holdup in a slurry bubble column.Mild agitation positively impacts the axial uniform...A pilot-scale experimental setup was constructed to investigate the effect of mild agitation on the bubble characteristics and phase holdup in a slurry bubble column.Mild agitation positively impacts the axial uniform distribution of solid holdup,though it shows insignificant influence on the radial distribution.In homogenous regime,mild agitation promotes the coalescence of bubbles,and the effect becomes stronger with increasing agitator speed.The mild agitation contributes to a decrease in bubble size in heterogeneous flow regime.Mild agitation presents a significant effect on the gas holdup by adjusting the bubble size and bubble motion trajectory.The modification was introduced to predict the gas holdup considering the effects of mild agitation,a necessary consideration for applications requiring mild agitation.This adapted model predicts gas holdup with a maximum error of 12.9%.展开更多
In the present work, an experimental study of bubbly two-phase flow in a rectangular bubble column was performed using two ultrasonic array sensors, which can measure the instantaneous velocity of gas bubbles on multi...In the present work, an experimental study of bubbly two-phase flow in a rectangular bubble column was performed using two ultrasonic array sensors, which can measure the instantaneous velocity of gas bubbles on multiple measurement lines. After the sound pressure distribution of sensors had been evaluated with a needle hydrophone technique, the array sensors were applied to two-phase bubble col- umn, To assess the accuracy of the measurement system with array sensors for one and two-dimensional velocity, a simultaneous measurement was performed with an optical measurement technique called particle image velocimetry （PIV）. Experimental results showed that accuracy of the measurement system with array sensors is under 10% for one-dimensional velocity profile measurement compared with PIV technique. The accuracy of the system was estimated to be under 20% along the mean flow direction in the case of two-dimensional vector mapping.展开更多
In the present study, we developed a multi-component one-dimensional mathematical model for simulation and optimisation of a commercial catalytic slurry reactor for the direct synthesis of dimethyl ether （DME） from ...In the present study, we developed a multi-component one-dimensional mathematical model for simulation and optimisation of a commercial catalytic slurry reactor for the direct synthesis of dimethyl ether （DME） from syngas and CO2, operating in a churn-turbulent regime. DME productivity and CO conversion were optimised by tuning operating conditions, such as superficial gas velocity, catalyst concentration, catalyst mass over molar gas flow rate （W/F）, syngas composition, pressure and temperature. Reactor modelling was accomplished utilising mass balance, global kinetic models and heterogeneous hydrodynamics. In the heterogeneous flow regime, gas was distributed into two bubble phases： small and large. Simulation results were validated using data obtained from a pilot plant. The developed model is also applicable for the design of large-scale slurry reactors.展开更多
It is generally admitted that experimental data obtained in“laboratory-scale”bubble columns are representative of“industrial-scale”reactors if the well-known three“Wilkinson et al.scale-up criteria”are satisfied...It is generally admitted that experimental data obtained in“laboratory-scale”bubble columns are representative of“industrial-scale”reactors if the well-known three“Wilkinson et al.scale-up criteria”are satisfied:(a)the diameter of the bubble column is larger than 0.15 m,(b)the sparger openings are larger than 1e2mm and(c)the aspect ratio is larger than 5.The aim of this communication is to contribute to the existing discussion.To this end,this communication collects relevant experimental investigation and include new experimental data:in particular,we have experimentally studied the combined effect of the aspect ratio(within the range of 1e15)and the sparger design(considering both“coarse”and“fine”spargers)on the gas holdup in a large-diameter and large-scale gas-liquid bubble column.The bubble column has been operated both in the batch mode and in the counter-current mode.Filtered air has been used as the gaseous phase in all the experiments,while the liquid phase has included deionized water and different aqueous solutions of organic(i.e.,ethanol)and inorganic(i.e.,sodium chloride,NaCl)active agents.It is found that the“Wilkinson et al.scale-up criteria”are valid for the air-water case in the batch mode for“very-coarse”spargers.Conversely,they are no more valid when considering different liquid velocity,and/or aqueous solutions of active agents,and other sparger openings.展开更多
基金supported by National Natural Science Foundation of China(grant Nos.22308171,21968023)State Key Laboratory of Heavy Oil Processing,China University of Petroleum(grant No.WX20230157)Special Projects of the Central Government Guiding Local Science and Technology Development(grant No.2022FRD05017).
文摘A pilot-scale experimental setup was constructed to investigate the effect of mild agitation on the bubble characteristics and phase holdup in a slurry bubble column.Mild agitation positively impacts the axial uniform distribution of solid holdup,though it shows insignificant influence on the radial distribution.In homogenous regime,mild agitation promotes the coalescence of bubbles,and the effect becomes stronger with increasing agitator speed.The mild agitation contributes to a decrease in bubble size in heterogeneous flow regime.Mild agitation presents a significant effect on the gas holdup by adjusting the bubble size and bubble motion trajectory.The modification was introduced to predict the gas holdup considering the effects of mild agitation,a necessary consideration for applications requiring mild agitation.This adapted model predicts gas holdup with a maximum error of 12.9%.
文摘In the present work, an experimental study of bubbly two-phase flow in a rectangular bubble column was performed using two ultrasonic array sensors, which can measure the instantaneous velocity of gas bubbles on multiple measurement lines. After the sound pressure distribution of sensors had been evaluated with a needle hydrophone technique, the array sensors were applied to two-phase bubble col- umn, To assess the accuracy of the measurement system with array sensors for one and two-dimensional velocity, a simultaneous measurement was performed with an optical measurement technique called particle image velocimetry （PIV）. Experimental results showed that accuracy of the measurement system with array sensors is under 10% for one-dimensional velocity profile measurement compared with PIV technique. The accuracy of the system was estimated to be under 20% along the mean flow direction in the case of two-dimensional vector mapping.
文摘In the present study, we developed a multi-component one-dimensional mathematical model for simulation and optimisation of a commercial catalytic slurry reactor for the direct synthesis of dimethyl ether （DME） from syngas and CO2, operating in a churn-turbulent regime. DME productivity and CO conversion were optimised by tuning operating conditions, such as superficial gas velocity, catalyst concentration, catalyst mass over molar gas flow rate （W/F）, syngas composition, pressure and temperature. Reactor modelling was accomplished utilising mass balance, global kinetic models and heterogeneous hydrodynamics. In the heterogeneous flow regime, gas was distributed into two bubble phases： small and large. Simulation results were validated using data obtained from a pilot plant. The developed model is also applicable for the design of large-scale slurry reactors.
文摘It is generally admitted that experimental data obtained in“laboratory-scale”bubble columns are representative of“industrial-scale”reactors if the well-known three“Wilkinson et al.scale-up criteria”are satisfied:(a)the diameter of the bubble column is larger than 0.15 m,(b)the sparger openings are larger than 1e2mm and(c)the aspect ratio is larger than 5.The aim of this communication is to contribute to the existing discussion.To this end,this communication collects relevant experimental investigation and include new experimental data:in particular,we have experimentally studied the combined effect of the aspect ratio(within the range of 1e15)and the sparger design(considering both“coarse”and“fine”spargers)on the gas holdup in a large-diameter and large-scale gas-liquid bubble column.The bubble column has been operated both in the batch mode and in the counter-current mode.Filtered air has been used as the gaseous phase in all the experiments,while the liquid phase has included deionized water and different aqueous solutions of organic(i.e.,ethanol)and inorganic(i.e.,sodium chloride,NaCl)active agents.It is found that the“Wilkinson et al.scale-up criteria”are valid for the air-water case in the batch mode for“very-coarse”spargers.Conversely,they are no more valid when considering different liquid velocity,and/or aqueous solutions of active agents,and other sparger openings.
