This paper shows that one-dimensional(1-D) [and three-dimensional(3-D) computational fluid dynamics(CFD)] simulations can replace the state-of-the-art usage of pseudo-homogeneous dispersion or back mixing models.This ...This paper shows that one-dimensional(1-D) [and three-dimensional(3-D) computational fluid dynamics(CFD)] simulations can replace the state-of-the-art usage of pseudo-homogeneous dispersion or back mixing models.This is based on standardized lab-scale cell experiments for the determination of droplet rise,breakage,coalescence and mass transfer parameters in addition to a limited number of additional mini-plant experiments with original fluids.Alternatively,the hydrodynamic parameters can also be derived using more sophisticated 3-D CFD simulations.Computational 1-D modeling served as a basis to replace pilot-plant experiments in any column geometry.The combination of 3-D CFD simulations with droplet population balance models(DPBM)increased the accuracy of the hydrodynamic simulations and gave information about the local droplet size.The high computational costs can be reduced by open source CFD codes when using a flexible mesh generation.First combined simulations using a three way coupled CFD/DPBM/mass-transfer solver pave the way for a safer design of industrial-sized columns,where no correlations are available.展开更多
The technique state to design counter-current extraction columns is based on the performance of pilot plant experiments. The modelling is then either with the equilibrium or dispersion model, whereas in the latter the...The technique state to design counter-current extraction columns is based on the performance of pilot plant experiments. The modelling is then either with the equilibrium or dispersion model, whereas in the latter the dispersion coefficient accounts for all hydrodynamic non-idealities. A new approach uses single droplet experiments to obtain the basic laws and functions governing droplet breakage, coalescence, relative velocity, and axial dispersion when using droplet populance balance models （DPBM）. The hydrodynamics simulation results show that the mean Sauter diameter, hold-up, and concentration profiles could be well predicted, which promotes the use of DPBM models for further applications in industrial scale.展开更多
Reactive distillation and dividing wall column distillation are two kinds of effective separation technologies,and their integrated configuration,reactive dividing wall column(RDWC),presents attractive advantages.In t...Reactive distillation and dividing wall column distillation are two kinds of effective separation technologies,and their integrated configuration,reactive dividing wall column(RDWC),presents attractive advantages.In this study,the rigorous simulation of RDWC for methyl acetate hydrolysis is performed,and sensitivity analysis is conducted to obtain the minimum reboiler duty.Then a comparison is made between the conventional process and RDWC process,and it shows that 20.1% energy savings can be achieved by RDWC process.In addition,the dynamic characteristic of RDWC is studied and an effective control strategy is proposed.The simple PI control scheme with three temperature loops can obtain reasonable control performance and maintain products at desired purities.It is proved that this RDWC process is an energy efficiency alternative with good controllability.展开更多
The Sargent dividing wall column can implement four products separation sequences in one column based on Fully Thermally Coupled Distillation Column. The initial design parameters are required for the design optimizat...The Sargent dividing wall column can implement four products separation sequences in one column based on Fully Thermally Coupled Distillation Column. The initial design parameters are required for the design optimization or dynamic control of the Sargent dividing wall column, and in order to make the rigorous simulation of the Sargent dividing wall column more conducive to convergence, a ten column model for complex Sargent column is established in this paper,and the shortcut design method of this model is proposed. The internal minimum vapor and liquid flow are obtained by the Underwood equations and the mass balance method and the V-min method. The separation for a 4-component shortcut mixture of pentane, hexane, heptane and octane was considered, while the initial values of design parameters and the ratio of vapor-liquid distribution of each column were calculated by using the shortcut design method of a ten column model. And by comparing the shortcut calculations with rigorous simulation results, the practicality and reliability of shortcut calculations were verified. The reason for energy saving was analyzed based on back-mixing. A virtual heat exchanger is proposed to make the Sargent dividing wall column more energy efficient.展开更多
Isoamylene from the Fischer-Tropsch syncrude can be transformed to valuable fuel oxygenate additives through an equilibrium limited etherification reaction with methanol. A reactive distillation process is established...Isoamylene from the Fischer-Tropsch syncrude can be transformed to valuable fuel oxygenate additives through an equilibrium limited etherification reaction with methanol. A reactive distillation process is established to increase isoamylene conversion. Facing the challenge of improving product purity at the same time, an equilibrium stage model based design methodology is proposed and illustrated step-by-step for converting the Fischer-Tropsch C_5 olefins to tert-amyl methyl ether(TAME) process by using Aspen Plus. Under the guide of the proposed methodology, the design leads to a TAME product purity of higher than 95% and an isoamylene conversion of higher than 90%. The etherification kinetics over Amberlyst 35 is also studied within a temperature range of 60 ℃ to 75 ℃ to shed more light on the feasibility of process development. The methodology provides an effective reactive distillation column design to achieve the target reactant conversion and product purity simultaneously.展开更多
This use of biomass-based adsorbent has been explored for the column study of the adsorptive dehydration of water in ethanol-water mixtures. The column study was carried out using enzyme modified corn starch and the b...This use of biomass-based adsorbent has been explored for the column study of the adsorptive dehydration of water in ethanol-water mixtures. The column study was carried out using enzyme modified corn starch and the breakthrough curve parameters were used to design the packed bed column. The effect of flow rate on the breakthrough curves revealed that adsorption efficiency decreased with increased inflow rate. The empty bed contact time (τ) of the pilot plant packed column was 35.35 min while the breakthrough time is 40.78 min. 66.7% was the fraction of capacity left unused for the pilot plant from the design.展开更多
The effects of equipment parameters of batch distillation column on the yield proportion are discussed and analyzed, the relations between maximal yield proportion and the column equipment parameters are correlated, w...The effects of equipment parameters of batch distillation column on the yield proportion are discussed and analyzed, the relations between maximal yield proportion and the column equipment parameters are correlated, which not only can be used to appraise rationality of the design parameters of the columns being employed and which but also can be used to new batch distillation column design. Under the assistance of the separation difficulty defined in this paper, the minimum number of theoretical plates is determined by the limit loss proportion method given, and further the actual number of theoretical plates and the height for the batch distillation are calculated by using the redundancy coefficient found to complete the whole design of the batch distillation as shown in the computational sample. Research showed that the actual number of theoretical plates and the height of batch distillation column with the column diameter 0.6 m are 17 and 5.1 m in alcohol mixture separation system of the sample proposed. Moreover, the approach can be extended to the design of batch distillation column with a separation system of multi-component liquid mixture after those adjacent components are treated as numerous binary component systems.展开更多
Four types of seismic design details were tested using 11 transfer column specimens and one comparison specimen of RC under low cyclic reversed loading. Test results show that diagonal cracks control the failure patte...Four types of seismic design details were tested using 11 transfer column specimens and one comparison specimen of RC under low cyclic reversed loading. Test results show that diagonal cracks control the failure pattern and damage occurs mainly in the RC section with weak shear capacity in the transfer columns. There is a large difference in the bearing capacity and ductility of the transfer columns according to the test results, which indicates that the strengthening effect of diverse structural measures is quite different. The section ratio of I-section-encased steel and the axial compression ratio also have a great influence on the bearing capacity and ductility. Although the bearing capacity of transfer columns with additional longitudinal bars and additional X bars is relatively large, they have poor deformation capacity. Setting more stirrups along the columns is the best structural measure to enhance the seismic performance. The studs on the I-sectionencased steel by welding can help to complete the stress transfer between the steel and concrete, and avoid performance degradation of the two materials due to bonding failure.展开更多
This research work investigated comparative studies of expert system design and control of crude oil distillation column (CODC) using artificial neural networks based Monte Carlo (ANNBMC) simulation of random processe...This research work investigated comparative studies of expert system design and control of crude oil distillation column (CODC) using artificial neural networks based Monte Carlo (ANNBMC) simulation of random processes and artificial neural networks (ANN) model which were validated using experimental data obtained from functioning crude oil distillation column of Port-Harcourt Refinery, Nigeria by MATLAB computer program. Ninety percent (90%) of the experimental data sets were used for training while ten percent (10%) were used for testing the networks. The maximum relative errors between the experimental and calculated data obtained from the output variables of the neural network for CODC design were 1.98 error % and 0.57 error % when ANN only and ANNBMC were used respectively while their respective values for the maximum relative error were 0.346 error % and 0.124 error % when they were used for the controller prediction. Larger number of iteration steps of below 2500 and 5000 were required to achieve convergence of less than 10-7?for the training error using ANNBMC for both the design of the CODC and controller respectively while less than 400 and 700 iteration steps were needed to achieve convergence of 10-4?using ANN only. The linear regression analysis performed revealed the minimum and maximum prediction accuracies to be 80.65% and 98.79%;and 98.38% and 99.98% when ANN and ANNBMC were used for the CODC design respectively. Also, the minimum and maximum prediction accuracies were 92.83% and 99.34%;and 98.89% and 99.71% when ANN and ANNBMC were used for the CODC controller respectively as both methodologies have excellent predictions. Hence, artificial neural networks based Monte Carlo simulation is an effective and better tool for the design and control of crude oil distillation column.展开更多
文摘This paper shows that one-dimensional(1-D) [and three-dimensional(3-D) computational fluid dynamics(CFD)] simulations can replace the state-of-the-art usage of pseudo-homogeneous dispersion or back mixing models.This is based on standardized lab-scale cell experiments for the determination of droplet rise,breakage,coalescence and mass transfer parameters in addition to a limited number of additional mini-plant experiments with original fluids.Alternatively,the hydrodynamic parameters can also be derived using more sophisticated 3-D CFD simulations.Computational 1-D modeling served as a basis to replace pilot-plant experiments in any column geometry.The combination of 3-D CFD simulations with droplet population balance models(DPBM)increased the accuracy of the hydrodynamic simulations and gave information about the local droplet size.The high computational costs can be reduced by open source CFD codes when using a flexible mesh generation.First combined simulations using a three way coupled CFD/DPBM/mass-transfer solver pave the way for a safer design of industrial-sized columns,where no correlations are available.
基金Supported by the AiF (Arbeitsgemeinschaft Industrieller Forschungsvereinigungen, "Otto von Guericke" e.V.), the BMWA (Bundesministerium für Wirtschaft und Arbeit) and the DFG (Deutsche Forschungsgemeinschaft)
文摘The technique state to design counter-current extraction columns is based on the performance of pilot plant experiments. The modelling is then either with the equilibrium or dispersion model, whereas in the latter the dispersion coefficient accounts for all hydrodynamic non-idealities. A new approach uses single droplet experiments to obtain the basic laws and functions governing droplet breakage, coalescence, relative velocity, and axial dispersion when using droplet populance balance models （DPBM）. The hydrodynamics simulation results show that the mean Sauter diameter, hold-up, and concentration profiles could be well predicted, which promotes the use of DPBM models for further applications in industrial scale.
基金Supported by the National Natural Science Foundation of China(No.21276279No.21476261)+1 种基金the Fundamental Research Funds for the Central Universities(No.14CX05030ANo.15CX06042A)
文摘Reactive distillation and dividing wall column distillation are two kinds of effective separation technologies,and their integrated configuration,reactive dividing wall column(RDWC),presents attractive advantages.In this study,the rigorous simulation of RDWC for methyl acetate hydrolysis is performed,and sensitivity analysis is conducted to obtain the minimum reboiler duty.Then a comparison is made between the conventional process and RDWC process,and it shows that 20.1% energy savings can be achieved by RDWC process.In addition,the dynamic characteristic of RDWC is studied and an effective control strategy is proposed.The simple PI control scheme with three temperature loops can obtain reasonable control performance and maintain products at desired purities.It is proved that this RDWC process is an energy efficiency alternative with good controllability.
基金supported by the High-level Talents Program of Hebei Province (A 2017002032)
文摘The Sargent dividing wall column can implement four products separation sequences in one column based on Fully Thermally Coupled Distillation Column. The initial design parameters are required for the design optimization or dynamic control of the Sargent dividing wall column, and in order to make the rigorous simulation of the Sargent dividing wall column more conducive to convergence, a ten column model for complex Sargent column is established in this paper,and the shortcut design method of this model is proposed. The internal minimum vapor and liquid flow are obtained by the Underwood equations and the mass balance method and the V-min method. The separation for a 4-component shortcut mixture of pentane, hexane, heptane and octane was considered, while the initial values of design parameters and the ratio of vapor-liquid distribution of each column were calculated by using the shortcut design method of a ten column model. And by comparing the shortcut calculations with rigorous simulation results, the practicality and reliability of shortcut calculations were verified. The reason for energy saving was analyzed based on back-mixing. A virtual heat exchanger is proposed to make the Sargent dividing wall column more energy efficient.
基金financial support from the National High Technology Research and Development Program 863(2011AA05A204)National Natural Science Foundation of China(U1361202)
文摘Isoamylene from the Fischer-Tropsch syncrude can be transformed to valuable fuel oxygenate additives through an equilibrium limited etherification reaction with methanol. A reactive distillation process is established to increase isoamylene conversion. Facing the challenge of improving product purity at the same time, an equilibrium stage model based design methodology is proposed and illustrated step-by-step for converting the Fischer-Tropsch C_5 olefins to tert-amyl methyl ether(TAME) process by using Aspen Plus. Under the guide of the proposed methodology, the design leads to a TAME product purity of higher than 95% and an isoamylene conversion of higher than 90%. The etherification kinetics over Amberlyst 35 is also studied within a temperature range of 60 ℃ to 75 ℃ to shed more light on the feasibility of process development. The methodology provides an effective reactive distillation column design to achieve the target reactant conversion and product purity simultaneously.
文摘This use of biomass-based adsorbent has been explored for the column study of the adsorptive dehydration of water in ethanol-water mixtures. The column study was carried out using enzyme modified corn starch and the breakthrough curve parameters were used to design the packed bed column. The effect of flow rate on the breakthrough curves revealed that adsorption efficiency decreased with increased inflow rate. The empty bed contact time (τ) of the pilot plant packed column was 35.35 min while the breakthrough time is 40.78 min. 66.7% was the fraction of capacity left unused for the pilot plant from the design.
文摘The effects of equipment parameters of batch distillation column on the yield proportion are discussed and analyzed, the relations between maximal yield proportion and the column equipment parameters are correlated, which not only can be used to appraise rationality of the design parameters of the columns being employed and which but also can be used to new batch distillation column design. Under the assistance of the separation difficulty defined in this paper, the minimum number of theoretical plates is determined by the limit loss proportion method given, and further the actual number of theoretical plates and the height for the batch distillation are calculated by using the redundancy coefficient found to complete the whole design of the batch distillation as shown in the computational sample. Research showed that the actual number of theoretical plates and the height of batch distillation column with the column diameter 0.6 m are 17 and 5.1 m in alcohol mixture separation system of the sample proposed. Moreover, the approach can be extended to the design of batch distillation column with a separation system of multi-component liquid mixture after those adjacent components are treated as numerous binary component systems.
基金Supported by:National Natural Science Foundation of China under Grant No.51208175the Fundamental Research Funds for the Central Universities under Grant Nos.2015B17514 and 2016B20514
文摘Four types of seismic design details were tested using 11 transfer column specimens and one comparison specimen of RC under low cyclic reversed loading. Test results show that diagonal cracks control the failure pattern and damage occurs mainly in the RC section with weak shear capacity in the transfer columns. There is a large difference in the bearing capacity and ductility of the transfer columns according to the test results, which indicates that the strengthening effect of diverse structural measures is quite different. The section ratio of I-section-encased steel and the axial compression ratio also have a great influence on the bearing capacity and ductility. Although the bearing capacity of transfer columns with additional longitudinal bars and additional X bars is relatively large, they have poor deformation capacity. Setting more stirrups along the columns is the best structural measure to enhance the seismic performance. The studs on the I-sectionencased steel by welding can help to complete the stress transfer between the steel and concrete, and avoid performance degradation of the two materials due to bonding failure.
文摘This research work investigated comparative studies of expert system design and control of crude oil distillation column (CODC) using artificial neural networks based Monte Carlo (ANNBMC) simulation of random processes and artificial neural networks (ANN) model which were validated using experimental data obtained from functioning crude oil distillation column of Port-Harcourt Refinery, Nigeria by MATLAB computer program. Ninety percent (90%) of the experimental data sets were used for training while ten percent (10%) were used for testing the networks. The maximum relative errors between the experimental and calculated data obtained from the output variables of the neural network for CODC design were 1.98 error % and 0.57 error % when ANN only and ANNBMC were used respectively while their respective values for the maximum relative error were 0.346 error % and 0.124 error % when they were used for the controller prediction. Larger number of iteration steps of below 2500 and 5000 were required to achieve convergence of less than 10-7?for the training error using ANNBMC for both the design of the CODC and controller respectively while less than 400 and 700 iteration steps were needed to achieve convergence of 10-4?using ANN only. The linear regression analysis performed revealed the minimum and maximum prediction accuracies to be 80.65% and 98.79%;and 98.38% and 99.98% when ANN and ANNBMC were used for the CODC design respectively. Also, the minimum and maximum prediction accuracies were 92.83% and 99.34%;and 98.89% and 99.71% when ANN and ANNBMC were used for the CODC controller respectively as both methodologies have excellent predictions. Hence, artificial neural networks based Monte Carlo simulation is an effective and better tool for the design and control of crude oil distillation column.
