A new configuration of coalescence-dispersed pulsed-sieve-plate extraction column (CDPSEC) was developed, and the mass transfer and axial mixing characteristics were evaluated with the two-point dynamic method.The inf...A new configuration of coalescence-dispersed pulsed-sieve-plate extraction column (CDPSEC) was developed, and the mass transfer and axial mixing characteristics were evaluated with the two-point dynamic method.The influence of operation conditions was discussed with experimental results, showing that the mass transfer performance of CDPSEC mainly depends on the energy input and the holdup of dispersed phase. Higher energy input results in higher holdup of the dispersed phase, the axial mixing of the continuous phase is suppressed, and the true height of mass transfer unit decreases markedly. On the other hand, higher energy input leads to more serious forward mixing of the dispersed phase, so the energy input should be limited. Accordingly the operation conditions were divided into two regions, and empirical correlations for predicting the mass transfer and axial mixing characteristics in different regions with a satisfactory accuracy were suggested.展开更多
Liquid phase axial mixing was measured with the tracer technique in a packed column with inner diameter of 0.15m, in which the structured packing, Mellapak 350Y, was installed. Tap water as the liquid phase flowed dow...Liquid phase axial mixing was measured with the tracer technique in a packed column with inner diameter of 0.15m, in which the structured packing, Mellapak 350Y, was installed. Tap water as the liquid phase flowed down through the column and stagnant gas was at elevated pressure ranging from atmospheric to 2.0MPa. The model parameters of Bo and 9 were estimated with the least square method in the time domain. As liquid flow rate was increased, the liquid axial mixing decreased. Under our experimental conditions, the effect of pressure on Bo number on single liquid phase was negligible, and eddy diffusion was believed to be the primary cause of axial mixing in liquid phase.展开更多
To evaluate the influence of gas and liquid axial mixings on the separation efficiency of packed column, an approximate mathematical solution of HETP (equivalent height to a theoretical plate) under continuous operati...To evaluate the influence of gas and liquid axial mixings on the separation efficiency of packed column, an approximate mathematical solution of HETP (equivalent height to a theoretical plate) under continuous operation has been proposed based on the mixing pool model. The mass transfer and hydrodynamic data of structured packing, Mellapak 350Y, obtained in a high pressure tower have been used to test the validity of the proposed model. Compared with the SRP model and the Gualito model, it is found that for high pressure distillation process the present mathematical prediction shows a mean relative error of about 10% to the experimental data,the accuracy of which is the same as that by the Gualito model but better than that by the SRP model.展开更多
The mixing performance of a multi-bladed tote blender is investigated using a graphics processing unit-based discrete element method program.The positioning,dimensions,and applicability of the baffles are systematical...The mixing performance of a multi-bladed tote blender is investigated using a graphics processing unit-based discrete element method program.The positioning,dimensions,and applicability of the baffles are systematically studied according to the axial mixing efficiency.The results indicate that the novel inclined multi-bladed baffles can break the symmetrical axial granular flow and introduce a more efficient convective flow into the granular mixing in the axial direction of the tote blender.Owing to the joint effects of convective mixing and asymmetrical granular flow,the axial mixing efficiency is increased by a factor of nearly 20.More importantly,the novel baffle placement approach exhibits excellent applicability to different operating conditions,particle shapes,and blender sizes.Additionally,the inclined baffles can prevent the segregation caused by shape discrepancies and improve the mixing homogeneity in the steady state.The novel baffle design is promising for applications in more complex industrial blenders for achieving a high axial mixing efficiency.展开更多
Conical spouted beds operating with high-density particles(ρp>2500 kg/m^(3))have recently gained attention because of their potential use as nuclear fuel coaters for next-generation nuclear reactors.In the literat...Conical spouted beds operating with high-density particles(ρp>2500 kg/m^(3))have recently gained attention because of their potential use as nuclear fuel coaters for next-generation nuclear reactors.In the literature,the number of axial gas mixing studies in conical and conical-cylindrical spouted beds is very limited and all axial mixing studies were carried out with relatively light particles(ρp≤2500 kg/m^(3)).Therefore,the objective of this study was to generate experimental data that can be used to explain the gas axial mixing behavior in conical spouted beds operating with both low-and high-density particles.Experiments were conducted in two(γ=30°,60°)conical spouted beds with three different types of particles:zirconia(ρp=6050 kg/m^(3)),zirconia toughened alumina(ρp=3700 kg/m^(3))and glass beads(ρp=2460 kg/m^(3)).In order to be able to compare experimental data obtained at different conditions,a 1-D convection-diffusion gas mixing model originally developed by San Joséet al.(1995)was implemented to determine the axial dispersion coefficients.The results show that the axial dispersion coefficients range between m^(2)/s and m^(2)/s,increase with superficial gas velocity and are higher than the corresponding dispersion coefficients of fixed beds,lower than the dispersion coefficients of fluidized beds and in the same range with the cylindrical spouted beds reported in the literature.The corresponding Peclet numbers were in the range of 0.6–7.8 for all operating conditions and slightly higher Peclet numbers were obtained with glass beads indicating the relative importance of gas convective transport over gas dispersion for light particles compared to heavy particles.展开更多
文摘A new configuration of coalescence-dispersed pulsed-sieve-plate extraction column (CDPSEC) was developed, and the mass transfer and axial mixing characteristics were evaluated with the two-point dynamic method.The influence of operation conditions was discussed with experimental results, showing that the mass transfer performance of CDPSEC mainly depends on the energy input and the holdup of dispersed phase. Higher energy input results in higher holdup of the dispersed phase, the axial mixing of the continuous phase is suppressed, and the true height of mass transfer unit decreases markedly. On the other hand, higher energy input leads to more serious forward mixing of the dispersed phase, so the energy input should be limited. Accordingly the operation conditions were divided into two regions, and empirical correlations for predicting the mass transfer and axial mixing characteristics in different regions with a satisfactory accuracy were suggested.
基金Supported by the National Natural Science Foundation of China (No. 20136010).
文摘Liquid phase axial mixing was measured with the tracer technique in a packed column with inner diameter of 0.15m, in which the structured packing, Mellapak 350Y, was installed. Tap water as the liquid phase flowed down through the column and stagnant gas was at elevated pressure ranging from atmospheric to 2.0MPa. The model parameters of Bo and 9 were estimated with the least square method in the time domain. As liquid flow rate was increased, the liquid axial mixing decreased. Under our experimental conditions, the effect of pressure on Bo number on single liquid phase was negligible, and eddy diffusion was believed to be the primary cause of axial mixing in liquid phase.
文摘To evaluate the influence of gas and liquid axial mixings on the separation efficiency of packed column, an approximate mathematical solution of HETP (equivalent height to a theoretical plate) under continuous operation has been proposed based on the mixing pool model. The mass transfer and hydrodynamic data of structured packing, Mellapak 350Y, obtained in a high pressure tower have been used to test the validity of the proposed model. Compared with the SRP model and the Gualito model, it is found that for high pressure distillation process the present mathematical prediction shows a mean relative error of about 10% to the experimental data,the accuracy of which is the same as that by the Gualito model but better than that by the SRP model.
基金This work was supported by the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20190892)the Scientific Research Starting Foundation of Jjining University,Shandong Province,China(Grant No.2019BSZX04)Binzhou University,Shandong Province,China(Grant No.2018Y25].
文摘The mixing performance of a multi-bladed tote blender is investigated using a graphics processing unit-based discrete element method program.The positioning,dimensions,and applicability of the baffles are systematically studied according to the axial mixing efficiency.The results indicate that the novel inclined multi-bladed baffles can break the symmetrical axial granular flow and introduce a more efficient convective flow into the granular mixing in the axial direction of the tote blender.Owing to the joint effects of convective mixing and asymmetrical granular flow,the axial mixing efficiency is increased by a factor of nearly 20.More importantly,the novel baffle placement approach exhibits excellent applicability to different operating conditions,particle shapes,and blender sizes.Additionally,the inclined baffles can prevent the segregation caused by shape discrepancies and improve the mixing homogeneity in the steady state.The novel baffle design is promising for applications in more complex industrial blenders for achieving a high axial mixing efficiency.
基金This work was carried out with the financial support of the Scientific and Technological Research Council of Turkey(Project No:MAG 115M392)。
文摘Conical spouted beds operating with high-density particles(ρp>2500 kg/m^(3))have recently gained attention because of their potential use as nuclear fuel coaters for next-generation nuclear reactors.In the literature,the number of axial gas mixing studies in conical and conical-cylindrical spouted beds is very limited and all axial mixing studies were carried out with relatively light particles(ρp≤2500 kg/m^(3)).Therefore,the objective of this study was to generate experimental data that can be used to explain the gas axial mixing behavior in conical spouted beds operating with both low-and high-density particles.Experiments were conducted in two(γ=30°,60°)conical spouted beds with three different types of particles:zirconia(ρp=6050 kg/m^(3)),zirconia toughened alumina(ρp=3700 kg/m^(3))and glass beads(ρp=2460 kg/m^(3)).In order to be able to compare experimental data obtained at different conditions,a 1-D convection-diffusion gas mixing model originally developed by San Joséet al.(1995)was implemented to determine the axial dispersion coefficients.The results show that the axial dispersion coefficients range between m^(2)/s and m^(2)/s,increase with superficial gas velocity and are higher than the corresponding dispersion coefficients of fixed beds,lower than the dispersion coefficients of fluidized beds and in the same range with the cylindrical spouted beds reported in the literature.The corresponding Peclet numbers were in the range of 0.6–7.8 for all operating conditions and slightly higher Peclet numbers were obtained with glass beads indicating the relative importance of gas convective transport over gas dispersion for light particles compared to heavy particles.
