The study of the influence of slug density on the mixing performance in the reactor vessel, using PLIF experiment and FLUENT simulation

2021 ◽  
Vol 131 ◽  
pp. 103558
Author(s):  
Abdelgadir Eltayeb ◽  
Sichao Tan ◽  
Ayodeji A. Ala ◽  
Qi Zhang
Processes ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 464
Author(s):  
Xingren Jiang ◽  
Ning Yang ◽  
Rijie Wang

Continuous manufacturing has received increasing interest because of the advantages of intrinsic safety and enhanced mass transfer in the pharmaceutical industry. However, the difficulty for scale-up has limited the application of continuous manufacturing for a long time. Recently, the tubular flow reactor equipped with the Kenics static mixer appears to be a solution for the continuous process scale-up. Although many influence factors on the mixing performance in the Kenics static mixer have been investigated, little research has been carried out on the aspect ratio. In this study, we used the coefficient of variation as the mixing evaluation index to investigate the effect of the aspect ratio (0.2–2) on the Kenics static mixer’s mixing performance. The results indicate that a low aspect ratio helps obtain a shorter mixing time and mixer length. This study suggests that adjusting the aspect ratio of the Kenics static mixer can be a new strategy for the scale-up of a continuous process in the pharmaceutical industry.


2021 ◽  
Vol 13 (8) ◽  
pp. 4255
Author(s):  
Mingmin Kong ◽  
Shuaiming Feng ◽  
Qi Xia ◽  
Chen Chen ◽  
Zhouxin Pan ◽  
...  

Hydrogen is of great significance for replacing fossil fuels and reducing carbon dioxide emissions. The application of hydrogen mixing with natural gas in gas network transportation not only improves the utilization rate of hydrogen energy, but also reduces the cost of large-scale updating household or commercial appliance. This paper investigates the necessity of a gas mixing device for adding hydrogen to existing natural gas pipelines in the industrial gas network. A three-dimensional helical static mixer model is developed to simulate the mixing behavior of the gas mixture. In addition, the model is validated with experimental results. Parametric studies are performed to investigate the effect of mixer on the mixing performance including the coefficient of variation (COV) and pressure loss. The research results show that, based on the, the optimum number of mixing units is three. The arrangement of the torsion angle of the mixing unit has a greater impact on the COV. When the torsion angle θ = 120°, the COV has a minimum value of 0.66%, and when the torsion angle θ = 60°, the COV has a maximum value of 8.54%. The distance of the mixing unit has little effect on the pressure loss of the mixed gas but has a greater impact on the COV. Consecutive arrangement of the mixing units (Case A) is the best solution. Increasing the distance of the mixing unit is not effective for the gas mixing effect. Last but not least, the gas mixer is optimized to improve the mixing performance.


Processes ◽  
2020 ◽  
Vol 8 (10) ◽  
pp. 1236
Author(s):  
Hamid Mortazavi ◽  
Leila Pakzad

Oscillatory baffled reactors (OBRs) have attracted much attention from researchers and industries alike due to their proven advantages in mixing, scale-up, and cost-effectiveness over conventional stirred tank reactors (STRs). This study quantitatively investigated how different mixing indices describe the mixing performance of a moving baffle OBR using computational fluid dynamics (CFD). In addition, the hydrodynamic behavior of the reactor was studied, considering parameters such as the Q-criterion, shear strain rate, and velocity vector. A modification of the Q-criterion showed advantages over the original Q-criterion in determination of the vortices’ locations. The dynamic mesh tool was utilized to simulate the moving baffles through ANSYS/Fluent. The mixing indices studied were the velocity ratio, turbulent length scale, turbulent time scale, mixing time, and axial dispersion coefficient. We found that the oscillation amplitude had the most significant impact on these indices. In contrast, the oscillatory Reynolds number did not necessarily describe the mixing intensity of a system. Of the tested indices, the axial dispersion coefficient showed advantages over the other indices for quantifying the mixing performance of a moving baffle OBR.


Author(s):  
Hao Qian ◽  
Li Yiguo ◽  
Peng Dan ◽  
Wu Xiaobo ◽  
Lu Jin ◽  
...  

In order to solve the problem that the current unloading operation will destroy the sealing performance of Miniature Neutron Source Reactor (MNSR) reactor vessel and the tightness can’t be restored, and to meet the application requirements that the original reactor vessel will be reloaded and operated after MNSR LEU conversion, the new unloading device is designed, which can be used without separation of reactor vessel. There has only one fuel assembly in MNSR. When the fuel assembly are unload for MNSR LEU conversion, the cover plate of the pool is removed, the cadmium string is put in, and the neutron detector is placed at first. After removing the drive mechanism and the control rod, and opening the small cover plate at the top of reactor vessel, the fuel assembly can be grabbed and unloaded by unloading tool only through the opening of the small top cover plate. The MNSR spent fuel has very high radioactivity. The auxiliary mechanical device can be used with unloading tools to realize operation in a long distance by lifting and level motion, which is convenient to shield and can reduce the works’ irradiation dose level effectively. Through calculation and analysis, the results show that the structure strength of unloading device is much larger than the actual load to ensure operation safety and reliability. The unloading device is easy to process and operate, and can be used in the practical operation of MNSR LEU conversion or decommissioning at home and abroad to simplify the operation steps and improve the working efficiency.


2017 ◽  
Vol 2017 ◽  
pp. 1-7
Author(s):  
Mazhyn K. Skakov ◽  
Nurzhan Ye. Mukhamedov ◽  
Alexander D. Vurim ◽  
Ilya I. Deryavko

For the first time the paper determines thermophysical properties (specific heat capacity, thermal diffusivity, and heat conductivity) of the full-scale corium of the fast energy nuclear reactor within the temperature range from ~30°С to ~400°С. Obtained data are to be used in temperature fields calculations during modeling the processes of corium melt retention inside of the fast reactor vessel.


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