An alternative for the collection of small particles in cyclones: Experimental analysis and CFD modeling

Classification of Ultrafine Particles Using a Novel 3D-Printed Hydrocyclone with an Arc Inlet: Experiment and CFD Modeling

Ultrafine particle classification can be realized using hydrocyclones with novel structures to overcome the limitations of conventional hydrocyclones with tangential inlets or cone structures. Herein, the hydrocyclones with different inlet structures and cone angles were investigated for classifying ultrafine particles. Computational fluid dynamics (CFD) simulations were performed using the Eulerian-Eulerian method, and ultrafine MnO₂ powder was used as a case study. The simulation results show a fine particle (≤5 μm) removal efficiency of 0.89 and coarse particle (>5 μm) recovery efficiency of 0.99 for a hydrocyclone design combining an arc inlet and a 30° cone angle under a solid concentration of 2.5 wt %. Dynamic analysis indicated that the novel arc inlet provided a preclassification effect to reduce the misplacement of fine/coarse particles, which cannot be provided by conventional tangential or involute inlets. Furthermore, the proposed design afforded comprehensive improvement in the flow field by regulating the residence time and radial acceleration. Subsequently, a novel hydrocyclone with an arc inlet and 30° cone angle was manufactured using the three-dimensional (3D) printing technology. Experiments were conducted for classifying ultrafine MnO₂ particles using the novel 3D-printed hydrocyclone and conventional hydrocyclone. The results demonstrate that the classification performance of the 3D-printed hydrocyclone was superior to that of the conventional one, in particular, the removal efficiency of fine particles from 0.719 to 0.930 using a 10 wt % feed slurry.

Engineering Advances in Spray Drying for Pharmaceuticals

Spray drying is a versatile technology that has been applied widely in the chemical, food, and, most recently, pharmaceutical industries. This review focuses on engineering advances and the most significant applications of spray drying for pharmaceuticals. An in-depth view of the process and its use is provided for amorphous solid dispersions, a major, growing drug-delivery approach. Enhanced understanding of the relationship of spray-drying process parameters to final product quality attributes has made robust product development possible to address a wide range of pharmaceutical problem statements. Formulation and process optimization have leveraged the knowledge gained as the technology has matured, enabling improved process development from early feasibility screening through commercial applications. Spray drying's use for approved small-molecule oral products is highlighted, as are emerging applications specific to delivery of biologics and non-oral delivery of dry powders. Based on the changing landscape of the industry, significant future opportunities exist for pharmaceutical spray drying.

Effect of External Cyclone Diameter on Performance of a Two-Stage Cyclone Separator

As a widely used separation device, a cyclone separator is especially important to improve its separation efficiency. In this paper, a new two-stage cyclone separator is designed and modeled by the Reynolds stress model. Under the premise of determining the diameter of the second-stage cyclone (D), the effects of five first-stage cyclone diameters (Du) on the performance of the two-stage cyclone are simulated. The performance of the single-stage cyclone separator is also obtained. The results show that Du has significant effects on the internal pressure field, flow field, and vortex core of the two-stage cyclone. Compared with the single-stage cyclone separator, the separation efficiency of the two-stage cyclone separator is significantly improved. When Du = 6D, the separation efficiency is improved by 15.5% compared with that of the single-stage cyclone. In addition, the two-stage cyclone separator can effectively reduce the Euler number.

Effect of Inlet Air Volumetric Flow Rate on the Performance of a Two-Stage Cyclone Separator

It is very important to improve the cyclone separator separation efficiency for fine particles. On the basis of the Reynolds stress model (RSM), a new two-stage cyclone separation device is modeled and the model is simulated under six kinds of air volumetric flow rate conditions. The two-stage cyclone separator was then tested in the laboratory and the experimental data were compared with the simulation data. The results show that the RSM model can predict the performance of the two-stage cyclone separation device with high accuracy. Increasing of the air volumetric flow rate can not only improve the separation efficiency of the two-stage cyclone separator, but also effectively change the classification range. Because of the centrifugal force, even if the pressure drop is low, the 1st-cyclone can completely separate particles above 5.0 μm. When the air volumetric flow rate is more than 290 m³/h, the 2nd-cyclone can effectively separate the particles below 2.0 μm. The study also confirmed the nonlinear relationship between the pressure drop and the cut-off particle size and the maximum particle size. When the pressure drop exceeds a certain value, there is no longer any effect on the cut-off particle size and the maximum particle size.

A numerical study on the behavior of coastal waste particles in a wind-power sorting system for renewable fuel production

In this study, a Computational Fluid Dynamics (CFD) to analyze the coastal waste particles in a wind-power sorting system is applied to produce renewable fuel using commercial CFD package (ANSYS-CFX code). The numerical methodology results predicted various coastal waste shredded inside the sorting machine. Furthermore, to identify the effect of working conditions on separation characteristics, a parametric study is performed. These study findings will offer appropriate a wind-power sorting conditions according to the purpose of using coastal waste. Under basic conditions, the characteristics of coastal waste particle behavior and the sorting of waste particles were analyzed, and the behavioral changes of diverse particles were identified by changing the airflow rate to improve the sorting performance. As a result, an appropriate airflow rate, Q_air = 85 m³/min, at which the change in the airflow rate can simultaneously meet the conditions for both the recovery of the combustibles and the removal of the incombustibles, was selected with the selection efficiency rate was 92%, and the combustibles content was 99%. Based on the results of the analysis, the particle characteristics of sorting were identified to reduce and recycle the coastal waste.