Assessment of the Mixing of Polydisperse Solid Particles in the Rotary Drum and Slant Cone Mixers Using Discrete Element Method

In spite of wide applications of powders in industry, there is a lack of sufficient knowledge regarding the mixing of poly-disperse particles in rotary drum and slant cone mixers. The main objective of this study was to explore the mixing quality of mono-disperse, bi-disperse, tri-disperse, and poly-disperse particles inside rotary drum and slant cone mixers as a function of the drum speed, particle size, agitator speed, and the initial loading method through the discrete element method (DEM). To achieve this objective, experimental work and simulations were carried out. DEM results were validated using experimental data obtained from both sampling and image analysis techniques. DEM simulation results were in good agreement with the experimentally determined data, both qualitatively and quantitatively. Three major loading methods were defined: side-side, top-bottom, and back-front. Also, the mixing metric was utilized to measure the mixing quality. For bi-disperse particles inside the slant cone mixer, the mixing index increased to a maximum and decreased slightly before reaching a plateau at the drum speed of 15 rpm with different loading methods as a direct result of the segregation of particles of different sizes. The same behavior was observed in the rotary drum for bi-disperse, tri-disperse, and poly-disperse particles. The effect of agitator speed on the mixing performance for bi-disperse particles inside the slant cone mixer was also investigated. The addition of the agitator increased the mixing quality and reduced the segregation of particles with different sizes. The best mixing qualities for the tri-disperse and poly-disperse particles inside the rotary drum were recorded for the top-bottom smaller-to-larger loading method. For the slant cone mixer, highest mixing indices for tri-disperse and poly-disperse particles with the top-bottom smaller-to-larger loading method were obtained at drum speeds of 15 and 55 rpm, respectively. The impact of segregation for both mixers was reduced by introducing additional intermediate size particles.

Assessment of the Mixing of Polydisperse Solid Particles in the Rotary Drum and Slant Cone Mixers Using Discrete Element Method

In spite of wide applications of powders in industry, there is a lack of sufficient knowledge regarding the mixing of poly-disperse particles in rotary drum and slant cone mixers. The main objective of this study was to explore the mixing quality of mono-disperse, bi-disperse, tri-disperse, and poly-disperse particles inside rotary drum and slant cone mixers as a function of the drum speed, particle size, agitator speed, and the initial loading method through the discrete element method (DEM). To achieve this objective, experimental work and simulations were carried out. DEM results were validated using experimental data obtained from both sampling and image analysis techniques. DEM simulation results were in good agreement with the experimentally determined data, both qualitatively and quantitatively. Three major loading methods were defined: side-side, top-bottom, and back-front. Also, the mixing metric was utilized to measure the mixing quality. For bi-disperse particles inside the slant cone mixer, the mixing index increased to a maximum and decreased slightly before reaching a plateau at the drum speed of 15 rpm with different loading methods as a direct result of the segregation of particles of different sizes. The same behavior was observed in the rotary drum for bi-disperse, tri-disperse, and poly-disperse particles. The effect of agitator speed on the mixing performance for bi-disperse particles inside the slant cone mixer was also investigated. The addition of the agitator increased the mixing quality and reduced the segregation of particles with different sizes. The best mixing qualities for the tri-disperse and poly-disperse particles inside the rotary drum were recorded for the top-bottom smaller-to-larger loading method. For the slant cone mixer, highest mixing indices for tri-disperse and poly-disperse particles with the top-bottom smaller-to-larger loading method were obtained at drum speeds of 15 and 55 rpm, respectively. The impact of segregation for both mixers was reduced by introducing additional intermediate size particles.

Evaluation of the mixing quality of high-viscosity yield stress fluids in a tubular reactor

In this study, the mixing quality of high-viscosity yield stress fluid (Carbopol aqueous solution) under laminar and turbulent flow regimes was evaluated through a numerical experimental study. A three-dimensional computational fluid dynamics large-eddy simulation (CFD-LES) model was employed to capture large-scale vortex structures. The proposed CFD model was validated by the experimental data in terms of mean velocity profiles and velocity-time history. Thereafter, the CFD model was applied to simulate the residence time distribution using the tracking technique: tracer pulse method and step method. In addition, the non-ideal flow phenomena caused by molecular diffusion and eddy diffusion were evaluated. The effects of the rheological properties on the mixing performance were also investigated. The presented results can provide useful guidance to enhance mass transfer in reactors with high-viscosity fluids.

Mixing Assessment of Non-Cohesive Mono-disperse and Bi-disperse Particles in a Paddle Mixer – Experiments and Discrete Element Method (DEM) Application

The objective of this study was to assess the mixing performance of a horizontal paddle blender for mono-disperse and bi-disperse particles. The assessment was performed through the application of the Discrete Element Method (DEM) simulations, experiments, and Analysis of Variance (ANOVA). EDEM 2.7 commercial software was utilized for the mono-disperse simulations while LIGGGHTS(R)-PUBLIC 3.3.1, an open source software, was used for the bi-disperse simulations. DEM models were validated with experimental data. Simulations were performed to explore the effect of impeller rotational speed, vessel fill level, particle number composition, and particle loading arrangement on mixing quality defined by the Relative Standard Deviation (RSD) index. The flow pattern and mixing mechanisms were examined through granular temperature, particle diffusivity, and Peclet number. The impeller rotational speed was the most influential parameter on the mixing performance of mono-disperse particles. The particle number composition was the dominating parameter on the mixing quality of bi-disperse particles

Mixing Assessment of Non-Cohesive Mono-disperse and Bi-disperse Particles in a Paddle Mixer – Experiments and Discrete Element Method (DEM) Application

The objective of this study was to assess the mixing performance of a horizontal paddle blender for mono-disperse and bi-disperse particles. The assessment was performed through the application of the Discrete Element Method (DEM) simulations, experiments, and Analysis of Variance (ANOVA). EDEM 2.7 commercial software was utilized for the mono-disperse simulations while LIGGGHTS(R)-PUBLIC 3.3.1, an open source software, was used for the bi-disperse simulations. DEM models were validated with experimental data. Simulations were performed to explore the effect of impeller rotational speed, vessel fill level, particle number composition, and particle loading arrangement on mixing quality defined by the Relative Standard Deviation (RSD) index. The flow pattern and mixing mechanisms were examined through granular temperature, particle diffusivity, and Peclet number. The impeller rotational speed was the most influential parameter on the mixing performance of mono-disperse particles. The particle number composition was the dominating parameter on the mixing quality of bi-disperse particles

A Novel Approach For Analyzing Mixing Quality In Solid-Liquid Stirred Tanks Via Coupled Computational Fluid Dynamics - Discrete Element Method And Electrical Resistance Tomography

The mixing quality of a solid-liquid stirred tank operating in the turbulent regime was investigated, numerically and to an extent experimentally. Simulations were performed by coupling Computational Fluid Dynamics (CFD) and the Discrete Element Method (DEM). The results were evaluated against experimental data obtained using Electrical Resistance Tomography (ERT). This facilitated a novel and more rigorous assessment of CFD-DEM coupling – i.e. based on the spatial distribution of particle concentrations. Furthermore, a new mixing index definition was developed to quantify suspension quality to work in tandem with existing dispersion mixing indexes. This provides a more complete interpretation of mixing quality. In this work, it was found that the model underestimated suspension and dispersion due to model limitations associated with mesh size and fluid-particle interaction models. Furthermore, the predicted mixing quality was sensitive to changes in the drag model, including other fluid-particle interaction forces in simulations, and variations in certain particle properties

A Novel Approach For Analyzing Mixing Quality In Solid-Liquid Stirred Tanks Via Coupled Computational Fluid Dynamics - Discrete Element Method And Electrical Resistance Tomography

The mixing quality of a solid-liquid stirred tank operating in the turbulent regime was investigated, numerically and to an extent experimentally. Simulations were performed by coupling Computational Fluid Dynamics (CFD) and the Discrete Element Method (DEM). The results were evaluated against experimental data obtained using Electrical Resistance Tomography (ERT). This facilitated a novel and more rigorous assessment of CFD-DEM coupling – i.e. based on the spatial distribution of particle concentrations. Furthermore, a new mixing index definition was developed to quantify suspension quality to work in tandem with existing dispersion mixing indexes. This provides a more complete interpretation of mixing quality. In this work, it was found that the model underestimated suspension and dispersion due to model limitations associated with mesh size and fluid-particle interaction models. Furthermore, the predicted mixing quality was sensitive to changes in the drag model, including other fluid-particle interaction forces in simulations, and variations in certain particle properties