Spouted Beds are a novel innovation that came about in the early 1950s as a creative way to get around the problems with regular wheat crushers. Mathur and Gishler were made to fix the problem of grain damage caused by traditional drying methods that didn’t move particles around enough. The most important thing about SBs is that the particles move quickly inside the reactors. Today, SBs are very important in many industrial processes, such as drying grains, coating them, heterogeneous catalysis, gasification, combustion, and the pyrolysis of trash. A typical SB works by letting fluid into the system through a center hole. This makes three separate areas: the spout, the fountain, and the annulus. The current spouted Bed CFD study has gained credit from several reference papers as listed below:

• Reference [1]: Moliner, Cristina, et al. “CFD simulation of a spouted bed: Comparison between the Discrete Element Method (DEM) and the Two Fluid Model (TFM).” Chemical Engineering Journal377 (2019): 120466.
• [2]: Moliner, Cristina, et al. “Sensitivity analysis and validation of a Two Fluid Method (TFM) model for a spouted bed.” Chemical Engineering Science207 (2019): 39-53.

Figure 1: Schematic representation of the flow regimes in spouted bed CFD simulation [1]

Simulation Process

In all simulations, the experimental setup mentioned in Zhao et al. (2008) was used to make a model of the real testing setup. A simplified 3D model designed by the Design Modeler and its measurements can be seen in Fig.2. Then, a structured grid with 7500 discritezied the domain. As the title of the project suggests, Two Fluid Method (TFM) is employed. Thus, a Eulerian-Eulerian approach is adopted regarding a granular solid phase in the spouted bed. This is done by Eulerian multiphase model in ANSYS Fluent, supporting by appropriate granular properties and drag, lift,etc parameters and unsteady (transient) solver .

Figure 2: Schematic and structured grid over the spouted bed CFD simulation [1]

Post-processing

The Two Fluid Method (TFM) simulation data for the spouted bed at 5.6279 seconds gives us useful information about how the particles’ speeds are spread out in the system. The contour shows very well the three separate parts of a spouted bed: the spout, the fountain, and the annulus. The spout, which can be seen as a narrow, high-velocity area extending from the bottom inlet, has the fastest particle speeds, which are shown by light blue to red colors ranging from 1.53 to 2.61 m/s. This zone of high speed successfully lifts particles from the bed’s bottom, making the central spout. Higher-speed particles (green to yellow colors) moving at speeds between 1.23 and 1.84 m/s make the fountain area at the top of the bed easy to see. This area shows how the particles on the bed’s surface are spread out in a circular pattern.

More than half of the bed volume is made up of the annulus area, which has slower particle speeds, mostly between 0 and 0.46 m/s (dark blue colors). The particles in the annulus moving slowly downward are very important for keeping the cycle motion going in the spouted bed. Two even areas with slightly faster flow (light blue) can be seen on either side of the spout near the bed’s bottom. This is an interesting trait. With speeds between 0.77 and 0.92 m/s, these areas are probably where particles are being drawn into the spout, which adds to the general flow pattern. The ability to clearly see these different speed zones shows that the TFM simulation accurately models the complicated hydrodynamics of the spouted bed.