Challenges And Solutions For Modeling Group A Particles.pdf

Small Scale Studies for Geldart Group A Particles

This paper presents mini-C2U experimental and MFIX-TFM/DEM simulations focusing on the hydrodynamics and CO2 capture performance of a 10-cm bubbling bed filled with NETL 32D sorbents (diameter: 100 µm, density: 480 kg/m³, Umf: 0.0023 m/s).

Challenges in Modeling Group A Particles:

CFD Modeling: Predicting the behavior of these particles in CFD presents significant challenges due to their large surface area and good fluidization properties.
TFM Over-Prediction: Previous studies have shown TFM often overpredicts bed expansion for Group A particles, highlighting limitations in considering cohesive forces and particle size distribution (PSD).
DEM Costliness: Direct simulation using DEM is computationally expensive due to the large number of particles involved in most industrial applications.
Lack of Validation Data: There's a dearth of small-scale experiments with manageable particle counts and detailed measurements for validating DEM simulations.

Mini-C2U Setup and Findings:

An experimental setup was used to measure bed height, flow velocity, and other parameters under different conditions.
MFIX-TFM simulations incorporated kinetic granular theory, algebraic granular temperature, and Schaeffer friction model with a grid size of 4 mm (40 Dp).
Key observations:
Homogeneous expansion vs. vigorous bubbling was observed.
* The simulation overpredicted bed height from 24 cm to 19 cm, consistent with literature findings for Group A particles.

Conclusion:

The study emphasizes the need for improved heterogeneous drag models tailored for Group A particles, bridging the gap between experimental data and CFD simulations for better process design and optimization in CO2 capture technologies like Fluidized Bed Reactors (FBRs).