Development of a CFD-DEM Model for a 1 MW_th Chemical Looping Gasification Pilot Plant Using Biogenic Residues as...

Area of Science:

• Chemical Engineering
• Thermodynamics
• Fluidized Bed Reactors

Background:

• Chemical looping gasification (CLG) offers a cost-effective route to nitrogen-free syngas via in situ air separation.
• Existing CLG models are predominantly lab-scale or 1D, limiting application to larger industrial processes.

Purpose of the Study:

• To develop and validate a 3D Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) model for a 1 MWth fuel reactor in CLG.
• To simulate the conversion of solid biomass feedstocks, including woody biomass and wheat straw.

Main Methods:

• A coarse-grained CFD-DEM approach was employed with a simplified reaction network to manage computational demands.
• The Eulerian-Eulerian Multiphase (EMMS) drag model was utilized for hydrodynamics.
• Simulations were validated against experimental data from a 1 MWth CLG reactor.

Main Results:

• The model accurately predicted pressure profiles (mean error <10%) and achieved good agreement for carbon conversion and oxygen carrier oxidation (mean deviation <5%).
• Gas composition predictions showed reasonable accuracy (mean error <8%).
• Discrepancies in gas composition and temperature profiles suggest areas for model refinement, particularly in the pyrolysis step.

Conclusions:

• The developed 3D CFD-DEM model provides a reliable tool for simulating large-scale CLG processes.
• The model demonstrates good predictive capability for key performance indicators, supporting the design and optimization of CLG reactors.
• Further refinement of the pyrolysis sub-model is recommended for enhanced accuracy.