Accuracy improvement of CFD modeling of a hydraulics with wood pellet combustion operating in a full-loop circulating fluidized bed combustor (CFBC)

• Published in: Biomass conversion and biorefinery Vol. 14; no. 6; pp. 7807 - 7833
• Main Authors: Park, Sang Shin, Moon, Ji-Hong, Yoon, Sang-Hee, Baek, Geon-Uk, Jo, Sungho, Park, Sung-Jin, Kim, Jae-Young, Yoon, Sang-Jun, Lee, Jae-Goo, Ra, Ho Won, Yoon, Sung-Min, Mun, Tae-Young
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-03-2024; Springer Nature B.V
• Subjects: Accuracy; Biotechnology; Carbon dioxide; Combustion chambers; Computational fluid dynamics; Energy; Fluid flow; Fluidized bed combustion; Fluidized beds; Hydraulics; Mathematical models; Original Article; Parameters; Particle size; Particle size distribution; Pellets; Renewable and Green Energy; Sand; Sulfur dioxide; Sand particle size; Circulated fluidized bed combustor (CFBC); Combustion; Chemical reaction; Wood pellet; Particle behavior
• ISSN: 2190-6815; 2190-6823
• DOI: 10.1007/s13399-022-03108-6

Three-dimensional computational fluid dynamics (CFD) modeling of the hydrodynamic characteristics for the various sand particle sizes (10 μm, 250 μm, 482 μm, 750 μm, 1000 μm, and the actual particle size distribution (PSD)) in a 0.1 MW
th
pilot-scale full-loop circulating fluidized bed combustor (CFBC) was numerically investigated with a commercial CFD code, ANSYS FLUENT. Those were clearly validated with actual CFBC operating data. As the result, the sand particle size of the actual PSD was in good agreement. In order to accurately simulate wood pellet combustion, kinetic parameters for activation energy (
E
a
) and pre-exponential factor (
A
) for wood pellet decomposition and char combustion were obtained from lab-scale TGA experiments with wood pellet sample actually used for CFBC operation. The CFD modeling on wood pellet combustion were conducted with the selected sand particle size of actual PSD with improved char combustion model using the user-defined function (UDF) reflected kinetic parameters. The CFD modeling results were carefully compared with actual CFBC operating results. Therefore, our CFD simulation results for the concentrations of gas species (N
2
, CO
2
, O
2
, SO
2
, CO, NO, and N
2
O) at the gas exit in the cyclone were also in good agreement with the actual CFBC operating data. The accuracy improvements were increased from 1.9 times to 2.5 times due to our improved char combustion model using the UDF.