Experiments support simulations by the NEPTUNE_CFD code in an Upflow Bubbling Fluidized Bed reactor

Florian Sabatier (1) , Renaud Ansart (1) , Zhang Huili (2) , Jan Baeyens (2) , Olivier Simonin (3)

1 LGC - Laboratoire de Génie Chimique
2 Beijing University of Chemical Technology
3 IMFT - Institut de mécanique des fluides de Toulouse

Long tubes with small internal diameter find increasing applications in indirect concentrated solar receivers using an Upflow Bubbling Fluidized Bed of Geldart-A powders as heat carrier. Although successfully demonstrated for tubes of 0.5 to 1 m length, longer tubes are required to increase the solar energy capture efficiency and capacity. The fluidization phenomena differ with the tube length, and freely bubbling fluidization will be transformed into slugging, thus hampering the heat transfer. The behavior of Geldart-A powders in tall tubes of small I.D. has not been extensively studied. The research experimentally investigated the different fluidization modes in a 4 m long tube, and demonstrated the occurrence of freely bubbling at the bottom section of the bed, and slugging from a bed depth in excess of about 1.25 m. Slug characteristics (frequency, length, velocity) were measured and correlated. The results were used to validate 3D numerical simulations based on an Euler-Euler approach in the NEPTUNE_CFD code applied to a fine mesh of 15,000,000 cells. A positive match between experimental and simulation results concerning frequency and velocity of large bubble structures was obtained. The effect of mesh refinement on the slugging behavior prediction was discussed.

Mots clés: Upflow Bubbling Fluidized Bed; Solar receiver; Slugging; NEPTUNE_CFD code simulation; Euler-Euler; Geldart A powders

Domaines: Génie chimique; Génie des procédés

Florian Sabatier, Renaud Ansart, Zhang Huili, Jan Baeyens, Olivier Simonin. Experiments support simulations by the NEPTUNE_CFD code in an Upflow Bubbling Fluidized Bed reactor. Chemical Engineering Journal, 2020, ⟨10.1016/j.cej.2019.123568⟩. ⟨hal-02735384⟩