Bridging the Gap Between MP-PIC CPFD Hydrodynamic Simulations and CREC-GS-Optiprobes Data in a Sand Fluidized Bed for Biomass Gasification

This study examines a sand bubbling fluidized bed containing cylindrical biomass pellets. It demonstrates the advantages of integrating fiber-optic measurements—such as those obtained with CREC-GS-Optiprobes—with CPFD Barracuda VR® 25.0.1 computational modeling. Experimental data collected by using CREC fiber-optic probes in a 43.8 cm diameter, laboratory-scale cold gasifier unit are used to validate the radial phase distributions predicted by CPFD Barracuda VR® simulations for the gas, emulsion, and biomass pellet phases. In addition, it is shown that the bubble rise velocity measurements provided by the CREC probes offer complementary insights into the limitations of CPFD Barracuda VR® simulations. These measurements highlight the importance of bubble–bubble interactions, including the “push” exerted by neighboring bubbles on a target bubble. Based on this approach, a combined experimental–computational methodology is proposed, leading to the development of a bubble rise velocity equation. This equation is expressed as a function of the isolated bubble’s axial chord and as a function of the superficial gas velocity in excess present at minimum fluidization conditions. It is anticipated that this equation will be beneficial for the design and optimization of sand fluidized bed gasifiers operating with biomass pellets, particularly by improving the prediction and capture of bubble dynamics.