Perpustakaan Digital ITB

The decarbonization of hard-to-abate sectors requires thermochemical processes that can deliver high-temperature heat while enabling inherent CO2 capture. Three-reactor chemical looping (TRCL) offers such potential through interconnected reactors. In the air reactor, oxygen carriers are oxidized by air. In the steam reactor, reduced particles react with steam to release hydrogen. In the fuel reactor, oxygen carriers are reduced while biomass undergoes thermal decomposition. Stable solid circulation is essential to sustain the process. This study investigates the cold-flow hydrodynamics of a lab-scale TRCL system using transient CFD with OpenFOAM’s denseParticleFoam solver and Large Eddy Simulation (LES). Gas flow was characterized by the fluidization number (FN), defined as the ratio of superficial velocity to the minimum fluidization velocity. A solid circulation rate of 59.53 g/s was targeted based on experimental requirements for autothermal operation. Results confirmed that this rate was achieved with 190FN in the air reactor, 2.5FN (side) and 4.5FN (recycle) or 3.5FN (double-bottom) aeration in the steam reactor, and 41.5FN and 61.5FN at the two inlets of the fuel reactor. Unlike the air and steam reactors, which do not require long particle residence, the fuel reactor must sustain extended circulation to support oxygen carrier reduction and biomass conversion. Its baffle design successfully prolonged particle transport and stabilized the flow. Residence time distribution analysis showed that biomass particles had a mean residence time of 6.1 s with most exiting within 3–12 s, while oxygen carrier particles circulated longer with a mean of 10.7 s and the majority exiting after 8–15 s. These results demonstrate that reactor geometry and aeration strategy not only stabilize hydrodynamics but also govern the chemical functionality of TRCL, providing predictive insight for scaling up the system toward clean hydrogen production.