Investigation of Gasification Reaction of Pulverized Char under N₂/CO₂ Atmosphere in a Small-Scale Fluidized Bed Reactor

A method for the experimental investigation of gas-solid reactions in a small-scale fluidized bed reactor (FBR) is presented. This methodology enables high heating rates (≈10⁴ K/s), long timescale observation (up to several hours), operation with small fuel particles (≈100 μm), and accurate control of reaction conditions. In this study, the gasification reaction of biomass-based char particles with carbon dioxide-nitrogen gas mixtures is investigated under atmospheric pressure. On varying process temperature and feed-gas composition over a wide range, consistent results are realized (temperature is varied between 1173 and 1373 K, while the CO₂ concentration is adjusted in an interval of 20% up to 80%). Carbon conversion curves and reaction rates are established from real-time gas product analysis by FTIR spectrometry through a detailed data analysis procedure. This procedure employs a particle surface-evolution model and accounts for sampling system signal attenuation. The obtained reaction rates are used to demonstrate the determination of kinetic parameters for different kinetic approaches concerning the heterogeneous CO₂ gasification (Boudouard reaction). Throughout this study, a comparison of both different surface-evolution models as well as kinetic approaches with experimental results is performed for the inspection of best consistency.