Experimental and simulated study on fluidization characteristics of particle shrinkage in a multi-chamber fluidized bed for biomass fast pyrolysis

In a multi-chamber fluidized bed, the stabilization of fluidization of semi-coke particles at different pyrolysis ages and the reduction of backmixing of particles at different pyrolysis stages play an important role in improving the pyrolysis efficiency of biomass. In this paper, this paper first obtains the particle shrinkage law of biomass particles at different temperatures through the tube furnace pyrolysis experiment, and the more universal mathematical model of particle shrinkage was obtained through one-step reaction model and particle shrinkage core model. Then, particle shrinkage model is imported into DEM through open source API. CFD-DEM cold simulation was used to study the fluidization state at different pyrolysis temperatures, and the reliability of the model was verified by particle image velocimetry (PIV) experiment. The simulated flow field of each chamber are in good agreement with the experimental data. The residence time distribution and axial particle size change of each compartment are also analyzed.

Automated summary

This paper investigates the particle shrinkage characteristics of biomass particles at different temperatures, establishes a mathematical model, conducts CFD-DEM simulation to study fluidization states in a multi-chamber fluidized bed at different pyrolysis temperatures, and verifies the model with PIV experiments. The study also provides analysis on residence time distribution and axial particle size variation in each compartment.