Numerical analysis on the transport properties and residence time distribution of ribbon biomass particles in a riser reactor based on CFD-DEM approach

Abstract

A bended ribbon biomass particle model was developed to explore the dynamic transport properties inside a riser reactor. Residence time distribution (RTD) of the particles was analyzed by using the Eulerian-Lagrange method. The effects of sampling height, particle density, particle size and gas-to-solid mass ratio on RTD were investigated. The coupled Computational Fluid Dynamics and Discrete Element Method (CFD-DEM) model was verified firstly by experimental data on pressure drop and residence time distribution density function. The simulation results demonstrated that the ribbon biomass particles display a typical annular-core spatial distribution during transportation. The RTD of particles exhibit an approximate single-peaked normal distribution. The mean residence time (MRT) can reach up to 0.7 s when the particle density is 1200 kg/m3. Particle with higher density has longer mean residence time. The flow patterns are closer to plug flow if particle length over 12 mm. The particle flow pattern is not sensitive to changes in particle density and size, while the gas-to-material mass ratio has a significant impact on it.