Multi-fluid model with variable particle density and diameter based on mass conservation at the particle scale

• Mass conservation at particle scale determines particle density and diameter.
• Variable density and diameter model overcome the limitation of constant diameter.
• Biomass pyrolysis was simulated by MFM with variable density and diameter.
• Predicted results were affected by particle diameter model and char density.

The multi-fluid model (MFM) has been widely used in the simulation of gas–solid fluidized bed reactor, in which the density and diameter of particles normally change due to the heterogeneous reactions. However, the particle diameter always keeps constant although the particle density varies along with reaction in the previous MFM, which may disobey the law of mass conservation at the particle scale. Therefore, in order to overcome the limitation of constant diameter in the previous MFM, the biomass pyrolysis reaction was taken as an example to develop the variable particle density and diameter model based on the mass conservation at the particle scale, which was successfully incorporated into MFM to simulate the biomass pyrolysis process in a fluidized bed reactor. The results indicate that the segregation/mixing and entrainment behavior are significantly affected by the variation model of particle density and diameter and the species density in the solid phase.

Figure optionsDownload as PowerPoint slide