Autothermal pyrolysis is the process of converting biomass into biofuels and other chemical products where the energy for the pyrolysis process is obtained by partial oxidation of products. The sand acts as the fluidizing medium and heat carrier inside the fluidized bed reactor. Perfect mixing of biomass with sand particles enables better heat transfer, which further facilitates the devolatilization process to produce higher yields. The objective of this study is to use a multi-fluid Euler-Euler methodology to predict mixing and segregation phenomena in bi-dispersed flows. The method was extended to simulate the hydrodynamics of biomass and sand particles inside a fluidized bed.

Further, an attempt was made to quantify mixing using local and global mixing indices, which are insensitivity to sampling volume. These mixing quantification methods were used to compare two designs of biomass fluidized bed reactors with different positions of feeder inlets. The results showed the expected trend in mixing index values by changing the location of feeder inlet, but the difference was not significant as other flow parameters drove the mixing. The methods and findings from this work would be useful to quantify the mixing in bi-dispersed flows using Euler-Euler numerical methods and perform design evaluations.