Simulation of biomass-steam gasification in fluidized bed reactors: Model setup, comparisons and preliminary predictions

- A user-defined solver for biomass steam gasification in fluidized bed is built.
- The solver is tested against experimental data in literature and works well.
- Biomass steam gasification in the DFB at UBC is preliminary predicted.
- Flue gas and syngas can be well separated by the U-bend and cyclone.
- Dry N2-free syngas is composed of 55% H2, 20% CO, 20% CO2 and 5% CH4.

A user-defined solver integrating the solid-gas surface reactions and the multi-phase particle-in-cell (MP-PIC) approach is built based on the OpenFOAM software. The solver is tested against experiments. Then, biomass-steam gasification in a dual fluidized bed (DFB) gasifier is preliminarily predicted. It is found that the predictions agree well with the experimental results. The bed material circulation loop in the DFB can form automatically and the bed height is about 1 m. The voidage gradually increases along the height of the bed zone in the bubbling fluidized bed (BFB) of the DFB. The U-bend and cyclone can separate the syngas in the BFB and the flue gas in the circulating fluidized bed. The concentration of the gasification products is relatively higher in the conical transition section, and the dry and nitrogen-free syngas at the BFB outlet is predicted to be composed of 55% H2, 20% CO, 20% CO2 and 5% CH4.