Towards Biomass Gasification Enhanced by Structured Iron-Based Catalysts

The main drawback for the development of biomass gasification technology is tar conversion. Among the various methods for tar abatement, the use of catalysts has been proposed in the literature. Most of the works reported in the literature on catalytic systems for biomass tar conversion refers to catalysts in the form of powder; however, deactivation occurs by fast clogging with particulates deriving from biomass gasification. The integration of catalytic filter element for particle and tar removal directly integrated into the freeboard of the reactor is a new concept recently proposed and patented. In this context, this paper evaluates the possibility to integrate a structured iron-based catalytic monolith in the freeboard of a fluidized bed gasifier to enhance biomass gasification. The effectiveness of using a monolith for gas conditioning has been preliminarily verified. The limited effect on the gas production and composition seems to be related to the limited range of operating conditions explored in this work rather than to the low activity of the iron-based catalyst. Further studies to optimize the performance and to assess the possible deactivation of the catalyst due to coke deposition must be carried out.

Application of Scaling-Law and CFD Modeling to Hydrodynamics of Circulating Biomass Fluidized Bed Gasifier

Two modeling approaches, the scaling-law and CFD (Computational Fluid Dynamics) approaches, are presented in this paper. To save on experimental cost of the pilot plant, the scaling-law approach as a low-computational-cost method was adopted and a small scale column operating under ambient temperature and pressure was built. A series of laboratory tests and computer simulations were carried out to evaluate the hydrodynamic characteristics of a pilot fluidized-bed biomass gasifier. In the small scale column solids were fluidized. The pressure and other hydrodynamic properties were monitored for the validation of the scaling-law application. In addition to the scaling-law modeling method, the CFD approach was presented to simulate the gas-particle system in the small column. 2D CFD models were developed to simulate the hydrodynamic regime. The simulation results were validated with the experimental data from the small column. It was proved that the CFD model was able to accurately predict the hydrodynamics of the small column. The outcomes of this research present both the scaling law with the lower computational cost and the CFD modeling as a more robust method to suit various needs for the design of fluidized-bed gasifiers.