Design and Initial Testing of a Spouted-Bed Reactor for Biomass Catalytic Pyrolysis

Spouted-bed reactors are ideal for the catalytic pyrolysis of biomass due to their ability to handle larger particles, large particle size distributions, and differences in solid densities. They also provide a good mixing and decouple residence times of gas and solids; thus, gas residence times and unwanted secondary biomass reactions are reduced. In this study, a bench-scale conical spouted-bed biomass catalytic reactor has been designed, considering different particle properties, geometric factors and important hydrodynamic parameters. The design analysis aimed at identifying gas flows capable of generating a stable spouted-bed regime in the conical reactor, while providing flexibility in the catalyst to biomass ratios that the unit can handle.

The biomass reactor setup is shown in Figure 1. It includes: 1) a conical quartz reactor with a gas distribution grid at the bottom, 2) two biomass feeders providing the capability for batch and continuous operation, 3) cooler and condenser for the separation of the liquid products, weighing scale for real-time measurement of the liquid product yield, 4) filter capable of removing the remaining condensable liquid droplets and fine solid particles, 5) liquid and gas collection systems and 6) a Fourier Transform Infrared (FTIR) spectrometer for real time gas composition analysis and the simultaneous use of dynamic simulation and experimentation for the analysis of reaction kinetics and process optimization. The reactor is capable of converting lignocellulosic and other types of biomass to liquid fuels and/or synthesis gas, using N₂, H₂O or CO₂ as the fluidization gas. Figure 2 illustrates ranges of stable operation in the relevant hydrodynamic regimes. The regime calculated for the reactor development (red-colored area) demonstrates that conical spouted beds have a wide range of operating regimes, which makes them ideal for the variability of biomass density and particle diameter.

 

Fig. 1 Flow diagram of the designed biomass reactor	Fig. 2 Hydrodynamic flexibility of conical spouted-bed reactors

In this presentation, the applicability of literature correlations on conical spouted bed reactors and the range of hydrodynamic regimes in conical spouted-bed spouted conical fluidization will be shown. Finally results of the biomass catalytic reactor initial testing and a comparison of biomass pyrolysis selectivity under different catalyst to biomass weight ratios, heating rates, and temperatures will be presented.