Development of the Low-Tar Biomass Rapid Pyrolysis System

This project follows our previous discussion with Professor Jun-ichiro Hayashi at Kyushu University Global COE: Novel Carbon Resource Sciences after the applicant serving as a visiting professor in Kyushu University this summer. Rapid pyrolyzers generally provide heat to biomass within 1 s in the absence of air and thereby thermally transform it into charcoal, bio-oil and syngas. Most woods give maximum bio-oil yields of up to 80 wt% dry feed basis at the pyrolysis temperature of 500 ºC - 520 ºC and the bio-oil typically has a higher heating value of about 17 MJ/kg, nearly half of the conventional fuel oil. Considering the ease of the biomass feeding, common pyrolyzer design uses screw type reactor. However, these reactors fail to heat the biomass rapidly and limit the proportion of bio-oil in the final product. Potassium loaded char shows good activity in tar degradation and has been used in upgrading bio-oil from biomass pyrolysis (Sueyasu et al., 2012). This project will use fluidized bed reactors for biomass pyrolysis. The fluidizing media will be the mixture of silicone and potassium loaded char with different ratios. Fluidized beds provide rapid heat transfer through fast solids-solids heat conduction and huge heat transfer area. The effects of heating rates and tar-degradation activity of char on the compositions of the biomass pyrolyzed products are studied. In this three-year project, both the experimental and theoretical modeling works are to be carried out. In the first year, a fluidized bed pyrolyzer will be constructed. This system will allow the biomass (wood) pellets to be continuously fed to the reactor. The gaseous, liquid and solids products from biomass pyrolysis are collected from the top of the fluidized bed reactor and analyzed. In the second and third years, particles with different heat conduction coefficients and/or sizes together with char particles are used as the fluidizing media to exam the effect of heating rate/area on the composition of the biomass pyrolyzed products. Biomass pyrolysis in the fluidized bed reactor will also be simulated. The gas phase is modeled using CFD and the heating media (solid phase 1) and biomass (solid phase 2) are modeled using DEM. The detailed reaction kinetics of the discrete biomass particles will be simulated using the model developed by Professor Norinaga at Kyushu University. The CFD-DEM-reaction kinetic three-way coupling will be performed and the results will be validated by experiments.

Project ID:PB10207-1924
External Project ID:NSC102-2221-E182-051