Numerical Simulation on Effects of Biomass Type on Its Fast Pyrolysis in Fluidized Bed Reactor

Bio-oil (or tar) production by the fast pyrolysis of biomass is one of the important technological paths for efficient utilization and conversion of biomass. However, there are many types of biomasses with different compositions. There is an urgent need to select the biomass type that is more suitable for fast pyrolysis to produce bio-oil. In this work, the fast pyrolysis characteristics of three main components of biomass (cellulose, hemicellulose, and lignin) in a fluidized bed reactor were studied by establishing a comprehensive mathematical model of multiphase flow-heat transfer-pyrolysis reaction in the fast pyrolysis process of biomass in a fluidized bed reactor using a numerical simulation method. The fast pyrolysis characteristics of two typical biomasses such as hardwood and softwood with different contents of three main components were further analyzed. The results show that the yield of bio-oil or tar is 3% higher and the yield of biochar is 6% lower for the fast pyrolysis of hardwood compared to softwood at 773 K. Simulation results demonstrated that hardwood with high hemicellulose content and low lignin content is an ideal feed for bio-oil production by fast pyrolysis.