The Study Of Biomass Particle Movement Behavior In The Suction Moving Bed

Biomass pyrolysis is a technology using chemical method to convert biomass into liquid bio-oil product replacing increasingly scarce fossil energy.The core of the biomass pyrolysis process is the thermal cracking reactor.At present,the low heat transfer efficiency among biomass pyrolysis reactors caused the heating rate required for the thermal cracking of the biomass can not be satisfied and lower liquid bio-oil product yield,etc.A gas-solid co-flow suction moving bed reactor was designed by our group as the core reactor for cold mold experiment equipment,which was employed to study sawdust particles flow in the reactor.The effects of different incline angles on the flow characteristics of the particles in the reactor were investigated by changing the reactor structure and the incline angle of the reactor.Based on FLUENT,a two-dimensional mathematical model of mass,momentum and energy coupling transfer was established by using the Euler-Euler gas-solid multiphase flow model.The flow state of the particles in the suction moving bed was simulated and analyzed.The mainly work is as follows:(1)Designing the structure of the suction moving bed suitable for the pyrolysis reaction of biomass.The total height of the experimental equipment is 1300 mm,which mainly includes the preheating section with the height of 400 mm and the inner diameter of 200mm;the transition section which connecting the preheating section and the reaction section with the height of 100mm;the reaction section with the height of 800 mm,and with the diameter of 120 mm,the cyclone separator with the standard diameter D = 90 mm.(2)The axial and radial concentration distributions of the material of Set 1~3component in the suction moving bed were studied by experiments,and the reactorwith different incline angles(? = 30°,45°and 60°)which the concentration distribution of biomass particles of axial and radial were studied either;(3)The distribution of axial and radial concentration of particles in the suction moving bed reactor was simulated and analyzed by FLUENT,and the accuracy of the model was verified by comparison with experimental results;(4)Using FLUENT to simulate the effect of the incline angle of the reactor on the gas-solid two-phase flow in the suction moving bed reactor.The experimental results and simulation results show that the concentration of particles in the suction moving bed reactor tends to be low on center with high on both sides,and the particle concentration by the reactor walls increases,and the momentum transfer between particles increases,which is beneficial to gas-solid two-phase heat transfer and mass transfer.In the Set1~Set 3 particle size range,the particles of the Set2 component were 0.2730 kg / m3 in the reactor reaction zone and 3.16% lower than the Set 1 component,(u = 0.26 m / s,0.30 m / s,0.34 m / s),the gas flow rate u = 0.30 m / s was the highest in the three different gas flow rates(u = 0.26 m / s,0.30 m / s,0.34 m / s);The simulation results are coincide with the experimental results,and the correctness of the selected model and equation is proved.When the incline angle of the reactor is ? = 60 °,the biomass particles are in the best flow state inside the reactor.The experimental results provide guidance for the industrial production of biomass pyrolysis,which has the suction moving bed reactor as core,meanwhile provides a theoretical basis for the study of biomass pyrolysis.