Numerical simulation and experiment on catalytic upgrading of biomass pyrolysis vapors in V-shaped downer reactors

Abstract

Catalytic upgrading of biomass pyrolysis vapors is an effective utilization technology of biomass energy. Based on the disadvantages of commonly used reactors, the V-shaped downer reactors were designed to increase gas-solid two-phase turbulent intensity, contact frequency and then increase the catalytic efficiency in short residence time. The catalytic upgrading of pyrolysis vapors in V-shaped downer reactors in terms of hydrodynamics, chemical reaction and residence time distribution were analyzed by CFD simulation and experiment. The results indicate that the solid concentration gradient decreases while flowing down. The overall mass fraction of the bio-oil vapors is around 50%. The mean residence time of catalysts in the V-shaped reactor is 2.0 s-3.0 s. The effects on product yield and residence time distribution were investigated for optimizing product selectivity and the performance of catalysts. In this paper the optimal flow rates of gas and catalysts are v_g = 1.2 m s^-1, v_s = 0.4 m s^-1.

Keywords: CFD; Multiphase flow; Pyrolysis vapors upgrading; Residence time distribution; Tracer experiment.