Multiphase jet penetration in gas-solid systems

Abstract

Thermochemical conversion of biomass in fixed/fluidized bed reactors requires efficient feedstock penetration and dispersion through reliable feed injection systems. Pneumatic biomass injection produces a gas-solid jet in the reactor that requires proper momentum to disperse the feedstock. Assessing multiphase jet penetration in fluidized beds is challenging because of system's complexity, opaqueness and lack of a universal measurement technique adapted for tracking the associated phenomena. In this work, three measurement techniques (fluorescent particle tracking, pitot tubes and Electric Capacitance Tomography (ECVT)) were employed and compared to assess the penetration of air-biomass jets into fixed/fluidized beds. Results from all techniques indicated that the jet penetration increased with solids mass flux, and jets with similar momentum provide greater penetration in fluidized beds compared to fixed beds. Tridimensional jet propagation and biomass concentration across the jet length were obtained for different operating conditions providing a useful database for CFD and other mechanistic models validation.