Hydrogen production by supercritical water gasification of biomass: Particle and residence time distribution in fluidized bed reactor

Abstract

Particle distribution and residence time distribution (RTD) in supercritical water fluidized bed reactor (SCWFBR) greatly affect the hydrogen yield through determining the two phase mixing and reaction time. A Eulerian model incorporating the kinetic theory for solid particles was applied to simulate the solid distribution and RTD of feeding materials. The effect of four types of feeding methods and feeding rates on solid distribution and RTD were evaluated based on the simulation results. Results showed that double symmetrical feeding pipe with an feeding mouth angle of 45° provides more uniform solid distribution and longer residence time compared with those of other three types. A nonlinear relationship between feeding rate and RTD was observed, and an optimum feeding rate was found to be related to the best solid-fluid mixing in the study.