We present an Euler-Lagrange method for the simulation of wood gasification in a bubbling fluidized bed. The gas phase is modeled as a continuum using the 2D Navier-Stokes equations and the solid phase is modeled by a...We present an Euler-Lagrange method for the simulation of wood gasification in a bubbling fluidized bed. The gas phase is modeled as a continuum using the 2D Navier-Stokes equations and the solid phase is modeled by a Discrete Element Method （DEM） using a soft-sphere approach for the particle collision dynamic. Turbulence is included via a Large-Eddy approach using the Smagorinsky sub-grid model. The model takes into account detailed gas phase chemistry, zero-dimensional modeling of the pyrolysis and gasification of each individual particle, particle shrinkage, and heat and mass transfer between the gas phase and the particulate phase. We investigate the influence of wood feeding rate and compare exhaust gas compositions and temperature results obtained with the model against experimental data of a laboratory scale bubbling fiuidized bed reactor.展开更多
A Euler-Lagrangian simulation was employed for a comprehensive parameter study of wood gasification in a fluidized charcoal bed. The parameters that were varied include the initial bed temperature, fuel mass flow rate...A Euler-Lagrangian simulation was employed for a comprehensive parameter study of wood gasification in a fluidized charcoal bed. The parameters that were varied include the initial bed temperature, fuel mass flow rate, inert tar fraction, and kinetic energy losses caused by particle-particle and particle-wall colli- sions. The results of each parameter variation are compared with a base scenario, previously described in detail in Part I of this study （Gerber ＆ Oevermann, 2014）. The results are interpreted by comparing the reactor outlet temperature, averaged particle temperature, overall wood mass, overall charcoal mass, concentrations of several gaseous species, and axial barycenter data for particles obtained with differ- ent sets of parameters. The inert tar fraction and fuel mass flow rate are the most sensitive parameter, while the particle-particle and particle-wall contact parameters have only a small impact on the results. Increasing the reactive tar components by 19% almost doubled the amount of reactive tars at the reac- tor outlet, while decreasing the restitution coefficients of the particle collisions by 0.2 results in higher overall gas production but almost no change in bed height. Herein, our numerical results are discussed in detail while assessing the model restrictions.展开更多
文摘We present an Euler-Lagrange method for the simulation of wood gasification in a bubbling fluidized bed. The gas phase is modeled as a continuum using the 2D Navier-Stokes equations and the solid phase is modeled by a Discrete Element Method （DEM） using a soft-sphere approach for the particle collision dynamic. Turbulence is included via a Large-Eddy approach using the Smagorinsky sub-grid model. The model takes into account detailed gas phase chemistry, zero-dimensional modeling of the pyrolysis and gasification of each individual particle, particle shrinkage, and heat and mass transfer between the gas phase and the particulate phase. We investigate the influence of wood feeding rate and compare exhaust gas compositions and temperature results obtained with the model against experimental data of a laboratory scale bubbling fiuidized bed reactor.
文摘A Euler-Lagrangian simulation was employed for a comprehensive parameter study of wood gasification in a fluidized charcoal bed. The parameters that were varied include the initial bed temperature, fuel mass flow rate, inert tar fraction, and kinetic energy losses caused by particle-particle and particle-wall colli- sions. The results of each parameter variation are compared with a base scenario, previously described in detail in Part I of this study （Gerber ＆ Oevermann, 2014）. The results are interpreted by comparing the reactor outlet temperature, averaged particle temperature, overall wood mass, overall charcoal mass, concentrations of several gaseous species, and axial barycenter data for particles obtained with differ- ent sets of parameters. The inert tar fraction and fuel mass flow rate are the most sensitive parameter, while the particle-particle and particle-wall contact parameters have only a small impact on the results. Increasing the reactive tar components by 19% almost doubled the amount of reactive tars at the reac- tor outlet, while decreasing the restitution coefficients of the particle collisions by 0.2 results in higher overall gas production but almost no change in bed height. Herein, our numerical results are discussed in detail while assessing the model restrictions.
