CFD study of gas–solid behavior in downer reactors: An Eulerian–Eulerian approach

Toward Low-Temperature Coal Gasification: Experimental and Numerical Studies of Thermochemical Coal Conversion Considering the Interactions between Volatiles and Char Particles

“…Gas-solid two-phase mixed flows are key phenomena and of particular interest for understanding the downer reactor. Ropelato et al (2005) proposed an Eulerian-Eulerian approach for predicting fluid dynamics in the downer reactor, with good agreement between the experimental data and model predictions. Fushimi et al (2012) also used an Eulerian-Eulerian method to investigate the degree of solid-solid mixing in the downer unit by simulating the hydrodynamics of hot sand, cold sand, and air, as well as the heat transfer among them.…”

Analysis of solid particle mixing in inclined fluidized beds using DEM simulation

“…Their simulation indicates that the simulated solid concentration predicted by the Wen and Yu/Ergun equation is underestimated but the EMMS approach could provide the simulated outlet solid flux and voidage profile consistent with experimental results. Then, Ropelato et al [6] also report that CFD technique with first (HIP-WIND) and second order (HIGHER UPWIND) interpolation schemes could provide simulated results of phase distribution consistent with experimental data. However, there is limitation on consideration of the interaction among each particle.…”

“…For the so-called dense system of which predominant portion is particles, there is limitation in clear observation of solid mixing phenomena taking place inside the equipment via experiments though there are some techniques proposed [1][2][3][4]. Consequently, numerical simulation is proposed and exploited to provide an insight into the solid mixing within fluidization [5][6][7][8][9][10][11].…”

“…(11) for definition (kg m −3 s −1 ) δ displacement of a solid particle (m) ε void fraction η damping coefficient µ gas viscosity (N s m −2 ) µ f friction coefficient ρ g gas density (kg m −3 ) ρ p solid particle density (kg m −3 ) σ 0 standard deviation for a completely segregated mixturė ω angular acceleration (radian s −2 ) Subscripts g gas phase n normal direction p solid phase t tangential direction studies of gas-solid two-phase systems have been carried out using various numerical models, e.g. the two-fluid model [4][5][6], the discrete element method (DEM) [7][8][9][10][11], the hard sphere model [12] and the lattice gas cellular automation approach [13]. Yang et al [5] have employed two-fluid CFD method with the energy-minimization multi-scale (EMMS) approach to investigate the dependence of drag coefficient on solid cluster structure within concurrent-up gas-solid flow in a riser.…”

Modeling of gas/particle flow in coal conversion with a drop tube reactor using a lumped kinetic model accounting volatiles–char interaction

“…Computational fluid dynamics (CFD) has been employed as a powerful tool for obtaining a deeper understanding of the gas-solid mixed flows employed in downer reactors [22][23][24]. Ropelato et al [22] proposed an Eulerian-Eulerian approach for predicting fluid dynamics in the downer reactor with good agreement between experimental data and model predictions.…”