Numerical investigation on the effect of draft plates on spouting stability and gas–solid characteristics in a spout-fluid bed

Abstract Numerical simulation of dense gas–solid motion in a spout-fluid bed was carried out using the computational fluid dynamics coupled with discrete element method (CFD–DEM), in which the gas and solid motion are solved in the Eulerian and Lagrangian framework, respectively. After validating the simulated results with experimental data, the main cause of spouting instability was first identified, followed by evaluating the effect of draft plate length on spouting stability, pressure signals, and gas–solid hydrodynamics in the system. The results demonstrate that the onset of spout dancing, which is a type of spouting instability, is primarily due to the merging of the rising bubbles in the annulus with the spouting channel, which can be circumvented by the presence of draft plates. Increasing the draft plate length diminishes the mean pressure in the spouting inlet and the corresponding peak value of the power spectrum, and the correlation coefficient of pressure signals in the spout and background inlets. Regarding effect on the gas–solid hydrodynamics, a longer draft plate length leads to a more dilute upper spout, a higher spoutable height, higher voidage in the central fountain region, higher vertical gas flux (Fgz) and solid velocity (Usz) in the central axis, lower Fgz and Usz near the wall, and lower vertical solid flux (Fsz) overall. The optimization of the draft plate length depends on a balance between spout stability and solid circulation rate, since the former increases but the latter decreases with draft plate length.

[1]  John R. Grace,et al.  Voidage and particle velocity profiles in a spout-fluid bed , 2000 .

[2]  Stefan Heinrich,et al.  Experimental investigations of a pseudo-2D spout fluidized bed with draft plates , 2013 .

[3]  Leo A. Behie,et al.  SOLIDS CIRCULATION IN SPOUTED AND SPOUT-FLUID BEDS WITH DRAFT-TUBES , 1990 .

[4]  J. Grace,et al.  Spouted, fluidized and spout-fluid bed combustion of bituminous coals , 1988 .

[5]  L. Shadle,et al.  Comparison of full-loop and riser-only simulations for a pilot-scale circulating fluidized bed riser , 2014 .

[6]  Rui Xiao,et al.  DEM simulation of particle mixing in flat-bottom spout-fluid bed , 2010 .

[7]  Mingyao Zhang,et al.  DEM simulation of gas-solid flow behaviors in spout-fluid bed , 2006 .

[8]  J. Bilbao,et al.  Kinetic study of fast pyrolysis of sawdust in a conical spouted bed reactor in the range 400–500 °C , 2001 .

[9]  Kun Luo,et al.  Particle‐scale investigation of the solid dispersion and residence properties in a 3‐D spout‐fluid bed , 2014 .

[10]  Ng Niels Deen,et al.  Investigations on the spouting stability in a prismatic spouted bed and apparatus optimization , 2015 .

[11]  Ng Niels Deen,et al.  Experimental study of hydrodynamics and thermal behavior of a pseudo‐2D spout‐fluidized bed with liquid injection , 2015 .

[12]  Ng Niels Deen,et al.  Numerical Simulation of Dense Gas-Solid Fluidized Beds: A Multiscale Modeling Strategy , 2008 .

[13]  John R. Grace,et al.  Study of wall boundary condition in numerical simulations of bubbling fluidized beds , 2010 .

[14]  Jam Hans Kuipers,et al.  Flow regimes in a spout-fluid bed : A combined experimental and simulation study , 2005 .

[15]  Marek Markowski,et al.  Drying Behavior of Carrots Dried in a Spout–Fluidized Bed Dryer , 2007 .

[16]  Baosheng Jin,et al.  Experiment on particle mixing in flat-bottom spout–fluid bed , 2009 .

[17]  R. Xiao,et al.  High-temperature air/steam-blown gasification of coal in a pressurized spout-fluid bed , 2006 .

[18]  Todd Pugsley,et al.  Simulation and experimental validation of a freely bubbling bed of FCC catalyst , 2003 .

[19]  Ng Niels Deen,et al.  Influence of rolling friction on single spout fluidized bed simulation , 2012 .

[20]  C. R. Kfuri,et al.  A Comparative Study of Spouted and Spout-Fluid Beds for Tablet Coating , 2005 .

[21]  J.A.M. Kuipers,et al.  Numerical investigations of a pseudo-2D spout fluidized bed with draft plates using a scaled discrete particle model , 2013 .

[22]  David Parker,et al.  Numerical and experimental study on multiple-spout fluidized beds , 2011 .

[23]  J. Grace,et al.  Hydrodynamic investigation of gas-solid flow in rectangular spout-fluid bed using CFD-DEM modeling , 2015 .

[24]  A. Yu,et al.  Rolling friction in the dynamic simulation of sandpile formation , 1999 .

[25]  Tingwen Li,et al.  Cartesian grid simulations of bubbling fluidized beds with a horizontal tube bundle , 2011 .

[26]  M. Sommerfeld,et al.  Multiphase Flows with Droplets and Particles , 2011 .

[27]  Stefan Heinrich,et al.  An experimental study of the effect of collision properties on spout fluidized bed dynamics , 2011 .

[28]  Jianren Fan,et al.  Numerical investigation of the time-related properties of solid phase in a 3-D spout-fluid bed , 2015 .

[29]  Hiroshi Nagashima,et al.  Flow regimes and vertical solids conveying in a spout-fluid bed with a draft tube , 2011 .

[30]  Jpk Seville,et al.  PEPT and discrete particle simulation study of spout‐fluid bed regimes , 2008 .

[31]  J.A.M. Kuipers,et al.  Experimental and numerical investigations of a pseudo-2D spout fluidized bed with draft plates , 2015 .

[32]  Goodarz Ahmadi,et al.  CFD studies of solids hold-up distribution and circulation patterns in gas-solid fluidized beds , 2010 .

[33]  David Parker,et al.  Numerical and experimental study on spout elevation in spout-fluidized beds , 2012 .

[34]  Min Zhang,et al.  Numerical study on spout elevation of a gas-particle spout fluidized bed in microwave-vacuum dryer , 2014 .

[35]  Animesh Dutta,et al.  An investigation of MSW gasification in a spout-fluid bed reactor , 2008 .

[36]  Abhay V. Patil,et al.  Computational study of particle temperature in a bubbling spout fluidized bed with hot gas injection , 2015 .

[37]  Jian Fei Chen,et al.  Assessment of rolling resistance models in discrete element simulations , 2011 .

[38]  Kun Luo,et al.  LES–DEM investigation of an internally circulating fluidized bed: Effects of gas and solid properties , 2013 .

[39]  Ng Niels Deen,et al.  CFD–DEM model for coupled heat and mass transfer in a spout fluidized bed with liquid injection , 2016 .

[40]  J. Chew,et al.  Influence of operating parameters and flow regime on solid dispersion behavior in a gas–solid spout-fluid bed , 2016 .

[41]  Baosheng Jin,et al.  Three-dimensional Simulation of Gas/Solid Flow in Spout-fluid Beds with Kinetic Theory of Granular Flow , 2006 .

[42]  Seyyed Hossein Hosseini,et al.  CFD simulation of gas–solid flow in a spouted bed with a non-porous draft tube , 2009 .

[43]  D. Gidaspow.  Multiphase Flow and Fluidization: Continuum and Kinetic Theory Descriptions , 1994 .

[44]  C. Thornton,et al.  A comparison of discrete element simulations and experiments for ‘sandpiles’ composed of spherical particles , 2005 .

[45]  Javier Bilbao,et al.  Modelling batch drying of sand in a draft-tube conical spouted bed , 2011 .

[46]  Ng Niels Deen,et al.  Spout fluidized beds: Recent advances in experimental and numerical studies , 2013 .

[47]  A. Gosman,et al.  Solution of the implicitly discretised reacting flow equations by operator-splitting , 1986 .

[48]  Jpk Seville,et al.  The influence of DEM simulation parameters on the particle behaviour in a V-mixer , 2002 .

[49]  Javier Bilbao,et al.  Defluidization modelling of pyrolysis of plastics in a conical spouted bed reactor , 2005 .

[50]  J.A.M. Kuipers,et al.  Gas-Solid Turbulent Flow in a Circulating Fluidized Bed Riser; Numerical Study of Binary Particle Mixtures , 2009 .

[51]  Zhiwei Chen.  Hydrodynamics, stability and scale-up of slot-rectangular spouted beds , 2008 .

[52]  Luca Marmo,et al.  Low temperature drying of pomace in spout and spout-fluid beds , 2007 .

[53]  C. Hrenya,et al.  Axial segregation in bubbling gas-fluidized beds with Gaussian and lognormal distributions of Geldart Group B particles , 2010 .

[54]  P. Cundall,et al.  A discrete numerical model for granular assemblies , 1979 .

[55]  F. Berruti,et al.  Solids circulation in a spout‐fluid bed with draft tibe , 1988 .

[56]  Jiyu Zhang,et al.  Prediction of flow regimes in spout-fluidized beds , 2006 .

[57]  R. Xiao,et al.  Mixing and Segregation Behavior in a Spout-Fluid Bed: Effect of Particle Size , 2012 .

[58]  J. Chew,et al.  Computational study of spout collapse and impact of partition plate in a double slot‐rectangular spouted bed , 2015 .

[59]  Yurong He,et al.  Discrete particle modeling of granular temperature distribution in a bubbling fluidized bed , 2012 .

[60]  Baosheng Jin,et al.  Novel Method To Study the Particle Circulation in a Flat-Bottom Spout-Fluid Bed , 2010 .

[61]  Baosheng Jin,et al.  Flow behaviors of a large spout-fluid bed at high pressure and temperature by 3D simulation with kinetic theory of granular flow , 2007 .

[62]  Xiaoping Chen,et al.  Flow pattern and transition of rectangular spout–fluid bed , 2006 .

[63]  A. Yu,et al.  Discrete particle simulation of particulate systems: Theoretical developments , 2007 .

[64]  Wenqi Zhong,et al.  Pressure fluctuation frequency characteristics in a spout-fluid bed by modern ARM power spectrum analysis , 2005 .