The effect of rolling amplitude and period on particle distribution behavior in a rolling circulating fluidized bed

Abstract The effect of rolling amplitude and rolling period on particle distribution behaviors in a rolling circulating fluidized bed (RCFB) has been quantitatively clarified by means of the electrical capacitance tomography (ECT) technique. A series of experiments with a cold mode RCFB were performed while the rolling amplitude and rolling period varied from Θ = 2.5° to 10.0° and T = 5.0 to 15.0 s, respectively. Based on the particle distribution images captured by the ECT sensor, three main characteristics of particle distribution behavior, namely the average particle volume fraction, the particle distribution stability and the particle distribution uniformity, were quantitatively estimated. As results, the particle distribution behavior in the RCFB was dominated by the shear effect, which was derived from the inertial forces and gravity in the radial direction of the riser. The positive influence of rolling amplitude on the shear effect caused augmentation of the particle volume fraction; however, particle distribution became unstable and heterogeneous. Meanwhile, although the characteristic fluctuation frequency of particle volume fraction was dominated by the rolling period, little effect of the rolling period on the particle distribution behaviors was observed due to its minimal influence on the shear effect.

[1]  Tong Zhao,et al.  Sensor design and image accuracy for application of capacitance CT to the petroleum refinery process , 2007 .

[2]  A. Kolar,et al.  Axial heat transfer correlations in a circulating fluidized bed riser , 2013 .

[3]  Effect of inclination on gas-fluidized beds of fine cohesive powders , 2008 .

[4]  Jia Wei Chew,et al.  Particle cluster dynamics during fluidization , 2013 .

[5]  Guizhi Qiu,et al.  Measurement of gas-solids flow in loop seal and external heat exchanger in a circulating fluidized bed , 2014 .

[6]  Fan Wu,et al.  High-fidelity simulation of the 3-D full-loop gas–solid flow characteristics in the circulating fluidized bed , 2015 .

[7]  Lynn F. Gladden,et al.  The nature of the flow just above the perforated plate distributor of a gas-fluidised bed, as imaged using magnetic resonance , 2006 .

[8]  K. Harumi,et al.  Effects of the ship motion on gas–solid flow and heat transfer in a circulating fluidized bed , 2012 .

[9]  Hiroyuki Murata,et al.  Natural circulation characteristics of a marine reactor in rolling motion and heat transfer in the core , 2002 .

[10]  Chi‐Hwa Wang,et al.  Numerical studies of solid–solid mixing behaviors in a downer reactor for coal pyrolysis , 2014 .

[11]  Liang-Shih Fan,et al.  Dynamics of spiral bubble plume motion in the entrance region of bubble columns and three-phase fluidized beds using 3D ECT , 2005 .

[12]  Sreekanth Pannala,et al.  Reprint of "CFD simulations of circulating fluidized bed risers, part II, evaluation of differences between 2D and 3D simulations , 2014 .

[13]  M. S. Avval,et al.  Three dimensional heat transfer modeling of gas-solid flow in a pipe under various inclination angles , 2014 .

[14]  Junfu Lu,et al.  Experimental study of exit effect on gas-solid flow and heat transfer inside CFB risers , 2013 .

[15]  L. Martín,et al.  Estimation of the overall mass flux in inclined standpipes by means of pressure fluctuation measurements , 2012 .

[16]  Tong Zhao,et al.  Investigation of bed-to-wall heat transfer characteristics in a rolling circulating fluidized bed , 2015 .

[17]  Tong Zhao,et al.  Experimental and numerical investigation of particle distribution behaviors in a rolling circulating fluidized bed , 2014 .

[18]  J. You,et al.  An energy-based model of gas–solid transport in a riser , 2006 .

[19]  G. E. Fasching,et al.  Observations of a fluidized bed using capacitance imaging , 1993 .

[20]  Derek Geldart,et al.  The design of distributors for gas-fluidized beds , 1985 .

[21]  Wuqiang Yang,et al.  Application of electrical capacitance tomography in particulate process measurement – A review , 2014 .