Circulating fluidized bed combustion reactor: Computational Particle Fluid Dynamic model validation and gas feed position optimization

Abstract A 3D Computational Particle Fluid Dynamic (CPFD) model is validated against experimental measurements in a lab-scale cold flow model of a Circulating Fluidized Bed (CFB). The model prediction of pressure along the riser, downcomer and siphon as well as bed material circulation rates agree well with experimental measurements. Primary and secondary air feed positions were simulated by varying the positions along the height of the reactor to get optimum bed material circulation rate. The optimal ratio of the height of primary and secondary air feed positions to the total height of the riser are 0.125 and 0.375 respectively. The model is simulated for high-temperature conditions and for reacting flow including combustion reactions. At the high temperature and reaction conditions, the bed material circulation rate is decreased with the corresponding decrease in pressure drop throughout the CFB for the given air feed rate.

[1]  Hermann Hofbauer,et al.  Comparison of dual fluidized bed steam gasification of biomass with and without selective transport of CO2 , 2009 .

[2]  Ng Niels Deen,et al.  Review of discrete particle modeling of fluidized beds , 2007 .

[3]  C. Wen.  Mechanics of Fluidization , 1966 .

[4]  P. J. O'rourke,et al.  The multiphase particle-in-cell (MP-PIC) method for dense particulate flows , 1996 .

[5]  Stefan Heinrich,et al.  CPFD simulation of circulating fluidized bed risers , 2013 .

[6]  L. S. Leung,et al.  A quantitative definition and flow regime diagram for fast fluidization , 1986 .

[7]  Hiromi Takeuchi,et al.  Regime classification of macroscopic gas-solid flow in a circulating fluidized bed riser , 1992 .

[8]  J. Grace.  Contacting modes and behaviour classification of gas—solid and other two-phase suspensions , 1986 .

[9]  P. J. O'rourke,et al.  An improved collision damping time for MP-PIC calculations of dense particle flows with applications to polydisperse sedimenting beds and colliding particle jets , 2010 .

[10]  F. Hamdullahpur,et al.  Gas Mixing in Circulating Fluidized Beds with Secondary Air Injection , 2004 .

[11]  M. Duduković,et al.  A method for estimating the solids circulation rate in a closed-loop circulating fluidized bed , 2001 .

[12]  Ugur Yildirim,et al.  Two dimensional numerical computation of a circulating fluidized bed biomass gasifier , 2013, Comput. Chem. Eng..

[13]  Lawrence J. Shadle,et al.  Improvement of continuous solid circulation rate measurement in a cold flow circulating fluidized bed , 2008 .

[14]  Hsiaotao Bi,et al.  Types of choking in vertical pneumatic systems , 1993 .

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

[16]  Shiqiu Gao,et al.  Necessary parameters for specifying the hydrodynamics of circulating fluidized bed risers—a review and reiteration , 2003 .

[17]  Hermann Hofbauer,et al.  Model for biomass char combustion in the riser of a dual fluidized bed gasification unit: Part 1 — Model development and sensitivity analysis , 2008 .

[18]  Hsiaotao Bi,et al.  Flow regime diagrams for gas-solid fluidization and upward transport , 1995 .

[19]  Arthur M. Squires,et al.  The Fast Fluidized Bed , 1976 .

[20]  D. Snider,et al.  Heterogeneous gas chemistry in the CPFD Eulerian–Lagrangian numerical scheme (ozone decomposition) , 2010 .

[21]  Masayuki Horio,et al.  A Comprehensive Pressure Balance Model of Circulating Fluidized Beds , 1998 .

[22]  Hermann Hofbauer,et al.  Model development and validation: Co-combustion of residual char, gases and volatile fuels in the fast fluidized combustion chamber of a dual fluidized bed biomass gasifier , 2007 .

[23]  P. J. O'rourke,et al.  Eulerian–Lagrangian method for three-dimensional thermal reacting flow with application to coal gasifiers , 2011 .

[24]  L. S. Leung.  Vertical pneumatic conveying: a flow regime diagram and a review of choking versus non-choking systems , 1980 .

[25]  D. Snider.  An incompressible three-dimensional multiphase particle-in-cell model for dense particle flows , 2001 .