CPFD Simulation of Gas-Solid Flow in Dense Phase Zone of Pant-Leg Fluidized Bed with Secondary Air

Document Type : Regular Article


1 Engineering Research Centre of Oil Shale Comprehensive Utilization, Ministry of Education, School of Energy and Power Engineering, Northeast Electric Power University, Jilin 132012, Jilin Province, China

2 Department of Chemical & Biological Engineering, University of British Columbia, Vancouver, V6T1Z3, Canada



Aggregation of fluidization media may appear at the dense phase region of the pant-leg fluidized bed near the incline walls. When the particles flow along the inclined wall, the friction and drag force will cause the particles to accumulate on the inclined wall, resulting in an uneven distribution of particles. The stagnant zones can be minimized by correctly arranging secondary air. Computational particle fluid dynamics (CPFD) method was used to simulate the gas-solid two-phase flow pattern in the dense phase region of pant-leg fluidized bed. Cold tests were performed on a benchtop pant-leg fluidized bed. A high speed imaging technology was used to monitor the flow pattern in the dense phase area, whereas the bubble size and residence time were compared to verify the accuracy of the simulation. The gas-solid flow patterns under various models were simulated. The influence of different secondary air velocities on the reduction of stagnant zone in the dense phase zone of the fluidized bed were predicted. The results indicated that the introduction of secondary air could effectively promote the mixing of particles, and weaken the accumulation of particles on the inclined wall surface. Moreover, secondary air can effectively promote the flow between the gas-solid two-phases and improve the combustion characteristics in the furnace.


Abbasi, A., P. E. Ege and H. I. De Lasa (2011). CPFD simulation of a fast fluidized bed steam coal gasifier feeding section. Chemical Engineering Journal 174(1), 341–350.##
Atsonios, K., A. Nikolopoulos, S. Karellas, N. Nikolopoulos, P. Grammelis and E. Kakaras (2011). Numerical investigation of the grid spatial resolution and the anisotropic character of EMMS in CFB multiphase flow. Chemical Engineering Science 66(17), 3979–3990.##
Auzerais, F. M., R. Jackson and W. B. Russel (1988). The resolution of shocks and the effects of compressible sediments in transient settling. Journal of Fluid Mechanics 195, 437–462.##
Basu, P. (2015). Circulating fluidized bed boilers,design operation and maintenance .Springer International Publishing Switzerland.##
Cahyadi, A. and A. Anantharaman (2017). Review of cluster characteristics in circulating flfluidized bed (CFB) risers. Chemical Engineering Science 158, 70-95.##
Chan, C. W., J. P. K. Seville, D. J. Parker and J. Baeyens (2010). Particle velocities and their residence time distribution in the riser of a CFB. Powder Technology 203(2), 187–197.##
Chen, C., J. Werther, S. Heinrich, H. Y. Qi and E.-U. Hartge (2013). CPFD simulation of circulating fluidized bed risers. Powder Technology 235, 238–247.##
CPFD Software (2015). Barracuda Virtual Reactor User Manual. USA: CPFD Software LLC.##
Cui, Y. and W. Q. Zhong (2021). Study on scale-up characteristics in supercritical CO2 circulating fluidized bed boiler by 3D CFD simulation. Powder Technology 394, 103–119.##
Cundall, P. A. and O. D. L. Strack (1979). A discrete numerical model for granular assemblies. Geotechnique 29(1), 47–65.##
Ergun, S. (1952). Fluid flow through packed columns. Journal of Materials Science and Chemical Engineering 48, 89–94.##
Gao, J., J. Chang, C. Lu and C. Xu (2008). Experimental and computational studies on flow behavior of gas–solid fluidized bed with disparately sized binary particles. Particuology 6(2), 59–71.##
Godlieb, W., N. G. Deen and J. A. M. Kuipers (2007). A discrete particle simulation study of solids mixing in a pressurized fluidized bed. Proceedings of the 12th International Conference On Fluidization : New Horizons in Fluidization Engineering 92, 751–758.##
Grace, J. R. and G. Sun (1991). Influence of particle size distribution on the performance of fluidized bed reactors. The Canadian Journal of Chemical Engineering 69(5), 1126–1134.##
Hartge, E. U., L. Ratschow, R. Wischnewski and J. Werther (2009). CFD-simulation of a circulating fluidized bed riser. Particuology 7(4), 283–296.##
Jenkins, J. T. and F. Mancini (1989). Kinetic theory for binary mixtures of smooth, nearly elastic spheres. Physics of Fluids A: Fluid Dynamics 1(12), 2050–2057.##
Kim, J. H. and K, Shakourzadeh (2000). Analysis and modelling of solid flow in a closed loop circulating fluidized bed with secondary air injection. Powder Technology 111(3), 179– 185.##
Kleinstreuer, C. (2003). Two-phase flow: theory and applications. CRC Press.##
Koksal, M. and F. Hamdullahpur (2004). Gas Mixing in Circulating Fluidized Beds with Secondary Air Injection. Chemical Engineering Research and Design 82(8), 979–992.##
Lan, X., X. Shi, Y. Zhang, Y. Wang, C. Xu and J. Gao (2013). Solids back-mixing behavior and effect of the mesoscale structure in CFB risers. Industrial & Engineering Chemistry Research 52(34), 11888–11896.##
Liu, H., J. Li and Q. Wang (2017). Simulation of gas–solid flow characteristics in a circulating fluidized bed based on a computational particle fluid dynamics model. Powder Technology 321, 132–142.##
Lv, B., Z. Luo, X. Deng, J. Chen, C. Fang and X. Zhu (2020). Hydrodynamics and subsequent separation of gas-solid separation fluidized bed with secondary air injection. Powder Technology 366, 197–205.##
Nardo, A. D., G. Calchetti and S. Stendardo (2018).Modeling and Simulation of an Oxygen-Blown Bubbling Fluidized Bed Gasifier using the Computational ParticleFluid Dynamics (CPFD) Approach. Journal of Applied Fluid Mechanics 11(4), 825–834.##
O’Rourke, P. J. (1981). Collective drop effects on vaporizing liquid sprays. Los Alamos National Lab., NM (USA).##
Qiu, G., J. Ye and H. Wang (2015). Investigation of gas–solids flow characteristics in a circulating fluidized bed with annular combustion chamber by pressure measurements and CPFD simulation. Chemical Engineering Science 134, 433–447.##
Raheem, D. G., B. Yılmaz and S. Özdoğan (2019). Cold Flow Simulation of a 30 kWth CFB Riser with CPFD. Journal of Applied Fluid Mechanics 13(2), 603–614.##
Shi, X., R. Sun, X. Lan, F. Liu, Y. Zhang and J. Gao (2015). CPFD simulation of solids residence time and back-mixing in CFB risers. Powder Technology 271, 16–25.##
Shi, X., X. Lan, F. Liu, Y. Zhang and J. Gao (2014). Effect of particle size distribution on hydrodynamics and solids back-mixing in CFB risers using CPFD simulation. Powder Technology 266, 135–143.##
Snider, D. M. (2001). An incompressible three-dimensional multiphase particle-in-cell model for dense particle flows. Journal of Computational Physics 170(2), 523–549.##
Snider, D. M., P. J. O’rourke and M. J. Andrews (1998). Sediment flow in inclined vessels calculated using a multiphase particle-in-cell model for dense particle flows. International Journal of Multiphase Flow 24(8), 1359–1382.##
Snider, M. Dale, S. M. Clark and P. J. O’Rourke (2011). Eulerian–Lagrangian method for three-dimensional thermal reacting flow with application to coal gasifiers. Chemical Engineering Science 66(6), 1285–1295.##
Thapa, R. K., A. Frohner, G. Tondl, C. Pfeifer and B. M. Halvorsen (2016). Circulating fluidized bed combustion reactor: Computational Particle Fluid Dynamic model validation and gas feed position optimization. Computers & Chemical Engineering 92, 180–188.##
Tu, Q. and H. Wang (2018). CPFD study of a full-loop three-dimensional pilot-scale circulating fluidized bed based on EMMS drag model. Powder Technology 323, 534–547.##
Tu, Q. and Z. Luo (2021). MP-PIC simulation of the gas-solid full-loop flow characteristics in a dual fluidized bed and validation with experimental data. Chemical Engineering Journal 421, 129835.##
Wang, Q., H. Yang, P. Wang, J. Lu, Q. Liu, H. Zhang, L. Wei and M. Zhang (2014a). Application of CPFD method in the simulation of a circulating fluidized bed with a loop seal, part I—Determination of modeling parameters. Powder Technology 253, 814–821.##
Wang, Q., H. Yang, P. Wang, J. Lu, Q. Liu, H. Zhang, L. Wei and M. Zhang (2014b). Application of CPFD method in the simulation of a circulating fluidized bed with a loop seal Part II—Investigation of solids circulation. Powder Technology 253, 822–828.##
Wen, C. and Y. Yu (1966). Mechanics of fluidization. Chemical Engineering Progress Symposium Series 62(62), 100–111.##
Xu, J. and J. X. Zhu (2011). Visualization of particle aggregation and effects of particle properties on cluster characteristics in a CFB riser. Chemical Engineering Journal 168(1), 376–389.##
Yan, J., X. F. Lu and R. Xue (2020). Validation and application of CPFD model in simulating gas-solid flow and combustion of a supercritical CFB boiler with improved inlet boundary conditions. Fuel Processing Technology 208, 106512.##
Yeoh, G. H. and J. Tu (2019). Computational techniques for multiphase flows. Butterworth-Heinemann.##
Zhang, H. D. and W. B. Li (2020). Numerical study on influence of exit geometry in gas–solid flow hydrodynamics of HDCFB riser by CPFD. Advanced Powder Technology 31, 4005–4017.##
Zhang, Y., X. Lan and J. Gao (2012). Modeling of gas-solid flow in a CFB riser based on computational particle fluid dynamics. Petroleum Science 9(4), 535–543.##
Zheng, W., M. Zhang, Y. Zhang, J. Lyu and H. Yang (2019). The effect of the secondary air injection on the gas–solid flow characteristics in the circulating fluidized bed. Chemical Engineering Research and Design 141, 220–228.##