流化床密相区内宽筛分颗粒气固流动研究

Study on Widely Distributed Particles Gas-Solid Flow in the Dense Phase Zone of Fluidized Bed

应用质量守恒、动量守恒等基本控制方程以及湍流、颗粒流动力学模型对流化床焙烧炉建立了宽筛分颗粒气固流动数学模型,并进行数值模拟.研究得出床层由静止启动到平稳运行过程大约需要6s;不同粒径颗粒在密相区出现分层,小于0.2mm的颗粒明显上升,易从溢流口排除;模拟分析了压强波动情况,大波动主要是颗粒团回落引起;同时模拟出了密相区颗粒流的环流和边界流.模拟结果与现场100t/d的工业流化床矿石焙烧炉上测量数据基本吻合.

A mathematical model of widely distributed particles gas-solid flow in the dense phase zone of fluidized bed(FB),based on mass conservation equation,momentum conservation equations,and turbulence model and kinetic model of granular flow,was presented.The results indicated that the bed material from stationary to steady operation required about 6 s.Particles were layered by different sizes,and particles less than 0.2 mm easily flowed out from the overflow.Pressure fluctuations were studied by modeling,and large fluctuations were mainly caused by particle clusters backflow.Circle flow and back-mixing boundary flow were modeled in the dense phase zone.Some results were validated against the data generated in a 100 t/d FB ore roasting furnace.