旋涡流化床空气动力场和气体混合试验研究

对旋涡流化床气固两相流中的气体流场和混合进行了试验研究和理论分析,探明了二次风率和喷射角对悬浮空间流场结构和回流流动的影响。用气体示踪技术首次系统地研究了旋涡流化床悬浮空间内气流横向扩散与混合的基本规律,探讨了气流结构和形态对传质过程的影响,得出了二次风射流的穿透深度和气流横向混合速率对喷射角的强烈依赖关系,研究结果表明,旋涡流化床悬浮空间喷入二次风后氧浓度的径向分布与颗粒浓度分布的规律相吻合,满足了高浓度燃料区需要高氧量的燃烧要求。

Investigation on Aerodynamical Characteristics and Gas Mixing in a Vortexing Fluidized Bed Freeboard

The aerodynamical characteristics and gas mixing were presented in freeboard of a vortexing fluidized bed (VFB) cold model. The effects of secondary air ratio and its injection angle on gas flow field and gas recirculating flow were conducted. The carbon dioxide gas was used as the tracer gas in the experiments on the lateral gas mixing and diffusion in the freeboard of VFB for the first time. Therefore, the dependence of penetration depth of the secondary air jet and the rate of gas lateral mixing on the secondary air injection angle was discovered, which is important to improve the contact and mixing between gas and solids in freeboard of a conventional FB. The experimental results also demonstrate that the radial profile of oxygen concentration with secondary air injection can match that of particle mass condition, which satisfies the combustion aerodynamic conditions of fuels.