细颗粒湍动流化床气固流动及混合规律的研究

HYDRODYNAMICS AND MIXING BEHAVIORS OF FINE PARTICLES IN A TURBULENT FLUIDIZED BED

在内径１９０ｍｍ、高５５００ｍｍ的流化床实验装置上，采用方便可靠的点源示踪技术测定气体的浓度分布，进而探讨气固流动特性及混合规律；依据气泡粉碎机理表征湍动流态化的基本流型结构，以揭示床中总体上的表观均一性，从而建立拟均相扩散模型，线性回归得到气体的轴向、径向扩散系数。结果表明，床中存在着明显的混合，且发现流化气速是影响混合的主要因素；模型计算表明轴向及径向扩散系数皆随气速而增大。

The gas concentration distribution in a turbulent fluided bed with 190rum inside diameter and 5500mm height was measUred by the technique of a point sourse of tracer steady-state injection in order to study the flow pattern and eding behaviors of gas-solid.Based on the mechanism of bubble-split, a pseudo homogeneous dispersion model was established to investigate the extent of gas 'ding and the change of the dispersion coefficient with gas velocity. The results indicate that the intense gas 'dxing exists in turbulent fluidized beds and the operating gas velocity is a primary factor affecting gas mixing. The calculation of the model shows that both the axial and radial dispersion coefficients of gas phase increase with increasing gas velocity.