Characterisations of instantaneous mixing behaviours in fluidised beds with binary mixtures has many challenges. We studied the instantaneous mixing characteristics of binary mixtures in a 2-D quasi gas‒solid fluidised bed using a capacitance probe method. This method enabled the quantitative assessment of instantaneous mixing behaviours, including mixing index, rate, and time. Three kinds of binary mixtures of similar size but different density were used for the transient and steady fluidisation experiments in a bubbling fluidised bed. The mixing curves of initially segregated binary mixtures were acquired, and the instantaneous characteristics for the entire process were analysed. An equation was proposed to describe the mixing process and predict the mixing degree over time. By comparing experiments with different working conditions, the effects of superficial gas velocity and density ratio on the mixing in the centre and at the wall of the fluidised bed were addressed. During the stable fluidisation stage, the axial concentration profiles of the mixtures were obtained, and the mechanisms of mixing were discussed. Results showed that the mixing level increased logarithmically with time and eventually reached a relatively stable value. Increasing the superficial gas velocity and reducing the density ratio promoted mixing and reduced mixing time. High superficial gas velocities tended to mix the mixtures well and quickly, regardless of the density ratio of the two components.

在具有二元混合物的流化床中瞬时混合行为的表征面临许多挑战。我们使用电容探针法研究了二维准气固流化床中二元混合物的瞬时混合特性。这种方法可以定量评估瞬时混合行为，包括混合指数，速率和时间。在鼓泡流化床中进行瞬态和稳定流化实验时，使用了三种大小相似但密度不同的二元混合物。获取最初分离的二元混合物的混合曲线，并分析整个过程的瞬时特性。提出了一个方程式来描述混合过程并预测随时间的混合程度。通过比较不同工作条件下的实验，讨论了表观气体速度和密度比对流化床中心和壁处混合的影响。在稳定的流化阶段，获得了混合物的轴向浓度分布，并讨论了混合机理。结果表明，混合水平随时间呈对数增加，最终达到相对稳定的值。增加表观气体速度并降低密度比可促进混合并减少混合时间。不管两种组分的密度比如何，高的表观气体流速都倾向于使混合物充分快速地混合。获得了混合物的轴向浓度分布，并讨论了混合机理。结果表明，混合水平随时间呈对数增加，最终达到相对稳定的值。增加表观气体速度并降低密度比可促进混合并减少混合时间。不管两种组分的密度比如何，高的表观气体流速都倾向于使混合物充分快速地混合。获得了混合物的轴向浓度分布，并讨论了混合机理。结果表明，混合水平随时间呈对数增加，最终达到相对稳定的值。增加表观气体速度并降低密度比可促进混合并减少混合时间。不管两种组分的密度比如何，高的表观气体流速都倾向于使混合物充分快速地混合。