洗涤冷却室内固含率径向分布不均匀性的实验研究

Experimental research on the non-uniformity of the radial distribution of solid holdup in the scrubbing-cooling chamber

为了研究三相洗涤冷却室内固含率的径向分布特性,利用光纤探针对局部固含率进行测量,采用固含率径向不均匀指数(R_(NI)(ε_(s)))对局部固含率的径向分布不均匀性进行了定量描述。结果表明:洗涤冷却管出口以下的液池可分为气相湍动作用区、二次流动区与颗粒沉降区,其中气相湍动作用区内的气泡尾流夹带与颗粒沉降区内的颗粒间相互扰动导致其R_(NI)(ε_(s))大于二次流动区,R_(NI)(ε_(s))受到液固性质、表观气速及测量高度等多种因素的共同影响。当截面平均固含率ε_(s)相近时,二次流动区与颗粒沉降区内不同条件下的局部固含率ε_(s)的径向分布具有相似性。经非线性参数拟合得到了由无因次半径(r/R_(1))与ε_(s)表示的ε_(s)的关联式,其预测值与实验值吻合良好。

In order to study the radial distribution characteristics of the solid holdup in the three-phase scrubbing-cooling chamber,the local solid holdup was measured using an optical fiber probe,and the radial inhomogeneity of the local solid holdup distribution was quantitatively dε_(s)cribed using the radial inhomogeneity index of solid holdup R_(NI)(ε_(s)).The rε_(s)ults showed that the liquid bath below the outlet of the scrubbing-cooling tube could be divided into the gas-phase turbulent action region,the secondary flow and the particle settling region according to R_(NI)(ε_(s))value size at different axial heights.The bubble wake entrainment in the gas-phase turbulent action region and the inter-particle disturbance in the particle settling region caused R_(NI)(ε_(s))in the two regions greater than that in the secondary flow region.R_(NI)(ε_(s))was influenced by the liquid-solid properti ε_(s),superficial gas velocity and measurement height.The radial distribution of the local solid holdup ε_(s) in the secondary flow region and the particle settling zone under different conditions was similar when the cross-sectional average solid holdup ε_(s) was similar.The correlation equation ofε_(s) expr ε_(s)sed by dimensionlε_(s)s radius r/R_(1) and ε_(s) was obtained by nonlinear parameter fitting,and its predicted valuε_(s) agreed well with the experimental valuε_(s).