赤泥分离沉降槽中心桶内流体流动的水模型实验研究

Experimental study on fluid flow of red mud separation thickener feedwell

以相似原理为基础,搭建1：20比例尺的沉降槽水模型实验槽,采用有限个数颗粒示踪法,以停留时间分布（RTD）为评价指标,对沉降槽中心桶内的流体流动进行实验研究,得到稳态下中心桶内流场分布以及不同工况下中心桶内流体的停留时间分布。分别运用2种不同的非理想流动模型,并采用矩计算和非线性回归的计算方法来描述中心桶内流体流动的混合程度。研究结果表明：沉降槽中心桶内的流体呈旋转混合流动,且桶内存在流体流速相对缓慢的＂死区＂和＂短路＂的现象。流量在0.20～0.30 L/s范围时,增大流量,死区体积分数相应减少7.7%;径高比在1.60～0.75范围时,减小径高比,死区体积分数可减少15.9%,较小的死区体积有助于提升中心桶内物料混合的均匀性。沉降槽中心桶内混合程度较大,且混合程度随进料流量的增加以及中心桶径高比的减小而增大。

Based on the similarity principle, a red mud separation thickener water model was established with the geometry ratio at 1：20. Finite granules trace method and residence time distribution （RTD） were chosen as the trace method and evaluation criteria respectively. Experiments were carried out to investigate the flow patterns of the thickener feedwell as well as RTD under different operating conditions. Two different non-ideal flow models were adopted to describe flow mixing extent in the feedwell in conjunction with the moments and non-linear regression calculation techniques. The results show that the moving fluid in the feedwell can be depicted as Swirling flow. Furthermore, the stagnant areas and ＂short circuiting＂ are found in the feedwell. The volume fraction of the stagnant zone decreases by 7.7% as the inlet flow rate increases from 0.20 L/s to 0.30 L/s. When the feedwell aspect ratio decreases from 1.60 to 0.75, the volume fraction of the stagnant zone decreases by 15.9%. There exists relative large magnitude mixing movement in the feedwell, and the extent of the mixing behavior increases with the increase of inlet flow rate and the decrease of feedwell aspect ratio.