Dispersion Phenomena of Bubbles and Particles in Liquid Metal Bathes at High Temperature during Injection of Them into the Bathes

由于实验困难，对高温液态金属浴中的气泡分散现象研究较少。许多研究人员试图用水和/或汞模型实验来模拟这些。但这种尝试并没有被证明是有效的。本文比较了1259°C的铜、铁液浴与水、汞液浴在室温下的分散现象，在此条件下，浴槽的几何形状和修正的弗劳德号。调整。用0.5 mmphi的石墨棒电阻率探针法测量了各浴池中气泡频率、气含率和气泡上升速度的空间分布。利用上述数据描述了气泡的分散现象，结合上述数据可估算出气泡分散区边界、槽内不同高度的气体流速和平均气泡直径。气泡频率的径向分布可以用二维高斯分布函数很好地表示。因此，气泡色散区的边界由函数的两个保持标准差来定义。水浴<汞浴<液铜浴=液铁浴的边界较宽。前两个槽的边界与气体流量无关，后两个槽的边界随着气体流量的增大而变窄。气泡上升速度的大小顺序与上列相同。利用气含率和气泡上升速度的数据，估算了槽内不同高度的气体流量，并与注气量进行了比较。在水浴中，这两个速率是一致的。在汞浴中，如果前者的速率相对于浴液中的静水压力进行修改，则两者的速率是一致的。在铜液和铁液中，前者的速率小于后者，说明注入气体的热膨胀没有完成。平均气泡直径由气泡上升速度与探头在气泡中停留时间的乘积计算得到，平均弦长为1.5。平均气泡直径的大小顺序与上列相同。结果表明，金属液浴中的气泡分散现象与水浴和汞浴中的气泡分散现象有很大的不同。调整。少

Bubble dispersion phenomena in liquid metal bathes at high temperature have not been investigated so much, because of experimental difficulties. Many investigators have tried to simulate those with water and/or mercury model experiments. But such attempts have not been shown valid. In the present work, the dispersion phenomena in liquid copper and iron bathes at 1259ﾟC are compared with those in water and mercury bathes at room temperature, under such condition that the bath geometry and modified Froude No. are adjusted.Spatial distribution of bubble frequency, gas hold-up and bubble rising velocity in each bath were measured by the electro-resistivity probe method with graphite rod of 0.5 mmphi. The bubble dispersion phenomena were described by the above data, and boundary of bubble dispersion zone, gas flow rate at different height in the bath and mean bubble diameter which could be estimated by combining the above data.Radial distribution of bubble frequency is well expressed by the … More two dimensional Gaussian distribution function. Thus, the boundary of bubble dispersion zone is defined by two hold standard deviation of the function. The boundary is wider in the order of water < mercury < liquid copper = liquid iron bathes. The boundaries of the former two bathes are independent of gas flow rate, but those in the latter two bathes get more narrow as gas flow rate increase. The bubble rising velocity is larger in the same order as above. The gas flow rate at different height in the bath is estimated with data of gas hold-up and bubble rising velocity, and compared to the gas injection rate. In water bath, the both rates accord to each other. In mercury bath, the both rates accord to each other, if the former rate is modified with respect to hydrostatic pressure in the bath. In liquid copper and iron bathes, the former rate is smaller than the latter, showing that the thermal expansion of injected gas is not completed. The mean bubble diameter is estimated by 1.5 hold mean chord length which is estimated by the product of bubble rising velocity and residential time of probe in a bubble. The mean bubble diameter is larger in the same order as above.It is concluded that the bubble dispersion phenomena in liquid metal bathes is very different from that in water and mercury bathes, even if the bath geometry and the modified Froude No. are adjusted. Less