Bubble Dispersion Phenomena in Water, Mercury, Molten Iron and Molten Copper Baths

Bubble dispersion phenomena in water, mercury, molten iron and molten copper have been investigated by electro-resistivity probe method. The bath dimension and modified Froude numbers were adjusted in all measurements.Bubble dispersion phenomena were qualitatively similar both in cold model and hot metal baths. Namely, the radial distribution of bubble frequency and local gas holdup were well represented by the two dimensional Gaussian distribution function. The radial and vertical distribution of bubble rising velocity were similar in all baths. The radial distribution of mean chord length were flat at every height. The mean chord length decreased with an increase of the height from mozzle, indicating disintegration of bubbles during ascending in the bath. However, they were different quantitatively. The boundary of the bubble dispersion zone, which was quantitatively defined by the locus of twofold standard deviation of the Gaussian distribution function, was wider in high temperature metal baths than that in cold model baths. The bubble rising velocity was higher in the order of molten iron=molten copper>mercury>water bath. The mean chord length was larger in the same order as above. The thermal expansion of bubbles in high temperature metal baths were not completed until the bubbles have ascended upto 150 mm from nozzle.In conclusion, the bubble dispersion phenomena in high temperature metal baths cannot be simulated with those in cold model baths, even if the bath dimension and the modified Froude number were adjusted.