3.2.2. The Entrapment of Slag in Ladle with Double Porous Plugs

The entrapment of the slag in the ladle with double porous plugs was shown in Figure 7. For the water model with double porous plugs, the region between the porous plugs and the adjoining wall of the water model was signed as Region A, and the region between the two porous plugs was signed as Region B, as shown in Figure 8a. At Region A, the flow of water was similar to that of the water model with a single porous plug. However at Region B, the oil layer was pushed by the flows of counter directions from the two porous plugs, the bump of the oil layer was higher than that in the water model with a single porous plug, and the shear from the horizontal flow was stronger intensively, as shown in Figure 7. The plumes from the two porous plugs caused the vortex at Region B. So, there was oil entrapped into the vortex, which was called as vortex entrapment.

**(a) (b)** 

**Figure 7.** Entrapment in the water model at a different bottom flow rate (16 mm OLT): (**a**) Q = 0.095 m3/h; (**b**) Q = 0.191 m3/h; (**c**) Q = 0.286 m3/h; (**d**) Q = 0.381 m3/h.

**Figure 8.** The slag eyes in the water model with double porous plugs (16 mm OLT): (**a**) Q = 0.286 m3/h, (**b**) Q = 0.381 m3/h.

For the slag eye, when the bottom flow rate was small, there were two slag eyes formed at the top of the water model. When the bottom flow rate was large, the two slag eyes were merged and formed the goggle type slag eye, Figure 8. When the goggle type slag eye was formed, there was no slag floated at the Region B, Region A was the only region with slag entrapment.

Table 5 showed the areas of slag eyes at different flow rate and oil thickness. With the increase of the bottom flow rate the area of slag eyes increased for the same oil layer thickness, and with the oil layer thickness increasing the area of slag eyes decreased in the water model with double porous plugs, the trend of which was just like that in the water model with a single porous plug. Compared with Table 4, the slag eye is easier to form in the double porous plugs ladle, and the area of the slag eye is usually larger than that in a single porous plug ladle.

**Table 5.** The areas of the slag eye at a different bottom flow rate and top oil thickness in the water model with a double porous plug.


As the increase of the bottom flow rate, the entrapping depth increased in the water model with double porous plugs, shown in Figure 9, the trend of which was similar to that in the water model with a single porous plug. In the water model with double porous plugs, the critical bottom flow rate causing entrapment was 0.095 m3/h (12 m3/h for prototype ladle). Compared with Figure 6, it was found that the entrapping depth was higher obviously in the water model with double porous plugs, because there was vortex entrapment formed in Region B.

**Figure 9.** The influence of a double porous plug bottom flow rate to entrapping depth in the water model.
