| To investigate the clogging of the lance during the injection of gas with or without powder, a model study on the penetration behaviour of liquid into the nozzle was carried out in water, water-glyceline mixtures, mercury and also molten pig iron. In cold models, the penetration of liquid into the nozzle was determined using an electric contact method. On the other hand, the penetration depth of the molten pig iron was measured on the lance which was cut open after the runs. A regression analysis was made to predict the relationship between the penetration depth of the liquid into the perpendicularly downward facing nozzle and the influencing factors, such as the surface tension, the densities of gas and liquid, the viscosities of gas and liquid, the inner diameter of nozzle, and the gas flow velocity. It was shown that the penetration behaviour of the liquid into the nozzle depends on the gas flow velocity, the inner diameter and orientation of nozzle, and the densities of gas and liquid. The penetration behaviour was reduced with powder injection compared to gas only injection. The comparison of results about penetration behaviour of liquid into the nozzle showed that the understanding won for cold models can be carried over to the conditions in molten pig iron. |
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