A new approach to investigate the drop size distribution in basic oxygen steelmaking
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I.
INTRODUCTION
INbasic oxygen steelmaking an oxygen jet o f high velocity impinges vertically on the molten bath to oxidize the impurities. On account of interaction between oxygen jet and molten bath large amounts of drops of varying sizes are produced.~-9These drops play an important role in enhancing the rates o f heat and mass transfer reactions. Therefore, it is important to know all the produced drop sizes and the drop size distribution. The size of drops produced due to interaction between an oxygen jet and molten pig iron has been studied by many investigators by collecting drops either outside or inside o f converterz-7 or by tilting the converter,8 or by burning a hole in the crucible.9Few investigators have also studied the drop size distribution.3"7"8 In all these methods it is not possible to collect all the drop sizes produced due to impact o f an oxygen jet because the drops are collected either far away from their place o f formation or some time after their production mechanism has been turned off. High speed films have shown that the place of formation of drops due to impact o f an oxygen jet is the jet impact area,~ and therefore the produced drops should be collected at the immediate vicinity of the jet impact area and during the persisting action o f the jet. The aim o f the present investigation is to study the drop size and the drop size distribution in basic oxygen steelmaking by employing a new approach. The basis o f this approach is the observation from the high speed films that the produced drops have a good chance to fall outside the crucible only when the vessel height is equal to bath height and when the diameter o fthe impingement zone approaches the vessel diameter.~ According to these two basic needs a hot model study was carried out. The physico-chemical behavior o fthe molten bath due to injection o f a high velocity single jet o r multi-jets has been reported previously.~0In this work the results obtained on the drop size and the drop size distribution are presented and discussed. II. SIMILARITY BETWEEN THE HOT M O D E L AND THE INDUSTRIAL SCALE LD-CONVERTERS The hot model experiments are designed by maintaining a full geometric and dynamic similarity with the industrial SATISH C. KORIA, Scientific Assistant, and KLAUS W. LANGE, Professor, are at the Institute for Ferrous Metallurgy, Technical University of Aachen, West Germany. Manuscript submittedMarch 2 9 , 1983.
METALLURGICAL
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scale converters. For the geometric similarity the ratios between the nozzle throat diameter (d,) and the bath diameter (db) and also the bath height (hb) t o bath diameter and the nozzle inclination angle are considered. The ratio o f nozzle throat diameter to bath diameter determines the distribution of jet momentum flow rate on the bath. The angle o f inclination of the nozzle axis against the lance axis o f a multihole lance determines the coalescence of the multi-nozzle jets, thereby affecting the impact area and the penetrating action of the jet. For dynamic similarity the mut
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