The Effect of Bottom Nozzle Configuration on the Bath Behaviour in the BOF

Abstract

Due to the different nature of the required measurements, two separate water models were utilised. Both models have the same geometry and dimensions; scaled down to 1 : 7. The operational and geometrical parameters of the physical model and the prototype are presented in Table 1. Figure 1 shows the location of bottom nozzles for 3, 4 and 5 nozzle arrangements. The two lance positions used in splashing and oscillation studies are also displayed in the same figure. Measurement of Splashing and SpittingSplashing and spitting behaviour in the combined blown converter vessel was studied with the new method, which is previously described elsewhere in more detail. 17) Since the whole model wall is perforated, the experimental set-up enables studying overall splashing distribution on the model wall. Spitting is referred to as water droplets collected from the mouth of the converter model by an absorbent cloth. Measurement of Mixing TimeThe experimental apparatus and auxiliary instruments for ISIJ International, Vol. 44 (2004) The blowing behaviour of the BOF is affected in many ways by the behaviour of molten bath. Bottom blowing and its interaction with top blowing have a strong influence on splashing and spitting behaviour, bath homogenisation and bath oscillation. Therefore, three selected bottom nozzle configurations were studied by physical modelling, and the results were compared regarding splashing, homogenisation and oscillation of the bath. According to model tests, bottom nozzle positioning has a great influence on the amount and direction of splashing and spitting. Moreover, at lower lance gaps, the direction of splashes was changed because of bath oscillation. At low lance gap, when type A oscillation is dominant, correlation between the degree of overlap and stability of the bath was found. The bigger the degree of overlap, the more unstable the system as far as type A oscillation and splashing is concerned. The amplitude and oscillation frequency of the bath changed as a function of lance height. Blowing through bottom nozzles prevented the onset of so called type A oscillation. Bottom nozzle configuration of three nozzles resulted in shortest mixing time, lowest total splashing on model walls and longest starting time of type A oscillation.

Physical and Mathematical Modeling of Multiphase Flows in a Converter

“…The high mixing efficiency in the converter is largely attributed to stirring effects of the bottom injected gas. Therefore, the effects of various bottom nozzles conditions, [16][17][18][19]24,80,83) gas flow rates and gas supply schemes, 21,22,25,48,140) and combination schemed of top gas and bottom gas 20,26,27,30,78,79,119,141) are studied to optimize the mixing effects in the converter. The velocity distribution inside a 335-ton converter bath as well as the velocity and bubble size distribution in a six plugs 190-ton bottom blown converter with standard bottom stirring are presented in Fig.…”

“…K. Nakanishi et al 9) investigated the mixing rate of molten steel and mass transfer rate between slag and metal in Q-BOP through water model experiments. Extensive studies were also carried out on the stirring behavior andbehavior mixing characteristics in top blown, [10][11][12][13][14][15] bottom blown, [16][17][18][19][20][21][22] as well as combined blown [23][24][25][26][27][28][29] converter at different stages 30) during a heat using water models. However, the transport phenomena in steel bath are so complex that many phenomena cannot be presented by water model experiments such as the compressibility of high speed oxygen, the interaction behavior between different phases, high temperature performance, etc.…”

BOS Vessel Vibration Measurement for Foam Level Detection

“…The latter peak most likely represents the frequency of the metallic bath standing wave caused by the impingement of the oxygen jet. 16,17) …”

Influence of Bottom Tuyere Configuration on Bath Stirring in a Top and Bottom Combined Blown Converter

“…Their investigations indicated that better bath stirring could be obtained by increasing bottom nozzle eccentricity until a certain limit. Luomala et al 5) investigated the effect of three kinds of configurations of 3, 4 and 5 bottom nozzles on the bath behavior, such as splashing and spitting, bath homogenization and bath oscillation, respectively. Their results showed that configuration of three nozzles results the shortest mixing times when gas flow rate is low and pure bottom blowing results in shorter mixing times than combined blowing.…”