Establishment time of liquid flow in a bath agitated by bottom gas injection
- PDF / 124,522 Bytes
- 8 Pages / 612 x 792 pts (letter) Page_size
- 35 Downloads / 185 Views
INTRODUCTION
GAS injection techniques have been widely utilized in metal refining processes in steelmaking industries over the years.[1–5] Although much information has been accumulated on the bubble and liquid flow characteristics,[6] little is known about the flow establishment time in the reactors of the processes.[7,8,9] The flow establishment time is defined as the period from the start of gas injection into a still molten metal bath to the moment at which the entire molten metal flow in the bath reaches a steady state. Previous investigations of the flow establishment time[7,8,9] have been carried out, mainly for baths accompanied by swirl motion[10] such as the rotary sloshing.[11–14] The flow establishment time required for the occurrence of the swirl motion was determined using two methods: eye inspection and an electric conductivity sensor. The swirl motion took place after the flow in the bath reached a steady state.[9] Accordingly, we have to consider two kinds of flow establishment times under the occurrence of the swirl motion: flow establishment time for the liquid flow in the bath to reach a steady state and flow establishment time for the swirl motion to occur. Quantitative evaluation was done only for the latter flow establishment time, probably because the former flow establishment time was much shorter than the latter. The reason for limited knowledge about the flow establishment time in metallurgical reactors agitated by gas injection in the absence of the swirl motion can be explained as follows: The turbulence intensity in metallurgical reactors such as converters and ladles is usually very high.[15–20]
MANABU IGUCHI, Associate Professor, formerly with the Faculty of Engineering, Department of Materials Science and Processing, Osaka University, Osaka, 565 Japan, is Professor, Division of Materials Science and Engineering, Graduate School of Engineering, Hokkaido University, Hokkaido, 060 Japan. TSUNEO KONDOH, formerly Graduate Student, Department of Materials Science and Processing, Osaka University, is Engineer, Wakayama Works, Sumitomo Metal Industries, Ltd., Wakayama, 640 Japan. KEIJI NAKAJIMA is Senior Research Engineer, Corporate Research and Development Laboratories, Sumitomo Metal Industries, Ltd., Hyogo, 660 Japan. Manuscript submitted May 30, 1996. METALLURGICAL AND MATERIALS TRANSACTIONS B
Molten metal flows in these reactors seem to reach a steady state quickly due to strong turbulent mixing. Although detailed information on the establishment time for the flows in the reactors is not yet known, it has been considered to be much shorter than the operating time of actual processes. As a result, not much attention has been given to the flow establishment time. Recently, high-speed refining processes have been planned in steelmaking industries to reduce the refining time by approximately half. Evaluation of the flow establishment time is, therefore, becoming increasingly important for the development of new refining processes. As shown in Figure 1(a), the establishment time for a la
Data Loading...
