Abstract
In the duplex steelmaking process, the oxygen flow rate is suppressed to reduce the increasing rate of the temperature in the molten bath, resulting in severe dynamic conditions. To improve the mixing effect of the molten bath, a Laval nozzle structure designed for combination gas has been proposed. In this research, five types of Laval nozzle structure have been built based on the combination gas content, and both numerical simulations and experiments are performed to analyze the flow field of the supersonic jet. The axial velocity and oxygen concentration were measured in the experiment, which agreed well with the numerically simulated data. The results show that both initial axial velocity and potential core length increase with the flow rate of combination gas. Further, applying a higher N2 flow rate could improve the oxygen utilization rate at different ambient temperatures, but this issue increases the oxygen utilization rate; however, the latter can be reduced at higher ambient temperatures.
Highlights
The duplex steelmaking process has been widely utilized to enrich valuable elements, or to remove harmful elements [1,2]
According to the operational characteristics, there are two common operational methods for the duplex steelmaking process. In traditional methods, such as the Linz–Donawitz (LD)-new refining process (NRP) and the simple bearing process (SRP) method, the hot metal is first discharged into a dephosphorization converter for producing the low phosphorus semi-steel
For the multi-refining converter (MURC) method, the liquid slag is kept inside the converter after the decarburization process and is reused in the dephosphorization process in the same converter, which decreases the slag quantity and smelting cost [5]
Summary
The duplex steelmaking process has been widely utilized to enrich valuable elements (vanadium and titanium), or to remove harmful elements (phosphorous) [1,2]. For refining the dynamic condition of the molten bath, the influences of the Laval nozzle structure, oxygen initial temperature, and injection angle on the flow field of the supersonic jet have been broadly examined by both numerical simulation and experiment, at the same conditions of the oxygen flow rate. The mixed injection method using the O2 and N2 enhances the dynamic condition in the molten bath, which further increases the vanadium extraction rate and dephosphorization rate It implies that the mixed injection method using the O2 and N2 is appropriate for the duplex steelmaking process. There are five types of Laval nozzle structures investigated, designed with different N2 flow rates Both numerical simulation and experiments are carried out to explore the influence of the N2 mixing rate on the supersonic jet behavior. The impaction area and the droplet generation rate will be reported to further discuss the impaction ability of the supersonic jet formed by the combination gas
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