Michelle Dunn

Study of low flow rate ladle bottom gas stirring using triaxial vibration signals

Secondary steelmaking plays a great role in enhancing the quality of the final steel product. The metal quality is a function of metal bath stirring in ladles. The metal bath is often stirred by an inert gas to achieve maximum compositional and thermal uniformity throughout the melt. Ladle operators often observe the top surface phenomena, such as level of meniscus disturbance, to evaluate the status of stirring. However, this type of monitoring has significant limitations in assessing the process accurately especially at low gas flow rate bubbling. The present study investigates stirring phenomena using ladle wall triaxial vibration at a low flow rate on a steel-made laboratory model and plant scale for the case of the vacuum tank degasser. Cold model and plant data were successfully modeled by partial least-squares regression to predict the amount of stirring. In the cold model, it was found that the combined vibration signal could predict the stirring power and recirculation speed effectively in specific frequency ranges. Plant trials also revealed that there is a high structure in each data set and in the same frequency ranges at the water model. In the case of industrial data, the degree of linear relationship was strong for data taken from a single heat.

Cold model study of sound signals from gas-stirred ladles

ABSTRACT The stirring power required achieving uniform composition and temperature in ladle metallurgy is a function of the volumetric gas flow rate, metal depth, and slag thickness. Accurate estimation of the stirring power requires the precise determination of the amount of metal and slag depth. The present study found that frequencies of the acoustic signal generated during the stirring process can indicate the depths of metal depth as well as slag thickness. This is promising as it offers a potentially simple technique for simultaneously detecting slag thickness and stirring in ladles.

Application of vibration and sound signals in monitoring iron and steelmaking processes

ABSTRACT Automation of the iron and steelmaking operations is an inevitable task to improve quality and to minimise cost. Recent studies showed that vibroacoustic-based monitoring techniques can be used to continuously monitor steelmaking processes. Various signal processing techniques have been used, including filtering and FFT, to process these signals into useful inputs for process control. In ironmaking, the acoustic noise has been studied to assess working conditions. Vibration and acoustic signals have been measured in oxygen steelmaking to evaluate slopping. Lance vibration has been used to automate the blowing process at Kawasaki Steel Corporation. In ladle metallurgy, the focus has been on developing a vibroacoustic method to monitor liquid metal stirring. Recent water model studies have identified how sensor placement and the depth of the slag phase affects these signals. There has also been a work to monitor slag carry over in tundish metallurgy using vibration. These applications can be extended to other steel producing processes in the industry.

The effectiveness of resources created by students as partners in explaining the relevance of mathematics in engineering education

ABSTRACT First-year engineering students often struggle to see the relevance of theoretical mathematical concepts for their future studies and professional careers. This is an issue, as students who do not see relevance in fundamental parts of their studies may disengage from these parts and focus their efforts on other subjects they think will be more useful to them. In this study, we surveyed engineering students enrolled in a first-year mathematics subject on their perceptions of the relevance of the individual mathematical topics taught. Surveys were administered at the start of semester when some of these topics were unknown to them, and again at the end of semester when students had not only studied all these topics but also watched a set of animated videos. These videos had been produced by higher-year students to explain where they had seen applications of the mathematical concepts presented in the first year. We notice differences between the perceived relevance of topics for future study and for professional careers, with relevance to study rated higher than relevance to careers. We also find that the animations are seen as helpful in understanding the relevance of first-year mathematics. The majority of students indicated that lecturers with students as partners should work collaboratively to produce future videos.