Continuous Prediction Model of Carbon Content in 120 t Converter Blowing Process

A continuous prediction model of carbon content of 120 t BOF is established in this paper. Based on the three-stage decarburization theory and combined with the production process of 120 t converter, the effects of oxygen lance height and top blowing oxygen flow rate are also considered in the model. The explicit finite difference method is used to realize continuous prediction of carbon content in the converter blowing process. The model parameters such as ultimate carbon content in molten pool are calculated according to the actual data of 120 t BOF, which improves the hit rate of the model. Process verification and end-point verification for the continuous prediction model have been carried out, and the results of process verification indicate that the continuous prediction model established in the paper basically accords with the actual behavior of decarburization. Moreover, the hit ratio of the continuous prediction model reached 85% for the prediction of end-point carbon content within a tolerance of ±0.02%.

Machine Learning-Based Prediction of a BOS Reactor Performance from Operating Parameters

A machine learning-based analysis was applied to process data obtained from a Basic Oxygen Steelmaking (BOS) pilot plant. The first purpose was to identify correlations between operating parameters and reactor performance, defined as rate of decarburization (dc/dt). Correlation analysis showed, as expected a strong positive correlation between the rate of decarburization (dc/dt) and total oxygen flow. On the other hand, the decarburization rate exhibited a negative correlation with lance height. Less obviously, the decarburization rate, also showed a positive correlation with temperature of the waste gas and CO2 content in the waste gas. The second purpose was to train the pilot-plant dataset and develop a neural network based regression to predict the decarburization rate. This was used to predict the decarburization rate in a BOS furnace in an actual manufacturing plant based on lance height and total oxygen flow. The performance was satisfactory with a coefficient of determination of 0.98, confirming that the trained model can adequately predict the variation in the decarburization rate (dc/dt) within BOS reactors.

Influence of lance height and angle on the penetration depth of inclined coherent and conventional supersonic jets in electric arc furnace steelmaking

Nowadays, coherent and conventional supersonic jets are widely used in electric arc furnace (EAF)steelmaking processes. Generally, these jets are installed in the EAF oven wall with a tilt angle of 35-45?. However, limited studies have been conducted on the impact characteristics of these inclined supersonic jets. This study developed an optimized theoretical model to calculate the penetration depth of inclined coherent and conventional supersonic jets by combining theoretical modeling and numerical simulations. The computational fluid dynamics results are validated against water model experiments. A variable k is newly defined to reflect the velocity variation, which is related to the jet exit at the jet free distance. The results of the optimized theoretical model show that the lance height and lance angle influence the penetration depth of the inclined supersonic jet. At the same lance angle, the penetration depth decreases with the increase in the lance height. Similarly, it decreases with the decrease in lance angle at the same lance height. In addition, the penetration depth of an inclined coherent supersonic jet is larger than that of an inclined conventional supersonic jet under the same conditions. An optimized theoretical model can accurately predict the penetration depths of the inclined coherent and conventional supersonic jets.

Numerical Model of Dephosphorization Reaction Kinetics in Top Blown Converter Coupled with Flow Field

A 3D transient numerical model of dephosphorization kinetics coupled with flow field in a top blown converter was built. Through the model the dephosphorization reaction rate influenced by the oxygen jets and the steel flow were simulated. The results show that the dephosphorization rate at the droplet metal–slag interface is two orders of magnitude faster than that at bath metal–slag interface. When the lance oxygen pressure increases from 0.7 to 0.8 MPa, the dephosphorization rate increases notably and the end content of P has a decrease of 19 %. However, when the pressure continues rising to 0.9 MPa, the dephosphorization rate has no significant increase. In addition, the lance height shows a nearly linear relation to the end P content of steel, that the lower the height, the faster the dephosphorization rate.

Mixing Effect and Energy Efficiency Analysis for Different Lances in Steel Converter Process

The mixing effect in steel converter process is very important to the fluid flow and mass transfer in bath and directly affects the chemical reaction and temperature homogeneity in the industry steel process. The cold model was employed to research the relationship of mixing time, agitation power, lance type, operation parameters, bath shape et al. According to the results, the mixing time of the bath decreases with larger gas flow rate and bigger diameter of the bath. Increasing the nozzle inclination properly is benefit for decreasing the mixing time and improving the agitation of the bath. The relationship of mixing time and lance height is complicated, because the mixing time is fluctuant by the lance rising. By introduce the relative energy utilization factor, the agitation power utilization was analyzed and compared under different conditions. The energy efficiency is higher with larger nozzle inclination as well as the bigger ratio of diameter and depth of the bath.

Research of BOF Protection Technology by Slag Splashing

Based on the application of slag splashing for building up a protective coating layer on the refractory lining, a technique for comprehensive maintenance of converter refractory linings has been developed in this paper. The effect of slag properties, slag amount, tapping temperature, and lance height on the splashing was investigated by physical model experiments. The facilities and regimes of 50-ton converter at the Long-steel had been modified. At present, the life of converter lining has already reached to 15,000 heats, the productivity reached 87 %.

Optimization of Residual Manganese in Molten Metal in Basic Oxygen Furnace (BOF)

At the Egyptian Iron and Steel Company, attention is constantly focused on improving basic steel making practice with the aim of improvement of blowing regime and the addition of forming slag materials system. A number of factors considered important in controlling the properties of steel products and affecting the residual manganese in the basic Oxygen furnace (BOF) have been investigated by changing some industrial parameters, aiming at optimizing the residual manganese in BOF. The studied factors were manganese oxide in the slag, iron oxide in the slag, tapping temperature, Slag basicity, Lance height, blowing time, and carbon content. It was found that residual manganese increased from 0.25 to 0.35 % wt, due to the reduction of both MnO in slag from 22% to 15% and FeO from 21 to18%, also the increase of tapping temperature from 1650 oC to 1670 oC caused an increase the residual manganese from 0.27% to 0.35%, and the slag basicity decrease from 4.25 to 3.8 led to an increase in the residual manganese from 0.25 to 0.37%. Also, the change of the lance height from 1050 mm to 825 mm caused an increase in the residual manganese from 0.27 % to 0.33 %. These results are believed to be reflected on the total energy consumption and ferromanganese additions needed for producing specific grades.