The paper presents the results of the optimisation of burner nozzle diameters during the combustion of natural gas under the conditions of increasing oxygen concentrations in the oxidizer in aluminium melting processes in drum rotary furnaces. The optimisation of outlet nozzle diameters was performed employing the method of experimental measurements, the results of which can be used for aluminium melting in hearth furnaces. The measurements were carried out using an experimental upstream burner with 13.5 kW input power. The monitored oxygen concentrations in the oxidizer ranged from 21% to 50%. The measurements were performed and evaluated in two variations of the burner configuration (geometry). In the first study, the impact of the enriched oxidizer on the melting of aluminium ingots was evaluated with the defined diameter of the air nozzle, which resulted in a reduction of the aluminium charge melting time by 50% at 45.16% oxygen concentration in the oxidizer, thus achieving savings in the consumption of fuel used for melting. In the second study, the diameter was optimised depending on the combustion rate of the natural gas and oxidizer mixture. The optimisation of the nozzle parameters resulted in the reduction of the charge melting time by 23.66%, while the same 25% enriched oxidizer was used. With the rise of the enrichment level to 35%, further reduction by approximately 12% was observed. The measurement results prove considerable influence of the parameter (geometry) optimisation of the outlet nozzles and oxidizer enrichment. Appropriately selected parameters of the burner can contribute to achieving comparable results at a lower enrichment of the oxidizer. The obtained results demonstrate the intensification of the heat transfer in the current thermal aggregates. The research conclusions confirm that oxygen-enhanced combustion and modification of existing burners reduces the specific energy consumption on the process and reduces CO₂ emissions.

Air infiltration into the combustion chambers of industrial furnaces is an unwanted phenomenon causing loss of thermal efficiency, fuel consumption increase, and the subsequent increase in operating costs. In this study, a novel design for a rotary tilting furnace door with improved construction features is proposed and tested experimentally in a laboratory-scale furnace, aimed at air infiltration rate reduction by decreasing the gap width between the static furnace door and the rotating body. Temperatures in the combustion chamber and oxygen content in the dry flue gas were measured to document changes in the combustion process with the varying gap width. Volumetric flow values of infiltrating air calculated based on measured data agree well with results of numerical simulations performed in ANSYS and with the reference calculation procedure used in relevant literature. An achievable air infiltration reduction of up to 50% translates into fuel savings of around 1.79 to 12% of total natural gas consumption of the laboratory-scale furnace. The average natural gas consumption increase of around 1.6% due to air infiltration into industrial-scale furnaces can thus likewise be halved, representing fuel savings of almost 0.3 m³ per ton of charge.

Oxygen-enhanced combustion (OEC) is a useful method for improving the efficiency of thermal plants and for decreasing greenhouse gas (GHG) emissions. Basic and modified burner designs utilizing OEC in the aluminum melting process in a rotary tilting furnace were studied. A combined approach comprising experimental measurement and simulation modeling was adopted aimed at assessing GHG emissions production. Reduction of up to 60% fuel consumption of the total natural gas used in the laboratory-scale furnace was achieved. The optimal oxygen concentration in the oxidizer regarding the amount of total GHG emissions produced per charge expressed as CO₂ equivalent was 35% vol. Its further increase led only to marginal fuel savings, while the nitrogen oxide emissions increased rapidly. Using the modified burner along with OEC led to around 10% lower CO₂ emissions and around 15% lower total GHG emissions, compared to using a standard air/fuel burner. CFD simulations revealed the reasons for these observations: improved mixing patterns and more uniform temperature field. Modified burner application, moreover, enables furnace productivity to be increased by shortening the charge melting time by up to 16%. The presented findings demonstrate the feasibility of the proposed burner modification and highlight its better energy and environmental performance indicators, while indicating the optimal oxygen enrichment level in terms of GHG emissions for the OEC technology applied to aluminum melting.

The behavior of molten steel within a tundish plays a crucial role in achieving uniform temperature and chemical composition, enhancing the removal efficiency of non-metallic inclusions, and reducing the wear of refractory linings. These aspects are key for ensuring the production of steel with superior quality. In multi-strand delta-type tundishes, such as the six-strand configuration, flow dynamics become particularly challenging. Key considerations include strand-specific residence times, the uniform distribution of steel flow, and the mitigation of refractory degradation. This paper presents a detailed numerical analysis aimed at designing an optimally shaped impact pad. The effectiveness of each proposed design was assessed through a tracer-based visualization of flow behavior and the evaluation of residence time distribution (RTD) curves. RTD curves were created in isothermal conditions, while the calculations of the temperature fields of steel in the tundish were made in non-isothermal conditions. The results of the simulations were verified by a real plant trial test and indicate that the use of the “SPHERIC-K4” impact pad can greatly enhance the flow characteristics of liquid steel during the continuous casting process. These improvements include preventing the erosion of the tundish refractory lining, improving the distribution of residence times between individual casting strands, and adjusting the proportions of the mixing zones.

The long-term use of steel strip in various industries makes it an important semi-finished product, which makes it necessary to improve its chemical composition and mechanical properties, reduce its thickness and weight, expand the range of new types of steel strip and increase its production. This entails a large number of technological operations dependent on precise temperature measurement and control. In some industrial plants, the steel strip is in continuous motion, which makes the use of contact measuring devices impossible. When using non-contact measuring devices such as pyrometers or thermal imaging cameras, the emissivity of the materials being measured is a problematic parameter, as setting an incorrect emissivity value to the measuring device results in inaccurate temperature readings. The essence of this research was to establish a measurement method and to perform experimental measurements of the emissivity of a polished steel strip used in a continuous annealing line, the subsequent processing of the data from these measurements and their evaluation. The emissivity measurements were carried out for 5 types of steel strip of different parameters, while the measurement itself was carried out in the long wavelength range of 7.5–14 µm and at strip temperatures of 100–300 °C. Depending on the type of steel strip, the mean emissivity values ranged from 0.0835– to 0.1143. The emissivity of the steel strip increased with increasing strip temperature, and it was not a linear dependence. The emissivity values determined in this research could be applied to measuring equipment in actual production, which could improve the accuracy of temperature measurement in the heat treatment of polished steel strip. Thermal camera measurements in the long wavelength range, taking thermal images and their processing and determining the emissivity value of polished steel strips are the parts of this research that make it different from other already published research.