# Influence of Burner Nozzle Parameters Analysis on the Aluminium Melting Process
###### Abstract  
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 CO\({}_{2}\) emissions. oxygen enhanced combustion; burner; heat transfer; melting of the aluminium; thermal efficiency; air nozzle; experimental device; optimisation +
Footnote †: journal: Applied Physics Letters  
_Applied Physics Letters_
of thermal aggregates used for secondary aluminium production [3]. Based on their design, rotary furnaces can be divided into drum rotary furnaces and tilting rotary furnaces, which are described in more detail in [4; 5; 6]. Global energy and environment policies push manufacturers towards increasing the thermal efficiency of thermal equipment while reducing emissions from technological processes. The current trend in the operation of these types of thermal aggregates is air-fuel combustion, in which fuel is combusted with oxygen-enriched air or oxy-fuel combustion. The authors of those publications agree that an important factor in aluminium melting processes characterised by increased oxygen concentrations is represented by the increase of combustion temperatures in the furnace work area (see [7; 8; 9; 10; 11; 12; 13]). From the viewpoint of using oxygen during the aluminium melting process, an optimum level of oxygen enrichment for the oxidizer must be determined. This issue is well addressed by [PERSON] [10] and [PERSON] [9]. In his study related to the use of oxygen, [PERSON] [10] presented an optimized type of the burner known under the commercial name RAPIDFIRETM, manufactured by Air products. This burner type is a combination of an oxy-fuel burner and an air-fuel burner. This construction variant provided a high flexibility in firing gas and was specially designed for aluminium smelters. According to the results of this study, the replacement of the air-fuel burner with the RAPIDFIRE burner resulted in the increase of the furnace productivity by 31% and fuel savings reached 36% at 80% oxygen enrichment of the combustion air. In their study, [PERSON] et al.