IMPROVING THE TEMPERATURE IN THE METAL CONVERTER AGGREGATE, WITH USING OF THE MULTI-TIERED TUYERE
Authors: Yushkevych P.O. 
Published: July 2024

The oxygen-converter method is the most common of the industrial production of steel in both Ukraine and the world. According to scientific and statistical sources, from 2017 the fate of oxygen-converting steel in the Ukraine was more than 70 % of the total steel production. To date, in the face of invasion of our sovereign state and a full-scale liberation war in Ukraine, the metallurgical enterprises operating with the oxygen converting way of obtaining steel has conditions for significant resource limitations and increasing the cost of energy, fuel resources. Therefore, there is a need for technological solutions that will increase the energy efficiency of blowing in the bath of converter without the use of external fuel resources and energy. Accordingly was developed and tested in the laboratory with physical high temperature modeling, of the tuyere with multi-tiered construction. The developed technological solution allows to organizeted blowing in the melt for help of supersonic oxygen jets through Laval’s nozzles and forming torches flame of the {CO} to {CO2}, which directly act on the surface of the melt, due to their formation with curtain sonic oxygen jets, who organizated with help of two separate groups of the cylindrical nozzles. Thanks to the video and photography and chemical selection of the melt samples, out gases from the converter and the measurement of the melt temperature, during the entire purification blowing of the melt, established the peculiarities of the conversion of the melt with using of the multi-tiered tuyere in the space of the converter bath. It is confirmed that with the use of the multi-tiered tuyere the course of converting of the melt, as with the classical multi-nozzle tuyere, consists of three main technological periods: the first — slag formation and “ignition of the melt”; the second — intense carbon oxidation; the third — getting of final chemical composition and temperature of the melt. It is established that the main difference in the use of multi-tiered tuyere lies in the more intensive begining and progress of thermodynamic, hydrogasodynamic and cerculation heating processes, along with the appearance of forming torches flame of the {CO} to {CO2} from the moment of “ignition of the melt”. Directly burning {CO} to {CO2} in a mixture of waste gases leads to a release of the large amount of heat 565 kJ/mol O2. At the same time, it should be noted that the temperature during burning {CO} to {CO2} in a mix of the waste converter gases with oxygen streams reaches up to 3000 °C in a created combustion flame torch. The predominant formation of the flame torches {CO} to {CO2} was observed after the “ignition of the melt” at the first period at the expense a lower group of cylindrical nozzles. The highest intensity of the formation of the flame torches {CO} to {CO2} was obtained in the second period at the blowing in the melt in the conditions of intense oxidation of carbon of melt, until the carbon in the melt was from 1.2 % to 0.9 % it is value of the transition concentration. Formation of the flames torches {CO} to {CO2} was be for all sonic jets from cylindrical nozzles of the lower and upper block of the blowing. At the same time, the location of the blowing blocks and the angle of inclination of the cylindrical nozzles to the vertical axis of the multi-tiered tuyere in these blocks are calculated so as to ensure the interaction of the flames torches {CO} to {CO2} with the layers of melt and transfer up to 65 % of the heat formed from flames torches {CO} to {CO2} to the melt. It is established that the use of the multi-tiered tuyere with group of Laval’s nozzles and two groups of cylindrical nozzles was use to create sonic oxygen jets, that allows increases the burning {CO} to {CO2} in the range from 29 % to 43 %, it is exceeding corresponding indicators with the use of a two-tiered tuyere in the range of 14 % to 28 %, and compared to the multi-nozzles tuyere of the classic conctruction from 24 % to 38 %. At the same initial temperature of liquid cast iron and other conditions in laboratory experiments of the high-temperature physical modeling with using a multi-tiered tuyere with group Laval’s nozzels and with two groups of cylindrical nozzles for blowing, the finaly temperature of the liquid semiproduct of the steel was higher comparatively with use classic multi-nozzles tuyere, only thanks to increasing burning {CO} to {CO2} without the use of external fuel resources and energy during blowing of the melt. Accordingly, this indicates an improvement in the energy efficiency of the converter process with helps of the multi-tiered tuyere. Bibl. 23, Fig. 4.