Abstract
Increase in productivity and reduction of resource and energy capacity in steel production in converters predetermine development of technological measures and improvement of design of aggregates providing preheating of scrap and other charge materials, intensification of afterburning of waste gases in working space of steelmaking unit and redox processes in liquid bath while maintaining satisfactory durability of blowing devices and lining of the converter. Using fuel-oxygen combustion flames in converter process allows solving a number of multi-purpose technological problems. Combustion of fuel in working space of converter during formation of jet or use of submerged combustion flames significantly changes hydrodynamic pattern in reaction zones and liquid bath. Thermodynamic methods have been used to determine dynamics of combustion processes of gaseous fuels and oxidation of converter bath elements during their interaction with high-temperature flame combustion products. Calculation of the process of flame interaction with chemical elements of the bath was carried out for equilibrium conditions. It was established that use of combustion flames changes composition of gas phase in working space of converter, in which H 2 and H 2 O are formed in addition to those traditionally present when oxygen is blown with O 2 , CO, and CO 2 . Presence of these gases changes thermal regime and oxidizing ability of the gas phase. When burning gas-oxygen fuel, optimal composition of initial gas mixture (natural gas + oxygen) should correspond to a ratio of 100 % CH4 + 69 % O 2 , while a vapor-gas phase containing 40 % of CO 2 and 60 % of H 2 O is formed as a product of oxidation reactions. The total enthalpy of gas-oxygen fuel combustion at converter melting temperatures with oxygen excess ratio of more than 1.0 (up to 2.0) is approximately 200 kJ/mole of the initial reagents, with methane oxidation by carbon dioxide (–7) ÷ (–14.5) KJ/mole of initial reagents) at 1800 K and the process becomes endothermic at temperatures over 2000 K (ΔH 2200 = (+7.7) ÷ (15.4) kJ/mole); with water vapor gas oxidation (ΔH 1800 – 2200 = (+19.5) ÷ (+70) kJ/mole of the initial reagents. Therefore, only when the methane is oxidized with oxygen temperature of flame can be more than 1800 K. Use of carbon dioxide, water vapor as an air oxidizer does not give necessary thermal effect.
Highlights
Improvements in bottom blowing by combined blowing technique and increase of the scrap rate // Iron and Steel Eng. 1981
Using fuel-oxygen combustion flames in converter process allows solving a number of multi-purpose technological problems
It was established that use of combustion flames changes composition of gas phase in working space of converter, in which H2 and H2O are formed in addition to those traditionally present when oxygen is blown with O2, CO, and CO2
Summary
Сгорание топлива в рабочем пространстве конвертера при формировании струи или использование погружных факелов горения значительно изменяет гидродинамическую картину в реакционных зонах и жидкой ванне. С целью повышения производительности, снижения ресурсо- и энергоемкости таких процессов должны быть созданы новые компоновки агрегатов и технологических мероприятий, обеспечивающих в том числе предварительный подогрев лома и других шихтовых материалов, интенсификацию дожигания отходящих газов в рабочем пространстве, интенсификацию окислительно-восстановительных процессов в жидкой ванне при сохранении удовлетворительной стойкости дутьевых устройств и футеровки конвертера. Сгорание топлива в рабочем пространстве при формировании струи или использование погружных факелов горения, очевидно, будет значительно изменять гидродинамическую картину в реакционных зонах и жидкой ванне. Динамика процессов горения газообразного топлива и окисления элементов в конвертерной ванне при взаимодействии с высокотемпературными продуктами сгорания факела может быть определена термодинамическими методами [19 – 21]. Для газовых смесей с высокой концентрацией СО отношение равновесия реакции контролируется константой
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