The integration of post-combustion technology in steelmaking is prominently demonstrated through the utilization of converter oxygen lances (converter post-combustion oxygen lances), RH top-blowing lances (as exemplified by the RH-KTB system), and in electric arc furnace steelmaking via secondary combustion PC guns.
This indicates that while secondary combustion technology has been effectively implemented during the molten steel blowing and refining stages, a specialized secondary combustion oxygen lance injection process technology, akin to those employed in converters or electric furnaces, has yet to be fully established in the refining stage. In this stage, the top-blowing oxygen lance is primarily utilized for forced decarburization.
Secondary combustion technology involves directing a supersonic jet from a top lance into the molten pool. Here, a portion of the oxygen reacts with carbon ([C]) in the molten steel to form carbon monoxide (CO), while another portion dissolves into the molten steel, contributing to further reactions with [C]. The rising CO then reacts with a fraction of the oxygen present in the upper region of the molten pool, undergoing secondary combustion to produce carbon dioxide (CO2) and releasing a substantial amount of heat. This generated heat is transferred to the charge or molten pool, thereby enhancing the thermal efficiency of the smelting process. In both converter and electric furnace smelting, specialized secondary combustion equipment and technologies have been developed to facilitate the oxidation reaction of CO.
In the context of RH refining furnaces, the RH-KTB method, pioneered in Japan, involves injecting oxygen at the top while allowing a portion of the rising CO to react with the oxygen within the furnace. This approach has also been partially adopted by domestic steel plants.
However, this technology has not yet fully harnessed the vast quantities of CO present in the vacuum chamber. To address this limitation, the present invention introduces specialized secondary combustion equipment and process technology tailored for RH refining furnaces. This innovation aims to elevate the secondary combustion rate in RH refining furnaces from the current 40-60% range to even higher levels, while maximizing the utilization of residual heat within the furnace to heat the molten steel. This represents a novel technological advancement for molten steel smelting in RH refining furnaces.
Technical Implementation Elements:
The primary objective of this invention is to provide an injection process that enhances the secondary combustion efficiency of RH refining furnaces and improves heat utilization efficiency within the furnace. By adopting a top blower equipped with auxiliary oxygen holes in the RH refining furnace, the post-combustion oxygen lance injection process ensures that the CO gas produced by the carbon-oxygen reaction comes into more thorough contact with the oxygen in the vacuum chamber, thereby further increasing the post-combustion rate.
When the final tapping [C] content in the converter is maintained at 0.05%, implementing the RH top-blowing oxygen injection vacuum operation process can elevate the secondary combustion rate by 20-30% compared to the traditional top lance blowing oxygen decarburization process. This results in a temperature compensation of approximately 4-6°C for the molten steel, demonstrating the significant benefits of this advanced injection process technology.
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