Methods are proposed for intensifying mass transfer in blow of steel in a ladle using acoustic vibrations. Industrial tests of blowing metal in a ladle using a lance and imposition of acoustic vibrations generated by an external acoustic radiator are described. An acoustic blow plug (ABP) containing a resonator of jet-acoustic vibrations is proposed for argon blow of steel in the ladle. Model studies and theoretical estimates of factors that contribute to intensification of mixing and decrease in the blow plug erosion are described. The results of industrial testing of blowing steel in a furnace-ladle plant using the ABP at the Severskii Pipe Works are presented.
106Today, we may characterize metallic melts in terms of quasi crystalline structure and microheterogeneity and also in terms of disequilibrium. In a solid-liquid phase transition, the disequilibrium of the melt is asso ciated with its inheritance of heterogeneity and struc tural defects from the crystals and the activational character of change in melt structure. Solidification from nonequilibium melts results in unstable structure and properties of the final steel, according to many researchers. (For example, see [1].)In modern steel smelting, consisting of the smelt ing of a low carbon intermediate product and the sub sequent adjustment of its composition in ladle refin ing, the disequilibrium of the melt is due to intense melting processes, the addition of large masses of material for carburization and alloying, and the exten sive use of gas, liquid, and solid reagents.From research on pipe steel production by means of a superpowerful DSP 135 arc furnace, a ladle-fur nace unit, a vacuum treatment system, and a contin uous casting machine, we conclude that disequilib rium of the melt is primarily associated with decrease in plasticity of the final steel, as indicated by experi mental data (Fig. 1). The disequilibrium of the melt is estimated from the damping time of fluctuations in the kinematic viscosity (the relaxation time) in isothermal laboratory experiments. The steel samples character ized by a long relaxation time-that is, by greater dis equilibrium-are characterized by reduced relative elongation in fracture tests. In general, disequilibrium of the melt's structure is associated with defects of the cast billet.We now consider in more detail the sources of melt disequilibrium and its relationship with the properties of the final steel [2]. That provides the basis for the development and optimization of parameters for dif ferent stages of the process. SMELTINGThe oxidation of the intermediate product has the determining influence on the disequilibrium of the melt and the plasticity of the steel (Fig. 2). For stabili zation and enhancement of steel quality, the oxidation of the intermediate product should not exceed 800 ppm. Parameters characterizing the smelting of the intermediate product have been developed so as to ensure regulated oxidation by optimizing the oxygen injection and the slag conditions. To obtain oxidation in the range 500-800 ppm, the total oxygen consump tion in the melt should be no more than 3000 m 3 (Fig. 3a). Correspondingly, the FeO content in the slag should be no higher than 20-30% (Fig. 3b). ALLOYING IN THE LADLE-FURNACE UNITThe alloying of the steel has a significant influence on the disequilibrium of the melt and the performance of the solid metal. Increase in the mass of ferroalloy Abstract-Analysis shows that the disequilibrium of melts may be used to characterize metal quality and to optimize smelting technology. For the production of pipe steel by means of a superpowerful DSP 135 arc fur nace, a ladle-furnace unit, a vacuum treatment system, and a continuous casting mac...
Methods and devices that produce effective actions on different objects in the course of steel production through the use of acoustic and pulsating vibrations are considered. Data on the results of the use of blowing tuyeres, devices for cleaning blowing tuyeres, a method of generating structuro-acoustic effects in the furnace workspace, and a device for acoustic blasting of the lens of radiation pyrometers are presented.The need to increase the quality of steel has grown substantially in recent years. Ladle furnaces, vacuum furnaces, and other devices that involve argon blow of metal or blow with alternative gases have been used. Nevertheless, the studies related to learning how to increase the service life of blowdown devices and increase blow efficiency require further work. Of no little importance are questions related to dust extraction in performing this process. From this standpoint it is of interest to review the work of OAO Severskii Pipe Factory gained in joint studies with GOUVPO Ural State Technical University -UPI and OAO Dinur on the development and practical application of acoustic and pulsating devices in the production of steel. In particular, the following methods and devices have either undergone pilot-plant tests or have been in long-term use:-ladle treatment of steel with an inert gas with the use of acoustic vibrations; -application of pulsating vibrations of an argon blast ("pulsars") in blowing of metal; -a device for use in cleaning the blowing tuyeres of steel-teeming ladles;-the use of an acoustic blast method of dust precipitation in casting furnaces;-the use of acoustic vibrations to protect the lens of radiation pyrometers against becoming clogged with dust.Note that a number of other methods and devices that employ acoustic and pulsating vibrations are also at the developmental stage. LADLE TREATMENT OF STEEL WITH AN INERT GAS USING ACOUSTIC VIBRATIONSExperience gained by the OAO Severskii Pipe Factory in argon blow of steel has been previously described in detail in a number of studies [1 -9]. It was noted that a comparative analysis of the data of pilot-plant tests and trial smelting by acoustic blow has demonstrated that in terms of a number of indicators, including the number of inner and outer skins on the tubes, level of contamination of the metal with nonmetallic inclusions as well as ordinary and corrosive-active inclusions, and the content of nitrogen in the metal, trial smelting and ordinary smelting yielded roughly identical results. The content of the ordinary type of nonmetallic inclusions and of corrosion-active nonmetallic inclusions in both the trial and ordinary ladles satisfied the technological conditions. The content of oxygen in the metal in ordinary blow amounted to 9 ppm and in acoustic blow, 6.4 ppm, i.e., it fell by 28.8% in acoustic blow. The specific consumption of argon decreased slightly in acoustic blow, while the specific consumption of electiricty was reduced by 7.5%. It was also noted that after 40 smelting events with ordinary blow, the height of th...
Keywords: Modernization, steelmaking, open-hearth process, electric steelmaking, comparative energy-output ratio, dynamic energy intensity, structure of steel energy intensity, limiting factors, cost-effective use of resources.The comparative energy content of open-hearth steel with a scrap-process and electric steel in the modernization stage of electric steel smelting production is considered. The structure of steel energy content is revealed in the form of technological fuel number (TFN) and the main limiting factors of energy content are determined. A marked reduction is demonstrated for the energy content of electric steel compared with open-hearth steel. The specific nature of the carburization process for scrap is demonstrated. Typical energy content indices are revealed. The main reserves of energy resource conservation are determined.Under contemporary metallurgical plant conditions almost everywhere there is replacement of open-hearth production by electric steel melting. Important problems are resolved of increasing productivity, improvement of working conditions, and economic indices, and also a marked increase in melted metal quality. For this simultaneously with arc steel melting furnaces there is construction of devices of extra-furnace steel treatment (ladle-furnace), vacuum equipment, and steel continuous pouring machines. It is important for there to be a marked reduction in specific refractory consumption, which as is well known, during open-hearth production is extremely high. The advantages noted appear to a considerable extent in reconstruction of steel melting production in OAO Northern Pipe Plant (STZ), and during construction and introduction into operation of a new electric steel melting complex instead of the open-hearth workshop [1,2]. In the total energy resource requirement (electric power, natural gas, and fuel oil) a reduction was noted in consumption during operation of the electric steel melting workshop by a factor of 2.86 compared with that expended in the open-hearth workshop of 2.64 and 7.56 GJ/ton respectively.On this background it remains to evaluate the corresponding energy content for a whole collection of the required power and material resources with the aim of determining the main factors that affect this important index, and to estimate the potential for further energy saving during operation of a steel smelting complex. The energy content of production is acknowledged as one of the most important operating indices for engineering units, and it is the final reflection for both energy and material expenditure [3 -5]. The energy content of production is a dynamically stable engineering index, in contrast to the cost and price of production, hardly susceptible to inflation and market factors.Previously the energy content of open-hearth and electric steel has been compared [3 -5]. Proceeding from domestic practice, the technological fuel number (TFN), reflecting the production proportion of total energy content of production (minus the energy content of human labor), was ...
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