Steel-melting Furnaces Research Articles

Effect of the secondary current lead resistances on the properties of an arc steel-melting furnace as a receiver and transformer of electric power

The effect of the resistances of secondary current leads on the electrotechnical characteristics of an arc steel-melting furnace and heat regimes is considered.

Evaporation of iron during steelmaking in arc furnaces

The problems of iron evaporation during steelmaking in an arc steel-melting furnace are considered. A procedure is developed for the calculation of the specific iron evaporation rate and the heat losses during evaporation. More complete absorption of the heat of condensation by a charge and the oxidation of iron vapors are shown to be promoted by the following factors: the presence of a slag coating, a decrease in the well diameter, an increase in the well depth, an increase in the electrode failure diameter, and directional supply of an oxidizer to the near-electrode zone.

Promising trends in improving steelmaking and finishing in ac electric arc furnaces and ladle-furnace units

The results of laboratory and full-scale tests performed to reveal the factors that affect the appearance of a constant arc voltage component (CAVC) in an arc steel-melting furnace (ASF) and an ladle-furnace unit (LFU) are presented.

Rational position of a plasmatron and energy saving in a plasma-arc steel-melting furnace

The rational position of a plasmatron in a plasma-arc steel-melting furnace is studied analytically. The rational position by the end of melting of a charge and after its melting is found to be the position of a plasmatron at an angle of 70 °–75 ° to the vertical axis. As compared to the roof position of the plasmatron, this position increases arc radiation onto the metal pool and the arc efficiency increases by 40–60%.

СТОХАСТИЧНЕ ПЛАНУВАННЯ ЕКСПЕРИМЕНТУ В ЗАВДАННЯХ ЙМОВіРНіСНОГО КОМП’ЮТЕРНОГО УПРАВЛіННЯ ПРОЦЕСАМИ РЕГУЛЮВАННЯ КООРДИНАТ В ЕЛЕКТРОМЕТАЛУРГії

The dynamic functioning of computer stochastic system of imitating coordinates regulation of furnace electro technological complex on the basis of arch steel melting furnaces theoretical and mathematical research is carried out. Dispersive analysis of outer factors is made according «Dneprospecstal» factory complex, which acts on the basis of regulating action component, cluster and dynamic synthesis models.

Rational methods for the intensification of melting in modern arc steel-melting furnaces

1 The progress in the development of electrical engineering, machine building, refractories, and electrodes and the appearance of water-cooled wall panels and roofs allowed steelmaking to be jumpwise intensified in the last quarter of the twentieth century as a result of the wide application of ultrahigh-power arc furnaces and the related modern technology of melting using alternative energy sources. The technical and economic indices of electric melting continue to increase. However, the following problems are still challenging: the maximum increase in the arc furnace capacity at relatively low additional capital outlays and a decrease in the heat loads induced by a powerful electric arc on a furnace lining via an increase in the consumption of the energy from alternative sources and via a decrease in the electric energy consumed for a heat. The following methods of heat intensification are used both separately and jointly in modern electric furnace steelmaking:

Autocorrelation functions of current of an arc steel-melting furnace at various technological stages

Basic coefficients that characterize the autocorrelation functions of a stochastic current in a DSP-40 arc steel-melting furnace (ASMF) are obtained for all the heat technological stages. A stable exponential-cosine autocorrelation function of the arc current in the DSP-40 was revealed for all the technological stages over a wide range of varying the coefficients α and ω0. The autocorrelation function of arc current variations in the DSP-40 is shown to be determined mainly by the parameters of the used automatic power controller of DSP-40.

Effect of Melting Temperature on the Wear Characteristics of Austenitic Manganese Steel

The practice in most manganese steel melting furnace is to raise the melting and pouring temperatures to 1500℃ and above so as to enhance fluidity of the molten metal and ease removal of slag. High temperature promotes micro and macro carbide segregation of alloy elements and formation of embritting transformation products. The presence of segregation at the grain boundaries, acts as barrier to dislocation movement. This could be responsible for uneven, inconsistent wear rate and pattern of the steel. This paper studies the effect of pouring/melting temperature on the propensity of carbide segregation of austenitic manganese steel and by translation on the wear characteristics of jaw crushers. Austenitic manganese steel (AMS) was subjected to different heat/melt temperatures ranging from 1380 to 1550℃ (H1-H3) in an induction furnace of 1-ton capacity. Samples obtained from the edge, middle and mounting section of the heat treated steel were examined by means of optical metallurgical microscope and the relative abundance of elements was determined by means of energy dispersed X-ray (EDX) elemental spectrometer. The results indicated high segregation of alloy elements at high melting temperatures. However, uniform dispersion of carbide particles in the base of the austenitic grains was noticed at pouring temperature range of 1400-1500℃.

Use of magnesian-dolomite mixtures in steel-melting furnace hearths and the mechanism of their wear in service. 1. Study of Jehearth refractory mixture

Use of magnesian-dolomite mixtures in steel-melting furnace hearths and the mechanism of their wear in service. 1. Study of Jehearth refractory mixture

Use of magnesian-dolomite mixtures in steel-melting furnace hearths and the mechanism of their wear in service. 1. Study of Ankerharth refractories

The results of mineralogical-petrographic analysis of Ankerharth magnesian-dolomite refractory mixtures used in the hearths of steel-melting furnaces are described. The regularities of changes in their phase and chemical compositions are identified and the mechanism of their wear in service at the Omutninskii Metallurgical Works is considered.

Variational method for solving radiative transfer problems

The variational principle is used to solve two problems of radiative transfer. The first one is the temperature distribution and radiative heat flux for a plane layer of ceramic material. While the second is the calculation of the integral blankness degree of a sphere filled with dust of an arc steel-melting furnace. Numerical results obtained shows good agreement with the published data.

Ejection of steel and slag droplets from gas stirred steel melts

Liquid ejections from gas stirred melts can be classified into small film and jet droplets caused by bubble bursting and larger splashes resulting from gas channels formed at higher exiting gas velocities. In view of the conditions in ladle metallurgy, experimental investigations were carried out at moderate to low gas flowrates in an arc heated, bottom stirred 150 kg steel melting furnace and an 80 L water tank. Droplets were collected at different heights above the melt level, while gas flowrates, viscosities, surface tensions, and slag layer thickness were varied. The number of steel droplets collected decreased greatly with height (in the range 30-110 mm) and with size (in the range 0·1-1·8 mm). Calculations showed that the entrainment of droplets is strongly influenced by the velocity of upward flowing gases. While at low flowrates typical for secondary metallurgy (0·1 m s -1), only droplets <50 μm will be entrained, BOF (basic oxygen furnace) typical flowrates (20-50 m s -1) will cause particles up to 500 μm to be carried into the dust removal systems. Higher surface tensions resulted in increased droplet ejection, while higher viscosities led to a decreasing quantity of ejected melt. Slag layers led to a decrease in the ejection of steel droplets and to an increase in ejected slag but they did not completely stop steel ejection, because gas bubbles appear to entrain steel drops when they rise through the slag layer. Bubble bursting in a pure slag system caused large but few slag droplets due to the high viscosity of the slag as compared to the steel melt.

A NUMERICAL STUDY OF JETS IN A REACTING CROSSFLOW

This article is concerned with computational modeling of the mixing of circumferentially placed round jets with a crossflow in a circular duct. This flow is relevant to many engineering applications including gas turbines and steel melting furnaces. Both nonreacting and reacting flows are considered. The fundamental characteristics that govern the mixing of the air and fuel streams are investigated. Further, the applicability of a laminar flamelet model for prediction of the combustion process is assessed through comparison of code predictions to experimental data.

First in CIS systems of metal bottom purging by inert gases in arc steel-melting furnace

First in CIS systems of metal bottom purging by inert gases in arc steel-melting furnace

The Combustion Efficiency of Furnace Exhaust Gas Combustors: a Study of Jet Mixing in a Reacting Cross-Flow

Flame length and CO measurements have been conducted on different geometrical configurations issuing air through the circumferential openings in a reacting cross-flow. The main application of the research is to improve the understanding of jet mixing in a reacting cross-flow in order to optimize the design of combustors used to destroy combustible exhaust gases from steel-melting furnaces. Current combustor designs are characterized by poor mixing with the combustion air entering through a gap (circumferential slit), deflecting the main flow and slowly mixing via turbulent diffusion. Alternate air inlet geometries have been studied by investigating the mixing of various circumferential air jets configurations into a high temperature combusting cross-flow. The experimental results show that the flame length decreases with increasing jet mass flow. The carbon monoxide combustion efficiency does not follow the same trend. All configurations exhibit optimum combustion efficiency at the momentum flux ratio that corresponds to the non-reacting optimum mixing conditions. Jet configurations with higher design momentum flux ratios have improved combustion efficiencies. These results suggest that furnace exhaust gas combustor designs that follow the non-reacting optimum mixing design equations have optimal CO combustion efficiencies.

AC-DC converter with parametric reactive power compensation

Resonant converters of 50 (60) Hz AC-DC are described, where each half cycle of network voltage the capacitor and inductor of an oscillatory circuit are switched from series into parallel and vice versa. The duration of series and parallel connection and also the transformer ratio are parametrically dependent on load. In the case of short circuit, only the parallel oscillating circuit operates. This restricts sharply the output current. The reactive power of the capacitor and the inductor compensate each other, both in the cases of series and parallel connection. Therefore, the power factor is very high from no load to short circuit. This converter fits very well for supplying arc furnaces, and there is no need for the costly and fast reactive power compensator and filter circuits. The operating principle of the converter, design principles, and a real operating converter rated 5.4 MW supplying a steel-melting arc furnace are described.

Unfired periclase-carbon refractories on a phenol binder

Periclase-carbon refractories on a phenol-formaldehyde binder developed in a laboratory are described. The pilot batch produced by the Magnezit JSC exhibited high properties. When tested in the lining of arc steel-melting furnaces the refractories had a twice as high service life as that of fired periclase articles. Deep blasting of tanks of open-hearth furnaces revealed the same endurance as that of high-quality fired articles fabricated from a molten material.

Tests of mullite-corundum refractories based on fused mullite in the roof of an electric steel-melting furnace

Mullite-corundum refractories based on 63 – 90% fused mullite have been produced and tested in the roof of a 50-ton electric arc furnace. It has been established that their wear resistance is no worse than that of heat-resistant mullite-corundum bricks of grade MK-80 produced according to TU 14-80405-82. The tested refractories were worn due to their saturation with oxides from the molten products and the interaction of the latter with the structural components of the refractory. This promoted the decomposition of mullite into corundum and a glass phase with aftercompaction ands spalling of the refractory.

Slag resistance of refractories in the lining of an arc steel melting furnace

The interaction of refractories of various grades with liquid slags whose samples were taken in different stages of melting from an electric furnace are investigated by wetting for temperatures ranging from 20 to 1550°C. The compositions of the slags differed in the CaO/SiO2 proportion and the content of chromium oxide. It has been established that the olivinite refractory has advantages under the conditions of electric melting, which seems to be explainable by its chemical composition and specific pore structure. The results of the investigation were used to develop compositions of gunite powders for torch guniting of linings of the slag belt of an arc steel melting furnace.

New solutions in lining of domestic electric arc steel melting furnaces

New solutions in lining of domestic electric arc steel melting furnaces