Abstract
The specific power of furnace transformers of modern high-power arc steel-making furnaces has reached the value of 1.2 MVA/t and its further increase is impossible. The increased productivity is achieved through the introduction of alternative energy sources, such as: natural gas, oxygen and liquid iron. In this connection, the question arises of the rational distribution of the shares of energy resources used in the overall heat balance. One solution is to adjust the volume of each of the energy resources, depending on the stage of melting. The article considers the method, which makes it possible to judge which stage of melting the furnace is in, analyzing the value of the asymmetry coefficient of the current curve. On its basis, it is possible to build a system of automatic regulation of volumes of electricity, gas and oxygen. The coefficient of asymmetry of the current curve has a direct dependence on the magnitude of the even higher harmonic components of the arc current. The greatest value they reach at the stage of formation of wells, which decreases as the share of molten metal increases in the total weight of the furnace charge. In its turn, during melting, the value of odd higher harmonic current components increases. The control system analyzes the rate of change in the values of the even and odd harmonic components, on the basis of which it generates signals for regulating the volumes of natural gas and oxygen. The method of determining the melting stage considered in the article makes it possible to use instruments with a fairly low frequency of 500 Hz, which makes it possible to increase the overall system performance. The introduction of this system will reduce the cost of steel production and improve the efficiency of the furnace.
Keywords
Arc furnace, energy efficiency, energy distribution, the automatic control system, the asymmetry coefficient sinusoidal coefficient.
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