Прогнозирование энергопотребления в период плавки шихты в дуговых сталеплавильных печах

Abstract

A solution to the problem of selecting the operating arc current at which the minimum amount of electricity is consumed for melting the furnace charge with the specified parameters of the steelmaking electric arc furnace (EAF) equivalent circuit is proposed based on the developed methods of universal and structural characteristics of the arc heat-transfer model (AHTM) is proposed. In solving the problem, the following factors were taken in consideration: the arc heat-transfer conditions in the melting space, the influence of the electrode thermal operation conditions, the influence of arc length on the heat flux structure in heating the charge by arcs, and the effect the chemical composition of working medium has on the thermophysical characteristics of the arc column plasma. The main specific feature of heating by arcs in the EAF melting space is a complex pattern of furnace charge heating due to radiation from arcs and convection as a result of plasma motion in the arc columns. The wide variation range of the ratio of the radiation power to the power transferred by convection has an effect on the furnace charge melting rate and on the amount of electricity consumed in the course of melting. The furnace charge melting intensity depends to a significant extent on the arc radiation power level. The radiation from EAF arcs was numerically analyzed with due regard to the column temperature profile using the arc universal characteristics method by solving the system of nonlinear algebraic equations of the column cylindrical model (ATHM). The arc length is calculated using the ATHM structural characteristics method and consists in comparing the arc voltage calculated from the furnace equivalent circuit equation with the arc voltage calculated using the ATHM. Knowing arc length, it is possible to calculate the arc radiation power in the EAF melting space. After calculating the arc radiation power performance characteristic and the furnace useful power characteristic according to the proposed technique, it is possible to predict the amount of electricity consumed for melting the solid furnace charge and the time of its melting with the furnace being energized. The calculated values of the solid furnace charge melting time for small- and large-capacity EAFs during their energized operation show good agreement with the experimental data. The proposed method for predicting the specific consumption of electricity for melting solid furnace charge in arc furnaces opens the possibility to select — in developing the EAC electric operation mode and in adjusting its operation---the arc operating current at which the maximum solid furnace charge melting rate is achieved and, thereby, to achieve a smaller consumption of electricity in the furnace operating cycle.