Abstract
Four main approaches used in controlling the thermal regime of the secondary cooling zone of a continuous machine were identified: regulation of the ratio casting speed - cooling water flow, control of secondary cooling on the basis of the surface temperature of the ingotbefore entering the SCZ and at its exit, regulation of the temperature of the ingot in each section based on the current value of the temperature of the ingot in the section, the use of mathematical models in a dynamic SCZ control. Controlling the cooling process of the ingot in the secondarycooling zone, taking into account the process of its crystallization in real time by calculating the crystallization parameters and the amount of water in the sections, is a promising area. This approach allows to optimize the water rate in the secondary cooling zone with its optimaldistribution on the surface of the ingot. An algorithm for calculating the set values of the water and air flow rates, depending on the crystallization of the ingot, which are transmitted to the automatic control system of the secondary coolling zone has been developed. Based on the proposed algorithm, software that allows to consider the current thermal state of the secondary cooling zone has been developed in an environment of object-oriented programming. In real time, the program receives the current values of the speed of drawing the ingot, the surface temperature of the ingot in front of the SCZ, the metal level in the mold. The values of static coefficients can be changed within certain limits. To verify the correctness of the calculation results, values corresponding to real production data were entered into the program.
Highlights
A scheme for splitting the checkerwork into a smaller region suitable for economic calculation is presented, but one that does not distort the physical meaning
The mathematical description in the differential equations of the physical processes occurring in the hot blast stove checkerwork in "on-gas" and "on-blast" periods
The block diagram of the program for simulating the operation of the hot blast stove group of a blast furnace is given, the subroutines included in it, their input data, basic ideas of functioning under various operating modes of an hot blast stove are described
Summary
С0 – коэффициент излучения абсолютно черного тела, Вт/(м2К); LiЗВО – длина i - й зоны вторичного охлаждения, м; LЗВО – длина ЗВО, м; vр – рабочая скорость вытягивания заготовки, м/мин; Кф – коэффициент формы поперечного сечения заготовки. Температура поверхности заготовки в начале ЗВО вычисляется следующим образом: tнач = tликв − (70 + kt hvкрр). Начало цикла вычисления толщины затвердевания и расхода воды и воздуха для каждой из секций ЗВО. Где Ln – расстояние от верха кристаллизатора до середины n-зоны, м. Толщина слоя затвердевшего металла определяется для середины в каждой зоне: ξi = k × √Кτфзi ,. Где τзi – продолжительность затвердевания заготовки в середине i - го участка, мин; k. Рассчитывается температура поверхности заготовки в середине каждой зоны: tповi = tнач − (tнач − tкЗВО) × (LLсiЗЗрВВОО)5,. Где tнач – температура поверхности по оси верхней грани заготовки в начале ЗВО, °С; tкЗВО – температура поверхности по оси верхней грани заготовки в конце ЗВО, °С; LсiЗрВО – расстояние от начала ЗВО до середины i-го участка, м.
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