RU2014114402A - METHOD FOR SITING STEEL IN AN ARC FURNACE - Google Patents

Abstract

1. A method for smelting steel in an arc furnace, including the supply of metallized pellets through tubular electrodes, electric arcs in slag and metal, as well as including a computer control system for the course of electric melting, characterized in that electric arcs under the electrodes contact the liquid metal and form surfaces on it meniscus, and metallized pellets are directed through electrodes to this surface of the menisci so that the loading rate of the pellets (V, kg / s) does not exceed the rate of their melting (V, kg / s), i.e. the electrosmelting process is performed subject to the condition, kg / s, where m is the mass of the pellet, kg; N is the number of pellets on the surfaces of the menisci, pcs; τ - pellet melting time, s; - Euclidean coefficient of optimal stacking N of the number of pellets on the meniscus surface; S is the surface of the meniscus, m; S is the surface occupied by one pellet, m; r is the radius of the pellet, m, and at the same time, the speed of loading the pellets (V, kg / s) is compared with (V, kg / s) and using a computer system, the speed V is corrected according to V, which depends on the energy capacity of the furnace, i.e. subject to the condition that V≤V = [Δq / (cV) -G] / τ, where is the heat assimilation of the bath, kW; Q is the current value of the heat content of the metal slag bath in the furnace, kJ; c - heat capacity of the metal, kJ / (kg · K); G is the initial mass of metal before feeding the pellets into the bath, kg; τ - time, s; - optimal metal heating rate during electric melting, ° С / min, where Δt = 75 ± 15 ° С - optimal metal overheating over liquidus; t and t is the optimal and current temperature of the metal in the course of electric melting, ° С; [С] - concentration of carbon in liquid metal,% .2. The method according to claim 1, characterized in that, using a computer control system, S = 2π (R + L) *

Claims (5)

1. The method of steelmaking in an arc furnace, including the supply of metallized pellets through tubular electrodes, electric arcs in slag and metal, and also including a computer control system for the course of electric melting, characterized in that the electric arcs under the electrodes are in contact with liquid metal and form surfaces on it menisci, and metallized pellets through the electrodes are sent to this surface of the menisci so that the loading speed of the pellets (V _ok , kg / s) does not exceed their melting rate (V _pl , kg / s), i.e. the electric melting process is performed subject to $$V_{\mathrm{about}\mathrm{to}}\le V_{Pl}=m_{\mathrm{about}\mathrm{to}}N/{\tau }_{Pl}=\frac{m_{\mathrm{about}\mathrm{to}}}{{\tau }_{Pl}}\frac{3K{S}_{men}}{S_{\mathrm{about}\mathrm{to}}}=\frac{\mathrm{four}/3\pi r_{\mathrm{about}\mathrm{to}}^3{\rho }_{\mathrm{about}\mathrm{to}}}{{\tau }_{Pl}}\frac{0.9069*3S_{men}}{\pi r_{\mathrm{about}\mathrm{to}}^2}=\frac{\mathrm{3,6276}{S}_{men}{r}_{\mathrm{about}\mathrm{to}}{\rho }_{\mathrm{about}\mathrm{to}}}{{\tau }_{Pl}}$$

, kg / s, where m _ok - the weight of the pellet, kg; N is the number of pellets on the surfaces of the menisci, pcs .; τ _PL - pellet melting time, s; $$\mathrm{TO}=\frac{\pi }{2*\sqrt{3}}$$

- Euclidean coefficient of optimal stacking N of the number of pellets on the meniscus surface; S _men - the surface of the meniscus, m ² ; S _ok - the surface, which is one pellet, m ² ; r _c - radius pellet, m, and thus, pellets loading speed (V _c, kg / s) compared with (V _{c (e),} kg / s) and by a computer system is corrected speed V _c on V _{c (e )} , depending on the energy capacity of the furnace, i.e. subject to the condition that V _ok ≤V _{ok (e)} = [Δq _in / (with _me V _t ) -G ₀ ] / τ, where $$\Delta q_{\mathrm{at}}=\frac{Q_{\mathrm{at}}}{d\tau }$$

- heat absorption of the bath, kW; Q _in - the current value of the heat content of the slag metal bath in the furnace, kJ; with _me - the heat capacity of the metal, kJ / (kg · K); G ₀ - the initial mass of the metal before feeding the pellets into the bath, kg; τ is the time, s; $$V_t=\frac{t_{\mathrm{about}Pt}-t_{me}}{\tau }=\frac{\Delta t+\left(1539-85\left[C\right]\right)-t_{me}}{\tau }$$

- the optimal heating rate of the metal along the course of electric melting, ° C / min, where Δt = 75 ± 15 ° C is the optimal overheating of the metal above the liquidus; t _opt and t _me - optimal and current metal temperature along the course of electric melting, ° С; [C] is the concentration of carbon in the liquid metal,%. 2. The method according to p. 1, characterized in that using a computer control system calculate _Smen = 2π (R _el + L _∂ ) * _hmen and $${\tau }_{Pl}={\left({2.9782}_{r_{\mathrm{about}\mathrm{to}}}-3.7975\right)}_{{\alpha }^{\left(-0.0084r_{\mathrm{about}\mathrm{to}}-0.7868\right)}}$$

where R _el is the radius of the electrode, m; L _∂ = (U _∂ -U _a-k ) / β _u - arc length, m; _{And a U--} anodno-katodnoe voltage drop, which for electric steelmaking EAF conditions _and taken to be _U-k = 30; β _u - voltage gradient in the arc column (depending on the melting period β _u = 500-1000 V / m); $$U_{\partial }=\sqrt{U_{2f}^2-{\left(I_{\partial }{x}_E\right)}^2}-I_{\partial }{r}_{\mathrm{to}}$$

- arc voltage, V; $$U_{\mathrm{uh}f}=U_{2l}/\sqrt{3}$$

- secondary phase voltage of the transformer, V; U _2l - secondary line voltage, V; I _∂ is the arc current, Ohm; x _E = x _ke k _x - operational inductive resistance of the electric circuit, mOhm; x _KZ = 3.4 · 10 ^-3 and K _x = 1,07 ÷ 1,15 - parameters depending on the melting period; r _to = 0.4 mOhm - the active resistance of the electric circuit; x _ke = 3 * 10 ^-3 I _∂ is the depth of the arc depth, m; r _ok - the radius of the pellet, mm; $$\alpha =\frac{Nu*\lambda }{d_{\mathrm{about}\mathrm{to}}}$$

- heat transfer coefficient from the arc to the surface of the meniscus in the melting zone of the pellets, where λ = 1,1 - heat transfer coefficient, W / m · K; d _ok = 0,012 - the average diameter of metallized pellets, m; Nu = 0,194 * Re ^0,791 - Nusselt number, where Re = W * d _c / ν - Reynolds number; W = V _CO / S _in - mixing speed of the bath, m / s; V _CO is the decarburization rate of the metal during the melting period of the pellets, which, according to the results of processing the experimental melts, is 0.02% [C] / min; S _in - bath surface area, m ² ; ν is the kinematic coefficient of slag viscosity, m ² / s. 3. The method according to p. 1, characterized in that using a computer control system is calculated $$q_{\mathrm{at}}=\frac{Q_{\mathrm{at}}}{d\tau }$$

- heat absorption of the bath, kW; Q _in - the current value of the heat content of the slag metal bath in the furnace, kJ; τ is the time, s, and at the same time, the invention can be used for electric melting of steel with control of the process of continuous loading of metallized pellets in arc furnaces. 4. The method according to p. 1, characterized in that, using a computer control system, the correction of the value of V _ok V V _{ok (e) is} carried out by changing the values of N, S _men , τ _PL , Δq _in and V _t , that is, for example, if V _ok > V _{ok (e)} , then they lower the values of N, S _men , τ _pl or increase the values of Δq _in and V _t and vice versa they arrive at V _ok <V _{ok (e)} . 5. The method according to p. 1, characterized in that for calculating the parameters of steel electric melting in a computer control system, a program unit is used, which is an integral part of a computer control system for decarburization, heating and melting of pellets, briquettes and other materials in an arc furnace.