SU1461768A1 - Method of monitoring carbon content in steel-melting bath from charge-melting - Google Patents

Description

. (21) 4126464 / 23-02 (22) 09/23/86 (46) 02.28.89. Bksh. № 8

(71) Kiev Institute of Automation. XXV Congress of the CPSU, Kuznetsk metal. Lurgichesky Combine them. V. I. Lenin

(72) N.A.Fomin, V.M. Denisenko, B. B. Anisimov, L.Ya. Kolesnikov, L. D. Shevchuk, A.I. Katunin, A.E.Koshelev A.V. Zalevsky and A.V. Smirnov

(53) 681.323 (088.8)

(56) USSR Author's Certificate No. 1186646, cl. C 21 C 5/00, 1984.

, :( 54) METHOD FOR CONTROLLING THE CONTENT OF A HIGHER-LEVEL IN A STEEL-MELTING BATH BY MELTING THE CHARGE

(57) The invention relates to metallurgy and is intended to control the carbon content of a steelmaking bath. The purpose of the invention is to improve the accuracy of carbon content control of a steelmaking bath by casting steel due to a new time action associated with the measurement of process parameters. The method is based on the use of a known functional relationship between the liquidus thermal rate and carbon content for an iron-carbon solution, including determining the temperature of the liquidus based on the measurement difference of the tetrature T of the metal in the bath and the DT temperature of the technological overheating of the iron-carbon melt above the liquidus line, and measuring the temperature T „ the metal in the bath, the duration T of melting and the integral energy consumption W for melting the mixture are produced in the process of melting while integrand energy consumption Wp knowledge Cheney in the range from 0.7 to 0.9 for a period za- ./taHHoro mp. 1 il.

(L

I

The invention relates to ferrous metallurgy, in particular, to the control of technological processes of steel production, and may find application in systems for controlling steelmaking processes in, aggregates, working on solid charge, for example, in electric arc furnaces.

The aim of the invention is to improve the accuracy of carbon control.

The drawing shows the block diagram of the device for implementing the method.

The device contains blocks 1 and 2 for determining the integral energy consumption, block 3 for determining the average for the melting temperature of technological overheating of the melt above the liquidus line, block 4 for determining the crystallization temperature of the melt, blocks 5.6 for determining the temperature of corrections, block 7 for determining the temperature for liquidus, block 8 Determine the carbon content of the steelmaking bath.

K |

About 00

3,146

The method is implemented as follows.

When the integral energy consumption WP for melting the charge (blocks 1, 2) is reached, the values of 0.7-0.9 specified for the melting period are determined by the formula, the temperature of technical overheating of the melt above the liquidus line block 3):

 TO

 to.

M

U)

15

where g is the average for the period of melting, the temperature of technological overheating of the melt above the liquidus line, C,

WP - integral energy consumption for charge melting, kWh 5

M. - the mass of the charge loaded into the furnace, t;

- duration of melting

K is the proportionality coefficient, calculated in advance by processing the data set for 100-150 heats ° C. kw

Tkr T - yT.

According to the information on the temperature T of the metal, the oxygen content in the metal is also determined and the corrections of the oxidus of the metal oxidation (block 5) are calculated from the known dependencies:

25

(four)

K Hti

WP

(2)

1 Gp1o to / 6320

  2,734 - -5 ---;

IT 65 o

where QOJ is the oxygen content in 30 metal,%.

Dependencies (4) can be converted to a more convenient formula for performing practical calculations:

DT 5.72-10-2-T - 76.57. (five)

average over the mass of heats

temperature of technological overheating of the melt over the liquidus frost, C average over the mass of heats, c

melting time, h; average over the mass of heats

specific (per tonne of metal charge) energy per melt — kW-h t.

laziness charge.

Moreover, W., C, W, c refer to the segment of the melting period, which has the end, when the integral energy expenditure W is reached, in the interval O, 7-0.9, specified for the melting period.

For the operating conditions of arc furnaces ДСП-100 with water-cooled steel and the arch of the electric steel-smelting shop (ESSH) at smelting of medium-low-alloy carbon 1768

rock steel obtained K value

i 0,36

SlI, kW

According to information on the temperature T of the metal in the bath, measured during the melting process while the integral energy consumption WA reaches a value in the range of 0.7-0.9 given for the melting period, the melt crystallization temperature T is determined (block 4):

Tkr T - yT.

(3

(four)

DT 5.72-10-2-T - 76.57. (five)

The content in the initial charge of such elements as manganese, copper, nickel, chromium, phosphorus, sulfur is determined

correction for a decrease in the liquidus temperature from impurities (block 6) using known dependencies. The content of the main elements of e; in the charge is fixed by certificate. Temperature correction for a decrease in the liquidus temperature from impurities can also be determined by processing the statistical data of the melts array. For example, when processing experimental

Total data obtained during the by-smelting of carbonaceous low-alloyed yachts of steel 20X-40X under the conditions of operation of EAF-100 ESP 11: -2 HQ obtained y. T, p (4tO, 5) c.

The liquidus temperature is defined as the sum of three values — the melt crystallization temperature T, the temperature corrections to reduce the liquidus temperature due to the influence of impurities.

I uTnp and oxidation D T metal (block 7), i.e.

T +

R

ytp

+ & t,

(6)

The carbon content in the steelmaking bath is determined by the value of the liquidus temperature (block 8) using the well-known diagram Fe-C.10

The choice of the interval of values of the integral energy consumption within which the measurement of T is taken, n p is due to the melting characteristics of the charge in the steelmaking 15

bathtub. Thus, with an integral energy consumption less than 0.7 of the value specified for the period of melting, the bath is not sufficiently averaged over chemical composition, in particular over carbon, which leads 20 to an error in determining the average mass melt temperature and, consequently, to an error in controlling the carbon content.

With an integral energy expenditure of 25 more than 0.9 of the value specified for the melting period, accelerated heating of the liquid phase begins, which leads to a j K significant error in the calculation of the technological overheating temperature and, consequently, to the error in controlling the carbon content.

The most favorable conditions for measuring the temperature T of a metal in a bath in terms of ensuring better and more accurate calculation of the DT temperature of the technological overheating are conditions under which the integrated energy consumption is in the range of 0.7-0.9 o melting value.

This is due to the fact that during this melting period the bath is already sufficiently averaged by chemical composition, in particular, by carbon, which reduces the error in determining the mass-average temperature of the melt, and consequently, increases the accuracy of carbon content control.

In the same period of melting, the rate of heating 50 of the liquid phase is insignificant, since the supplied power is consumed to melt the charge, which makes it possible to more accurately calculate the DT temperature of the technological superheat, 55 and therefore increases the accuracy of carbon control.

Performing operations for measuring the temper ature Td of the metal in the bath of duration L. melting the charge and the integral energy consumption W. to melt the charge until the completion of the raiya process during the achievement of the integral energy consumption Wp in the range from 0.7 to 0.9 for the period of melting it allows to significantly improve the accuracy of controlling the carbon content in the steelmaking bath to melt the charge.

Processing the experimental data showed that the error in controlling the carbon content by the proposed methods is (0.05-0.08) abs.%, While the error in controlling the carbon content using the prototype method is (0.10-0, 25): abs.%.

The proposed method, besides having a smaller error in controlling the carbon content, makes it possible to proactively predict the carbon content of melting, which makes it possible to choose the desired process control strategy during the oxidation period.

Claims (1)

Invention Formula The method of controlling the carbon content in a steelmaking bath to melt the charge, for example, in an electric arc furnace, based on the use of the known functional dependence between the liquidus temperature and carbon content for the iron-carbon solution, which includes determining the liquidus temperature by the difference of the measured temperature Td, of metal in the bath and the DT temperature of the technological overheating of the iron-carbon melt above the liquor line, calculated from the measured values of the duration of the plaapen, integral p melting energy, mass of the charge and taking into account corrections on the effect of impurities and metal oxidation, characterized in that, in order to improve the accuracy of controlling the carbon content, the temperature T of the metal in the bath, the duration t of melting of the charge and the integral energy consumption WP on the melt, the charge is produced in the process of melting while the integral energy consumption Wp reaches a value of n in the interval from 0.7 to 0.9, specified and;)) the period of melting. I Cina / ien / iaeume b I pas bath process clause 1 sha) (you / w H-ME Tm Tm AT „ u / uj process (mnpdso / poka (o, 70, g) w ) wf msh dt; etc