SU1678847A1 - Method of controlling metal temperature in converter - Google Patents

Abstract

The invention relates to ferrous (metallurgy, and more specifically to the control and management of steel smelting in the converter. The purpose of the invention is to increase the reliability of controlling the temperature of the metal and reduce downtime. When smelting steel in the converter, a measuring plate with a built-in thermocouple in its measuring tip, temperature recording during melting , calculations of the total amount of oxygen for smelting and the decarburization rate of the melt, as well as the supply of oxygen with a nominal consumption. After using up - 80-90% of the total The ability of oxygen to melt and achieve the decarburization rate of metal during this period, 0.1-0.3 kg / m3, reduces the oxygen consumption by 60-70% of the nominal value, determines the slag-metal boundary and sets the measuring lance below this limit by 0.5-0.9 m. Table 2.

Description

The invention relates to ferrous metallurgy, and more specifically to the control and management of steel smelting in a converter.

The purpose of the invention is to increase the reliability of temperature control and reduce downtime.

Previous melts showed that when 80-90% of the total oxygen was consumed for smelting, scrap metal practically melts. In this case, the metal heating mode is stable, and the temperature lies within acceptable limits, namely 1600-1685 ° C.

When oxygen is consumed less than 80% of the total amount of oxygen

smelting does not achieve complete melting of scrap metal, which leads to unreliable results when measuring temperature. When more than 90% of the total amount of oxygen is consumed for smelting, the probability of the metal overheating above a given temperature increases.

It was established experimentally that the greatest agreement between the actual and set metal temperatures is achieved at Vt 0.1-0.3 kg / m3. In addition, it was established at the experimental swimming trunks that the measuring tip of the tuyere should be immersed in the metal at 0.5-0.9 m relative to the slag-metal boundary. This guarantees out ofN

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measuring lance from grinding and burnout and, in general, increases the reliability of metal temperature measurement.

Experimental melts performed at which the level of the slag-metal border was fixed using an induction sensor installed in the measuring tip of the tuyere showed that

 in the final stage of smelting, if the decarburization rate is higher than 0.3 kg / m3, then the metal in this case is heavily foamed with CO bubbles and therefore the boundary is slag - the metal is strongly eroded from 1.0 to 2.5 m. This makes it difficult to install measuring

 the tuyeres are at the required level and are set on a rigid reference point, while the temperature of the metal differs from the dip point by 25 ° C. At Vc 0S1 kg / m3, the fixed temperature values significantly exceed the UT set with overheating - 15-30 ° C. This is due to the lower carbon content in the metal than the critical one, and therefore it is intense by the oxidation of iron and by the significant heat generated by the heating of the metal. In addition, in this case, the oxidation of slag and metal, significantly increases, which leads to a decrease in the quality of the meta-metal and an increase in the consumption of ferroalloys.

When the immersion depth exceeds 0.9 m relative to the slag-metal section, in 85% of cases the measuring lance swells up and requires cleaning, and its burnouts increase by 50-70%. When the measuring tip was immersed in a metal less than 0.3 m relative to the slag-metal section, in 60% of cases it was not possible to obtain an accurate temperature measurement due to slagging. measuring tip, the measurements do not match the temperature on the tumbler, measured by a barbell.

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To prevent emetalling

measuring tuyere, reducing the heat load on it and increasing the reliability of the measurement before entering it into the melt reduces the nominal oxygen consumption by 65-80%. This provides soothing baths, reducing the heat load from the reaction zone, reduces the removal of metal and improves the performance of the measuring tuyere. Reduction in fuel consumption

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than 80%, impairs the operation of the main oxygen tuyere, leads to its overheating and increases the likelihood of its burning out. Reducing the oxygen consumption by less than 65% does not provide the necessary calm of the bath and the maximum allowable conditions for its operation.

Example. Melting is carried out under the conditions of a converter shop in a converter with a capacity of 400 tons.

When 90% of the total amount of oxygen (17100 m3) is consumed, the signal from the calculation unit and the monitoring of the oxygen consumption is fed to the setpoint device, where the actual and specified costs are compared. Simultaneously from the Vt decarburization rate calculating unit, a signal arrives at the setpoint adjuster and if the decarburization rate reaches 0.2 kg / m3, a signal is generated in the setter, which is transmitted to the computational control device. The latter produces a reduction in the nominal oxygen consumption by 70% (490 m3) and gives the command to start the measuring tuyere through the actuator. When the slag-metal boundary passes through the measuring tip, a signal is received from the induction sensor to the computing and control device, which fixes the measuring lance at the level of this boundary plus 0.5 m. After that, the thermocouple built into the measuring tip and the lance are returned to the measuring tip. initial position.

Under the conditions of the converter shop, 11 experimental heats were conducted, the data of which are given in Table. 1, and 2000 heats - the data in the table. 2

The following measuring devices were used in swimming trunks: a measuring tuyere with a thermocouple type TPR-2062 of 0.25 accuracy class built into its measuring tip and

induction sensor determining the boundary between slag and metal. The measuring tip has a length of 1750 mm. The position sensor of the measuring tuyere of the selsyn type sensor is a receiver of accuracy class 1.0, a recording device of the KSP4 type, an oxygen flow integrator of the DM-358M type, the decarburization rate is calculated using the well-known formula:

Vc 0,00536-Vor (CO -i- COc): I0e,

KG / M3,

where Vpr is the waste gas flow,

m / min;

CO, CO is the content of carbon monoxide and carbon dioxide in the exhaust gases,%,

10 (2 - oxygen consumption, mee / min and total oxygen consumption for smelting is determined by the formula

Z.-L

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22l4p A, 7

G4 G)% - GcT -E | St

-

x.1000 m3

where fc f. cT is the mass of cast iron, scrap and

become)

3j - the content of the i-ro element,%;

n is the number of moles of oxygen required for oxidation (determined by stoichiometry); And 9 is the atomic weight E {, kg / atom.

The unit for oxygen consumption and decarburization rate is implemented on standard logic elements of the K553 series, and the computational control device is made on standard analog-to-digital converters of the ADC and integrated circuits of the K580 series.

Data analysis of the experimental heats at which the metal temperature is measured

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The proposed method showed that in 99% of cases, against 85% in comparison with the known method, it coincides with its measurement on the converter’s downfall and, moreover, the durability of the measuring tuyere is increased by 70-807 °.

When using the proposed method, the productivity of converters increases by 2-5% due to reduction of 10

neither heats with overburden, increase the quality of the metal by reducing its oxidation and reducing the consumption of ferroalloys by 1-3 kg per ton of steel.

Claims (1)

Formula Eteni The method of controlling the temperature of the metal in the converter, including supplying oxygen with a nominal flow rate, measuring the temperature during purging using a tuyere with a measuring sensor, calculating the total amount of oxygen for smelting and the melt decarburization rate, characterized in that in order to increase the reliability of temperature control and reduce downtime, after using up 80-90% of oxygen for smelting and reaching a decarburization rate of 0.1-0., 3 kg / m3, reduce the oxygen supply rate by 65-80% of the nominal value, dissolved metal border Galak n tuyere set measuring sensor at below the limit of 095-059 slag - netall. m t a b l I h a 716788478 table 2 PerformanceExperienced j Comparative - ----- w- - --- - - --- --7 - ------- ---- "------- Number of heats, pieces of 2000 2000 The chemical composition of cast iron,%; Carbon4.6 4.6 Silicon0.63 0 „64 Manganese 0.19 0.19 Phosphorus 0.054 0.055 Sulfur0.037 0.037 Pig iron temperature, ° С1434 1432 Consumption, t: cast iron295 295 scrap 110 110 ferroalloy3.0 3.2 lime21.3 21.5 fluorspar 0.3 0.4 Temperature Czl C1645 1648 The mass of liquid steel, t377.6 377.0 The chemical composition of steel on povalka. %: Carbon0.06 0.06 Manganese 0.12 0.12 Phosphorus 0,010 0,011 Sulfur0,022 0,023 Melting cycle, min 3775 37.4 Reliable performance of the measuring tuyere; Brem just because of zatallivani, ch12 (0.06%) 200 (10%) The number of failures due to burnout, pcs. (0.05%) 8 (0.4%) The time is simply due to burnouts, h2 (0.1%) 16 (0.8%) The number of failures of the measuring tip, pcs „4 (2.0%) 31 (15.5%) Compiled by A. Borisov Editor and "Yatsola Tehred S" Migunova Proofreader M.Samborska Order 4681 Circulation: Subscription , VNIIPI State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR 113035, Moscow, Zh-35, Raushsk iab., 4/5 (. ".." "and sec." Mb, -v "c. Production and Publishing Combine Patent 9, Uzhgorod, ul. Gagarin-, 101