SU1268617A1 - Method of checking present carbon content in converter bath - Google Patents

Abstract

The invention relates to the field of ferrous metallurgy, and more specifically to the control of the carbon content in a converter bath. The purpose of the invention is to increase the accuracy of control. The essence of the invention is. that after 60% of the average purge time, the current carbon oxidation rate is calculated from the contents of carbon monoxide and carbon dioxide in the exhaust converter gases and the gas consumption. In the last 40% of the purge time, the inflection point is fixed on the carbon oxidation rate trajectory and the current carbon content in the converter bath is determined by the following formula C. aj -l Vt / Q + bj, where c is the current carbon content, 7: Vf, oxidation rate carbon kg / min; Q - oxygen consumption through the tuyere; m / min; a and bj are coefficients; VC / Q Vj / Q - VC / Q is the value (L of the oxidation rate of carbon at the point of inflection on the trajectory; Q is the value of the oxygen consumption through the lance v; 1 3.p.f. ly. 3 silt J with US 2 table. a 00 Of:

Description

This invention relates to ferrous metallurgy, and more specifically to the control of carbon in a converter bath. The purpose of the invention is to improve the accuracy of monitoring the current carbon content in the converter bath. Fig. 1 is a flow chart for implementing the method; Fig. 2 illustrates the graphical dependence of the current carbon content, as a function of the magnitude of the ratio of the FIG. 3, a typical trajectory of the carbon oxidation rate. The method is carried out by means of a flowchart including a gas analyzer 1 for controlling the composition of exhaust gases and a sensor 2 for exhaust gas flow, connected to the flow adjustment unit 3 waste gas for their density, output-block 3 is connected to the first input of the unit 4 carbon oxidation rates; and the second and third inputs of unit 4, with the gas analyzer I, control the CO and 00 content in the exhaust gases, and the fourth input of the unit 4, with the purge time relay 5. The oxygen consumption sensor 6 is connected to the averaging unit 7, the output of which is connected to the dividing unit 8, and the unit 4 is connected via the averaging unit 9 to the second decoupler speed with the second input of the dividing unit 8. The second output of block 9 through block 10 of smoothing the decarburization network is connected to a storage device 11, the second input of which is connected to the output of block 8, - One output of the storage device 11 through an analyzer 12 determines the bend in the smooth decarburization rate on the path 13 the bend, and the second output of block 1 with the second input of block 13 through block 14 of subtraction, which is connected to block 8, is connected to block 15 of selection of communication, the output of which is connected to the input of block 16, determining the current content carbon. The second output of block 14 is connected to a second input of block 16, the output of which is connected to a registering device 17. In the last 40% of the average time, the converter purge duration, when the oxidation rate of carbon starts to decrease, there is a dependence of this rate on the carbon content in the metal. This relationship can be used to estimate the current carbon content if the decarburization rate is known. It has been found that the most accurate assessment of the carbon content is achieved with use. as an argument of magnitude. The dependence of carbon content on magnitude - - is essentially nonlinear. An analysis of 200 experimental heats shows that the minimum carbon dispersion relative to the regression line in the coordinates of p L Vr LC j - :: - is provided by using piecewise linear approximation, i.e., using the broken line as a trajectory. According to the experimental heats, you have an optimal number of splits (segments) equal to 20. For each straight-line segment, which is characterized by its coefficients Q-i and bj, the carbon content is estimated according to dependence. However, the minimum deviation of the calculated carbon content from the actual one is achieved by adapting the coefficients ctj and b, according to the results of previous heats. Determination of current carbon content and adaptation of coefficients; and fej is carried out as follows. Preliminarily, 20–30 melts for each J segment in the last 5–7 min (about 40% of the average total duration of the melts) of the converter purge measure the flow rates of oxygen O and the exhaust gases. , the composition of the waste basins for the content of CO, CO, Oj,,, AT ,. Calculate the decarburization rate of the metal with and determine its trajectory over time until the end of the purge. The data of the experimental heats show that the inflection point on the decarburization rate trajectory is determined by the fulfillment of the condition, Vt h -3 Vc n -2 V, c n -1, where V I is the oxidation rate of carbon in the nth dimension. Dependence (1 ) characterizes a decrease in V at four consecutive measuring points. If the condition (.1) is fulfilled, this means the occurrence of the inflection point on the US path at the moment h-3 of measurement. This point corresponds to the following fixed values of V p – Z Vo carbon oxidation rate at the inflection point of the V trajectory, Q is the oxygen consumption at V V. The data at the inflection point is used in the formula for calculating the current carbon content in the converter bath. By comparing the C values with the actual carbon content in the converter bath with the least squares method, the values of the coefficients and bj for each of the segments, which are the initial data for calculating the current carbon content in subsequent melts and adapting these coefficients based on the results of previous melts, are determined. For example, point A (FIG. 2) is correct with 0.12%, –0.5, point B - 0.07%, l - “: 0.8, point D - C 0.08%, l.– 0 , 6%. The equation of the segment AB has the VID -0.16 -, + 0.2, where -0.16, L 0.2. Such equations have all 20 segments. At the end of each heat, the actual value of carbon C falls into the area limited by the initial J segment, characterized by a certain predetermined interval in. carbon content and odds; and b; . Then, a comparison is made of the calculated value of C J with the actual carbon content of C = C, where is the limit of calculation accuracy, which is 0.1 s according to the data of the experimental heats. If in any of the areas the calculated value of C1 deviates from C by more than 0.1 s, then for this segment, the coefficients a and bj are adapted by the least squares method. For this, a regression line having a minimal variance of carbon content between three points is determined. The two points have the coordinates of the ends of the i-cuts, and the third point is the coordinates corresponding to the actual carbon content in the converter bath (point D). For example, between points A, B, D, the regression line is a segment of AB. However, as a result of the adaptation of the coefficients L and f between the segments AB and BC, a gap appears, the elimination of which is accomplished by assigning point B to the coordinates of point E, i.e. combining the beginning of the segment of the aircraft with the end of the segment AE. Studies of these experimental heats show that such a combination of segments practically does not affect the accuracy of the calculation and averages up to 0.02-0.03 s. Table 1 shows a comparison of the results of the experimental heats, where C1, C is the calculated and actual carbon content in the converter bath; d C, the deviation of the calculated C from the actual with the adaptation and without adaptation of the coefficients; N number of heats. Comparison of the data in Table 1 shows that the most accurate calculation of the current carbon content in the converter bath is achieved by adapting the coefficients o. — i. The correction of the flow of flue gases according to their density is caused by the need to bring the measurements to normal conditions. the workshops, the measured values of the oxygen consumption Q and the exhaust gases Qp .., as well as the calculated values of V for the purpose of averaging the jumps and fluctuations arising from the measurements, require averaging, which is carried out. the moving average formula is Yn, + 1 / 1X (Yj, - Yn-,), where Yr, is the measured parameter; Yj, is the average value of the measured parameter; Y |, is the average value at the previous step, n is the averaging step (6 s). Example. In the 350-ton converters, 150 experimental heats were carried out with the measurement of the composition of the exhaust gases for the content of CO, COi, OgNa, NX, Ar in the range - 100%; oxygen consumption up to 1200, consumption of exhaust gases on the pipe Bentuoy up to 1.5–10 mM of the actual carbon content at the end of the purge is within 0.04–0.3% of the purge time; the average value is 18 minutes. Consider the order of calculation for one heat. It is taken into account that the original trajectory in coordination. l Vt dinaty C - l-- obtained earlier n experienced swimming trunks and is presented in figure 2. With the start of converter flushing, the data on the composition of the CO, CO, Hj, 02 2 off-gas of the gas analyzer and the oxygen consumption values from sensor 2 enter block 3, where the corrected value of the discharge of exhaust gases is calculated from their density and the resulting value Qpj enters Decarburization rate V calculation unit 4. Additionally, block 4 receives data on the content of CO and CO in the exhaust gases and a control signal of a time delay of 11 minutes, after which the block 4 of calculation V is turned on until the end of the purge. Table 2 presents the data of measurements and calculated values every 60 s in the interval of the ISIS purge min. Table 2 measured and calculated data. For example, after 15 minutes of purging, gas analyzer 1 receives CO of 27%, COj 0.01%, O, 2.6%, H, 0.01, Nj 70.2%, Ar 0.1%, and from sensor 2 Q 1.0-10. In block 3, 0.78 U mUmin is obtained, and in block 4, the decarburization rate is V 1100 kg / min. Similar calculations are given in Table 2 for all minutes of purging. The values of V. obtained in block 4 are averaged in block 9 and are transferred to block 8 of division. The consumption data of oxygen from sensor 6 goes to block 7 by averaging further to block 8, where there is a DC So for a terminal, the ratio is 15 minutes in block 8, we have: V,. / Q 1.2. From averaging block 9, V goes to block 10, where the Vc signal is smoothed by the formula Vc (V, - VcT, -t), where Vt is the smoothed current value of the smoothed previous value; Vc is the averaged current value; 0.5 - coefficient smoothed. The signals from blocks 8 and 10 are fed into the storage device 1 1. Which records V / Q and Vj values over the last four time intervals following each other. The signal from the storage device 11 enters the analyzer 12 for determining the inflection point on the trajectory of the decarburization rate and to the block 13 data on the inflection point, where the signal from the analyzer 12 is also supplied. The next step is checking the fulfillment of the condition. V, V, V,, which indicates the presence of an inflection point on the decarburization rate trajectory. From the data of Table 2 it can be seen that the inflection point appears for 15 minutes of purging. The analyzer generates signals about the inflection point data and transmits them to the block, 13, where it is recorded; the following data: V ,. 1,100 kg / min; and Q 950 m / min and US-Q 1,2. From block 13 and 8, signals are sent to block I4, where the value of & Vc VA - is determined; --- the data of block 13; The signal from the - - block of block 14 is fed into blocks 15 and 16, in which the current carbon content C in the converter bath is calculated and the coefficients "j and bj" are adapted. Calculation C is performed after determining the inflection point until the end of the purge. During this period, all calculated values of c with a specified time interval are fed to a recording device 17. At the end of the purge (18 min), the following values were recorded: Q 1050, Qor 0.6 lO MVMHHj tc 0.08% .i.i are calculated in blocks 3 and 4 data Qg 0.45 Y m / min to 0.6, which corresponds to the coordinates of the point K. We calculate the calculation accuracy 0.02 ,, since 0.1 Cc, then we adapt the coefficients AB mt. Points A, B, C, D have coordinates A (C 0.12%, 0.5), B (C 0.07%, d 0.8), C (C 0.05%, 1.2), D (with 0.08%, uYt 0.6). The equations of the segments AB and BC have the form CC -0.16 - + 0.2, where a -o, | b,, 2; , - 0.05 + 0.11, where a-0.05, L 0.11. The least squares method between points A, B, D determines the regression line AE with minimal variance in carbon content C and actual C. Point E has coordinates E (C 0.06, 5 8). The equation of the segment AE has the form -0.2 + 0.22, where a -0.2, b 0.22, Dn bridging the gap between the segments AE and BC to point B we assign the coordinates of point E. When the coordinates of point B are changed, we obtain the equation of The EU cut, which has the form .C 0.025 X A + 0.08, where a is -0.025, b 0.08. In subsequent batches, the calculation of the current carbon content is made with new coefficients and in case of a deviation of the calculated value of carbon content from the control accuracy, the coefficients a are again adapted; and b in blocks 15 and 16 according to the proposed methodology. Experimental data from the melts show that calculating the current carbon content in the converter bath using the proposed method reduces the number of heats from 50% to 6% of the total amount requiring blowdown for the correction of carbon content, increases the durability of the lining from 570 to 700 melts and increases the yield of suitable metal for 0% Formula of the invention 1. The method of controlling the current carbon content in the converter van, which means that after a time equal to 60% of the average purge duration, the CO and CO contents in the exhaust gases, the flow of exhaust gases, and the oxygen consumption through the lance are measured. and based on these data, the current carbon oxidation rate, characterized in that, in order to improve the accuracy of monitoring the current carbon content in the converter bath, the trajectory of the carbon oxidation rate over the time at which they are fixed is additionally determined in the last 40% of the time, to increase the accuracy. the inflection point, and the current content of carbon in the converter bath is determined by the following formula LU + L: where 1C is Pge. The carbon content in the converter bath,%; V is the oxidation rate of carbon, kg / min; Q — oxygen consumption through the lance, m / min; aj Hbj-coefficients; g Q Q is the rate of oxidation of carbon at the inflection point on the trajectory of the rate of oxidation of carbon; oxygen consumption through a tuyere at Vt V. 2. The method according to p. 1, differs from the fact that. The oxidation rate of carbon in the converter bath is determined by the following formula: 0.005.36-Q - (CO + C02), where the flow of flue gases, corrected for their density, is determined by the following formula Q Qor / лГо70125 (C0 + Ni.) + O, 0196 -C0 + + 0,0143-Og + 0,001 N ;, + / + / 0,017 UAR, de. - waste gas flow, measured by sensor:; y, m / min; CO, CO.Pg - content of components in the exhaust gases,%.

Table 1

0.15

0.20 0.14 0.18 0.01 0.02 0.025 0.03

0,30,4

Vc, kg / min

While 1000 1000 I 950 T 990 G 1000 | 1050 Qlr tank kg / min t, min

0.080.060.05

0,070,070,06

0,010,010,01

0,0150,020,015

0.751,01.2

Table 2), 2-10 ,, 0. ,, 6.10 1.06-10 ,, 68., 53-10 0.45-10 1180 11901100930710640 13 14 15 16 1718

0 0.1 0.2 0.30, 0, S0,60,70,80,9 W t l FIG. g

Q.

Claims (2)

1. A method for monitoring current content of carbon in the converting bath consisting in the fact that after the time of 60% of the average 'purge duration, measured co- ^4' holding CO and C0 ₂ in the flue gases, the flue gas flow rate - oxygen through the lance. and so on. the current rate of carbon oxidation is calculated, characterized in that, in order to improve the accuracy of monitoring the current carbon content in the converter bath,. Additionally, in the last 40% of the average purge time, the trajectory of the carbon oxidation rate is determined by the time at which the inflection point is fixed, and the current carbon content in the converter bath is determined by the following formula Vc ( 1'C]. = d - + b; , I Λ g — where 1C] - the current carbon content in the converter bath,%; carbon oxidation rate, kg / min; oxygen consumption through the lance, m ^b / min; odds; V _L = Xi. QQ * Q 'the rate of carbon oxidation at the inflection point on the trajectory of the rate of carbon oxidation; consumption at SC I1>; ~ V Q * of oxygen through furVc = V *. 2. The method according to claim 1, about g l and chay with I that. the oxidation rate of the carbon dioxide in the converter bath ^ is determined by the following formula V _c = 0.005.36 · - (СО + C0 _z ), where Q ^. is the flow rate of exhaust gases adjusted by their density, determined by the following formula qL = Q _or / ^ 0.0125 · (CO + N _t ) +0.0196 00 ^ + + 0.0143 · 0ζ + 0.001 N _g + <+ ₍ О, О178 ”аГ, where Q _or is the exhaust gas flow rate measured by the sensor, m ⁴ / min ·· СО, СО _g Д1 ₂ ^ 0 ₂ , N _z Ar - content of components in the exhaust gases,%.