SU1520110A1 - Method of regulation of steel blowing with oxygen - Google Patents

Abstract

The invention relates to metallurgical production, in particular, to technical solutions for control and regulation associated with the processes occurring in furnaces. The aim of the invention is to reduce the oxygen consumption, reduce the heat loads on the furnace lining and electrode consumption, as well as improve the quality of the metal by increasing the accuracy of reaching the desired carbon content and reducing the carbon alloy. In order to achieve this goal, the method of controlling and regulating the steel with oxygen blowing, which consists in changing the oxygen consumption for purging by influencing the valve’s supply and the position of the tuyere by influencing its actuator, additionally measuring the current oxygen consumption for purging and current consumption carbon monoxide in the exhaust gases at the outlet of the furnace nozzle, is determined, based on the balance of oxygen consumption, the current consumption of carbon dioxide in the exhaust gases, the ratio of oxide consumption and two carbon monoxide and the current consumption of carbon in the flue gas composition, as well as the consumption of oxygen as a ratio of carbon consumption to oxygen consumption, determine the position of the tuyere, maintaining the extremum of carbon consumption and oxygen consumption for purging, maintaining the extremum maximum ratio of carbon monoxide and carbon dioxide, and stop regulating the position of the tuyere and oxygen consumption with equal obtained and specified minimum values of the degree of oxygen utilization in the blowing .

Description

The invention relates to metallurgical production, in particular to technical solutions for control and regulation associated with the processes occurring in furnaces (converter, electric steel-smelting).

The purpose of the invention is to reduce the oxygen consumption, increase the accuracy of reaching the desired carbon content in the metal, and increase the durability of the lining and furnace electrodes.

Maintaining extreme oxygen consumption, ensuring the maximum ratio of CO consumption in gases to CO consumption in exhaust gases, ensures the maintenance of optimal oxygen consumption, i.e. oxygen consumption corresponding to the maximum achievable decarburization intensity and excluding at the same time the afterburning of CO in the furnace atmosphere due to the oxygen supplied to the purge.

At some point in time, the method increases the oxygen consumption by a value selected in the tuning process (1–5% of the nominal flow rate) and at a time interval corresponding to the response of the system and also adjusted during the adjustment process (10– tOOO ml-s), estimate change in the ratio of CO consumption to CO 2 consumption.

If this ratio does not decrease, a repeat step is taken to increase the flow rate 0 and the cycle is repeated. If a decrease in the CO / CO ratio occurs, then the flow rate O decreases by one step. If, as a result of a decrease in consumption O i, an increase in the CO / CO ratio does not occur, then in the next cycle the consumption 0 increases, and so on.

The described process of monitoring the ratio of CO consumption to CO consumption and regulation of oxygen consumption depending on this ratio can be performed, for example, by an extreme regulator that maintains oxygen consumption at the maximum level, but does not lead to a decrease in the CO / CO-2 ratio.

Based on the condition that all oxygen supplied is actively involved in the reaction (which follows from the above, and neglecting (due to their low intensity) oxygen loss in oxidation reactions of other chemical elements of the bath, it can be assumed that oxygen is consumed for the formation of CO and CO.

Then, based on the chemical reaction formulas and the molecular weights of the elements, it can be calculated by knowing the charge 0 and CO, the flow rate C0, j.

О g + 2С 2СО

2CO + Oj 2COi

Molecular Weight: CO, 36; WITH 28; Oj 16; With 20.

The consumption of oxygen for the formation of C is equal to

her 2

Fo, sy,

where F-CO consumption (mass) WITH

., with

Then the oxygen consumption F for the formation of COi is

7

  FC. - F

with

5 where RD - the total consumption of oxygen (mass).

The flow rate Fcc of carbon dioxide in the exhaust gases is determined from the expression:

72

CCi

ee, il IT «T

l7 lp

from 2

sixteen

" five

five

0

0

five

0

five

Finally, the expression for determining the mass flow rate of CO takes the form:

92

FCO, 2 FO -),

and for the cost ratio of CO and CO ..Fco 14 Fcp

coGgr ;; mr -;

These calculations can be performed, for example, by a standard block of the type BVO of the AKESR system with possible internal setting of parameters and performing any computational operations,

I

The distance from the tuyere to the bath mirror has a significant effect on the intensity of the decarburization of the metal bath in the furnace, since this largely determines the nature of the interaction of the oxygen jet with the metal. In connection with constant varying conditions of purging, such as characteristics and amount of slag in the furnace, viscosity and temperature of the metal, jet pressure and others, it is impossible to determine the constant value of this distance corresponding to the optimal conditions of purging. However, it can be argued that such an optimal distance will be the distance that provides the highest rate of decarburization of the bath under other constant conditions. The decarburization rate of the bath is estimated by the amount of carbon burning out per unit time of metal from the bath, i.e. The carbon consumption in the off-gas directly characterizes the decarburization rate. Consequently, the extreme regulation made on the position of the tuyere by the amount of carbon consumption in the exhaust gases ensures the optimal location of the tuyere relative to the bath mirror during the entire course of the purge.

5, 15

At the same time, extreme regulation will allow searching for the optimal position of the tuyere as follows. At some point in time, the position of the tuyere is changed (for example, lifting) by a certain amount determined during tuning (1 to 10 mm). At a time interval determined by the response of the object and adjusted during commissioning (200-2000 ml-s), the change in carbon consumption is estimated. If the flow rate increases, the next change (step) is made in the same direction. The change in carbon consumption is reevaluated. This sequence of actions is carried out until a change in the position of the tuyere causes an increase in carbon consumption. In the absence of a change in carbon consumption as a result of the step taken or when it is reduced by the proposed method, the position of the tuyere is changed in the opposite direction to the original one and 1;

Determination of carbon consumption Fj. exhaust gases are produced at FCU and FCO flow rates in accordance with the molecular weight values of chemical elements:

FC 36

28

-f

with

g - with - as the purge progresses and the carbon content in the metal bath decreases, the decarburization intensity decreases. This leads to a gradual decrease in the use of oxygen supplied to the purge, which is boosted by the ratio of carbon consumption in the exhaust gases to the oxygen consumption supplied to the purge. Under conditions of self-tuning of the parameters of purging to the actual conditions of its performance, envisaged by the proposed method, the degree of use of oxygen and the carbon content in the bath become sufficiently correlated values. Consequently, the magnitude of the degree of use of oxygen can be judged, at a constant technological process, about the content of carbon in the metal. In other words, it becomes possible for the same smelting process.

-

. . 2 25

106

began to finish blowing at a predetermined, experimentally found value of the degree of use of oxygen corresponding to the required carbon content, and the carbon content in the metal was fairly stable.

Oxygen utilization rate

2

Fo

K (5 is determined by the formula:

Ko

0

thirty

35

40

45

50

55

When the KQ value is exceeded (the specified minimum value) of K, the oxygen supply and lance movement stop.

Thus, the proposed method provides for the operative control of the carbon monoxide consumption in the flue gases, the flow rate supplied to the oxygen purge, the carbon dioxide consumption in the flue gases, the carbon consumption in the flue gases, which is part of CO and CO, and the regulation of the purge intensity (current oxygen consumption for purging) according to the criterion of achieving the maximum value of the ratio - and the position of the I-g with 7

tuyeres by the criterion of achieving the maximum FC value. When these conditions are met, an optimum amount of oxygen is supplied to the furnace at the optimum location of the tuyere, which ensures a high rate of metal decarburization during the entire purging process with minimal oxygen consumption throughout its entire process. At the same time, a minimal thermal effect on the lining and electrodes was achieved, which, together with a decrease in the oxygen and carbon dioxide concentration in the furnace atmosphere, reduces the consumption of electrodes and increases the durability of the lining.

The optimal supply of oxygen to the furnace and the timely end of the blowdown reduce the burning of the metals doped from the bath and eliminate the excess oxygen consumption. The purge time is reduced by reducing the likelihood of cases of gross errors in determining the end time of the purge and conducting subsequent blowers.

. To eliminate the disturbance of the oxygen consumption control loops and the position of the tuyere, the time required for adjusting the contours (speed) must be different.

For example, the adjustment time of the lance position contour should be less than the time of the oxygen consumption adjustment contour, so that the lance has an optimum position during the adjustment of the oxygen consumption.

The most effective application of the proposed method is the control and regulation of steel with an oxygen purge in combination with an argon-oxygen purge involving the supply of oxygen in a mixture with argon, and their total consumption is kept constant, which stabilizes the kinetic processes of interaction of the purge jet with the metal bath and allows it to change oxidizing ability.

Claims (1)

Formula invented The method of regulating the blowing of steel with oxygen mainly in an arc furnace, which consists in changing the oxygen consumption for blowing and position of the tuyere, characterized in that, in order to reduce Neither the oxygen consumption, the accuracy of reaching the required carbon content in the metal, the increase in the durability of the furnace lining and electrodes, additionally measure the current consumption of oxygen for blowing and the current consumption of carbon monoxide in the exhaust gases at the outlet of the furnace nozzle, it is determined from the balance of oxygen consumption, the current consumption of carbon dioxide in the exhaust gases, the ratio of the consumption of carbon monoxide and carbon dioxide and the consumption of oxide and carbon dioxide two-carbon dioxide — the current consumption of carbon in the composition of the exhaust gases, as well as combines the degree of oxygen use as a ratio of carbon consumption to oxygen consumption, changes the position of the tuyere, maintains an extreme maximum of carbon consumption, and oxygen consumption for blowing, maintains an extreme maximum of the oxide-carbon dioxide ratio, and stops adjusting the position of the tuyere and oxygen consumption when the output is equal and the minimum degree of oxygen utilization per purge specified by the technology.