KR101663949B1

KR101663949B1 - Blowing method of converter

Info

Publication number: KR101663949B1
Application number: KR1020150099783A
Authority: KR
Inventors: 유철종
Original assignee: 주식회사 포스코
Priority date: 2015-07-14
Filing date: 2015-07-14
Publication date: 2016-10-12

Abstract

In the present invention, the amount of decarburization oxygen involved in the decarburization reaction is accurately calculated after ignition at the time of transferring, and on the basis of this, the amount of decarburization oxygen participated in the decarburization reaction is calculated from the total required amount of heat, The present invention relates to a method of operating a normal converter for supplying and subtracting a required amount of oxygen subtracted per unit time, preferably an equal amount, and for producing a normal molten steel.

Description

Blowing method of converter

More particularly, the present invention relates to a method for accurately determining the amount of decarburization oxygen involved in a decarburization reaction after ignition of a converter, and based on this, The required amount of oxygen, which is subtracted from the amount of decarburization oxygen involved in the decarburization reaction, is supplied in an amount, preferably an equilibrium amount, divided into unit times per unit time, so that normal converter operation and normal molten steel production are possible And a method of blowing.

In the converter method, oxygen is blown into molten iron to produce molten steel by oxidizing and refining while maintaining thermal balance using heat of oxidation reaction of carbon, silicon, phosphorus, and the like.

In general, scrap iron and molten iron are charged in the converter, and oxygen is supplied through the lance at the top to burn off carbon, which is an impurity in the molten iron, and remove the remaining silicon, manganese, phosphorus, sulfur and other elements with slag Molten steel is produced from molten iron. At this time, the flue gas generated by reaction with the carbon in the charcoal is sucked into the hood by the negative pressure generated by the rotation of the fan, and the flue gas is heated to a high temperature by the reaction of carbon and / or other elements with oxygen If the system is set so that an appropriate negative pressure is formed during operation so that the exhaust gas generated inside the converter does not flow out of the converter in the hood, the speed of the fan is controlled in consideration of oxygen flow rate, . If the pressure inside the hood is formed at a positive pressure rather than a negative pressure, the flue gas is blown out of the converter, the flame burns the surrounding equipment and air pollution occurs. On the contrary, if too low a negative pressure is formed, Is sucked into the converter and the hood to increase the amount of exhaust gas, the load is instantaneously applied to the fan, so it is required to adjust to a proper negative pressure.

Further, in order to increase the production amount of molten steel of excellent quality, it is required to carry out the casting process so that the carbon in the cast iron remains in an appropriate amount, and the casting process is mainly performed by removing the carbon in the casting iron through oxidation reaction with oxygen It is very important to properly control the oxygen supply in the entire curing process.

The blowing process is performed by supplying oxygen from the initial ignition of the blowing, and achieving an appropriate amount of decarbonization (the amount of carbon removed from the molten iron by the oxygen) is achieved and then the blowing is stopped (oxygen blowing is stopped) Considering the content and amount of other elements including carbon in the charcoal used as the parameters, the composition and amount of scrap used, and the composition and usage amount of other raw materials such as quicklime, fluorite, light dolomite and ferrosilicon, The supply amount of oxygen per unit time is controlled so that the optimum heat mixing rate is achieved based on the temperature change depending on the carbon content in the molten iron, Control is required. Here, ignition means that the carbon in the molten iron is oxidized by the oxygen supplied through the lance and the oxidation reaction for releasing the reaction heat is continued. Particularly, in the curing process, control of the oxygen supply amount before ignition and after ignition is very important. That is, when too much oxygen is temporarily injected into the converter before the ignition is performed, the explosive reaction occurs instantaneously with the carbon in the charcoal so that the contents in the converter including the charcoal are spouted and scattered, , And if too little oxygen is supplied, ignition may not occur well. Further, it is also required to supply a sufficient amount of the required amount of air for performing the proper air-blowing in the air-blown after air-blowing, and the adequate amount of air means to supply a proper amount of air to perform the blowing process. It can be defined as the oxygen supply per minute.

However, there may be the following problems when this is performed in the actual curing process. That is, when the lance comes down to the inside of the converter and the operator confirms the nose at the ignition point where the supplied oxygen and the carbon in the molten iron meet, the normal kneading process is performed, and the oxygen amount supplied after the ignition is accurately inputted It is possible to produce molten steel having a carbon content which is required to be inputted through the welding operation. However, even in the judgment of the ignition point, the workers judge whether the ignition is ignited by naked eyes and press the ignition button accordingly, There is a possibility that individual differences may occur and that workers may delay the ignition timing and press the ignition button late so that the normal knocking may start late or the ignition may not be performed. To accurately measure the amount of oxygen supplied later It is difficult, therefore there may be a problem that would be difficult for the production of molten steel with a predetermined carbon content. Further, when the ignition is recognized as a non-ignition state even in the already ignited state, since the speed of the fan for forming the negative pressure for exhaust is constant, the hood is not controlled to an appropriate pressure and the exhaust gas is ejected along with the flame In particular, since the oxygen value supplied at the beginning of the converter automation operation is excluded, there arises a problem that the automatic operation is difficult due to a variation caused by the operator.

Korean Patent Laid-Open Publication No. 2014-0106847 Korean Patent Laid-Open Publication No. 2012-0072491 Korean Patent Laid-Open Publication No. 2010-0117228

DISCLOSURE Technical Problem Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and it is an object of the present invention to accurately calculate the amount of decarburization oxygen involved in the decarburization reaction after ignition at the time of recirculation, It is possible to perform normal converter operation and normal molten steel production by supplying the required amount of oxygen by subtracting the amount of decarbonated oxygen involved in the decarburization reaction from the calculated total amount of the deodorizing reaction, The present invention has been made to solve the above problems.

According to an aspect of the present invention, there is provided a method of charging a cable, the method comprising: charging a charcoal and scrap in a converter; A step in which the lance is placed in the converter while maintaining the charged electric power and driving the fan to maintain the pressure of the airflow passing through the hood at a negative pressure; An ignition step of partially opening the oxygen valve connected to the lance to supply oxygen into the converter while metering the oxygen supply amount to ignite; Measuring a pressure change point of the flue gas in a hood located at an upper portion of the converter and measuring a temperature change point of the flue gas after a point at which the pressure change point of the flue gas is measured; And a refining step of obtaining the required oxygen amount calculated according to the following equations (1) and (2) and controlling the oxygen valve so as to be supplied in an amount, preferably an equal amount, A method of tuning a converter comprising:

[Equation 1]

Required amount of oxygen = (total demanded amount - amount of decontamination)

&Quot; (2) "

Decant oxygen amount = (total amount of water - (amount per minute / 60 * (pressure change point - temperature change point))

An out-of-phase step of shutting off the oxygen valve and exiting the lance out of the converter in the ignition detection step when it is detected that ignition is not performed; A tidal phase to tilt the converter; A weighing stage in which the sedative is weighed; Step in which the lance is inserted into the converter; And a re-ignition step of charging the sediment and weighing the charcoal prior to or after partially opening the oxygen valve connected to the lance or simultaneously with partial opening.

The partial opening of the oxygen valve in the ignition step may be performed by opening the oxygen valve to supply oxygen in an amount of 40 to 80% of the theoretical blowing amount required for blowing.

The basis weight of the sedative in the weighing step may be performed by weighing the amount by which the sedative can be spontaneously ignited by the temperature in the furnace.

The charging step may further include a low-smoldering step of lowering the inert gas at the lower portion of the converter during the charging of the charcoal and the scrap.

The low-flow rate of the inert gas in the dew condensation step may be sufficient to expose the molten iron to the scrap as the electric wire and the scrap are stirred.

According to the method for tuning the converter according to the present invention, it is possible to accurately calculate the amount of decarburization oxygen involved in the decarburization reaction after ignition at the time of switching to the converter, and based on the calculated total amount of decarburization, It is possible to operate a normal converter in which the required oxygen amount, which is obtained by subtracting the amount of decarburization oxygen involved in the decarburization reaction, is supplied in an amount, preferably an equilibrium amount, divided by unit time, thereby enabling a high-quality molten steel Can be stably produced.

Fig. 1 is a configuration diagram schematically showing a configuration of a converter.
2 is a flow chart of a method for winding a converter according to the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

A general configuration of a converter to which the method of winding a converter according to the present invention can be applied is schematically shown in Fig.

As shown in Fig. 1, a brewing apparatus for producing molten steel controlled by a method of blowing a converter according to the present invention includes a converter 1 for receiving and refining molten iron and scrap; A lance (2) which is pierced into the converter (1) to supply oxygen; An oxygen valve (3) for controlling the flow of oxygen supplied to the lance (2); A hood (4) for exhausting the exhaust gas generated from the converter (1); A primary dust collector 5 connected to the hood 4; A fan 6 for forming a negative pressure in the hood 4 to exhaust the exhaust gas; A pressure sensor P1 for measuring the pressure change point of the flue gas in the hood 4 and a temperature sensor T1 for measuring the temperature change point of the flue gas after the pressure sensor P1 . The controller 11 receives signals from the pressure sensor P1 and the temperature sensor T1 and controls the converter 1, the lance 2, the oxygen valve 3 and the fans 6, And an input device 12 for inputting parameters and control signals for controlling the controller 11.

By using a device for blowing with the above-described configuration, a method of blowing a converter according to the present invention is performed, and normal blowing can be performed. However, since the present invention is applied to a device for blowing It is to be understood that the invention is not intended to be limited to these embodiments.

As shown in Fig. 2, the method for winding a converter according to the present invention includes charging (S1) charging charcoal and scrap into the converter 1; The step S2 of setting the charged lantern 1 and driving the fan 6 to keep the pressure of the airflow passing through the hood 4 at a negative pressure and putting the lance 2 into the converter 1, ; An ignition step (S3) of partially opening the oxygen valve (3) connected to the lance (2) to supply oxygen into the converter (1) while metering the oxygen supply amount to ignite; The ignition timing is determined by measuring the pressure change point of the exhaust gas in the hood 4 located at the upper portion of the converter 1 and measuring the temperature change point of the exhaust gas after the point at which the pressure change point of the exhaust gas is measured (S4); And the required oxygen amount calculated according to the following equations (1) and (2), and controls the oxygen valve (3) to be supplied in an amount, preferably an equal amount, divided by the required oxygen amount per unit time, (S5): < RTI ID = 0.0 >

[Equation 1]

Required amount of oxygen = (total demanded amount - amount of decontamination)

&Quot; (2) "

Decant oxygen amount = {total transmission amount - [transmission per minute / 60 * (pressure change point - temperature change point)]}

The charging step S1 is carried out by charging charcoal and scrap in the converter, and charging charcoal and scrap for the production of molten steel by inclining the charger. At this time, the charcoal can be charged into the converter through the ladle (not shown for the sake of simplification of the drawing), which is usually produced in the blast furnace, and the scrap can be charged into the converter through the subsidiary material transport facility and the hopper. Scrap means a scraper that is produced when manufacturing scaffolds such as plates, rods, tubes, etc., and scrap is literally a metal scraper. In view of the production of molten steel, there is a limit to the amount used because it falls economically, but the utilization of scrap has recently become higher due to depletion of raw materials such as iron ore. On the other hand, when scrap is charged into a converter with charcoal, it may happen that it floats on the charcoal due to the specific gravity difference, etc., and floating of the scrap is caused by the carbon in the charcoal and blown into the converter It may affect the oxidation reaction between oxygen, which may lead to non-convergence of the converter. As described above, as described above, the normal molten steel can not be produced, and the oxygen remains in the furnace, and after a certain period of time, the oxygen in the furnace and the carbon in the molten iron react instantaneously. It may cause a problem that an abnormal operation state frequently occurs such as a momentarily high temperature is generated due to the presence of residual oxygen or the like. The possibility of this non-firing is increased as the amount of scrap added to the charcoal is increased, and when the amount of charcoal based on the total amount of filler is less than 85%, that is, when the amount of scrap is more than 15%. Therefore, the method of tuning the converter according to the present invention can contribute to lowering the possibility of non-ignition by the high scrap charge amount and raising the possibility of ignition, thereby enhancing the productivity of molten steel by normal blowing using the converter.

In the step S2, the furnace is charged and oxygen is supplied into the furnace by driving the fan to make the lance into the furnace while maintaining the pressure of the airflow passing through the hood at a negative pressure. .

The ignition step S3 is performed by partially opening the oxygen valve connected to the lance and metering the oxygen supply amount to supply oxygen into the converter to ignite the molten iron. The metering of the oxygen supply quantifies the total amount of gas supplied until the ignition is complete and a normal culling process is performed, and such metering can be performed by installation of the flow meter. The furnace is charged with a high-temperature charcoal and maintains a high temperature. The charcoal also contains a large amount of carbon, so that the carbon can be oxidized by oxygen and be ignited.

In the ignition detection step S4, the pressure change point of the exhaust gas is measured in the hood located at the upper portion of the converter, and the temperature change point of the exhaust gas is measured after the point at which the pressure change point of the exhaust gas is measured. . That is, in the present invention, to determine the ignition timing, the pressure change and the temperature change of the exhaust gas by the reaction of oxygen and carbon are separately measured to determine whether or not the ignition is correctly ignited and the ignition timing. In other words, it can be determined that the oxygen supplied to the converter reacts with the carbon in the charcoal and the oxidation reaction of the carbon becomes continuous. Then, the combustion heat due to the oxidation reaction of carbon is followed by the continuous reaction of oxygen and carbon Can be continued and the curing process can be stably carried out to decarburize the carbon in the molten iron to make the molten iron into the molten iron.

Particularly, in the present invention, the pressure change and the temperature change are measured at different positions. Preferably, the pressure change may be measured at the hood immediately above the converter, more preferably at the tip of the hood, directly above the converter below the hood, which is the pressure of the explosively increasing flue gas at ignition Because it can detect the most accurately and quickly. Preferably, the temperature change can also be measured at the primary dust collector, more preferably at the inlet of the primary dust collector, ie, the inlet of the flue gas into the primary dust collector, It is preferable to provide a temperature sensor at the inlet of the primary dust collector, especially the primary dust collector, in order to operate the primary dust collector at low temperature. It is more accurate to regard the pressure change point and the temperature change point as the ignition in the case where it is confirmed that the measurement position is different according to the characteristic of the measurement object and both of the pressure change and the temperature change are measured, It is possible to confirm the ignition and stably operate the blowing process. The pressure of the flue gas changes abruptly from ignition due to the explosive oxidation reaction between oxygen and carbon in the charcoal and the pressure is proportionally lowered with increasing time and distance from the point of pressure generation due to the nature of the flue gas, , It is advantageous and accurate to measure the pressure change at the position closest to the converter as much as possible, since it is likely to vary depending on, for example, the pressure applied to the hood due to the rotational speed of the fan, , It is advantageous to measure at a position far from the converter since the temperature is also lowered proportionally but since the hot wire which is already in a high temperature state is charged in the converter without being abruptly lowered by the pressure, The determination of whether to ignite or not, By changing the two different detection may be more accurate to determine whether the ignition. Usually, the flue gas is almost instantly changed in pressure after ignition. Thereafter, the flue gas reaches the primary dust collector after a few seconds to several tens of seconds although there is a difference depending on the equipment.

However, the amount of oxygen not reacted with the carbon in the charcoal supplied before the ignition and the amount of oxygen reacted with the carbon in the charcoal after the ignition was measured due to the difference in the distance and time between the pressure change point and the temperature change point It is necessary to correct the amount of oxygen contributing to the decarburization reaction. That is, most of the oxygen supplied into the converter before ignition can be exhausted through the hood without contributing to the oxidation reaction of carbon, that is, the decarburization reaction. At this time, the oxygen discharged without contributing to the decarburization reaction contributes to the refining of the charcoal And thus does not contribute to the total amount of the blast. However, since the ignition implies that the carbon in the molten iron reacts with the oxygen supplied into the converter once the complex has been achieved, the oxygen supplied after the ignition contributes to the total amount of shunting, The oxygen supplied after ignition may not be preferable.

In addition, in order to assist the determination of the ignition caused by the measurement of the pressure change and the temperature change, the pressure detected by the pressure sensor located at the tip of the hood and the pressure detected through the input device are compared, Or if the temperature detected by the temperature sensor installed at the inlet of the primary dust collector is not more than 500 ° C, preferably not less than 600 ° C for 20 seconds, preferably not more than 25 seconds, Can be detected.

The refining step (S5) calculates the required oxygen amount calculated according to the following equations (1) and (2), controls the oxygen valve to be supplied in an amount, preferably an equal amount, divided by the required oxygen amount per unit time It consists of sending and refining;

[Equation 1]

Required amount of oxygen = (total demanded amount - amount of decontamination)

&Quot; (2) "

The required amount of oxygen is an amount of oxygen further required to refine molten iron in the refining step (S5) after the ignition detecting step (S4), and as shown in the above-mentioned formula (1) Can be calculated.

Here, the total amount of shunting demand is based on the content and dose of other elements including carbon in the charcoal used, the composition and amount of scrap used, and the composition and consumption of other raw materials such as quicklime, fluorite, light dolomite and ferrosilicon , Which can be calculated theoretically, preferably stoichiometrically.

The decarbonized oxygen amount can be defined as the amount of oxygen involved in carbon in the molten iron after ignition, which is reacted with oxygen to oxidize and remove into the exhaust gas. In practice, the decarbonized oxygen amount can be calculated as shown in Equation 2, and both the pressure change point and the temperature change point are measured in terms of time, and the pressure change point and the temperature change point are determined as described above .

According to the method of tuning the converter according to the present invention having the above-described configuration, it is possible to precisely calculate the amount of decarbonized oxygen involved in the decarburization reaction after ignition at the time of switching to the ignition, It is possible to operate a normal converter in which the required amount of oxygen, which is subtracted from the amount of decarburization oxygen involved in the decarburization reaction, is supplied in an amount, preferably an even amount, divided per unit time in the calculated total amount of the deodorizing reaction, It is possible to stably produce high-quality molten steel having a carbon content.

In the ignition detection step S4, when it is detected that ignition is not performed, a re-ignition step may be performed, and the ignition step may block the oxygen valve 3 and cause the lance 2 to turn on the converter 1 ) Out-of-phase step S11; A tilting step S12 for tilting the converter 1; A weighing step (S13) in which the sedative is weighed; Step S14 in which the lance 2 is inserted into the converter 1; And a re-ignition step (SlO) of charging the sediment and igniting the charcoal before or after partially opening the oxygen valve (3) connected to the lance (2) or simultaneously with partial opening.

The outlier step S11 is performed by closing the oxygen valve and deflecting the lance out of the converter when ignition is not performed, which is understood as a preliminary operation to perform the tilting step S12 for tilting the converter . It is necessary to exclude the lance from the outside of the furnace so as to tilt the furnace so as to supply kinetic energy to the furnace and the scrap in the furnace so as to expose the furnace on the scrap. After the extra step S11, the tilting step S12 is performed. In the tilting step S12, the converter can be tilted 2 to 3 times.

Thereafter, a weighing step (S13) may be performed to weigh the sedative, and the sediment to be added into the converter may be weighed in this weighing step (S13); Placing the lance into the converter in a subsequent in-situ step S14; And ignition may be induced by injecting a calmed sedative before or after partial opening of the oxygen valve connected to the lance or simultaneously with partial opening.

The sedative agent is composed of a carbonaceous fuel, preferably a paper-made fuel such as pulp pulp, and can form a flame by the furnace internal temperature, which is usually maintained at 300 to 400 DEG C, But it is possible to form a flame with the aid of non-excessive oxygen supplied to the furnace by the partial opening of the furnace, Thereby helping to partially melt and / or cut and / or perturb scraps floating on the charcoal, thereby causing the charcoal under the scrap to be exposed, thereby allowing the carbon contained in the charcoal to react with oxygen, So that ignition can be performed.

The partial opening of the oxygen valve in the ignition step (S3) may preferably be performed by opening the oxygen valve to supply oxygen in an amount of 40 to 80% of the amount of the required amount of the blowing. If the amount of oxygen supplied by the partial opening of the oxygen valve is less than 40% of the optimum amount, there may be a problem that ignition does not occur due to lack of oxygen. On the contrary, if it exceeds 80% In the case where delayed complexation occurs in which oxygen in the molten metal reacts instantaneously with oxygen after a certain period of time has elapsed while maintaining the state of oxygen remaining in the furnace at the time of non-firing, because of the presence of residual oxygen, Which may cause a problem in that an abnormal operation state frequently occurs.

The basis weight of the sedative in the basis weighting step (S13) can be preferably performed by weighing the amount by which the sedative can be spontaneously ignited by the temperature in the furnace. The amount of the sedative that is weighed on the basis of the basis weight may be varied depending on the scale of the converter to which the sedative is injected. For example, when the sediment composed of pulp is used as a converter having an internal volume of about 200 m3, By weight. If the amount of the basis weight is less than 10 kg, there may be a problem that the amount of the sedative functioning as a complexing agent is insufficient and the complexation is not normally performed. On the other hand, when the basis weight is more than 200 kg, So that there is a problem that it becomes economically undesirable.

The charging step S1 may further include a low-smoothing step of lowering the inert gas at the lower portion of the converter during the charging of the charcoal and the scrap. In the smoothing step, the low-smoke is performed by blowing an inert gas, such as nitrogen, And the amount of the inert gas flowing through the inert gas may be sufficient to expose the molten metal to the scrap by being stirred with the scrap metal and the scrap metal. The amount of the scrap metal may vary depending on the scale of the converter, for example, And can be an amount within a range of 5 to 10 Nm 3 based on a converter having an internal volume of about 200 m 3. When the flow rate is less than 5 Nm3, the effect of agitation of the electric arc furnace wire and the scrap is insufficient, which may result in insufficient atmosphere formation for reliable ignition. On the contrary, when the flow rate exceeds 10 Nm3, There may be a problem that the internal environment of the converter becomes unstable due to excessive deodorization and excessive stirring.

1: converter 2: lance
3: oxygen valve 4: hood
5: primary dust collector 6: fan
11: Controller 12: Input device
P1: Pressure sensor T1: Temperature sensor
S1: charging step S2: in-phase step
S3: Ignition step S4: Ignition detection step
S5: refining step S10: re-ignition step
S11: extrinsic step S12: tilt step
S13: Basis step S14: In-situ step

Claims

A charging step of charging charcoal and scrap in the converter;
A step in which the lance is placed in the converter while maintaining the charged electric power and driving the fan to maintain the pressure of the airflow passing through the hood at a negative pressure;
An ignition step of partially opening the oxygen valve connected to the lance to supply oxygen into the converter while metering the oxygen supply amount to ignite;
The pressure change point of the flue gas is measured at the tip of the hood immediately above the converter and the temperature change point of the flue gas is measured at the tip of the primary dust collector connected to the hood after the point at which the pressure change point of the flue gas is measured An ignition detection step of determining the ignition timing by the ignition detection step; And
A refining step of calculating a required oxygen amount according to the following equations (1) and (2), controlling the oxygen valve to supply the required oxygen amount divided by the unit time,
And the air flow direction of the air flow passage.
[Equation 1]
Required amount of oxygen = (total demanded amount - amount of decontamination)
&Quot; (2) "
Decant oxygen amount = {total transmission amount - [transmission per minute / 60 * (pressure change point - temperature change point)]}

delete

The method according to claim 1,
In the ignition detection step, when it is detected that ignition is not performed,
An out-of-phase step of shutting off the oxygen valve and expelling the lance out of the converter;
A tidal phase to tilt the converter;
A weighing stage in which the sedative is weighed;
Step in which the lance is inserted into the converter; And
A re-ignition step of charging a calm sediment prior to or after partially opening the oxygen valve connected to the lance or simultaneously with partial opening and igniting the charcoal;
Wherein the first and second taps are formed on the outer surface of the housing.

The method according to claim 1 or 3,
Wherein the partial opening of the oxygen valve is performed by opening the oxygen valve to supply oxygen in an amount of 40 to 80% of the theoretical amount required for the blowing.

The method of claim 3,
Wherein the basis weight of the sedative in the weighing step is performed by weighing the amount by which the sedative can be spontaneously ignited by the temperature in the furnace.

The method according to claim 1,
Wherein the charging step further comprises a low-smoothing step of lowering the inert gas in the lower portion of the converter during the charging of the charcoal and the scrap.

The method according to claim 6,
Wherein the low-flow rate of the inert gas in the low-emission stage is sufficient to expose the molten iron to the scrap by being stirred with the molten iron and the scrap.