WO2019230657A1

WO2019230657A1 - Converter blowing method

Info

Publication number: WO2019230657A1
Application number: PCT/JP2019/020925
Authority: WO
Inventors: 峻秀貞本; 福山　博之; 洋仁井谷
Original assignee: 日本製鉄株式会社
Priority date: 2018-05-28
Filing date: 2019-05-27
Publication date: 2019-12-05
Also published as: CN111742066B; TW202003864A; KR102343595B1; JP6962465B2; TWI700373B; JPWO2019230657A1; CN111742066A; KR20200109373A

Abstract

A converter blowing method for blowing oxygen gas onto a molten pig iron surface in a converter from a nozzle of a top-blown lance. The converter blowing method comprises: a rate calculation step of calculating a dust generation rate in the converter by determining the amount of dust in exhaust gas generated during blowing; an error amount calculation step of calculating an error amount in the dust generation rate calculated in the rate calculation step, with respect to a predetermined relationship R1 between the number of use of the top-blown lance and the dust generation rate when a lance gap, which is the distance between the molten pig iron surface and the tip of the top-blown lance, is made an optimum interval; and a position adjusting step of adjusting the lance gap during the blowing in order to correct the error amount determined in the error amount calculation step from a predetermined relationship R2 between a change amount of the lance gap and a change amount of the dust generation rate.

Description

Converter blowing method

This disclosure relates to a converter blowing method using an upper blowing lance.

In the converter, blowing is performed using an upper blowing lance (hereinafter referred to as “lance” as appropriate). In this blowing, oxygen gas is jetted from the nozzle hole provided in the lance toward the hot metal surface (molten metal surface), and the hot metal is stirred and Si, Mn, P, and C are removed by an oxidation reaction. During blowing, dust is generated from the converter due to the rebound and decarburization reaction of the oxygen gas sprayed from the nozzle hole of the lance. The generated dust is discharged together with the exhaust gas. This dust is mainly composed of iron (iron, iron oxide), and if discharged, it will lead to iron loss, so it is desirable to reduce it.

When blowing with an upper blowing lance, the shape of the hot metal surface in the converter changes when oxygen gas collides with the hot metal surface due to the acid feed rate and the lance height (nozzle tip position).
At a constant acid feed rate, the smaller the lance gap, which is the distance between the hot metal surface and the nozzle tip, the hot metal shape when the oxygen gas collides with the hot metal surface becomes a waterfall (reverse Ω-shaped cross section). It is known that the amount of dust generated can be reduced because the generated dust does not scatter and is easily taken into the hot metal. This is called hard blow.
On the other hand, it is known that if the lance gap is made too small, the nozzle is strongly affected by the heat from the hot metal surface, and therefore the wear of the nozzle becomes severe and the life of the lance is shortened. Thus, since the life of the lance is shortened, the frequency of lance replacement is increased, which adversely affects the operation.

From the above, the lance gap has an optimum interval for reducing the amount of dust generated while maintaining the life of the lance, and it is desired to perform blowing by the interval. The optimum interval of the lance gap (hereinafter referred to as “optimum lance gap” as appropriate) is set according to the size of the converter and the acid feed rate.
In order to set the lance gap to an optimum interval, it is necessary to grasp the height of the hot metal surface, and for example, there is a technique disclosed in Japanese Patent Application Laid-Open No. 11-52049. Specifically, a moving microwave transmission / reception antenna installed in the sublance hole of the upper hood of the converter after charging hot metal and scrap or can alloy (alloy iron in a drum can) in the converter In this method, microwaves are transmitted toward the furnace, and the height of the hot metal surface (water surface level) is measured from the received signal.

The measurement of the height of the hot metal surface is performed after the hot metal is charged into the converter and before the start of blowing (before the start of blowing). In Japanese Patent Laid-Open No. 11-52049, there is no clear description of the time required for the measurement of the hot metal surface height. Therefore, it is difficult to measure the hot metal surface height every time the molten iron or the like is charged into the converter.

Therefore, based on the measurement value of the hot metal surface height when actually measured with a microwave hot metal surface meter, the estimated value of the hot metal surface height (estimated hot metal surface height) for each blowing operation when not actually measured is expressed by the following formula ( 1).
(Estimated hot metal surface height) = {(WTn−WT ₀ ) / (ρπr ₀ ² )} + l ₀ (1)
Here, ρ is the iron specific gravity, r ₀ is the cross-sectional radius (inner diameter) of the converter near the hot metal surface, ₁₀ is the measured value of the hot metal surface height with a microwave hot metal surface meter, and WT ₀ is with the microwave hot metal surface meter. The amount of iron charged to the converter at the time of measurement, WTn is the amount of iron charged to the converter at the time of calculating the estimated hot metal surface height.

However, since the refractory stuck to the inner surface of the converter is repeatedly worn and repaired, the cross-sectional radius of the converter changes with each blowing. For this reason, every time when blowing is repeated from the measurement of the hot metal surface height by the microwave hot metal surface meter, a difference occurs between the estimated hot metal surface height and the actual hot metal surface height. For this reason, the lance gap cannot be set to an optimum interval.

This disclosure has been made in view of such circumstances, and an object thereof is to provide a converter blowing method capable of performing blowing with an appropriate lance gap even when the hot metal surface height is not actually measured.

As a result of earnestly examining a method for setting an optimal lance gap in a method of charging an upper blowing lance into a converter and performing blowing, the present inventors have found the following knowledge.
The lance gap can be estimated from the dust generation speed by utilizing the fact that the dust generation speed changes due to the fluctuation of the lance gap.
However, as the number of times the top blow lance is used increases, the flow of oxygen gas (oxygen jet) changes due to the deformation of the lance (nozzle shape), so the dust generation speed changes even if the lance gap is constant. . That is, it is difficult to estimate the lance gap only with the dust generation rate.
Therefore, the lance gap is adjusted based on the dust generation speed that also takes into account the influence of the number of times the lance is used.
This indication was made based on the above knowledge, and the summary is as follows.

A converter blowing method according to an aspect of the present disclosure is a converter blowing method in which oxygen gas is blown from a nozzle of an upper blowing lance to a hot metal surface in a converter, and the amount of dust in exhaust gas generated during blowing And calculating the dust generation speed in the converter, and the upper limit when the lance gap, which is the distance between the hot metal surface and the tip of the upper blowing lance, is determined in advance, is an optimal interval. A deviation amount calculating step for obtaining a deviation amount of the dust generation speed calculated in the speed calculation step with respect to a relationship R1 between the number of times the blow lance is used and the dust generation speed, a change amount of the lance gap obtained in advance, A position adjustment step of adjusting the lance gap during the blowing to correct the deviation amount obtained in the deviation amount calculation step from the relationship R2 with the amount of change in dust generation speed.

According to the present disclosure, it is possible to provide a converter blowing method capable of performing blowing with an appropriate lance gap even when the hot metal surface height is not actually measured.

It is explanatory drawing of the refining equipment to which the converter blowing method which concerns on one Embodiment of this indication is applied. It is explanatory drawing of the dust concentration measuring apparatus of the refining equipment shown by FIG. 1A. It is sectional drawing of the front end side of the upper blowing lance used with the refining equipment shown by FIG. 1A. FIG. 2B is a cross-sectional view of the tip side of the top blowing lance showing a state in which the nozzle is worn by use in the top blowing lance shown in FIG. 2A. It is a graph which shows the relationship between the variation | change_quantity of the lance gap in each use frequency of an upper blowing lance, and the variation | change_quantity of the dust generation speed in a converter. It is a graph which shows the relationship between the frequency | count of use of an upper blowing lance, and the dust generation speed in a converter when making a lance gap into the optimal space | interval.

Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings.

The converter blowing method according to an embodiment of the present disclosure is a blowing method used in the refining equipment 9 shown in FIGS. 1A and 1B. First, after describing the refining equipment 9 of the present embodiment, the converter blowing method of the present embodiment will be described.

1A and 1B, the refining equipment 9 includes a converter 10, an upper blow lance 11 (hereinafter referred to as “lance” as appropriate), and an exhaust gas treatment device 17.

As shown in FIG. 2A, the lance 11 is a member for spraying oxygen gas onto the molten iron surface S in the converter 10 from a nozzle 11A described later. The lance 11 has a cylindrical shape and can be moved upward and downward in the vertical direction by a lifting device (not shown). By moving the lance 11 up and down, the lower part (front end side) of the lance 11 can be inserted into or removed from the converter 10. The lance 11 can be stopped at an arbitrary height position by the lifting device. The lance gap G described later can be adjusted by the vertical movement of the lance 11. Note that the arrow UP in FIG. 2A indicates the upper side in the vertical direction. An arrow AXL in FIG. 2A indicates the central axis of the lance 11.

Further, the tip of the lance 11 is a nozzle portion, and a plurality of nozzles 11A are provided in the nozzle portion. These nozzles 11 </ b> A are through holes having a narrowed middle portion, that is, Laval nozzles (De Laval nozzle), and a plurality of nozzles 11 </ b> A are provided on a concentric circle centered on the central axis AXL of the lance 11 at regular intervals. Yes. The nozzle 11A may also be formed on the central axis AXL of the lance 11.

As shown in FIG. 2A, oxygen gas A supplied to the lance 11 is jetted from the nozzle 11A. Here, the jet of the oxygen gas A injected from the nozzle 11 </ b> A toward the hot metal surface S, after forming the jet core, spreads at an angle with a free spread angle φ, and collides with the hot metal in the converter 10. Thus, a hot spot recessed in a waterfall shape is formed on the hot metal surface S (note that the hot spot is not shown in FIG. 2A).

As shown in FIG. 1A, the exhaust gas treatment device 17 is a device that treats exhaust gas containing dust generated from the converter 10 (gas mainly composed of CO, CO ₂ , and N ₂ gas) in a wet process. The exhaust gas treatment device 17 includes a furnace port hood 18, an exhaust gas duct 12, a primary dust collector 13, a secondary dust collector 19 and the like.

The furnace port hood 18 and the exhaust gas duct 12 are provided above the converter 10. In addition, a primary dust collector 13, a secondary dust collector 19, and an induction blower (not shown) are sequentially provided on the downstream side of the exhaust gas duct 12. The exhaust gas from the converter 10 is sucked by an induction blower, passes through the furnace port hood 18 and the exhaust gas duct 12, and is removed by the primary dust collector 13 and the secondary dust collector 19. Further, the dust-exhausted exhaust gas passes through an induction blower, and the exhaust gas with a high CO concentration is sent as a valuable gas to a gas holder (not shown), while the exhaust gas with a low CO concentration is burned at the top through a chimney (not shown) and is discharged into the atmosphere. To be dissipated.

The primary dust collector 13 and the secondary dust collector 19 each collect exhaust gas by wet type, and for example, venturi scrubber is used.

Dust collection water (indicated by arrow W in FIGS. 1A and 1B) introduced into the primary dust collector 13 takes in dust in the exhaust gas and becomes dust collection water containing dust. Dust collection water is temporarily stored in a lower water tank 14 provided immediately below the primary dust collector 13, and then sent to a dust collection water treatment device (not shown) to remove dust in the dust collection water.

Further, as shown in FIG. 1B, the exhaust gas treatment device 17 includes a dust concentration measurement device (hereinafter referred to as “measurement device” as appropriate) 20 for measuring the dust concentration. The measuring device 20 includes a pump 15 that continuously collects the collected water that has passed through the primary dust collector 13, and a vibratory density meter 16 that measures the density of the collected water. In this measuring device 20, the collected water is continuously collected by the pump 15, and the vibration density meter 16 is used to continuously measure the dust concentration in the collected water per unit time according to the relationship with the water temperature at that time. (The amount of dust in the exhaust gas generated during blowing of the converter 10 is continuously measured). Here, at least 90% or more of the dust generated in the converter 10 is removed by the primary dust collector 13. For this reason, the dust concentration in the exhaust gas of the converter 10 can be estimated by measuring the dust concentration in the collected water collected by the primary dust collector 13.
Note that the collected water after the dust concentration measurement is returned to the lower water tank 14.

Next, the converter blowing method of this embodiment is demonstrated.
In the converter blowing method of the present embodiment, as shown in FIGS. 1A and 1B, the tip side of the lance 11 is inserted into the converter 10, and the hot metal surface S in the converter 10 is inserted from the nozzle 11 </ b> A of the lance 11. This is a blowing method in which oxygen gas A is blown onto the steel and decarburized. And this converter blowing method is characterized by making the lance gap G (see FIG. 2A), which is the distance between the hot metal surface S and the tip of the lance 11, an optimum interval when blowing. Note that the blowing may be not only top blowing but also top bottom blowing combined with bottom blowing.

Specifically, the converter blowing method described above includes a speed calculating step of calculating a dust generation speed GR by obtaining a dust amount in exhaust gas generated during blowing,
Deviation amount calculation for obtaining the deviation amount of the dust generation speed GR calculated in the speed calculation process with respect to the relationship R1 between the number of times the lance 11 is used and the dust generation speed GR when the lance gap G is set to an optimum interval. Process,
In order to correct the deviation amount obtained in the deviation amount calculating step from the relationship R2 between the variation amount of the lance gap G and the variation amount of the dust generation speed GR obtained in advance, the lance gap G is adjusted during the blowing. Position adjustment process;
It is the method which has.

The speed calculation step, the deviation amount calculation step, and the position adjustment step described above are processed by a computer (calculation means) of an operator who performs the converter operation. Further, the relationship R1 used in the deviation amount calculation step and the relationship R2 used in the position adjustment step are made into a database, for example. The above-mentioned computer receives various information for performing the converter operation, and also controls the converter operation (for example, start and stop of blowing, adjustment of the lance gap G) and the like (that is, the computer controls It becomes a means).
The computer described above is a conventionally known computer including a RAM, a CPU, a ROM, an I / O, and a bus for connecting these elements, but is not limited thereto.

First, each calculation method of the above-described dust generation speed, relation R1, and relation R2 will be described.

In the converter operation, as shown in FIG. 1A, a lance 11 is inserted into the furnace from above the converter 10, and oxygen gas A is blown onto the molten iron at a high speed, thereby causing impurities such as Si, C, P, and Mn. Is removed (decarburized). At that time, fine dust is generated by the rebound of the sprayed oxygen gas A on the hot metal surface S and the bubble breaking of the CO gas on the hot metal surface S accompanying the decarburization reaction.
The generated dust is sucked into the exhaust gas duct 12 through the furnace port hood 18 together with the exhaust gas generated from the converter 10 and is contained in the dust collection water supplied from the primary dust collector 13 while being collected through the lower water tank 14. It is sent to the processor and separated and recovered. Note that the dust generated from the converter 10 is separated from the exhaust gas by the dust water sprayed by the primary dust collector 13, and the exhaust gas is sent downstream.

(Calculation method of dust generation rate in converter 10)
As shown in FIG. 1B, in the measuring device 20, the collected water is continuously collected by the pump 15, and the vibration density meter 16 is used to collect the collected water per unit time according to the relationship with the water temperature at that time. Perform continuous measurement of dust concentration. The dust generation rate during blowing of the converter 10 can be calculated from the product of the dust concentration measured by the above method and the amount of water sprayed per unit time (the amount of water sprayed from the primary dust collector 13).

(Calculation method of relation R2)
A hot metal surface S in the converter 10 (for example, about 400 tons of molten iron in the converter) is measured by a microwave hot metal surface meter (not shown), and is removed from the lance gap G for each use of the lance 11 and the acid supply. The relationship shown in FIG. 3 is obtained by estimating the relationship with the average dust generation rate GR in the decarburization peak period when charcoal occurs preferentially. The number of uses N of the lance 11 corresponds to the number of times the converter 10 is blown (the same applies hereinafter). In FIG. 3, when the lance is used about 50 times (when the number of times of use is low: black circle in FIG. 3) and when it is about 200 times (when the number of uses is high: white circles in FIG. 3) ), The same behavior is shown even within the range of 50 to 200 times.
As shown in FIG. 3, the dust generation rate GR increases linearly as the lance gap G (here, in the range of 2500 to 3000 mm) increases. Regardless of the deformation of the nozzle 11A of the lance 11, the inclination is constant. Here, the “tilt” is a gradient obtained by dividing the change amount of the dust generation speed GR by the change amount of the lance gap G (that is, the relationship R2).

(Calculation method of relation R1)
FIG. 4 shows the dust generation rate GR at the peak of decarburization with respect to the lance usage number N when the hot metal surface S in the converter 10 is measured with a microwave hot metal surface meter and the lance gap G is set to an optimum interval. It becomes a relationship (that is, relationship R1).
As shown in FIG. 4, when the lance gap G is set to an optimum value, the dust generation speed GR increases as the lance usage number N increases. The curve shown in FIG. 4 is y = 6.9492x ^0.0698 , where y is the dust generation speed and x is the number of times the lance is used.

The dust generation speed GR of the converter 10 is calculated by the above-described method, and the speed calculation process, the deviation amount calculation process, and the position adjustment process are sequentially performed using the relations R1 and R2 obtained in advance.

(Speed calculation process)
First, based on the estimated hot metal surface height obtained by the above equation (1), the lance height is set so that the optimum lance gap G is obtained, and the converter 10 is blown, Using the smelting method, the average dust generation amount (dust amount) in the exhaust gas generated during the decarburization peak period is obtained, and the dust generation rate GR of the converter 10 is calculated.

(Deviation amount calculation process)
The dust generation of the converter 10 calculated in the speed calculation step based on the relationship R1 between the number of times of use of the top blow lance 11 in the optimum lance gap and the dust generation speed of the converter 10 shown in FIG. Find out how much the speed GR deviates. Specifically, the difference (that is, the amount of deviation) between the value of the dust generation speed GR obtained from FIG. 4 and the value of the dust generation speed calculated in the speed calculation step is determined according to the lance usage number N.
Here, when the calculated value of the dust generation speed GR is lower than the value of the dust generation speed GR corresponding to the lance usage number N shown in FIG. Since it shows that it is small (hard blow), the lance gap G needs to be adjusted largely. On the other hand, when the calculated dust generation rate GR is higher than the value of the dust generation rate GR corresponding to the lance usage number N shown in FIG. 4, the actual lance gap G is larger than the optimum lance gap G. (It is a soft blow), it is necessary to adjust the lance gap G small.

(Position adjustment process)
In order to correct the deviation amount obtained in the deviation amount calculation step from the relationship R2 between the variation amount of the lance gap G and the variation amount of the dust generation speed GR, which is obtained in advance as shown in FIG. Adjust the lance gap G. In the present embodiment, the dust generation speed GR is obtained and the lance gap G is adjusted during the maximum decarburization period by blowing.

As described above, the gradient obtained by dividing the change amount of the dust generation speed GR by the change amount of the lance gap G, which indicates the relationship R2 between the change amount of the lance gap G and the change amount of the dust generation speed GR, Regardless of whether or not From the relationship between the two, the adjustment amount of the lance gap G for correcting the deviation amount of the dust generation speed GR is obtained, and the lance gap G is adjusted during the blowing of the converter 10.

Specifically, the deviation amount of the dust generation speed GR obtained in the deviation amount calculation step is divided by the above-described gradient to obtain an adjustment amount of the lance gap G corresponding to the deviation amount of the dust generation speed GR. The lance gap G is adjusted by changing the height position of the lance 11 by the amount.
The above-described adjustment of the lance gap G (that is, the speed calculation step, the deviation amount calculation step, and the position adjustment step) may be performed once in one blowing, but may be performed multiple times as necessary. You can also

Here, as shown in FIG. 2B, the lance 11 has a tendency that when the number of uses N increases, the outlet portion of the nozzle 11A wears and the outlet diameter increases. When the outlet diameter of the nozzle 11A increases, energy loss occurs at the nozzle outlet, and the jet core length becomes shorter, so the momentum of the oxygen gas A decreases. However, in the converter blowing method of the present embodiment, the lance gap G is adjusted on the basis of the dust generation rate GR that also considers the influence of the number of times the lance 11 is used N. Even when the surface height is not actually measured, the converter 10 can be blown with an appropriate lance gap G. As a result, the amount of dust is excessive due to excessive soft blow (the lance gap G is increased), and the life of the lance 11 is significantly increased due to excessive hard blow (the lance gap G is decreased). It is possible to suppress and further prevent the decrease.

Next, examples performed for confirming the effects of the present disclosure will be described.
Here, the results of applying each method of the example and the comparative example when performing the blowing of the converter under the conditions of the hot metal amount of 400 tons and the optimum lance gap G of 3000 mm will be described.
In addition, an Example is a result of having performed the speed calculation process of the above-mentioned embodiment of this indication, the deviation | shift amount calculation process, and the position adjustment process one by one, and adjusting the lance gap G according to the dust generation speed GR. The example is a result of adjusting the lance gap based on the estimated hot metal height obtained from the above-described equation (1).

The evaluation is the average value of the number of charges until water leakage from the lance occurs in the number of trials for 10 times (N = 10) where the number of trials for one lance is 1 (N = 1). It was carried out using the lifetime and the measured dust generation amount (dust amount). The water leakage from the lance is caused by the water cooling structure of the lance, and is caused by wear resulting from long-term use of the lance. The amount of dust generated is calculated by adding the product of the dust concentration in the collected water measured by the dust concentration measuring device and the amount of water sprayed per unit time (1 second) through one charge. The value was divided by 400 tons.
The average life was about 300 charges in the example with respect to 250 charges in the comparative example, which was superior to 50 charges.
The amount of dust generated was reduced by 0.3 to 0.7 kg / ton in the average value of the test charge for one lance in the example, compared to the average value of 15 kg / ton in all the test charges in the comparative example.

From the above, it was confirmed that by applying the converter blowing method of the present disclosure, blowing can be performed with an appropriate lance gap, and the amount of dust generated can be reduced while maintaining the lance life.

As described above, the present disclosure has been described with reference to the embodiment. However, the present disclosure is not limited to the configuration described in the above-described embodiment, and the matters described in the claims are not limited. Other embodiments and modifications conceivable within the scope are also included. For example, a case where the converter blowing method of the present disclosure is configured by combining some or all of the above-described embodiments and modifications is also included in the scope of the right of the present disclosure.

In the said embodiment, although the case where the approximate expression calculated from the data which are the past operation results was used for relation R1 and relation R2, respectively was demonstrated, it is not limited to this, For example, it is the past operation. Data in a database that is a record may be used.

In the above embodiment, the gradient obtained by dividing the change amount of the dust generation speed of the converter by the change amount of the lance gap G is used to correct the deviation amount. This gradient is used based on the fact that it is constant regardless of the number of lances used N. For example, the amount of deviation can be corrected using the gradient obtained for each number of lances used.

Furthermore, in the said embodiment, the measuring apparatus 20 is equipped with the pump 15 and the vibration-type density meter 16, and collects dust collection water continuously with the pump 15, and uses the vibration-type density meter 16 and the time at that time. Although the dust amount is obtained by continuously measuring the dust concentration in the collected water per unit time according to the relationship with the water temperature, the present invention is not limited to this configuration. For example, the measuring device 20 is further equipped with a thermometer, and the collected water from which the exhaust gas has been wet collected is continuously collected, passed through the vibratory density meter 16 and the thermometer, and measured with the vibratory density meter 16. The dust amount may be obtained by calculating the dust concentration in the dust collection water from the difference between the density of the dust collection water and the density of pure water predicted from the temperature of the dust collection water measured with a thermometer. Specifically, the dust concentration is calculated using the following formula (2). In addition, the unit of the density | concentration or density in following formula (2) may be kg / m < ³ > of this embodiment, and may be g / L or kg / L.
C = (ρmeasure−ρwater) × ρdust / (ρdust−ρwater) (2)
However, C is estimated from the dust concentration (kg / m ³ ), ρmeasure: the density of collected dust water (kg / m ³ ) measured by the vibratory density meter 16, and ρwater: the temperature of the collected dust water measured by the thermometer. Density of pure water (kg / m ³ ), ρdust: density of dust particles (for example, 7800 kg / m ³ ).
Note that either the vibratory density meter 16 or the thermometer may be upstream or downstream.
For example, in the case of using a dust concentration measuring device using ultrasonic waves or light, the dust concentration is estimated from the attenuation rate. Therefore, although it is affected by the particle size of the dust, the measuring device 20 provided with the thermometer is used. The density of dust in the collected water, that is, the mass can be directly measured, and the dust particle size is not affected. Therefore, the dust concentration in the dust collecting water can be measured accurately and accurately. Thereby, the blowing of the converter 10 can be carried out with a more appropriate lance gap G.

Regarding the above embodiment, the following additional notes are disclosed.

(Appendix 1)
In the method of charging with the top blowing lance in the converter,
A speed calculating step of calculating a dust generation speed by measuring an amount of dust in exhaust gas generated during blowing of the converter;
The number of times of use of the upper blowing lance and the dust generation rate of the converter when the lance gap, which is the distance between the molten metal surface in the converter and the tip of the upper blowing lance, is set to an optimum interval, A deviation amount calculating step for obtaining a deviation amount of the dust generation speed of the converter calculated in the speed calculating step with respect to the relationship R1;
In order to correct the deviation amount obtained in the deviation amount calculation step from the relationship R2 between the change amount of the lance gap and the change amount of dust generation speed of the converter, which is obtained in advance, the blowing of the converter And a position adjusting step for adjusting the lance gap in the converter.

(Appendix 2)
The converter blowing method according to appendix 1, wherein a gradient obtained by dividing the amount of change in dust generation speed of the converter by the amount of change in lance gap is used to correct the deviation amount. Alchemy method.

In the converter blowing method, in the deviation amount calculation step, the dust generation speed calculated in the speed calculation step with respect to the relationship R1 between the number of times the upper blow lance is used and the dust generation speed when the lance gap is set to an optimum interval is obtained. Since the deviation amount is obtained and the lance gap is adjusted so that the deviation amount obtained in the deviation amount calculation step is corrected from the relationship R2 between the lance gap and each change amount of the dust generation speed in the position adjustment step, an appropriate lance gap is obtained. Can be blown.
As a result, excessively soft blow (larger lance gap) results in excessive dust, and excessive hard blow (smaller lance gap) significantly reduces the life of the top blow lance. Can be suppressed and further prevented.

All documents, patent applications, and technical standards mentioned in this specification are to the same extent as if each individual document, patent application, and technical standard were specifically and individually described to be incorporated by reference, Incorporated herein by reference.

DESCRIPTION OF SYMBOLS 10 Converter 11 Top blowing lance 11A Nozzle 16 Vibrating density meter (density meter)
G Lance gap GR Dust generation speed N Number of lance usage

Claims

A converter blowing method in which oxygen gas is blown from the nozzle of the top blowing lance to the hot metal surface in the converter,
A speed calculating step of calculating the dust generation speed in the converter by obtaining the amount of dust in the exhaust gas generated during blowing,
The speed with respect to the relationship R1 between the number of times the upper blowing lance is used and the dust generation speed when the lance gap, which is the distance between the hot metal surface and the tip of the upper blowing lance, is set to an optimum interval. A deviation amount calculating step for obtaining a deviation amount of the dust generation speed calculated in the calculating step;
In order to correct the deviation amount obtained in the deviation amount calculation step from the relationship R2 between the change amount of the lance gap and the change amount of the dust generation speed obtained in advance, the lance gap is changed during the blowing. A position adjustment process to be adjusted;
A converter blowing method.
The converter blowing method according to claim 1, wherein a gradient obtained by dividing the amount of change in the dust generation rate by the amount of change in the lance gap is used to correct the deviation amount.
In the speed calculation step, the collected dust obtained by wet collection of the exhaust gas is continuously collected, passed through a density meter and a thermometer, and measured by the density meter and the density of the collected dust. The converter blowing method according to claim 1 or 2, wherein the dust amount is obtained by calculating a dust concentration in the dust collection water from a difference from a density of pure water predicted from a temperature of the collected dust collection water. .