KR102283576B1 - Mechanical Agitated Desulfurization System - Google Patents

Abstract

Provided is a mechanically stirred desulfurization system capable of detecting the hot water level of molten iron in a simple way and automatically adjusting the lance to the optimal position according to the detected hot water level.
A control unit 14 for performing movement control so that the tip of the upper blowing lance 10 is at a position of a predetermined height from the hot water surface of the molten iron pot 2, the control unit 14 is a pre-treatment of the desulfurization treatment, slag removal treatment Calculate the freeboard (ΔH) of the molten iron pan 2 through the inclination angle of the molten iron pan 2 and the inner diameter (D) of the molten iron pan 2, and based on the calculated freeboard, the movement distance (L) of the upper blow lance ), and based on the calculated moving distance (L), the end of the upper blow lance is at a predetermined height from the hot water surface of the molten iron pot 2 to drive the upper blow lance 10 Lance driving means, characterized in that provided with.

Description

Mechanical Agitated Desulfurization System

The present invention relates to a mechanically stirred desulfurization system comprising a mechanically stirred desulfurization device and a lance for blowing a gas for blowing a desulfurizing agent into the mechanically stirred desulfurizing device.

As a representative equipment used to perform dephosphorization/desulfurization of molten iron, a dephosphorization/desulfurization agent is put into a refining vessel containing molten iron, and a machine for mechanically stirring the molten iron using a stirring impeller Stirred desulfurization devices are known.

In these facilities, a gravity drop method is conventionally employed as a method of adding a desulfurization agent. However, in this method, a part of the desulfurization agent scatters and is sucked into the dust collector during addition, or the desulfurization agent aggregates to reduce the desulfurization efficiency. There was a problem that the addition yield was low.

Accordingly, on the bath surface of the molten iron being stirred, a desulfurization agent is continuously blown from a cylinder called a top blowing lance at high speed using a transport gas such as argon gas or nitrogen gas, and the desulfurization agent is added into the molten iron ( For example, refer to patent document 1) was used.

Patent Document 1: Japanese Patent Application Laid-Open No. 2005-179690 Patent Document 2: Japanese Patent Application Laid-Open No. 2004-301362

In the method of spraying the desulfurization agent on the hot water surface of molten iron using such a top blowing lance, the height of the lance with respect to the hot water level contributes greatly to the desulfurization efficiency.

For example, if the distance between the lance and the hot water surface is long (800 mm or more) at the time of injection, the desulfurization efficiency is deteriorated because the amount of desulfurization agent input is reduced due to suction by the dust collector. Conversely, if the distance between the lance and the tang face is close (400mm or less), the lance end will be melted by the molten iron and the service life of the lance will be shortened.

Therefore, it is important to adjust the height of the lance to the level of the tangent (recommended height of the lance to the surface: 500 to 700 mm).

In addition, since the amount of molten iron differs for each treatment, and the shape of the treatment pan greatly fluctuates with each treatment due to the ingot attached to the inside of the pan, it is necessary to measure the level of the hot water level every time.

As a method of measuring the level of the molten iron conventionally, the following are known.

(1) A method to obtain the volume by dividing the weight of the molten iron by the specific gravity, and to obtain the height (the level of the hot water level) by dividing it by the floor area of the molten iron

However, this method has a problem in that precision is not very good because the bottom area becomes small when a metal is attached to the inside (refractory material) of the pot, or, conversely, when the inside of the pot is worn out, the bottom area becomes large.

(2) A method of measuring the level of the hot water surface using a sensor that transmits and receives microwaves through the opening direction of the top of the molten iron pot

However, during actual measurement, heat-resistant measures such as inserting a heat-resistant board to surround the sensor and suppressing the internal temperature rise are necessary to prevent failure due to radiant heat from molten iron. When it is attached and deposited on the heat-resistant board, there is a problem that the microwave is attenuated, making it impossible to measure the level of the hot water surface.

(3) Method of determining the change in luminance of the molten iron when the stirring impeller is immersed in the molten iron visually or by imaging it with a camera

However, in the case of visual confirmation, there is a problem in terms of workload and labor saving because the operator must always monitor the hot water surface. Moreover, in the determination by a camera, there exists a problem that a deviation generate|occur|produces in the detection precision by the property, the amount of generation, and the distribution state of the slag floating on the surface of molten iron|metal. Furthermore, the risk of camera failure due to the surrounding environment is also high.

In consideration of these conventional problems, a method of detecting the splash that occurs at the moment when the tip of the stirring impeller touches the hot water surface of the molten iron, and measuring the level of the molten iron through the value of the encoder installed on the motor shaft for lifting and lowering the stirring impeller at that time is proposed. There is (refer to Patent Document 2).

However, this method not only deteriorates the steelmaking yield by damaging the refractory material in the molten iron pot by the generated splash, but also avoids the problem that the monitoring camera that detects the splash easily breaks down at high temperature.

The present invention has been made in view of the above problems, and provides a mechanically stirred desulfurization system capable of detecting the hot water level of molten iron in a simple way and automatically adjusting the lance to the optimal position according to the detected hot water level. aim to do

The present invention is provided with a mechanically stirred desulfurization device (hereinafter referred to as "desulfurization device") having a stirring impeller and molten iron, and a top blowing lance for injecting a desulfurization agent into the molten iron pot of the desulfurization device, and the molten iron put into the molten iron pot It relates to a mechanically stirred desulfurization system for performing the desulfurization treatment of Further comprising a control unit, wherein the control unit is a freeboard of the molten iron pot through a tilting angle (θ) of the molten iron pot and the inner diameter (D) of the molten iron pot during the slag removal treatment, which is a pretreatment of the desulfurization treatment. (ΔH) and moving distance calculation means for calculating the moving distance (h) of the top blow lance based on the calculated freeboard, and based on the calculated moving distance, the tip of the top blow lance is the molten iron pot It is achieved by a mechanically stirred desulfurization system, characterized in that it is provided with a lance driving means for performing the driving of the upper blow lance so as to be at a position of a predetermined height (H) from the hot water surface of the.

According to the mechanically stirred desulfurization system according to the present invention, it is possible to detect the molten iron molten iron level in a simple manner and automatically adjust the lance to the optimal position according to the detected molten metal level.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the pre-processing state of desulfurization process.
2 is a view showing a driving method for inclining the molten iron pan.
3 is a view showing a general desulfurization treatment system.
4 is a view for explaining a method of obtaining the height (ΔH) of the freeboard portion of the molten iron pan through the tilt angle (θ) stored in the pre-processing.
Figure 5 is a view showing a case where the inner diameter (D) is narrowed (Fig. A) because the metal is attached to the refractory material inside the molten iron pan, and the inner diameter (D) is widened due to wear of the inner refractory material (Fig. B).
6 is a graph showing the relationship between the tilt angle θ and the height ΔH of the freeboard part.
7 is a schematic diagram showing the configuration of a mechanically stirred desulfurization system according to the present invention.
8 is a table of the relationship between the tilt angle θ and the height ΔH of the freeboard portion for each wear and tear condition of the pot.
9 shows an example of a flowchart showing the flow of control performed by the control unit.

Hereinafter, a mechanically stirred desulfurization system (hereinafter simply referred to as “desulfurization system”) according to the present invention will be described in detail with reference to the drawings. In general, the mechanical stirring desulfurization process (hereinafter simply referred to as “desulfurization process”) desulfurizes molten iron in the order of pre-treatment, desulfurization treatment, and post-treatment.

The pre-treatment is a process of removing the residue (slag) floating on the hot water surface with an extractor (slag skimmer) to increase the desulfurization efficiency before the desulfurization treatment.

1 is a view showing a pre-processing state.

(a) On the light copper bogie (1), tilt the molten iron pot (2) to the maximum angle at which the molten iron does not overflow. The tilt angle θ at this time is stored in a storage device (not shown).

(b) Scrape the residues floating on the hot water surface with the drainer (3) and transfer it to the slag pot (4). When the dregs are removed, the inclination of the molten iron pot is returned to its original position and moved to the next process.

2 : is a figure which shows the drive method for inclining the molten iron|metal pot 2. Fig. 2(A) shows a case where the actuator 5 for driving the tilt of the molten iron pan 2 is electric, and a rotating machine is provided on the shaft of the tilt gear. (B) is a view showing a case in which the actuator 5 is hydraulically driven, and the inclination angle changes as the hydraulic cylinder rod expands and contracts. Each of the encoders (not shown) is provided to convert a mechanical displacement amount (angle change or expansion/contraction amount) into an electrical signal. The output signal of the encoder is stored in a storage means (not shown), and the tilt angle can be known by reading the signal.

Next is the desulfurization process. 3 is a view showing a general desulfurization treatment system. The desulfurization treatment system includes an impeller 6 for stirring, a motor 7 for driving rotation of the impeller 6 for stirring, and a motor 7 for rotation driving, and raising and lowering the impeller 6 for stirring up and down A carriage provided with a lifting frame 8, a molten iron stirring unit having a lifting motor 9 for pulling the lifting frame with a rope, and a transport gas such as argon gas or nitrogen gas on the bath surface of the molten iron being stirred A top blowing lance 10 (hereinafter referred to as "lance") that continuously injects and adds a desulfurization agent at high speed using It is provided with the lance injection|throwing-in part provided with the lance drive means which has a motor 11, and the molten iron|metal pot 2 which is put on the tilting bogie 1, and into which molten iron|metal is injected|thrown-in.

In addition, the dust collector 12 is a device for collecting by sucking the desulfurization agent sprayed from the lance 10 without reaching the molten iron pot 2 and scattered in the air.

Desulfurization treatment is a treatment in which the sulfur in the molten iron reacts with the desulfurization agent by injecting and stirring the desulfurization agent into the molten iron.

The process is as follows.

(a) Drive the elevating motor 9 to lower the stirring impeller 6 together with the elevating frame 8 to a predetermined height, immerse it in the molten iron, and stir the molten iron with the rotating drive motor 7 .

(b) After the lance 10 is lowered according to the level of the hot water surface, a desulfurization agent is sprayed from the tip of the lance, and the desulfurization agent is stirred and mixed with molten iron to initiate a desulfurization reaction.

(c) When stirring is stopped, the desulfurization agent combined with the sulfur component in the molten iron floats on the surface of the molten iron as a residue. At this time, the motor 9 for raising/lowering is driven, the impeller 6 is lifted from the molten iron|metal pot 2, and it transfers to the next post-processing.

The post-treatment is a process of removing the residues floating on the surface of the hot water after the desulfurization treatment, and the operation is a process of inclining the molten iron pot (2) and removing the residues with the drainer (3), similarly to the pre-treatment. Since the operation is basically the same as the preprocessing, a detailed description is omitted.

In FIG. 3, the distance (H) between the lance and the tang surface is a problem, but in general, when H is about 400 mm or less, the end of the lance may be damaged by molten iron heat or splash of molten iron. When the desulfurization agent scatters and is sucked into the dust collector 12, there is a fear that the input amount of the desulfurization agent is reduced.

Therefore, it is usually performed by adjusting the position of the tip of the lance so that about 500mm ≤ H ≤ about 700mm. .

Therefore, if this ΔH is known in advance, it can be adjusted to an appropriate H.

4 is a view for explaining a method of obtaining the height (ΔH) of the freeboard portion of the molten iron pot through the tilt angle (θ) memorized in the preprocessing.

Fig. 4(A) is a view in the case of a cylindrical container. If the inclination angle in the case of inclination to the maximum angle at which the molten iron does not overflow is θ and the diameter of the container is D, the volume V of the space in the container can be expressed by the following equation.

V = (D/2) ² × π × ΔH ₀ × (1/2)

The amount of molten iron in the pot does not change even if the tilt is returned to its original state, so the volume of the freeboard space does not change. therefore,

V = (D/2) ² × π × ΔH

∴ (D/2) ² × π × ΔH ₀ × (1/2) = (D/2) ² π × ΔH

∴ ΔH = ΔH ₀ /2

But obviously

ΔH ₀ =D × tanθ

Because of,

∴ ΔH = (D × tanθ)/2 (Equation 1)

becomes

Therefore, ΔH is uniquely determined by the diameter (D) of the pot and the angle of inclination (θ) and does not depend on the amount of molten iron.

Next, Figure 4 (B) is a view showing the case of an actual molten iron pot, but it can be considered as the same as providing a notch in the portion indicated by a dotted line in the cylindrical container of (A), so it can be considered the same as the case of (A).

Through the tilt angle (θ) memorized in the preprocessing, the height (ΔH) of the freeboard part of the molten iron pan can be obtained using Equation 1 above.

What affects the change in the inner diameter (D) of the molten iron pan is the wear and tear of the refractory material due to the frequency of use of the molten iron pan or the narrowing of the inner diameter (D) due to the current attachment. Usually, both are combined to change D. Figure 5 is a view showing a case where the inner diameter (D) is narrowed (Figure A) due to metal attachments attached to the refractory material inside the molten iron pot, and the inner diameter (D) is widened due to wear of the inner refractory material (Figure B).

Accordingly, it is examined to what extent the height (ΔH) of the freeboard part is affected by the change in the inner diameter (D). Hereinafter, the “height of the free board portion” is simply referred to as a “free board”. If the freeboard ΔH' in the case where the current D changes by ΔD is calculated using Equation 1 above,

ΔH' = (D + ΔD) × tanθ/2 = Dtanθ/2 + ΔDtanθ/2

∴ ΔH' = ΔH + ΔDtanθ/2 (Equation 2)

At present, if ΔD is at most 200mm (100mm wear and tear as the thickness of the refractory material, 200mm wear and tear on the basis of the diameter), the increment (δ) of ΔH is

δ = 100tanθ(mm)

becomes When θ is 30°, 40°, and 45° (normally, the tilt angle is about 30° and the maximum is about 45°), δ is calculated as follows.

tan30° = 0.58 δ = 58mm

tan40° = 0.84 δ = 84mm

tan45° = 1 δ = 100mm

In other words, even if the inner diameter of the molten iron pot changes by 200mm, the base of the freeboard has only an error of 100mm even when the tilt angle is up to 45°, and the effect is small compared to the width of the preferred freeboard range (500mm to 700mm). see.

6 is a graph showing the relationship between the tilt angle θ and the freeboard. If the tilt angle is the same, it is visually shown that the influence of the wear and tear of the molten iron pot is small.

For example, in the area indicated by the arrow in the drawing (θ = around 36°), 6 types of wear and tear of the molten iron pot are indicated, but it can be seen that the range of the difference between the freeboards is converged within 100mm. . Therefore, even if the freeboard calculated using the inner diameter (D) of the standard molten iron pot (for example, a new pot) is applied to all cases, the effect is likely to be small.

Next, the configuration and operation of the desulfurization system according to the present invention will be described. 7 is a schematic diagram showing the configuration of a desulfurization system according to the present invention. Since the basic configuration is the same as that shown in FIG. 3, only other parts will be described.

The desulfurization system according to the present invention adds a control unit 14 for controlling the movement distance of the lance by a lance passing detection sensor 13 (photoelectric sensor) and a lance drive motor 11 to the conventional desulfurization system shown in FIG. 2 . did it

The tilt angle θ is measured at the stage of preprocessing, inputted to the control unit 14, and stored. In addition, the wear condition of the pot can be measured by actually measuring the inner diameter (D) before the start of the pretreatment and inputting the value, or if the degree of wear and tear is known in advance by the number of uses of the pot, input the number of uses It can also be converted to wear and tear (mm).

What the control part 14 automatically controls is moving the position of the tip of a lance from the tang surface to a predetermined height H, and stopping it there. For this purpose, the lance must be moved to the position, but the descent distance L (indicates the vertical distance after passing the lance passing detection sensor 13) is obtained by the following equation. That is, if the height from the upper end of the pot to the lance passing detection sensor 13 is L ₀ , and the freeboard of the pot is ΔH,

L + H = L ₀ + ΔH

becomes,

∴ L = L ₀ + ΔH - H (Equation 3)

The value of L ₀ is known in advance, and since about 500 mm ≤ H ≤ about 700 mm, for example, by setting H = 600 mm, L becomes a linear function of ΔH.

Accordingly, the lance can be automatically moved to an optimal position by calculating the freeboard ΔH by the above equation 1 based on the tilt angle θ.

In addition, when the slope of the lance in the vertical direction is α, the relationship between the descending distance L of the tip of the lance and the actual moving distance h in the traveling direction of the lance is

L = hcosα

appears as in other words,

H = Lsecα (Equation 4)

becomes By moving the lance in the traveling direction by the distance equal to this h, it is possible to move the lance by the desired descent distance L as a result.

The detection of the moving distance h in the traveling direction of the lance is possible by combining a photoelectric sensor and a lance lifting/lowering rotator (encoder) not shown.

With a lifting rotator (encoder), the position where the lance blocks the photoelectric sensor 13 is measured, and the moving distance from there is measured with the encoder.

Also, instead of using an encoder, it is possible to measure the length by setting a scale standard next to the lance and reading the scale with a camera.

In order to reduce the influence of the wear condition of the pot on the free board (ΔH), it is one way to table the relationship between the free board value calculated for each wear condition and the tilt angle in advance and change the table as needed. .

8 is a table of the relationship between the tilt angle θ and the free board for each wear and tear state of the pot. This is an example. It is more accurate to set the angle at intervals of 1°, but for the convenience of the ground, it is displayed at intervals of 5°. If the angle is the same, it can be seen that the change in the freeboard ΔH due to the wear and tear is small. For example, when the tilt angle was 30°, the freeboard only changed by 58mm even if 100mm was worn. In addition, even in the case of 45°, even if 100 mm is worn, the free board only changes by 100 mm, and it can be seen that the influence is small compared to the width of the preferred free board range (500 mm to 700 mm).

9 shows an example of a flowchart showing the flow of control performed by the control unit 14. As shown in FIG.

As a premise, the wear state (wear wear degree) of the molten iron pot used on the day and the tilt angle (θ) measured in the pre-processing are input in advance and stored.

When the program of the control unit 14 is started, first, the CPU (not shown) of the control unit 14 reads the wear and tear (or the number of times of use) of the molten iron pan based on a predetermined program (S1). Next, the tilt angle θ is read (S2). The freeboard ΔH corresponding to the inclination angle θ is read with reference to the freeboard table corresponding to the wear and tear of the molten iron pan (for example, the table shown in FIG. 8) (S3).

A descent distance L of the lance is calculated based on the read freeboard ΔH (S4). The above formula 3 is used for calculation of the descent distance L of the lance. Then, the movement distance (h) of the lance is calculated using Equation 4 above.

The lance driving motor 11 is driven to start driving the lance (S5). When the lance passes the lance detection sensor 13 (YES in step S6), measurement of the movement distance of the lance is started (S7). With a lifting and lowering rotary machine (encoder), the movement distance from the point at which the lance blocks the photoelectric sensor 13 is measured.

When the moving distance of the lance reaches the moving distance h obtained in the above formula (4) (YES in step S8), the driving (moving) of the lance is stopped (S9).

The injection of the desulfurization agent through the lance is started at the position where the lance is stopped (S10).

ADVANTAGE OF THE INVENTION According to this invention, in all the processes, the distance to a desulfurization agent injection|throwing-in lance and a hot water surface can be made constant, and it is possible to ensure the distance considered optimal uniformly also about any condition. Through this, the desulfurization agent is not sucked into the dust collector and the desulfurization agent enters the inside of the stirred molten iron efficiently, enabling stable desulfurization treatment. This effect makes it possible to greatly increase the success rate of the desulfurization treatment. Furthermore, the amount of dissolution loss at the end of the lance due to the approach to the molten iron surface becomes small, and it becomes possible to significantly increase the service life of the lance tube.

1: Hard copper bogie, 2: Molten iron pot, 3: Exhaust machine, 4: Slag pot, 5: Actuator, 6: Stirring impeller, 7: Rotating drive motor, 8: Elevating frame, 9: Elevating motor, 10: Upper blow lance , 11: lance drive motor, 12: dust collector, 13: lance passing detection sensor, 14: control unit

Claims (2)

A mechanical stirring desulfurization device (hereinafter referred to as “desulfurization device”) having a stirring impeller and a molten iron pot, and a top blow lance for injecting a desulfurization agent into the molten iron pot of the desulfurization device, the molten iron put into the molten iron pot A mechanically stirred desulfurization system for performing desulfurization treatment, comprising:
The system is
Further comprising a control unit for performing movement control so that the end of the upper blow lance is positioned at a predetermined height from the hot water surface of the molten iron pot,
The control unit is
Calculating the freeboard of the molten iron pot through the inclination angle of the molten iron pot and the inner diameter of the molten iron pot when the molten iron pot is tilted to the maximum angle at which the molten iron does not overflow during the slag removal treatment, which is a pretreatment of the desulfurization treatment, and the calculation A moving distance calculating means for calculating the moving distance of the upper lance based on one free board;
Based on the calculated moving distance, mechanical stirring desulfurization system, characterized in that provided with a lance driving means for driving the top blowing lance so that the tip of the top blowing lance is at a predetermined height from the hot water surface of the molten iron pot. According to claim 1,
The movement distance calculation means of the control unit includes a table in which the tilt angle and the free board are related for each wear degree of the molten iron pot, and based on the free board obtained using the table corresponding to the input wear degree Mechanical stirring desulfurization system, characterized in that for calculating the moving distance of the upper blow lance.

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